v4.0.2

Validate the character encoding in url_decode.

.github/probots.yml

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

.rubocop.yml

@@ -7,8 +7,6 @@ AllCops:
 
 Metrics/BlockNesting:
   Max: 3
-  Exclude:
-    - 'lib/liquid/block_body.rb'
 
 Metrics/ModuleLength:
   Enabled: false
@@ -32,7 +30,7 @@ Lint/UnusedBlockArgument:
   Enabled: false
 
 Lint/EndAlignment:
-  AlignWith: variable
+  EnforcedStyleAlignWith: variable
 
 Lint/UnusedMethodArgument:
   Enabled: false
@@ -61,10 +59,10 @@ Style/BracesAroundHashParameters:
 Style/NumericLiterals:
   Enabled: false
 
-Style/SpaceInsideBrackets:
+Layout/SpaceInsideBrackets:
   Enabled: false
 
-Style/SpaceBeforeBlockBraces:
+Layout/SpaceBeforeBlockBraces:
   Enabled: false
 
 Style/Documentation:
@@ -73,19 +71,19 @@ Style/Documentation:
 Style/ClassAndModuleChildren:
   Enabled: false
 
-Style/TrailingComma:
+Style/TrailingCommaInLiteral:
   Enabled: false
 
-Style/IndentHash:
+Layout/IndentHash:
   EnforcedStyle: consistent
 
 Style/FormatString:
   Enabled: false
 
-Style/AlignParameters:
+Layout/AlignParameters:
   EnforcedStyle: with_fixed_indentation
 
-Style/MultilineOperationIndentation:
+Layout/MultilineOperationIndentation:
   EnforcedStyle: indented
 
 Style/IfUnlessModifier:
@@ -94,7 +92,7 @@ Style/IfUnlessModifier:
 Style/RaiseArgs:
   Enabled: false
 
-Style/DeprecatedHashMethods:
+Style/PreferredHashMethods:
   Enabled: false
 
 Style/RegexpLiteral:
@@ -109,7 +107,7 @@ Performance/Count:
 Style/ConstantName:
   Enabled: false
 
-Style/CaseIndentation:
+Layout/CaseIndentation:
   Enabled: false
 
 Style/ClassVars:
@@ -123,3 +121,7 @@ Style/TrivialAccessors:
 
 Style/WordArray:
   Enabled: false
+
+Style/MethodName:
+  Exclude:
+    - 'example/server/liquid_servlet.rb'

.rubocop_todo.yml

@@ -1,72 +1,194 @@
-# This configuration was generated by `rubocop --auto-gen-config`
-# on 2015-06-08 18:16:16 +0000 using RuboCop version 0.32.0.
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2019-02-03 21:12:39 +0530 using RuboCop version 0.49.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
 # Offense count: 5
-Lint/NestedMethodDefinition:
-  Enabled: false
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, SupportedStyles.
+# SupportedStyles: auto_detection, squiggly, active_support, powerpack, unindent
+Layout/IndentHeredoc:
+  Exclude:
+    - 'test/integration/tags/for_tag_test.rb'
+    - 'test/integration/trim_mode_test.rb'
 
-# Offense count: 53
+# Offense count: 6
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, SupportedStyles.
+# SupportedStyles: symmetrical, new_line, same_line
+Layout/MultilineMethodCallBraceLayout:
+  Exclude:
+    - 'test/integration/error_handling_test.rb'
+    - 'test/unit/strainer_unit_test.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, SupportedStyles.
+# SupportedStyles: runtime_error, standard_error
+Lint/InheritException:
+  Exclude:
+    - 'lib/liquid/interrupts.rb'
+
+# Offense count: 51
 Metrics/AbcSize:
-  Max: 58
+  Max: 56
 
-# Offense count: 12
+# Offense count: 11
 Metrics/CyclomaticComplexity:
-  Max: 15
+  Max: 12
 
-# Offense count: 553
-# Configuration parameters: AllowURI, URISchemes.
+# Offense count: 639
+# Configuration parameters: AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
+# URISchemes: http, https
 Metrics/LineLength:
   Max: 294
 
-# Offense count: 77
+# Offense count: 108
 # Configuration parameters: CountComments.
 Metrics/MethodLength:
-  Max: 46
+  Max: 37
 
-# Offense count: 6
+# Offense count: 7
 Metrics/PerceivedComplexity:
-  Max: 13
+  Max: 11
 
-# Offense count: 1
-Style/AccessorMethodName:
-  Enabled: false
+# Offense count: 10
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, SupportedStyles.
+# SupportedStyles: prefer_alias, prefer_alias_method
+Style/Alias:
+  Exclude:
+    - 'lib/liquid/drop.rb'
+    - 'lib/liquid/i18n.rb'
+    - 'lib/liquid/profiler/hooks.rb'
+    - 'lib/liquid/standardfilters.rb'
+    - 'lib/liquid/tag.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'lib/liquid/variable.rb'
 
