Optimize range iteration

For loops support a range syntax for iterating a fixed number of times,
which looks like this.

```liquid
{% for i in range (1..100) %}
        ...
{% endfor %}
```

Previously, we converted these ranges to arrays using `to_a`, which
initialized an array containing each number in the range. Since all we
use these ranges for is iteration, this is far less efficient than
using a range iterator.

Doing this means that iterating over ranges now takes O(1) rather than O(n)
memory. See the PR for more benchmarks.

* Remove to_a cast on ranges
* Add ReversableRange iterator
* Add custom range-specific slicing logic

.gitignore

@@ -7,4 +7,3 @@ pkg
 .ruby-version
 Gemfile.lock
 .bundle
-.byebug_history

.rubocop.yml

@@ -1,16 +1,132 @@
 inherit_from:
-  - https://shopify.github.io/ruby-style-guide/rubocop.yml
   - .rubocop_todo.yml
-
+  - ./.rubocop_todo.yml
-require: rubocop-performance
-
-Performance:
-  Enabled: true
 
 AllCops:
   Exclude:
-    - 'vendor/bundle/**/*'
+    - 'performance/shopify/*'
-      
+    - 'pkg/**'
+
+Metrics/BlockNesting:
+  Max: 3
+
+Metrics/ModuleLength:
+  Enabled: false
+
+Metrics/ClassLength:
+  Enabled: false
+
+Lint/AssignmentInCondition:
+  Enabled: false
+
+Lint/AmbiguousOperator:
+  Enabled: false
+
+Lint/AmbiguousRegexpLiteral:
+  Enabled: false
+
+Lint/ParenthesesAsGroupedExpression:
+  Enabled: false
+
+Lint/UnusedBlockArgument:
+  Enabled: false
+
+Layout/EndAlignment:
+  EnforcedStyleAlignWith: variable
+
+Lint/UnusedMethodArgument:
+  Enabled: false
+
+Style/SingleLineBlockParams:
+  Enabled: false
+
+Style/DoubleNegation:
+  Enabled: false
+
+Style/StringLiteralsInInterpolation:
+  Enabled: false
+
+Style/AndOr:
+  Enabled: false
+
+Style/SignalException:
+  Enabled: false
+
+Style/StringLiterals:
+  Enabled: false
+
+Style/BracesAroundHashParameters:
+  Enabled: false
+
+Style/NumericLiterals:
+  Enabled: false
+
+Layout/SpaceInsideArrayLiteralBrackets:
+  Enabled: false
+
+Layout/SpaceBeforeBlockBraces:
+  Enabled: false
+
+Style/Documentation:
+  Enabled: false
+
+Style/ClassAndModuleChildren:
+  Enabled: false
+
+Style/TrailingCommaInArrayLiteral:
+  Enabled: false
+
+Style/TrailingCommaInHashLiteral:
+  Enabled: false
+
+Layout/IndentHash:
+  EnforcedStyle: consistent
+
+Style/FormatString:
+  Enabled: false
+
+Layout/AlignParameters:
+  EnforcedStyle: with_fixed_indentation
+
+Layout/MultilineOperationIndentation:
+  EnforcedStyle: indented
+
+Style/IfUnlessModifier:
+  Enabled: false
+
+Style/RaiseArgs:
+  Enabled: false
+
+Style/PreferredHashMethods:
+  Enabled: false
+
+Style/RegexpLiteral:
+  Enabled: false
+
+Style/SymbolLiteral:
+  Enabled: false
+
+Performance/Count:
+  Enabled: false
+
+Naming/ConstantName:
+  Enabled: false
+
+Layout/CaseIndentation:
+  Enabled: false
+
+Style/ClassVars:
+  Enabled: false
+
+Style/PerlBackrefs:
+  Enabled: false
+
+Style/TrivialAccessors:
+  AllowPredicates: true
+
+Style/WordArray:
+  Enabled: false
+
 Naming/MethodName:
   Exclude:
-    - 'example/server/liquid_servlet.rb'
+    - 'example/server/liquid_servlet.rb'

.rubocop_todo.yml

@@ -1,37 +1,23 @@
 # This configuration was generated by
 # `rubocop --auto-gen-config`
-# on 2019-08-29 12:16:25 +1000 using RuboCop version 0.74.0.
+# on 2019-03-19 11:04:37 -0400 using RuboCop version 0.53.0.
 # 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: 13
+# Offense count: 1
 # Cop supports --auto-correct.
-# Configuration parameters: AllowMultipleStyles, EnforcedHashRocketStyle, EnforcedColonStyle, EnforcedLastArgumentHashStyle.
+# Configuration parameters: Include, TreatCommentsAsGroupSeparators.
-# SupportedHashRocketStyles: key, separator, table
+# Include: **/*.gemspec
-# SupportedColonStyles: key, separator, table
+Gemspec/OrderedDependencies:
-# SupportedLastArgumentHashStyles: always_inspect, always_ignore, ignore_implicit, ignore_explicit
-Layout/AlignHash:
   Exclude:
-    - 'lib/liquid/condition.rb'
+    - 'liquid.gemspec'
-    - 'lib/liquid/expression.rb'
-    - 'performance/shopify/comment_form.rb'
-    - 'performance/shopify/database.rb'
-    - 'performance/shopify/paginate.rb'
-    - 'test/unit/context_unit_test.rb'
-
-# Offense count: 3
-# Cop supports --auto-correct.
-# Configuration parameters: AllowForAlignment, AllowBeforeTrailingComments, ForceEqualSignAlignment.
-Layout/ExtraSpacing:
-  Exclude:
-    - 'performance/shopify/paginate.rb'
 
 # Offense count: 5
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.
-# SupportedStyles: squiggly, active_support, powerpack, unindent
+# SupportedStyles: auto_detection, squiggly, active_support, powerpack, unindent
 Layout/IndentHeredoc:
   Exclude:
     - 'test/integration/tags/for_tag_test.rb'
@@ -46,62 +32,6 @@ Layout/MultilineMethodCallBraceLayout:
     - 'test/integration/error_handling_test.rb'
     - 'test/unit/strainer_unit_test.rb'
 
-# Offense count: 4
-# Cop supports --auto-correct.
-# Configuration parameters: AllowForAlignment.
-Layout/SpaceAroundOperators:
-  Exclude:
-    - 'lib/liquid/condition.rb'
-    - 'performance/shopify/paginate.rb'
-
-# Offense count: 9
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle, EnforcedStyleForEmptyBraces.
-# SupportedStyles: space, no_space
-# SupportedStylesForEmptyBraces: space, no_space
-Layout/SpaceBeforeBlockBraces:
-  Exclude:
-    - 'example/server/server.rb'
-    - 'lib/liquid/variable.rb'
-    - 'test/integration/drop_test.rb'
-    - 'test/integration/standard_filter_test.rb'
-    - 'test/integration/tags/if_else_tag_test.rb'
-
-# Offense count: 19
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle, EnforcedStyleForEmptyBrackets.
-# SupportedStyles: space, no_space, compact
-# SupportedStylesForEmptyBrackets: space, no_space
-Layout/SpaceInsideArrayLiteralBrackets:
-  Exclude:
-    - 'test/integration/drop_test.rb'
-    - 'test/integration/standard_filter_test.rb'
-    - 'test/integration/tags/for_tag_test.rb'
-    - 'test/integration/tags/include_tag_test.rb'
-    - 'test/integration/tags/standard_tag_test.rb'
-    - 'test/unit/context_unit_test.rb'
-
-# Offense count: 2
-Lint/AmbiguousOperator:
-  Exclude:
-    - 'test/unit/condition_unit_test.rb'
-
-# Offense count: 16
-# Configuration parameters: AllowSafeAssignment.
-Lint/AssignmentInCondition:
-  Exclude:
-    - 'lib/liquid/block_body.rb'
-    - 'lib/liquid/lexer.rb'
-    - 'lib/liquid/standardfilters.rb'
-    - 'lib/liquid/tags/for.rb'
-    - 'lib/liquid/tags/if.rb'
-    - 'lib/liquid/tags/include.rb'
-    - 'lib/liquid/tags/raw.rb'
-    - 'lib/liquid/variable.rb'
-    - 'performance/profile.rb'
-    - 'test/test_helper.rb'
-    - 'test/unit/tokenizer_unit_test.rb'
-
 # Offense count: 2
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.
@@ -110,184 +40,145 @@ Lint/InheritException:
   Exclude:
     - 'lib/liquid/interrupts.rb'
 
