Add performance rubocop and fixes

Reduce allocations while registering Liquid tags

.github/probots.yml

@@ -0,0 +1,2 @@
+enabled:
+  - cla

.gitignore

@@ -4,5 +4,8 @@
 pkg
 *.rbc
 .rvmrc
+.idea
 .ruby-version
 Gemfile.lock
+.bundle
+.byebug_history

.rubocop.yml

@@ -0,0 +1,10 @@
+inherit_from:
+  - .rubocop.shopify.yml
+
+require: rubocop-performance
+
+Performance:
+  Enabled: true
+
+Metrics/LineLength:
+  Enabled: false

.travis.yml

@@ -1,16 +1,30 @@
+language: ruby
+
 rvm:
-  - 1.9
-  - 2.0
-  - 2.1
-  - jruby-19mode
+  - 2.4
+  - 2.5
+  - 2.6
+  - 2.7
+  - ruby-head
   - jruby-head
-  - rbx-2
+  - truffleruby
+
+sudo: false
+
+addons:
+  apt:
+    packages:
+    - libgmp3-dev
+
 matrix:
   allow_failures:
-    - rvm: rbx-2
+    - rvm: ruby-head
     - rvm: jruby-head
 
-script: "rake test"
+install:
+  - bundle install
+
+script: bundle exec rake
 
 notifications:
   disable: true

CONTRIBUTING.md

@@ -4,23 +4,22 @@
 
 * Bugfixes
 * Performance improvements
-* Features which are likely to be useful to the majority of Liquid users
+* Features that are likely to be useful to the majority of Liquid users
 
 ## Things we won't merge
 
-* Code which introduces considerable performance degrations
-* Code which touches performance critical parts of Liquid and comes without benchmarks
-* Features which are not important for most people (we want to keep the core Liquid code small and tidy)
-* Features which can easily be implemented on top of Liquid (for example as a custom filter or custom filesystem)
-* Code which comes without tests
-* Code which breaks existing tests
+* Code that introduces considerable performance degrations
+* Code that touches performance-critical parts of Liquid and comes without benchmarks
+* Features that are not important for most people (we want to keep the core Liquid code small and tidy)
+* Features that can easily be implemented on top of Liquid (for example as a custom filter or custom filesystem)
+* Code that does not include tests
+* Code that breaks existing tests
 
 ## Workflow
 
 * Fork the Liquid repository
 * Create a new branch in your fork
-* If it makes sense, add tests for your code and run a performance benchmark
-* Make sure all tests pass
+* If it makes sense, add tests for your code and/or run a performance benchmark
+* Make sure all tests pass (`bundle exec rake`)
 * Create a pull request
-* In the description, ping one of [@boourns](https://github.com/boourns), [@fw42](https://github.com/fw42), [@camilo](https://github.com/camilo), [@dylanahsmith](https://github.com/dylanahsmith), or [@arthurnn](https://github.com/arthurnn) and ask for a code review.
 

Gemfile

@@ -1,8 +1,26 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
+git_source(:github) do |repo_name|
+  "https://github.com/#{repo_name}.git"
+end
 
 gemspec
-gem 'stackprof', platforms: :mri_21
+
+group :benchmark, :test do
+  gem 'benchmark-ips'
+  gem 'memory_profiler'
+
+  install_if -> { RUBY_PLATFORM !~ /mingw|mswin|java/ && RUBY_ENGINE != 'truffleruby' } do
+    gem 'stackprof'
+  end
+end
 
 group :test do
-  gem 'spy', '0.4.1'
+  gem 'rubocop', '~> 0.74.0', require: false
+  gem 'rubocop-performance', require: false
+
+  platform :mri, :truffleruby do
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: '7ba926791ef8411984d0f3e41c6353fd716041c6'
+  end
 end

History.md

@@ -1,42 +1,170 @@
-# Liquid Version History
+# Liquid Change Log
 
-## 3.0.0 / not yet released / branch "master"
+## 4.0.3 / 2019-03-12
 
-* ...
-* Add exception_handler feature, see #397 and #254 [Bogdan Gusiev, bogdan and Florian Weingarten, fw42]
-* Optimize variable parsing to avoid repeated regex evaluation during template rendering #383 [Jason Hiltz-Laforge, jasonhl]
-* Optimize checking for block interrupts to reduce object allocation #380 [Jason Hiltz-Laforge, jasonhl] 
-* Properly set context rethrow_errors on render! #349 [Thierry Joyal, tjoyal]
-* Fix broken rendering of variables which are equal to false, see #345 [Florian Weingarten, fw42]
-* Remove ActionView template handler [Dylan Thacker-Smith, dylanahsmith]
-* Freeze lots of string literals for new Ruby 2.1 optimization, see #297 [Florian Weingarten, fw42]
-* Allow newlines in tags and variables, see #324 [Dylan Thacker-Smith, dylanahsmith]
-* Tag#parse is called after initialize, which now takes options instead of tokens as the 3rd argument. See #321 [Dylan Thacker-Smith, dylanahsmith]
-* Raise `Liquid::ArgumentError` instead of `::ArgumentError` when filter has wrong number of arguments #309 [Bogdan Gusiev, bogdan]
-* Add a to_s default for liquid drops, see #306 [Adam Doeler, releod]
-* Add strip, lstrip, and rstrip to standard filters [Florian Weingarten, fw42]
-* Make if, for & case tags return complete and consistent nodelists, see #250 [Nick Jones, dntj]
-* Prevent arbitrary method invocation on condition objects, see #274 [Dylan Thacker-Smith, dylanahsmith]
-* Don't call to_sym when creating conditions for security reasons, see #273 [Bouke van der Bijl, bouk]
-* Fix resource counting bug with respond_to?(:length), see #263 [Florian Weingarten, fw42]
-* Allow specifying custom patterns for template filenames, see #284 [Andrei Gladkyi, agladkyi]
-* Allow drops to optimize loading a slice of elements, see #282 [Tom Burns, boourns]
-* Support for passing variables to snippets in subdirs, see #271 [Joost Hietbrink, joost]
-* Add a class cache to avoid runtime extend calls, see #249 [James Tucker, raggi]
-* Remove some legacy Ruby 1.8 compatibility code, see #276 [Florian Weingarten, fw42]
-* Add default filter to standard filters, see #267 [Derrick Reimer, djreimer]
-* Add optional strict parsing and warn parsing, see #235 [Tristan Hume, trishume]
-* Add I18n syntax error translation, see #241 [Simon Hørup Eskildsen, Sirupsen]
-* Make sort filter work on enumerable drops, see #239 [Florian Weingarten, fw42]
-* Fix clashing method names in enumerable drops, see #238 [Florian Weingarten, fw42]
-* Make map filter work on enumerable drops, see #233 [Florian Weingarten, fw42]
-* Improved whitespace stripping for blank blocks, related to #216 [Florian Weingarten, fw42]
+### Fixed
+* Fix break and continue tags inside included templates in loops (#1072) [Justin Li]
 
-## 2.6.1 / 2014-01-10 / branch "2-6-stable"
+## 4.0.2 / 2019-03-08
+
+### Changed
+* Add `where` filter (#1026) [Samuel Doiron]
+* Add `ParseTreeVisitor` to iterate the Liquid AST (#1025) [Stephen Paul Weber]
+* Improve `strip_html` performance (#1032) [printercu]
+
+### Fixed
+* Add error checking for invalid combinations of inputs to sort, sort_natural, where, uniq, map, compact filters (#1059) [Garland Zhang]
+* Validate the character encoding in url_decode (#1070) [Clayton Smith]
+
+## 4.0.1 / 2018-10-09
+
+### Changed
+* Add benchmark group in Gemfile (#855) [Jerry Liu]
+* Allow benchmarks to benchmark render by itself (#851) [Jerry Liu]
+* Avoid calling `line_number` on String node when rescuing a render error. (#860) [Dylan Thacker-Smith]
+* Avoid duck typing to detect whether to call render on a node. [Dylan Thacker-Smith]
+* Clarify spelling of `reversed` on `for` block tag (#843) [Mark Crossfield]
+* Replace recursion with loop to avoid potential stack overflow from malicious input (#891, #892) [Dylan Thacker-Smith]
+* Limit block tag nesting to 100 (#894) [Dylan Thacker-Smith]
+* Replace `assert_equal nil` with `assert_nil` (#895) [Dylan Thacker-Smith]
+* Remove Spy Gem (#896) [Dylan Thacker-Smith]
+* Add `collection_name` and `variable_name` reader to `For` block (#909)
+* Symbols render as strings (#920) [Justin Li]
+* Remove default value from Hash objects (#932) [Maxime Bedard]
+* Remove one level of nesting (#944) [Dylan Thacker-Smith]
+* Update Rubocop version (#952) [Justin Li]
+* Add `at_least` and `at_most` filters (#954, #958) [Nithin Bekal]
+* Add a regression test for a liquid-c trim mode bug (#972) [Dylan Thacker-Smith]
+* Use https rather than git protocol to fetch liquid-c [Dylan Thacker-Smith]
+* Add tests against Ruby 2.4 (#963) and 2.5 (#981)
+* Replace RegExp literals with constants (#988) [Ashwin Maroli]
+* Replace unnecessary `#each_with_index` with `#each` (#992) [Ashwin Maroli]
+* Improve the unexpected end delimiter message for block tags. (#1003) [Dylan Thacker-Smith]
+* Refactor and optimize rendering (#1005) [Christopher Aue]
+* Add installation instruction (#1006) [Ben Gift]
+* Remove Circle CI (#1010)
+* Rename deprecated `BigDecimal.new` to `BigDecimal` (#1024) [Koichi ITO]
+* Rename deprecated Rubocop name (#1027) [Justin Li]
+
+### Fixed
+* Handle `join` filter on non String joiners (#857) [Richard Monette]
+* Fix duplicate inclusion condition logic error of `Liquid::Strainer.add_filter` method (#861)
+* Fix `escape`, `url_encode`, `url_decode` not handling non-string values (#898) [Thierry Joyal]
+* Fix raise when variable is defined but nil when using `strict_variables` [Pascal Betz]
+* Fix `sort` and `sort_natural` to handle arrays with nils (#930) [Eric Chan]
+
+## 4.0.0 / 2016-12-14 / branch "4-0-stable"
+
+### Changed
+* Render an opaque internal error by default for non-Liquid::Error (#835) [Dylan Thacker-Smith]
+* Ruby 2.0 support dropped (#832) [Dylan Thacker-Smith]
+* Add to_number Drop method to allow custom drops to work with number filters (#731)
+* Add strict_variables and strict_filters options to detect undefined references (#691)
+* Improve loop performance (#681) [Florian Weingarten]
+* Rename Drop method `before_method` to `liquid_method_missing` (#661) [Thierry Joyal]
+* Add url_decode filter to invert url_encode (#645) [Larry Archer]
+* Add global_filter to apply a filter to all output (#610) [Loren Hale]
+* Add compact filter (#600) [Carson Reinke]
+* Rename deprecated "has_key?" and "has_interrupt?" methods (#593) [Florian Weingarten]
+* Include template name with line numbers in render errors (574) [Dylan Thacker-Smith]
+* Add sort_natural filter (#554) [Martin Hanzel]
+* Add forloop.parentloop as a reference to the parent loop (#520) [Justin Li]
+* Block parsing moved to BlockBody class (#458) [Dylan Thacker-Smith]
+* Add concat filter to concatenate arrays (#429) [Diogo Beato]
+* Ruby 1.9 support dropped (#491) [Justin Li]
+* Liquid::Template.file_system's read_template_file method is no longer passed the context. (#441) [James Reid-Smith]
+* Remove `liquid_methods` (See https://github.com/Shopify/liquid/pull/568 for replacement)
+* Liquid::Template.register_filter raises when the module overrides registered public methods as private or protected (#705) [Gaurav Chande]
+
+### Fixed
+
+* Fix variable names being detected as an operator when starting with contains (#788) [Michael Angell]
+* Fix include tag used with strict_variables (#828) [QuickPay]
+* Fix map filter when value is a Proc (#672) [Guillaume Malette]
+* Fix truncate filter when value is not a string (#672) [Guillaume Malette]
+* Fix behaviour of escape filter when input is nil (#665) [Tanel Jakobsoo]
+* Fix sort filter behaviour with empty array input (#652) [Marcel Cary]
+* Fix test failure under certain timezones (#631) [Dylan Thacker-Smith]
+* Fix bug in uniq filter (#595) [Florian Weingarten]
+* Fix bug when "blank" and "empty" are used as variable names (#592) [Florian Weingarten]
+* Fix condition parse order in strict mode (#569) [Justin Li]
+* Fix naming of the "context variable" when dynamically including a template (#559) [Justin Li]
+* Gracefully accept empty strings in the date filter (#555) [Loren Hale]
+* Fix capturing into variables with a hyphen in the name (#505) [Florian Weingarten]
+* Fix case sensitivity regression in date standard filter (#499) [Kelley Reynolds]
+* Disallow filters with no variable in strict mode (#475) [Justin Li]
+* Disallow variable names in the strict parser that are not valid in the lax parser (#463) [Justin Li]
+* Fix BlockBody#warnings taking exponential time to compute (#486) [Justin Li]
+
+## 3.0.5 / 2015-07-23 / branch "3-0-stable"
+
+* Fix test failure under certain timezones [Dylan Thacker-Smith]
+
+## 3.0.4 / 2015-07-17
+
+* Fix chained access to multi-dimensional hashes [Florian Weingarten]
+
+## 3.0.3 / 2015-05-28
+
+* Fix condition parse order in strict mode (#569) [Justin Li]
+
+## 3.0.2 / 2015-04-24
+
+* Expose VariableLookup private members (#551) [Justin Li]
+* Documentation fixes
+
+## 3.0.1 / 2015-01-23
+
+* Remove duplicate `index0` key in TableRow tag (#502) [Alfred Xing]
+
+## 3.0.0 / 2014-11-12
+
+* Removed Block#end_tag. Instead, override parse with `super` followed by your code. See #446 [Dylan Thacker-Smith]
+* Fixed condition with wrong data types (#423) [Bogdan Gusiev]
+* Add url_encode to standard filters (#421) [Derrick Reimer]
+* Add uniq to standard filters [Florian Weingarten]
+* Add exception_handler feature (#397) and #254 [Bogdan Gusiev, Florian Weingarten]
+* Optimize variable parsing to avoid repeated regex evaluation during template rendering #383 [Jason Hiltz-Laforge]
+* Optimize checking for block interrupts to reduce object allocation #380 [Jason Hiltz-Laforge]
+* Properly set context rethrow_errors on render! #349 [Thierry Joyal]
+* Fix broken rendering of variables which are equal to false (#345) [Florian Weingarten]
+* Remove ActionView template handler [Dylan Thacker-Smith]
+* Freeze lots of string literals for new Ruby 2.1 optimization (#297) [Florian Weingarten]
+* Allow newlines in tags and variables (#324) [Dylan Thacker-Smith]
+* Tag#parse is called after initialize, which now takes options instead of tokens as the 3rd argument. See #321 [Dylan Thacker-Smith]
+* Raise `Liquid::ArgumentError` instead of `::ArgumentError` when filter has wrong number of arguments #309 [Bogdan Gusiev]
+* Add a to_s default for liquid drops (#306) [Adam Doeler]
+* Add strip, lstrip, and rstrip to standard filters [Florian Weingarten]
+* Make if, for & case tags return complete and consistent nodelists (#250) [Nick Jones]
+* Prevent arbitrary method invocation on condition objects (#274) [Dylan Thacker-Smith]
+* Don't call to_sym when creating conditions for security reasons (#273) [Bouke van der Bijl]
+* Fix resource counting bug with respond_to?(:length) (#263) [Florian Weingarten]
+* Allow specifying custom patterns for template filenames (#284) [Andrei Gladkyi]
+* Allow drops to optimize loading a slice of elements (#282) [Tom Burns]
+* Support for passing variables to snippets in subdirs (#271) [Joost Hietbrink]
+* Add a class cache to avoid runtime extend calls (#249) [James Tucker]
+* Remove some legacy Ruby 1.8 compatibility code (#276) [Florian Weingarten]
+* Add default filter to standard filters (#267) [Derrick Reimer]
+* Add optional strict parsing and warn parsing (#235) [Tristan Hume]
+* Add I18n syntax error translation (#241) [Simon Hørup Eskildsen, Sirupsen]
+* Make sort filter work on enumerable drops (#239) [Florian Weingarten]
+* Fix clashing method names in enumerable drops (#238) [Florian Weingarten]
+* Make map filter work on enumerable drops (#233) [Florian Weingarten]
+* Improved whitespace stripping for blank blocks, related to #216 [Florian Weingarten]
+
+## 2.6.3 / 2015-07-23 / branch "2-6-stable"
+
+* Fix test failure under certain timezones [Dylan Thacker-Smith]
+
+## 2.6.2 / 2015-01-23
+
+* Remove duplicate hash key [Parker Moore]
+
+## 2.6.1 / 2014-01-10
 
 Security fix, cherry-picked from master (4e14a65):
-* Don't call to_sym when creating conditions for security reasons, see #273 [Bouke van der Bijl, bouk]
-* Prevent arbitrary method invocation on condition objects, see #274 [Dylan Thacker-Smith, dylanahsmith]
+* Don't call to_sym when creating conditions for security reasons (#273) [Bouke van der Bijl]
+* Prevent arbitrary method invocation on condition objects (#274) [Dylan Thacker-Smith]
 
 ## 2.6.0 / 2013-11-25
 
@@ -44,37 +172,37 @@ IMPORTANT: Liquid 2.6 is going to be the last version of Liquid which maintains
 The following releases will only be tested against Ruby 1.9 and Ruby 2.0 and are likely to break on Ruby 1.8.
 
 * Bugfix for #106: fix example servlet [gnowoel]
-* Bugfix for #97: strip_html filter supports multi-line tags [Jo Liss, joliss]
-* Bugfix for #114: strip_html filter supports style tags [James Allardice, jamesallardice]
-* Bugfix for #117: 'now' support for date filter in Ruby 1.9 [Notre Dame Webgroup, ndwebgroup]
-* Bugfix for #166: truncate filter on UTF-8 strings with Ruby 1.8 [Florian Weingarten, fw42]
-* Bugfix for #204: 'raw' parsing bug [Florian Weingarten, fw42]
-* Bugfix for #150: 'for' parsing bug [Peter Schröder, phoet]
-* Bugfix for #126: Strip CRLF in strip_newline [Peter Schröder, phoet]
-* Bugfix for #174, "can't convert Fixnum into String" for "replace" [wǒ_is神仙, jsw0528]
-* Allow a Liquid::Drop to be passed into Template#render [Daniel Huckstep, darkhelmet]
-* Resource limits [Florian Weingarten, fw42]
-* Add reverse filter [Jay Strybis, unreal]
+* Bugfix for #97: strip_html filter supports multi-line tags [Jo Liss]
+* Bugfix for #114: strip_html filter supports style tags [James Allardice]
+* Bugfix for #117: 'now' support for date filter in Ruby 1.9 [Notre Dame Webgroup]
+* Bugfix for #166: truncate filter on UTF-8 strings with Ruby 1.8 [Florian Weingarten]
+* Bugfix for #204: 'raw' parsing bug [Florian Weingarten]
+* Bugfix for #150: 'for' parsing bug [Peter Schröder]
+* Bugfix for #126: Strip CRLF in strip_newline [Peter Schröder]
+* Bugfix for #174, "can't convert Fixnum into String" for "replace" [jsw0528]
+* Allow a Liquid::Drop to be passed into Template#render [Daniel Huckstep]
+* Resource limits [Florian Weingarten]
+* Add reverse filter [Jay Strybis]
 * Add utf-8 support
-* Use array instead of Hash to keep the registered filters [Tasos Stathopoulos, astathopoulos]
-* Cache tokenized partial templates [Tom Burns, boourns]
-* Avoid warnings in Ruby 1.9.3 [Marcus Stollsteimer, stomar]
-* Better documentation for 'include' tag (closes #163) [Peter Schröder, phoet]
-* Use of BigDecimal on filters to have better precision (closes #155) [Arthur Nogueira Neves, arthurnn]
+* Use array instead of Hash to keep the registered filters [Tasos Stathopoulos]
+* Cache tokenized partial templates [Tom Burns]
+* Avoid warnings in Ruby 1.9.3 [Marcus Stollsteimer]
+* Better documentation for 'include' tag (closes #163) [Peter Schröder]
+* Use of BigDecimal on filters to have better precision (closes #155) [Arthur Nogueira Neves]
 
 ## 2.5.5 / 2014-01-10 / branch "2-5-stable"
 
 Security fix, cherry-picked from master (4e14a65):
-* Don't call to_sym when creating conditions for security reasons, see #273 [Bouke van der Bijl, bouk]
-* Prevent arbitrary method invocation on condition objects, see #274 [Dylan Thacker-Smith, dylanahsmith]
+* Don't call to_sym when creating conditions for security reasons (#273) [Bouke van der Bijl]
+* Prevent arbitrary method invocation on condition objects (#274) [Dylan Thacker-Smith]
 
 ## 2.5.4 / 2013-11-11
 
-* Fix "can't convert Fixnum into String" for "replace", see #173, [wǒ_is神仙, jsw0528]
+* Fix "can't convert Fixnum into String" for "replace" (#173), [jsw0528]
 
 ## 2.5.3 / 2013-10-09
 
-* #232, #234, #237: Fix map filter bugs [Florian Weingarten, fw42]
+* #232, #234, #237: Fix map filter bugs [Florian Weingarten]
 
 ## 2.5.2 / 2013-09-03 / deleted
 
@@ -82,7 +210,7 @@ Yanked from rubygems, as it contained too many changes that broke compatibility.
 
 ## 2.5.1 / 2013-07-24
 
-* #230: Fix security issue with map filter, Use invoke_drop in map filter [Florian Weingarten, fw42]
+* #230: Fix security issue with map filter, Use invoke_drop in map filter [Florian Weingarten]
 
 ## 2.5.0 / 2013-03-06
 
@@ -146,7 +274,7 @@ Yanked from rubygems, as it contained too many changes that broke compatibility.
 * Fixed bad error reporting when a filter called a method which doesn't exist. Liquid told you that it couldn't find the filter which was obviously misleading [Tobias Luetke]
 * Removed count helper from standard lib. use size [Tobias Luetke]
 * Fixed bug with string filter parameters failing to tolerate commas in strings. [Paul Hammond]
-* Improved filter parameters. Filter parameters are now context sensitive; Types are resolved according to the rules of the context. Multiple parameters are now separated by the Liquid::ArgumentSeparator: , by default [Paul Hammond]
+* Improved filter parameters. Filter parameters are now context sensitive; Types are resolved according to the rules of the context. Multiple parameters are now separated by the Liquid::ARGUMENT_SEPARATOR: , by default [Paul Hammond]
     {{ 'Typo' | link_to: 'http://typo.leetsoft.com', 'Typo - a modern weblog engine' }}
 * Added Liquid::Drop. A base class which you can use for exporting proxy objects to liquid which can acquire more data when used in liquid. [Tobias Luetke]
 

README.md

@@ -1,5 +1,5 @@
-[![Build Status](https://secure.travis-ci.org/Shopify/liquid.png?branch=master)](http://travis-ci.org/Shopify/liquid)
-[![Inline docs](http://inch-ci.org/github/Shopify/liquid.png)](http://inch-ci.org/github/Shopify/liquid)
+[![Build Status](https://api.travis-ci.org/Shopify/liquid.svg?branch=master)](http://travis-ci.org/Shopify/liquid)
+[![Inline docs](http://inch-ci.org/github/Shopify/liquid.svg?branch=master)](http://inch-ci.org/github/Shopify/liquid)
 
 # Liquid template engine
 
@@ -42,6 +42,8 @@ Liquid is a template engine which was written with very specific requirements:
 
 ## How to use Liquid
 
+Install Liquid by adding `gem 'liquid'` to your gemfile.
+
 Liquid supports a very simple API based around the Liquid::Template class.
 For standard use you can just pass it the content of a file and call render with a parameters hash.
 
@@ -73,3 +75,34 @@ This is useful for doing things like enabling strict mode only in the theme edit
 
 It is recommended that you enable `:strict` or `:warn` mode on new apps to stop invalid templates from being created.
 It is also recommended that you use it in the template editors of existing apps to give editors better error messages.
+
+### Undefined variables and filters
+
+By default, the renderer doesn't raise or in any other way notify you if some variables or filters are missing, i.e. not passed to the `render` method.
+You can improve this situation by passing `strict_variables: true` and/or `strict_filters: true` options to the `render` method.
+When one of these options is set to true, all errors about undefined variables and undefined filters will be stored in `errors` array of a `Liquid::Template` instance.
+Here are some examples:
+
+```ruby
+template = Liquid::Template.parse("{{x}} {{y}} {{z.a}} {{z.b}}")
+template.render({ 'x' => 1, 'z' => { 'a' => 2 } }, { strict_variables: true })
+#=> '1  2 ' # when a variable is undefined, it's rendered as nil
+template.errors
+#=> [#<Liquid::UndefinedVariable: Liquid error: undefined variable y>, #<Liquid::UndefinedVariable: Liquid error: undefined variable b>]
+```
+
+```ruby
+template = Liquid::Template.parse("{{x | filter1 | upcase}}")
+template.render({ 'x' => 'foo' }, { strict_filters: true })
+#=> '' # when at least one filter in the filter chain is undefined, a whole expression is rendered as nil
+template.errors
+#=> [#<Liquid::UndefinedFilter: Liquid error: undefined filter filter1>]
+```
+
+If you want to raise on a first exception instead of pushing all of them in `errors`, you can use `render!` method:
+
+```ruby
+template = Liquid::Template.parse("{{x}} {{y}}")
+template.render!({ 'x' => 1}, { strict_variables: true })
+#=> Liquid::UndefinedVariable: Liquid error: undefined variable y
+```

Rakefile

@@ -1,77 +1,107 @@
+# frozen_string_literal: true
+
 require 'rake'
 require 'rake/testtask'
-$LOAD_PATH.unshift File.expand_path("../lib", __FILE__)
-require "liquid/version"
+$LOAD_PATH.unshift(File.expand_path('lib', __dir__))
+require 'liquid/version'
 
-task :default => 'test'
+task(default: %i[test rubocop])
 
-desc 'run test suite with default parser'
+desc('run test suite with default parser')
 Rake::TestTask.new(:base_test) do |t|
   t.libs << '.' << 'lib' << 'test'
   t.test_files = FileList['test/{integration,unit}/**/*_test.rb']
   t.verbose = false
 end
 
-desc 'run test suite with warn error mode'
+desc('run test suite with warn error mode')
 task :warn_test do
   ENV['LIQUID_PARSER_MODE'] = 'warn'
   Rake::Task['base_test'].invoke
 end
 
-desc 'runs test suite with both strict and lax parsers'
+task :rubocop do
+  if RUBY_ENGINE == 'ruby'
+    require 'rubocop/rake_task'
+    RuboCop::RakeTask.new
+  end
+end
+
+desc('runs test suite with both strict and lax parsers')
 task :test do
   ENV['LIQUID_PARSER_MODE'] = 'lax'
   Rake::Task['base_test'].invoke
+
   ENV['LIQUID_PARSER_MODE'] = 'strict'
   Rake::Task['base_test'].reenable
   Rake::Task['base_test'].invoke
+
+  if RUBY_ENGINE == 'ruby' || RUBY_ENGINE == 'truffleruby'
+
+    ENV['LIQUID_C'] = '1'
+
+    ENV['LIQUID_PARSER_MODE'] = 'lax'
+    Rake::Task['base_test'].reenable
+    Rake::Task['base_test'].invoke
+
+    ENV['LIQUID_PARSER_MODE'] = 'strict'
+    Rake::Task['base_test'].reenable
+    Rake::Task['base_test'].invoke
+  end
 end
 
-task :gem => :build
+task(gem: :build)
 task :build do
-  system "gem build liquid.gemspec"
+  system 'gem build liquid.gemspec'
 end
 
-task :install => :build do
+task install: :build do
   system "gem install liquid-#{Liquid::VERSION}.gem"
 end
 
-task :release => :build do
+task release: :build do
   system "git tag -a v#{Liquid::VERSION} -m 'Tagging #{Liquid::VERSION}'"
-  system "git push --tags"
+  system 'git push --tags'
   system "gem push liquid-#{Liquid::VERSION}.gem"
   system "rm liquid-#{Liquid::VERSION}.gem"
 end
 
 namespace :benchmark do
-
-  desc "Run the liquid benchmark with lax parsing"
+  desc 'Run the liquid benchmark with lax parsing'
   task :run do
-    ruby "./performance/benchmark.rb lax"
+    ruby './performance/benchmark.rb lax'
   end
 
-  desc "Run the liquid benchmark with strict parsing"
+  desc 'Run the liquid benchmark with strict parsing'
   task :strict do
-    ruby "./performance/benchmark.rb strict"
+    ruby './performance/benchmark.rb strict'
   end
 end
 
-
 namespace :profile do
-
-  desc "Run the liquid profile/performance coverage"
+  desc 'Run the liquid profile/performance coverage'
   task :run do
-    ruby "./performance/profile.rb"
+    ruby './performance/profile.rb'
   end
 
-  desc "Run the liquid profile/performance coverage with strict parsing"
+  desc 'Run the liquid profile/performance coverage with strict parsing'
   task :strict do
-    ruby "./performance/profile.rb strict"
+    ruby './performance/profile.rb strict'
   end
-
 end
 
-desc "Run example"
+namespace :memory_profile do
+  desc 'Run memory profiler'
+  task :run do
+    ruby './performance/memory_profile.rb'
+  end
+end
+
+desc('Run example')
 task :example do
-  ruby "-w -d -Ilib example/server/server.rb"
+  ruby '-w -d -Ilib example/server/server.rb'
+end
+
+task :console do
+  exec 'irb -I lib -r liquid'
 end

example/server/example_servlet.rb

@@ -1,10 +1,12 @@
+# frozen_string_literal: true
+
 module ProductsFilter
   def price(integer)
-    sprintf("$%.2d USD", integer / 100.0)
+    format('$%.2d USD', integer / 100.0)
   end
 
   def prettyprint(text)
-    text.gsub( /\*(.*)\*/, '<b>\1</b>' )
+    text.gsub(/\*(.*)\*/, '<b>\1</b>')
   end
 
   def count(array)
@@ -17,25 +19,28 @@ module ProductsFilter
 end
 
 class Servlet < LiquidServlet
-
   def index
     { 'date' => Time.now }
   end
 
   def products
-    { 'products' => products_list, 'description' => description, 'section' => 'Snowboards', 'cool_products' => true}
+    { 'products' => products_list, 'more_products' => more_products_list, 'description' => description, 'section' => 'Snowboards', 'cool_products' => true }
   end
 
   private
 
   def products_list
-    [{'name' => 'Arbor Draft', 'price' => 39900, 'description' => 'the *arbor draft* is a excellent product' },
-    {'name' => 'Arbor Element', 'price' => 40000, 'description' => 'the *arbor element* rocks for freestyling'},
-    {'name' => 'Arbor Diamond', 'price' => 59900, 'description' => 'the *arbor diamond* is a made up product because im obsessed with arbor and have no creativity'}]
+    [{ 'name' => 'Arbor Draft', 'price' => 39_900, 'description' => 'the *arbor draft* is a excellent product' },
+     { 'name' => 'Arbor Element', 'price' => 40_000, 'description' => 'the *arbor element* rocks for freestyling' },
+     { 'name' => 'Arbor Diamond', 'price' => 59_900, 'description' => 'the *arbor diamond* is a made up product because im obsessed with arbor and have no creativity' }]
+  end
+
+  def more_products_list
+    [{ 'name' => 'Arbor Catalyst', 'price' => 39_900, 'description' => 'the *arbor catalyst* is an advanced drop-through for freestyle and flatground performance and versatility' },
+     { 'name' => 'Arbor Fish', 'price' => 40_000, 'description' => 'the *arbor fish* is a compact pin that features an extended wheelbase and time-honored teardrop shape' }]
   end
 
   def description
-    "List of Products ~ This is a list of products with price and description."
+    'List of Products ~ This is a list of products with price and description.'
   end
-
 end

example/server/liquid_servlet.rb

@@ -1,28 +1,33 @@
-class LiquidServlet < WEBrick::HTTPServlet::AbstractServlet
+# frozen_string_literal: true
 
-  def do_GET(req, res)
+class LiquidServlet < WEBrick::HTTPServlet::AbstractServlet
+  def get(req, res)
     handle(:get, req, res)
   end
 
-  def do_POST(req, res)
+  def post(req, res)
     handle(:post, req, res)
   end
 
+  alias_method :do_GET, :get
+  alias_method :do_POST, :post
+
   private
 
-  def handle(type, req, res)
-    @request, @response = req, res
+  def handle(_type, req, res)
+    @request = req
+    @response = res
 
     @request.path_info =~ /(\w+)\z/
-    @action = $1 || 'index'
+    @action = Regexp.last_match(1) || 'index'
     @assigns = send(@action) if respond_to?(@action)
 
-    @response['Content-Type'] = "text/html"
+    @response['Content-Type'] = 'text/html'
     @response.status = 200
-    @response.body = Liquid::Template.parse(read_template).render(@assigns, :filters => [ProductsFilter])
+    @response.body = Liquid::Template.parse(read_template).render(@assigns, filters: [ProductsFilter])
   end
 
   def read_template(filename = @action)
-    File.read( File.dirname(__FILE__) + "/templates/#{filename}.liquid" )
+    File.read("#{__dir__}/templates/#{filename}.liquid")
   end
 end

example/server/server.rb

@@ -1,14 +1,14 @@
+# frozen_string_literal: true
+
 require 'webrick'
 require 'rexml/document'
 
-DIR = File.expand_path(File.dirname(__FILE__))
-
-require DIR + '/../../lib/liquid'
-require DIR + '/liquid_servlet'
-require DIR + '/example_servlet'
+require_relative '../../lib/liquid'
+require_relative 'liquid_servlet'
+require_relative 'example_servlet'
 
 # Setup webrick
-server = WEBrick::HTTPServer.new( :Port => ARGV[1] || 3000 )
+server = WEBrick::HTTPServer.new(Port: ARGV[1] || 3000)
 server.mount('/', Servlet)
-trap("INT"){ server.shutdown }
+trap('INT') { server.shutdown }
 server.start

example/server/templates/products.liquid

@@ -16,12 +16,12 @@
   </head>
 
   <body>
-
+    {% assign all_products = products | concat: more_products  %}
     <h1>{{ description | split: '~' | first }}</h1>
 
     <h2>{{ description | split: '~' | last }}</h2>
 
-    <h2>There are currently {{products | count}} products in the {{section}} catalog</h2>
+    <h2>There are currently {{all_products | count}} products in the {{section}} catalog</h2>
 
     {% if cool_products %}
       Cool products :)
@@ -31,7 +31,7 @@
 
     <ul id="products">
 
-      {% for product in products %}
+      {% for product in all_products %}
         <li>
           <h2>{{product.name}}</h2>
           Only {{product.price | price }}

lib/liquid.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright (c) 2005 Tobias Luetke
 #
 # Permission is hereby granted, free of charge, to any person obtaining
@@ -20,50 +22,61 @@
 # WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 
 module Liquid
-  FilterSeparator             = /\|/
-  ArgumentSeparator           = ','.freeze
-  FilterArgumentSeparator     = ':'.freeze
-  VariableAttributeSeparator  = '.'.freeze
-  TagStart                    = /\{\%/
-  TagEnd                      = /\%\}/
-  VariableSignature           = /\(?[\w\-\.\[\]]\)?/
-  VariableSegment             = /[\w\-]/
-  VariableStart               = /\{\{/
-  VariableEnd                 = /\}\}/
-  VariableIncompleteEnd       = /\}\}?/
-  QuotedString                = /"[^"]*"|'[^']*'/
-  QuotedFragment              = /#{QuotedString}|(?:[^\s,\|'"]|#{QuotedString})+/o
-  TagAttributes               = /(\w+)\s*\:\s*(#{QuotedFragment})/o
-  AnyStartingTag              = /\{\{|\{\%/
-  PartialTemplateParser       = /#{TagStart}.*?#{TagEnd}|#{VariableStart}.*?#{VariableIncompleteEnd}/om
-  TemplateParser              = /(#{PartialTemplateParser}|#{AnyStartingTag})/om
-  VariableParser              = /\[[^\]]+\]|#{VariableSegment}+\??/o
+  FILTER_SEPARATOR = /\|/.freeze
+  ARGUMENT_SEPARATOR = ','
+  FILTER_ARGUMENT_SEPARATOR = ':'
+  VARIABLE_ATTRIBUTE_SEPARATOR = '.'
+  WHITESPACE_CONTROL = '-'
+  TAG_START = /\{\%/.freeze
+  TAG_END = /\%\}/.freeze
+  VARIABLE_SIGNATURE = /\(?[\w\-\.\[\]]\)?/.freeze
+  VARIABLE_SEGMENT = /[\w\-]/.freeze
+  VARIABLE_START = /\{\{/.freeze
+  VARIABLE_END = /\}\}/.freeze
+  VARIABLE_INCOMPLETE_END = /\}\}?/.freeze
+  QUOTED_STRING = /"[^"]*"|'[^']*'/.freeze
+  QUOTED_FRAGMENT = /#{QUOTED_STRING}|(?:[^\s,\|'"]|#{QUOTED_STRING})+/o.freeze
+  TAG_ATTRIBUTES = /(\w+)\s*\:\s*(#{QUOTED_FRAGMENT})/o.freeze
+  ANY_STARTING_TAG = /#{TAG_START}|#{VARIABLE_START}/o.freeze
+  PARTIAL_TEMPLATE_PARSER = /#{TAG_START}.*?#{TAG_END}|#{VARIABLE_START}.*?#{VARIABLE_INCOMPLETE_END}/om.freeze
+  TEMPLATE_PARSER = /(#{PARTIAL_TEMPLATE_PARSER}|#{ANY_STARTING_TAG})/om.freeze
+  VARIABLE_PARSER = /\[[^\]]+\]|#{VARIABLE_SEGMENT}+\??/o.freeze
 
   singleton_class.send(:attr_accessor, :cache_classes)
   self.cache_classes = true
 end
 
-require "liquid/version"
+require 'liquid/version'
+require 'liquid/parse_tree_visitor'
 require 'liquid/lexer'
 require 'liquid/parser'
 require 'liquid/i18n'
 require 'liquid/drop'
+require 'liquid/tablerowloop_drop'
+require 'liquid/forloop_drop'
 require 'liquid/extensions'
 require 'liquid/errors'
 require 'liquid/interrupts'
 require 'liquid/strainer'
+require 'liquid/expression'
 require 'liquid/context'
+require 'liquid/parser_switching'
 require 'liquid/tag'
 require 'liquid/block'
+require 'liquid/block_body'
 require 'liquid/document'
 require 'liquid/variable'
+require 'liquid/variable_lookup'
+require 'liquid/range_lookup'
 require 'liquid/file_system'
+require 'liquid/resource_limits'
 require 'liquid/template'
 require 'liquid/standardfilters'
 require 'liquid/condition'
-require 'liquid/module_ex'
 require 'liquid/utils'
+require 'liquid/tokenizer'
+require 'liquid/parse_context'
 
 # Load all the tags of the standard library
 #
-Dir[File.dirname(__FILE__) + '/liquid/tags/*.rb'].each { |f| require f }
+Dir["#{__dir__}/liquid/tags/*.rb"].each { |f| require f }

lib/liquid/block.rb

@@ -1,93 +1,44 @@
+# frozen_string_literal: true
+
 module Liquid
   class Block < Tag
-    FullToken         = /\A#{TagStart}\s*(\w+)\s*(.*)?#{TagEnd}\z/om
-    ContentOfVariable = /\A#{VariableStart}(.*)#{VariableEnd}\z/om
-    TAGSTART = "{%".freeze
-    VARSTART = "{{".freeze
+    MAX_DEPTH = 100
+
+    def initialize(tag_name, markup, options)
+      super
+      @blank = true
+    end
+
+    def parse(tokens)
+      @body = BlockBody.new
+      while parse_body(@body, tokens)
+      end
+    end
+
+    # For backwards compatibility
+    def render(context)
+      @body.render(context)
+    end
 
     def blank?
       @blank
     end
 
-    def parse(tokens)
-      @blank = true
-      @nodelist ||= []
-      @nodelist.clear
-
-      # All child tags of the current block.
-      @children = []
-
-      while token = tokens.shift
-        unless token.empty?
-          case
-          when token.start_with?(TAGSTART)
-            if token =~ FullToken
-
-              # if we found the proper block delimiter just end parsing here and let the outer block
-              # proceed
-              if block_delimiter == $1
-                end_tag
-                return
-              end
-
-              # fetch the tag from registered blocks
-              if tag = Template.tags[$1]
-                new_tag = tag.parse($1, $2, tokens, @options)
-                @blank &&= new_tag.blank?
-                @nodelist << new_tag
-                @children << new_tag
-              else
-                # this tag is not registered with the system
-                # pass it to the current block for special handling or error reporting
-                unknown_tag($1, $2, tokens)
-              end
-            else
-              raise SyntaxError.new(options[:locale].t("errors.syntax.tag_termination".freeze, :token => token, :tag_end => TagEnd.inspect))
-            end
-          when token.start_with?(VARSTART)
-            new_var = create_variable(token)
-            @nodelist << new_var
-            @children << new_var
-            @blank = false
-          else
-            @nodelist << token
-            @blank &&= (token =~ /\A\s*\z/)
-          end
-        end
-      end
-
-      # Make sure that it's ok to end parsing in the current block.
-      # Effectively this method will throw an exception unless the current block is
-      # of type Document
-      assert_missing_delimitation!
+    def nodelist
+      @body.nodelist
     end
 
-    # warnings of this block and all sub-tags
-    def warnings
-      all_warnings = []
-      all_warnings.concat(@warnings) if @warnings
-
-      (@children || []).each do |node|
-        all_warnings.concat(node.warnings || [])
-      end
-
-      all_warnings
-    end
-
-    def end_tag
-    end
-
-    def unknown_tag(tag, params, tokens)
-      case tag
-      when 'else'.freeze
-        raise SyntaxError.new(options[:locale].t("errors.syntax.unexpected_else".freeze,
-                                                 :block_name => block_name))
-      when 'end'.freeze
-        raise SyntaxError.new(options[:locale].t("errors.syntax.invalid_delimiter".freeze,
-                                                 :block_name => block_name,
-                                                 :block_delimiter => block_delimiter))
+    def unknown_tag(tag, _params, _tokens)
+      if tag == 'else'
+        raise SyntaxError, parse_context.locale.t('errors.syntax.unexpected_else',
+                                                  block_name: block_name)
+      elsif tag.start_with?('end')
+        raise SyntaxError, parse_context.locale.t('errors.syntax.invalid_delimiter',
+                                                  tag: tag,
+                                                  block_name: block_name,
+                                                  block_delimiter: block_delimiter)
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.unknown_tag".freeze, :tag => tag))
+        raise SyntaxError, parse_context.locale.t('errors.syntax.unknown_tag', tag: tag)
       end
     end
 
@@ -99,58 +50,28 @@ module Liquid
       @block_delimiter ||= "end#{block_name}"
     end
 
-    def create_variable(token)
-      token.scan(ContentOfVariable) do |content|
-        return Variable.new(content.first, @options)
-      end
-      raise SyntaxError.new(options[:locale].t("errors.syntax.variable_termination".freeze, :token => token, :tag_end => VariableEnd.inspect))
-    end
-
-    def render(context)
-      render_all(@nodelist, context)
-    end
-
     protected
 
-    def assert_missing_delimitation!
-      raise SyntaxError.new(options[:locale].t("errors.syntax.tag_never_closed".freeze, :block_name => block_name))
-    end
+    def parse_body(body, tokens)
+      raise StackLevelError, 'Nesting too deep' if parse_context.depth >= MAX_DEPTH
 
-    def render_all(list, context)
-      output = []
-      context.resource_limits[:render_length_current] = 0
-      context.resource_limits[:render_score_current] += list.length
+      parse_context.depth += 1
+      begin
+        body.parse(tokens, parse_context) do |end_tag_name, end_tag_params|
+          @blank &&= body.blank?
 