 # Offense count: 1
 # Cop supports --auto-correct.
-Style/ClosingParenthesisIndentation:
-  Enabled: false
-
-# Offense count: 3
-# Configuration parameters: MinBodyLength.
-Style/GuardClause:
-  Enabled: false
-
-# Offense count: 4
-# Configuration parameters: EnforcedStyle, SupportedStyles.
-Style/MethodName:
-  Enabled: false
-
-# Offense count: 1
-Style/MultilineBlockChain:
-  Enabled: false
+# Configuration parameters: EnforcedStyle, SupportedStyles, SingleLineConditionsOnly, IncludeTernaryExpressions.
+# SupportedStyles: assign_to_condition, assign_inside_condition
+Style/ConditionalAssignment:
+  Exclude:
+    - 'lib/liquid/errors.rb'
 
 # Offense count: 2
-# Configuration parameters: EnforcedStyle, MinBodyLength, SupportedStyles.
-Style/Next:
-  Enabled: false
+# Cop supports --auto-correct.
+Style/EmptyCaseCondition:
+  Exclude:
+    - 'lib/liquid/block_body.rb'
+    - 'lib/liquid/lexer.rb'
 
-# Offense count: 7
+# Offense count: 5
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, SupportedStyles.
+# SupportedStyles: compact, expanded
+Style/EmptyMethod:
+  Exclude:
+    - 'lib/liquid/tag.rb'
+    - 'lib/liquid/tags/comment.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'test/integration/tags/include_tag_test.rb'
+    - 'test/unit/context_unit_test.rb'
+
+# Offense count: 2
+# Configuration parameters: SupportedStyles.
+# SupportedStyles: annotated, template
+Style/FormatStringToken:
+  EnforcedStyle: template
+
+# Offense count: 14
+# Configuration parameters: MinBodyLength.
+Style/GuardClause:
+  Exclude:
+    - 'lib/liquid/condition.rb'
+    - 'lib/liquid/lexer.rb'
+    - 'lib/liquid/strainer.rb'
+    - 'lib/liquid/tags/assign.rb'
+    - 'lib/liquid/tags/capture.rb'
+    - 'lib/liquid/tags/case.rb'
+    - 'lib/liquid/tags/for.rb'
+    - 'lib/liquid/tags/include.rb'
+    - 'lib/liquid/tags/raw.rb'
+    - 'lib/liquid/tags/table_row.rb'
+    - 'lib/liquid/variable.rb'
+    - 'test/unit/tokenizer_unit_test.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, MinBodyLength, SupportedStyles.
+# SupportedStyles: skip_modifier_ifs, always
+Style/Next:
+  Exclude:
+    - 'lib/liquid/tags/for.rb'
+
+# Offense count: 4
+# Cop supports --auto-correct.
+# Configuration parameters: AutoCorrect, EnforcedStyle, SupportedStyles.
+# SupportedStyles: predicate, comparison
+Style/NumericPredicate:
+  Exclude:
+    - 'spec/**/*'
+    - 'lib/liquid/context.rb'
+    - 'lib/liquid/forloop_drop.rb'
+    - 'lib/liquid/standardfilters.rb'
+    - 'lib/liquid/tablerowloop_drop.rb'
+
+# Offense count: 14
+# Cop supports --auto-correct.
+# Configuration parameters: PreferredDelimiters.
+Style/PercentLiteralDelimiters:
+  Exclude:
+    - 'lib/liquid/tags/if.rb'
+    - 'liquid.gemspec'
+    - 'test/integration/assign_test.rb'
+    - 'test/integration/standard_filter_test.rb'
+
+# Offense count: 1
+# Cop supports --auto-correct.
+Style/RedundantSelf:
+  Exclude:
+    - 'lib/liquid/strainer.rb'
+
+# Offense count: 9
 # Cop supports --auto-correct.
 # Configuration parameters: AllowAsExpressionSeparator.
 Style/Semicolon:
-  Enabled: false
+  Exclude:
+    - 'test/integration/error_handling_test.rb'
+    - 'test/integration/template_test.rb'
+    - 'test/unit/context_unit_test.rb'
+
+# Offense count: 7
+# Cop supports --auto-correct.
+# Configuration parameters: MinSize, SupportedStyles.
+# SupportedStyles: percent, brackets
+Style/SymbolArray:
+  EnforcedStyle: brackets
+
+# Offense count: 2
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle, SupportedStyles, AllowSafeAssignment.
+# SupportedStyles: require_parentheses, require_no_parentheses, require_parentheses_when_complex
+Style/TernaryParentheses:
+  Exclude:
+    - 'lib/liquid/context.rb'
+    - 'lib/liquid/utils.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+Style/UnneededPercentQ:
+  Exclude:
+    - 'test/integration/error_handling_test.rb'
 
 # Offense count: 1
 # Cop supports --auto-correct.
 # Configuration parameters: MaxLineLength.
 Style/WhileUntilModifier:
-  Enabled: false
+  Exclude:
+    - 'lib/liquid/tags/case.rb'