-# Offense count: 10
-# Cop supports --auto-correct.
-# Configuration parameters: IgnoreEmptyBlocks, AllowUnusedKeywordArguments.
-Lint/UnusedBlockArgument:
-  Exclude:
-    - 'lib/liquid/condition.rb'
-    - 'lib/liquid/context.rb'
-    - 'lib/liquid/document.rb'
-    - 'lib/liquid/parse_context.rb'
-    - 'lib/liquid/template.rb'
-    - 'performance/shopify/json_filter.rb'
-    - 'test/integration/filter_test.rb'
-    - 'test/integration/render_profiling_test.rb'
-    - 'test/integration/variable_test.rb'
-    - 'test/unit/condition_unit_test.rb'
-
-# Offense count: 12
-# Cop supports --auto-correct.
-# Configuration parameters: AllowUnusedKeywordArguments, IgnoreEmptyMethods.
-Lint/UnusedMethodArgument:
-  Exclude:
-    - 'example/server/liquid_servlet.rb'
-    - 'test/integration/blank_test.rb'
-    - 'test/integration/error_handling_test.rb'
-    - 'test/integration/filter_test.rb'
-    - 'test/integration/output_test.rb'
-    - 'test/integration/standard_filter_test.rb'
-    - 'test/integration/tags/include_tag_test.rb'
-    - 'test/unit/strainer_unit_test.rb'
-
-# Offense count: 2
-Lint/UselessAssignment:
-  Exclude:
-    - 'performance/shopify/database.rb'
-
 # Offense count: 1
 # Configuration parameters: CheckForMethodsWithNoSideEffects.
 Lint/Void:
   Exclude:
     - 'lib/liquid/parse_context.rb'
 
-# Offense count: 95
+# Offense count: 54
-# Cop supports --auto-correct.
+Metrics/AbcSize:
-# Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
+  Max: 56
-# URISchemes: http, https
-Metrics/LineLength:
-  Max: 294
 
-# Offense count: 44
+# Offense count: 12
-Naming/ConstantName:
+Metrics/CyclomaticComplexity:
+  Max: 12
+
+# Offense count: 112
+# Configuration parameters: CountComments.
+Metrics/MethodLength:
+  Max: 37
+
+# Offense count: 8
+Metrics/PerceivedComplexity:
+  Max: 11
+
+# Offense count: 52
+# Configuration parameters: Blacklist.
+# Blacklist: END, (?-mix:EO[A-Z]{1})
+Naming/HeredocDelimiterNaming:
   Exclude:
-    - 'lib/liquid.rb'
+    - 'test/integration/assign_test.rb'
-    - 'lib/liquid/block_body.rb'
+    - 'test/integration/capture_test.rb'
-    - 'lib/liquid/tags/assign.rb'
+    - 'test/integration/trim_mode_test.rb'
-    - 'lib/liquid/tags/capture.rb'
+
-    - 'lib/liquid/tags/case.rb'
+# Offense count: 23
-    - 'lib/liquid/tags/cycle.rb'
+# Configuration parameters: MinNameLength, AllowNamesEndingInNumbers, AllowedNames, ForbiddenNames.
-    - 'lib/liquid/tags/for.rb'
+# AllowedNames: io, id
+Naming/UncommunicativeMethodParamName:
+  Exclude:
+    - 'example/server/example_servlet.rb'
+    - 'lib/liquid/condition.rb'
+    - 'lib/liquid/context.rb'
+    - 'lib/liquid/standardfilters.rb'
     - 'lib/liquid/tags/if.rb'
-    - 'lib/liquid/tags/include.rb'
+    - 'lib/liquid/utils.rb'
-    - 'lib/liquid/tags/raw.rb'
-    - 'lib/liquid/tags/table_row.rb'
     - 'lib/liquid/variable.rb'
-    - 'performance/shopify/comment_form.rb'
-    - 'performance/shopify/paginate.rb'
-    - 'test/integration/tags/include_tag_test.rb'
-
-# Offense count: 2
-# Configuration parameters: .
-# SupportedStyles: snake_case, camelCase
-Naming/MethodName:
-  EnforcedStyle: snake_case
-
-# Offense count: 3
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: always, conditionals
-Style/AndOr:
-  Exclude:
-    - 'lib/liquid/i18n.rb'
-    - 'lib/liquid/tags/table_row.rb'
-    - 'lib/liquid/tokenizer.rb'
-
-# Offense count: 40
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: braces, no_braces, context_dependent
-Style/BracesAroundHashParameters:
-  Exclude:
-    - 'test/integration/error_handling_test.rb'
     - 'test/integration/filter_test.rb'
-    - 'test/integration/render_profiling_test.rb'
     - 'test/integration/standard_filter_test.rb'
-    - 'test/integration/tags/echo_test.rb'
+    - 'test/integration/tags/for_tag_test.rb'
-    - 'test/integration/tags/increment_tag_test.rb'
-    - 'test/integration/tags/standard_tag_test.rb'
     - 'test/integration/template_test.rb'
     - 'test/unit/condition_unit_test.rb'
-    - 'test/unit/context_unit_test.rb'
 
-# Offense count: 5
+# Offense count: 10
-Style/ClassVars:
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: prefer_alias, prefer_alias_method
+Style/Alias:
   Exclude:
-    - 'lib/liquid/condition.rb'
+    - 'lib/liquid/drop.rb'
-    - 'lib/liquid/strainer.rb'
+    - 'lib/liquid/i18n.rb'
-    - 'lib/liquid/template.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: 2
+# Offense count: 22
+Style/CommentedKeyword:
+  Enabled: false
+
+# Offense count: 1
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle, SingleLineConditionsOnly, IncludeTernaryExpressions.
 # SupportedStyles: assign_to_condition, assign_inside_condition
 Style/ConditionalAssignment:
   Exclude:
     - 'lib/liquid/errors.rb'
-    - 'performance/shopify/shop_filter.rb'
 
 # Offense count: 1
-# Configuration parameters: AllowCoercion.
 Style/DateTime:
   Exclude:
     - 'test/unit/context_unit_test.rb'
 
 # Offense count: 2
 # Cop supports --auto-correct.
-Style/EachWithObject:
-  Exclude:
-    - 'performance/shopify/database.rb'
-
-# Offense count: 1
-# Cop supports --auto-correct.
 Style/EmptyCaseCondition:
   Exclude:
+    - 'lib/liquid/block_body.rb'
     - 'lib/liquid/lexer.rb'
 