-      list.each do |token|
-        # Break out if we have any unhanded interrupts.
-        break if context.has_interrupt?
+          return false if end_tag_name == block_delimiter
+          raise SyntaxError, parse_context.locale.t('errors.syntax.tag_never_closed', block_name: block_name) unless end_tag_name
 
-        begin
-          # If we get an Interrupt that means the block must stop processing. An
-          # Interrupt is any command that stops block execution such as {% break %}
-          # or {% continue %}
-          if token.is_a? Continue or token.is_a? Break
-            context.push_interrupt(token.interrupt)
-            break
-          end
-
-          token_output = (token.respond_to?(:render) ? token.render(context) : token)
-          context.increment_used_resources(:render_length_current, token_output)
-          if context.resource_limits_reached?
-            context.resource_limits[:reached] = true
-            raise MemoryError.new("Memory limits exceeded".freeze)
-          end
-          unless token.is_a?(Block) && token.blank?
-            output << token_output
-          end
-        rescue MemoryError => e
-          raise e
-        rescue ::StandardError => e
-          output << (context.handle_error(e))
+          # this tag is not registered with the system
+          # pass it to the current block for special handling or error reporting
+          unknown_tag(end_tag_name, end_tag_params, tokens)
         end
+      ensure
+        parse_context.depth -= 1
       end
 
-      output.join
+      true
     end
   end
 end

lib/liquid/block_body.rb

@@ -0,0 +1,142 @@
+# frozen_string_literal: true
+
+module Liquid
+  class BlockBody
+    FULL_TOKEN = /\A#{TAG_START}#{WHITESPACE_CONTROL}?\s*(\w+)\s*(.*?)#{WHITESPACE_CONTROL}?#{TAG_END}\z/om.freeze
+    CONTENT_OF_VARIABLE = /\A#{VARIABLE_START}#{WHITESPACE_CONTROL}?(.*?)#{WHITESPACE_CONTROL}?#{VARIABLE_END}\z/om.freeze
+    WHITESPACE_OR_NOTHING = /\A\s*\z/.freeze
+    TAG_START = '{%'
+    VAR_START = '{{'
+
+    attr_reader :nodelist
+
+    def initialize
+      @nodelist = []
+      @blank = true
+    end
+
+    def parse(tokenizer, parse_context)
+      parse_context.line_number = tokenizer.line_number
+      while (token = tokenizer.shift)
+        next if token.empty?
+
+        case
+        when token.start_with?(TAG_START)
+          whitespace_handler(token, parse_context)
+          raise_missing_tag_terminator(token, parse_context) unless token =~ FULL_TOKEN
+          tag_name = Regexp.last_match(1)
+          markup = Regexp.last_match(2)
+          # fetch the tag from registered blocks
+          unless (tag = registered_tags[tag_name])
+            # end parsing if we reach an unknown tag and let the caller decide
+            # determine how to proceed
+            return yield tag_name, markup
+          end
+
+          new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
+          @blank &&= new_tag.blank?
+          @nodelist << new_tag
+        when token.start_with?(VAR_START)
+          whitespace_handler(token, parse_context)
+          @nodelist << create_variable(token, parse_context)
+          @blank = false
+        else
+          token.lstrip! if parse_context.trim_whitespace
+          parse_context.trim_whitespace = false
+          @nodelist << token
+          @blank &&= token.match?(WHITESPACE_OR_NOTHING)
+        end
+        parse_context.line_number = tokenizer.line_number
+      end
+
+      yield nil, nil
+    end
+
+    def whitespace_handler(token, parse_context)
+      if token[2] == WHITESPACE_CONTROL
+        previous_token = @nodelist.last
+        previous_token.rstrip! if previous_token.is_a?(String)
+      end
+      parse_context.trim_whitespace = (token[-3] == WHITESPACE_CONTROL)
+    end
+
+    def blank?
+      @blank
+    end
+
+    def render(context)
+      render_to_output_buffer(context, +'')
+    end
+
+    def render_to_output_buffer(context, output)
+      context.resource_limits.render_score += @nodelist.length
+
+      idx = 0
+      while (node = @nodelist[idx])
+        previous_output_size = output.bytesize
+
+        case node
+        when String
+          output << node
+        when Variable
+          render_node(context, output, node)
+        when Block
+          render_node(context, node.blank? ? +'' : output, node)
+          break if context.interrupt? # might have happened in a for-block
+        when Continue, Break
+          # If we get an Interrupt that means the block must stop processing. An
+          # Interrupt is any command that stops block execution such as {% break %}
+          # or {% continue %}
+          context.push_interrupt(node.interrupt)
+          break
+        else # Other non-Block tags
+          render_node(context, output, node)
+          break if context.interrupt? # might have happened through an include
+        end
+        idx += 1
+
+        raise_if_resource_limits_reached(context, output.bytesize - previous_output_size)
+      end
+
+      output
+    end
+
+    private
+
+    def render_node(context, output, node)
+      node.render_to_output_buffer(context, output)
+    rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
+      context.handle_error(e, node.line_number)
+    rescue ::StandardError => e
+      line_number = node.is_a?(String) ? nil : node.line_number
+      output << context.handle_error(e, line_number)
+    end
+
+    def raise_if_resource_limits_reached(context, length)
+      context.resource_limits.render_length += length
+      return unless context.resource_limits.reached?
+
+      raise MemoryError, 'Memory limits exceeded'
+    end
+
+    def create_variable(token, parse_context)
+      token.scan(CONTENT_OF_VARIABLE) do |content|
+        markup = content.first
+        return Variable.new(markup, parse_context)
+      end
+      raise_missing_variable_terminator(token, parse_context)
+    end
+
+    def raise_missing_tag_terminator(token, parse_context)
+      raise SyntaxError, parse_context.locale.t('errors.syntax.tag_termination', token: token, tag_end: TAG_END.inspect)
+    end
+
+    def raise_missing_variable_terminator(token, parse_context)
+      raise SyntaxError, parse_context.locale.t('errors.syntax.variable_termination', token: token, tag_end: VARIABLE_END.inspect)
+    end
+
+    def registered_tags
+      Template.tags
+    end
+  end
+end

lib/liquid/condition.rb

@@ -1,55 +1,74 @@
+# frozen_string_literal: true
+
 module Liquid
   # Container for liquid nodes which conveniently wraps decision making logic
   #
   # Example:
   #
-  #   c = Condition.new('1', '==', '1')
+  #   c = Condition.new(1, '==', 1)
   #   c.evaluate #=> true
   #
   class Condition #:nodoc:
-    @@operators = {
-      '=='.freeze => lambda { |cond, left, right|  cond.send(:equal_variables, left, right) },
-      '!='.freeze => lambda { |cond, left, right| !cond.send(:equal_variables, left, right) },
-      '<>'.freeze => lambda { |cond, left, right| !cond.send(:equal_variables, left, right) },
-      '<'.freeze  => :<,
-      '>'.freeze  => :>,
-      '>='.freeze => :>=,
-      '<='.freeze => :<=,
-      'contains'.freeze => lambda { |cond, left, right| left && right ? left.include?(right) : false }
+    @operators = {
+      '==' => ->(cond, left, right) {  cond.send(:equal_variables, left, right) },
+      '!=' => ->(cond, left, right) { !cond.send(:equal_variables, left, right) },
+      '<>' => ->(cond, left, right) { !cond.send(:equal_variables, left, right) },
+      '<' => :<,
+      '>' => :>,
+      '>=' => :>=,
+      '<=' => :<=,
+      'contains' => lambda do |_cond, left, right|
+        if left && right && left.respond_to?(:include?)
+          right = right.to_s if left.is_a?(String)
+          left.include?(right)
+        else
+          false
+        end
+      end,
     }
 
-    def self.operators
-      @@operators
+    class << self
+      attr_accessor :operators
     end
 
-    attr_reader :attachment
+    attr_reader :attachment, :child_condition
     attr_accessor :left, :operator, :right
 
     def initialize(left = nil, operator = nil, right = nil)
-      @left, @operator, @right = left, operator, right
-      @child_relation  = nil
+      @left = left
+      @operator = operator
+      @right = right
+      @child_relation = nil
       @child_condition = nil
     end
 
     def evaluate(context = Context.new)
-      result = interpret_condition(left, right, operator, context)
+      condition = self
+      result = nil
+      loop do
+        result = interpret_condition(condition.left, condition.right, condition.operator, context)
 
-      case @child_relation
-      when :or
-        result || @child_condition.evaluate(context)
-      when :and
-        result && @child_condition.evaluate(context)
-      else
-        result
+        case condition.child_relation
+        when :or
+          break if result
+        when :and
+          break unless result
+        else
+          break
+        end
+        condition = condition.child_condition
       end
+      result
     end
 
     def or(condition)
-      @child_relation, @child_condition = :or, condition
+      @child_relation = :or
+      @child_condition = condition
     end
 
     def and(condition)
-      @child_relation, @child_condition = :and, condition
+      @child_relation = :and
+      @child_condition = condition
     end
 
     def attach(attachment)
@@ -61,23 +80,27 @@ module Liquid
     end
 
     def inspect
-      "#<Condition #{[@left, @operator, @right].compact.join(' '.freeze)}>"
+      "#<Condition #{[@left, @operator, @right].compact.join(' ')}>"
     end
 
+    protected
+
+    attr_reader :child_relation
+
     private
 
     def equal_variables(left, right)
-      if left.is_a?(Symbol)
-        if right.respond_to?(left)
-          return right.send(left.to_s)
+      if left.is_a?(Liquid::Expression::MethodLiteral)
+        if right.respond_to?(left.method_name)
+          return right.send(left.method_name)
         else
           return nil
         end
       end
 
-      if right.is_a?(Symbol)
-        if left.respond_to?(right)
-          return left.send(right.to_s)
+      if right.is_a?(Liquid::Expression::MethodLiteral)
+        if left.respond_to?(right.method_name)
+          return left.send(right.method_name)
         else
           return nil
         end
@@ -90,35 +113,41 @@ module Liquid
       # If the operator is empty this means that the decision statement is just
       # a single variable. We can just poll this variable from the context and
       # return this as the result.
-      return context[left] if op == nil
+      return context.evaluate(left) if op.nil?
 
-      left, right = context[left], context[right]
+      left = context.evaluate(left)
+      right = context.evaluate(right)
 
-      operation = self.class.operators[op] || raise(Liquid::ArgumentError.new("Unknown operator #{op}"))
+      operation = self.class.operators[op] || raise(Liquid::ArgumentError, "Unknown operator #{op}")
 
       if operation.respond_to?(:call)
         operation.call(self, left, right)
-      elsif left.respond_to?(operation) and right.respond_to?(operation)
+      elsif left.respond_to?(operation) && right.respond_to?(operation) && !left.is_a?(Hash) && !right.is_a?(Hash)
         begin
           left.send(operation, right)
         rescue ::ArgumentError => e
-          raise Liquid::ArgumentError.new(e.message)
+          raise Liquid::ArgumentError, e.message
         end
-      else
-        nil
+      end
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.left, @node.right,
+          @node.child_condition, @node.attachment
+        ].compact
       end
     end
   end
 
-
   class ElseCondition < Condition
     def else?
       true
     end
 
-    def evaluate(context)
+    def evaluate(_context)
       true
     end
   end
-
 end

lib/liquid/context.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # Context keeps the variable stack and resolves variables, as well as keywords
   #
   #   context['variable'] = 'testing'
@@ -14,39 +15,30 @@ module Liquid
   #   context['bob']  #=> nil  class Context
   class Context
     attr_reader :scopes, :errors, :registers, :environments, :resource_limits
-    attr_accessor :exception_handler
+    attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
-    SQUARE_BRACKETED = /\A\[(.*)\]\z/m
-
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = {})
-      @environments    = [environments].flatten
-      @scopes          = [(outer_scope || {})]
-      @registers       = registers
-      @errors          = []
-      @resource_limits = (resource_limits || {}).merge!({ :render_score_current => 0, :assign_score_current => 0 })
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil)
+      @environments     = [environments].flatten
+      @scopes           = [(outer_scope || {})]
+      @registers        = registers
+      @errors           = []
+      @partial          = false
+      @strict_variables = false
+      @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
       squash_instance_assigns_with_environments
 
-      if rethrow_errors
-        self.exception_handler = ->(e) { true }
-      end
+      @this_stack_used = false
+
+      self.exception_renderer = Template.default_exception_renderer
+      self.exception_renderer = ->(_e) { raise } if rethrow_errors
 
       @interrupts = []
       @filters = []
-      @parsed_variables = Hash.new{ |cache, markup| cache[markup] = variable_parse(markup) } 
+      @global_filter = nil
     end
 
-    def increment_used_resources(key, obj)
-      @resource_limits[key] += if obj.kind_of?(String) || obj.kind_of?(Array) || obj.kind_of?(Hash)
-        obj.length
-      else
-        1
-      end
-    end
-
-    def resource_limits_reached?
-      (@resource_limits[:render_length_limit] && @resource_limits[:render_length_current] > @resource_limits[:render_length_limit]) ||
-      (@resource_limits[:render_score_limit]  && @resource_limits[:render_score_current]  > @resource_limits[:render_score_limit] ) ||
-      (@resource_limits[:assign_score_limit]  && @resource_limits[:assign_score_current]  > @resource_limits[:assign_score_limit] )
+    def warnings
+      @warnings ||= []
     end
 
     def strainer
@@ -59,25 +51,16 @@ module Liquid
     # for that
     def add_filters(filters)
       filters = [filters].flatten.compact
-      filters.each do |f|
-        raise ArgumentError, "Expected module but got: #{f.class}" unless f.is_a?(Module)
-        Strainer.add_known_filter(f)
-      end
+      @filters += filters
+      @strainer = nil
+    end
 
-      # If strainer is already setup then there's no choice but to use a runtime
-      # extend call. If strainer is not yet created, we can utilize strainers
-      # cached class based API, which avoids busting the method cache.
-      if @strainer
-        filters.each do |f|
-          strainer.extend(f)
-        end
-      else
-        @filters.concat filters
-      end
+    def apply_global_filter(obj)
+      global_filter.nil? ? obj : global_filter.call(obj)
     end
 
     # are there any not handled interrupts?
-    def has_interrupt?
+    def interrupt?
       !@interrupts.empty?
     end
 
@@ -91,27 +74,22 @@ module Liquid
       @interrupts.pop
     end
 
-    def handle_error(e)
+    def handle_error(e, line_number = nil)
+      e = internal_error unless e.is_a?(Liquid::Error)
+      e.template_name ||= template_name
+      e.line_number ||= line_number
       errors.push(e)
-
-      raise if exception_handler && exception_handler.call(e)
-
-      case e
-      when SyntaxError
-        "Liquid syntax error: #{e.message}"
-      else
-        "Liquid error: #{e.message}"
-      end
+      exception_renderer.call(e).to_s
     end
 
     def invoke(method, *args)
-      strainer.invoke(method, *args)
+      strainer.invoke(method, *args).to_liquid
     end
 
     # Push new local scope on the stack. use <tt>Context#stack</tt> instead
-    def push(new_scope={})
+    def push(new_scope = {})
       @scopes.unshift(new_scope)
-      raise StackLevelError, "Nesting too deep".freeze if @scopes.length > 100
+      raise StackLevelError, 'Nesting too deep' if @scopes.length > Block::MAX_DEPTH
     end
 
     # Merge a hash of variables in the current local scope
@@ -122,6 +100,7 @@ module Liquid
     # Pop from the stack. use <tt>Context#stack</tt> instead
     def pop
       raise ContextError if @scopes.size == 1
+
       @scopes.shift
     end
 
@@ -133,11 +112,19 @@ module Liquid
     #   end
     #
     #   context['var]  #=> nil
-    def stack(new_scope={})
-      push(new_scope)
+    def stack(new_scope = nil)
+      old_stack_used = @this_stack_used
+      if new_scope
+        push(new_scope)
+        @this_stack_used = true
+      else
+        @this_stack_used = false
+      end
+
       yield
     ensure
-      pop
+      pop if @this_stack_used
+      @this_stack_used = old_stack_used
     end
 
     def clear_instance_assigns
@@ -146,161 +133,93 @@ module Liquid
 
     # Only allow String, Numeric, Hash, Array, Proc, Boolean or <tt>Liquid::Drop</tt>
     def []=(key, value)
+      unless @this_stack_used
+        @this_stack_used = true
+        push({})
+      end
       @scopes[0][key] = value
     end
 
-    def [](key)
-      resolve(key)
+    # Look up variable, either resolve directly after considering the name. We can directly handle
+    # Strings, digits, floats and booleans (true,false).
+    # If no match is made we lookup the variable in the current scope and
+    # later move up to the parent blocks to see if we can resolve the variable somewhere up the tree.
+    # Some special keywords return symbols. Those symbols are to be called on the rhs object in expressions
+    #
+    # Example:
+    #   products == empty #=> products.empty?
+    def [](expression)
+      evaluate(Expression.parse(expression))
     end
 
-    def has_key?(key)
-      resolve(key) != nil
+    def key?(key)
+      self[key] != nil
+    end
+
+    def evaluate(object)
+      object.respond_to?(:evaluate) ? object.evaluate(self) : object
+    end
+
+    # Fetches an object starting at the local scope and then moving up the hierachy
+    def find_variable(key, raise_on_not_found: true)
+      # This was changed from find() to find_index() because this is a very hot
+      # path and find_index() is optimized in MRI to reduce object allocation
+      index = @scopes.find_index { |s| s.key?(key) }
+      scope = @scopes[index] if index
+
+      variable = nil
+
+      if scope.nil?
+        @environments.each do |e|
+          variable = lookup_and_evaluate(e, key, raise_on_not_found: raise_on_not_found)
+          # When lookup returned a value OR there is no value but the lookup also did not raise
+          # then it is the value we are looking for.
+          if !variable.nil? || @strict_variables && raise_on_not_found
+            scope = e
+            break
+          end
+        end
+      end
+
+      scope ||= @environments.last || @scopes.last
+      variable ||= lookup_and_evaluate(scope, key, raise_on_not_found: raise_on_not_found)
+
+      variable = variable.to_liquid
+      variable.context = self if variable.respond_to?(:context=)
+
+      variable
+    end
+
+    def lookup_and_evaluate(obj, key, raise_on_not_found: true)
+      raise Liquid::UndefinedVariable, "undefined variable #{key}" if @strict_variables && raise_on_not_found && obj.respond_to?(:key?) && !obj.key?(key)
+
+      value = obj[key]
+
+      if value.is_a?(Proc) && obj.respond_to?(:[]=)
+        obj[key] = value.arity == 0 ? value.call : value.call(self)
+      else
+        value
+      end
     end
 
     private
-      LITERALS = {
-        nil => nil, 'nil'.freeze => nil, 'null'.freeze => nil, ''.freeze => nil,
-        'true'.freeze  => true,
-        'false'.freeze => false,
-        'blank'.freeze => :blank?,
-        'empty'.freeze => :empty?
-      }
 
-      # Look up variable, either resolve directly after considering the name. We can directly handle
-      # Strings, digits, floats and booleans (true,false).
-      # If no match is made we lookup the variable in the current scope and
-      # later move up to the parent blocks to see if we can resolve the variable somewhere up the tree.
-      # Some special keywords return symbols. Those symbols are to be called on the rhs object in expressions
-      #
-      # Example:
-      #   products == empty #=> products.empty?
-      def resolve(key)
-        if LITERALS.key?(key)
-          LITERALS[key]
-        else
-          case key
-          when /\A'(.*)'\z/m # Single quoted strings
-            $1
-          when /\A"(.*)"\z/m # Double quoted strings
-            $1
-          when /\A(-?\d+)\z/ # Integer and floats
-            $1.to_i
-          when /\A\((\S+)\.\.(\S+)\)\z/ # Ranges
-            (resolve($1).to_i..resolve($2).to_i)
-          when /\A(-?\d[\d\.]+)\z/ # Floats
-            $1.to_f
-          else
-            variable(key)
+    def internal_error
+      # raise and catch to set backtrace and cause on exception
+      raise Liquid::InternalError, 'internal'
+    rescue Liquid::InternalError => e
+      e
+    end
+
+    def squash_instance_assigns_with_environments
+      @scopes.last.each_key do |k|
+        @environments.each do |env|
+          if env.key?(k)
+            scopes.last[k] = lookup_and_evaluate(env, k)
+            break
           end
         end
       end
-
-      # Fetches an object starting at the local scope and then moving up the hierachy
-      def find_variable(key)
-
-        # This was changed from find() to find_index() because this is a very hot
-        # path and find_index() is optimized in MRI to reduce object allocation
-        index = @scopes.find_index { |s| s.has_key?(key) }
-        scope = @scopes[index] if index
-
-        variable = nil
-
-        if scope.nil?
-          @environments.each do |e|
-            variable = lookup_and_evaluate(e, key)
-            unless variable.nil?
-              scope = e
-              break
-            end
-          end
-        end
-
-        scope     ||= @environments.last || @scopes.last
-        variable  ||= lookup_and_evaluate(scope, key)
-
-        variable = variable.to_liquid
-        variable.context = self if variable.respond_to?(:context=)
-
-        return variable
-      end
-
-      def variable_parse(markup)
-        parts = markup.scan(VariableParser)
-        needs_resolution = false
-        if parts.first =~ SQUARE_BRACKETED 
-          needs_resolution = true
-          parts[0] = $1
-        end
-        {:first => parts.shift, :needs_resolution => needs_resolution, :rest => parts} 
-      end
-
-      # Resolves namespaced queries gracefully.
-      #
-      # Example
-      #  @context['hash'] = {"name" => 'tobi'}
-      #  assert_equal 'tobi', @context['hash.name']
-      #  assert_equal 'tobi', @context['hash["name"]']
-      def variable(markup)
-        parts = @parsed_variables[markup]
-
-        first_part = parts[:first] 
-        if parts[:needs_resolution]
-          first_part = resolve(parts[:first])
-        end
-
-        if object = find_variable(first_part)
-
-          parts[:rest].each do |part|
-            part = resolve($1) if part_resolved = (part =~ SQUARE_BRACKETED)
-
-            # If object is a hash- or array-like object we look for the
-            # presence of the key and if its available we return it
-            if object.respond_to?(:[]) and
-              ((object.respond_to?(:has_key?) and object.has_key?(part)) or
-               (object.respond_to?(:fetch) and part.is_a?(Integer)))
-
-              # if its a proc we will replace the entry with the proc
-              res = lookup_and_evaluate(object, part)
-              object = res.to_liquid
-
-              # Some special cases. If the part wasn't in square brackets and
-              # no key with the same name was found we interpret following calls
-              # as commands and call them on the current object
-            elsif !part_resolved and object.respond_to?(part) and ['size'.freeze, 'first'.freeze, 'last'.freeze].include?(part)
-
-              object = object.send(part.intern).to_liquid
-
-              # No key was present with the desired value and it wasn't one of the directly supported
-              # keywords either. The only thing we got left is to return nil
-            else
-              return nil
-            end
-
-            # If we are dealing with a drop here we have to
-            object.context = self if object.respond_to?(:context=)
-          end
-        end
-
-        object
-      end # variable
-
-      def lookup_and_evaluate(obj, key)
-        if (value = obj[key]).is_a?(Proc) && obj.respond_to?(:[]=)
-          obj[key] = (value.arity == 0) ? value.call : value.call(self)
-        else
-          value
-        end
-      end # lookup_and_evaluate
-
-      def squash_instance_assigns_with_environments
-        @scopes.last.each_key do |k|
-          @environments.each do |env|
-            if env.has_key?(k)
-              scopes.last[k] = lookup_and_evaluate(env, k)
-              break
-            end
-          end
-        end
-      end # squash_instance_assigns_with_environments
+    end # squash_instance_assigns_with_environments
   end # Context
 end # Liquid

lib/liquid/document.rb

@@ -1,17 +1,29 @@
+# frozen_string_literal: true
+
 module Liquid
-  class Document < Block
-    def self.parse(tokens, options={})
-      # we don't need markup to open this block
-      super(nil, nil, tokens, options)
+  class Document < BlockBody
+    def self.parse(tokens, parse_context)
+      doc = new
+      doc.parse(tokens, parse_context)
+      doc
     end
 
-    # There isn't a real delimiter
-    def block_delimiter
-      []
+    def parse(tokens, parse_context)
+      super do |end_tag_name, _end_tag_params|
+        unknown_tag(end_tag_name, parse_context) if end_tag_name
+      end
+    rescue SyntaxError => e
+      e.line_number ||= parse_context.line_number
+      raise
     end
 
-    # Document blocks don't need to be terminated since they are not actually opened
-    def assert_missing_delimitation!
+    def unknown_tag(tag, parse_context)
+      case tag
+      when 'else', 'end'
+        raise SyntaxError, parse_context.locale.t('errors.syntax.unexpected_outer_tag', tag: tag)
+      else
+        raise SyntaxError, parse_context.locale.t('errors.syntax.unknown_tag', tag: tag)
+      end
     end
   end
 end

lib/liquid/drop.rb

@@ -1,7 +1,8 @@
+# frozen_string_literal: true
+
 require 'set'
 
 module Liquid
-
   # A drop in liquid is a class which allows you to export DOM like things to liquid.
   # Methods of drops are callable.
   # The main use for liquid drops is to implement lazy loaded objects.
@@ -19,28 +20,28 @@ module Liquid
   #   tmpl = Liquid::Template.parse( ' {% for product in product.top_sales %} {{ product.name }} {%endfor%} '  )
   #   tmpl.render('product' => ProductDrop.new ) # will invoke top_sales query.
   #
-  # Your drop can either implement the methods sans any parameters or implement the before_method(name) method which is a
-  # catch all.
+  # Your drop can either implement the methods sans any parameters
+  # or implement the liquid_method_missing(name) method which is a catch all.
   class Drop
     attr_writer :context
 
-    EMPTY_STRING = ''.freeze
-
     # Catch all for the method
-    def before_method(method)
-      nil
+    def liquid_method_missing(method)
+      return nil unless @context&.strict_variables
+
+      raise Liquid::UndefinedDropMethod, "undefined method #{method}"
     end
 
     # called by liquid to invoke a drop
     def invoke_drop(method_or_key)
-      if method_or_key && method_or_key != EMPTY_STRING && self.class.invokable?(method_or_key)
+      if self.class.invokable?(method_or_key)
         send(method_or_key)
       else
-        before_method(method_or_key)
+        liquid_method_missing(method_or_key)
       end
     end
 
-    def has_key?(name)
+    def key?(_name)
       true
     end
 
@@ -56,22 +57,25 @@ module Liquid
       self.class.name
     end
 
-    alias :[] :invoke_drop
-
-    private
+    alias_method :[], :invoke_drop
 
     # Check for method existence without invoking respond_to?, which creates symbols
     def self.invokable?(method_name)
-      unless @invokable_methods
+      invokable_methods.include?(method_name.to_s)
+    end
+
+    def self.invokable_methods
+      @invokable_methods ||= begin
         blacklist = Liquid::Drop.public_instance_methods + [:each]
+
         if include?(Enumerable)
           blacklist += Enumerable.public_instance_methods
-          blacklist -= [:sort, :count, :first, :min, :max, :include?]
+          blacklist -= %i[sort count first min max include?]
         end
+
         whitelist = [:to_liquid] + (public_instance_methods - blacklist)
-        @invokable_methods = Set.new(whitelist.map(&:to_s))
+        Set.new(whitelist.map(&:to_s))
       end
-      @invokable_methods.include?(method_name.to_s)
     end
   end
 end

lib/liquid/errors.rb

@@ -1,12 +1,58 @@
-module Liquid
-  class Error < ::StandardError; end
+# frozen_string_literal: true
 
-  class ArgumentError < Error; end
-  class ContextError < Error; end
-  class FilterNotFound < Error; end
-  class FileSystemError < Error; end
-  class StandardError < Error; end
-  class SyntaxError < Error; end
-  class StackLevelError < Error; end
-  class MemoryError < Error; end
+module Liquid
+  class Error < ::StandardError
+    attr_accessor :line_number
+    attr_accessor :template_name
+    attr_accessor :markup_context
+
+    def to_s(with_prefix = true)
+      str = +''
+      str << message_prefix if with_prefix
+      str << super()
+
+      if markup_context
+        str << ' '
+        str << markup_context
+      end
+
+      str
+    end
+
+    private
+
+    def message_prefix
+      str = +''
+      str << if is_a?(SyntaxError)
+        'Liquid syntax error'
+      else
+        'Liquid error'
+      end
+
+      if line_number
+        str << ' ('
+        str << template_name << ' ' if template_name
+        str << 'line ' << line_number.to_s << ')'
+      end
+
+      str << ': '
+      str
+    end
+  end
+
+  ArgumentError = Class.new(Error)
+  ContextError = Class.new(Error)
+  FileSystemError = Class.new(Error)
+  StandardError = Class.new(Error)
+  SyntaxError = Class.new(Error)
+  StackLevelError = Class.new(Error)
+  TaintedError = Class.new(Error)
+  MemoryError = Class.new(Error)
+  ZeroDivisionError = Class.new(Error)
+  FloatDomainError = Class.new(Error)
+  UndefinedVariable = Class.new(Error)
+  UndefinedDropMethod = Class.new(Error)
+  UndefinedFilter = Class.new(Error)
+  MethodOverrideError = Class.new(Error)
+  InternalError = Class.new(Error)
 end

lib/liquid/expression.rb

@@ -0,0 +1,51 @@
+# frozen_string_literal: true
+
+module Liquid
+  class Expression
+    class MethodLiteral
+      attr_reader :method_name, :to_s
+
+      def initialize(method_name, to_s)
+        @method_name = method_name
+        @to_s = to_s
+      end
+
+      def to_liquid
+        to_s
+      end
+    end
+
+    LITERALS = {
+      nil => nil, 'nil' => nil, 'null' => nil, '' => nil,
+      'true' => true,
+      'false' => false,
+      'blank' => MethodLiteral.new(:blank?, '').freeze,
+      'empty' => MethodLiteral.new(:empty?, '').freeze
+    }.freeze
+
+    SINGLE_QUOTED_STRING = /\A'(.*)'\z/m.freeze
+    DOUBLE_QUOTED_STRING = /\A"(.*)"\z/m.freeze
+    INTEGERS_REGEX       = /\A(-?\d+)\z/.freeze
+    FLOATS_REGEX         = /\A(-?\d[\d\.]+)\z/.freeze
+    RANGES_REGEX         = /\A\((\S+)\.\.(\S+)\)\z/.freeze
+
+    def self.parse(markup)
+      if LITERALS.key?(markup)
+        LITERALS[markup]
+      else
+        case markup
+        when SINGLE_QUOTED_STRING, DOUBLE_QUOTED_STRING
+          Regexp.last_match(1)
+        when INTEGERS_REGEX
+          Regexp.last_match(1).to_i
+        when RANGES_REGEX
+          RangeLookup.parse(Regexp.last_match(1), Regexp.last_match(2))
+        when FLOATS_REGEX
+          Regexp.last_match(1).to_f
+        else
+          VariableLookup.parse(markup)
+        end
+      end
+    end
+  end
+end

lib/liquid/extensions.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'time'
 require 'date'
 
@@ -7,44 +9,56 @@ class String # :nodoc:
   end
 end
 
-class Array  # :nodoc:
+class Symbol # :nodoc:
+  def to_liquid
+    to_s
+  end
+end
+
+class Array # :nodoc:
   def to_liquid
     self
   end
 end
 
-class Hash  # :nodoc:
+class Hash # :nodoc:
   def to_liquid
     self
   end
 end
 
-class Numeric  # :nodoc:
+class Numeric # :nodoc:
   def to_liquid
     self
   end
 end
 
-class Time  # :nodoc:
+class Range # :nodoc:
   def to_liquid
     self
   end
 end
 
-class DateTime < Date  # :nodoc:
+class Time # :nodoc:
   def to_liquid
     self
   end
 end
 
-class Date  # :nodoc:
+class DateTime < Date # :nodoc:
+  def to_liquid
+    self
+  end
+end
+
+class Date # :nodoc:
   def to_liquid
     self
   end
 end
 
 class TrueClass
-  def to_liquid  # :nodoc:
+  def to_liquid # :nodoc:
     self
   end
 end

lib/liquid/file_system.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # A Liquid file system is a way to let your templates retrieve other templates for use with the include tag.
   #
@@ -8,14 +10,14 @@ module Liquid
   #
   # Example:
   #
-  # Liquid::Template.file_system = Liquid::LocalFileSystem.new(template_path)
-  # liquid = Liquid::Template.parse(template)
+  #   Liquid::Template.file_system = Liquid::LocalFileSystem.new(template_path)
+  #   liquid = Liquid::Template.parse(template)
   #
   # This will parse the template with a LocalFileSystem implementation rooted at 'template_path'.
   class BlankFileSystem
     # Called by Liquid to retrieve a template file
-    def read_template_file(template_path, context)
-      raise FileSystemError, "This liquid context does not allow includes."
+    def read_template_file(_template_path)
+      raise FileSystemError, 'This liquid context does not allow includes.'
     end
   end
 
@@ -26,10 +28,10 @@ module Liquid
   #
   # Example:
   #
-  # file_system = Liquid::LocalFileSystem.new("/some/path")
+  #   file_system = Liquid::LocalFileSystem.new("/some/path")
   #
-  # file_system.full_path("mypartial")       # => "/some/path/_mypartial.liquid"
-  # file_system.full_path("dir/mypartial")   # => "/some/path/dir/_mypartial.liquid"
+  #   file_system.full_path("mypartial")       # => "/some/path/_mypartial.liquid"
+  #   file_system.full_path("dir/mypartial")   # => "/some/path/dir/_mypartial.liquid"
   #
   # Optionally in the second argument you can specify a custom pattern for template filenames.
   # The Kernel::sprintf format specification is used.
@@ -37,35 +39,35 @@ module Liquid
   #
   # Example:
   #
-  # file_system = Liquid::LocalFileSystem.new("/some/path", "%s.html")
+  #   file_system = Liquid::LocalFileSystem.new("/some/path", "%s.html")
   #
-  # file_system.full_path("index") # => "/some/path/index.html"
+  #   file_system.full_path("index") # => "/some/path/index.html"
   #
   class LocalFileSystem
     attr_accessor :root
 
-    def initialize(root, pattern = "_%s.liquid".freeze)
+    def initialize(root, pattern = '_%s.liquid')
       @root = root
       @pattern = pattern
     end
 
-    def read_template_file(template_path, context)
+    def read_template_file(template_path)
       full_path = full_path(template_path)
-      raise FileSystemError, "No such template '#{template_path}'" unless File.exists?(full_path)
+      raise FileSystemError, "No such template '#{template_path}'" unless File.exist?(full_path)
 
       File.read(full_path)
     end
 
     def full_path(template_path)
-      raise FileSystemError, "Illegal template name '#{template_path}'" unless template_path =~ /\A[^.\/][a-zA-Z0-9_\/]+\z/
+      raise FileSystemError, "Illegal template name '#{template_path}'" unless template_path =~ %r{\A[^./][a-zA-Z0-9_/]+\z}
 
-      full_path = if template_path.include?('/'.freeze)
+      full_path = if template_path.include?('/')
         File.join(root, File.dirname(template_path), @pattern % File.basename(template_path))
       else
         File.join(root, @pattern % template_path)
       end
 