.travis.yml

@@ -3,7 +3,9 @@ language: ruby
 rvm:
   - 2.1
   - 2.2
-  - 2.3.3
+  - 2.3
+  - 2.4
+  - 2.5
   - ruby-head
   - jruby-head
 #  - rbx-2
@@ -17,13 +19,14 @@ addons:
 
 matrix:
   allow_failures:
+    - rvm: ruby-head
     - rvm: jruby-head
 
 install:
   - gem install rainbow -v 2.2.1
   - bundle install
 
-script: "bundle exec rake"
+script: bundle exec rake
 
 notifications:
   disable: true

Gemfile

@@ -1,4 +1,7 @@
 source 'https://rubygems.org'
+git_source(:github) do |repo_name|
+  "https://github.com/#{repo_name}.git"
+end
 
 gemspec
 
@@ -9,9 +12,9 @@ group :benchmark, :test do
 end
 
 group :test do
-  gem 'rubocop', '0.34.2'
+  gem 'rubocop', '~> 0.49.0'
 
   platform :mri do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'bd53db95de3d44d631e7c5a267c3d934e66107dd'
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: '9168659de45d6d576fce30c735f857e597fa26f6'
   end
 end

History.md

@@ -1,5 +1,53 @@
 # Liquid Change Log
 
+## 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

README.md

@@ -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.
 

Rakefile

@@ -3,7 +3,7 @@ require 'rake/testtask'
 $LOAD_PATH.unshift File.expand_path("../lib", __FILE__)
 require "liquid/version"
 
-task default: [:rubocop, :test]
+task default: [:test, :rubocop]
 
 desc 'run test suite with default parser'
 Rake::TestTask.new(:base_test) do |t|

circle.yml

@@ -1,3 +0,0 @@
-machine:
-  ruby:
-    version: ruby-2.1

lib/liquid.rb

@@ -45,6 +45,7 @@ module Liquid
 end
 
 require "liquid/version"
+require 'liquid/parse_tree_visitor'
 require 'liquid/lexer'
 require 'liquid/parser'
 require 'liquid/i18n'

lib/liquid/block.rb

@@ -26,12 +26,12 @@ module Liquid
     end
 
     def unknown_tag(tag, _params, _tokens)
-      case tag
-      when 'else'.freeze
+      if tag == 'else'.freeze
         raise SyntaxError.new(parse_context.locale.t("errors.syntax.unexpected_else".freeze,
           block_name: block_name))
-      when 'end'.freeze
+      elsif tag.start_with?('end'.freeze)
         raise SyntaxError.new(parse_context.locale.t("errors.syntax.invalid_delimiter".freeze,
+          tag: tag,
           block_name: block_name,
           block_delimiter: block_delimiter))
       else

lib/liquid/block_body.rb

@@ -2,6 +2,7 @@ module Liquid
   class BlockBody
     FullToken = /\A#{TagStart}#{WhitespaceControl}?\s*(\w+)\s*(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
     ContentOfVariable = /\A#{VariableStart}#{WhitespaceControl}?(.*?)#{WhitespaceControl}?#{VariableEnd}\z/om
+    WhitespaceOrNothing = /\A\s*\z/
     TAGSTART = "{%".freeze
     VARSTART = "{{".freeze
 
@@ -15,38 +16,35 @@ module Liquid
     def parse(tokenizer, parse_context)
       parse_context.line_number = tokenizer.line_number
       while token = tokenizer.shift
-        unless token.empty?
-          case
-          when token.start_with?(TAGSTART)
-            whitespace_handler(token, parse_context)
-            if token =~ FullToken
-              tag_name = $1
-              markup = $2
-              # fetch the tag from registered blocks
-              if tag = registered_tags[tag_name]
-                new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
-                @blank &&= new_tag.blank?
-                @nodelist << new_tag
-              else
-                # end parsing if we reach an unknown tag and let the caller decide
-                # determine how to proceed
-                return yield tag_name, markup
-              end
-            else
-              raise_missing_tag_terminator(token, parse_context)
-            end
-          when token.start_with?(VARSTART)
-            whitespace_handler(token, parse_context)
-            @nodelist << create_variable(token, parse_context)
-            @blank = false
-          else
-            if parse_context.trim_whitespace
-              token.lstrip!
-            end
-            parse_context.trim_whitespace = false
-            @nodelist << token
-            @blank &&= !!(token =~ /\A\s*\z/)
+        next if token.empty?
+        case
+        when token.start_with?(TAGSTART)
+          whitespace_handler(token, parse_context)
+          unless token =~ FullToken
+            raise_missing_tag_terminator(token, parse_context)
           end
+          tag_name = $1
+          markup = $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?(VARSTART)
+          whitespace_handler(token, parse_context)
+          @nodelist << create_variable(token, parse_context)
+          @blank = false
+        else
+          if parse_context.trim_whitespace
+            token.lstrip!
+          end
+          parse_context.trim_whitespace = false
+          @nodelist << token
+          @blank &&= !!(token =~ WhitespaceOrNothing)
         end
         parse_context.line_number = tokenizer.line_number
       end
@@ -72,33 +70,27 @@ module Liquid
       output = []
       context.resource_limits.render_score += @nodelist.length
 