-# Offense count: 1
+# Offense count: 5
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.
-# SupportedStyles: each, for
+# SupportedStyles: compact, expanded
-Style/For:
+Style/EmptyMethod:
   Exclude:
-    - 'performance/shopify/shop_filter.rb'
+    - '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: 9
+# Offense count: 3
 # Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
+Style/Encoding:
-# SupportedStyles: format, sprintf, percent
+  Exclude:
-Style/FormatString:
+    - 'lib/liquid/version.rb'
+    - 'liquid.gemspec'
+    - 'test/integration/standard_filter_test.rb'
+
+# Offense count: 2
+# Cop supports --auto-correct.
+Style/ExpandPathArguments:
+  Exclude:
+    - 'Rakefile'
+    - 'liquid.gemspec'
+
+# Offense count: 7
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: annotated, template, unannotated
+Style/FormatStringToken:
   Exclude:
-    - 'example/server/example_servlet.rb'
-    - 'performance/shopify/money_filter.rb'
-    - 'performance/shopify/weight_filter.rb'
     - 'test/integration/filter_test.rb'
     - 'test/integration/hash_ordering_test.rb'
 
-# Offense count: 115
+# Offense count: 14
-# Cop supports --auto-correct.
+# Configuration parameters: MinBodyLength.
-# Configuration parameters: EnforcedStyle.
+Style/GuardClause:
-# SupportedStyles: always, never
-Style/FrozenStringLiteralComment:
-  Enabled: false
-
-# Offense count: 30
-# Cop supports --auto-correct.
-# Configuration parameters: IgnoreMacros, IgnoredMethods, IncludedMacros, AllowParenthesesInMultilineCall, AllowParenthesesInChaining, AllowParenthesesInCamelCaseMethod, EnforcedStyle.
-# SupportedStyles: require_parentheses, omit_parentheses
-Style/MethodCallWithArgsParentheses:
   Exclude:
-    - 'Gemfile'
+    - 'lib/liquid/condition.rb'
-    - 'Rakefile'
+    - 'lib/liquid/lexer.rb'
-    - 'lib/liquid/block_body.rb'
+    - 'lib/liquid/strainer.rb'
-    - 'lib/liquid/parser.rb'
+    - 'lib/liquid/tags/assign.rb'
+    - 'lib/liquid/tags/capture.rb'
+    - 'lib/liquid/tags/case.rb'
     - 'lib/liquid/tags/for.rb'
-    - 'liquid.gemspec'
+    - 'lib/liquid/tags/include.rb'
-    - 'performance/shopify/database.rb'
+    - 'lib/liquid/tags/raw.rb'
-    - 'performance/shopify/liquid.rb'
+    - 'lib/liquid/tags/table_row.rb'
-    - 'test/test_helper.rb'
+    - 'lib/liquid/variable.rb'
-    - 'test/unit/condition_unit_test.rb'
+    - 'test/unit/tokenizer_unit_test.rb'
-    - 'test/unit/tags/if_tag_unit_test.rb'
 
 # Offense count: 1
 # Cop supports --auto-correct.
@@ -297,17 +188,27 @@ Style/Next:
   Exclude:
     - 'lib/liquid/tags/for.rb'
 
-# Offense count: 52
+# Offense count: 4
 # Cop supports --auto-correct.
-Style/PerlBackrefs:
+# Configuration parameters: AutoCorrect, EnforcedStyle.
-  Enabled: false
+# 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: 33
+# Offense count: 14
 # Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
+# Configuration parameters: PreferredDelimiters.
-# SupportedStyles: compact, exploded
+Style/PercentLiteralDelimiters:
-Style/RaiseArgs:
+  Exclude:
-  Enabled: false
+    - '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.
@@ -315,52 +216,21 @@ Style/RedundantSelf:
   Exclude:
     - 'lib/liquid/strainer.rb'
 
-# Offense count: 5
+# Offense count: 9
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle, AllowInnerSlashes.
-# SupportedStyles: slashes, percent_r, mixed
-Style/RegexpLiteral:
-  Exclude:
-    - 'lib/liquid/file_system.rb'
-    - 'lib/liquid/standardfilters.rb'
-    - 'performance/shopify/shop_filter.rb'
-    - 'test/unit/condition_unit_test.rb'
-
-# Offense count: 3
-# Cop supports --auto-correct.
-# Configuration parameters: ConvertCodeThatCanStartToReturnNil, Whitelist.
-# Whitelist: present?, blank?, presence, try, try!
-Style/SafeNavigation:
-  Exclude:
-    - 'lib/liquid/drop.rb'
-    - 'lib/liquid/strainer.rb'
-    - 'lib/liquid/tokenizer.rb'
-
-# Offense count: 10
 # Cop supports --auto-correct.
 # Configuration parameters: AllowAsExpressionSeparator.
 Style/Semicolon:
   Exclude:
-    - 'performance/shopify/database.rb'
     - 'test/integration/error_handling_test.rb'
     - 'test/integration/template_test.rb'
     - 'test/unit/context_unit_test.rb'
 
-# Offense count: 1
+# Offense count: 7
 # Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
+# Configuration parameters: MinSize.
-# SupportedStyles: use_perl_names, use_english_names
+# SupportedStyles: percent, brackets
-Style/SpecialGlobalVars:
+Style/SymbolArray:
-  Exclude:
+  EnforcedStyle: brackets
-    - 'performance/shopify/liquid.rb'
-
-# Offense count: 2
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: single_quotes, double_quotes
-Style/StringLiteralsInInterpolation:
-  Exclude:
-    - 'performance/shopify/tag_filter.rb'
 
 # Offense count: 2
 # Cop supports --auto-correct.
@@ -371,33 +241,6 @@ Style/TernaryParentheses:
     - 'lib/liquid/context.rb'
     - 'lib/liquid/utils.rb'
 
-# Offense count: 21
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyleForMultiline.
-# SupportedStylesForMultiline: comma, consistent_comma, no_comma
-Style/TrailingCommaInArrayLiteral:
-  Exclude:
-    - 'lib/liquid/parse_tree_visitor.rb'
-    - 'lib/liquid/tags/include.rb'
-    - 'test/integration/parse_tree_visitor_test.rb'
-    - 'test/integration/standard_filter_test.rb'
-
-# Offense count: 9
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyleForMultiline.
-# SupportedStylesForMultiline: comma, consistent_comma, no_comma
-Style/TrailingCommaInHashLiteral:
-  Exclude:
-    - 'lib/liquid/condition.rb'
-    - 'lib/liquid/lexer.rb'
-    - 'lib/liquid/standardfilters.rb'
-    - 'performance/shopify/comment_form.rb'
-    - 'performance/shopify/database.rb'
-    - 'performance/shopify/paginate.rb'
-    - 'performance/theme_runner.rb'
-    - 'test/integration/output_test.rb'
-    - 'test/unit/context_unit_test.rb'
-
 # Offense count: 2
 # Cop supports --auto-correct.
 Style/UnneededPercentQ:
@@ -409,3 +252,9 @@ Style/UnneededPercentQ:
 Style/WhileUntilModifier:
   Exclude:
     - 'lib/liquid/tags/case.rb'
+
+# Offense count: 640
+# Configuration parameters: AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
+# URISchemes: http, https
+Metrics/LineLength:
+  Max: 294

.travis.yml

@@ -1,30 +1,31 @@
 language: ruby
-cache: bundler
 
 rvm:
+  - 2.1
+  - 2.2
+  - 2.3
   - 2.4
   - 2.5
-  - &latest_ruby 2.6
-  - 2.7
   - ruby-head
   - jruby-head
-  - truffleruby
+#  - rbx-2
+
+sudo: false
+
+addons:
+  apt:
+    packages:
+    - libgmp3-dev
 
 matrix:
-  include:
-    - rvm: *latest_ruby
-      script: bundle exec rake memory_profile:run
-      name: Profiling Memory Usage
   allow_failures:
     - rvm: ruby-head
     - rvm: jruby-head
-    - rvm: truffleruby
 
-branches:
+install:
-  only:
+  - bundle install
-    - master
+
-    - gh-pages
+script: bundle exec rake
-    - /.*-stable/
 
 notifications:
   disable: true

Gemfile

@@ -8,18 +8,16 @@ gemspec
 group :benchmark, :test do
   gem 'benchmark-ips'
   gem 'memory_profiler'
-  gem 'terminal-table'
 