-      raise FileSystemError, "Illegal template path '#{File.expand_path(full_path)}'" unless File.expand_path(full_path) =~ /\A#{File.expand_path(root)}/
+      raise FileSystemError, "Illegal template path '#{File.expand_path(full_path)}'" unless File.expand_path(full_path).start_with?(File.expand_path(root))
 
       full_path
     end

lib/liquid/forloop_drop.rb

@@ -0,0 +1,44 @@
+# frozen_string_literal: true
+
+module Liquid
+  class ForloopDrop < Drop
+    def initialize(name, length, parentloop)
+      @name = name
+      @length = length
+      @parentloop = parentloop
+      @index = 0
+    end
+
+    attr_reader :name, :length, :parentloop
+
+    def index
+      @index + 1
+    end
+
+    def index0
+      @index
+    end
+
+    def rindex
+      @length - @index
+    end
+
+    def rindex0
+      @length - @index - 1
+    end
+
+    def first
+      @index == 0
+    end
+
+    def last
+      @index == @length - 1
+    end
+
+    protected
+
+    def increment!
+      @index += 1
+    end
+  end
+end

lib/liquid/i18n.rb

@@ -1,11 +1,12 @@
+# frozen_string_literal: true
+
 require 'yaml'
 
 module Liquid
   class I18n
-    DEFAULT_LOCALE = File.join(File.expand_path(File.dirname(__FILE__)), "locales", "en.yml")
+    DEFAULT_LOCALE = File.join(File.expand_path(__dir__), 'locales', 'en.yml')
 
-    class TranslationError < StandardError
-    end
+    TranslationError = Class.new(StandardError)
 
     attr_reader :path
 
@@ -23,16 +24,17 @@ module Liquid
     end
 
     private
+
     def interpolate(name, vars)
-      name.gsub(/%\{(\w+)\}/) {
+      name.gsub(/%\{(\w+)\}/) do
         # raise TranslationError, "Undefined key #{$1} for interpolation in translation #{name}"  unless vars[$1.to_sym]
-        "#{vars[$1.to_sym]}"
-      }
+        (vars[Regexp.last_match(1).to_sym]).to_s
+      end
     end
 
     def deep_fetch_translation(name)
-      name.split('.'.freeze).reduce(locale) do |level, cur|
-        level[cur] or raise TranslationError, "Translation for #{name} does not exist in locale #{path}"
+      name.split('.').reduce(locale) do |level, cur|
+        level[cur] || raise(TranslationError, "Translation for #{name} does not exist in locale #{path}")
       end
     end
   end

lib/liquid/interrupts.rb

@@ -1,17 +1,18 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # An interrupt is any command that breaks processing of a block (ex: a for loop).
   class Interrupt
     attr_reader :message
 
-    def initialize(message=nil)
-      @message = message || "interrupt".freeze
+    def initialize(message = nil)
+      @message = message || 'interrupt'
     end
   end
 
   # Interrupt that is thrown whenever a {% break %} is called.
-  class BreakInterrupt < Interrupt; end
+  class BreakInterrupt < RuntimeError; end
 
   # Interrupt that is thrown whenever a {% continue %} is called.
-  class ContinueInterrupt < Interrupt; end
+  class ContinueInterrupt < RuntimeError; end
 end

lib/liquid/legacy.rb

@@ -0,0 +1,79 @@
+# frozen_string_literal: true
+
+module Liquid
+  FilterSeparator = FILTER_SEPARATOR
+  ArgumentSeparator = ARGUMENT_SEPARATOR
+  FilterArgumentSeparator = FILTER_ARGUMENT_SEPARATOR
+  VariableAttributeSeparator = VARIABLE_ATTRIBUTE_SEPARATOR
+  WhitespaceControl = WHITESPACE_CONTROL
+  TagStart = TAG_START
+  TagEnd = TAG_END
+  VariableSignature = VARIABLE_SIGNATURE
+  VariableSegment = VARIABLE_SEGMENT
+  VariableStart = VARIABLE_START
+  VariableEnd = VARIABLE_END
+  VariableIncompleteEnd = VARIABLE_INCOMPLETE_END
+  QuotedString = QUOTED_STRING
+  QuotedFragment = QUOTED_FRAGMENT
+  TagAttributes = TAG_ATTRIBUTES
+  AnyStartingTag = ANY_STARTING_TAG
+  PartialTemplateParser = PARTIAL_TEMPLATE_PARSER
+  TemplateParser = TEMPLATE_PARSER
+  VariableParser = VARIABLE_PARSER
+
+  class BlockBody
+    FullToken = FULL_TOKEN
+    ContentOfVariable = CONTENT_OF_VARIABLE
+    WhitespaceOrNothing = WHITESPACE_OR_NOTHING
+    TAGSTART = TAG_START
+    VARSTART = VAR_START
+  end
+
+  class Assign < Tag
+    Syntax = SYNTAX
+  end
+
+  class Capture < Block
+    Syntax = SYNTAX
+  end
+
+  class Case < Block
+    Syntax     = SYNTAX
+    WhenSyntax = WHEN_SYNTAX
+  end
+
+  class Cycle < Tag
+    SimpleSyntax = SIMPLE_SYNTAX
+    NamedSyntax  = NAMED_SYNTAX
+  end
+
+  class For < Block
+    Syntax = SYNTAX
+  end
+
+  class If < Block
+    Syntax = SYNTAX
+    ExpressionsAndOperators = EXPRESSIONS_AND_OPERATORS
+  end
+
+  class Include < Tag
+    Syntax = SYNTAX
+  end
+
+  class Raw < Block
+    Syntax = SYNTAX
+    FullTokenPossiblyInvalid = FULL_TOKEN_POSSIBLY_INVALID
+  end
+
+  class TableRow < Block
+    Syntax = SYNTAX
+  end
+
+  class Variable
+    FilterMarkupRegex = FILTER_MARKUP_REGEX
+    FilterParser = FILTER_PARSER
+    FilterArgsRegex = FILTER_ARGS_REGEX
+    JustTagAttributes = JUST_TAG_ATTRIBUTES
+    MarkupWithQuotedFragment = MARKUP_WITH_QUOTED_FRAGMENT
+  end
+end

lib/liquid/lexer.rb

@@ -1,43 +1,49 @@
-require "strscan"
+# frozen_string_literal: true
+
+require 'strscan'
 module Liquid
   class Lexer
     SPECIALS = {
-      '|'.freeze => :pipe,
-      '.'.freeze => :dot,
-      ':'.freeze => :colon,
-      ','.freeze => :comma,
-      '['.freeze => :open_square,
-      ']'.freeze => :close_square,
-      '('.freeze => :open_round,
-      ')'.freeze => :close_round
-    }
-    IDENTIFIER = /[\w\-?!]+/
-    SINGLE_STRING_LITERAL = /'[^\']*'/
-    DOUBLE_STRING_LITERAL = /"[^\"]*"/
-    NUMBER_LITERAL = /-?\d+(\.\d+)?/
-    DOTDOT = /\.\./
-    COMPARISON_OPERATOR = /==|!=|<>|<=?|>=?|contains/
+      '|' => :pipe,
+      '.' => :dot,
+      ':' => :colon,
+      ',' => :comma,
+      '[' => :open_square,
+      ']' => :close_square,
+      '(' => :open_round,
+      ')' => :close_round,
+      '?' => :question,
+      '-' => :dash,
+    }.freeze
+    IDENTIFIER = /[a-zA-Z_][\w-]*\??/.freeze
+    SINGLE_STRING_LITERAL = /'[^\']*'/.freeze
+    DOUBLE_STRING_LITERAL = /"[^\"]*"/.freeze
+    NUMBER_LITERAL = /-?\d+(\.\d+)?/.freeze
+    DOTDOT = /\.\./.freeze
+    COMPARISON_OPERATOR = /==|!=|<>|<=?|>=?|contains(?=\s)/.freeze
+    WHITESPACE_OR_NOTHING = /\s*/.freeze
 
     def initialize(input)
-      @ss = StringScanner.new(input.rstrip)
+      @ss = StringScanner.new(input)
     end
 
     def tokenize
       @output = []
 
-      while !@ss.eos?
-        @ss.skip(/\s*/)
-        tok = case
-        when t = @ss.scan(COMPARISON_OPERATOR) then [:comparison, t]
-        when t = @ss.scan(SINGLE_STRING_LITERAL) then [:string, t]
-        when t = @ss.scan(DOUBLE_STRING_LITERAL) then [:string, t]
-        when t = @ss.scan(NUMBER_LITERAL) then [:number, t]
-        when t = @ss.scan(IDENTIFIER) then [:id, t]
-        when t = @ss.scan(DOTDOT) then [:dotdot, t]
+      until @ss.eos?
+        @ss.skip(WHITESPACE_OR_NOTHING)
+        break if @ss.eos?
+
+        tok = if (t = @ss.scan(COMPARISON_OPERATOR)) then [:comparison, t]
+        elsif (t = @ss.scan(SINGLE_STRING_LITERAL)) then [:string, t]
+        elsif (t = @ss.scan(DOUBLE_STRING_LITERAL)) then [:string, t]
+        elsif (t = @ss.scan(NUMBER_LITERAL)) then [:number, t]
+        elsif (t = @ss.scan(IDENTIFIER)) then [:id, t]
+        elsif (t = @ss.scan(DOTDOT)) then [:dotdot, t]
         else
           c = @ss.getch
-          if s = SPECIALS[c]
-            [s,c]
+          if (s = SPECIALS[c])
+            [s, c]
           else
             raise SyntaxError, "Unexpected character #{c}"
           end

lib/liquid/locales/en.yml

@@ -1,6 +1,7 @@
 ---
   errors:
     syntax:
+      tag_unexpected_args: "Syntax Error in '%{tag}' - Valid syntax: %{tag}"
       assign: "Syntax Error in 'assign' - Valid syntax: assign [var] = [source]"
       capture: "Syntax Error in 'capture' - Valid syntax: capture [var]"
       case: "Syntax Error in 'case' - Valid syntax: case [condition]"
@@ -13,10 +14,13 @@
       if: "Syntax Error in tag 'if' - Valid syntax: if [expression]"
       include: "Error in tag 'include' - Valid syntax: include '[template]' (with|for) [object|collection]"
       unknown_tag: "Unknown tag '%{tag}'"
-      invalid_delimiter: "'end' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
-      unexpected_else: "%{block_name} tag does not expect else tag"
+      invalid_delimiter: "'%{tag}' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
+      unexpected_else: "%{block_name} tag does not expect 'else' tag"
+      unexpected_outer_tag: "Unexpected outer '%{tag}' tag"
       tag_termination: "Tag '%{token}' was not properly terminated with regexp: %{tag_end}"
       variable_termination: "Variable '%{token}' was not properly terminated with regexp: %{tag_end}"
       tag_never_closed: "'%{block_name}' tag was never closed"
       meta_syntax_error: "Liquid syntax error: #{e.message}"
       table_row: "Syntax Error in 'table_row loop' - Valid syntax: table_row [item] in [collection] cols=3"
+    argument:
+      include: "Argument error in tag 'include' - Illegal template name"

lib/liquid/module_ex.rb

@@ -1,62 +0,0 @@
-# Copyright 2007 by Domizio Demichelis
-# This library is free software. It may be used, redistributed and/or modified
-# under the same terms as Ruby itself
-#
-# This extension is used in order to expose the object of the implementing class
-# to liquid as it were a Drop. It also limits the liquid-callable methods of the instance
-# to the allowed method passed with the liquid_methods call
-# Example:
-#
-# class SomeClass
-#   liquid_methods :an_allowed_method
-#
-#   def an_allowed_method
-#     'this comes from an allowed method'
-#   end
-#   def unallowed_method
-#     'this will never be an output'
-#   end
-# end
-#
-# if you want to extend the drop to other methods you can defines more methods
-# in the class <YourClass>::LiquidDropClass
-#
-#   class SomeClass::LiquidDropClass
-#     def another_allowed_method
-#       'and this from another allowed method'
-#     end
-#   end
-# end
-#
-# usage:
-# @something = SomeClass.new
-#
-# template:
-# {{something.an_allowed_method}}{{something.unallowed_method}} {{something.another_allowed_method}}
-#
-# output:
-# 'this comes from an allowed method and this from another allowed method'
-#
-# You can also chain associations, by adding the liquid_method call in the
-# association models.
-#
-class Module
-
-  def liquid_methods(*allowed_methods)
-    drop_class = eval "class #{self.to_s}::LiquidDropClass < Liquid::Drop; self; end"
-    define_method :to_liquid do
-      drop_class.new(self)
-    end
-    drop_class.class_eval do
-      def initialize(object)
-        @object = object
-      end
-      allowed_methods.each do |sym|
-        define_method sym do
-          @object.send sym
-        end
-      end
-    end
-  end
-
-end

lib/liquid/parse_context.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module Liquid
+  class ParseContext
+    attr_accessor :locale, :line_number, :trim_whitespace, :depth
+    attr_reader :partial, :warnings, :error_mode
+
+    def initialize(options = {})
+      @template_options = options ? options.dup : {}
+      @locale = @template_options[:locale] ||= I18n.new
+      @warnings = []
+      self.depth = 0
+      self.partial = false
+    end
+
+    def [](option_key)
+      @options[option_key]
+    end
+
+    def partial=(value)
+      @partial = value
+      @options = value ? partial_options : @template_options
+      @error_mode = @options[:error_mode] || Template.error_mode
+    end
+
+    def partial_options
+      @partial_options ||= begin
+        dont_pass = @template_options[:include_options_blacklist]
+        if dont_pass == true
+          { locale: locale }
+        elsif dont_pass.is_a?(Array)
+          @template_options.reject { |k, _v| dont_pass.include?(k) }
+        else
+          @template_options
+        end
+      end
+    end
+  end
+end

lib/liquid/parse_tree_visitor.rb

@@ -0,0 +1,42 @@
+# frozen_string_literal: true
+
+module Liquid
+  class ParseTreeVisitor
+    def self.for(node, callbacks = Hash.new(proc {}))
+      if defined?(node.class::ParseTreeVisitor)
+        node.class::ParseTreeVisitor
+      else
+        self
+      end.new(node, callbacks)
+    end
+
+    def initialize(node, callbacks)
+      @node = node
+      @callbacks = callbacks
+    end
+
+    def add_callback_for(*classes, &block)
+      callback = block
+      callback = ->(node, _) { yield node } if block.arity.abs == 1
+      callback = ->(_, _) { yield } if block.arity.zero?
+      classes.each { |klass| @callbacks[klass] = callback }
+      self
+    end
+
+    def visit(context = nil)
+      children.map do |node|
+        item, new_context = @callbacks[node.class].call(node, context)
+        [
+          item,
+          ParseTreeVisitor.for(node, @callbacks).visit(new_context || context),
+        ]
+      end
+    end
+
+    protected
+
+    def children
+      @node.respond_to?(:nodelist) ? Array(@node.nodelist) : []
+    end
+  end
+end

lib/liquid/parser.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Parser
     def initialize(input)
@@ -12,9 +14,8 @@ module Liquid
 
     def consume(type = nil)
       token = @tokens[@p]
-      if type && token[0] != type
-        raise SyntaxError, "Expected #{type} but found #{@tokens[@p].first}"
-      end
+      raise SyntaxError, "Expected #{type} but found #{@tokens[@p].first}" if type && token[0] != type
+
       @p += 1
       token[1]
     end
@@ -25,6 +26,7 @@ module Liquid
     def consume?(type)
       token = @tokens[@p]
       return false unless token && token[0] == type
+
       @p += 1
       token[1]
     end
@@ -34,6 +36,7 @@ module Liquid
       token = @tokens[@p]
       return false unless token && token[0] == :id
       return false unless token[1] == str
+
       @p += 1
       token[1]
     end
@@ -41,14 +44,18 @@ module Liquid
     def look(type, ahead = 0)
       tok = @tokens[@p + ahead]
       return false unless tok
+
       tok[0] == type
     end
 
+    SINGLE_TOKEN_EXPRESSION_TYPES = %i[string number].freeze
+    private_constant :SINGLE_TOKEN_EXPRESSION_TYPES
+
     def expression
       token = @tokens[@p]
       if token[0] == :id
         variable_signature
-      elsif [:string, :number].include? token[0]
+      elsif SINGLE_TOKEN_EXPRESSION_TYPES.include?(token[0])
         consume
       elsif token.first == :open_round
         consume
@@ -63,11 +70,9 @@ module Liquid
     end
 
     def argument
-      str = ""
+      str = +''
       # might be a keyword argument (identifier: expression)
-      if look(:id) && look(:colon, 1)
-        str << consume << consume << ' '.freeze
-      end
+      str << consume << consume << ' ' if look(:id) && look(:colon, 1)
 
       str << expression
       str
@@ -75,7 +80,7 @@ module Liquid
 
     def variable_signature
       str = consume(:id)
-      if look(:open_square)
+      while look(:open_square)
         str << consume
         str << expression
         str << consume(:close_square)

lib/liquid/parser_switching.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Liquid
+  module ParserSwitching
+    def parse_with_selected_parser(markup)
+      case parse_context.error_mode
+      when :strict then strict_parse_with_error_context(markup)
+      when :lax    then lax_parse(markup)
+      when :warn
+        begin
+          return strict_parse_with_error_context(markup)
+        rescue SyntaxError => e
+          parse_context.warnings << e
+          return lax_parse(markup)
+        end
+      end
+    end
+
+    private
+
+    def strict_parse_with_error_context(markup)
+      strict_parse(markup)
+    rescue SyntaxError => e
+      e.line_number = line_number
+      e.markup_context = markup_context(markup)
+      raise e
+    end
+
+    def markup_context(markup)
+      "in \"#{markup.strip}\""
+    end
+  end
+end

lib/liquid/profiler.rb

@@ -0,0 +1,160 @@
+# frozen_string_literal: true
+
+require 'liquid/profiler/hooks'
+
+module Liquid
+  # Profiler enables support for profiling template rendering to help track down performance issues.
+  #
+  # To enable profiling, first require 'liquid/profiler'.
+  # Then, to profile a parse/render cycle, pass the <tt>profile: true</tt> option to <tt>Liquid::Template.parse</tt>.
+  # After <tt>Liquid::Template#render</tt> is called, the template object makes available an instance of this
+  # class via the <tt>Liquid::Template#profiler</tt> method.
+  #
+  #   template = Liquid::Template.parse(template_content, profile: true)
+  #   output  = template.render
+  #   profile = template.profiler
+  #
+  # This object contains all profiling information, containing information on what tags were rendered,
+  # where in the templates these tags live, and how long each tag took to render.
+  #
+  # This is a tree structure that is Enumerable all the way down, and keeps track of tags and rendering times
+  # inside of <tt>{% include %}</tt> tags.
+  #
+  #   profile.each do |node|
+  #     # Access to the node itself
+  #     node.code
+  #
+  #     # Which template and line number of this node.
+  #     # If top level, this will be "<root>".
+  #     node.partial
+  #     node.line_number
+  #
+  #     # Render time in seconds of this node
+  #     node.render_time
+  #
+  #     # If the template used {% include %}, this node will also have children.
+  #     node.children.each do |child2|
+  #       # ...
+  #     end
+  #   end
+  #
+  # Profiler also exposes the total time of the template's render in <tt>Liquid::Profiler#total_render_time</tt>.
+  #
+  # All render times are in seconds. There is a small performance hit when profiling is enabled.
+  #
+  class Profiler
+    include Enumerable
+
+    class Timing
+      attr_reader :code, :partial, :line_number, :children
+
+      def initialize(node, partial)
+        @code        = node.respond_to?(:raw) ? node.raw : node
+        @partial     = partial
+        @line_number = node.respond_to?(:line_number) ? node.line_number : nil
+        @children    = []
+      end
+
+      def self.start(node, partial)
+        new(node, partial).tap(&:start)
+      end
+
+      def start
+        @start_time = Time.now
+      end
+
+      def finish
+        @end_time = Time.now
+      end
+
+      def render_time
+        @end_time - @start_time
+      end
+    end
+
+    def self.profile_node_render(node)
+      if Profiler.current_profile && node.respond_to?(:render)
+        Profiler.current_profile.start_node(node)
+        output = yield
+        Profiler.current_profile.end_node(node)
+        output
+      else
+        yield
+      end
+    end
+
+    def self.profile_children(template_name)
+      if Profiler.current_profile
+        Profiler.current_profile.push_partial(template_name)
+        output = yield
+        Profiler.current_profile.pop_partial
+        output
+      else
+        yield
+      end
+    end
+
+    def self.current_profile
+      Thread.current[:liquid_profiler]
+    end
+
+    def initialize
+      @partial_stack = ['<root>']
+
+      @root_timing = Timing.new('', current_partial)
+      @timing_stack = [@root_timing]
+
+      @render_start_at = Time.now
+      @render_end_at = @render_start_at
+    end
+
+    def start
+      Thread.current[:liquid_profiler] = self
+      @render_start_at = Time.now
+    end
+
+    def stop
+      Thread.current[:liquid_profiler] = nil
+      @render_end_at = Time.now
+    end
+
+    def total_render_time
+      @render_end_at - @render_start_at
+    end
+
+    def each(&block)
+      @root_timing.children.each(&block)
+    end
+
+    def [](idx)
+      @root_timing.children[idx]
+    end
+
+    def length
+      @root_timing.children.length
+    end
+
+    def start_node(node)
+      @timing_stack.push(Timing.start(node, current_partial))
+    end
+
+    def end_node(_node)
+      timing = @timing_stack.pop
+      timing.finish
+
+      @timing_stack.last.children << timing
+    end
+
+    def current_partial
+      @partial_stack.last
+    end
+
+    def push_partial(partial_name)
+      @partial_stack.push(partial_name)
+    end
+
+    def pop_partial
+      @partial_stack.pop
+    end
+  end
+end

lib/liquid/profiler/hooks.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Liquid
+  class BlockBody
+    def render_node_with_profiling(context, output, node)
+      Profiler.profile_node_render(node) do
+        render_node_without_profiling(context, output, node)
+      end
+    end
+
+    alias_method :render_node_without_profiling, :render_node
+    alias_method :render_node, :render_node_with_profiling
+  end
+
+  class Include < Tag
+    def render_to_output_buffer_with_profiling(context, output)
+      Profiler.profile_children(context.evaluate(@template_name_expr).to_s) do
+        render_to_output_buffer_without_profiling(context, output)
+      end
+    end
+
+    alias_method :render_to_output_buffer_without_profiling, :render_to_output_buffer
+    alias_method :render_to_output_buffer, :render_to_output_buffer_with_profiling
+  end
+end

lib/liquid/range_lookup.rb

@@ -0,0 +1,39 @@
+# frozen_string_literal: true
+
+module Liquid
+  class RangeLookup
+    def self.parse(start_markup, end_markup)
+      start_obj = Expression.parse(start_markup)
+      end_obj = Expression.parse(end_markup)
+      if start_obj.respond_to?(:evaluate) || end_obj.respond_to?(:evaluate)
+        new(start_obj, end_obj)
+      else
+        start_obj.to_i..end_obj.to_i
+      end
+    end
+
+    def initialize(start_obj, end_obj)
+      @start_obj = start_obj
+      @end_obj = end_obj
+    end
+
+    def evaluate(context)
+      start_int = to_integer(context.evaluate(@start_obj))
+      end_int = to_integer(context.evaluate(@end_obj))
+      start_int..end_int
+    end
+
+    private
+
+    def to_integer(input)
+      case input
+      when Integer
+        input
+      when NilClass, String
+        input.to_i
+      else
+        Utils.to_integer(input)
+      end
+    end
+  end
+end

lib/liquid/resource_limits.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+module Liquid
+  class ResourceLimits
+    attr_accessor :render_length, :render_score, :assign_score,
+                  :render_length_limit, :render_score_limit, :assign_score_limit
+
+    def initialize(limits)
+      @render_length_limit = limits[:render_length_limit]
+      @render_score_limit = limits[:render_score_limit]
+      @assign_score_limit = limits[:assign_score_limit]
+      reset
+    end
+
+    def reached?
+      (@render_length_limit && @render_length > @render_length_limit) ||
+        (@render_score_limit && @render_score > @render_score_limit) ||
+        (@assign_score_limit && @assign_score > @assign_score_limit)
+    end
+
+    def reset
+      @render_length = @render_score = @assign_score = 0
+    end
+  end
+end

lib/liquid/standardfilters.rb

@@ -1,17 +1,24 @@
+# frozen_string_literal: true
+
 require 'cgi'
 require 'bigdecimal'
 
 module Liquid
-
   module StandardFilters
     HTML_ESCAPE = {
-      '&'.freeze => '&'.freeze,
-      '>'.freeze => '>'.freeze,
-      '<'.freeze => '&lt;'.freeze,
-      '"'.freeze => '&quot;'.freeze,
-      "'".freeze => '&#39;'.freeze
-    }
-    HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+));)/
+      '&' => '&amp;',
+      '>' => '&gt;',
+      '<' => '&lt;',
+      '"' => '&quot;',
+      "'" => '&#39;',
+    }.freeze
+    HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+));)/.freeze
+    STRIP_HTML_BLOCKS = Regexp.union(
+      %r{<script.*?</script>}m,
+      /<!--.*?-->/m,
+      %r{<style.*?</style>}m
+    )
+    STRIP_HTML_TAGS = /<.*?>/m.freeze
 
     # Return the size of an array or of an string
     def size(input)
@@ -34,29 +41,58 @@ module Liquid
     end
 
     def escape(input)
-      CGI.escapeHTML(input) rescue input
+      CGI.escapeHTML(input.to_s).untaint unless input.nil?
     end
+    alias_method :h, :escape
 
     def escape_once(input)
       input.to_s.gsub(HTML_ESCAPE_ONCE_REGEXP, HTML_ESCAPE)
     end
 
-    alias_method :h, :escape
-
-    # Truncate a string down to x characters
-    def truncate(input, length = 50, truncate_string = "...".freeze)
-      if input.nil? then return end
-      l = length.to_i - truncate_string.length
-      l = 0 if l < 0
-      input.length > length.to_i ? input[0...l] + truncate_string : input
+    def url_encode(input)
+      CGI.escape(input.to_s) unless input.nil?
     end
 
-    def truncatewords(input, words = 15, truncate_string = "...".freeze)
-      if input.nil? then return end
-      wordlist = input.to_s.split
-      l = words.to_i - 1
+    def url_decode(input)
+      return if input.nil?
+
+      result = CGI.unescape(input.to_s)
+      raise Liquid::ArgumentError, "invalid byte sequence in #{result.encoding}" unless result.valid_encoding?
+
+      result
+    end
+
+    def slice(input, offset, length = nil)
+      offset = Utils.to_integer(offset)
+      length = length ? Utils.to_integer(length) : 1
+
+      if input.is_a?(Array)
+        input.slice(offset, length) || []
+      else
+        input.to_s.slice(offset, length) || ''
+      end
+    end
+
+    # Truncate a string down to x characters
+    def truncate(input, length = 50, truncate_string = '...')
+      return if input.nil?
+
+      input_str = input.to_s
+      length = Utils.to_integer(length)
+      truncate_string_str = truncate_string.to_s
+      l = length - truncate_string_str.length
       l = 0 if l < 0
-      wordlist.length > l ? wordlist[0..l].join(" ".freeze) + truncate_string : input
+      input_str.length > length ? input_str[0...l].concat(truncate_string_str) : input_str
+    end
+
+    def truncatewords(input, words = 15, truncate_string = '...')
+      return if input.nil?
+
+      wordlist = input.to_s.split
+      words = Utils.to_integer(words)
+      l = words - 1
+      l = 0 if l < 0
+      wordlist.length > l ? wordlist[0..l].join(' ').concat(truncate_string.to_s) : input
     end
 
     # Split input string into an array of substrings separated by given pattern.
@@ -65,7 +101,7 @@ module Liquid
     #   <div class="summary">{{ post | split '//' | first }}</div>
     #
     def split(input, pattern)
-      input.split(pattern)
+      input.to_s.split(pattern.to_s)
     end
 
     def strip(input)
@@ -81,17 +117,19 @@ module Liquid
     end
 
     def strip_html(input)
-      empty = ''.freeze
-      input.to_s.gsub(/<script.*?<\/script>/m, empty).gsub(/<!--.*?-->/m, empty).gsub(/<style.*?<\/style>/m, empty).gsub(/<.*?>/m, empty)
+      empty = ''
+      result = input.to_s.gsub(STRIP_HTML_BLOCKS, empty)
+      result.gsub!(STRIP_HTML_TAGS, empty)
+      result
     end
 
     # Remove all newlines from the string
     def strip_newlines(input)
-      input.to_s.gsub(/\r?\n/, ''.freeze)
+      input.to_s.gsub(/\r?\n/, '')
     end
 
     # Join elements of the array with certain character between them
-    def join(input, glue = ' '.freeze)
+    def join(input, glue = ' ')
       InputIterator.new(input).join(glue)
     end
 
@@ -99,12 +137,79 @@ module Liquid
     # provide optional property with which to sort an array of hashes or drops
     def sort(input, property = nil)
       ary = InputIterator.new(input)
+
+      return [] if ary.empty?
+
       if property.nil?
-        ary.sort
-      elsif ary.first.respond_to?('[]'.freeze) && !ary.first[property].nil?
-        ary.sort {|a,b| a[property] <=> b[property] }
-      elsif ary.first.respond_to?(property)
-        ary.sort {|a,b| a.send(property) <=> b.send(property) }
+        ary.sort do |a, b|
+          nil_safe_compare(a, b)
+        end
+      elsif ary.all? { |el| el.respond_to?(:[]) }
+        begin
+          ary.sort { |a, b| nil_safe_compare(a[property], b[property]) }
+        rescue TypeError
+          raise_property_error(property)
+        end
+      end
+    end
+
+    # Sort elements of an array ignoring case if strings
+    # provide optional property with which to sort an array of hashes or drops
+    def sort_natural(input, property = nil)
+      ary = InputIterator.new(input)
+
+      return [] if ary.empty?
+
+      if property.nil?
+        ary.sort do |a, b|
+          nil_safe_casecmp(a, b)
+        end
+      elsif ary.all? { |el| el.respond_to?(:[]) }
+        begin
+          ary.sort { |a, b| nil_safe_casecmp(a[property], b[property]) }
+        rescue TypeError
+          raise_property_error(property)
+        end
+      end
+    end
+
+    # Filter the elements of an array to those with a certain property value.
+    # By default the target is any truthy value.
+    def where(input, property, target_value = nil)
+      ary = InputIterator.new(input)
+
+      if ary.empty?
+        []
+      elsif ary.first.respond_to?(:[]) && target_value.nil?
+        begin
+          ary.select { |item| item[property] }
+        rescue TypeError
+          raise_property_error(property)
+        end
+      elsif ary.first.respond_to?(:[])
+        begin
+          ary.select { |item| item[property] == target_value }
+        rescue TypeError
+          raise_property_error(property)
+        end
+      end
+    end
+
+    # Remove duplicate elements from an array
+    # provide optional property with which to determine uniqueness
+    def uniq(input, property = nil)
+      ary = InputIterator.new(input)
+
+      if property.nil?
+        ary.uniq
+      elsif ary.empty? # The next two cases assume a non-empty array.
+        []
+      elsif ary.first.respond_to?(:[])
+        begin
+          ary.uniq { |a| a[property] }
+        rescue TypeError
+          raise_property_error(property)
+        end
       end
     end
 
@@ -119,32 +224,53 @@ module Liquid
       InputIterator.new(input).map do |e|
         e = e.call if e.is_a?(Proc)
 
-        if property == "to_liquid".freeze
+        if property == 'to_liquid'
           e
         elsif e.respond_to?(:[])
-          e[property]
+          r = e[property]
+          r.is_a?(Proc) ? r.call : r
+        end
+      end
+    rescue TypeError
+      raise_property_error(property)
+    end
+
+    # Remove nils within an array
+    # provide optional property with which to check for nil
+    def compact(input, property = nil)
+      ary = InputIterator.new(input)
+
+      if property.nil?
+        ary.compact
+      elsif ary.empty? # The next two cases assume a non-empty array.
+        []
+      elsif ary.first.respond_to?(:[])
+        begin
+          ary.reject { |a| a[property].nil? }
+        rescue TypeError
+          raise_property_error(property)
         end
       end
     end
 
     # Replace occurrences of a string with another
-    def replace(input, string, replacement = ''.freeze)
-      input.to_s.gsub(string, replacement.to_s)
+    def replace(input, string, replacement = '')
+      input.to_s.gsub(string.to_s, replacement.to_s)
     end
 
     # Replace the first occurrences of a string with another
-    def replace_first(input, string, replacement = ''.freeze)
-      input.to_s.sub(string, replacement.to_s)
+    def replace_first(input, string, replacement = '')
+      input.to_s.sub(string.to_s, replacement.to_s)
     end
 
     # remove a substring
     def remove(input, string)
-      input.to_s.gsub(string, ''.freeze)
+      input.to_s.gsub(string.to_s, '')
     end
 
     # remove the first occurrences of a substring
     def remove_first(input, string)
-      input.to_s.sub(string, ''.freeze)
+      input.to_s.sub(string.to_s, '')
     end
 
     # add one string to another
@@ -152,6 +278,12 @@ module Liquid
       input.to_s + string.to_s
     end
 
+    def concat(input, array)
+      raise ArgumentError, 'concat filter requires an array argument' unless array.respond_to?(:to_ary)
+
+      InputIterator.new(input).concat(array)
+    end
+
     # prepend a string to another
     def prepend(input, string)
       string.to_s + input.to_s
@@ -159,7 +291,7 @@ module Liquid
 
     # Add <br /> tags in front of all newlines in input string
     def newline_to_br(input)
-      input.to_s.gsub(/\n/, "<br />\n".freeze)
+      input.to_s.gsub(/\n/, "<br />\n")
     end
 
     # Reformat a date using Ruby's core Time#strftime( string ) -> string
@@ -196,7 +328,7 @@ module Liquid
     def date(input, format)
       return input if format.to_s.empty?
 
-      return input unless date = to_date(input)
+      return input unless (date = Utils.to_date(input))
 
       date.strftime(format.to_s)
     end
@@ -219,6 +351,12 @@ module Liquid
       array.last if array.respond_to?(:last)
     end
 
+    # absolute value
+    def abs(input)
+      result = Utils.to_number(input).abs
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
     # addition
     def plus(input, operand)
       apply_operation(input, operand, :+)
@@ -237,69 +375,88 @@ module Liquid
     # division
     def divided_by(input, operand)
       apply_operation(input, operand, :/)
+    rescue ::ZeroDivisionError => e
+      raise Liquid::ZeroDivisionError, e.message
     end
 
     def modulo(input, operand)
       apply_operation(input, operand, :%)
+    rescue ::ZeroDivisionError => e
+      raise Liquid::ZeroDivisionError, e.message
     end
 
     def round(input, n = 0)
-      result = to_number(input).round(to_number(n))
+      result = Utils.to_number(input).round(Utils.to_number(n))
       result = result.to_f if result.is_a?(BigDecimal)
       result = result.to_i if n == 0
       result
+    rescue ::FloatDomainError => e
+      raise Liquid::FloatDomainError, e.message
     end
 
     def ceil(input)
-      to_number(input).ceil.to_i
+      Utils.to_number(input).ceil.to_i
+    rescue ::FloatDomainError => e
+      raise Liquid::FloatDomainError, e.message
     end
 
     def floor(input)
-      to_number(input).floor.to_i
+      Utils.to_number(input).floor.to_i
+    rescue ::FloatDomainError => e
+      raise Liquid::FloatDomainError, e.message
     end
 
-    def default(input, default_value = "".freeze)
-      is_blank = input.respond_to?(:empty?) ? input.empty? : !input
-      is_blank ? default_value : input
+    def at_least(input, n)
+      min_value = Utils.to_number(n)
+
+      result = Utils.to_number(input)
+      result = min_value if min_value > result
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
+    def at_most(input, n)
+      max_value = Utils.to_number(n)
+
+      result = Utils.to_number(input)
+      result = max_value if max_value < result
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
+    def default(input, default_value = '')
+      if !input || input.respond_to?(:empty?) && input.empty?
+        default_value
+      else
+        input
+      end
     end
 
     private
 
-    def to_number(obj)
-      case obj
-      when Float
-        BigDecimal.new(obj.to_s)
-      when Numeric
-        obj
-      when String
-        (obj.strip =~ /\A\d+\.\d+\z/) ? BigDecimal.new(obj) : obj.to_i
-      else
-        0
-      end
-    end
-
-    def to_date(obj)
-      return obj if obj.respond_to?(:strftime)
-
-      case obj
-      when 'now'.freeze, 'today'.freeze
-        Time.now
-      when /\A\d+\z/, Integer
-        Time.at(obj.to_i)
-      when String
-        Time.parse(obj)
-      else
-        nil
-      end
-    rescue ArgumentError
-      nil
+    def raise_property_error(property)
+      raise Liquid::ArgumentError, "cannot select the property '#{property}'"
     end
 
     def apply_operation(input, operand, operation)
-      result = to_number(input).send(operation, to_number(operand))
+      result = Utils.to_number(input).send(operation, Utils.to_number(operand))
       result.is_a?(BigDecimal) ? result.to_f : result
     end
 
+    def nil_safe_compare(a, b)
+      if !a.nil? && !b.nil?
+        a <=> b
+      else
+        a.nil? ? 1 : -1
+      end
+    end
+
+    def nil_safe_casecmp(a, b)
+      if !a.nil? && !b.nil?
+        a.to_s.casecmp(b.to_s)
+      else
+        a.nil? ? 1 : -1
+      end
+    end
+
     class InputIterator
       include Enumerable
 
@@ -316,13 +473,30 @@ module Liquid
       end
 
       def join(glue)
-        to_a.join(glue)
+        to_a.join(glue.to_s)
+      end
+
+      def concat(args)
+        to_a.concat(args)
       end
 
       def reverse
         reverse_each.to_a
       end
 
+      def uniq(&block)
+        to_a.uniq(&block)
+      end
+
+      def compact
+        to_a.compact
+      end
+
+      def empty?
+        @input.each { return false }
+        true
+      end
+
       def each
         @input.each do |e|
           yield(e.respond_to?(:to_liquid) ? e.to_liquid : e)

lib/liquid/strainer.rb

@@ -1,19 +1,21 @@
+# frozen_string_literal: true
+
 require 'set'
 
 module Liquid
-
   # Strainer is the parent class for the filters system.
   # New filters are mixed into the strainer class which is then instantiated for each liquid template render run.
   #
   # The Strainer only allows method calls defined in filters given to it via Strainer.global_filter,
   # Context#add_filters or Template.register_filter
   class Strainer #:nodoc:
-    @@filters = []
-    @@known_filters = Set.new
-    @@known_methods = Set.new
-    @@strainer_class_cache = Hash.new do |hash, filters|
-      hash[filters] = Class.new(Strainer) do
-        filters.each { |f| include f }
+    @global_strainer = Class.new(Strainer) do
+      @filter_methods = Set.new
+    end
+    @strainer_class_cache = Hash.new do |hash, filters|
+      hash[filters] = Class.new(@global_strainer) do
+        @filter_methods = Strainer.global_strainer.filter_methods.dup
+        filters.each { |f| add_filter(f) }
       end
     end
 
@@ -21,43 +23,48 @@ module Liquid
       @context = context
     end
 
-    def self.global_filter(filter)
-      raise ArgumentError, "Passed filter is not a module" unless filter.is_a?(Module)
-      add_known_filter(filter)
-      @@filters << filter unless @@filters.include?(filter)
+    class << self
+      attr_accessor :strainer_class_cache, :global_strainer
+      attr_reader :filter_methods
     end
 
-    def self.add_known_filter(filter)
-      unless @@known_filters.include?(filter)
-        @@method_blacklist ||= Set.new(Strainer.instance_methods.map(&:to_s))
-        new_methods = filter.instance_methods.map(&:to_s)
-        new_methods.reject!{ |m| @@method_blacklist.include?(m) }
-        @@known_methods.merge(new_methods)
-        @@known_filters.add(filter)
+    def self.add_filter(filter)
+      raise ArgumentError, "Expected module but got: #{filter.class}" unless filter.is_a?(Module)
+
+      unless include?(filter)
+        invokable_non_public_methods = (filter.private_instance_methods + filter.protected_instance_methods).select { |m| invokable?(m) }
+        if invokable_non_public_methods.any?
+          raise MethodOverrideError, "Filter overrides registered public methods as non public: #{invokable_non_public_methods.join(', ')}"
+        else
+          send(:include, filter)
+          @filter_methods.merge(filter.public_instance_methods.map(&:to_s))
+        end
       end
     end
 