-      @nodelist.each do |token|
-        # Break out if we have any unhanded interrupts.
-        break if context.interrupt?
-
-        begin
+      idx = 0
+      while node = @nodelist[idx]
+        case node
+        when String
+          check_resources(context, node)
+          output << node
+        when Variable
+          render_node_to_output(node, output, context)
+        when Block
+          render_node_to_output(node, output, context, node.blank?)
+          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 %}
-          if token.is_a?(Continue) || token.is_a?(Break)
-            context.push_interrupt(token.interrupt)
-            break
-          end
-
-          node_output = render_node(token, context)
-
-          unless token.is_a?(Block) && token.blank?
-            output << node_output
-          end
-        rescue MemoryError => e
-          raise e
-        rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
-          context.handle_error(e, token.line_number)
-          output << nil
-        rescue ::StandardError => e
-          line_number = token.is_a?(String) ? nil : token.line_number
-          output << context.handle_error(e, line_number)
+          context.push_interrupt(node.interrupt)
+          break
+        else # Other non-Block tags
+          render_node_to_output(node, output, context)
         end
+        idx += 1
       end
 
       output.join
@@ -106,15 +98,25 @@ module Liquid
 
     private
 
-    def render_node(node, context)
-      node_output = node.is_a?(String) ? node : node.render(context)
+    def render_node_to_output(node, output, context, skip_output = false)
+      node_output = node.render(context)
       node_output = node_output.is_a?(Array) ? node_output.join : node_output.to_s
+      check_resources(context, node_output)
+      output << node_output unless skip_output
+    rescue MemoryError => e
+      raise e
+    rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
+      context.handle_error(e, node.line_number)
+      output << nil
+    rescue ::StandardError => e
+      line_number = node.is_a?(String) ? nil : node.line_number
+      output << context.handle_error(e, line_number)
+    end
 
+    def check_resources(context, node_output)
       context.resource_limits.render_length += node_output.length
-      if context.resource_limits.reached?
-        raise MemoryError.new("Memory limits exceeded".freeze)
-      end
-      node_output
+      return unless context.resource_limits.reached?
+      raise MemoryError.new("Memory limits exceeded".freeze)
     end
 
     def create_variable(token, parse_context)

lib/liquid/condition.rb

@@ -29,7 +29,7 @@ module Liquid
       @@operators
     end
 
-    attr_reader :attachment
+    attr_reader :attachment, :child_condition
     attr_accessor :left, :operator, :right
 
     def initialize(left = nil, operator = nil, right = nil)
@@ -83,7 +83,7 @@ module Liquid
 
     protected
 
-    attr_reader :child_relation, :child_condition
+    attr_reader :child_relation
 
     private
 
@@ -128,6 +128,15 @@ module Liquid
         end
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.left, @node.right,
+          @node.child_condition, @node.attachment
+        ].compact
+      end
+    end
   end
 
   class ElseCondition < Condition

lib/liquid/context.rb

@@ -171,7 +171,9 @@ module Liquid
       if scope.nil?
         @environments.each do |e|
           variable = lookup_and_evaluate(e, key, raise_on_not_found: raise_on_not_found)
-          unless variable.nil?
+          # 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

lib/liquid/expression.rb

@@ -19,22 +19,26 @@ module Liquid
       'false'.freeze => false,
       'blank'.freeze => MethodLiteral.new(:blank?, '').freeze,
       'empty'.freeze => MethodLiteral.new(:empty?, '').freeze
-    }
+    }.freeze
+
+    SINGLE_QUOTED_STRING = /\A'(.*)'\z/m
+    DOUBLE_QUOTED_STRING = /\A"(.*)"\z/m
+    INTEGERS_REGEX       = /\A(-?\d+)\z/
+    FLOATS_REGEX         = /\A(-?\d[\d\.]+)\z/
+    RANGES_REGEX         = /\A\((\S+)\.\.(\S+)\)\z/
 
     def self.parse(markup)
       if LITERALS.key?(markup)
         LITERALS[markup]
       else
         case markup
-        when /\A'(.*)'\z/m # Single quoted strings
+        when SINGLE_QUOTED_STRING, DOUBLE_QUOTED_STRING
           $1
-        when /\A"(.*)"\z/m # Double quoted strings
-          $1
-        when /\A(-?\d+)\z/ # Integer and floats
+        when INTEGERS_REGEX
           $1.to_i
-        when /\A\((\S+)\.\.(\S+)\)\z/ # Ranges
+        when RANGES_REGEX
           RangeLookup.parse($1, $2)
-        when /\A(-?\d[\d\.]+)\z/ # Floats
+        when FLOATS_REGEX
           $1.to_f
         else
           VariableLookup.parse(markup)