-  install_if -> { RUBY_PLATFORM !~ /mingw|mswin|java/ && RUBY_ENGINE != 'truffleruby' } do
+  install_if -> { RUBY_PLATFORM !~ /mingw|mswin|java/ } do
     gem 'stackprof'
   end
 end
 
 group :test do
-  gem 'rubocop', '~> 0.74.0', require: false
+  gem 'rubocop', '~> 0.53.0'
-  gem 'rubocop-performance', require: false
 
-  platform :mri, :truffleruby do
+  platform :mri do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'master'
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'reversable-range'
   end
 end

README.md

@@ -106,9 +106,3 @@ template = Liquid::Template.parse("{{x}} {{y}}")
 template.render!({ 'x' => 1}, { strict_variables: true })
 #=> Liquid::UndefinedVariable: Liquid error: undefined variable y
 ```
-
-### Usage tracking
-
-To help track usages of a feature or code path in production, we have released opt-in usage tracking. To enable this, we provide an empty `Liquid:: Usage.increment` method which you can customize to your needs. The feature is well suited to https://github.com/Shopify/statsd-instrument. However, the choice of implementation is up to you.
-
-Once you have enabled usage tracking, we recommend reporting any events through Github Issues that your system may be logging. It is highly likely this event has been added to consider deprecating or improving code specific to this event, so please raise any concerns.

Rakefile

@@ -19,10 +19,8 @@ task :warn_test do
 end
 
 task :rubocop do
-  if RUBY_ENGINE == 'ruby'
+  require 'rubocop/rake_task'
-    require 'rubocop/rake_task'
+  RuboCop::RakeTask.new
-    RuboCop::RakeTask.new
-  end
 end
 
 desc 'runs test suite with both strict and lax parsers'
@@ -34,8 +32,8 @@ task :test do
   Rake::Task['base_test'].reenable
   Rake::Task['base_test'].invoke
 
-  if RUBY_ENGINE == 'ruby' || RUBY_ENGINE == 'truffleruby'
+  if RUBY_ENGINE == 'ruby'
-    ENV['LIQUID_C'] = '1'
+    ENV['LIQUID-C'] = '1'
 
     ENV['LIQUID_PARSER_MODE'] = 'lax'
     Rake::Task['base_test'].reenable

lib/liquid.rb

@@ -74,8 +74,7 @@ require 'liquid/condition'
 require 'liquid/utils'
 require 'liquid/tokenizer'
 require 'liquid/parse_context'
-require 'liquid/partial_cache'
+require 'liquid/reversable_range'
-require 'liquid/usage'
 
 # Load all the tags of the standard library
 #

lib/liquid/block.rb

@@ -13,7 +13,6 @@ module Liquid
       end
     end
 
-    # For backwards compatibility
     def render(context)
       @body.render(context)
     end

lib/liquid/block_body.rb

@@ -1,7 +1,6 @@
 module Liquid
   class BlockBody
-    LiquidTagToken = /\A\s*(\w+)\s*(.*?)\z/o
+    FullToken = /\A#{TagStart}#{WhitespaceControl}?\s*(\w+)\s*(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
-    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
@@ -14,42 +13,8 @@ module Liquid
       @blank = true
     end
 
-    def parse(tokenizer, parse_context, &block)
+    def parse(tokenizer, parse_context)
       parse_context.line_number = tokenizer.line_number
-
-      if tokenizer.for_liquid_tag
-        parse_for_liquid_tag(tokenizer, parse_context, &block)
-      else
-        parse_for_document(tokenizer, parse_context, &block)
-      end
-    end
-
-    private def parse_for_liquid_tag(tokenizer, parse_context)
-      while token = tokenizer.shift
-        unless token.empty? || token =~ WhitespaceOrNothing
-          unless token =~ LiquidTagToken
-            # line isn't empty but didn't match tag syntax, yield and let the
-            # caller raise a syntax error
-            return yield token, token
-          end
-          tag_name = $1
-          markup = $2
-          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
-        end
-        parse_context.line_number = tokenizer.line_number
-      end
-
-      yield nil, nil
-    end
-
-    private def parse_for_document(tokenizer, parse_context, &block)
       while token = tokenizer.shift
         next if token.empty?
         case
@@ -58,20 +23,9 @@ module Liquid
           unless token =~ FullToken
             raise_missing_tag_terminator(token, parse_context)
           end
-          tag_name = $2
+          tag_name = $1
-          markup = $4
+          markup = $2
-
+          # fetch the tag from registered blocks
-          if parse_context.line_number
-            # newlines inside the tag should increase the line number,
-            # particularly important for multiline {% liquid %} tags
-            parse_context.line_number += $1.count("\n".freeze) + $3.count("\n".freeze)
-          end
-
-          if tag_name == 'liquid'.freeze
-            liquid_tag_tokenizer = Tokenizer.new(markup, line_number: parse_context.line_number, for_liquid_tag: true)
-            next parse_for_liquid_tag(liquid_tag_tokenizer, parse_context, &block)
-          end
-
           unless tag = registered_tags[tag_name]
             # end parsing if we reach an unknown tag and let the caller decide
             # determine how to proceed
@@ -113,23 +67,19 @@ module Liquid
     end
 
     def render(context)
-      render_to_output_buffer(context, '')
+      output = []
-    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
+          check_resources(context, node)
           output << node
         when Variable
-          render_node(context, output, node)
+          render_node_to_output(node, output, context)
         when Block
-          render_node(context, node.blank? ? '' : output, node)
+          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
@@ -138,30 +88,34 @@ module Liquid
           context.push_interrupt(node.interrupt)
           break
         else # Other non-Block tags
-          render_node(context, output, node)
+          render_node_to_output(node, output, context)
           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
+      output.join
     end
 
     private
 
-    def render_node(context, output, node)
+    def render_node_to_output(node, output, context, skip_output = false)
-      node.render_to_output_buffer(context, output)
+      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 raise_if_resource_limits_reached(context, length)
+    def check_resources(context, node_output)
-      context.resource_limits.render_length += length
+      context.resource_limits.render_length += node_output.bytesize
       return unless context.resource_limits.reached?
       raise MemoryError.new("Memory limits exceeded".freeze)
     end

lib/liquid/context.rb

@@ -12,27 +12,17 @@ module Liquid
   #
   #   context['bob']  #=> nil  class Context
   class Context
-    attr_reader :scopes, :errors, :registers, :environments, :resource_limits, :static_registers, :static_environments
+    attr_reader :scopes, :errors, :registers, :environments, :resource_limits
     attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
-    # rubocop:disable Metrics/ParameterLists
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil)
-    def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_registers: {}, static_environments: {})
+      @environments     = [environments].flatten
-      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_registers, static_environments)
+      @scopes           = [(outer_scope || {})]
-    end
+      @registers        = registers
-
+      @errors           = []
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_registers = {}, static_environments = {})
+      @partial          = false
-      @environments = [environments]
+      @strict_variables = false
-      @environments.flatten!
+      @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
-
-      @static_environments = [static_environments].flat_map(&:freeze).freeze
-      @scopes              = [(outer_scope || {})]
-      @registers           = registers
-      @static_registers    = static_registers.freeze
-      @errors              = []
-      @partial             = false
-      @strict_variables    = false