-    def self.strainer_class_cache
-      @@strainer_class_cache
+    def self.global_filter(filter)
+      @strainer_class_cache.clear
+      @global_strainer.add_filter(filter)
+    end
+
+    def self.invokable?(method)
+      @filter_methods.include?(method.to_s)
     end
 
     def self.create(context, filters = [])
-      filters = @@filters + filters
-      strainer_class_cache[filters].new(context)
+      @strainer_class_cache[filters].new(context)
     end
 
     def invoke(method, *args)
-      if invokable?(method)
+      if self.class.invokable?(method)
         send(method, *args)
+      elsif @context&.strict_filters
+        raise Liquid::UndefinedFilter, "undefined filter #{method}"
       else
         args.first
       end
     rescue ::ArgumentError => e
-      raise Liquid::ArgumentError.new(e.message)
-    end
-
-    def invokable?(method)
-      @@known_methods.include?(method.to_s) && respond_to?(method)
+      raise Liquid::ArgumentError, e.message, e.backtrace
     end
   end
 end

lib/liquid/tablerowloop_drop.rb

@@ -0,0 +1,64 @@
+# frozen_string_literal: true
+
+module Liquid
+  class TablerowloopDrop < Drop
+    def initialize(length, cols)
+      @length = length
+      @row = 1
+      @col = 1
+      @cols = cols
+      @index = 0
+    end
+
+    attr_reader :length, :col, :row
+
+    def index
+      @index + 1
+    end
+
+    def index0
+      @index
+    end
+
+    def col0
+      @col - 1
+    end
+
+    def rindex
+      @length - @index
+    end
+
+    def rindex0
+      @length - @index - 1
+    end
+
+    def first
+      @index == 0
+    end
+
+    def last
+      @index == @length - 1
+    end
+
+    def col_first
+      @col == 1
+    end
+
+    def col_last
+      @col == @cols
+    end
+
+    protected
+
+    def increment!
+      @index += 1
+
+      if @col == @cols
+        @col = 1
+        @row += 1
+      else
+        @col += 1
+      end
+    end
+  end
+end

lib/liquid/tag.rb

@@ -1,61 +1,52 @@
+# frozen_string_literal: true
+
 module Liquid
   class Tag
-    attr_accessor :options
-    attr_reader :nodelist, :warnings
+    attr_reader :nodelist, :tag_name, :line_number, :parse_context
+    alias_method :options, :parse_context
+    include ParserSwitching
 
     class << self
-      def parse(tag_name, markup, tokens, options)
+      def parse(tag_name, markup, tokenizer, options)
         tag = new(tag_name, markup, options)
-        tag.parse(tokens)
+        tag.parse(tokenizer)
         tag
       end
 
       private :new
     end
 
-    def initialize(tag_name, markup, options)
+    def initialize(tag_name, markup, parse_context)
       @tag_name   = tag_name
       @markup     = markup
-      @options    = options
+      @parse_context = parse_context
+      @line_number = parse_context.line_number
     end
 
-    def parse(tokens)
+    def parse(_tokens); end
+
+    def raw
+      "#{@tag_name} #{@markup}"
     end
 
     def name
       self.class.name.downcase
     end
 
-    def render(context)
-      ''.freeze
+    def render(_context)
+      ''
+    end
+
+    # For backwards compatibility with custom tags. In a future release, the semantics
+    # of the `render_to_output_buffer` method will become the default and the `render`
+    # method will be removed.
+    def render_to_output_buffer(context, output)
+      output << render(context)
+      output
     end
 
     def blank?
       false
     end
-
-    def parse_with_selected_parser(markup)
-      case @options[:error_mode] || Template.error_mode
-      when :strict then strict_parse_with_error_context(markup)
-      when :lax    then lax_parse(markup)
-      when :warn
-        begin
-          return strict_parse_with_error_context(markup)
-        rescue SyntaxError => e
-          @warnings ||= []
-          @warnings << e
-          return lax_parse(markup)
-        end
-      end
-    end
-
-    private
-
-    def strict_parse_with_error_context(markup)
-      strict_parse(markup)
-    rescue SyntaxError => e
-      e.message << " in \"#{markup.strip}\"" 
-      raise e
-    end
   end
 end

lib/liquid/tags/assign.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # Assign sets a variable in your template.
   #
   #   {% assign foo = 'monkey' %}
@@ -9,29 +10,52 @@ module Liquid
   #  {{ foo }}
   #
   class Assign < Tag
-    Syntax = /(#{VariableSignature}+)\s*=\s*(.*)\s*/om
+    SYNTAX = /(#{VARIABLE_SIGNATURE}+)\s*=\s*(.*)\s*/om.freeze
+
+    attr_reader :to, :from
 
     def initialize(tag_name, markup, options)
       super
-      if markup =~ Syntax
-        @to = $1
-        @from = Variable.new($2)
+      if markup =~ SYNTAX
+        @to = Regexp.last_match(1)
+        @from = Variable.new(Regexp.last_match(2), options)
       else
-        raise SyntaxError.new options[:locale].t("errors.syntax.assign".freeze)
+        raise SyntaxError, options[:locale].t('errors.syntax.assign')
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       val = @from.render(context)
       context.scopes.last[@to] = val
-      context.increment_used_resources(:assign_score_current, val)
-      ''.freeze
+      context.resource_limits.assign_score += assign_score_of(val)
+      output
     end
 
     def blank?
       true
     end
+
+    private
+
+    def assign_score_of(val)
+      if val.instance_of?(String)
+        val.bytesize
+      elsif val.instance_of?(Array) || val.instance_of?(Hash)
+        sum = 1
+        # Uses #each to avoid extra allocations.
+        val.each { |child| sum += assign_score_of(child) }
+        sum
+      else
+        1
+      end
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.from]
+      end
+    end
   end
 
-  Template.register_tag('assign'.freeze, Assign)
+  Template.register_tag('assign', Assign)
 end

lib/liquid/tags/break.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # Break tag to be used to break out of a for loop.
   #
   # == Basic Usage:
@@ -10,12 +11,10 @@ module Liquid
   #    {% endfor %}
   #
   class Break < Tag
-
     def interrupt
       BreakInterrupt.new
     end
-
   end
 
-  Template.register_tag('break'.freeze, Break)
+  Template.register_tag('break', Break)
 end

lib/liquid/tags/capture.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Capture stores the result of a block into a variable without rendering it inplace.
   #
@@ -11,22 +13,23 @@ module Liquid
   # in a sidebar or footer.
   #
   class Capture < Block
-    Syntax = /(\w+)/
+    SYNTAX = /(#{VARIABLE_SIGNATURE}+)/o.freeze
 
     def initialize(tag_name, markup, options)
       super
-      if markup =~ Syntax
-        @to = $1
+      if markup =~ SYNTAX
+        @to = Regexp.last_match(1)
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.capture"))
+        raise SyntaxError, options[:locale].t('errors.syntax.capture')
       end
     end
 
-    def render(context)
-      output = super
+    def render_to_output_buffer(context, output)
+      previous_output_size = output.bytesize
+      super
       context.scopes.last[@to] = output
-      context.increment_used_resources(:assign_score_current, output)
-      ''.freeze
+      context.resource_limits.assign_score += (output.bytesize - previous_output_size)
+      output
     end
 
     def blank?
@@ -34,5 +37,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('capture'.freeze, Capture)
+  Template.register_tag('capture', Capture)
 end

lib/liquid/tags/case.rb

@@ -1,79 +1,90 @@
+# frozen_string_literal: true
+
 module Liquid
   class Case < Block
-    Syntax     = /(#{QuotedFragment})/o
-    WhenSyntax = /(#{QuotedFragment})(?:(?:\s+or\s+|\s*\,\s*)(#{QuotedFragment}.*))?/om
+    SYNTAX = /(#{QUOTED_FRAGMENT})/o.freeze
+    WHEN_SYNTAX = /(#{QUOTED_FRAGMENT})(?:(?:\s+or\s+|\s*\,\s*)(#{QUOTED_FRAGMENT}.*))?/om.freeze
+
+    attr_reader :blocks, :left
 
     def initialize(tag_name, markup, options)
       super
       @blocks = []
 
-      if markup =~ Syntax
-        @left = $1
+      if markup =~ SYNTAX
+        @left = Expression.parse(Regexp.last_match(1))
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.case".freeze))
+        raise SyntaxError, options[:locale].t('errors.syntax.case')
       end
     end
 
+    def parse(tokens)
+      body = BlockBody.new
+      body = @blocks.last.attachment while parse_body(body, tokens)
+    end
+
     def nodelist
-      @blocks.map(&:attachment).flatten
+      @blocks.map(&:attachment)
     end
 
     def unknown_tag(tag, markup, tokens)
-      @nodelist = []
       case tag
-      when 'when'.freeze
+      when 'when'
         record_when_condition(markup)
-      when 'else'.freeze
+      when 'else'
         record_else_condition(markup)
       else
         super
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
         execute_else_block = true
 
-        output = ''
         @blocks.each do |block|
           if block.else?
-            return render_all(block.attachment, context) if execute_else_block
+            block.attachment.render_to_output_buffer(context, output) if execute_else_block
           elsif block.evaluate(context)
             execute_else_block = false
-            output << render_all(block.attachment, context)
+            block.attachment.render_to_output_buffer(context, output)
           end
         end
-        output
       end
+
+      output
     end
 
     private
 
     def record_when_condition(markup)
+      body = BlockBody.new
+
       while markup
-        # Create a new nodelist and assign it to the new block
-        if not markup =~ WhenSyntax
-          raise SyntaxError.new(options[:locale].t("errors.syntax.case_invalid_when".freeze))
-        end
+        raise SyntaxError, options[:locale].t('errors.syntax.case_invalid_when') unless markup =~ WHEN_SYNTAX
 
-        markup = $2
+        markup = Regexp.last_match(2)
 
-        block = Condition.new(@left, '=='.freeze, $1)
-        block.attach(@nodelist)
-        @blocks.push(block)
+        block = Condition.new(@left, '==', Expression.parse(Regexp.last_match(1)))
+        block.attach(body)
+        @blocks << block
       end
     end
 
     def record_else_condition(markup)
-      if not markup.strip.empty?
-        raise SyntaxError.new(options[:locale].t("errors.syntax.case_invalid_else".freeze))
-      end
+      raise SyntaxError, options[:locale].t('errors.syntax.case_invalid_else') unless markup.strip.empty?
 
       block = ElseCondition.new
-      block.attach(@nodelist)
+      block.attach(BlockBody.new)
       @blocks << block
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.left] + @node.blocks
+      end
+    end
   end
 
-  Template.register_tag('case'.freeze, Case)
+  Template.register_tag('case', Case)
 end

lib/liquid/tags/comment.rb

@@ -1,16 +1,17 @@
+# frozen_string_literal: true
+
 module Liquid
   class Comment < Block
-    def render(context)
-      ''.freeze
+    def render_to_output_buffer(_context, output)
+      output
     end
 
-    def unknown_tag(tag, markup, tokens)
-    end
+    def unknown_tag(_tag, _markup, _tokens); end
 
     def blank?
       true
     end
   end
 
-  Template.register_tag('comment'.freeze, Comment)
+  Template.register_tag('comment', Comment)
 end

lib/liquid/tags/continue.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Continue tag to be used to break out of a for loop.
   #
@@ -14,5 +16,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('continue'.freeze, Continue)
+  Template.register_tag('continue', Continue)
 end

lib/liquid/tags/cycle.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Cycle is usually used within a loop to alternate between values, like colors or DOM classes.
   #
@@ -12,45 +14,64 @@ module Liquid
   #    <div class="green"> Item five</div>
   #
   class Cycle < Tag
-    SimpleSyntax = /\A#{QuotedFragment}+/o
-    NamedSyntax  = /\A(#{QuotedFragment})\s*\:\s*(.*)/om
+    SIMPLE_SYNTAX = /\A#{QUOTED_FRAGMENT}+/o.freeze
+    NAMED_SYNTAX  = /\A(#{QUOTED_FRAGMENT})\s*\:\s*(.*)/om.freeze
+
+    attr_reader :variables
 
     def initialize(tag_name, markup, options)
       super
       case markup
-      when NamedSyntax
-        @variables = variables_from_string($2)
-        @name = $1
-      when SimpleSyntax
+      when NAMED_SYNTAX
+        @variables = variables_from_string(Regexp.last_match(2))
+        @name = Expression.parse(Regexp.last_match(1))
+      when SIMPLE_SYNTAX
         @variables = variables_from_string(markup)
-        @name = "'#{@variables.to_s}'"
+        @name = @variables.to_s
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.cycle".freeze))
+        raise SyntaxError, options[:locale].t('errors.syntax.cycle')
       end
     end
 
-    def render(context)
-      context.registers[:cycle] ||= Hash.new(0)
+    def render_to_output_buffer(context, output)
+      context.registers[:cycle] ||= {}
 
       context.stack do
-        key = context[@name]
-        iteration = context.registers[:cycle][key]
-        result = context[@variables[iteration]]
+        key = context.evaluate(@name)
+        iteration = context.registers[:cycle][key].to_i
+
+        val = context.evaluate(@variables[iteration])
+
+        if val.is_a?(Array)
+          val = val.join
+        elsif !val.is_a?(String)
+          val = val.to_s
+        end
+
+        output << val
+
         iteration += 1
-        iteration  = 0  if iteration >= @variables.size
+        iteration  = 0 if iteration >= @variables.size
         context.registers[:cycle][key] = iteration
-        result
       end
+
+      output
     end
 
     private
 
     def variables_from_string(markup)
       markup.split(',').collect do |var|
-        var =~ /\s*(#{QuotedFragment})\s*/o
-        $1 ? $1 : nil
+        var =~ /\s*(#{QUOTED_FRAGMENT})\s*/o
+        Regexp.last_match(1) ? Expression.parse(Regexp.last_match(1)) : nil
       end.compact
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        Array(@node.variables)
+      end
+    end
   end
 
   Template.register_tag('cycle', Cycle)

lib/liquid/tags/decrement.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # decrement is used in a place where one needs to insert a counter
   #     into a template, and needs the counter to survive across
   #     multiple instantiations of the template.
@@ -24,15 +25,14 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
-      value = value - 1
+      value -= 1
       context.environments.first[@variable] = value
-      value.to_s
+      output << value.to_s
+      output
     end
-
-    private
   end
 
-  Template.register_tag('decrement'.freeze, Decrement)
+  Template.register_tag('decrement', Decrement)
 end

lib/liquid/tags/for.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # "For" iterates over an array or collection.
   # Several useful variables are available to you within the loop.
   #
@@ -24,7 +25,7 @@ module Liquid
   #      {{ item.name }}
   #    {% end %}
   #
-  #  To reverse the for loop simply use {% for item in collection reversed %}
+  #  To reverse the for loop simply use {% for item in collection reversed %} (note that the flag's spelling is different to the filter `reverse`)
   #
   # == Available variables:
   #
@@ -42,134 +43,180 @@ module Liquid
   #                   where 0 is the last item.
   # forloop.first:: Returns true if the item is the first item.
   # forloop.last:: Returns true if the item is the last item.
+  # forloop.parentloop:: Provides access to the parent loop, if present.
   #
   class For < Block
-    Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
+    SYNTAX = /\A(#{VARIABLE_SEGMENT}+)\s+in\s+(#{QUOTED_FRAGMENT}+)\s*(reversed)?/o.freeze
+
+    attr_reader :collection_name, :variable_name, :limit, :from
 
     def initialize(tag_name, markup, options)
       super
+      @from = @limit = nil
       parse_with_selected_parser(markup)
-      @nodelist = @for_block = []
+      @for_block = BlockBody.new
+      @else_block = nil
+    end
+
+    def parse(tokens)
+      return unless parse_body(@for_block, tokens)
+
+      parse_body(@else_block, tokens)
     end
 
     def nodelist
-      if @else_block
-        @for_block + @else_block
-      else
-        @for_block
-      end
+      @else_block ? [@for_block, @else_block] : [@for_block]
     end
 
     def unknown_tag(tag, markup, tokens)
-      return super unless tag == 'else'.freeze
-      @nodelist = @else_block = []
+      return super unless tag == 'else'
+
+      @else_block = BlockBody.new
     end
 
-    def render(context)
-      context.registers[:for] ||= Hash.new(0)
+    def render_to_output_buffer(context, output)
+      segment = collection_segment(context)
 
-      collection = context[@collection_name]
-      collection = collection.to_a if collection.is_a?(Range)
-
-      # Maintains Ruby 1.8.7 String#each behaviour on 1.9
-      return render_else(context) unless iterable?(collection)
-
-      from = if @attributes['offset'.freeze] == 'continue'.freeze
-        context.registers[:for][@name].to_i
+      if segment.empty?
+        render_else(context, output)
       else
-        context[@attributes['offset'.freeze]].to_i
+        render_segment(context, output, segment)
       end
 
-      limit = context[@attributes['limit'.freeze]]
-      to    = limit ? limit.to_i + from : nil
-
-      segment = Utils.slice_collection(collection, from, to)
-
-      return render_else(context) if segment.empty?
-
-      segment.reverse! if @reversed
-
-      result = ''
-
-      length = segment.length
-
-      # Store our progress through the collection for the continue flag
-      context.registers[:for][@name] = from + segment.length
-
-      context.stack do
-        segment.each_with_index do |item, index|
-          context[@variable_name] = item
-          context['forloop'.freeze] = {
-            'name'.freeze    => @name,
-            'length'.freeze  => length,
-            'index'.freeze   => index + 1,
-            'index0'.freeze  => index,
-            'rindex'.freeze  => length - index,
-            'rindex0'.freeze => length - index - 1,
-            'first'.freeze   => (index == 0),
-            'last'.freeze    => (index == length - 1)
-          }
-
-          result << render_all(@for_block, context)
-
-          # Handle any interrupts if they exist.
-          if context.has_interrupt?
-            interrupt = context.pop_interrupt
-            break if interrupt.is_a? BreakInterrupt
-            next if interrupt.is_a? ContinueInterrupt
-          end
-        end
-      end
-      result
+      output
     end
 
     protected
 
     def lax_parse(markup)
-      if markup =~ Syntax
-        @variable_name = $1
-        @collection_name = $2
-        @name = "#{$1}-#{$2}"
-        @reversed = $3
-        @attributes = {}
-        markup.scan(TagAttributes) do |key, value|
-          @attributes[key] = value
+      if markup =~ SYNTAX
+        @variable_name = Regexp.last_match(1)
+        collection_name = Regexp.last_match(2)
+        @reversed = !!Regexp.last_match(3)
+        @name = "#{@variable_name}-#{collection_name}"
+        @collection_name = Expression.parse(collection_name)
+        markup.scan(TAG_ATTRIBUTES) do |key, value|
+          set_attribute(key, value)
         end
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.for".freeze))
+        raise SyntaxError, options[:locale].t('errors.syntax.for')
       end
     end
 
     def strict_parse(markup)
       p = Parser.new(markup)
       @variable_name = p.consume(:id)
-      raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_in".freeze))  unless p.id?('in'.freeze)
-      @collection_name = p.expression
-      @name = "#{@variable_name}-#{@collection_name}"
-      @reversed = p.id?('reversed'.freeze)
+      raise SyntaxError, options[:locale].t('errors.syntax.for_invalid_in') unless p.id?('in')
+
+      collection_name = p.expression
+      @name = "#{@variable_name}-#{collection_name}"
+      @collection_name = Expression.parse(collection_name)
+      @reversed = p.id?('reversed')
 
-      @attributes = {}
       while p.look(:id) && p.look(:colon, 1)
-        unless attribute = p.id?('limit'.freeze) || p.id?('offset'.freeze)
-          raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_attribute".freeze))
+        unless (attribute = p.id?('limit') || p.id?('offset'))
+          raise SyntaxError, options[:locale].t('errors.syntax.for_invalid_attribute')
         end
+
         p.consume
-        val = p.expression
-        @attributes[attribute] = val
+        set_attribute(attribute, p.expression)
       end
       p.consume(:end_of_string)
     end
 
     private
 
-    def render_else(context)
-      return @else_block ? [render_all(@else_block, context)] : ''.freeze
+    def collection_segment(context)
+      offsets = context.registers[:for] ||= {}
+
+      from = if @from == :continue
+        offsets[@name].to_i
+      else
+        from_value = context.evaluate(@from)
+        if from_value.nil?
+          0
+        else
+          Utils.to_integer(from_value)
+        end
+      end
+
+      collection = context.evaluate(@collection_name)
+      collection = collection.to_a if collection.is_a?(Range)
+
+      limit_value = context.evaluate(@limit)
+      to = if limit_value.nil?
+        nil
+      else
+        Utils.to_integer(limit_value) + from
+      end
+
+      segment = Utils.slice_collection(collection, from, to)
+      segment.reverse! if @reversed
+
+      offsets[@name] = from + segment.length
+
+      segment
     end
 
-    def iterable?(collection)
-      collection.respond_to?(:each) || Utils.non_blank_string?(collection)
+    def render_segment(context, output, segment)
+      for_stack = context.registers[:for_stack] ||= []
+      length = segment.length
+
+      context.stack do
+        loop_vars = Liquid::ForloopDrop.new(@name, length, for_stack[-1])
+
+        for_stack.push(loop_vars)
+
+        begin
+          context['forloop'] = loop_vars
+
+          segment.each do |item|
+            context[@variable_name] = item
+            @for_block.render_to_output_buffer(context, output)
+            loop_vars.send(:increment!)
+
+            # Handle any interrupts if they exist.
+            next unless context.interrupt?
+
+            interrupt = context.pop_interrupt
+            break if interrupt.is_a?(BreakInterrupt)
+            next if interrupt.is_a?(ContinueInterrupt)
+          end
+        ensure
+          for_stack.pop
+        end
+      end
+
+      output
+    end
+
+    def set_attribute(key, expr)
+      case key
+      when 'offset'
+        @from = if expr == 'continue'
+          :continue
+        else
+          Expression.parse(expr)
+        end
+      when 'limit'
+        @limit = Expression.parse(expr)
+      end
+    end
+
+    def render_else(context, output)
+      if @else_block
+        @else_block.render_to_output_buffer(context, output)
+      else
+        output
+      end
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        (super + [@node.limit, @node.from, @node.collection_name]).compact
+      end
     end
   end
 
-  Template.register_tag('for'.freeze, For)
+  Template.register_tag('for', For)
 end

lib/liquid/tags/if.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # If is the conditional block
   #
@@ -10,97 +12,113 @@ module Liquid
   #    There are {% if count < 5 %} less {% else %} more {% endif %} items than you need.
   #
   class If < Block
-    Syntax = /(#{QuotedFragment})\s*([=!<>a-z_]+)?\s*(#{QuotedFragment})?/o
-    ExpressionsAndOperators = /(?:\b(?:\s?and\s?|\s?or\s?)\b|(?:\s*(?!\b(?:\s?and\s?|\s?or\s?)\b)(?:#{QuotedFragment}|\S+)\s*)+)/o
-    BOOLEAN_OPERATORS = %w(and or)
+    SYNTAX = /(#{QUOTED_FRAGMENT})\s*([=!<>a-z_]+)?\s*(#{QUOTED_FRAGMENT})?/o.freeze
+    EXPRESSIONS_AND_OPERATORS = /(?:\b(?:\s?and\s?|\s?or\s?)\b|(?:\s*(?!\b(?:\s?and\s?|\s?or\s?)\b)(?:#{QUOTED_FRAGMENT}|\S+)\s*)+)/o.freeze
+    BOOLEAN_OPERATORS = %w[and or].freeze
+
+    attr_reader :blocks
 
     def initialize(tag_name, markup, options)
       super
       @blocks = []
-      push_block('if'.freeze, markup)
+      push_block('if', markup)
     end
 
     def nodelist
-      @blocks.map(&:attachment).flatten
+      @blocks.map(&:attachment)
+    end
+
+    def parse(tokens)
+      while parse_body(@blocks.last.attachment, tokens)
+      end
     end
 
     def unknown_tag(tag, markup, tokens)
-      if ['elsif'.freeze, 'else'.freeze].include?(tag)
+      if %w[elsif else].include?(tag)
         push_block(tag, markup)
       else
         super
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
         @blocks.each do |block|
-          if block.evaluate(context)
-            return render_all(block.attachment, context)
-          end
+          return block.attachment.render_to_output_buffer(context, output) if block.evaluate(context)
         end
-        ''.freeze
       end
+
+      output
     end
 
     private
 
-      def push_block(tag, markup)
-        block = if tag == 'else'.freeze
-          ElseCondition.new
-        else
-          parse_with_selected_parser(markup)
-        end
-
-        @blocks.push(block)
-        @nodelist = block.attach(Array.new)
+    def push_block(tag, markup)
+      block = if tag == 'else'
+        ElseCondition.new
+      else
+        parse_with_selected_parser(markup)
       end
 
-      def lax_parse(markup)
-        expressions = markup.scan(ExpressionsAndOperators).reverse
-        raise(SyntaxError.new(options[:locale].t("errors.syntax.if".freeze))) unless expressions.shift =~ Syntax
+      @blocks.push(block)
+      block.attach(BlockBody.new)
+    end
 
-        condition = Condition.new($1, $2, $3)
+    def lax_parse(markup)
+      expressions = markup.scan(EXPRESSIONS_AND_OPERATORS)
+      raise SyntaxError, options[:locale].t('errors.syntax.if') unless expressions.pop =~ SYNTAX
 
-        while not expressions.empty?
-          operator = (expressions.shift).to_s.strip
+      condition = Condition.new(Expression.parse(Regexp.last_match(1)), Regexp.last_match(2), Expression.parse(Regexp.last_match(3)))
 
-          raise(SyntaxError.new(options[:locale].t("errors.syntax.if".freeze))) unless expressions.shift.to_s =~ Syntax
+      until expressions.empty?
+        operator = expressions.pop.to_s.strip
 
-          new_condition = Condition.new($1, $2, $3)
-          raise(SyntaxError.new(options[:locale].t("errors.syntax.if".freeze))) unless BOOLEAN_OPERATORS.include?(operator)
-          new_condition.send(operator, condition)
-          condition = new_condition
-        end
+        raise SyntaxError, options[:locale].t('errors.syntax.if') unless expressions.pop.to_s =~ SYNTAX
 
-        condition
+        new_condition = Condition.new(Expression.parse(Regexp.last_match(1)), Regexp.last_match(2), Expression.parse(Regexp.last_match(3)))
+        raise SyntaxError, options[:locale].t('errors.syntax.if') unless BOOLEAN_OPERATORS.include?(operator)
+
+        new_condition.send(operator, condition)
+        condition = new_condition
       end
 
-      def strict_parse(markup)
-        p = Parser.new(markup)
+      condition
+    end
 
-        condition = parse_comparison(p)
+    def strict_parse(markup)
+      p = Parser.new(markup)
+      condition = parse_binary_comparisons(p)
+      p.consume(:end_of_string)
+      condition
+    end
 
-        while op = (p.id?('and'.freeze) || p.id?('or'.freeze))
-          new_cond = parse_comparison(p)
-          new_cond.send(op, condition)
-          condition = new_cond
-        end
-        p.consume(:end_of_string)
-
-        condition
+    def parse_binary_comparisons(p)
+      condition = parse_comparison(p)
+      first_condition = condition
+      while (op = (p.id?('and') || p.id?('or')))
+        child_condition = parse_comparison(p)
+        condition.send(op, child_condition)
+        condition = child_condition
       end
+      first_condition
+    end
 
-      def parse_comparison(p)
-        a = p.expression
-        if op = p.consume?(:comparison)
-          b = p.expression
-          Condition.new(a, op, b)
-        else
-          Condition.new(a)
-        end
+    def parse_comparison(p)
+      a = Expression.parse(p.expression)
+      if (op = p.consume?(:comparison))
+        b = Expression.parse(p.expression)
+        Condition.new(a, op, b)
+      else
+        Condition.new(a)
       end
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        @node.blocks
+      end
+    end
   end
 
-  Template.register_tag('if'.freeze, If)
+  Template.register_tag('if', If)
 end

lib/liquid/tags/ifchanged.rb

@@ -1,20 +1,21 @@
+# frozen_string_literal: true
+
 module Liquid
   class Ifchanged < Block
-
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
+        block_output = +''
+        super(context, block_output)
 
-        output = render_all(@nodelist, context)
-
-        if output != context.registers[:ifchanged]
-          context.registers[:ifchanged] = output
-          output
-        else
-          ''.freeze
+        if block_output != context.registers[:ifchanged]
+          context.registers[:ifchanged] = block_output
+          output << block_output
         end
       end
+
+      output
     end
   end
 
-  Template.register_tag('ifchanged'.freeze, Ifchanged)
+  Template.register_tag('ifchanged', Ifchanged)
 end

lib/liquid/tags/include.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # Include allows templates to relate with other templates
   #
   # Simply include another template:
@@ -15,80 +16,113 @@ module Liquid
   #   {% include 'product' for products %}
   #
   class Include < Tag
-    Syntax = /(#{QuotedFragment}+)(\s+(?:with|for)\s+(#{QuotedFragment}+))?/o
+    SYNTAX = /(#{QUOTED_FRAGMENT}+)(\s+(?:with|for)\s+(#{QUOTED_FRAGMENT}+))?/o.freeze
+
+    attr_reader :template_name_expr, :variable_name_expr, :attributes
 
     def initialize(tag_name, markup, options)
       super
 
-      if markup =~ Syntax
+      if markup =~ SYNTAX
 
-        @template_name = $1
-        @variable_name = $3
-        @attributes    = {}
+        template_name = Regexp.last_match(1)
+        variable_name = Regexp.last_match(3)
 
-        markup.scan(TagAttributes) do |key, value|
-          @attributes[key] = value
+        @variable_name_expr = variable_name ? Expression.parse(variable_name) : nil
+        @template_name_expr = Expression.parse(template_name)
+        @attributes = {}
+
+        markup.scan(TAG_ATTRIBUTES) do |key, value|
+          @attributes[key] = Expression.parse(value)
         end
 
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.include".freeze))
+        raise SyntaxError, options[:locale].t('errors.syntax.include')
       end
     end
 
-    def parse(tokens)
-    end
+    def parse(_tokens); end
 
-    def render(context)
-      partial = load_cached_partial(context)
-      variable = context[@variable_name || @template_name[1..-2]]
+    def render_to_output_buffer(context, output)
+      template_name = context.evaluate(@template_name_expr)
+      raise ArgumentError, options[:locale].t('errors.argument.include') unless template_name
 
-      context.stack do
-        @attributes.each do |key, value|
-          context[key] = context[value]
-        end
+      partial = load_cached_partial(template_name, context)
+      context_variable_name = template_name.split('/').last
 
-        context_variable_name = @template_name[1..-2].split('/'.freeze).last
-        if variable.is_a?(Array)
-          variable.collect do |var|
-            context[context_variable_name] = var
-            partial.render(context)
+      variable = if @variable_name_expr
+        context.evaluate(@variable_name_expr)
+      else
+        context.find_variable(template_name, raise_on_not_found: false)
+      end
+
+      old_template_name = context.template_name
+      old_partial = context.partial
+      begin
+        context.template_name = template_name
+        context.partial = true
+        context.stack do
+          @attributes.each do |key, value|
+            context[key] = context.evaluate(value)
+          end
+
+          if variable.is_a?(Array)
+            variable.each do |var|
+              context[context_variable_name] = var
+              partial.render_to_output_buffer(context, output)
+            end
+          else
+            context[context_variable_name] = variable
+            partial.render_to_output_buffer(context, output)
           end
-        else
-          context[context_variable_name] = variable
-          partial.render(context)
         end
+      ensure
+        context.template_name = old_template_name
+        context.partial = old_partial
       end
+
+      output
     end
 
     private
-      def load_cached_partial(context)
-        cached_partials = context.registers[:cached_partials] || {}
-        template_name = context[@template_name]
 
-        if cached = cached_partials[template_name]
-          return cached
-        end
-        source = read_template_from_file_system(context)
-        partial = Liquid::Template.parse(source)
-        cached_partials[template_name] = partial
-        context.registers[:cached_partials] = cached_partials
-        partial
+    alias_method :parse_context, :options
+    private :parse_context
+
+    def load_cached_partial(template_name, context)
+      cached_partials = context.registers[:cached_partials] || {}
+
+      if (cached = cached_partials[template_name])
+        return cached
       end
 
-      def read_template_from_file_system(context)
-        file_system = context.registers[:file_system] || Liquid::Template.file_system
-
-        # make read_template_file call backwards-compatible.
-        case file_system.method(:read_template_file).arity
-        when 1
-          file_system.read_template_file(context[@template_name])
-        when 2
-          file_system.read_template_file(context[@template_name], context)
-        else
-          raise ArgumentError, "file_system.read_template_file expects two parameters: (template_name, context)"
-        end
+      source = read_template_from_file_system(context)
+      begin
+        parse_context.partial = true
+        partial = Liquid::Template.parse(source, parse_context)
+      ensure
+        parse_context.partial = false
       end
+      cached_partials[template_name] = partial
+      context.registers[:cached_partials] = cached_partials
+      partial
+    end
+
+    def read_template_from_file_system(context)
+      file_system = context.registers[:file_system] || Liquid::Template.file_system
+
+      file_system.read_template_file(context.evaluate(@template_name_expr))
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.template_name_expr,
+          @node.variable_name_expr,
+        ] + @node.attributes.values
+      end
+    end
   end
 
-  Template.register_tag('include'.freeze, Include)
+  Template.register_tag('include', Include)
 end

lib/liquid/tags/increment.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # increment is used in a place where one needs to insert a counter
   #     into a template, and needs the counter to survive across
@@ -20,12 +22,13 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
       context.environments.first[@variable] = value + 1
-      value.to_s
+      output << value.to_s
+      output
     end
   end
 
-  Template.register_tag('increment'.freeze, Increment)
+  Template.register_tag('increment', Increment)
 end

lib/liquid/tags/raw.rb

@@ -1,22 +1,48 @@
+# frozen_string_literal: true
+
 module Liquid
   class Raw < Block
-    FullTokenPossiblyInvalid = /\A(.*)#{TagStart}\s*(\w+)\s*(.*)?#{TagEnd}\z/om
+    SYNTAX = /\A\s*\z/.freeze
+    FULL_TOKEN_POSSIBLY_INVALID = /\A(.*)#{TAG_START}\s*(\w+)\s*(.*)?#{TAG_END}\z/om.freeze
+
+    def initialize(tag_name, markup, parse_context)
+      super
+
+      ensure_valid_markup(tag_name, markup, parse_context)
+    end
 
     def parse(tokens)
-      @nodelist ||= []
-      @nodelist.clear
-      while token = tokens.shift
-        if token =~ FullTokenPossiblyInvalid
-          @nodelist << $1 if $1 != "".freeze
-          if block_delimiter == $2
-            end_tag
-            return
-          end
+      @body = +''
+      while (token = tokens.shift)
+        if token =~ FULL_TOKEN_POSSIBLY_INVALID
+          @body << Regexp.last_match(1) if Regexp.last_match(1) != ''
+          return if block_delimiter == Regexp.last_match(2)
         end
-        @nodelist << token if not token.empty?
+        @body << token unless token.empty?
       end
+
+      raise SyntaxError, parse_context.locale.t('errors.syntax.tag_never_closed', block_name: block_name)
+    end
+
+    def render_to_output_buffer(_context, output)
+      output << @body
+      output
+    end
+
+    def nodelist
+      [@body]
+    end
+
+    def blank?
+      @body.empty?
+    end
+
+    protected
+
+    def ensure_valid_markup(tag_name, markup, parse_context)
+      raise SyntaxError, parse_context.locale.t('errors.syntax.tag_unexpected_args', tag: tag_name) unless markup =~ SYNTAX
     end
   end
 
-  Template.register_tag('raw'.freeze, Raw)
+  Template.register_tag('raw', Raw)
 end

lib/liquid/tags/table_row.rb

@@ -1,73 +1,65 @@
+# frozen_string_literal: true
+
 module Liquid
   class TableRow < Block
-    Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)/o
+    SYNTAX = /(\w+)\s+in\s+(#{QUOTED_FRAGMENT}+)/o.freeze
+
+    attr_reader :variable_name, :collection_name, :attributes
 
     def initialize(tag_name, markup, options)
       super
-      if markup =~ Syntax
-        @variable_name = $1
-        @collection_name = $2
+      if markup =~ SYNTAX
+        @variable_name = Regexp.last_match(1)
+        @collection_name = Expression.parse(Regexp.last_match(2))
         @attributes = {}
-        markup.scan(TagAttributes) do |key, value|
-          @attributes[key] = value
+        markup.scan(TAG_ATTRIBUTES) do |key, value|
+          @attributes[key] = Expression.parse(value)
         end
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.table_row".freeze))
+        raise SyntaxError, options[:locale].t('errors.syntax.table_row')
       end
     end
 
-    def render(context)
-      collection = context[@collection_name] or return ''.freeze
+    def render_to_output_buffer(context, output)
+      (collection = context.evaluate(@collection_name)) || (return '')
 
-      from = @attributes['offset'.freeze] ? context[@attributes['offset'.freeze]].to_i : 0
-      to = @attributes['limit'.freeze] ? from + context[@attributes['limit'.freeze]].to_i : nil
+      from = @attributes.key?('offset') ? context.evaluate(@attributes['offset']).to_i : 0
+      to = @attributes.key?('limit') ? from + context.evaluate(@attributes['limit']).to_i : nil
 
       collection = Utils.slice_collection(collection, from, to)
 
       length = collection.length
 
-      cols = context[@attributes['cols'.freeze]].to_i
+      cols = context.evaluate(@attributes['cols']).to_i
 
-      row = 1
-      col = 0
-
-      result = "<tr class=\"row1\">\n"
+      output << "<tr class=\"row1\">\n"
       context.stack do
+        tablerowloop = Liquid::TablerowloopDrop.new(length, cols)
+        context['tablerowloop'] = tablerowloop
 
-        collection.each_with_index do |item, index|
+        collection.each do |item|
           context[@variable_name] = item
-          context['tablerowloop'.freeze] = {
-            'length'.freeze    => length,
-            'index'.freeze     => index + 1,
-            'index0'.freeze    => index,
-            'col'.freeze       => col + 1,
-            'col0'.freeze      => col,
-            'index0'.freeze    => index,
-            'rindex'.freeze    => length - index,
-            'rindex0'.freeze   => length - index - 1,
-            'first'.freeze     => (index == 0),
-            'last'.freeze      => (index == length - 1),
-            'col_first'.freeze => (col == 0),
-            'col_last'.freeze  => (col == cols - 1)
-          }
 
+          output << "<td class=\"col#{tablerowloop.col}\">"
+          super
+          output << '</td>'
 
-          col += 1
-
-          result << "<td class=\"col#{col}\">" << render_all(@nodelist, context) << '</td>'
-
-          if col == cols and (index != length - 1)
-            col  = 0
-            row += 1
-            result << "</tr>\n<tr class=\"row#{row}\">"
-          end
+          output << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">" if tablerowloop.col_last && !tablerowloop.last
 
+          tablerowloop.send(:increment!)
         end
       end
-      result << "</tr>\n"
-      result
+
+      output << "</tr>\n"
+      output
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        super + @node.attributes.values + [@node.collection_name]
+      end
     end
   end
 