lib/liquid/extensions.rb

@@ -7,6 +7,12 @@ class String # :nodoc:
   end
 end
 
+class Symbol # :nodoc:
+  def to_liquid
+    to_s
+  end
+end
+
 class Array # :nodoc:
   def to_liquid
     self

lib/liquid/i18n.rb

@@ -26,7 +26,7 @@ module Liquid
     def interpolate(name, vars)
       name.gsub(/%\{(\w+)\}/) do
         # raise TranslationError, "Undefined key #{$1} for interpolation in translation #{name}"  unless vars[$1.to_sym]
-        "#{vars[$1.to_sym]}"
+        (vars[$1.to_sym]).to_s
       end
     end
 

lib/liquid/lexer.rb

@@ -12,13 +12,14 @@ module Liquid
       ')'.freeze => :close_round,
       '?'.freeze => :question,
       '-'.freeze => :dash
-    }
+    }.freeze
     IDENTIFIER = /[a-zA-Z_][\w-]*\??/
     SINGLE_STRING_LITERAL = /'[^\']*'/
     DOUBLE_STRING_LITERAL = /"[^\"]*"/
     NUMBER_LITERAL = /-?\d+(\.\d+)?/
     DOTDOT = /\.\./
     COMPARISON_OPERATOR = /==|!=|<>|<=?|>=?|contains(?=\s)/
+    WHITESPACE_OR_NOTHING = /\s*/
 
     def initialize(input)
       @ss = StringScanner.new(input)
@@ -28,7 +29,7 @@ module Liquid
       @output = []
 
       until @ss.eos?
-        @ss.skip(/\s*/)
+        @ss.skip(WHITESPACE_OR_NOTHING)
         break if @ss.eos?
         tok = case
         when t = @ss.scan(COMPARISON_OPERATOR) then [:comparison, t]

lib/liquid/locales/en.yml

@@ -14,7 +14,7 @@
       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}"
+      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}"

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/profiler/hooks.rb

@@ -1,13 +1,13 @@
 module Liquid
   class BlockBody
-    def render_node_with_profiling(node, context)
+    def render_node_with_profiling(node, output, context, skip_output = false)
       Profiler.profile_node_render(node) do
-        render_node_without_profiling(node, context)
+        render_node_without_profiling(node, output, context, skip_output)
       end
     end
 
-    alias_method :render_node_without_profiling, :render_node
-    alias_method :render_node, :render_node_with_profiling
+    alias_method :render_node_without_profiling, :render_node_to_output
+    alias_method :render_node_to_output, :render_node_with_profiling
   end
 
   class Include < Tag

lib/liquid/standardfilters.rb

@@ -9,8 +9,14 @@ module Liquid
       '<'.freeze => '&lt;'.freeze,
       '"'.freeze => '&quot;'.freeze,
       "'".freeze => '&#39;'.freeze
-    }
+    }.freeze
     HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+));)/
+    STRIP_HTML_BLOCKS = Regexp.union(
+      /<script.*?<\/script>/m,
+      /<!--.*?-->/m,
+      /<style.*?<\/style>/m
+    )
+    STRIP_HTML_TAGS = /<.*?>/m
 
     # Return the size of an array or of an string
     def size(input)
@@ -46,7 +52,12 @@ module Liquid
     end
 
     def url_decode(input)
-      CGI.unescape(input.to_s) unless input.nil?
+      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)
@@ -103,7 +114,9 @@ module Liquid
 
     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)
+      result = input.to_s.gsub(STRIP_HTML_BLOCKS, empty)
+      result.gsub!(STRIP_HTML_TAGS, empty)
+      result
     end
 
     # Remove all newlines from the string
@@ -120,19 +133,18 @@ 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.empty? # The next two cases assume a non-empty array.
-        []
-      elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
         ary.sort do |a, b|
-          a = a[property]
-          b = b[property]
-          if a && b
-            a <=> b
-          else
-            a ? -1 : 1
-          end
+          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
@@ -142,12 +154,40 @@ module Liquid
     def sort_natural(input, property = nil)
       ary = InputIterator.new(input)
 
+      return [] if ary.empty?
+
       if property.nil?
-        ary.sort { |a, b| a.casecmp(b) }
-      elsif ary.empty? # The next two cases assume a non-empty array.
+        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?(:[]) && !ary.first[property].nil?
-        ary.sort { |a, b| a[property].casecmp(b[property]) }
+      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
 
@@ -161,7 +201,11 @@ module Liquid
       elsif ary.empty? # The next two cases assume a non-empty array.
         []
       elsif ary.first.respond_to?(:[])
-        ary.uniq{ |a| a[property] }
+        begin
+          ary.uniq { |a| a[property] }
+        rescue TypeError
+          raise_property_error(property)
+        end
       end
     end
 
@@ -183,6 +227,8 @@ module Liquid
           r.is_a?(Proc) ? r.call : r
         end
       end
+    rescue TypeError
+      raise_property_error(property)
     end
 