-      @resource_limits     = resource_limits || ResourceLimits.new(Template.default_resource_limits)
-      @base_scope_depth    = 0
       squash_instance_assigns_with_environments
 
       @this_stack_used = false
@@ -46,7 +36,6 @@ module Liquid
       @filters = []
       @global_filter = nil
     end
-    # rubocop:enable Metrics/ParameterLists
 
     def warnings
       @warnings ||= []
@@ -100,7 +89,7 @@ module Liquid
     # Push new local scope on the stack. use <tt>Context#stack</tt> instead
     def push(new_scope = {})
       @scopes.unshift(new_scope)
-      check_overflow
+      raise StackLevelError, "Nesting too deep".freeze if @scopes.length > Block::MAX_DEPTH
     end
 
     # Merge a hash of variables in the current local scope
@@ -137,25 +126,6 @@ module Liquid
       @this_stack_used = old_stack_used
     end
 
-    # Creates a new context inheriting resource limits, filters, environment etc.,
-    # but with an isolated scope.
-    def new_isolated_subcontext
-      check_overflow
-
-      Context.build(
-        resource_limits: resource_limits,
-        static_environments: static_environments,
-        static_registers: static_registers
-      ).tap do |subcontext|
-        subcontext.base_scope_depth = base_scope_depth + 1
-        subcontext.exception_renderer = exception_renderer
-        subcontext.filters = @filters
-        subcontext.strainer = nil
-        subcontext.errors = errors
-        subcontext.warnings = warnings
-      end
-    end
-
     def clear_instance_assigns
       @scopes[0] = {}
     end
@@ -194,13 +164,25 @@ module Liquid
       # 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 = if index
+      variable = nil
-        lookup_and_evaluate(@scopes[index], key, raise_on_not_found: raise_on_not_found)
+
-      else
+      if scope.nil?
-        try_variable_find_in_environments(key, raise_on_not_found: raise_on_not_found)
+        @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=)
 
@@ -221,38 +203,8 @@ module Liquid
       end
     end
 
-    protected
-
-    attr_writer :base_scope_depth, :warnings, :errors, :strainer, :filters
-
     private
 
-    attr_reader :base_scope_depth
-
-    def try_variable_find_in_environments(key, raise_on_not_found:)
-      @environments.each do |environment|
-        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
-        if !found_variable.nil? || @strict_variables && raise_on_not_found
-          return found_variable
-        end
-      end
-      @static_environments.each do |environment|
-        found_variable = lookup_and_evaluate(environment, key, raise_on_not_found: raise_on_not_found)
-        if !found_variable.nil? || @strict_variables && raise_on_not_found
-          return found_variable
-        end
-      end
-      nil
-    end
-
-    def check_overflow
-      raise StackLevelError, "Nesting too deep".freeze if overflow?
-    end
-
-    def overflow?
-      base_scope_depth + @scopes.length > Block::MAX_DEPTH
-    end
-
     def internal_error
       # raise and catch to set backtrace and cause on exception
       raise Liquid::InternalError, 'internal'

lib/liquid/locales/en.yml

@@ -22,6 +22,5 @@
       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"
-      render: "Syntax error in tag 'render' - Template name must be a quoted string"
     argument:
       include: "Argument error in tag 'include' - Illegal template name"

lib/liquid/parser.rb

@@ -44,14 +44,11 @@ module Liquid
       tok[0] == type
     end
 
-    SINGLE_TOKEN_EXPRESSION_TYPES = [:string, :number].freeze
-    private_constant :SINGLE_TOKEN_EXPRESSION_TYPES
-
     def expression
       token = @tokens[@p]
       if token[0] == :id
         variable_signature
-      elsif SINGLE_TOKEN_EXPRESSION_TYPES.include? token[0]
+      elsif [:string, :number].include? token[0]
         consume
       elsif token.first == :open_round
         consume

lib/liquid/partial_cache.rb

@@ -1,18 +0,0 @@
-module Liquid
-  class PartialCache
-    def self.load(template_name, context:, parse_context:)
-      cached_partials = (context.registers[:cached_partials] ||= {})
-      cached = cached_partials[template_name]
-      return cached if cached
-
-      file_system = (context.registers[:file_system] ||= Liquid::Template.file_system)
-      source = file_system.read_template_file(template_name)
-      parse_context.partial = true
-
-      partial = Liquid::Template.parse(source, parse_context)
-      cached_partials[template_name] = partial
-    ensure
-      parse_context.partial = false
-    end
-  end
-end

lib/liquid/profiler/hooks.rb

@@ -1,23 +1,23 @@
 module Liquid
   class BlockBody
-    def render_node_with_profiling(context, output, node)
+    def render_node_with_profiling(node, output, context, skip_output = false)
       Profiler.profile_node_render(node) do
-        render_node_without_profiling(context, output, node)
+        render_node_without_profiling(node, output, context, skip_output)
       end
     end
 
-    alias_method :render_node_without_profiling, :render_node
+    alias_method :render_node_without_profiling, :render_node_to_output
-    alias_method :render_node, :render_node_with_profiling
+    alias_method :render_node_to_output, :render_node_with_profiling
   end
 
   class Include < Tag
-    def render_to_output_buffer_with_profiling(context, output)
+    def render_with_profiling(context)
       Profiler.profile_children(context.evaluate(@template_name_expr).to_s) do
-        render_to_output_buffer_without_profiling(context, output)
+        render_without_profiling(context)
       end
     end
 
-    alias_method :render_to_output_buffer_without_profiling, :render_to_output_buffer
+    alias_method :render_without_profiling, :render
-    alias_method :render_to_output_buffer, :render_to_output_buffer_with_profiling
+    alias_method :render, :render_with_profiling
   end
 end

lib/liquid/range_lookup.rb

@@ -6,7 +6,7 @@ module Liquid
       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
+        ReversableRange.new(start_obj.to_i, end_obj.to_i)
       end
     end
 
@@ -18,7 +18,7 @@ module Liquid
     def evaluate(context)
       start_int = to_integer(context.evaluate(@start_obj))
       end_int = to_integer(context.evaluate(@end_obj))
-      start_int..end_int
+      ReversableRange.new(start_int, end_int)
     end
 
     private

lib/liquid/reversable_range.rb

@@ -0,0 +1,77 @@
+module Liquid
+  class ReversableRange
+    include Enumerable
+
+    def initialize(min, max)
+      @min = min
+      @max = max
+      @reversed = false
+    end
+
+    def each
+      if reversed
+        index = max
+        while index >= min
+          yield index
+          index -= 1
+        end
+      else
+        index = min
+        while index <= max
+          yield index
+          index += 1
+        end
+      end
+    end
+
+    def reverse!
+      @reversed = !reversed
+      self
+    end
+
+    def empty?
+      max < min
+    end
+
+    def size
+      difference = max - min
+      if difference > 0
+        difference + 1
+      else
+        0
+      end
+    end
+
+    def load_slice(from, to = nil)
+      to ||= max
+      slice_max = [max, to].min
+      slice_min = [min, from].max
+      range = ReversableRange.new(slice_min, slice_max)
+      range.reverse! if reversed
+      range
+    end
+
+    def ==(other)
+      other.is_a?(self.class) &&
+        other.min == min &&
+        other.max == max &&
+        other.reversed == reversed
+    end
+
+    def to_s
+      if reversed
+        "#{max}..#{min}"
+      else
+        "#{min}..#{max}"
+      end
+    end
+
+    def to_liquid
+      self
+    end
+
+    protected
+
+    attr_reader :min, :max, :reversed
+  end
+end

lib/liquid/standardfilters.rb

@@ -79,7 +79,7 @@ module Liquid
       truncate_string_str = truncate_string.to_s