-  Template.register_tag('tablerow'.freeze, TableRow)
+  Template.register_tag('tablerow', TableRow)
 end

lib/liquid/tags/unless.rb

@@ -1,31 +1,28 @@
-require File.dirname(__FILE__) + '/if'
+# frozen_string_literal: true
+
+require_relative 'if'
 
 module Liquid
   # Unless is a conditional just like 'if' but works on the inverse logic.
   #
-  #   {% unless x < 0 %} x is greater than zero {% end %}
+  #   {% unless x < 0 %} x is greater than zero {% endunless %}
   #
   class Unless < If
-    def render(context)
+    def render_to_output_buffer(context, output)
       context.stack do
-
         # First condition is interpreted backwards ( if not )
         first_block = @blocks.first
-        unless first_block.evaluate(context)
-          return render_all(first_block.attachment, context)
-        end
+        return first_block.attachment.render_to_output_buffer(context, output) unless first_block.evaluate(context)
 
         # After the first condition unless works just like if
         @blocks[1..-1].each do |block|
-          if block.evaluate(context)
-            return render_all(block.attachment, context)
-          end
+          return block.attachment.render_to_output_buffer(context, output) if block.evaluate(context)
         end
-
-        ''.freeze
       end
+
+      output
     end
   end
 
-  Template.register_tag('unless'.freeze, Unless)
+  Template.register_tag('unless', Unless)
 end

lib/liquid/template.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # Templates are central to liquid.
   # Interpretating templates is a two step process. First you compile the
   # source code you got. During compile time some extensive error checking is performed.
@@ -14,21 +15,25 @@ module Liquid
   #   template.render('user_name' => 'bob')
   #
   class Template
-    DEFAULT_OPTIONS = {
-      :locale => I18n.new
-    }
+    attr_accessor :root
+    attr_reader :resource_limits, :warnings
 
-    attr_accessor :root, :resource_limits
-    @@file_system = BlankFileSystem.new
+    @file_system = BlankFileSystem.new
+
+    class << self
+      attr_accessor :file_system
+    end
 
     class TagRegistry
+      include Enumerable
+
       def initialize
-        @tags  = {}
+        @tags = {}
         @cache = {}
       end
 
       def [](tag_name)
-        return nil unless @tags.has_key?(tag_name)
+        return nil unless @tags.key?(tag_name)
         return @cache[tag_name] if Liquid.cache_classes
 
         lookup_class(@tags[tag_name]).tap { |o| @cache[tag_name] = o }
@@ -44,13 +49,19 @@ module Liquid
         @cache.delete(tag_name)
       end
 
+      def each(&block)
+        @tags.each(&block)
+      end
+
       private
 
       def lookup_class(name)
-        name.split("::").reject(&:empty?).reduce(Object) { |scope, const| scope.const_get(const) }
+        Object.const_get(name)
       end
     end
 
+    attr_reader :profiler
+
     class << self
       # Sets how strict the parser should be.
       # :lax acts like liquid 2.5 and silently ignores malformed tags in most cases.
@@ -58,12 +69,15 @@ module Liquid
       # :strict will enforce correct syntax.
       attr_writer :error_mode
 
-      def file_system
-        @@file_system
-      end
+      # Sets how strict the taint checker should be.
+      # :lax is the default, and ignores the taint flag completely
+      # :warn adds a warning, but does not interrupt the rendering
+      # :error raises an error when tainted output is used
+      attr_writer :taint_mode
 
-      def file_system=(obj)
-        @@file_system = obj
+      attr_accessor :default_exception_renderer
+      Template.default_exception_renderer = lambda do |exception|
+        exception
       end
 
       def register_tag(name, klass)
@@ -75,7 +89,11 @@ module Liquid
       end
 
       def error_mode
-        @error_mode || :lax
+        @error_mode ||= :lax
+      end
+
+      def taint_mode
+        @taint_mode ||= :lax
       end
 
       # Pass a module with filter methods which should be available
@@ -84,31 +102,36 @@ module Liquid
         Strainer.global_filter(mod)
       end
 
+      def default_resource_limits
+        @default_resource_limits ||= {}
+      end
+
       # creates a new <tt>Template</tt> object from liquid source code
+      # To enable profiling, pass in <tt>profile: true</tt> as an option.
+      # See Liquid::Profiler for more information
       def parse(source, options = {})
         template = Template.new
         template.parse(source, options)
       end
     end
 
-    # creates a new <tt>Template</tt> from an array of tokens. Use <tt>Template.parse</tt> instead
     def initialize
-      @resource_limits = {}
+      @rethrow_errors = false
+      @resource_limits = ResourceLimits.new(self.class.default_resource_limits)
     end
 
     # Parse source code.
     # Returns self for easy chaining
     def parse(source, options = {})
-      @root = Document.parse(tokenize(source), DEFAULT_OPTIONS.merge(options))
-      @warnings = nil
+      @options = options
+      @profiling = options[:profile]
+      @line_numbers = options[:line_numbers] || @profiling
+      parse_context = options.is_a?(ParseContext) ? options : ParseContext.new(options)
+      @root = Document.parse(tokenize(source), parse_context)
+      @warnings = parse_context.warnings
       self
     end
 
-    def warnings
-      return [] unless @root
-      @warnings ||= @root.warnings
-    end
-
     def registers
       @registers ||= {}
     end
@@ -130,6 +153,9 @@ module Liquid
     # if you use the same filters over and over again consider registering them globally
     # with <tt>Template.register_filter</tt>
     #
+    # if profiling was enabled in <tt>Template#parse</tt> then the resulting profiling information
+    # will be available via <tt>Template#profiler</tt>
+    #
     # Following options can be passed:
     #
     #  * <tt>filters</tt> : array with local filters
@@ -137,15 +163,13 @@ module Liquid
     #    filters and tags and might be useful to integrate liquid more with its host application
     #
     def render(*args)
-      return ''.freeze if @root.nil?
+      return '' if @root.nil?
 
       context = case args.first
       when Liquid::Context
         c = args.shift
 
-        if @rethrow_errors
-          c.exception_handler = ->(e) { true }
-        end
+        c.exception_renderer = ->(_e) { raise } if @rethrow_errors
 
         c
       when Liquid::Drop
@@ -156,35 +180,32 @@ module Liquid
       when nil
         Context.new(assigns, instance_assigns, registers, @rethrow_errors, @resource_limits)
       else
-        raise ArgumentError, "Expected Hash or Liquid::Context as parameter"
+        raise ArgumentError, 'Expected Hash or Liquid::Context as parameter'
       end
 
+      output = nil
+
       case args.last
       when Hash
         options = args.pop
+        output = options[:output] if options[:output]
 
-        if options[:registers].is_a?(Hash)
-          self.registers.merge!(options[:registers])
-        end
+        registers.merge!(options[:registers]) if options[:registers].is_a?(Hash)
 
-        if options[:filters]
-          context.add_filters(options[:filters])
-        end
-
-        if options[:exception_handler]
-          context.exception_handler = options[:exception_handler]
-        end
-      when Module
-        context.add_filters(args.pop)
-      when Array
+        apply_options_to_context(context, options)
+      when Module, Array
         context.add_filters(args.pop)
       end
 
+      # Retrying a render resets resource usage
+      context.resource_limits.reset
+
       begin
         # render the nodelist.
         # for performance reasons we get an array back here. join will make a string out of it.
-        result = @root.render(context)
-        result.respond_to?(:join) ? result.join : result
+        with_profiling(context) do
+          @root.render_to_output_buffer(context, output || +'')
+        end
       rescue Liquid::MemoryError => e
         context.handle_error(e)
       ensure
@@ -197,19 +218,39 @@ module Liquid
       render(*args)
     end
 
-    private
-
-    # Uses the <tt>Liquid::TemplateParser</tt> regexp to tokenize the passed source
-    def tokenize(source)
-      source = source.source if source.respond_to?(:source)
-      return [] if source.to_s.empty?
-      tokens = source.split(TemplateParser)
-
-      # removes the rogue empty element at the beginning of the array
-      tokens.shift if tokens[0] and tokens[0].empty?
-
-      tokens
+    def render_to_output_buffer(context, output)
+      render(context, output: output)
     end
 
+    private
+
+    def tokenize(source)
+      Tokenizer.new(source, @line_numbers)
+    end
+
+    def with_profiling(context)
+      if @profiling && !context.partial
+        raise "Profiler not loaded, require 'liquid/profiler' first" unless defined?(Liquid::Profiler)
+
+        @profiler = Profiler.new
+        @profiler.start
+
+        begin
+          yield
+        ensure
+          @profiler.stop
+        end
+      else
+        yield
+      end
+    end
+
+    def apply_options_to_context(context, options)
+      context.add_filters(options[:filters]) if options[:filters]
+      context.global_filter = options[:global_filter] if options[:global_filter]
+      context.exception_renderer = options[:exception_renderer] if options[:exception_renderer]
+      context.strict_variables = options[:strict_variables] if options[:strict_variables]
+      context.strict_filters = options[:strict_filters] if options[:strict_filters]
+    end
   end
 end

lib/liquid/tokenizer.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+module Liquid
+  class Tokenizer
+    attr_reader :line_number
+
+    def initialize(source, line_numbers = false)
+      @source = source
+      @line_number = line_numbers ? 1 : nil
+      @tokens = tokenize
+    end
+
+    def shift
+      token = @tokens.shift
+      @line_number += token.count("\n") if @line_number && token
+      token
+    end
+
+    private
+
+    def tokenize
+      @source = @source.source if @source.respond_to?(:source)
+      return [] if @source.to_s.empty?
+
+      tokens = @source.split(TEMPLATE_PARSER)
+
+      # removes the rogue empty element at the beginning of the array
+      tokens.shift if tokens[0]&.empty?
+
+      tokens
+    end
+  end
+end

lib/liquid/utils.rb

@@ -1,39 +1,83 @@
+# frozen_string_literal: true
+
 module Liquid
   module Utils
-
     def self.slice_collection(collection, from, to)
-      if (from != 0 || to != nil) && collection.respond_to?(:load_slice)
+      if (from != 0 || !to.nil?) && collection.respond_to?(:load_slice)
         collection.load_slice(from, to)
       else
         slice_collection_using_each(collection, from, to)
       end
     end
 
-    def self.non_blank_string?(collection)
-      collection.is_a?(String) && collection != ''.freeze
-    end
-
     def self.slice_collection_using_each(collection, from, to)
       segments = []
       index = 0
 
       # Maintains Ruby 1.8.7 String#each behaviour on 1.9
-      return [collection] if non_blank_string?(collection)
+      if collection.is_a?(String)
+        return collection.empty? ? [] : [collection]
+      end
+      return [] unless collection.respond_to?(:each)
 
       collection.each do |item|
+        break if to && to <= index
 
-        if to && to <= index
-          break
-        end
-
-        if from <= index
-          segments << item
-        end
+        segments << item if from <= index
 
         index += 1
       end
 
       segments
     end
+
+    def self.to_integer(num)
+      return num if num.is_a?(Integer)
+
+      num = num.to_s
+      begin
+        Integer(num)
+      rescue ::ArgumentError
+        raise Liquid::ArgumentError, 'invalid integer'
+      end
+    end
+
+    def self.to_number(obj)
+      case obj
+      when Float
+        BigDecimal(obj.to_s)
+      when Numeric
+        obj
+      when String
+        obj.strip =~ /\A-?\d+\.\d+\z/ ? BigDecimal(obj) : obj.to_i
+      else
+        if obj.respond_to?(:to_number)
+          obj.to_number
+        else
+          0
+        end
+      end
+    end
+
+    def self.to_date(obj)
+      return obj if obj.respond_to?(:strftime)
+
+      if obj.is_a?(String)
+        return nil if obj.empty?
+
+        obj = obj.downcase
+      end
+
+      case obj
+      when 'now', 'today'
+        Time.now
+      when /\A\d+\z/, Integer
+        Time.at(obj.to_i)
+      when String
+        Time.parse(obj)
+      end
+    rescue ::ArgumentError
+      nil
+    end
   end
 end

lib/liquid/variable.rb

@@ -1,5 +1,6 @@
-module Liquid
+# frozen_string_literal: true
 
+module Liquid
   # Holds variables. Variables are only loaded "just in time"
   # and are not evaluated as part of the render stage
   #
@@ -11,97 +12,151 @@ module Liquid
   #   {{ user | link }}
   #
   class Variable
-    FilterParser = /(?:#{FilterSeparator}|(?:\s*(?:#{QuotedFragment}|#{ArgumentSeparator})\s*)+)/o
-    EasyParse = /\A *(\w+(?:\.\w+)*) *\z/
-    attr_accessor :filters, :name, :warnings
+    FILTER_MARKUP_REGEX = /#{FILTER_SEPARATOR}\s*(.*)/om.freeze
+    FILTER_PARSER = /(?:\s+|#{QUOTED_FRAGMENT}|#{ARGUMENT_SEPARATOR})+/o.freeze
+    FILTER_ARGS_REGEX = /(?:#{FILTER_ARGUMENT_SEPARATOR}|#{ARGUMENT_SEPARATOR})\s*((?:\w+\s*\:\s*)?#{QUOTED_FRAGMENT})/o.freeze
+    JUST_TAG_ATTRIBUTES = /\A#{TAG_ATTRIBUTES}\z/o.freeze
+    MARKUP_WITH_QUOTED_FRAGMENT = /(#{QUOTED_FRAGMENT})(.*)/om.freeze
 
-    def initialize(markup, options = {})
+    attr_accessor :filters, :name, :line_number
+    attr_reader :parse_context
+    alias_method :options, :parse_context
+
+    include ParserSwitching
+
+    def initialize(markup, parse_context)
       @markup  = markup
       @name    = nil
-      @options = options || {}
+      @parse_context = parse_context
+      @line_number = parse_context.line_number
 
-      case @options[:error_mode] || Template.error_mode
-      when :strict then strict_parse(markup)
-      when :lax    then lax_parse(markup)
-      when :warn
-        begin
-          strict_parse(markup)
-        rescue SyntaxError => e
-          @warnings ||= []
-          @warnings << e
-          lax_parse(markup)
-        end
-      end
+      parse_with_selected_parser(markup)
+    end
+
+    def raw
+      @markup
+    end
+
+    def markup_context(markup)
+      "in \"{{#{markup}}}\""
     end
 
     def lax_parse(markup)
       @filters = []
-      if markup =~ /\s*(#{QuotedFragment})(.*)/om
-        @name = Regexp.last_match(1)
-        if Regexp.last_match(2) =~ /#{FilterSeparator}\s*(.*)/om
-          filters = Regexp.last_match(1).scan(FilterParser)
-          filters.each do |f|
-            if f =~ /\s*(\w+)/
-              filtername = Regexp.last_match(1)
-              filterargs = f.scan(/(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o).flatten
-              @filters << [filtername, filterargs]
-            end
-          end
+      return unless markup =~ MARKUP_WITH_QUOTED_FRAGMENT
+
+      name_markup = Regexp.last_match(1)
+      filter_markup = Regexp.last_match(2)
+      @name = Expression.parse(name_markup)
+      if filter_markup =~ FILTER_MARKUP_REGEX
+        filters = Regexp.last_match(1).scan(FILTER_PARSER)
+        filters.each do |f|
+          next unless f =~ /\w+/
+
+          filtername = Regexp.last_match(0)
+          filterargs = f.scan(FILTER_ARGS_REGEX).flatten
+          @filters << parse_filter_expressions(filtername, filterargs)
         end
       end
     end
 
     def strict_parse(markup)
-      # Very simple valid cases
-      if markup =~ EasyParse
-        @name = $1
-        @filters = []
-        return
-      end
-
       @filters = []
       p = Parser.new(markup)
-      # Could be just filters with no input
-      @name = p.look(:pipe) ? ''.freeze : p.expression
+
+      @name = Expression.parse(p.expression)
       while p.consume?(:pipe)
         filtername = p.consume(:id)
         filterargs = p.consume?(:colon) ? parse_filterargs(p) : []
-        @filters << [filtername, filterargs]
+        @filters << parse_filter_expressions(filtername, filterargs)
       end
       p.consume(:end_of_string)
-    rescue SyntaxError => e
-      e.message << " in \"{{#{markup}}}\""
-      raise e
     end
 
     def parse_filterargs(p)
       # first argument
       filterargs = [p.argument]
       # followed by comma separated others
-      while p.consume?(:comma)
-        filterargs << p.argument
-      end
+      filterargs << p.argument while p.consume?(:comma)
       filterargs
     end
 
     def render(context)
-      return ''.freeze if @name.nil?
-      @filters.inject(context[@name]) do |output, filter|
-        filterargs = []
-        keyword_args = {}
-        filter[1].to_a.each do |a|
-          if matches = a.match(/\A#{TagAttributes}\z/o)
-            keyword_args[matches[1]] = context[matches[2]]
-          else
-            filterargs << context[a]
-          end
+      obj = @filters.inject(context.evaluate(@name)) do |output, (filter_name, filter_args, filter_kwargs)|
+        filter_args = evaluate_filter_expressions(context, filter_args, filter_kwargs)
+        context.invoke(filter_name, output, *filter_args)
+      end
+
+      obj = context.apply_global_filter(obj)
+      taint_check(context, obj)
+      obj
+    end
+
+    def render_to_output_buffer(context, output)
+      obj = render(context)
+
+      if obj.is_a?(Array)
+        output << obj.join
+      elsif obj.nil?
+      else
+        output << obj.to_s
+      end
+
+      output
+    end
+
+    private
+
+    def parse_filter_expressions(filter_name, unparsed_args)
+      filter_args = []
+      keyword_args = nil
+      unparsed_args.each do |a|
+        if (matches = a.match(JUST_TAG_ATTRIBUTES))
+          keyword_args ||= {}
+          keyword_args[matches[1]] = Expression.parse(matches[2])
+        else
+          filter_args << Expression.parse(a)
         end
-        filterargs << keyword_args unless keyword_args.empty?
-        begin
-          output = context.invoke(filter[0], output, *filterargs)
-        rescue FilterNotFound
-          raise FilterNotFound, "Error - filter '#{filter[0]}' in '#{@markup.strip}' could not be found."
+      end
+      result = [filter_name, filter_args]
+      result << keyword_args if keyword_args
+      result
+    end
+
+    def evaluate_filter_expressions(context, filter_args, filter_kwargs)
+      parsed_args = filter_args.map { |expr| context.evaluate(expr) }
+      if filter_kwargs
+        parsed_kwargs = {}
+        filter_kwargs.each do |key, expr|
+          parsed_kwargs[key] = context.evaluate(expr)
         end
+        parsed_args << parsed_kwargs
+      end
+      parsed_args
+    end
+
+    def taint_check(context, obj)
+      return unless obj.tainted?
+      return if Template.taint_mode == :lax
+
+      @markup =~ QUOTED_FRAGMENT
+      name = Regexp.last_match(0)
+
+      error = TaintedError.new("variable '#{name}' is tainted and was not escaped")
+      error.line_number = line_number
+      error.template_name = context.template_name
+
+      case Template.taint_mode
+      when :warn
+        context.warnings << error
+      when :error
+        raise error
+      end
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.name] + @node.filters.flatten
       end
     end
   end

lib/liquid/variable_lookup.rb

@@ -0,0 +1,89 @@
+# frozen_string_literal: true
+
+module Liquid
+  class VariableLookup
+    SQUARE_BRACKETED = /\A\[(.*)\]\z/m.freeze
+    COMMAND_METHODS = %w[size first last].freeze
+
+    attr_reader :name, :lookups
+
+    def self.parse(markup)
+      new(markup)
+    end
+
+    def initialize(markup)
+      lookups = markup.scan(VARIABLE_PARSER)
+
+      name = lookups.shift
+      name = Expression.parse(Regexp.last_match(1)) if name =~ SQUARE_BRACKETED
+      @name = name
+
+      @lookups = lookups
+      @command_flags = 0
+
+      @lookups.each_index do |i|
+        lookup = lookups[i]
+        if lookup =~ SQUARE_BRACKETED
+          lookups[i] = Expression.parse(Regexp.last_match(1))
+        elsif COMMAND_METHODS.include?(lookup)
+          @command_flags |= 1 << i
+        end
+      end
+    end
+
+    def evaluate(context)
+      name = context.evaluate(@name)
+      object = context.find_variable(name)
+
+      @lookups.each_index do |i|
+        key = context.evaluate(@lookups[i])
+
+        # If object is a hash- or array-like object we look for the
+        # presence of the key and if its available we return it
+        if object.respond_to?(:[]) &&
+           ((object.respond_to?(:key?) && object.key?(key)) ||
+            (object.respond_to?(:fetch) && key.is_a?(Integer)))
+
+          # if its a proc we will replace the entry with the proc
+          res = context.lookup_and_evaluate(object, key)
+          object = res.to_liquid
+
+          # Some special cases. If the part wasn't in square brackets and
+          # no key with the same name was found we interpret following calls
+          # as commands and call them on the current object
+        elsif @command_flags & (1 << i) != 0 && object.respond_to?(key)
+          object = object.send(key).to_liquid
+
+          # No key was present with the desired value and it wasn't one of the directly supported
+          # keywords either. The only thing we got left is to return nil or
+          # raise an exception if `strict_variables` option is set to true
+        else
+          return nil unless context.strict_variables
+
+          raise Liquid::UndefinedVariable, "undefined variable #{key}"
+        end
+
+        # If we are dealing with a drop here we have to
+        object.context = context if object.respond_to?(:context=)
+      end
+
+      object
+    end
+
+    def ==(other)
+      self.class == other.class && state == other.state
+    end
+
+    protected
+
+    def state
+      [@name, @lookups, @command_flags]
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        @node.lookups
+      end
+    end
+  end
+end

lib/liquid/version.rb

@@ -1,4 +1,5 @@
-# encoding: utf-8
+# frozen_string_literal: true
+
 module Liquid
-  VERSION = "3.0.0.rc1"
+  VERSION = '4.0.3'
 end

liquid.gemspec

@@ -1,28 +1,31 @@
-# encoding: utf-8
-lib = File.expand_path('../lib/', __FILE__)
-$:.unshift lib unless $:.include?(lib)
+# frozen_string_literal: true
 
-require "liquid/version"
+lib = File.expand_path('lib', __dir__)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
+
+require 'liquid/version'
 
 Gem::Specification.new do |s|
-  s.name        = "liquid"
+  s.name        = 'liquid'
   s.version     = Liquid::VERSION
   s.platform    = Gem::Platform::RUBY
-  s.summary     = "A secure, non-evaling end user template engine with aesthetic markup."
-  s.authors     = ["Tobias Luetke"]
-  s.email       = ["tobi@leetsoft.com"]
-  s.homepage    = "http://www.liquidmarkup.org"
-  s.license     = "MIT"
-  #s.description = "A secure, non-evaling end user template engine with aesthetic markup."
+  s.summary     = 'A secure, non-evaling end user template engine with aesthetic markup.'
+  s.authors     = ['Tobias Lütke']
+  s.email       = ['tobi@leetsoft.com']
+  s.homepage    = 'http://www.liquidmarkup.org'
+  s.license     = 'MIT'
+  # s.description = "A secure, non-evaling end user template engine with aesthetic markup."
 
-  s.required_rubygems_version = ">= 1.3.7"
+  s.required_ruby_version     = '>= 2.4.0'
+  s.required_rubygems_version = '>= 1.3.7'
 
-  s.test_files  = Dir.glob("{test}/**/*")
-  s.files       = Dir.glob("{lib}/**/*") + %w(MIT-LICENSE README.md)
+  s.test_files  = Dir.glob('{test}/**/*')
+  s.files       = Dir.glob('{lib}/**/*') + %w[LICENSE README.md]
 
-  s.extra_rdoc_files  = ["History.md", "README.md"]
+  s.extra_rdoc_files = ['History.md', 'README.md']
 
-  s.require_path = "lib"
+  s.require_path = 'lib'
 
-  s.add_development_dependency 'rake'
+  s.add_development_dependency('minitest')
+  s.add_development_dependency('rake', '~> 11.3')
 end

performance/benchmark.rb

@@ -1,11 +1,20 @@
-require 'benchmark'
-require File.dirname(__FILE__) + '/theme_runner'
+# frozen_string_literal: true
+
+require 'benchmark/ips'
+require_relative 'theme_runner'
 
 Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
 profiler = ThemeRunner.new
 
-Benchmark.bmbm do |x|
-  x.report("parse:")   { 100.times { profiler.compile } }
-  x.report("parse & run:")   { 100.times { profiler.run } }
-end
+Benchmark.ips do |x|
+  x.time = 10
+  x.warmup = 5
 
+  puts
+  puts "Running benchmark for #{x.time} seconds (with #{x.warmup} seconds warmup)."
+  puts
+
+  x.report('parse:') { profiler.compile }
+  x.report('render:') { profiler.render }
+  x.report('parse & render:') { profiler.run }
+end

performance/memory_profile.rb

@@ -0,0 +1,26 @@
+# frozen_string_literal: true
+
+require 'benchmark/ips'
+require 'memory_profiler'
+require_relative 'theme_runner'
+
+def profile(phase, &block)
+  puts
+  puts "#{phase}:"
+  puts
+
+  report = MemoryProfiler.report(&block)
+
+  report.pretty_print(
+    color_output: true,
+    scale_bytes: true,
+    detailed_report: true
+  )
+end
+
+Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
+
+profiler = ThemeRunner.new
+
+profile('Parsing') { profiler.compile }
+profile('Rendering') { profiler.render }

performance/profile.rb

@@ -1,17 +1,26 @@
-require 'stackprof' rescue fail("install stackprof extension/gem")
-require File.dirname(__FILE__) + '/theme_runner'
+# frozen_string_literal: true
+
+require 'stackprof'
+require_relative 'theme_runner'
 
 Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
 profiler = ThemeRunner.new
 profiler.run
 
-[:cpu, :object].each do |profile_type|
-  puts "Profiling in #{profile_type.to_s} mode..."
+%i[cpu object].each do |profile_type|
+  puts "Profiling in #{profile_type} mode..."
   results = StackProf.run(mode: profile_type) do
-    100.times do
+    200.times do
       profiler.run
     end
   end
+
+  if profile_type == :cpu && (graph_filename = ENV['GRAPH_FILENAME'])
+    File.open(graph_filename, 'w') do |f|
+      StackProf::Report.new(results).print_graphviz(nil, f)
+    end
+  end
+
   StackProf::Report.new(results).print_text(false, 20)
-  File.write(ENV['FILENAME'] + "." + profile_type.to_s, Marshal.dump(results)) if ENV['FILENAME']
+  File.write(ENV['FILENAME'] + '.' + profile_type.to_s, Marshal.dump(results)) if ENV['FILENAME']
 end

performance/shopify/comment_form.rb

@@ -1,18 +1,20 @@
+# frozen_string_literal: true
+
 class CommentForm < Liquid::Block
-  Syntax = /(#{Liquid::VariableSignature}+)/
+  SYNTAX = /(#{Liquid::VARIABLE_SIGNATURE}+)/.freeze
 
   def initialize(tag_name, markup, options)
     super
 
-    if markup =~ Syntax
-      @variable_name = $1
+    if markup =~ SYNTAX
+      @variable_name = Regexp.last_match(1)
       @attributes = {}
     else
-      raise SyntaxError.new("Syntax Error in 'comment_form' - Valid syntax: comment_form [article]")
+      raise SyntaxError, "Syntax Error in 'comment_form' - Valid syntax: comment_form [article]"
     end
   end
 
-  def render(context)
+  def render_to_output_buffer(context, output)
     article = context[@variable_name]
 
     context.stack do
@@ -20,14 +22,16 @@ class CommentForm < Liquid::Block
         'posted_successfully?' => context.registers[:posted_successfully],
         'errors' => context['comment.errors'],
         'author' => context['comment.author'],
-        'email'  => context['comment.email'],
-        'body'   => context['comment.body']
+        'email' => context['comment.email'],
+        'body' => context['comment.body'],
       }
-      wrap_in_form(article, render_all(@nodelist, context))
+
+      output << wrap_in_form(article, render_all(@nodelist, context, output))
+      output
     end
   end
 
   def wrap_in_form(article, input)
-    %Q{<form id="article-#{article.id}-comment-form" class="comment-form" method="post" action="">\n#{input}\n</form>}
+    %(<form id="article-#{article.id}-comment-form" class="comment-form" method="post" action="">\n#{input}\n</form>)
   end
 end

performance/shopify/database.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'yaml'
 
 module Database
@@ -5,7 +7,7 @@ module Database
   # to liquid as assigns. All this is based on Shopify
   def self.tables
     @tables ||= begin
-      db = YAML.load_file(File.dirname(__FILE__) + '/vision.database.yml')
+      db = YAML.load_file("#{__dir__}/vision.database.yml")
 
       # From vision source
       db['products'].each do |product|
@@ -16,8 +18,11 @@ module Database
       end
 
       # key the tables by handles, as this is how liquid expects it.
-      db = db.inject({}) do |assigns, (key, values)|
-        assigns[key] = values.inject({}) { |h, v| h[v['handle']] = v; h; }
+      db = db.each_with_object({}) do |(key, values), assigns|
+        assigns[key] = values.each_with_object({}) do |v, h|
+          h[v['handle']] = v
+          h
+        end
         assigns
       end
 
@@ -29,9 +34,9 @@ module Database
       db['article']    = db['blog']['articles'].first
 
       db['cart']       = {
-        'total_price' => db['line_items'].values.inject(0) { |sum, item| sum += item['line_price'] * item['quantity'] },
-        'item_count'  => db['line_items'].values.inject(0) { |sum, item| sum += item['quantity'] },
-        'items'       => db['line_items'].values
+        'total_price' => db['line_items'].values.inject(0) { |sum, item| sum + item['line_price'] * item['quantity'] },
+        'item_count' => db['line_items'].values.inject(0) { |sum, item| sum + item['quantity'] },
+        'items' => db['line_items'].values,
       }
 
       db
@@ -39,7 +44,7 @@ module Database
   end
 end
 
-if __FILE__ == $0
-  p Database.tables['collections']['frontpage'].keys
-  #p Database.tables['blog']['articles']
+if __FILE__ == $PROGRAM_NAME
+  p(Database.tables['collections']['frontpage'].keys)
+  # p Database.tables['blog']['articles']
 end

performance/shopify/json_filter.rb

@@ -1,9 +1,9 @@
+# frozen_string_literal: true
+
 require 'json'
 
 module JsonFilter
-
   def json(object)
-    JSON.dump(object.reject {|k,v| k == "collections" })
+    JSON.dump(object.reject { |k, _v| k == 'collections' })
   end
-
 end

performance/shopify/liquid.rb

@@ -1,19 +1,21 @@
-$:.unshift File.dirname(__FILE__) + '/../../lib'
-require File.dirname(__FILE__) + '/../../lib/liquid'
+# frozen_string_literal: true
 
-require File.dirname(__FILE__) + '/comment_form'
-require File.dirname(__FILE__) + '/paginate'
-require File.dirname(__FILE__) + '/json_filter'
-require File.dirname(__FILE__) + '/money_filter'
-require File.dirname(__FILE__) + '/shop_filter'
-require File.dirname(__FILE__) + '/tag_filter'
-require File.dirname(__FILE__) + '/weight_filter'
+$LOAD_PATH.unshift(__dir__ + '/../../lib')
+require_relative '../../lib/liquid'
 
-Liquid::Template.register_tag 'paginate', Paginate
-Liquid::Template.register_tag 'form', CommentForm
+require_relative 'comment_form'
+require_relative 'paginate'
+require_relative 'json_filter'
+require_relative 'money_filter'
+require_relative 'shop_filter'
+require_relative 'tag_filter'
+require_relative 'weight_filter'
 
-Liquid::Template.register_filter JsonFilter
-Liquid::Template.register_filter MoneyFilter
-Liquid::Template.register_filter WeightFilter
-Liquid::Template.register_filter ShopFilter
-Liquid::Template.register_filter TagFilter
+Liquid::Template.register_tag('paginate', Paginate)
+Liquid::Template.register_tag('form', CommentForm)
+
+Liquid::Template.register_filter(JsonFilter)
+Liquid::Template.register_filter(MoneyFilter)
+Liquid::Template.register_filter(WeightFilter)
+Liquid::Template.register_filter(ShopFilter)
+Liquid::Template.register_filter(TagFilter)

performance/shopify/money_filter.rb

@@ -1,13 +1,16 @@
-module MoneyFilter
+# frozen_string_literal: true
 
+module MoneyFilter
   def money_with_currency(money)
     return '' if money.nil?
-    sprintf("$ %.2f USD", money/100.0)
+
+    format('$ %.2f USD', money / 100.0)
   end
 
   def money(money)
     return '' if money.nil?
-    sprintf("$ %.2f", money/100.0)
+
+    format('$ %.2f', money / 100.0)
   end
 
   private

performance/shopify/paginate.rb

@@ -1,67 +1,67 @@
+# frozen_string_literal: true
+
 class Paginate < Liquid::Block
-  Syntax     = /(#{Liquid::QuotedFragment})\s*(by\s*(\d+))?/
+  SYNTAX = /(#{Liquid::QUOTED_FRAGMENT})\s*(by\s*(\d+))?/.freeze
 
   def initialize(tag_name, markup, options)
     super
 
-    @nodelist = []
-
-    if markup =~ Syntax
-      @collection_name = $1
-      @page_size = if $2
-        $3.to_i
+    if markup =~ SYNTAX
+      @collection_name = Regexp.last_match(1)
+      @page_size = if Regexp.last_match(2)
+        Regexp.last_match(3).to_i
       else
         20
       end
 
       @attributes = { 'window_size' => 3 }
-      markup.scan(Liquid::TagAttributes) do |key, value|
+      markup.scan(Liquid::TAG_ATTRIBUTES) do |key, value|
         @attributes[key] = value
       end
     else
-      raise SyntaxError.new("Syntax Error in tag 'paginate' - Valid syntax: paginate [collection] by number")
+      raise SyntaxError, "Syntax Error in tag 'paginate' - Valid syntax: paginate [collection] by number"
     end
   end
 
-  def render(context)
+  def render_to_output_buffer(context, output)
     @context = context
 
     context.stack do
-      current_page  = context['current_page'].to_i
+      current_page = context['current_page'].to_i
 
       pagination = {
-        'page_size'      => @page_size,
-        'current_page'   => 5,
-        'current_offset' => @page_size * 5
+        'page_size' => @page_size,
+        'current_page' => 5,
+        'current_offset' => @page_size * 5,
       }
 
       context['paginate'] = pagination
 
-      collection_size  = context[@collection_name].size
+      collection_size = context[@collection_name].size
 
-      raise ArgumentError.new("Cannot paginate array '#{@collection_name}'. Not found.") if collection_size.nil?
+      raise ArgumentError, "Cannot paginate array '#{@collection_name}'. Not found." if collection_size.nil?
 
       page_count = (collection_size.to_f / @page_size.to_f).to_f.ceil + 1
 
       pagination['items']      = collection_size
-      pagination['pages']      = page_count -1
-      pagination['previous']   = link('&laquo; Previous', current_page-1 )  unless 1 >= current_page
-      pagination['next']       = link('Next &raquo;', current_page+1 )      unless page_count <= current_page+1
+      pagination['pages']      = page_count - 1
+      pagination['previous']   = link('&laquo; Previous', current_page - 1)  unless current_page <= 1
+      pagination['next']       = link('Next &raquo;', current_page + 1)      unless page_count <= current_page + 1
       pagination['parts']      = []
 
       hellip_break = false
 
       if page_count > 2
-        1.upto(page_count-1) do |page|
-
+        1.upto(page_count - 1) do |page|
           if current_page == page
             pagination['parts'] << no_link(page)
           elsif page == 1
             pagination['parts'] << link(page, page)
-          elsif page == page_count -1
+          elsif page == page_count - 1
             pagination['parts'] << link(page, page)
-          elsif page <= current_page - @attributes['window_size'] or page >= current_page + @attributes['window_size']
+          elsif page <= current_page - @attributes['window_size'] || page >= current_page + @attributes['window_size']
             next if hellip_break
+
             pagination['parts'] << no_link('&hellip;')
             hellip_break = true
             next
@@ -73,21 +73,21 @@ class Paginate < Liquid::Block
         end
       end
 
-      render_all(@nodelist, context)
+      super
     end
   end
 
   private
 
   def no_link(title)
-    { 'title' => title, 'is_link' => false}
+    { 'title' => title, 'is_link' => false }
   end
 
   def link(title, page)
-    { 'title' => title, 'url' => current_url + "?page=#{page}", 'is_link' => true}
+    { 'title' => title, 'url' => current_url + "?page=#{page}", 'is_link' => true }
   end
 
   def current_url
-    "/collections/frontpage"
+    '/collections/frontpage'
   end
 end

performance/shopify/shop_filter.rb

@@ -1,5 +1,6 @@
-module ShopFilter
+# frozen_string_literal: true
 
+module ShopFilter
   def asset_url(input)
     "/files/1/[shop_id]/[shop_id]/assets/#{input}"
   end
@@ -16,16 +17,16 @@ module ShopFilter
     %(<script src="#{url}" type="text/javascript"></script>)
   end
 
-  def stylesheet_tag(url, media="all")
+  def stylesheet_tag(url, media = 'all')
     %(<link href="#{url}" rel="stylesheet" type="text/css"  media="#{media}"  />)
   end
 
-  def link_to(link, url, title="")
-    %|<a href="#{url}" title="#{title}">#{link}</a>|
+  def link_to(link, url, title = '')
+    %(<a href="#{url}" title="#{title}">#{link}</a>)
   end
 
-  def img_tag(url, alt="")
-    %|<img src="#{url}" alt="#{alt}" />|
+  def img_tag(url, alt = '')
+    %(<img src="#{url}" alt="#{alt}" />)
   end
 
   def link_to_vendor(vendor)
@@ -53,36 +54,30 @@ module ShopFilter
   end
 
   def product_img_url(url, style = 'small')
-
-    unless url =~ /\Aproducts\/([\w\-\_]+)\.(\w{2,4})/
-      raise ArgumentError, 'filter "size" can only be called on product images'
-    end
+    raise ArgumentError, 'filter "size" can only be called on product images' unless url =~ %r{\Aproducts/([\w\-\_]+)\.(\w{2,4})}
 
     case style
     when 'original'
       return '/files/shops/random_number/' + url
     when 'grande', 'large', 'medium', 'compact', 'small', 'thumb', 'icon'
-      "/files/shops/random_number/products/#{$1}_#{style}.#{$2}"
+      "/files/shops/random_number/products/#{Regexp.last_match(1)}_#{style}.#{Regexp.last_match(2)}"
     else
       raise ArgumentError, 'valid parameters for filter "size" are: original, grande, large, medium, compact, small, thumb and icon '
     end
   end
 
   def default_pagination(paginate)
-
     html = []
     html << %(<span class="prev">#{link_to(paginate['previous']['title'], paginate['previous']['url'])}</span>) if paginate['previous']
 
-    for part in paginate['parts']
-
-      if part['is_link']
-        html << %(<span class="page">#{link_to(part['title'], part['url'])}</span>)
+    paginate['parts'].each do |part|
+      html << if part['is_link']
+        %(<span class="page">#{link_to(part['title'], part['url'])}</span>)
       elsif part['title'].to_i == paginate['current_page'].to_i
-        html << %(<span class="page current">#{part['title']}</span>)
+        %(<span class="page current">#{part['title']}</span>)
       else
-        html << %(<span class="deco">#{part['title']}</span>)
+        %(<span class="deco">#{part['title']}</span>)
       end
-
     end
 
     html << %(<span class="next">#{link_to(paginate['next']['title'], paginate['next']['url'])}</span>) if paginate['next']
@@ -106,5 +101,4 @@ module ShopFilter
     result.gsub!(/\A-+/, '') if result[0] == '-'
     result
   end
-
 end

performance/shopify/tag_filter.rb

@@ -1,10 +1,11 @@
-module TagFilter
+# frozen_string_literal: true
 
+module TagFilter
   def link_to_tag(label, tag)
     "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tag}\">#{label}</a>"
   end
 
-  def highlight_active_tag(tag, css_class='active')
+  def highlight_active_tag(tag, css_class = 'active')
     if @context['current_tags'].include?(tag)
       "<span class=\"#{css_class}\">#{tag}</span>"
     else
@@ -14,12 +15,11 @@ module TagFilter
 
   def link_to_add_tag(label, tag)
     tags = (@context['current_tags'] + [tag]).uniq
-    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join("+")}\">#{label}</a>"
+    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join('+')}\">#{label}</a>"
   end
 
   def link_to_remove_tag(label, tag)
     tags = (@context['current_tags'] - [tag]).uniq
-    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join("+")}\">#{label}</a>"
+    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join('+')}\">#{label}</a>"
   end
-
 end

performance/shopify/weight_filter.rb

@@ -1,11 +1,11 @@
-module WeightFilter
+# frozen_string_literal: true
 
+module WeightFilter
   def weight(grams)
-    sprintf("%.2f", grams / 1000)
+    format('%.2f', grams / 1000)
   end
 
   def weight_with_unit(grams)
     "#{weight(grams)} kg"
   end
-
 end

performance/theme_runner.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This profiler run simulates Shopify.
 # We are looking in the tests directory for liquid files and render them within the designated layout file.
 # We will also export a substantial database to liquid which the templates can render values of.
@@ -6,73 +8,115 @@
 # Shopify which is likely the biggest user of liquid in the world which something to the tune of several
 # million Template#render calls a day.
 