     # Remove nils within an array
@@ -195,7 +241,11 @@ module Liquid
       elsif ary.empty? # The next two cases assume a non-empty array.
         []
       elsif ary.first.respond_to?(:[])
-        ary.reject{ |a| a[property].nil? }
+        begin
+          ary.reject { |a| a[property].nil? }
+        rescue TypeError
+          raise_property_error(property)
+        end
       end
     end
 
@@ -353,6 +403,22 @@ module Liquid
       raise Liquid::FloatDomainError, e.message
     end
 
+    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 = ''.freeze)
       if !input || input.respond_to?(:empty?) && input.empty?
         default_value
@@ -363,11 +429,31 @@ module Liquid
 
     private
 
+    def raise_property_error(property)
+      raise Liquid::ArgumentError.new("cannot select the property '#{property}'")
+    end
+
     def apply_operation(input, operand, operation)
       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
 

lib/liquid/tags/assign.rb

@@ -10,6 +10,8 @@ module Liquid
   class Assign < Tag
     Syntax = /(#{VariableSignature}+)\s*=\s*(.*)\s*/om
 
+    attr_reader :to, :from
+
     def initialize(tag_name, markup, options)
       super
       if markup =~ Syntax
@@ -45,6 +47,12 @@ module Liquid
         1
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.from]
+      end
+    end
   end
 
   Template.register_tag('assign'.freeze, Assign)

lib/liquid/tags/case.rb

@@ -3,6 +3,8 @@ module Liquid
     Syntax     = /(#{QuotedFragment})/o
     WhenSyntax = /(#{QuotedFragment})(?:(?:\s+or\s+|\s*\,\s*)(#{QuotedFragment}.*))?/om
 
+    attr_reader :blocks, :left
+
     def initialize(tag_name, markup, options)
       super
       @blocks = []
@@ -80,6 +82,12 @@ module Liquid
       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)

lib/liquid/tags/cycle.rb

@@ -15,6 +15,8 @@ module Liquid
     SimpleSyntax = /\A#{QuotedFragment}+/o
     NamedSyntax  = /\A(#{QuotedFragment})\s*\:\s*(.*)/om
 
+    attr_reader :variables
+
     def initialize(tag_name, markup, options)
       super
       case markup
@@ -30,11 +32,11 @@ module Liquid
     end
 
     def render(context)
-      context.registers[:cycle] ||= Hash.new(0)
+      context.registers[:cycle] ||= {}
 
       context.stack do
         key = context.evaluate(@name)
-        iteration = context.registers[:cycle][key]
+        iteration = context.registers[:cycle][key].to_i
         result = context.evaluate(@variables[iteration])
         iteration += 1
         iteration  = 0 if iteration >= @variables.size
@@ -51,6 +53,12 @@ module Liquid
         $1 ? Expression.parse($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/for.rb

@@ -46,8 +46,7 @@ module Liquid
   class For < Block
     Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
 
-    attr_reader :collection_name
-    attr_reader :variable_name
+    attr_reader :collection_name, :variable_name, :limit, :from
 
     def initialize(tag_name, markup, options)
       super
@@ -120,7 +119,7 @@ module Liquid
     private
 
     def collection_segment(context)
-      offsets = context.registers[:for] ||= Hash.new(0)
+      offsets = context.registers[:for] ||= {}
 
       from = if @from == :continue
         offsets[@name].to_i
@@ -156,7 +155,7 @@ module Liquid
         begin
           context['forloop'.freeze] = loop_vars
 
-          segment.each_with_index do |item, index|
+          segment.each do |item|
             context[@variable_name] = item
             result << @for_block.render(context)
             loop_vars.send(:increment!)
@@ -192,6 +191,12 @@ module Liquid
     def render_else(context)
       @else_block ? @else_block.render(context) : ''.freeze
     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)

lib/liquid/tags/if.rb

@@ -12,7 +12,9 @@ module Liquid
   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)
+    BOOLEAN_OPERATORS = %w(and or).freeze
+
+    attr_reader :blocks
 
     def initialize(tag_name, markup, options)
       super
@@ -20,15 +22,15 @@ module Liquid
       push_block('if'.freeze, markup)
     end
 
+    def nodelist
+      @blocks.map(&:attachment)
+    end
+
     def parse(tokens)
       while parse_body(@blocks.last.attachment, tokens)
       end
     end
 
-    def nodelist
-      @blocks.map(&:attachment)
-    end
-
     def unknown_tag(tag, markup, tokens)
       if ['elsif'.freeze, 'else'.freeze].include?(tag)
         push_block(tag, markup)
@@ -108,6 +110,12 @@ module Liquid
         Condition.new(a)
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        @node.blocks
+      end
+    end
   end
 
   Template.register_tag('if'.freeze, If)

lib/liquid/tags/include.rb

@@ -16,6 +16,8 @@ module Liquid
   class Include < Tag
     Syntax = /(#{QuotedFragment}+)(\s+(?:with|for)\s+(#{QuotedFragment}+))?/o
 