       l = length - truncate_string_str.length
       l = 0 if l < 0
-      input_str.length > length ? input_str[0...l].concat(truncate_string_str) : input_str
+      input_str.length > length ? input_str[0...l] + truncate_string_str : input_str
     end
 
     def truncatewords(input, words = 15, truncate_string = "...".freeze)
@@ -88,7 +88,7 @@ module Liquid
       words = Utils.to_integer(words)
       l = words - 1
       l = 0 if l < 0
-      wordlist.length > l ? wordlist[0..l].join(" ".freeze).concat(truncate_string.to_s) : input
+      wordlist.length > l ? wordlist[0..l].join(" ".freeze) + truncate_string.to_s : input
     end
 
     # Split input string into an array of substrings separated by given pattern.
@@ -421,7 +421,6 @@ module Liquid
 
     def default(input, default_value = ''.freeze)
       if !input || input.respond_to?(:empty?) && input.empty?
-        Usage.increment("default_filter_received_false_value") if input == false # See https://github.com/Shopify/liquid/issues/1127
         default_value
       else
         input

lib/liquid/tag.rb

@@ -5,8 +5,8 @@ module Liquid
     include ParserSwitching
 
     class << self
-      def parse(tag_name, markup, tokenizer, parse_context)
+      def parse(tag_name, markup, tokenizer, options)
-        tag = new(tag_name, markup, parse_context)
+        tag = new(tag_name, markup, options)
         tag.parse(tokenizer)
         tag
       end
@@ -36,14 +36,6 @@ module Liquid
       ''.freeze
     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

lib/liquid/tags/assign.rb

@@ -10,10 +10,6 @@ module Liquid
   class Assign < Tag
     Syntax = /(#{VariableSignature}+)\s*=\s*(.*)\s*/om
 
-    def self.syntax_error_translation_key
-      "errors.syntax.assign".freeze
-    end
-
     attr_reader :to, :from
 
     def initialize(tag_name, markup, options)
@@ -22,15 +18,15 @@ module Liquid
         @to = $1
         @from = Variable.new($2, options)
       else
-        raise SyntaxError.new(options[:locale].t(self.class.syntax_error_translation_key))
+        raise SyntaxError.new options[:locale].t("errors.syntax.assign".freeze)
       end
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       val = @from.render(context)
       context.scopes.last[@to] = val
       context.resource_limits.assign_score += assign_score_of(val)
-      output
+      ''.freeze
     end
 
     def blank?

lib/liquid/tags/capture.rb

@@ -22,12 +22,11 @@ module Liquid
       end
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
-      previous_output_size = output.bytesize
+      output = super
-      super
       context.scopes.last[@to] = output
-      context.resource_limits.assign_score += (output.bytesize - previous_output_size)
+      context.resource_limits.assign_score += output.bytesize
-      output
+      ''.freeze
     end
 
     def blank?

lib/liquid/tags/case.rb

@@ -38,21 +38,21 @@ module Liquid
       end
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       context.stack do
         execute_else_block = true
 
+        output = ''
         @blocks.each do |block|
           if block.else?
-            block.attachment.render_to_output_buffer(context, output) if execute_else_block
+            return block.attachment.render(context) if execute_else_block
           elsif block.evaluate(context)
             execute_else_block = false
-            block.attachment.render_to_output_buffer(context, output)
+            output << block.attachment.render(context)
           end
         end
+        output
       end
-
-      output
     end
 
     private

lib/liquid/tags/comment.rb

@@ -1,7 +1,7 @@
 module Liquid
   class Comment < Block
-    def render_to_output_buffer(_context, output)
+    def render(_context)
-      output
+      ''.freeze
     end
 
     def unknown_tag(_tag, _markup, _tokens)

lib/liquid/tags/cycle.rb

@@ -31,29 +31,18 @@ module Liquid
       end
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       context.registers[:cycle] ||= {}
 
       context.stack do
         key = context.evaluate(@name)
         iteration = context.registers[:cycle][key].to_i
-
+        result = context.evaluate(@variables[iteration])
-        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
         context.registers[:cycle][key] = iteration
+        result
       end
-
-      output
     end
 
     private

lib/liquid/tags/decrement.rb

@@ -23,12 +23,11 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       value = context.environments.first[@variable] ||= 0
       value -= 1
       context.environments.first[@variable] = value
-      output << value.to_s
+      value.to_s
-      output
     end
   end
 

lib/liquid/tags/echo.rb

@@ -1,24 +0,0 @@
-module Liquid
-  # Echo outputs an expression
-  #
-  #   {% echo monkey %}
-  #   {% echo user.name %}
-  #
-  # This is identical to variable output syntax, like {{ foo }}, but works
-  # inside {% liquid %} tags. The full syntax is supported, including filters:
-  #
-  #   {% echo user | link %}
-  #
-  class Echo < Tag
-    def initialize(tag_name, markup, parse_context)
-      super
-      @variable = Variable.new(markup, parse_context)
-    end
-
-    def render(context)
-      @variable.render_to_output_buffer(context, '')
-    end
-  end
-
-  Template.register_tag('echo'.freeze, Echo)
-end

lib/liquid/tags/for.rb

@@ -70,16 +70,14 @@ module Liquid
       @else_block = BlockBody.new
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       segment = collection_segment(context)
 
       if segment.empty?
-        render_else(context, output)
+        render_else(context)
       else
-        render_segment(context, output, segment)
+        render_segment(context, segment)
       end
-
-      output
     end
 
     protected
@@ -135,7 +133,6 @@ module Liquid
       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?
@@ -147,14 +144,16 @@ module Liquid
       segment = Utils.slice_collection(collection, from, to)
       segment.reverse! if @reversed
 
-      offsets[@name] = from + segment.length
+      offsets[@name] = from + segment.size
 
       segment
     end
 
-    def render_segment(context, output, segment)
+    def render_segment(context, segment)
       for_stack = context.registers[:for_stack] ||= []
-      length = segment.length
+      length = segment.size
+
+      result = ''
 
       context.stack do
         loop_vars = Liquid::ForloopDrop.new(@name, length, for_stack[-1])
@@ -166,7 +165,7 @@ module Liquid
 
           segment.each do |item|
             context[@variable_name] = item
-            @for_block.render_to_output_buffer(context, output)
+            result << @for_block.render(context)
             loop_vars.send(:increment!)
 
             # Handle any interrupts if they exist.
@@ -181,7 +180,7 @@ module Liquid
         end
       end
 
-      output
+      result
     end
 
     def set_attribute(key, expr)
@@ -197,12 +196,8 @@ module Liquid
       end
     end
 
-    def render_else(context, output)
+    def render_else(context)
-      if @else_block
+      @else_block ? @else_block.render(context) : ''.freeze
-        @else_block.render_to_output_buffer(context, output)
-      else
-        output
-      end
     end
 
     class ParseTreeVisitor < Liquid::ParseTreeVisitor

lib/liquid/tags/if.rb

@@ -39,16 +39,15 @@ module Liquid
       end
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       context.stack do
         @blocks.each do |block|
           if block.evaluate(context)
-            return block.attachment.render_to_output_buffer(context, output)
+            return block.attachment.render(context)
           end
         end
+        ''.freeze
       end
-
-      output
     end
 
     private

lib/liquid/tags/ifchanged.rb

@@ -1,17 +1,16 @@
 module Liquid
   class Ifchanged < Block
-    def render_to_output_buffer(context, output)