-require File.dirname(__FILE__) + '/shopify/liquid'
-require File.dirname(__FILE__) + '/shopify/database.rb'
+require_relative 'shopify/liquid'
+require_relative 'shopify/database'
 
 class ThemeRunner
   class FileSystem
-
     def initialize(path)
       @path = path
     end
 
     # Called by Liquid to retrieve a template file
-    def read_template_file(template_path, context)
+    def read_template_file(template_path)
       File.read(@path + '/' + template_path + '.liquid')
     end
   end
 
-  # Load all templates into memory, do this now so that
-  # we don't profile IO.
+  # Initialize a new liquid ThemeRunner instance
+  # Will load all templates into memory, do this now so that we don't profile IO.
   def initialize
-    @tests = Dir[File.dirname(__FILE__) + '/tests/**/*.liquid'].collect do |test|
+    @tests = Dir[__dir__ + '/tests/**/*.liquid'].collect do |test|
       next if File.basename(test) == 'theme.liquid'
 
       theme_path = File.dirname(test) + '/theme.liquid'
-
-      [File.read(test), (File.file?(theme_path) ? File.read(theme_path) : nil), test]
+      {
+        liquid: File.read(test),
+        layout: (File.file?(theme_path) ? File.read(theme_path) : nil),
+        template_name: test,
+      }
     end.compact
+
+    compile_all_tests
   end
 
+  # `compile` will test just the compilation portion of liquid without any templates
   def compile
-    # Dup assigns because will make some changes to them
-
-    @tests.each do |liquid, layout, template_name|
-
-      tmpl = Liquid::Template.new
-      tmpl.parse(liquid)
-      tmpl = Liquid::Template.new
-      tmpl.parse(layout)
+    @tests.each do |test_hash|
+      Liquid::Template.new.parse(test_hash[:liquid])
+      Liquid::Template.new.parse(test_hash[:layout])
     end
   end
 
-   def run
+  # `run` is called to benchmark rendering and compiling at the same time
+  def run
+    each_test do |liquid, layout, assigns, page_template, template_name|
+      compile_and_render(liquid, layout, assigns, page_template, template_name)
+    end
+  end
+
+  # `render` is called to benchmark just the render portion of liquid
+  def render
+    @compiled_tests.each do |test|
+      tmpl = test[:tmpl]
+      assigns = test[:assigns]
+      layout = test[:layout]
+
+      if layout
+        assigns['content_for_layout'] = tmpl.render!(assigns)
+        layout.render!(assigns)
+      else
+        tmpl.render!(assigns)
+      end
+    end
+  end
+
+  private
+
+  def compile_and_render(template, layout, assigns, page_template, template_file)
+    compiled_test = compile_test(template, layout, assigns, page_template, template_file)
+    assigns['content_for_layout'] = compiled_test[:tmpl].render!(assigns)
+    compiled_test[:layout].render!(assigns) if layout
+  end
+
+  def compile_all_tests
+    @compiled_tests = []
+    each_test do |liquid, layout, assigns, page_template, template_name|
+      @compiled_tests << compile_test(liquid, layout, assigns, page_template, template_name)
+    end
+    @compiled_tests
+  end
+
+  def compile_test(template, layout, assigns, page_template, template_file)
+    tmpl = init_template(page_template, template_file)
+    parsed_template = tmpl.parse(template).dup
+
+    if layout
+      parsed_layout = tmpl.parse(layout)
+      { tmpl: parsed_template, assigns: assigns, layout: parsed_layout }
+    else
+      { tmpl: parsed_template, assigns: assigns }
+    end
+  end
+
+  # utility method with similar functionality needed in `compile_all_tests` and `run`
+  def each_test
     # Dup assigns because will make some changes to them
     assigns = Database.tables.dup
 
-    @tests.each do |liquid, layout, template_name|
-
-      # Compute page_tempalte outside of profiler run, uninteresting to profiler
-      page_template = File.basename(template_name, File.extname(template_name))
-      compile_and_render(liquid, layout, assigns, page_template, template_name)
-
+    @tests.each do |test_hash|
+      # Compute page_template outside of profiler run, uninteresting to profiler
+      page_template = File.basename(test_hash[:template_name], File.extname(test_hash[:template_name]))
+      yield(test_hash[:liquid], test_hash[:layout], assigns, page_template, test_hash[:template_name])
     end
   end
 
-
-  def compile_and_render(template, layout, assigns, page_template, template_file)
+  # set up a new Liquid::Template object for use in `compile_and_render` and `compile_test`
+  def init_template(page_template, template_file)
     tmpl = Liquid::Template.new
     tmpl.assigns['page_title'] = 'Page title'
     tmpl.assigns['template'] = page_template
     tmpl.registers[:file_system] = ThemeRunner::FileSystem.new(File.dirname(template_file))
-
-    content_for_layout = tmpl.parse(template).render!(assigns)
-
-    if layout
-      assigns['content_for_layout'] = content_for_layout
-      tmpl.parse(layout).render!(assigns)
-    else
-      content_for_layout
-    end
+    tmpl
   end
 end

test/integration/assign_test.rb

@@ -1,27 +1,50 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-class AssignTest < Test::Unit::TestCase
+class AssignTest < Minitest::Test
   include Liquid
 
+  def test_assign_with_hyphen_in_variable_name
+    template_source = <<-END_TEMPLATE
+    {% assign this-thing = 'Print this-thing' %}
+    {{ this-thing }}
+    END_TEMPLATE
+    template = Template.parse(template_source)
+    rendered = template.render!
+    assert_equal 'Print this-thing', rendered.strip
+  end
+
   def test_assigned_variable
     assert_template_result('.foo.',
                            '{% assign foo = values %}.{{ foo[0] }}.',
-                           'values' => %w{foo bar baz})
+                           'values' => %w[foo bar baz])
 
     assert_template_result('.bar.',
                            '{% assign foo = values %}.{{ foo[1] }}.',
-                           'values' => %w{foo bar baz})
+                           'values' => %w[foo bar baz])
   end
 
   def test_assign_with_filter
     assert_template_result('.bar.',
                            '{% assign foo = values | split: "," %}.{{ foo[1] }}.',
-                           'values' => "foo,bar,baz")
+                           'values' => 'foo,bar,baz')
   end
 
   def test_assign_syntax_error
     assert_match_syntax_error(/assign/,
-                       '{% assign foo not values %}.',
-                       'values' => "foo,bar,baz")
+                              '{% assign foo not values %}.',
+                              'values' => 'foo,bar,baz')
+  end
+
+  def test_assign_uses_error_mode
+    with_error_mode(:strict) do
+      assert_raises(SyntaxError) do
+        Template.parse("{% assign foo = ('X' | downcase) %}")
+      end
+    end
+    with_error_mode(:lax) do
+      assert Template.parse("{% assign foo = ('X' | downcase) %}")
+    end
   end
 end # AssignTest

test/integration/blank_test.rb

@@ -1,20 +1,21 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class FoobarTag < Liquid::Tag
-  def render(*args)
-    " "
+  def render_to_output_buffer(_context, output)
+    output << ' '
+    output
   end
-
-  Liquid::Template.register_tag('foobar', FoobarTag)
 end
 
 class BlankTestFileSystem
-  def read_template_file(template_path, context)
+  def read_template_file(template_path)
     template_path
   end
 end
 
-class BlankTest < Test::Unit::TestCase
+class BlankTest < Minitest::Test
   include Liquid
   N = 10
 
@@ -31,76 +32,78 @@ class BlankTest < Test::Unit::TestCase
   end
 
   def test_new_tags_are_not_blank_by_default
-    assert_template_result(" "*N, wrap_in_for("{% foobar %}"))
+    with_custom_tag('foobar', FoobarTag) do
+      assert_template_result(' ' * N, wrap_in_for('{% foobar %}'))
+    end
   end
 
   def test_loops_are_blank
-    assert_template_result("", wrap_in_for(" "))
+    assert_template_result('', wrap_in_for(' '))
   end
 
   def test_if_else_are_blank
-    assert_template_result("", "{% if true %} {% elsif false %} {% else %} {% endif %}")
+    assert_template_result('', '{% if true %} {% elsif false %} {% else %} {% endif %}')
   end
 
   def test_unless_is_blank
-    assert_template_result("", wrap("{% unless true %} {% endunless %}"))
+    assert_template_result('', wrap('{% unless true %} {% endunless %}'))
   end
 
   def test_mark_as_blank_only_during_parsing
-    assert_template_result(" "*(N+1), wrap(" {% if false %} this never happens, but still, this block is not blank {% endif %}"))
+    assert_template_result(' ' * (N + 1), wrap(' {% if false %} this never happens, but still, this block is not blank {% endif %}'))
   end
 
   def test_comments_are_blank
-    assert_template_result("", wrap(" {% comment %} whatever {% endcomment %} "))
+    assert_template_result('', wrap(' {% comment %} whatever {% endcomment %} '))
   end
 
   def test_captures_are_blank
-    assert_template_result("", wrap(" {% capture foo %} whatever {% endcapture %} "))
+    assert_template_result('', wrap(' {% capture foo %} whatever {% endcapture %} '))
   end
 
   def test_nested_blocks_are_blank_but_only_if_all_children_are
-    assert_template_result("", wrap(wrap(" ")))
-    assert_template_result("\n       but this is not "*(N+1),
-      wrap(%q{{% if true %} {% comment %} this is blank {% endcomment %} {% endif %}
-      {% if true %} but this is not {% endif %}}))
+    assert_template_result('', wrap(wrap(' ')))
+    assert_template_result("\n       but this is not " * (N + 1),
+                           wrap('{% if true %} {% comment %} this is blank {% endcomment %} {% endif %}
+      {% if true %} but this is not {% endif %}'))
   end
 
   def test_assigns_are_blank
-    assert_template_result("", wrap(' {% assign foo = "bar" %} '))
+    assert_template_result('', wrap(' {% assign foo = "bar" %} '))
   end
 
   def test_whitespace_is_blank
-    assert_template_result("", wrap(" "))
-    assert_template_result("", wrap("\t"))
+    assert_template_result('', wrap(' '))
+    assert_template_result('', wrap("\t"))
   end
 
   def test_whitespace_is_not_blank_if_other_stuff_is_present
-    body = "     x "
-    assert_template_result(body*(N+1), wrap(body))
+    body = '     x '
+    assert_template_result(body * (N + 1), wrap(body))
   end
 
   def test_increment_is_not_blank
-    assert_template_result(" 0"*2*(N+1), wrap("{% assign foo = 0 %} {% increment foo %} {% decrement foo %}"))
+    assert_template_result(' 0' * 2 * (N + 1), wrap('{% assign foo = 0 %} {% increment foo %} {% decrement foo %}'))
   end
 
   def test_cycle_is_not_blank
-    assert_template_result("  "*((N+1)/2)+" ", wrap("{% cycle ' ', ' ' %}"))
+    assert_template_result('  ' * ((N + 1) / 2) + ' ', wrap("{% cycle ' ', ' ' %}"))
   end
 
   def test_raw_is_not_blank
-    assert_template_result("  "*(N+1), wrap(" {% raw %} {% endraw %}"))
+    assert_template_result('  ' * (N + 1), wrap(' {% raw %} {% endraw %}'))
   end
 
   def test_include_is_blank
     Liquid::Template.file_system = BlankTestFileSystem.new
-    assert_template_result "foobar"*(N+1), wrap("{% include 'foobar' %}")
-    assert_template_result " foobar "*(N+1), wrap("{% include ' foobar ' %}")
-    assert_template_result "   "*(N+1), wrap(" {% include ' ' %} ")
+    assert_template_result 'foobar' * (N + 1), wrap("{% include 'foobar' %}")
+    assert_template_result ' foobar ' * (N + 1), wrap("{% include ' foobar ' %}")
+    assert_template_result '   ' * (N + 1), wrap(" {% include ' ' %} ")
   end
 
   def test_case_is_blank
-    assert_template_result("", wrap(" {% assign foo = 'bar' %} {% case foo %} {% when 'bar' %} {% when 'whatever' %} {% else %} {% endcase %} "))
-    assert_template_result("", wrap(" {% assign foo = 'else' %} {% case foo %} {% when 'bar' %} {% when 'whatever' %} {% else %} {% endcase %} "))
-    assert_template_result("   x  "*(N+1), wrap(" {% assign foo = 'else' %} {% case foo %} {% when 'bar' %} {% when 'whatever' %} {% else %} x {% endcase %} "))
+    assert_template_result('', wrap(" {% assign foo = 'bar' %} {% case foo %} {% when 'bar' %} {% when 'whatever' %} {% else %} {% endcase %} "))
+    assert_template_result('', wrap(" {% assign foo = 'else' %} {% case foo %} {% when 'bar' %} {% when 'whatever' %} {% else %} {% endcase %} "))
+    assert_template_result('   x  ' * (N + 1), wrap(" {% assign foo = 'else' %} {% case foo %} {% when 'bar' %} {% when 'whatever' %} {% else %} x {% endcase %} "))
   end
 end

test/integration/block_test.rb

@@ -0,0 +1,14 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class BlockTest < Minitest::Test
+  include Liquid
+
+  def test_unexpected_end_tag
+    exc = assert_raises(SyntaxError) do
+      Template.parse('{% if true %}{% endunless %}')
+    end
+    assert_equal exc.message, "Liquid syntax error: 'endunless' is not a valid delimiter for if tags. use endif"
+  end
+end

test/integration/capture_test.rb

@@ -1,10 +1,22 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-class CaptureTest < Test::Unit::TestCase
+class CaptureTest < Minitest::Test
   include Liquid
 
   def test_captures_block_content_in_variable
-    assert_template_result("test string", "{% capture 'var' %}test string{% endcapture %}{{var}}", {})
+    assert_template_result('test string', "{% capture 'var' %}test string{% endcapture %}{{var}}", {})
+  end
+
+  def test_capture_with_hyphen_in_variable_name
+    template_source = <<-END_TEMPLATE
+    {% capture this-thing %}Print this-thing{% endcapture %}
+    {{ this-thing }}
+    END_TEMPLATE
+    template = Template.parse(template_source)
+    rendered = template.render!
+    assert_equal 'Print this-thing', rendered.strip
   end
 
   def test_capture_to_variable_from_outer_scope_if_existing
@@ -20,7 +32,7 @@ class CaptureTest < Test::Unit::TestCase
     END_TEMPLATE
     template = Template.parse(template_source)
     rendered = template.render!
-    assert_equal "test-string", rendered.gsub(/\s/, '')
+    assert_equal 'test-string', rendered.gsub(/\s/, '')
   end
 
   def test_assigning_from_capture
@@ -35,6 +47,6 @@ class CaptureTest < Test::Unit::TestCase
     END_TEMPLATE
     template = Template.parse(template_source)
     rendered = template.render!
-    assert_equal "3-3", rendered.gsub(/\s/, '')
+    assert_equal '3-3', rendered.gsub(/\s/, '')
   end
 end # CaptureTest

test/integration/context_test.rb

@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-class ContextTest < Test::Unit::TestCase
+class ContextTest < Minitest::Test
   include Liquid
 
   def test_override_global_filter
@@ -16,18 +18,17 @@ class ContextTest < Test::Unit::TestCase
       end
     end
 
-    Template.register_filter(global)
-    assert_equal 'Global test', Template.parse("{{'test' | notice }}").render!
-    assert_equal 'Local test', Template.parse("{{'test' | notice }}").render!({}, :filters => [local])
+    with_global_filter(global) do
+      assert_equal 'Global test', Template.parse("{{'test' | notice }}").render!
+      assert_equal 'Local test', Template.parse("{{'test' | notice }}").render!({}, filters: [local])
+    end
   end
 
   def test_has_key_will_not_add_an_error_for_missing_keys
-    Template.error_mode = :strict
-
-    context = Context.new
-
-    context.has_key?('unknown')
-
-    assert_empty context.errors
+    with_error_mode :strict do
+      context = Context.new
+      context.key?('unknown')
+      assert_empty context.errors
+    end
   end
 end

test/integration/document_test.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class DocumentTest < Minitest::Test
+  include Liquid
+
+  def test_unexpected_outer_tag
+    exc = assert_raises(SyntaxError) do
+      Template.parse('{% else %}')
+    end
+    assert_equal exc.message, "Liquid syntax error: Unexpected outer 'else' tag"
+  end
+
+  def test_unknown_tag
+    exc = assert_raises(SyntaxError) do
+      Template.parse('{% foo %}')
+    end
+    assert_equal exc.message, "Liquid syntax error: Unknown tag 'foo'"
+  end
+end

test/integration/drop_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ContextDrop < Liquid::Drop
@@ -13,16 +15,15 @@ class ContextDrop < Liquid::Drop
     @context['forloop.index']
   end
 
-  def before_method(method)
-    return @context[method]
+  def liquid_method_missing(method)
+    @context[method]
   end
 end
 
 class ProductDrop < Liquid::Drop
-
   class TextDrop < Liquid::Drop
     def array
-      ['text1', 'text2']
+      %w[text1 text2]
     end
 
     def text
@@ -31,8 +32,8 @@ class ProductDrop < Liquid::Drop
   end
 
   class CatchallDrop < Liquid::Drop
-    def before_method(method)
-      return 'method: ' << method.to_s
+    def liquid_method_missing(method)
+      +'catchall_method: ' << method.to_s
     end
   end
 
@@ -48,14 +49,19 @@ class ProductDrop < Liquid::Drop
     ContextDrop.new
   end
 
+  def user_input
+    (+'foo').taint
+  end
+
   protected
-    def callmenot
-      "protected"
-    end
+
+  def callmenot
+    'protected'
+  end
 end
 
 class EnumerableDrop < Liquid::Drop
-  def before_method(method)
+  def liquid_method_missing(method)
     method
   end
 
@@ -89,7 +95,7 @@ end
 class RealEnumerableDrop < Liquid::Drop
   include Enumerable
 
-  def before_method(method)
+  def liquid_method_missing(method)
     method
   end
 
@@ -100,111 +106,135 @@ class RealEnumerableDrop < Liquid::Drop
   end
 end
 
-class DropsTest < Test::Unit::TestCase
+class DropsTest < Minitest::Test
   include Liquid
 
   def test_product_drop
-    assert_nothing_raised do
-      tpl = Liquid::Template.parse( '  '  )
+    tpl = Liquid::Template.parse('  ')
+    assert_equal '  ', tpl.render!('product' => ProductDrop.new)
+  end
+
+  def test_rendering_raises_on_tainted_attr
+    with_taint_mode(:error) do
+      tpl = Liquid::Template.parse('{{ product.user_input }}')
+      assert_raises TaintedError do
+        tpl.render!('product' => ProductDrop.new)
+      end
+    end
+  end
+
+  def test_rendering_warns_on_tainted_attr
+    with_taint_mode(:warn) do
+      tpl = Liquid::Template.parse('{{ product.user_input }}')
+      context = Context.new('product' => ProductDrop.new)
+      tpl.render!(context)
+      assert_equal [Liquid::TaintedError], context.warnings.map(&:class)
+      assert_equal "variable 'product.user_input' is tainted and was not escaped", context.warnings.first.to_s(false)
+    end
+  end
+
+  def test_rendering_doesnt_raise_on_escaped_tainted_attr
+    with_taint_mode(:error) do
+      tpl = Liquid::Template.parse('{{ product.user_input | escape }}')
       tpl.render!('product' => ProductDrop.new)
     end
   end
 
   def test_drop_does_only_respond_to_whitelisted_methods
-    assert_equal "", Liquid::Template.parse("{{ product.inspect }}").render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse("{{ product.pretty_inspect }}").render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse("{{ product.whatever }}").render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse('{{ product | map: "inspect" }}').render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse('{{ product | map: "pretty_inspect" }}').render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse('{{ product | map: "whatever" }}').render!('product' => ProductDrop.new)
+    assert_equal '', Liquid::Template.parse('{{ product.inspect }}').render!('product' => ProductDrop.new)
+    assert_equal '', Liquid::Template.parse('{{ product.pretty_inspect }}').render!('product' => ProductDrop.new)
+    assert_equal '', Liquid::Template.parse('{{ product.whatever }}').render!('product' => ProductDrop.new)
+    assert_equal '', Liquid::Template.parse('{{ product | map: "inspect" }}').render!('product' => ProductDrop.new)
+    assert_equal '', Liquid::Template.parse('{{ product | map: "pretty_inspect" }}').render!('product' => ProductDrop.new)
+    assert_equal '', Liquid::Template.parse('{{ product | map: "whatever" }}').render!('product' => ProductDrop.new)
   end
 
   def test_drops_respond_to_to_liquid
-    assert_equal "text1", Liquid::Template.parse("{{ product.to_liquid.texts.text }}").render!('product' => ProductDrop.new)
-    assert_equal "text1", Liquid::Template.parse('{{ product | map: "to_liquid" | map: "texts" | map: "text" }}').render!('product' => ProductDrop.new)
+    assert_equal 'text1', Liquid::Template.parse('{{ product.to_liquid.texts.text }}').render!('product' => ProductDrop.new)
+    assert_equal 'text1', Liquid::Template.parse('{{ product | map: "to_liquid" | map: "texts" | map: "text" }}').render!('product' => ProductDrop.new)
   end
 
   def test_text_drop
-    output = Liquid::Template.parse( ' {{ product.texts.text }} '  ).render!('product' => ProductDrop.new)
+    output = Liquid::Template.parse(' {{ product.texts.text }} ').render!('product' => ProductDrop.new)
     assert_equal ' text1 ', output
   end
 
-  def test_unknown_method
-    output = Liquid::Template.parse( ' {{ product.catchall.unknown }} '  ).render!('product' => ProductDrop.new)
-    assert_equal ' method: unknown ', output
+  def test_catchall_unknown_method
+    output = Liquid::Template.parse(' {{ product.catchall.unknown }} ').render!('product' => ProductDrop.new)
+    assert_equal ' catchall_method: unknown ', output
   end
 
-  def test_integer_argument_drop
-    output = Liquid::Template.parse( ' {{ product.catchall[8] }} '  ).render!('product' => ProductDrop.new)
-    assert_equal ' method: 8 ', output
+  def test_catchall_integer_argument_drop
+    output = Liquid::Template.parse(' {{ product.catchall[8] }} ').render!('product' => ProductDrop.new)
+    assert_equal ' catchall_method: 8 ', output
   end
 
   def test_text_array_drop
-    output = Liquid::Template.parse( '{% for text in product.texts.array %} {{text}} {% endfor %}'  ).render!('product' => ProductDrop.new)
+    output = Liquid::Template.parse('{% for text in product.texts.array %} {{text}} {% endfor %}').render!('product' => ProductDrop.new)
     assert_equal ' text1  text2 ', output
   end
 
   def test_context_drop
-    output = Liquid::Template.parse( ' {{ context.bar }} '  ).render!('context' => ContextDrop.new, 'bar' => "carrot")
+    output = Liquid::Template.parse(' {{ context.bar }} ').render!('context' => ContextDrop.new, 'bar' => 'carrot')
     assert_equal ' carrot ', output
   end
 
   def test_nested_context_drop
-    output = Liquid::Template.parse( ' {{ product.context.foo }} '  ).render!('product' => ProductDrop.new, 'foo' => "monkey")
+    output = Liquid::Template.parse(' {{ product.context.foo }} ').render!('product' => ProductDrop.new, 'foo' => 'monkey')
     assert_equal ' monkey ', output
   end
 
   def test_protected
-    output = Liquid::Template.parse( ' {{ product.callmenot }} '  ).render!('product' => ProductDrop.new)
+    output = Liquid::Template.parse(' {{ product.callmenot }} ').render!('product' => ProductDrop.new)
     assert_equal '  ', output
   end
 
   def test_object_methods_not_allowed
-    [:dup, :clone, :singleton_class, :eval, :class_eval, :inspect].each do |method|
+    %i[dup clone singleton_class eval class_eval inspect].each do |method|
       output = Liquid::Template.parse(" {{ product.#{method} }} ").render!('product' => ProductDrop.new)
       assert_equal '  ', output
     end
   end
 
   def test_scope
-    assert_equal '1', Liquid::Template.parse( '{{ context.scopes }}'  ).render!('context' => ContextDrop.new)
-    assert_equal '2', Liquid::Template.parse( '{%for i in dummy%}{{ context.scopes }}{%endfor%}'  ).render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal '3', Liquid::Template.parse( '{%for i in dummy%}{%for i in dummy%}{{ context.scopes }}{%endfor%}{%endfor%}'  ).render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal '1', Liquid::Template.parse('{{ context.scopes }}').render!('context' => ContextDrop.new)
+    assert_equal '2', Liquid::Template.parse('{%for i in dummy%}{{ context.scopes }}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal '3', Liquid::Template.parse('{%for i in dummy%}{%for i in dummy%}{{ context.scopes }}{%endfor%}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1])
   end
 
   def test_scope_though_proc
-    assert_equal '1', Liquid::Template.parse( '{{ s }}'  ).render!('context' => ContextDrop.new, 's' => Proc.new{|c| c['context.scopes'] })
-    assert_equal '2', Liquid::Template.parse( '{%for i in dummy%}{{ s }}{%endfor%}'  ).render!('context' => ContextDrop.new, 's' => Proc.new{|c| c['context.scopes'] }, 'dummy' => [1])
-    assert_equal '3', Liquid::Template.parse( '{%for i in dummy%}{%for i in dummy%}{{ s }}{%endfor%}{%endfor%}'  ).render!('context' => ContextDrop.new, 's' => Proc.new{|c| c['context.scopes'] }, 'dummy' => [1])
+    assert_equal '1', Liquid::Template.parse('{{ s }}').render!('context' => ContextDrop.new, 's' => proc { |c| c['context.scopes'] })
+    assert_equal '2', Liquid::Template.parse('{%for i in dummy%}{{ s }}{%endfor%}').render!('context' => ContextDrop.new, 's' => proc { |c| c['context.scopes'] }, 'dummy' => [1])
+    assert_equal '3', Liquid::Template.parse('{%for i in dummy%}{%for i in dummy%}{{ s }}{%endfor%}{%endfor%}').render!('context' => ContextDrop.new, 's' => proc { |c| c['context.scopes'] }, 'dummy' => [1])
   end
 
   def test_scope_with_assigns
-    assert_equal 'variable', Liquid::Template.parse( '{% assign a = "variable"%}{{a}}'  ).render!('context' => ContextDrop.new)
-    assert_equal 'variable', Liquid::Template.parse( '{% assign a = "variable"%}{%for i in dummy%}{{a}}{%endfor%}'  ).render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal 'test', Liquid::Template.parse( '{% assign header_gif = "test"%}{{header_gif}}'  ).render!('context' => ContextDrop.new)
-    assert_equal 'test', Liquid::Template.parse( "{% assign header_gif = 'test'%}{{header_gif}}"  ).render!('context' => ContextDrop.new)
+    assert_equal 'variable', Liquid::Template.parse('{% assign a = "variable"%}{{a}}').render!('context' => ContextDrop.new)
+    assert_equal 'variable', Liquid::Template.parse('{% assign a = "variable"%}{%for i in dummy%}{{a}}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal 'test', Liquid::Template.parse('{% assign header_gif = "test"%}{{header_gif}}').render!('context' => ContextDrop.new)
+    assert_equal 'test', Liquid::Template.parse("{% assign header_gif = 'test'%}{{header_gif}}").render!('context' => ContextDrop.new)
   end
 
   def test_scope_from_tags
-    assert_equal '1', Liquid::Template.parse( '{% for i in context.scopes_as_array %}{{i}}{% endfor %}'  ).render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal '12', Liquid::Template.parse( '{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}'  ).render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal '123', Liquid::Template.parse( '{%for a in dummy%}{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}{% endfor %}'  ).render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal '1', Liquid::Template.parse('{% for i in context.scopes_as_array %}{{i}}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal '12', Liquid::Template.parse('{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal '123', Liquid::Template.parse('{%for a in dummy%}{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1])
   end
 
   def test_access_context_from_drop
-    assert_equal '123', Liquid::Template.parse( '{%for a in dummy%}{{ context.loop_pos }}{% endfor %}'  ).render!('context' => ContextDrop.new, 'dummy' => [1,2,3])
+    assert_equal '123', Liquid::Template.parse('{%for a in dummy%}{{ context.loop_pos }}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1, 2, 3])
   end
 
   def test_enumerable_drop
-    assert_equal '123', Liquid::Template.parse( '{% for c in collection %}{{c}}{% endfor %}').render!('collection' => EnumerableDrop.new)
+    assert_equal '123', Liquid::Template.parse('{% for c in collection %}{{c}}{% endfor %}').render!('collection' => EnumerableDrop.new)
   end
 
   def test_enumerable_drop_size
-    assert_equal '3', Liquid::Template.parse( '{{collection.size}}').render!('collection' => EnumerableDrop.new)
+    assert_equal '3', Liquid::Template.parse('{{collection.size}}').render!('collection' => EnumerableDrop.new)
   end
 
-  def test_enumerable_drop_will_invoke_before_method_for_clashing_method_names
-    ["select", "each", "map", "cycle"].each do |method|
+  def test_enumerable_drop_will_invoke_liquid_method_missing_for_clashing_method_names
+    %w[select each map cycle].each do |method|
       assert_equal method.to_s, Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
       assert_equal method.to_s, Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
       assert_equal method.to_s, Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
@@ -213,20 +243,20 @@ class DropsTest < Test::Unit::TestCase
   end
 
   def test_some_enumerable_methods_still_get_invoked
-    [ :count, :max ].each do |method|
-      assert_equal "3", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "3", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "3", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
-      assert_equal "3", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
+    %i[count max].each do |method|
+      assert_equal '3', Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
+      assert_equal '3', Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new)
+      assert_equal '3', Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
+      assert_equal '3', Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
     end
 
-    assert_equal "yes", Liquid::Template.parse("{% if collection contains 3 %}yes{% endif %}").render!('collection' => RealEnumerableDrop.new)
+    assert_equal 'yes', Liquid::Template.parse('{% if collection contains 3 %}yes{% endif %}').render!('collection' => RealEnumerableDrop.new)
 
-    [ :min, :first ].each do |method|
-      assert_equal "1", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "1", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "1", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
-      assert_equal "1", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
+    %i[min first].each do |method|
+      assert_equal '1', Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
+      assert_equal '1', Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new)
+      assert_equal '1', Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
+      assert_equal '1', Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
     end
   end
 
@@ -239,7 +269,7 @@ class DropsTest < Test::Unit::TestCase
   end
 
   def test_default_to_s_on_drops
-    assert_equal 'ProductDrop', Liquid::Template.parse("{{ product }}").render!('product' => ProductDrop.new)
+    assert_equal 'ProductDrop', Liquid::Template.parse('{{ product }}').render!('product' => ProductDrop.new)
     assert_equal 'EnumerableDrop', Liquid::Template.parse('{{ collection }}').render!('collection' => EnumerableDrop.new)
   end
 end # DropsTest

test/integration/error_handling_test.rb

@@ -1,110 +1,263 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-class ErrorDrop < Liquid::Drop
-  def standard_error
-    raise Liquid::StandardError, 'standard error'
-  end
-
-  def argument_error
-    raise Liquid::ArgumentError, 'argument error'
-  end
-
-  def syntax_error
-    raise Liquid::SyntaxError, 'syntax error'
-  end
-
-  def exception
-    raise Exception, 'exception'
-  end
-
-end
-
-class ErrorHandlingTest < Test::Unit::TestCase
+class ErrorHandlingTest < Minitest::Test
   include Liquid
 
-  def test_standard_error
-    assert_nothing_raised do
-      template = Liquid::Template.parse( ' {{ errors.standard_error }} '  )
-      assert_equal ' Liquid error: standard error ', template.render('errors' => ErrorDrop.new)
+  def test_templates_parsed_with_line_numbers_renders_them_in_errors
+    template = <<-LIQUID
+      Hello,
 
-      assert_equal 1, template.errors.size
-      assert_equal StandardError, template.errors.first.class
-    end
+      {{ errors.standard_error }} will raise a standard error.
+
+      Bla bla test.
+
+      {{ errors.syntax_error }} will raise a syntax error.
+
+      This is an argument error: {{ errors.argument_error }}
+
+      Bla.
+    LIQUID
+
+    expected = <<-TEXT
+      Hello,
+
+      Liquid error (line 3): standard error will raise a standard error.
+
+      Bla bla test.
+
+      Liquid syntax error (line 7): syntax error will raise a syntax error.
+
+      This is an argument error: Liquid error (line 9): argument error
+
+      Bla.
+    TEXT
+
+    output = Liquid::Template.parse(template, line_numbers: true).render('errors' => ErrorDrop.new)
+    assert_equal expected, output
+  end
+
+  def test_standard_error
+    template = Liquid::Template.parse(' {{ errors.standard_error }} ')
+    assert_equal ' Liquid error: standard error ', template.render('errors' => ErrorDrop.new)
+
+    assert_equal 1, template.errors.size
+    assert_equal StandardError, template.errors.first.class
   end
 
   def test_syntax
+    template = Liquid::Template.parse(' {{ errors.syntax_error }} ')
+    assert_equal ' Liquid syntax error: syntax error ', template.render('errors' => ErrorDrop.new)
 
-    assert_nothing_raised do
-
-      template = Liquid::Template.parse( ' {{ errors.syntax_error }} '  )
-      assert_equal ' Liquid syntax error: syntax error ', template.render('errors' => ErrorDrop.new)
-
-      assert_equal 1, template.errors.size
-      assert_equal SyntaxError, template.errors.first.class
-
-    end
+    assert_equal 1, template.errors.size
+    assert_equal SyntaxError, template.errors.first.class
   end
 
   def test_argument
-    assert_nothing_raised do
+    template = Liquid::Template.parse(' {{ errors.argument_error }} ')
+    assert_equal ' Liquid error: argument error ', template.render('errors' => ErrorDrop.new)
 
-      template = Liquid::Template.parse( ' {{ errors.argument_error }} '  )
-      assert_equal ' Liquid error: argument error ', template.render('errors' => ErrorDrop.new)
-
-      assert_equal 1, template.errors.size
-      assert_equal ArgumentError, template.errors.first.class
-    end
+    assert_equal 1, template.errors.size
+    assert_equal ArgumentError, template.errors.first.class
   end
 
   def test_missing_endtag_parse_time_error
-    assert_raise(Liquid::SyntaxError) do
+    assert_raises(Liquid::SyntaxError) do
       Liquid::Template.parse(' {% for a in b %} ... ')
     end
   end
 
   def test_unrecognized_operator
     with_error_mode(:strict) do
-      assert_raise(SyntaxError) do
+      assert_raises(SyntaxError) do
         Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ')
       end
     end
   end
-  
+
   def test_lax_unrecognized_operator
-    assert_nothing_raised do
-      template = Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', :error_mode => :lax)
-      assert_equal ' Liquid error: Unknown operator =! ', template.render
-      assert_equal 1, template.errors.size
-      assert_equal Liquid::ArgumentError, template.errors.first.class
+    template = Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', error_mode: :lax)
+    assert_equal ' Liquid error: Unknown operator =! ', template.render
+    assert_equal 1, template.errors.size
+    assert_equal Liquid::ArgumentError, template.errors.first.class
+  end
+
+  def test_with_line_numbers_adds_numbers_to_parser_errors
+    err = assert_raises(SyntaxError) do
+      Liquid::Template.parse('
+          foobar
+
+          {% "cat" | foobar %}
+
+          bla
+        ',
+                             line_numbers: true)
     end
+
+    assert_match(/Liquid syntax error \(line 4\)/, err.message)
+  end
+
+  def test_with_line_numbers_adds_numbers_to_parser_errors_with_whitespace_trim
+    err = assert_raises(SyntaxError) do
+      Liquid::Template.parse('
+          foobar
+
+          {%- "cat" | foobar -%}
+
+          bla
+        ',
+                             line_numbers: true)
+    end
+
+    assert_match(/Liquid syntax error \(line 4\)/, err.message)
+  end
+
+  def test_parsing_warn_with_line_numbers_adds_numbers_to_lexer_errors
+    template = Liquid::Template.parse('
+        foobar
+
+        {% if 1 =! 2 %}ok{% endif %}
+
+        bla
+            ',
+                                      error_mode: :warn,
+                                      line_numbers: true)
+
+    assert_equal ['Liquid syntax error (line 4): Unexpected character = in "1 =! 2"'],
+                 template.warnings.map(&:message)
+  end
+
+  def test_parsing_strict_with_line_numbers_adds_numbers_to_lexer_errors
+    err = assert_raises(SyntaxError) do
+      Liquid::Template.parse('
+          foobar
+
+          {% if 1 =! 2 %}ok{% endif %}
+
+          bla
+                ',
+                             error_mode: :strict,
+                             line_numbers: true)
+    end
+
+    assert_equal 'Liquid syntax error (line 4): Unexpected character = in "1 =! 2"', err.message
+  end
+
+  def test_syntax_errors_in_nested_blocks_have_correct_line_number
+    err = assert_raises(SyntaxError) do
+      Liquid::Template.parse('
+          foobar
+
+          {% if 1 != 2 %}
+            {% foo %}
+          {% endif %}
+
+          bla
+                ',
+                             line_numbers: true)
+    end
+
+    assert_equal "Liquid syntax error (line 5): Unknown tag 'foo'", err.message
   end
 
   def test_strict_error_messages
-    err = assert_raise(SyntaxError) do
-      Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', :error_mode => :strict)
+    err = assert_raises(SyntaxError) do
+      Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', error_mode: :strict)
     end
-    assert_equal 'Unexpected character = in "1 =! 2"', err.message
+    assert_equal 'Liquid syntax error: Unexpected character = in "1 =! 2"', err.message
 
-    err = assert_raise(SyntaxError) do
-      Liquid::Template.parse('{{%%%}}', :error_mode => :strict)
+    err = assert_raises(SyntaxError) do
+      Liquid::Template.parse('{{%%%}}', error_mode: :strict)
     end
-    assert_equal 'Unexpected character % in "{{%%%}}"', err.message
+    assert_equal 'Liquid syntax error: Unexpected character % in "{{%%%}}"', err.message
   end
 
   def test_warnings
-    template = Liquid::Template.parse('{% if ~~~ %}{{%%%}}{% else %}{{ hello. }}{% endif %}', :error_mode => :warn)
+    template = Liquid::Template.parse('{% if ~~~ %}{{%%%}}{% else %}{{ hello. }}{% endif %}', error_mode: :warn)
     assert_equal 3, template.warnings.size
-    assert_equal 'Unexpected character ~ in "~~~"', template.warnings[0].message
-    assert_equal 'Unexpected character % in "{{%%%}}"', template.warnings[1].message
-    assert_equal 'Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].message
+    assert_equal 'Unexpected character ~ in "~~~"', template.warnings[0].to_s(false)
+    assert_equal 'Unexpected character % in "{{%%%}}"', template.warnings[1].to_s(false)
+    assert_equal 'Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].to_s(false)
     assert_equal '', template.render
   end
 