+    attr_reader :template_name_expr, :variable_name_expr, :attributes
+
     def initialize(tag_name, markup, options)
       super
 
@@ -107,6 +109,15 @@ module Liquid
 
       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)

lib/liquid/tags/table_row.rb

@@ -2,6 +2,8 @@ module Liquid
   class TableRow < Block
     Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)/o
 
+    attr_reader :variable_name, :collection_name, :attributes
+
     def initialize(tag_name, markup, options)
       super
       if markup =~ Syntax
@@ -33,7 +35,7 @@ module Liquid
         tablerowloop = Liquid::TablerowloopDrop.new(length, cols)
         context['tablerowloop'.freeze] = tablerowloop
 
-        collection.each_with_index do |item, index|
+        collection.each do |item|
           context[@variable_name] = item
 
           result << "<td class=\"col#{tablerowloop.col}\">" << super << '</td>'
@@ -48,6 +50,12 @@ module Liquid
       result << "</tr>\n"
       result
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        super + @node.attributes.values + [@node.collection_name]
+      end
+    end
   end
 
   Template.register_tag('tablerow'.freeze, TableRow)

lib/liquid/utils.rb

@@ -46,11 +46,11 @@ module Liquid
     def self.to_number(obj)
       case obj
       when Float
-        BigDecimal.new(obj.to_s)
+        BigDecimal(obj.to_s)
       when Numeric
         obj
       when String
-        (obj.strip =~ /\A-?\d+\.\d+\z/) ? BigDecimal.new(obj) : obj.to_i
+        (obj.strip =~ /\A-?\d+\.\d+\z/) ? BigDecimal(obj) : obj.to_i
       else
         if obj.respond_to?(:to_number)
           obj.to_number

lib/liquid/variable.rb

@@ -10,10 +10,16 @@ module Liquid
   #   {{ user | link }}
   #
   class Variable
+    FilterMarkupRegex = /#{FilterSeparator}\s*(.*)/om
     FilterParser = /(?:\s+|#{QuotedFragment}|#{ArgumentSeparator})+/o
+    FilterArgsRegex = /(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o
+    JustTagAttributes = /\A#{TagAttributes}\z/o
+    MarkupWithQuotedFragment = /(#{QuotedFragment})(.*)/om
+
     attr_accessor :filters, :name, :line_number
     attr_reader :parse_context
     alias_method :options, :parse_context
+
     include ParserSwitching
 
     def initialize(markup, parse_context)
@@ -35,17 +41,17 @@ module Liquid
 
     def lax_parse(markup)
       @filters = []
-      return unless markup =~ /(#{QuotedFragment})(.*)/om
+      return unless markup =~ MarkupWithQuotedFragment
 
       name_markup = $1
       filter_markup = $2
       @name = Expression.parse(name_markup)
-      if filter_markup =~ /#{FilterSeparator}\s*(.*)/om
+      if filter_markup =~ FilterMarkupRegex
         filters = $1.scan(FilterParser)
         filters.each do |f|
           next unless f =~ /\w+/
           filtername = Regexp.last_match(0)
-          filterargs = f.scan(/(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o).flatten
+          filterargs = f.scan(FilterArgsRegex).flatten
           @filters << parse_filter_expressions(filtername, filterargs)
         end
       end
@@ -91,7 +97,7 @@ module Liquid
       filter_args = []
       keyword_args = {}
       unparsed_args.each do |a|
-        if matches = a.match(/\A#{TagAttributes}\z/o)
+        if matches = a.match(JustTagAttributes)
           keyword_args[matches[1]] = Expression.parse(matches[2])
         else
           filter_args << Expression.parse(a)
@@ -132,5 +138,11 @@ module Liquid
         raise error
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.name] + @node.filters.flatten
+      end
+    end
   end
 end

lib/liquid/variable_lookup.rb

@@ -1,7 +1,7 @@
 module Liquid
   class VariableLookup
     SQUARE_BRACKETED = /\A\[(.*)\]\z/m
-    COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze]
+    COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze].freeze
 
     attr_reader :name, :lookups
 
@@ -78,5 +78,11 @@ module Liquid
     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
+
 module Liquid
-  VERSION = "4.0.0"
+  VERSION = "4.0.2".freeze
 end

liquid.gemspec

@@ -1,4 +1,5 @@
 # encoding: utf-8
+
 lib = File.expand_path('../lib/', __FILE__)
 $LOAD_PATH.unshift lib unless $LOAD_PATH.include?(lib)
 

test/integration/block_test.rb

@@ -0,0 +1,12 @@
+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/error_handling_test.rb