+    def render(context)
       context.stack do
-        block_output = ''
+        output = super
-        super(context, block_output)
 
-        if block_output != context.registers[:ifchanged]
+        if output != context.registers[:ifchanged]
-          context.registers[:ifchanged] = block_output
+          context.registers[:ifchanged] = output
-          output << block_output
+          output
+        else
+          ''.freeze
         end
       end
-
-      output
     end
   end
 

lib/liquid/tags/include.rb

@@ -42,16 +42,11 @@ module Liquid
     def parse(_tokens)
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       template_name = context.evaluate(@template_name_expr)
       raise ArgumentError.new(options[:locale].t("errors.argument.include")) unless template_name
 
-      partial = PartialCache.load(
+      partial = load_cached_partial(template_name, context)
-        template_name,
-        context: context,
-        parse_context: parse_context
-      )
-
       context_variable_name = template_name.split('/'.freeze).last
 
       variable = if @variable_name_expr
@@ -71,26 +66,50 @@ module Liquid
           end
 
           if variable.is_a?(Array)
-            variable.each do |var|
+            variable.collect do |var|
               context[context_variable_name] = var
-              partial.render_to_output_buffer(context, output)
+              partial.render(context)
             end
           else
             context[context_variable_name] = variable
-            partial.render_to_output_buffer(context, output)
+            partial.render(context)
           end
         end
       ensure
         context.template_name = old_template_name
         context.partial = old_partial
       end
-
-      output
     end
 
+    private
+
     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
+      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
         [

lib/liquid/tags/increment.rb

@@ -20,12 +20,10 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       value = context.environments.first[@variable] ||= 0
       context.environments.first[@variable] = value + 1
-
+      value.to_s
-      output << value.to_s
-      output
     end
   end
 

lib/liquid/tags/raw.rb

@@ -22,9 +22,8 @@ module Liquid
       raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name))
     end
 
-    def render_to_output_buffer(_context, output)
+    def render(_context)
-      output << @body
+      @body
-      output
     end
 
     def nodelist

lib/liquid/tags/render.rb

@@ -1,54 +0,0 @@
-module Liquid
-  class Render < Tag
-    SYNTAX = /(#{QuotedString})#{QuotedFragment}*/o
-
-    attr_reader :template_name_expr, :attributes
-
-    def initialize(tag_name, markup, options)
-      super
-
-      raise SyntaxError.new(options[:locale].t("errors.syntax.render".freeze)) unless markup =~ SYNTAX
-
-      template_name = $1
-
-      @template_name_expr = Expression.parse(template_name)
-
-      @attributes = {}
-      markup.scan(TagAttributes) do |key, value|
-        @attributes[key] = Expression.parse(value)
-      end
-    end
-
-    def render_to_output_buffer(context, output)
-      # Though we evaluate this here we will only ever parse it as a string literal.
-      template_name = context.evaluate(@template_name_expr)
-      raise ArgumentError.new(options[:locale].t("errors.argument.include")) unless template_name
-
-      partial = PartialCache.load(
-        template_name,
-        context: context,
-        parse_context: parse_context
-      )
-
-      inner_context = context.new_isolated_subcontext
-      inner_context.template_name = template_name
-      inner_context.partial = true
-      @attributes.each do |key, value|
-        inner_context[key] = context.evaluate(value)
-      end
-      partial.render_to_output_buffer(inner_context, output)
-
-      output
-    end
-
-    class ParseTreeVisitor < Liquid::ParseTreeVisitor
-      def children
-        [
-          @node.template_name_expr,
-        ] + @node.attributes.values
-      end
-    end
-  end
-
-  Template.register_tag('render'.freeze, Render)
-end

lib/liquid/tags/table_row.rb

@@ -18,7 +18,7 @@ module Liquid
       end
     end
 
-    def render_to_output_buffer(context, output)
+    def render(context)
       collection = context.evaluate(@collection_name) or return ''.freeze
 
       from = @attributes.key?('offset'.freeze) ? context.evaluate(@attributes['offset'.freeze]).to_i : 0
@@ -30,7 +30,7 @@ module Liquid
 
       cols = context.evaluate(@attributes['cols'.freeze]).to_i
 
-      output << "<tr class=\"row1\">\n"
+      result = "<tr class=\"row1\">\n"
       context.stack do
         tablerowloop = Liquid::TablerowloopDrop.new(length, cols)
         context['tablerowloop'.freeze] = tablerowloop
@@ -38,20 +38,17 @@ module Liquid
         collection.each do |item|
           context[@variable_name] = item
 
-          output << "<td class=\"col#{tablerowloop.col}\">"
+          result << "<td class=\"col#{tablerowloop.col}\">" << super << '</td>'
-          super
-          output << '</td>'
 
           if tablerowloop.col_last && !tablerowloop.last
-            output << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
+            result << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
           end
 
           tablerowloop.send(:increment!)
         end
       end
-
+      result << "</tr>\n"
-      output << "</tr>\n"
+      result
-      output
     end
 
     class ParseTreeVisitor < Liquid::ParseTreeVisitor

lib/liquid/tags/unless.rb

@@ -6,23 +6,23 @@ module Liquid
   #   {% unless x < 0 %} x is greater than zero {% endunless %}
   #
   class Unless < If
-    def render_to_output_buffer(context, output)
+    def render(context)
       context.stack do
         # First condition is interpreted backwards ( if not )
         first_block = @blocks.first
         unless first_block.evaluate(context)
-          return first_block.attachment.render_to_output_buffer(context, output)
+          return first_block.attachment.render(context)
         end
 
         # After the first condition unless works just like if
         @blocks[1..-1].each do |block|
           if block.evaluate(context)
-            return block.attachment.render_to_output_buffer(context, output)
+            return block.attachment.render(context)
           end
         end
-      end
 
-      output
+        ''.freeze
+      end
     end
   end
 

lib/liquid/template.rb

@@ -50,7 +50,7 @@ module Liquid
       private
 
       def lookup_class(name)
-        Object.const_get(name)
+        name.split("::").reject(&:empty?).reduce(Object) { |scope, const| scope.const_get(const) }
       end
     end
 
@@ -187,12 +187,9 @@ module Liquid
         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]
 
         registers.merge!(options[:registers]) if options[:registers].is_a?(Hash)
 
@@ -207,9 +204,10 @@ module Liquid
       begin
         # render the nodelist.
         # for performance reasons we get an array back here. join will make a string out of it.
-        with_profiling(context) do
+        result = with_profiling(context) do
-          @root.render_to_output_buffer(context, output || '')
+          @root.render(context)
         end
+        result.respond_to?(:join) ? result.join : result
       rescue Liquid::MemoryError => e
         context.handle_error(e)
       ensure
@@ -222,10 +220,6 @@ module Liquid
       render(*args)
     end
 
-    def render_to_output_buffer(context, output)
-      render(context, output: output)
-    end
-
     private
 
     def tokenize(source)

lib/liquid/tokenizer.rb

@@ -1,31 +1,25 @@
 module Liquid
   class Tokenizer
-    attr_reader :line_number, :for_liquid_tag
+    attr_reader :line_number
 
-    def initialize(source, line_numbers = false, line_number: nil, for_liquid_tag: false)