+  def test_warning_line_numbers
+    template = Liquid::Template.parse("{% if ~~~ %}\n{{%%%}}{% else %}\n{{ hello. }}{% endif %}", error_mode: :warn, line_numbers: true)
+    assert_equal 'Liquid syntax error (line 1): Unexpected character ~ in "~~~"', template.warnings[0].message
+    assert_equal 'Liquid syntax error (line 2): Unexpected character % in "{{%%%}}"', template.warnings[1].message
+    assert_equal 'Liquid syntax error (line 3): Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].message
+    assert_equal 3, template.warnings.size
+    assert_equal [1, 2, 3], template.warnings.map(&:line_number)
+  end
+
   # Liquid should not catch Exceptions that are not subclasses of StandardError, like Interrupt and NoMemoryError
   def test_exceptions_propagate
-    assert_raise Exception do
-      template = Liquid::Template.parse( ' {{ errors.exception }} '  )
+    assert_raises Exception do
+      template = Liquid::Template.parse('{{ errors.exception }}')
       template.render('errors' => ErrorDrop.new)
     end
   end
-end # ErrorHandlingTest
+
+  def test_default_exception_renderer_with_internal_error
+    template = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
+
+    output = template.render('errors' => ErrorDrop.new)
+
+    assert_equal 'This is a runtime error: Liquid error (line 1): internal', output
+    assert_equal [Liquid::InternalError], template.errors.map(&:class)
+  end
+
+  def test_setting_default_exception_renderer
+    old_exception_renderer = Liquid::Template.default_exception_renderer
+    exceptions = []
+    Liquid::Template.default_exception_renderer = lambda { |e|
+      exceptions << e
+      ''
+    }
+    template = Liquid::Template.parse('This is a runtime error: {{ errors.argument_error }}')
+
+    output = template.render('errors' => ErrorDrop.new)
+
+    assert_equal 'This is a runtime error: ', output
+    assert_equal [Liquid::ArgumentError], template.errors.map(&:class)
+  ensure
+    Liquid::Template.default_exception_renderer = old_exception_renderer if old_exception_renderer
+  end
+
+  def test_exception_renderer_exposing_non_liquid_error
+    template = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
+    exceptions = []
+    handler = lambda { |e|
+      exceptions << e
+      e.cause
+    }
+
+    output = template.render({ 'errors' => ErrorDrop.new }, exception_renderer: handler)
+
+    assert_equal 'This is a runtime error: runtime error', output
+    assert_equal [Liquid::InternalError], exceptions.map(&:class)
+    assert_equal exceptions, template.errors
+    assert_equal '#<RuntimeError: runtime error>', exceptions.first.cause.inspect
+  end
+
+  class TestFileSystem
+    def read_template_file(_template_path)
+      '{{ errors.argument_error }}'
+    end
+  end
+
+  def test_included_template_name_with_line_numbers
+    old_file_system = Liquid::Template.file_system
+
+    begin
+      Liquid::Template.file_system = TestFileSystem.new
+      template = Liquid::Template.parse("Argument error:\n{% include 'product' %}", line_numbers: true)
+      page = template.render('errors' => ErrorDrop.new)
+    ensure
+      Liquid::Template.file_system = old_file_system
+    end
+    assert_equal "Argument error:\nLiquid error (product line 1): argument error", page
+    assert_equal 'product', template.errors.first.template_name
+  end
+end

test/integration/filter_test.rb

@@ -1,30 +1,38 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 module MoneyFilter
   def money(input)
-    sprintf(' %d$ ', input)
+    format(' %d$ ', input)
   end
 
   def money_with_underscore(input)
-    sprintf(' %d$ ', input)
+    format(' %d$ ', input)
   end
 end
 
 module CanadianMoneyFilter
   def money(input)
-    sprintf(' %d$ CAD ', input)
+    format(' %d$ CAD ', input)
   end
 end
 
 module SubstituteFilter
-  def substitute(input, params={})
-    input.gsub(/%\{(\w+)\}/) { |match| params[$1] }
+  def substitute(input, params = {})
+    input.gsub(/%\{(\w+)\}/) { |_match| params[Regexp.last_match(1)] }
   end
 end
 
-class FiltersTest < Test::Unit::TestCase
+class FiltersTest < Minitest::Test
   include Liquid
 
+  module OverrideObjectMethodFilter
+    def tap(_input)
+      'tap overridden'
+    end
+  end
+
   def setup
     @context = Context.new
   end
@@ -33,13 +41,13 @@ class FiltersTest < Test::Unit::TestCase
     @context['var'] = 1000
     @context.add_filters(MoneyFilter)
 
-    assert_equal ' 1000$ ', Variable.new("var | money").render(@context)
+    assert_equal ' 1000$ ', Template.parse('{{var | money}}').render(@context)
   end
 
   def test_underscore_in_filter_name
     @context['var'] = 1000
     @context.add_filters(MoneyFilter)
-    assert_equal ' 1000$ ', Variable.new("var | money_with_underscore").render(@context)
+    assert_equal ' 1000$ ', Template.parse('{{var | money_with_underscore}}').render(@context)
   end
 
   def test_second_filter_overwrites_first
@@ -47,79 +55,126 @@ class FiltersTest < Test::Unit::TestCase
     @context.add_filters(MoneyFilter)
     @context.add_filters(CanadianMoneyFilter)
 
-    assert_equal ' 1000$ CAD ', Variable.new("var | money").render(@context)
+    assert_equal ' 1000$ CAD ', Template.parse('{{var | money}}').render(@context)
   end
 
   def test_size
     @context['var'] = 'abcd'
     @context.add_filters(MoneyFilter)
 
-    assert_equal 4, Variable.new("var | size").render(@context)
+    assert_equal '4', Template.parse('{{var | size}}').render(@context)
   end
 
   def test_join
-    @context['var'] = [1,2,3,4]
+    @context['var'] = [1, 2, 3, 4]
 
-    assert_equal "1 2 3 4", Variable.new("var | join").render(@context)
+    assert_equal '1 2 3 4', Template.parse('{{var | join}}').render(@context)
   end
 
   def test_sort
     @context['value'] = 3
-    @context['numbers'] = [2,1,4,3]
-    @context['words'] = ['expected', 'as', 'alphabetic']
-    @context['arrays'] = ['flower', 'are']
+    @context['numbers'] = [2, 1, 4, 3]
+    @context['words'] = %w[expected as alphabetic]
+    @context['arrays'] = %w[flower are]
+    @context['case_sensitive'] = %w[sensitive Expected case]
 
-    assert_equal [1,2,3,4], Variable.new("numbers | sort").render(@context)
-    assert_equal ['alphabetic', 'as', 'expected'], Variable.new("words | sort").render(@context)
-    assert_equal [3], Variable.new("value | sort").render(@context)
-    assert_equal ['are', 'flower'], Variable.new("arrays | sort").render(@context)
+    assert_equal '1 2 3 4', Template.parse('{{numbers | sort | join}}').render(@context)
+    assert_equal 'alphabetic as expected', Template.parse('{{words | sort | join}}').render(@context)
+    assert_equal '3', Template.parse('{{value | sort}}').render(@context)
+    assert_equal 'are flower', Template.parse('{{arrays | sort | join}}').render(@context)
+    assert_equal 'Expected case sensitive', Template.parse('{{case_sensitive | sort | join}}').render(@context)
+  end
+
+  def test_sort_natural
+    @context['words'] = %w[case Assert Insensitive]
+    @context['hashes'] = [{ 'a' => 'A' }, { 'a' => 'b' }, { 'a' => 'C' }]
+    @context['objects'] = [TestObject.new('A'), TestObject.new('b'), TestObject.new('C')]
+
+    # Test strings
+    assert_equal 'Assert case Insensitive', Template.parse('{{words | sort_natural | join}}').render(@context)
+
+    # Test hashes
+    assert_equal 'A b C', Template.parse("{{hashes | sort_natural: 'a' | map: 'a' | join}}").render(@context)
+
+    # Test objects
+    assert_equal 'A b C', Template.parse("{{objects | sort_natural: 'a' | map: 'a' | join}}").render(@context)
+  end
+
+  def test_compact
+    @context['words'] = ['a', nil, 'b', nil, 'c']
+    @context['hashes'] = [{ 'a' => 'A' }, { 'a' => nil }, { 'a' => 'C' }]
+    @context['objects'] = [TestObject.new('A'), TestObject.new(nil), TestObject.new('C')]
+
+    # Test strings
+    assert_equal 'a b c', Template.parse('{{words | compact | join}}').render(@context)
+
+    # Test hashes
+    assert_equal 'A C', Template.parse("{{hashes | compact: 'a' | map: 'a' | join}}").render(@context)
+
+    # Test objects
+    assert_equal 'A C', Template.parse("{{objects | compact: 'a' | map: 'a' | join}}").render(@context)
   end
 
   def test_strip_html
-    @context['var'] = "<b>bla blub</a>"
+    @context['var'] = '<b>bla blub</a>'
 
-    assert_equal "bla blub", Variable.new("var | strip_html").render(@context)
+    assert_equal 'bla blub', Template.parse('{{ var | strip_html }}').render(@context)
   end
 
   def test_strip_html_ignore_comments_with_html
-    @context['var'] = "<!-- split and some <ul> tag --><b>bla blub</a>"
+    @context['var'] = '<!-- split and some <ul> tag --><b>bla blub</a>'
 
-    assert_equal "bla blub", Variable.new("var | strip_html").render(@context)
+    assert_equal 'bla blub', Template.parse('{{ var | strip_html }}').render(@context)
   end
 
   def test_capitalize
-    @context['var'] = "blub"
+    @context['var'] = 'blub'
 
-    assert_equal "Blub", Variable.new("var | capitalize").render(@context)
+    assert_equal 'Blub', Template.parse('{{ var | capitalize }}').render(@context)
   end
 
   def test_nonexistent_filter_is_ignored
     @context['var'] = 1000
 
-    assert_equal 1000, Variable.new("var | xyzzy").render(@context)
+    assert_equal '1000', Template.parse('{{ var | xyzzy }}').render(@context)
   end
 
   def test_filter_with_keyword_arguments
     @context['surname'] = 'john'
+    @context['input'] = 'hello %{first_name}, %{last_name}'
     @context.add_filters(SubstituteFilter)
-    output = Variable.new(%! 'hello %{first_name}, %{last_name}' | substitute: first_name: surname, last_name: 'doe' !).render(@context)
+    output = Template.parse(%({{ input | substitute: first_name: surname, last_name: 'doe' }})).render(@context)
     assert_equal 'hello john, doe', output
   end
+
+  def test_override_object_method_in_filter
+    assert_equal 'tap overridden', Template.parse('{{var | tap}}').render!({ 'var' => 1000 }, filters: [OverrideObjectMethodFilter])
+
+    # tap still treated as a non-existent filter
+    assert_equal '1000', Template.parse('{{var | tap}}').render!('var' => 1000)
+  end
 end
 
-class FiltersInTemplate < Test::Unit::TestCase
+class FiltersInTemplate < Minitest::Test
   include Liquid
 
   def test_local_global
-    Template.register_filter(MoneyFilter)
-
-    assert_equal " 1000$ ", Template.parse("{{1000 | money}}").render!(nil, nil)
-    assert_equal " 1000$ CAD ", Template.parse("{{1000 | money}}").render!(nil, :filters => CanadianMoneyFilter)
-    assert_equal " 1000$ CAD ", Template.parse("{{1000 | money}}").render!(nil, :filters => [CanadianMoneyFilter])
+    with_global_filter(MoneyFilter) do
+      assert_equal ' 1000$ ', Template.parse('{{1000 | money}}').render!(nil, nil)
+      assert_equal ' 1000$ CAD ', Template.parse('{{1000 | money}}').render!(nil, filters: CanadianMoneyFilter)
+      assert_equal ' 1000$ CAD ', Template.parse('{{1000 | money}}').render!(nil, filters: [CanadianMoneyFilter])
+    end
   end
 
   def test_local_filter_with_deprecated_syntax
-    assert_equal " 1000$ CAD ", Template.parse("{{1000 | money}}").render!(nil, CanadianMoneyFilter)
-    assert_equal " 1000$ CAD ", Template.parse("{{1000 | money}}").render!(nil, [CanadianMoneyFilter])
+    assert_equal ' 1000$ CAD ', Template.parse('{{1000 | money}}').render!(nil, CanadianMoneyFilter)
+    assert_equal ' 1000$ CAD ', Template.parse('{{1000 | money}}').render!(nil, [CanadianMoneyFilter])
   end
 end # FiltersTest
+
+class TestObject < Liquid::Drop
+  attr_accessor :a
+  def initialize(a)
+    @a = a
+  end
+end

test/integration/hash_ordering_test.rb

@@ -1,25 +1,25 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-module MoneyFilter
-  def money(input)
-    sprintf(' %d$ ', input)
+class HashOrderingTest < Minitest::Test
+  module MoneyFilter
+    def money(input)
+      format(' %d$ ', input)
+    end
   end
-end
 
-module CanadianMoneyFilter
-  def money(input)
-    sprintf(' %d$ CAD ', input)
+  module CanadianMoneyFilter
+    def money(input)
+      format(' %d$ CAD ', input)
+    end
   end
-end
 
-class HashOrderingTest < Test::Unit::TestCase
   include Liquid
 
- def test_global_register_order
-    Template.register_filter(MoneyFilter)
-    Template.register_filter(CanadianMoneyFilter)
-
-    assert_equal " 1000$ CAD ", Template.parse("{{1000 | money}}").render(nil, nil)
- end
-
+  def test_global_register_order
+    with_global_filter(MoneyFilter, CanadianMoneyFilter) do
+      assert_equal ' 1000$ CAD ', Template.parse('{{1000 | money}}').render(nil, nil)
+    end
+  end
 end

test/integration/legacy_test.rb

@@ -0,0 +1,13 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+require 'liquid/legacy'
+
+class FiltersTest < Minitest::Test
+  include Liquid
+
+  def test_constants
+    assert_equal Liquid::FilterSeparator, Liquid::FILTER_SEPARATOR
+    assert_equal Liquid::BlockBody::ContentOfVariable, Liquid::BlockBody::CONTENT_OF_VARIABLE
+  end
+end

test/integration/output_test.rb

@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 module FunnyFilter
-  def make_funny(input)
+  def make_funny(_input)
     'LOL'
   end
 
@@ -9,12 +11,12 @@ module FunnyFilter
     "LOL: #{input}"
   end
 
-  def add_smiley(input, smiley = ":-)")
+  def add_smiley(input, smiley = ':-)')
     "#{input} #{smiley}"
   end
 
-  def add_tag(input, tag = "p", id = "foo")
-    %|<#{tag} id="#{id}">#{input}</#{tag}>|
+  def add_tag(input, tag = 'p', id = 'foo')
+    %(<#{tag} id="#{id}">#{input}</#{tag}>)
   end
 
   def paragraph(input)
@@ -22,95 +24,102 @@ module FunnyFilter
   end
 
   def link_to(name, url)
-    %|<a href="#{url}">#{name}</a>|
+    %(<a href="#{url}">#{name}</a>)
   end
-
 end
 
-class OutputTest < Test::Unit::TestCase
+class OutputTest < Minitest::Test
   include Liquid
 
   def setup
     @assigns = {
       'best_cars' => 'bmw',
-      'car' => {'bmw' => 'good', 'gm' => 'bad'}
-      }
+      'car' => { 'bmw' => 'good', 'gm' => 'bad' },
+    }
   end
 
   def test_variable
-    text = %| {{best_cars}} |
+    text = %( {{best_cars}} )
 
-    expected = %| bmw |
+    expected = %( bmw )
     assert_equal expected, Template.parse(text).render!(@assigns)
   end
 
-  def test_variable_traversing
-    text = %| {{car.bmw}} {{car.gm}} {{car.bmw}} |
+  def test_variable_traversing_with_two_brackets
+    text = %({{ site.data.menu[include.menu][include.locale] }})
+    assert_equal 'it works!', Template.parse(text).render!(
+      'site' => { 'data' => { 'menu' => { 'foo' => { 'bar' => 'it works!' } } } },
+      'include' => { 'menu' => 'foo', 'locale' => 'bar' }
+    )
+  end
 
-    expected = %| good bad good |
+  def test_variable_traversing
+    text = %( {{car.bmw}} {{car.gm}} {{car.bmw}} )
+
+    expected = %( good bad good )
     assert_equal expected, Template.parse(text).render!(@assigns)
   end
 
   def test_variable_piping
     text = %( {{ car.gm | make_funny }} )
-    expected = %| LOL |
+    expected = %( LOL )
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_variable_piping_with_input
     text = %( {{ car.gm | cite_funny }} )
-    expected = %| LOL: bad |
+    expected = %( LOL: bad )
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_variable_piping_with_args
     text = %! {{ car.gm | add_smiley : ':-(' }} !
     expected = %| bad :-( |
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_variable_piping_with_no_args
-    text = %! {{ car.gm | add_smiley }} !
+    text = %( {{ car.gm | add_smiley }} )
     expected = %| bad :-) |
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_multiple_variable_piping_with_args
     text = %! {{ car.gm | add_smiley : ':-(' | add_smiley : ':-('}} !
     expected = %| bad :-( :-( |
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_variable_piping_with_multiple_args
-    text = %! {{ car.gm | add_tag : 'span', 'bar'}} !
-    expected = %| <span id="bar">bad</span> |
+    text = %( {{ car.gm | add_tag : 'span', 'bar'}} )
+    expected = %( <span id="bar">bad</span> )
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_variable_piping_with_variable_args
-    text = %! {{ car.gm | add_tag : 'span', car.bmw}} !
-    expected = %| <span id="good">bad</span> |
+    text = %( {{ car.gm | add_tag : 'span', car.bmw}} )
+    expected = %( <span id="good">bad</span> )
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_multiple_pipings
     text = %( {{ best_cars | cite_funny | paragraph }} )
-    expected = %| <p>LOL: bmw</p> |
+    expected = %( <p>LOL: bmw</p> )
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 
   def test_link_to
     text = %( {{ 'Typo' | link_to: 'http://typo.leetsoft.com' }} )
-    expected = %| <a href="http://typo.leetsoft.com">Typo</a> |
+    expected = %( <a href="http://typo.leetsoft.com">Typo</a> )
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => [FunnyFilter])
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: [FunnyFilter])
   end
 end # OutputTest

test/integration/parse_tree_visitor_test.rb

@@ -0,0 +1,247 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ParseTreeVisitorTest < Minitest::Test
+  include Liquid
+
+  def test_variable
+    assert_equal(
+      ['test'],
+      visit(%({{ test }}))
+    )
+  end
+
+  def test_varible_with_filter
+    assert_equal(
+      %w[test infilter],
+      visit(%({{ test | split: infilter }}))
+    )
+  end
+
+  def test_dynamic_variable
+    assert_equal(
+      %w[test inlookup],
+      visit(%({{ test[inlookup] }}))
+    )
+  end
+
+  def test_if_condition
+    assert_equal(
+      ['test'],
+      visit(%({% if test %}{% endif %}))
+    )
+  end
+
+  def test_complex_if_condition
+    assert_equal(
+      ['test'],
+      visit(%({% if 1 == 1 and 2 == test %}{% endif %}))
+    )
+  end
+
+  def test_if_body
+    assert_equal(
+      ['test'],
+      visit(%({% if 1 == 1 %}{{ test }}{% endif %}))
+    )
+  end
+
+  def test_unless_condition
+    assert_equal(
+      ['test'],
+      visit(%({% unless test %}{% endunless %}))
+    )
+  end
+
+  def test_complex_unless_condition
+    assert_equal(
+      ['test'],
+      visit(%({% unless 1 == 1 and 2 == test %}{% endunless %}))
+    )
+  end
+
+  def test_unless_body
+    assert_equal(
+      ['test'],
+      visit(%({% unless 1 == 1 %}{{ test }}{% endunless %}))
+    )
+  end
+
+  def test_elsif_condition
+    assert_equal(
+      ['test'],
+      visit(%({% if 1 == 1 %}{% elsif test %}{% endif %}))
+    )
+  end
+
+  def test_complex_elsif_condition
+    assert_equal(
+      ['test'],
+      visit(%({% if 1 == 1 %}{% elsif 1 == 1 and 2 == test %}{% endif %}))
+    )
+  end
+
+  def test_elsif_body
+    assert_equal(
+      ['test'],
+      visit(%({% if 1 == 1 %}{% elsif 2 == 2 %}{{ test }}{% endif %}))
+    )
+  end
+
+  def test_else_body
+    assert_equal(
+      ['test'],
+      visit(%({% if 1 == 1 %}{% else %}{{ test }}{% endif %}))
+    )
+  end
+
+  def test_case_left
+    assert_equal(
+      ['test'],
+      visit(%({% case test %}{% endcase %}))
+    )
+  end
+
+  def test_case_condition
+    assert_equal(
+      ['test'],
+      visit(%({% case 1 %}{% when test %}{% endcase %}))
+    )
+  end
+
+  def test_case_when_body
+    assert_equal(
+      ['test'],
+      visit(%({% case 1 %}{% when 2 %}{{ test }}{% endcase %}))
+    )
+  end
+
+  def test_case_else_body
+    assert_equal(
+      ['test'],
+      visit(%({% case 1 %}{% else %}{{ test }}{% endcase %}))
+    )
+  end
+
+  def test_for_in
+    assert_equal(
+      ['test'],
+      visit(%({% for x in test %}{% endfor %}))
+    )
+  end
+
+  def test_for_limit
+    assert_equal(
+      ['test'],
+      visit(%({% for x in (1..5) limit: test %}{% endfor %}))
+    )
+  end
+
+  def test_for_offset
+    assert_equal(
+      ['test'],
+      visit(%({% for x in (1..5) offset: test %}{% endfor %}))
+    )
+  end
+
+  def test_for_body
+    assert_equal(
+      ['test'],
+      visit(%({% for x in (1..5) %}{{ test }}{% endfor %}))
+    )
+  end
+
+  def test_tablerow_in
+    assert_equal(
+      ['test'],
+      visit(%({% tablerow x in test %}{% endtablerow %}))
+    )
+  end
+
+  def test_tablerow_limit
+    assert_equal(
+      ['test'],
+      visit(%({% tablerow x in (1..5) limit: test %}{% endtablerow %}))
+    )
+  end
+
+  def test_tablerow_offset
+    assert_equal(
+      ['test'],
+      visit(%({% tablerow x in (1..5) offset: test %}{% endtablerow %}))
+    )
+  end
+
+  def test_tablerow_body
+    assert_equal(
+      ['test'],
+      visit(%({% tablerow x in (1..5) %}{{ test }}{% endtablerow %}))
+    )
+  end
+
+  def test_cycle
+    assert_equal(
+      ['test'],
+      visit(%({% cycle test %}))
+    )
+  end
+
+  def test_assign
+    assert_equal(
+      ['test'],
+      visit(%({% assign x = test %}))
+    )
+  end
+
+  def test_capture
+    assert_equal(
+      ['test'],
+      visit(%({% capture x %}{{ test }}{% endcapture %}))
+    )
+  end
+
+  def test_include
+    assert_equal(
+      ['test'],
+      visit(%({% include test %}))
+    )
+  end
+
+  def test_include_with
+    assert_equal(
+      ['test'],
+      visit(%({% include "hai" with test %}))
+    )
+  end
+
+  def test_include_for
+    assert_equal(
+      ['test'],
+      visit(%({% include "hai" for test %}))
+    )
+  end
+
+  def test_preserve_tree_structure
+    assert_equal(
+      [[nil, [
+        [nil, [[nil, [['other', []]]]]],
+        ['test', []],
+        ['xs', []],
+      ]]],
+      traversal(%({% for x in xs offset: test %}{{ other }}{% endfor %})).visit
+    )
+  end
+
+  private
+
+  def traversal(template)
+    ParseTreeVisitor
+      .for(Template.parse(template).root)
+      .add_callback_for(VariableLookup, &:name)
+  end
+
+  def visit(template)
+    traversal(template).visit.flatten.compact
+  end
+end

test/integration/parsing_quirks_test.rb

@@ -1,46 +1,49 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-class ParsingQuirksTest < Test::Unit::TestCase
+class ParsingQuirksTest < Minitest::Test
   include Liquid
 
   def test_parsing_css
-    text = " div { font-weight: bold; } "
+    text = ' div { font-weight: bold; } '
     assert_equal text, Template.parse(text).render!
   end
 
   def test_raise_on_single_close_bracet
-    assert_raise(SyntaxError) do
-      Template.parse("text {{method} oh nos!")
+    assert_raises(SyntaxError) do
+      Template.parse('text {{method} oh nos!')
     end
   end
 
   def test_raise_on_label_and_no_close_bracets
-    assert_raise(SyntaxError) do
-      Template.parse("TEST {{ ")
+    assert_raises(SyntaxError) do
+      Template.parse('TEST {{ ')
     end
   end
 
   def test_raise_on_label_and_no_close_bracets_percent
-    assert_raise(SyntaxError) do
-      Template.parse("TEST {% ")
+    assert_raises(SyntaxError) do
+      Template.parse('TEST {% ')
     end
   end
 
   def test_error_on_empty_filter
-    assert_nothing_raised do
-      Template.parse("{{test}}")
-      Template.parse("{{|test}}")
+    assert Template.parse('{{test}}')
+
+    with_error_mode(:lax) do
+      assert Template.parse('{{|test}}')
     end
+
     with_error_mode(:strict) do
-      assert_raise(SyntaxError) do
-        Template.parse("{{test |a|b|}}")
-      end
+      assert_raises(SyntaxError) { Template.parse('{{|test}}') }
+      assert_raises(SyntaxError) { Template.parse('{{test |a|b|}}') }
     end
   end
 
   def test_meaningless_parens_error
     with_error_mode(:strict) do
-      assert_raise(SyntaxError) do
+      assert_raises(SyntaxError) do
         markup = "a == 'foo' or (b == 'bar' and c == 'baz') or false"
         Template.parse("{% if #{markup} %} YES {% endif %}")
       end
@@ -49,46 +52,73 @@ class ParsingQuirksTest < Test::Unit::TestCase
 
   def test_unexpected_characters_syntax_error
     with_error_mode(:strict) do
-      assert_raise(SyntaxError) do
-        markup = "true && false"
+      assert_raises(SyntaxError) do
+        markup = 'true && false'
         Template.parse("{% if #{markup} %} YES {% endif %}")
       end
-      assert_raise(SyntaxError) do
-        markup = "false || true"
+      assert_raises(SyntaxError) do
+        markup = 'false || true'
         Template.parse("{% if #{markup} %} YES {% endif %}")
       end
     end
   end
 
   def test_no_error_on_lax_empty_filter
-    assert_nothing_raised do
-      Template.parse("{{test |a|b|}}", :error_mode => :lax)
-      Template.parse("{{test}}", :error_mode => :lax)
-      Template.parse("{{|test|}}", :error_mode => :lax)
-    end
+    assert Template.parse('{{test |a|b|}}', error_mode: :lax)
+    assert Template.parse('{{test}}', error_mode: :lax)
+    assert Template.parse('{{|test|}}', error_mode: :lax)
   end
 
   def test_meaningless_parens_lax
     with_error_mode(:lax) do
-      assigns = {'b' => 'bar', 'c' => 'baz'}
+      assigns = { 'b' => 'bar', 'c' => 'baz' }
       markup = "a == 'foo' or (b == 'bar' and c == 'baz') or false"
-      assert_template_result(' YES ',"{% if #{markup} %} YES {% endif %}", assigns)
+      assert_template_result(' YES ', "{% if #{markup} %} YES {% endif %}", assigns)
     end
   end
 
   def test_unexpected_characters_silently_eat_logic_lax
     with_error_mode(:lax) do
-      markup = "true && false"
-      assert_template_result(' YES ',"{% if #{markup} %} YES {% endif %}")
-      markup = "false || true"
-      assert_template_result('',"{% if #{markup} %} YES {% endif %}")
+      markup = 'true && false'
+      assert_template_result(' YES ', "{% if #{markup} %} YES {% endif %}")
+      markup = 'false || true'
+      assert_template_result('', "{% if #{markup} %} YES {% endif %}")
     end
   end
 
   def test_raise_on_invalid_tag_delimiter
-    assert_raise(Liquid::SyntaxError) do
+    assert_raises(Liquid::SyntaxError) do
       Template.new.parse('{% end %}')
     end
   end
 
+  def test_unanchored_filter_arguments
+    with_error_mode(:lax) do
+      assert_template_result('hi', "{{ 'hi there' | split$$$:' ' | first }}")
+
+      assert_template_result('x', "{{ 'X' | downcase) }}")
+
+      # After the messed up quotes a filter without parameters (reverse) should work
+      # but one with parameters (remove) shouldn't be detected.
+      assert_template_result('here',  "{{ 'hi there' | split:\"t\"\" | reverse | first}}")
+      assert_template_result('hi ', "{{ 'hi there' | split:\"t\"\" | remove:\"i\" | first}}")
+    end
+  end
+
+  def test_invalid_variables_work
+    with_error_mode(:lax) do
+      assert_template_result('bar', "{% assign 123foo = 'bar' %}{{ 123foo }}")
+      assert_template_result('123', "{% assign 123 = 'bar' %}{{ 123 }}")
+    end
+  end
+
+  def test_extra_dots_in_ranges
+    with_error_mode(:lax) do
+      assert_template_result('12345', '{% for i in (1...5) %}{{ i }}{% endfor %}')
+    end
+  end
+
+  def test_contains_in_id
+    assert_template_result(' YES ', '{% if containsallshipments == true %} YES {% endif %}', 'containsallshipments' => true)
+  end
 end # ParsingQuirksTest

test/integration/render_profiling_test.rb

@@ -0,0 +1,156 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class RenderProfilingTest < Minitest::Test
+  include Liquid
+
+  class ProfilingFileSystem
+    def read_template_file(template_path)
+      "Rendering template {% assign template_name = '#{template_path}'%}\n{{ template_name }}"
+    end
+  end
+
+  def setup
+    Liquid::Template.file_system = ProfilingFileSystem.new
+  end
+
+  def test_template_allows_flagging_profiling
+    t = Template.parse("{{ 'a string' | upcase }}")
+    t.render!
+
+    assert_nil t.profiler
+  end
+
+  def test_parse_makes_available_simple_profiling
+    t = Template.parse("{{ 'a string' | upcase }}", profile: true)
+    t.render!
+
+    assert_equal 1, t.profiler.length
+
+    node = t.profiler[0]
+    assert_equal " 'a string' | upcase ", node.code
+  end
+
+  def test_render_ignores_raw_strings_when_profiling
+    t = Template.parse("This is raw string\nstuff\nNewline", profile: true)
+    t.render!
+
+    assert_equal 0, t.profiler.length
+  end
+
+  def test_profiling_includes_line_numbers_of_liquid_nodes
+    t = Template.parse("{{ 'a string' | upcase }}\n{% increment test %}", profile: true)
+    t.render!
+    assert_equal 2, t.profiler.length
+
+    # {{ 'a string' | upcase }}
+    assert_equal 1, t.profiler[0].line_number
+    # {{ increment test }}
+    assert_equal 2, t.profiler[1].line_number
+  end
+
+  def test_profiling_includes_line_numbers_of_included_partials
+    t = Template.parse("{% include 'a_template' %}", profile: true)
+    t.render!
+
+    included_children = t.profiler[0].children
+
+    # {% assign template_name = 'a_template' %}
+    assert_equal 1, included_children[0].line_number
+    # {{ template_name }}
+    assert_equal 2, included_children[1].line_number
+  end
+
+  def test_profiling_times_the_rendering_of_tokens
+    t = Template.parse("{% include 'a_template' %}", profile: true)
+    t.render!
+
+    node = t.profiler[0]
+    refute_nil node.render_time
+  end
+
+  def test_profiling_times_the_entire_render
+    t = Template.parse("{% include 'a_template' %}", profile: true)
+    t.render!
+
+    assert t.profiler.total_render_time >= 0, 'Total render time was not calculated'
+  end
+
+  def test_profiling_uses_include_to_mark_children
+    t = Template.parse("{{ 'a string' | upcase }}\n{% include 'a_template' %}", profile: true)
+    t.render!
+
+    include_node = t.profiler[1]
+    assert_equal 2, include_node.children.length
+  end
+
+  def test_profiling_marks_children_with_the_name_of_included_partial
+    t = Template.parse("{{ 'a string' | upcase }}\n{% include 'a_template' %}", profile: true)
+    t.render!
+
+    include_node = t.profiler[1]
+    include_node.children.each do |child|
+      assert_equal 'a_template', child.partial
+    end
+  end
+
+  def test_profiling_supports_multiple_templates
+    t = Template.parse("{{ 'a string' | upcase }}\n{% include 'a_template' %}\n{% include 'b_template' %}", profile: true)
+    t.render!
+
+    a_template = t.profiler[1]
+    a_template.children.each do |child|
+      assert_equal 'a_template', child.partial
+    end
+
+    b_template = t.profiler[2]
+    b_template.children.each do |child|
+      assert_equal 'b_template', child.partial
+    end
+  end
+
+  def test_profiling_supports_rendering_the_same_partial_multiple_times
+    t = Template.parse("{{ 'a string' | upcase }}\n{% include 'a_template' %}\n{% include 'a_template' %}", profile: true)
+    t.render!
+
+    a_template1 = t.profiler[1]
+    a_template1.children.each do |child|
+      assert_equal 'a_template', child.partial
+    end
+
+    a_template2 = t.profiler[2]
+    a_template2.children.each do |child|
+      assert_equal 'a_template', child.partial
+    end
+  end
+
+  def test_can_iterate_over_each_profiling_entry
+    t = Template.parse("{{ 'a string' | upcase }}\n{% increment test %}", profile: true)
+    t.render!
+
+    timing_count = 0
+    t.profiler.each do |_timing|
+      timing_count += 1
+    end
+
+    assert_equal 2, timing_count
+  end
+
+  def test_profiling_marks_children_of_if_blocks
+    t = Template.parse('{% if true %} {% increment test %} {{ test }} {% endif %}', profile: true)
+    t.render!
+
+    assert_equal 1, t.profiler.length
+    assert_equal 2, t.profiler[0].children.length
+  end
+
+  def test_profiling_marks_children_of_for_blocks
+    t = Template.parse('{% for item in collection %} {{ item }} {% endfor %}', profile: true)
+    t.render!('collection' => %w[one two])
+
+    assert_equal 1, t.profiler.length
+    # Will profile each invocation of the for block
+    assert_equal 2, t.profiler[0].children.length
+  end
+end

test/integration/security_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 module SecurityFilter
@@ -6,37 +8,39 @@ module SecurityFilter
   end
 end
 
-class SecurityTest < Test::Unit::TestCase
+class SecurityTest < Minitest::Test
   include Liquid
 
+  def setup
+    @assigns = {}
+  end
+
   def test_no_instance_eval
     text = %( {{ '1+1' | instance_eval }} )
-    expected = %| 1+1 |
+    expected = %( 1+1 )
 
     assert_equal expected, Template.parse(text).render!(@assigns)
   end
 
   def test_no_existing_instance_eval
     text = %( {{ '1+1' | __instance_eval__ }} )
-    expected = %| 1+1 |
+    expected = %( 1+1 )
 
     assert_equal expected, Template.parse(text).render!(@assigns)
   end
 
-
   def test_no_instance_eval_after_mixing_in_new_filter
     text = %( {{ '1+1' | instance_eval }} )
-    expected = %| 1+1 |
+    expected = %( 1+1 )
 
     assert_equal expected, Template.parse(text).render!(@assigns)
   end
 
-
   def test_no_instance_eval_later_in_chain
     text = %( {{ '1+1' | add_one | instance_eval }} )
-    expected = %| 1+1 + 1 |
+    expected = %( 1+1 + 1 )
 
-    assert_equal expected, Template.parse(text).render!(@assigns, :filters => SecurityFilter)
+    assert_equal expected, Template.parse(text).render!(@assigns, filters: SecurityFilter)
   end
 
   def test_does_not_add_filters_to_symbol_table
@@ -55,10 +59,24 @@ class SecurityTest < Test::Unit::TestCase
     current_symbols = Symbol.all_symbols
 
     assigns = { 'drop' => Drop.new }
-    assert_equal "", Template.parse("{{ drop.custom_method_1 }}", assigns).render!
-    assert_equal "", Template.parse("{{ drop.custom_method_2 }}", assigns).render!
-    assert_equal "", Template.parse("{{ drop.custom_method_3 }}", assigns).render!
+    assert_equal '', Template.parse('{{ drop.custom_method_1 }}', assigns).render!
+    assert_equal '', Template.parse('{{ drop.custom_method_2 }}', assigns).render!
+    assert_equal '', Template.parse('{{ drop.custom_method_3 }}', assigns).render!
 
     assert_equal [], (Symbol.all_symbols - current_symbols)
   end
+
+  def test_max_depth_nested_blocks_does_not_raise_exception
+    depth = Liquid::Block::MAX_DEPTH
+    code = '{% if true %}' * depth + 'rendered' + '{% endif %}' * depth
+    assert_equal 'rendered', Template.parse(code).render!
+  end
+
+  def test_more_than_max_depth_nested_blocks_raises_exception
+    depth = Liquid::Block::MAX_DEPTH + 1
+    code = '{% if true %}' * depth + 'rendered' + '{% endif %}' * depth
+    assert_raises(Liquid::StackLevelError) do
+      Template.parse(code).render!
+    end
+  end
 end # SecurityTest

test/integration/standard_filter_test.rb

@@ -1,4 +1,4 @@
-# encoding: utf-8
+# frozen_string_literal: true
 
 require 'test_helper'
 
@@ -17,7 +17,7 @@ class TestThing
     "woot: #{@foo}"
   end
 
-  def [](whatever)
+  def [](_whatever)
     to_s
   end
 
@@ -29,7 +29,7 @@ end
 
 class TestDrop < Liquid::Drop
   def test
-    "testfoo"
+    'testfoo'
   end
 end
 
@@ -37,11 +37,21 @@ class TestEnumerable < Liquid::Drop
   include Enumerable
 
   def each(&block)
-    [ { "foo" => 1, "bar" => 2 }, { "foo" => 2, "bar" => 1 }, { "foo" => 3, "bar" => 3 } ].each(&block)
+    [{ 'foo' => 1, 'bar' => 2 }, { 'foo' => 2, 'bar' => 1 }, { 'foo' => 3, 'bar' => 3 }].each(&block)
   end
 end
 
-class StandardFiltersTest < Test::Unit::TestCase
+class NumberLikeThing < Liquid::Drop
+  def initialize(amount)
+    @amount = amount
+  end
+
+  def to_number
+    @amount
+  end
+end
+
+class StandardFiltersTest < Minitest::Test
   include Liquid
 
   def setup
@@ -49,183 +59,453 @@ class StandardFiltersTest < Test::Unit::TestCase
   end
 
   def test_size
-    assert_equal 3, @filters.size([1,2,3])
+    assert_equal 3, @filters.size([1, 2, 3])
     assert_equal 0, @filters.size([])
     assert_equal 0, @filters.size(nil)
   end
 
   def test_downcase
-    assert_equal 'testing', @filters.downcase("Testing")
+    assert_equal 'testing', @filters.downcase('Testing')
     assert_equal '', @filters.downcase(nil)
   end
 
   def test_upcase
-    assert_equal 'TESTING', @filters.upcase("Testing")
+    assert_equal 'TESTING', @filters.upcase('Testing')
     assert_equal '', @filters.upcase(nil)
   end
 