@@ -123,7 +123,7 @@ class ErrorHandlingTest < Minitest::Test
             ',
       error_mode: :warn,
       line_numbers: true
-                                     )
+    )
 
     assert_equal ['Liquid syntax error (line 4): Unexpected character = in "1 =! 2"'],
       template.warnings.map(&:message)
@@ -140,7 +140,7 @@ class ErrorHandlingTest < Minitest::Test
                 ',
         error_mode: :strict,
         line_numbers: true
-                            )
+      )
     end
 
     assert_equal 'Liquid syntax error (line 4): Unexpected character = in "1 =! 2"', err.message
@@ -158,7 +158,7 @@ class ErrorHandlingTest < Minitest::Test
           bla
                 ',
         line_numbers: true
-                            )
+      )
     end
 
     assert_equal "Liquid syntax error (line 5): Unknown tag 'foo'", err.message

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(
+      ["test", "infilter"],
+      visit(%({{ test | split: infilter }}))
+    )
+  end
+
+  def test_dynamic_variable
+    assert_equal(
+      ["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

@@ -99,7 +99,7 @@ class ParsingQuirksTest < Minitest::Test
       # 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}}")
+      assert_template_result('hi ', "{{ 'hi there' | split:\"t\"\" | remove:\"i\" | first}}")
     end
   end
 

test/integration/standard_filter_test.rb

@@ -158,6 +158,10 @@ class StandardFiltersTest < Minitest::Test
     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
@@ -177,6 +181,9 @@ class StandardFiltersTest < Minitest::Test
     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
@@ -190,6 +197,11 @@ class StandardFiltersTest < Minitest::Test
     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" },
@@ -208,14 +220,89 @@ class StandardFiltersTest < Minitest::Test
     assert_equal expectation, @filters.sort(input, "price")
   end
 
+  def test_sort_natural
+    assert_equal ["a", "B", "c", "D"], @filters.sort_natural(["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 ["a", "b", "c", "X", "Y", "Z"], @filters.sort_natural(["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 })
   end
@@ -239,10 +326,34 @@ class StandardFiltersTest < Minitest::Test
     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])
   end
@@ -308,6 +419,29 @@ class StandardFiltersTest < Minitest::Test
     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
   end
@@ -338,9 +472,9 @@ class StandardFiltersTest < Minitest::Test
     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 "#{Date.today.year}", @filters.date('Today', '%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_nil @filters.date(nil, "%B")
 
@@ -496,6 +630,28 @@ class StandardFiltersTest < Minitest::Test
     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)
@@ -536,6 +692,78 @@ class StandardFiltersTest < Minitest::Test
     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)

test/integration/tags/for_tag_test.rb

@@ -159,7 +159,7 @@ HERE
     assert_template_result(expected, markup, assigns)
   end
 
-  def test_pause_resume_BIG_limit
+  def test_pause_resume_big_limit
     assigns = { 'array' => { 'items' => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] } }
     markup = <<-MKUP
       {%for i in array.items limit:3 %}{{i}}{%endfor%}
@@ -178,7 +178,7 @@ HERE
     assert_template_result(expected, markup, assigns)
   end
 
-  def test_pause_resume_BIG_offset
+  def test_pause_resume_big_offset
     assigns = { 'array' => { 'items' => [1, 2, 3, 4, 5, 6, 7, 8, 9, 0] } }
     markup = '{%for i in array.items limit:3 %}{{i}}{%endfor%}
       next

test/integration/template_test.rb

@@ -261,6 +261,15 @@ class TemplateTest < Minitest::Test
     assert_equal 'Liquid error: undefined variable d', t.errors[2].message
   end
 
+  def test_nil_value_does_not_raise
+    Liquid::Template.error_mode = :strict
+    t = Template.parse("some{{x}}thing")
+    result = t.render!({ 'x' => nil }, strict_variables: true)
+
+    assert_equal 0, t.errors.count
+    assert_equal 'something', result
+  end
+
   def test_undefined_variables_raise
     t = Template.parse("{{x}} {{y}} {{z.a}} {{z.b}} {{z.c.d}}")
 

test/integration/trim_mode_test.rb

@@ -496,6 +496,10 @@ class TrimModeTest < Minitest::Test
     assert_template_result(expected, text)
   end
 
+  def test_right_trim_followed_by_tag
+    assert_template_result('ab c', '{{ "a" -}}{{ "b" }} c')
+  end
+
   def test_raw_output
     whitespace = '        '
     text = <<-END_TEMPLATE

test/integration/variable_test.rb

@@ -89,4 +89,8 @@ class VariableTest < Minitest::Test
   def test_multiline_variable
     assert_equal 'worked', Template.parse("{{\ntest\n}}").render!('test' => 'worked')
   end
+
+  def test_render_symbol
+    assert_template_result 'bar', '{{ foo }}', 'foo' => :bar
+  end
 end

test/unit/condition_unit_test.rb

@@ -24,9 +24,9 @@ class ConditionUnitTest < Minitest::Test
     assert_evaluates_true 1, '<=', 1
     # negative numbers
     assert_evaluates_true 1, '>', -1
-    assert_evaluates_true (-1), '<', 1
+    assert_evaluates_true -1, '<', 1
     assert_evaluates_true 1.0, '>', -1.0
-    assert_evaluates_true (-1.0), '<', 1.0
+    assert_evaluates_true -1.0, '<', 1.0
   end
 
   def test_default_operators_evalute_false