+  def test_slice
+    assert_equal 'oob', @filters.slice('foobar', 1, 3)
+    assert_equal 'oobar', @filters.slice('foobar', 1, 1000)
+    assert_equal '', @filters.slice('foobar', 1, 0)
+    assert_equal 'o', @filters.slice('foobar', 1, 1)
+    assert_equal 'bar', @filters.slice('foobar', 3, 3)
+    assert_equal 'ar', @filters.slice('foobar', -2, 2)
+    assert_equal 'ar', @filters.slice('foobar', -2, 1000)
+    assert_equal 'r', @filters.slice('foobar', -1)
+    assert_equal '', @filters.slice(nil, 0)
+    assert_equal '', @filters.slice('foobar', 100, 10)
+    assert_equal '', @filters.slice('foobar', -100, 10)
+    assert_equal 'oob', @filters.slice('foobar', '1', '3')
+    assert_raises(Liquid::ArgumentError) do
+      @filters.slice('foobar', nil)
+    end
+    assert_raises(Liquid::ArgumentError) do
+      @filters.slice('foobar', 0, '')
+    end
+  end
+
+  def test_slice_on_arrays
+    input = 'foobar'.split(//)
+    assert_equal %w[o o b], @filters.slice(input, 1, 3)
+    assert_equal %w[o o b a r], @filters.slice(input, 1, 1000)
+    assert_equal %w[], @filters.slice(input, 1, 0)
+    assert_equal %w[o], @filters.slice(input, 1, 1)
+    assert_equal %w[b a r], @filters.slice(input, 3, 3)
+    assert_equal %w[a r], @filters.slice(input, -2, 2)
+    assert_equal %w[a r], @filters.slice(input, -2, 1000)
+    assert_equal %w[r], @filters.slice(input, -1)
+    assert_equal %w[], @filters.slice(input, 100, 10)
+    assert_equal %w[], @filters.slice(input, -100, 10)
+  end
+
   def test_truncate
     assert_equal '1234...', @filters.truncate('1234567890', 7)
     assert_equal '1234567890', @filters.truncate('1234567890', 20)
     assert_equal '...', @filters.truncate('1234567890', 0)
     assert_equal '1234567890', @filters.truncate('1234567890')
-    assert_equal "测试...", @filters.truncate("测试测试测试测试", 5)
+    assert_equal '测试...', @filters.truncate('测试测试测试测试', 5)
+    assert_equal '12341', @filters.truncate('1234567890', 5, 1)
   end
 
   def test_split
-    assert_equal ['12','34'], @filters.split('12~34', '~')
-    assert_equal ['A? ',' ,Z'], @filters.split('A? ~ ~ ~ ,Z', '~ ~ ~')
+    assert_equal %w[12 34], @filters.split('12~34', '~')
+    assert_equal ['A? ', ' ,Z'], @filters.split('A? ~ ~ ~ ,Z', '~ ~ ~')
     assert_equal ['A?Z'], @filters.split('A?Z', '~')
-    # Regexp works although Liquid does not support.
-    assert_equal ['A','Z'], @filters.split('AxZ', /x/)
+    assert_equal [], @filters.split(nil, ' ')
+    assert_equal %w[A Z], @filters.split('A1Z', 1)
   end
 
   def test_escape
     assert_equal '&lt;strong&gt;', @filters.escape('<strong>')
+    assert_equal '1', @filters.escape(1)
+    assert_equal '2001-02-03', @filters.escape(Date.new(2001, 2, 3))
+    assert_nil @filters.escape(nil)
+  end
+
+  def test_h
     assert_equal '&lt;strong&gt;', @filters.h('<strong>')
+    assert_equal '1', @filters.h(1)
+    assert_equal '2001-02-03', @filters.h(Date.new(2001, 2, 3))
+    assert_nil @filters.h(nil)
   end
 
   def test_escape_once
     assert_equal '&lt;strong&gt;Hulk&lt;/strong&gt;', @filters.escape_once('&lt;strong&gt;Hulk</strong>')
   end
 
+  def test_url_encode
+    assert_equal 'foo%2B1%40example.com', @filters.url_encode('foo+1@example.com')
+    assert_equal '1', @filters.url_encode(1)
+    assert_equal '2001-02-03', @filters.url_encode(Date.new(2001, 2, 3))
+    assert_nil @filters.url_encode(nil)
+  end
+
+  def test_url_decode
+    assert_equal 'foo bar', @filters.url_decode('foo+bar')
+    assert_equal 'foo bar', @filters.url_decode('foo%20bar')
+    assert_equal 'foo+1@example.com', @filters.url_decode('foo%2B1%40example.com')
+    assert_equal '1', @filters.url_decode(1)
+    assert_equal '2001-02-03', @filters.url_decode(Date.new(2001, 2, 3))
+    assert_nil @filters.url_decode(nil)
+    exception = assert_raises Liquid::ArgumentError do
+      @filters.url_decode('%ff')
+    end
+    assert_equal 'Liquid error: invalid byte sequence in UTF-8', exception.message
+  end
+
   def test_truncatewords
     assert_equal 'one two three', @filters.truncatewords('one two three', 4)
     assert_equal 'one two...', @filters.truncatewords('one two three', 2)
     assert_equal 'one two three', @filters.truncatewords('one two three')
     assert_equal 'Two small (13&#8221; x 5.5&#8221; x 10&#8221; high) baskets fit inside one large basket (13&#8221;...', @filters.truncatewords('Two small (13&#8221; x 5.5&#8221; x 10&#8221; high) baskets fit inside one large basket (13&#8221; x 16&#8221; x 10.5&#8221; high) with cover.', 15)
-    assert_equal "测试测试测试测试", @filters.truncatewords('测试测试测试测试', 5)
+    assert_equal '测试测试测试测试', @filters.truncatewords('测试测试测试测试', 5)
+    assert_equal 'one two1', @filters.truncatewords('one two three', 2, 1)
   end
 
   def test_strip_html
-    assert_equal 'test', @filters.strip_html("<div>test</div>")
+    assert_equal 'test', @filters.strip_html('<div>test</div>')
     assert_equal 'test', @filters.strip_html("<div id='test'>test</div>")
     assert_equal '', @filters.strip_html("<script type='text/javascript'>document.write('some stuff');</script>")
     assert_equal '', @filters.strip_html("<style type='text/css'>foo bar</style>")
     assert_equal 'test', @filters.strip_html("<div\nclass='multiline'>test</div>")
     assert_equal 'test', @filters.strip_html("<!-- foo bar \n test -->test")
     assert_equal '', @filters.strip_html(nil)
+
+    # Quirk of the existing implementation
+    assert_equal 'foo;', @filters.strip_html('<<<script </script>script>foo;</script>')
   end
 
   def test_join
-    assert_equal '1 2 3 4', @filters.join([1,2,3,4])
-    assert_equal '1 - 2 - 3 - 4', @filters.join([1,2,3,4], ' - ')
+    assert_equal '1 2 3 4', @filters.join([1, 2, 3, 4])
+    assert_equal '1 - 2 - 3 - 4', @filters.join([1, 2, 3, 4], ' - ')
+    assert_equal '1121314', @filters.join([1, 2, 3, 4], 1)
   end
 
   def test_sort
-    assert_equal [1,2,3,4], @filters.sort([4,3,2,1])
-    assert_equal [{"a" => 1}, {"a" => 2}, {"a" => 3}, {"a" => 4}], @filters.sort([{"a" => 4}, {"a" => 3}, {"a" => 1}, {"a" => 2}], "a")
+    assert_equal [1, 2, 3, 4], @filters.sort([4, 3, 2, 1])
+    assert_equal [{ 'a' => 1 }, { 'a' => 2 }, { 'a' => 3 }, { 'a' => 4 }], @filters.sort([{ 'a' => 4 }, { 'a' => 3 }, { 'a' => 1 }, { 'a' => 2 }], 'a')
+  end
+
+  def test_sort_with_nils
+    assert_equal [1, 2, 3, 4, nil], @filters.sort([nil, 4, 3, 2, 1])
+    assert_equal [{ 'a' => 1 }, { 'a' => 2 }, { 'a' => 3 }, { 'a' => 4 }, {}], @filters.sort([{ 'a' => 4 }, { 'a' => 3 }, {}, { 'a' => 1 }, { 'a' => 2 }], 'a')
+  end
+
+  def test_sort_when_property_is_sometimes_missing_puts_nils_last
+    input = [
+      { 'price' => 4, 'handle' => 'alpha' },
+      { 'handle' => 'beta' },
+      { 'price' => 1, 'handle' => 'gamma' },
+      { 'handle' => 'delta' },
+      { 'price' => 2, 'handle' => 'epsilon' },
+    ]
+    expectation = [
+      { 'price' => 1, 'handle' => 'gamma' },
+      { 'price' => 2, 'handle' => 'epsilon' },
+      { 'price' => 4, 'handle' => 'alpha' },
+      { 'handle' => 'delta' },
+      { 'handle' => 'beta' },
+    ]
+    assert_equal expectation, @filters.sort(input, 'price')
+  end
+
+  def test_sort_natural
+    assert_equal %w[a B c D], @filters.sort_natural(%w[c D a B])
+    assert_equal [{ 'a' => 'a' }, { 'a' => 'B' }, { 'a' => 'c' }, { 'a' => 'D' }], @filters.sort_natural([{ 'a' => 'D' }, { 'a' => 'c' }, { 'a' => 'a' }, { 'a' => 'B' }], 'a')
+  end
+
+  def test_sort_natural_with_nils
+    assert_equal ['a', 'B', 'c', 'D', nil], @filters.sort_natural([nil, 'c', 'D', 'a', 'B'])
+    assert_equal [{ 'a' => 'a' }, { 'a' => 'B' }, { 'a' => 'c' }, { 'a' => 'D' }, {}], @filters.sort_natural([{ 'a' => 'D' }, { 'a' => 'c' }, {}, { 'a' => 'a' }, { 'a' => 'B' }], 'a')
+  end
+
+  def test_sort_natural_when_property_is_sometimes_missing_puts_nils_last
+    input = [
+      { 'price' => '4', 'handle' => 'alpha' },
+      { 'handle' => 'beta' },
+      { 'price' => '1', 'handle' => 'gamma' },
+      { 'handle' => 'delta' },
+      { 'price' => 2, 'handle' => 'epsilon' },
+    ]
+    expectation = [
+      { 'price' => '1', 'handle' => 'gamma' },
+      { 'price' => 2, 'handle' => 'epsilon' },
+      { 'price' => '4', 'handle' => 'alpha' },
+      { 'handle' => 'delta' },
+      { 'handle' => 'beta' },
+    ]
+    assert_equal expectation, @filters.sort_natural(input, 'price')
+  end
+
+  def test_sort_natural_case_check
+    input = [
+      { 'key' => 'X' },
+      { 'key' => 'Y' },
+      { 'key' => 'Z' },
+      { 'fake' => 't' },
+      { 'key' => 'a' },
+      { 'key' => 'b' },
+      { 'key' => 'c' },
+    ]
+    expectation = [
+      { 'key' => 'a' },
+      { 'key' => 'b' },
+      { 'key' => 'c' },
+      { 'key' => 'X' },
+      { 'key' => 'Y' },
+      { 'key' => 'Z' },
+      { 'fake' => 't' },
+    ]
+    assert_equal expectation, @filters.sort_natural(input, 'key')
+    assert_equal %w[a b c X Y Z], @filters.sort_natural(%w[X Y Z a b c])
+  end
+
+  def test_sort_empty_array
+    assert_equal [], @filters.sort([], 'a')
+  end
+
+  def test_sort_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3],
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.sort(foo, 'bar')
+    end
+  end
+
+  def test_sort_natural_empty_array
+    assert_equal [], @filters.sort_natural([], 'a')
+  end
+
+  def test_sort_natural_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3],
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.sort_natural(foo, 'bar')
+    end
   end
 
   def test_legacy_sort_hash
-    assert_equal [{a:1, b:2}], @filters.sort({a:1, b:2})
+    assert_equal [{ a: 1, b: 2 }], @filters.sort(a: 1, b: 2)
   end
 
   def test_numerical_vs_lexicographical_sort
     assert_equal [2, 10], @filters.sort([10, 2])
-    assert_equal [{"a" => 2}, {"a" => 10}], @filters.sort([{"a" => 10}, {"a" => 2}], "a")
-    assert_equal ["10", "2"], @filters.sort(["10", "2"])
-    assert_equal [{"a" => "10"}, {"a" => "2"}], @filters.sort([{"a" => "10"}, {"a" => "2"}], "a")
+    assert_equal [{ 'a' => 2 }, { 'a' => 10 }], @filters.sort([{ 'a' => 10 }, { 'a' => 2 }], 'a')
+    assert_equal %w[10 2], @filters.sort(%w[10 2])
+    assert_equal [{ 'a' => '10' }, { 'a' => '2' }], @filters.sort([{ 'a' => '10' }, { 'a' => '2' }], 'a')
+  end
+
+  def test_uniq
+    assert_equal ['foo'], @filters.uniq('foo')
+    assert_equal [1, 3, 2, 4], @filters.uniq([1, 1, 3, 2, 3, 1, 4, 3, 2, 1])
+    assert_equal [{ 'a' => 1 }, { 'a' => 3 }, { 'a' => 2 }], @filters.uniq([{ 'a' => 1 }, { 'a' => 3 }, { 'a' => 1 }, { 'a' => 2 }], 'a')
+    testdrop = TestDrop.new
+    assert_equal [testdrop], @filters.uniq([testdrop, TestDrop.new], 'test')
+  end
+
+  def test_uniq_empty_array
+    assert_equal [], @filters.uniq([], 'a')
+  end
+
+  def test_uniq_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3],
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.uniq(foo, 'bar')
+    end
+  end
+
+  def test_compact_empty_array
+    assert_equal [], @filters.compact([], 'a')
+  end
+
+  def test_compact_invalid_property
+    foo = [
+      [1],
+      [2],
+      [3],
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.compact(foo, 'bar')
+    end
   end
 
   def test_reverse
-    assert_equal [4,3,2,1], @filters.reverse([1,2,3,4])
+    assert_equal [4, 3, 2, 1], @filters.reverse([1, 2, 3, 4])
   end
 
   def test_legacy_reverse_hash
-    assert_equal [{a:1, b:2}], @filters.reverse(a:1, b:2)
+    assert_equal [{ a: 1, b: 2 }], @filters.reverse(a: 1, b: 2)
   end
 
   def test_map
-    assert_equal [1,2,3,4], @filters.map([{"a" => 1}, {"a" => 2}, {"a" => 3}, {"a" => 4}], 'a')
+    assert_equal [1, 2, 3, 4], @filters.map([{ 'a' => 1 }, { 'a' => 2 }, { 'a' => 3 }, { 'a' => 4 }], 'a')
     assert_template_result 'abc', "{{ ary | map:'foo' | map:'bar' }}",
-      'ary' => [{'foo' => {'bar' => 'a'}}, {'foo' => {'bar' => 'b'}}, {'foo' => {'bar' => 'c'}}]
+                           'ary' => [{ 'foo' => { 'bar' => 'a' } }, { 'foo' => { 'bar' => 'b' } }, { 'foo' => { 'bar' => 'c' } }]
   end
 
   def test_map_doesnt_call_arbitrary_stuff
-    assert_template_result "", '{{ "foo" | map: "__id__" }}'
-    assert_template_result "", '{{ "foo" | map: "inspect" }}'
+    assert_template_result '', '{{ "foo" | map: "__id__" }}'
+    assert_template_result '', '{{ "foo" | map: "inspect" }}'
   end
 
   def test_map_calls_to_liquid
     t = TestThing.new
-    assert_template_result "woot: 1", '{{ foo | map: "whatever" }}', "foo" => [t]
+    assert_template_result 'woot: 1', '{{ foo | map: "whatever" }}', 'foo' => [t]
   end
 
   def test_map_on_hashes
-    assert_template_result "4217", '{{ thing | map: "foo" | map: "bar" }}',
-      "thing" => { "foo" => [ { "bar" => 42 }, { "bar" => 17 } ] }
+    assert_template_result '4217', '{{ thing | map: "foo" | map: "bar" }}',
+                           'thing' => { 'foo' => [{ 'bar' => 42 }, { 'bar' => 17 }] }
   end
 
   def test_legacy_map_on_hashes_with_dynamic_key
     template = "{% assign key = 'foo' %}{{ thing | map: key | map: 'bar' }}"
-    hash = { "foo" => { "bar" => 42 } }
-    assert_template_result "42", template, "thing" => hash
+    hash = { 'foo' => { 'bar' => 42 } }
+    assert_template_result '42', template, 'thing' => hash
   end
 
   def test_sort_calls_to_liquid
     t = TestThing.new
-    Liquid::Template.parse('{{ foo | sort: "whatever" }}').render("foo" => [t])
-    assert t.foo > 0
+    Liquid::Template.parse('{{ foo | sort: "whatever" }}').render('foo' => [t])
+    assert t.foo.positive?
   end
 
   def test_map_over_proc
     drop = TestDrop.new
-    p = Proc.new{ drop }
+    p = proc { drop }
     templ = '{{ procs | map: "test" }}'
-    assert_template_result "testfoo", templ, "procs" => [p]
+    assert_template_result 'testfoo', templ, 'procs' => [p]
+  end
+
+  def test_map_over_drops_returning_procs
+    drops = [
+      {
+        'proc' => -> { 'foo' },
+      },
+      {
+        'proc' => -> { 'bar' },
+      },
+    ]
+    templ = '{{ drops | map: "proc" }}'
+    assert_template_result 'foobar', templ, 'drops' => drops
   end
 
   def test_map_works_on_enumerables
-    assert_template_result "123", '{{ foo | map: "foo" }}', "foo" => TestEnumerable.new
+    assert_template_result '123', '{{ foo | map: "foo" }}', 'foo' => TestEnumerable.new
+  end
+
+  def test_map_returns_empty_on_2d_input_array
+    foo = [
+      [1],
+      [2],
+      [3],
+    ]
+
+    assert_raises Liquid::ArgumentError do
+      @filters.map(foo, 'bar')
+    end
+  end
+
+  def test_map_returns_empty_with_no_property
+    foo = [
+      [1],
+      [2],
+      [3],
+    ]
+    assert_raises Liquid::ArgumentError do
+      @filters.map(foo, nil)
+    end
   end
 
   def test_sort_works_on_enumerables
-    assert_template_result "213", '{{ foo | sort: "bar" | map: "foo" }}', "foo" => TestEnumerable.new
+    assert_template_result '213', '{{ foo | sort: "bar" | map: "foo" }}', 'foo' => TestEnumerable.new
+  end
+
+  def test_first_and_last_call_to_liquid
+    assert_template_result 'foobar', '{{ foo | first }}', 'foo' => [ThingWithToLiquid.new]
+    assert_template_result 'foobar', '{{ foo | last }}', 'foo' => [ThingWithToLiquid.new]
+  end
+
+  def test_truncate_calls_to_liquid
+    assert_template_result 'wo...', '{{ foo | truncate: 5 }}', 'foo' => TestThing.new
   end
 
   def test_date
-    assert_equal 'May', @filters.date(Time.parse("2006-05-05 10:00:00"), "%B")
-    assert_equal 'June', @filters.date(Time.parse("2006-06-05 10:00:00"), "%B")
-    assert_equal 'July', @filters.date(Time.parse("2006-07-05 10:00:00"), "%B")
+    assert_equal 'May', @filters.date(Time.parse('2006-05-05 10:00:00'), '%B')
+    assert_equal 'June', @filters.date(Time.parse('2006-06-05 10:00:00'), '%B')
+    assert_equal 'July', @filters.date(Time.parse('2006-07-05 10:00:00'), '%B')
 
-    assert_equal 'May', @filters.date("2006-05-05 10:00:00", "%B")
-    assert_equal 'June', @filters.date("2006-06-05 10:00:00", "%B")
-    assert_equal 'July', @filters.date("2006-07-05 10:00:00", "%B")
+    assert_equal 'May', @filters.date('2006-05-05 10:00:00', '%B')
+    assert_equal 'June', @filters.date('2006-06-05 10:00:00', '%B')
+    assert_equal 'July', @filters.date('2006-07-05 10:00:00', '%B')
 
-    assert_equal '2006-07-05 10:00:00', @filters.date("2006-07-05 10:00:00", "")
-    assert_equal '2006-07-05 10:00:00', @filters.date("2006-07-05 10:00:00", "")
-    assert_equal '2006-07-05 10:00:00', @filters.date("2006-07-05 10:00:00", "")
-    assert_equal '2006-07-05 10:00:00', @filters.date("2006-07-05 10:00:00", nil)
+    assert_equal '2006-07-05 10:00:00', @filters.date('2006-07-05 10:00:00', '')
+    assert_equal '2006-07-05 10:00:00', @filters.date('2006-07-05 10:00:00', '')
+    assert_equal '2006-07-05 10:00:00', @filters.date('2006-07-05 10:00:00', '')
+    assert_equal '2006-07-05 10:00:00', @filters.date('2006-07-05 10:00:00', nil)
 
-    assert_equal '07/05/2006', @filters.date("2006-07-05 10:00:00", "%m/%d/%Y")
+    assert_equal '07/05/2006', @filters.date('2006-07-05 10:00:00', '%m/%d/%Y')
 
-    assert_equal "07/16/2004", @filters.date("Fri Jul 16 01:00:00 2004", "%m/%d/%Y")
-    assert_equal "#{Date.today.year}", @filters.date('now', '%Y')
-    assert_equal "#{Date.today.year}", @filters.date('today', '%Y')
+    assert_equal '07/16/2004', @filters.date('Fri Jul 16 01:00:00 2004', '%m/%d/%Y')
+    assert_equal Date.today.year.to_s, @filters.date('now', '%Y')
+    assert_equal Date.today.year.to_s, @filters.date('today', '%Y')
+    assert_equal Date.today.year.to_s, @filters.date('Today', '%Y')
 
-    assert_equal nil, @filters.date(nil, "%B")
+    assert_nil @filters.date(nil, '%B')
 
-    assert_equal "07/05/2006", @filters.date(1152098955, "%m/%d/%Y")
-    assert_equal "07/05/2006", @filters.date("1152098955", "%m/%d/%Y")
+    assert_equal '', @filters.date('', '%B')
+
+    with_timezone('UTC') do
+      assert_equal '07/05/2006', @filters.date(1_152_098_955, '%m/%d/%Y')
+      assert_equal '07/05/2006', @filters.date('1152098955', '%m/%d/%Y')
+    end
   end
 
   def test_first_last
-    assert_equal 1, @filters.first([1,2,3])
-    assert_equal 3, @filters.last([1,2,3])
-    assert_equal nil, @filters.first([])
-    assert_equal nil, @filters.last([])
+    assert_equal 1, @filters.first([1, 2, 3])
+    assert_equal 3, @filters.last([1, 2, 3])
+    assert_nil @filters.first([])
+    assert_nil @filters.last([])
   end
 
   def test_replace
     assert_equal '2 2 2 2', @filters.replace('1 1 1 1', '1', 2)
+    assert_equal '2 2 2 2', @filters.replace('1 1 1 1', 1, 2)
     assert_equal '2 1 1 1', @filters.replace_first('1 1 1 1', '1', 2)
+    assert_equal '2 1 1 1', @filters.replace_first('1 1 1 1', 1, 2)
     assert_template_result '2 1 1 1', "{{ '1 1 1 1' | replace_first: '1', 2 }}"
   end
 
   def test_remove
-    assert_equal '   ', @filters.remove("a a a a", 'a')
-    assert_equal 'a a a', @filters.remove_first("a a a a", 'a ')
+    assert_equal '   ', @filters.remove('a a a a', 'a')
+    assert_equal '   ', @filters.remove('1 1 1 1', 1)
+    assert_equal 'a a a', @filters.remove_first('a a a a', 'a ')
+    assert_equal ' 1 1 1', @filters.remove_first('1 1 1 1', 1)
     assert_template_result 'a a a', "{{ 'a a a a' | remove_first: 'a ' }}"
   end
 
@@ -234,100 +514,263 @@ class StandardFiltersTest < Test::Unit::TestCase
   end
 
   def test_strip
-    assert_template_result 'ab c', "{{ source | strip }}", 'source' => " ab c  "
-    assert_template_result 'ab c', "{{ source | strip }}", 'source' => " \tab c  \n \t"
+    assert_template_result 'ab c', '{{ source | strip }}', 'source' => ' ab c  '
+    assert_template_result 'ab c', '{{ source | strip }}', 'source' => " \tab c  \n \t"
   end
 
   def test_lstrip
-    assert_template_result 'ab c  ', "{{ source | lstrip }}", 'source' => " ab c  "
-    assert_template_result "ab c  \n \t", "{{ source | lstrip }}", 'source' => " \tab c  \n \t"
+    assert_template_result 'ab c  ', '{{ source | lstrip }}', 'source' => ' ab c  '
+    assert_template_result "ab c  \n \t", '{{ source | lstrip }}', 'source' => " \tab c  \n \t"
   end
 
   def test_rstrip
-    assert_template_result " ab c", "{{ source | rstrip }}", 'source' => " ab c  "
-    assert_template_result " \tab c", "{{ source | rstrip }}", 'source' => " \tab c  \n \t"
+    assert_template_result ' ab c', '{{ source | rstrip }}', 'source' => ' ab c  '
+    assert_template_result " \tab c", '{{ source | rstrip }}', 'source' => " \tab c  \n \t"
   end
 
   def test_strip_newlines
-    assert_template_result 'abc', "{{ source | strip_newlines }}", 'source' => "a\nb\nc"
-    assert_template_result 'abc', "{{ source | strip_newlines }}", 'source' => "a\r\nb\nc"
+    assert_template_result 'abc', '{{ source | strip_newlines }}', 'source' => "a\nb\nc"
+    assert_template_result 'abc', '{{ source | strip_newlines }}', 'source' => "a\r\nb\nc"
   end
 
   def test_newlines_to_br
-    assert_template_result "a<br />\nb<br />\nc", "{{ source | newline_to_br }}", 'source' => "a\nb\nc"
+    assert_template_result "a<br />\nb<br />\nc", '{{ source | newline_to_br }}', 'source' => "a\nb\nc"
   end
 
   def test_plus
-    assert_template_result "2", "{{ 1 | plus:1 }}"
-    assert_template_result "2.0", "{{ '1' | plus:'1.0' }}"
+    assert_template_result '2', '{{ 1 | plus:1 }}'
+    assert_template_result '2.0', "{{ '1' | plus:'1.0' }}"
+
+    assert_template_result '5', "{{ price | plus:'2' }}", 'price' => NumberLikeThing.new(3)
   end
 
   def test_minus
-    assert_template_result "4", "{{ input | minus:operand }}", 'input' => 5, 'operand' => 1
-    assert_template_result "2.3", "{{ '4.3' | minus:'2' }}"
+    assert_template_result '4', '{{ input | minus:operand }}', 'input' => 5, 'operand' => 1
+    assert_template_result '2.3', "{{ '4.3' | minus:'2' }}"
+
+    assert_template_result '5', "{{ price | minus:'2' }}", 'price' => NumberLikeThing.new(7)
+  end
+
+  def test_abs
+    assert_template_result '17', '{{ 17 | abs }}'
+    assert_template_result '17', '{{ -17 | abs }}'
+    assert_template_result '17', "{{ '17' | abs }}"
+    assert_template_result '17', "{{ '-17' | abs }}"
+    assert_template_result '0', '{{ 0 | abs }}'
+    assert_template_result '0', "{{ '0' | abs }}"
+    assert_template_result '17.42', '{{ 17.42 | abs }}'
+    assert_template_result '17.42', '{{ -17.42 | abs }}'
+    assert_template_result '17.42', "{{ '17.42' | abs }}"
+    assert_template_result '17.42', "{{ '-17.42' | abs }}"
   end
 
   def test_times
-    assert_template_result "12", "{{ 3 | times:4 }}"
-    assert_template_result "0", "{{ 'foo' | times:4 }}"
-
-    assert_template_result "6", "{{ '2.1' | times:3 | replace: '.','-' | plus:0}}"
-
-    assert_template_result "7.25", "{{ 0.0725 | times:100 }}"
+    assert_template_result '12', '{{ 3 | times:4 }}'
+    assert_template_result '0', "{{ 'foo' | times:4 }}"
+    assert_template_result '6', "{{ '2.1' | times:3 | replace: '.','-' | plus:0}}"
+    assert_template_result '7.25', '{{ 0.0725 | times:100 }}'
+    assert_template_result '-7.25', '{{ "-0.0725" | times:100 }}'
+    assert_template_result '7.25', '{{ "-0.0725" | times: -100 }}'
+    assert_template_result '4', '{{ price | times:2 }}', 'price' => NumberLikeThing.new(2)
   end
 
   def test_divided_by
-    assert_template_result "4", "{{ 12 | divided_by:3 }}"
-    assert_template_result "4", "{{ 14 | divided_by:3 }}"
+    assert_template_result '4', '{{ 12 | divided_by:3 }}'
+    assert_template_result '4', '{{ 14 | divided_by:3 }}'
 
-    assert_template_result "5", "{{ 15 | divided_by:3 }}"
-    assert_equal "Liquid error: divided by 0", Template.parse("{{ 5 | divided_by:0 }}").render
+    assert_template_result '5', '{{ 15 | divided_by:3 }}'
+    assert_equal 'Liquid error: divided by 0', Template.parse('{{ 5 | divided_by:0 }}').render
 
-    assert_template_result "0.5", "{{ 2.0 | divided_by:4 }}"
+    assert_template_result '0.5', '{{ 2.0 | divided_by:4 }}'
+    assert_raises(Liquid::ZeroDivisionError) do
+      assert_template_result '4', '{{ 1 | modulo: 0 }}'
+    end
+
+    assert_template_result '5', '{{ price | divided_by:2 }}', 'price' => NumberLikeThing.new(10)
   end
 
   def test_modulo
-    assert_template_result "1", "{{ 3 | modulo:2 }}"
+    assert_template_result '1', '{{ 3 | modulo:2 }}'
+    assert_raises(Liquid::ZeroDivisionError) do
+      assert_template_result '4', '{{ 1 | modulo: 0 }}'
+    end
+
+    assert_template_result '1', '{{ price | modulo:2 }}', 'price' => NumberLikeThing.new(3)
   end
 
   def test_round
-    assert_template_result "5", "{{ input | round }}", 'input' => 4.6
-    assert_template_result "4", "{{ '4.3' | round }}"
-    assert_template_result "4.56", "{{ input | round: 2 }}", 'input' => 4.5612
+    assert_template_result '5', '{{ input | round }}', 'input' => 4.6
+    assert_template_result '4', "{{ '4.3' | round }}"
+    assert_template_result '4.56', '{{ input | round: 2 }}', 'input' => 4.5612
+    assert_raises(Liquid::FloatDomainError) do
+      assert_template_result '4', '{{ 1.0 | divided_by: 0.0 | round }}'
+    end
+
+    assert_template_result '5', '{{ price | round }}', 'price' => NumberLikeThing.new(4.6)
+    assert_template_result '4', '{{ price | round }}', 'price' => NumberLikeThing.new(4.3)
   end
 
   def test_ceil
-    assert_template_result "5", "{{ input | ceil }}", 'input' => 4.6
-    assert_template_result "5", "{{ '4.3' | ceil }}"
+    assert_template_result '5', '{{ input | ceil }}', 'input' => 4.6
+    assert_template_result '5', "{{ '4.3' | ceil }}"
+    assert_raises(Liquid::FloatDomainError) do
+      assert_template_result '4', '{{ 1.0 | divided_by: 0.0 | ceil }}'
+    end
+
+    assert_template_result '5', '{{ price | ceil }}', 'price' => NumberLikeThing.new(4.6)
   end
 
   def test_floor
-    assert_template_result "4", "{{ input | floor }}", 'input' => 4.6
-    assert_template_result "4", "{{ '4.3' | floor }}"
+    assert_template_result '4', '{{ input | floor }}', 'input' => 4.6
+    assert_template_result '4', "{{ '4.3' | floor }}"
+    assert_raises(Liquid::FloatDomainError) do
+      assert_template_result '4', '{{ 1.0 | divided_by: 0.0 | floor }}'
+    end
+
+    assert_template_result '5', '{{ price | floor }}', 'price' => NumberLikeThing.new(5.4)
+  end
+
+  def test_at_most
+    assert_template_result '4', '{{ 5 | at_most:4 }}'
+    assert_template_result '5', '{{ 5 | at_most:5 }}'
+    assert_template_result '5', '{{ 5 | at_most:6 }}'
+
+    assert_template_result '4.5', '{{ 4.5 | at_most:5 }}'
+    assert_template_result '5', '{{ width | at_most:5 }}', 'width' => NumberLikeThing.new(6)
+    assert_template_result '4', '{{ width | at_most:5 }}', 'width' => NumberLikeThing.new(4)
+    assert_template_result '4', '{{ 5 | at_most: width }}', 'width' => NumberLikeThing.new(4)
+  end
+
+  def test_at_least
+    assert_template_result '5', '{{ 5 | at_least:4 }}'
+    assert_template_result '5', '{{ 5 | at_least:5 }}'
+    assert_template_result '6', '{{ 5 | at_least:6 }}'
+
+    assert_template_result '5', '{{ 4.5 | at_least:5 }}'
+    assert_template_result '6', '{{ width | at_least:5 }}', 'width' => NumberLikeThing.new(6)
+    assert_template_result '5', '{{ width | at_least:5 }}', 'width' => NumberLikeThing.new(4)
+    assert_template_result '6', '{{ 5 | at_least: width }}', 'width' => NumberLikeThing.new(6)
   end
 
   def test_append
-    assigns = {'a' => 'bc', 'b' => 'd' }
-    assert_template_result('bcd',"{{ a | append: 'd'}}",assigns)
-    assert_template_result('bcd',"{{ a | append: b}}",assigns)
+    assigns = { 'a' => 'bc', 'b' => 'd' }
+    assert_template_result('bcd', "{{ a | append: 'd'}}", assigns)
+    assert_template_result('bcd', '{{ a | append: b}}', assigns)
+  end
+
+  def test_concat
+    assert_equal [1, 2, 3, 4], @filters.concat([1, 2], [3, 4])
+    assert_equal [1, 2, 'a'],  @filters.concat([1, 2], ['a'])
+    assert_equal [1, 2, 10],   @filters.concat([1, 2], [10])
+
+    assert_raises(Liquid::ArgumentError, 'concat filter requires an array argument') do
+      @filters.concat([1, 2], 10)
+    end
   end
 
   def test_prepend
-    assigns = {'a' => 'bc', 'b' => 'a' }
-    assert_template_result('abc',"{{ a | prepend: 'a'}}",assigns)
-    assert_template_result('abc',"{{ a | prepend: b}}",assigns)
+    assigns = { 'a' => 'bc', 'b' => 'a' }
+    assert_template_result('abc', "{{ a | prepend: 'a'}}", assigns)
+    assert_template_result('abc', '{{ a | prepend: b}}', assigns)
   end
 
   def test_default
-    assert_equal "foo", @filters.default("foo", "bar")
-    assert_equal "bar", @filters.default(nil, "bar")
-    assert_equal "bar", @filters.default("", "bar")
-    assert_equal "bar", @filters.default(false, "bar")
-    assert_equal "bar", @filters.default([], "bar")
-    assert_equal "bar", @filters.default({}, "bar")
+    assert_equal 'foo', @filters.default('foo', 'bar')
+    assert_equal 'bar', @filters.default(nil, 'bar')
+    assert_equal 'bar', @filters.default('', 'bar')
+    assert_equal 'bar', @filters.default(false, 'bar')
+    assert_equal 'bar', @filters.default([], 'bar')
+    assert_equal 'bar', @filters.default({}, 'bar')
   end
 
   def test_cannot_access_private_methods
-    assert_template_result('a',"{{ 'a' | to_number }}")
+    assert_template_result('a', "{{ 'a' | to_number }}")
+  end
+
+  def test_date_raises_nothing
+    assert_template_result('', "{{ '' | date: '%D' }}")
+    assert_template_result('abc', "{{ 'abc' | date: '%D' }}")
+  end
+
+  def test_where
+    input = [
+      { 'handle' => 'alpha', 'ok' => true },
+      { 'handle' => 'beta', 'ok' => false },
+      { 'handle' => 'gamma', 'ok' => false },
+      { 'handle' => 'delta', 'ok' => true },
+    ]
+
+    expectation = [
+      { 'handle' => 'alpha', 'ok' => true },
+      { 'handle' => 'delta', 'ok' => true },
+    ]
+
+    assert_equal expectation, @filters.where(input, 'ok', true)
+    assert_equal expectation, @filters.where(input, 'ok')
+  end
+
+  def test_where_no_key_set
+    input = [
+      { 'handle' => 'alpha', 'ok' => true },
+      { 'handle' => 'beta' },
+      { 'handle' => 'gamma' },
+      { 'handle' => 'delta', 'ok' => true },
+    ]
+
+    expectation = [
+      { 'handle' => 'alpha', 'ok' => true },
+      { 'handle' => 'delta', 'ok' => true },
+    ]
+
+    assert_equal expectation, @filters.where(input, 'ok', true)
+    assert_equal expectation, @filters.where(input, 'ok')
+  end
+
+  def test_where_non_array_map_input
+    assert_equal [{ 'a' => 'ok' }], @filters.where({ 'a' => 'ok' }, 'a', 'ok')
+    assert_equal [], @filters.where({ 'a' => 'not ok' }, 'a', 'ok')
+  end
+
+  def test_where_indexable_but_non_map_value
+    assert_raises(Liquid::ArgumentError) { @filters.where(1, 'ok', true) }
+    assert_raises(Liquid::ArgumentError) { @filters.where(1, 'ok') }
+  end
+
+  def test_where_non_boolean_value
+    input = [
+      { 'message' => 'Bonjour!', 'language' => 'French' },
+      { 'message' => 'Hello!', 'language' => 'English' },
+      { 'message' => 'Hallo!', 'language' => 'German' },
+    ]
+
+    assert_equal [{ 'message' => 'Bonjour!', 'language' => 'French' }], @filters.where(input, 'language', 'French')
+    assert_equal [{ 'message' => 'Hallo!', 'language' => 'German' }], @filters.where(input, 'language', 'German')
+    assert_equal [{ 'message' => 'Hello!', 'language' => 'English' }], @filters.where(input, 'language', 'English')
+  end
+
+  def test_where_array_of_only_unindexable_values
+    assert_nil @filters.where([nil], 'ok', true)
+    assert_nil @filters.where([nil], 'ok')
+  end
+
+  def test_where_no_target_value
+    input = [
+      { 'foo' => false },
+      { 'foo' => true },
+      { 'foo' => 'for sure' },
+      { 'bar' => true },
+    ]
+
+    assert_equal [{ 'foo' => true }, { 'foo' => 'for sure' }], @filters.where(input, 'foo')
+  end
+
+  private
+
+  def with_timezone(tz)
+    old_tz = ENV['TZ']
+    ENV['TZ'] = tz
+    yield
+  ensure
+    ENV['TZ'] = old_tz
   end
 end # StandardFiltersTest

test/integration/tags/break_tag_test.rb

@@ -1,16 +1,17 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-class BreakTagTest < Test::Unit::TestCase
+class BreakTagTest < Minitest::Test
   include Liquid
 
   # tests that no weird errors are raised if break is called outside of a
   # block
   def test_break_with_no_block
-    assigns = {'i' => 1}
+    assigns = { 'i' => 1 }
     markup = '{% break %}'
     expected = ''
 
     assert_template_result(expected, markup, assigns)
   end
-
 end

test/integration/tags/continue_tag_test.rb

@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
-class ContinueTagTest < Test::Unit::TestCase
+class ContinueTagTest < Minitest::Test
   include Liquid
 
   # tests that no weird errors are raised if continue is called outside of a
@@ -12,5 +14,4 @@ class ContinueTagTest < Test::Unit::TestCase
 
     assert_template_result(expected, markup, assigns)
   end
-
 end