+    def initialize(source, line_numbers = false)
       @source = source
-      @line_number = line_number || (line_numbers ? 1 : nil)
+      @line_number = line_numbers ? 1 : nil
-      @for_liquid_tag = for_liquid_tag
       @tokens = tokenize
     end
 
     def shift
-      token = @tokens.shift or return
+      token = @tokens.shift
-
+      @line_number += token.count("\n") if @line_number && token
-      if @line_number
-        @line_number += @for_liquid_tag ? 1 : token.count("\n")
-      end
-
       token
     end
 
     private
 
     def tokenize
+      @source = @source.source if @source.respond_to?(:source)
       return [] if @source.to_s.empty?
 
-      return @source.split("\n") if @for_liquid_tag
-
       tokens = @source.split(TemplateParser)
 
       # removes the rogue empty element at the beginning of the array

lib/liquid/usage.rb

@@ -1,6 +0,0 @@
-module Liquid
-  module Usage
-    def self.increment(name)
-    end
-  end
-end

lib/liquid/utils.rb

@@ -1,6 +1,8 @@
 module Liquid
   module Utils
     def self.slice_collection(collection, from, to)
+      return collection.load_slice(from, to) if collection.is_a?(ReversableRange)
+
       if (from != 0 || !to.nil?) && collection.respond_to?(:load_slice)
         collection.load_slice(from, to)
       else

lib/liquid/variable.rb

@@ -85,23 +85,12 @@ module Liquid
       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)

liquid.gemspec

@@ -16,7 +16,7 @@ Gem::Specification.new do |s|
   s.license     = "MIT"
   # s.description = "A secure, non-evaling end user template engine with aesthetic markup."
 
-  s.required_ruby_version     = ">= 2.4.0"
+  s.required_ruby_version     = ">= 2.1.0"
   s.required_rubygems_version = ">= 1.3.7"
 
   s.test_files  = Dir.glob("{test}/**/*")

performance/memory_profile.rb

@@ -2,62 +2,25 @@
 
 require 'benchmark/ips'
 require 'memory_profiler'
-require 'terminal-table'
 require_relative 'theme_runner'
 
-class Profiler
+def profile(phase, &block)
-  LOG_LABEL   = "Profiling: ".rjust(14).freeze
+  puts
-  REPORTS_DIR = File.expand_path('.memprof', __dir__).freeze
+  puts "#{phase}:"
+  puts
 
-  def self.run
+  report = MemoryProfiler.report(&block)
-    puts
-    yield new
-  end
 
-  def initialize
+  report.pretty_print(
-    @allocated = []
+    color_output: true,
-    @retained  = []
+    scale_bytes: true,
-    @headings  = []
+    detailed_report: true
-  end
+  )
-
-  def profile(phase, &block)
-    print LOG_LABEL
-    print "#{phase}.. ".ljust(10)
-    report = MemoryProfiler.report(&block)
-    puts 'Done.'
-    @headings  << phase.capitalize
-    @allocated << "#{report.scale_bytes(report.total_allocated_memsize)} (#{report.total_allocated} objects)"
-    @retained  << "#{report.scale_bytes(report.total_retained_memsize)} (#{report.total_retained} objects)"
-
-    return if ENV['CI']
-
-    require 'fileutils'
-    report_file = File.join(REPORTS_DIR, "#{sanitize(phase)}.txt")
-    FileUtils.mkdir_p(REPORTS_DIR)
-    report.pretty_print(to_file: report_file, scale_bytes: true)
-  end
-
-  def tabulate
-    table = Terminal::Table.new(headings: @headings.unshift('Phase')) do |t|
-      t << @allocated.unshift('Total allocated')
-      t << @retained.unshift('Total retained')
-    end
-
-    puts
-    puts table
-    puts "\nDetailed report(s) saved to #{REPORTS_DIR}/" unless ENV['CI']
-  end
-
-  def sanitize(string)
-    string.downcase.gsub(/[\W]/, '-').squeeze('-')
-  end
 end
 
 Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
 
-runner = ThemeRunner.new
+profiler = ThemeRunner.new
-Profiler.run do |x|
+
-  x.profile('parse') { runner.compile }
+profile("Parsing") { profiler.compile }
-  x.profile('render') { runner.render }
+profile("Rendering") { profiler.render }
-  x.tabulate
-end

performance/shopify/comment_form.rb

@@ -12,7 +12,7 @@ class CommentForm < Liquid::Block
     end
   end
 
-  def render_to_output_buffer(context, output)
+  def render(context)
     article = context[@variable_name]
 
     context.stack do
@@ -23,9 +23,7 @@ class CommentForm < Liquid::Block
         '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
 

performance/shopify/paginate.rb

@@ -21,7 +21,7 @@ class Paginate < Liquid::Block
     end
   end
 
-  def render_to_output_buffer(context, output)
+  def render(context)
     @context = context
 
     context.stack do

test/integration/blank_test.rb

@@ -1,10 +1,11 @@
 require 'test_helper'
 
 class FoobarTag < Liquid::Tag
-  def render_to_output_buffer(context, output)
+  def render(*args)
-    output << ' '
+    " "
-    output
   end
+
+  Liquid::Template.register_tag('foobar', FoobarTag)
 end
 
 class BlankTestFileSystem
@@ -30,9 +31,7 @@ class BlankTest < Minitest::Test
   end
 
   def test_new_tags_are_not_blank_by_default
-    with_custom_tag('foobar', FoobarTag) do
+    assert_template_result(" " * N, wrap_in_for("{% foobar %}"))
-      assert_template_result(" " * N, wrap_in_for("{% foobar %}"))
-    end
   end
 
   def test_loops_are_blank

test/integration/tags/echo_test.rb

@@ -1,11 +0,0 @@
-require 'test_helper'
-
-class EchoTest < Minitest::Test
-  include Liquid
-
-  def test_echo_outputs_its_input
-    assert_template_result('BAR', <<~LIQUID, { 'variable-name' => 'bar' })
-      {%- echo variable-name | upcase -%}
-    LIQUID
-  end
-end

test/integration/tags/for_tag_test.rb

@@ -36,6 +36,10 @@ HERE
     assert_template_result('321', '{%for item in array reversed %}{{item}}{%endfor%}', assigns)
   end
 
+  def test_for_range_reversed
+    assert_template_result('321', '{%for item in (1..3) reversed %}{{item}}{%endfor%}', {})
+  end
+
   def test_for_with_range
     assert_template_result(' 1  2  3 ', '{%for item in (1..3) %} {{item}} {%endfor%}')
 

test/integration/tags/include_tag_test.rb

@@ -66,9 +66,8 @@ class CustomInclude < Liquid::Tag
   def parse(tokens)
   end
 
-  def render_to_output_buffer(context, output)
+  def render(context)
-    output << @template_name[1..-2]
+    @template_name[1..-2]
-    output
   end
 end
 

test/integration/tags/liquid_tag_test.rb

@@ -1,104 +0,0 @@
-require 'test_helper'
-
-class LiquidTagTest < Minitest::Test
-  include Liquid
-
-  def test_liquid_tag
-    assert_template_result('1 2 3', <<~LIQUID, 'array' => [1, 2, 3])
-      {%- liquid
-        echo array | join: " "
-      -%}
-    LIQUID
-
-    assert_template_result('1 2 3', <<~LIQUID, 'array' => [1, 2, 3])
-      {%- liquid
-        for value in array
-          echo value
-          unless forloop.last
-            echo " "
-          endunless
-        endfor
-      -%}
-    LIQUID
-
-    assert_template_result('4 8 12 6', <<~LIQUID, 'array' => [1, 2, 3])
-      {%- liquid
-        for value in array
-          assign double_value = value | times: 2
-          echo double_value | times: 2
-          unless forloop.last
-            echo " "
-          endunless
-        endfor
-
-        echo " "
-        echo double_value
-      -%}
-    LIQUID
-
-    assert_template_result('abc', <<~LIQUID)
-      {%- liquid echo "a" -%}
-      b
-      {%- liquid echo "c" -%}
-    LIQUID
-  end
-
-  def test_liquid_tag_errors
-    assert_match_syntax_error("syntax error (line 1): Unknown tag 'error'", <<~LIQUID)
-      {%- liquid error no such tag -%}
-    LIQUID
-
-    assert_match_syntax_error("syntax error (line 7): Unknown tag 'error'", <<~LIQUID)
-      {{ test }}
-
-      {%-
-      liquid
-        for value in array
-
-          error no such tag
-        endfor
-      -%}
-    LIQUID
-
-    assert_match_syntax_error("syntax error (line 2): Unknown tag '!!! the guards are vigilant'", <<~LIQUID)
-      {%- liquid
-        !!! the guards are vigilant
-      -%}
-    LIQUID
-
-    assert_match_syntax_error("syntax error (line 4): 'for' tag was never closed", <<~LIQUID)
-      {%- liquid
-        for value in array
-          echo 'forgot to close the for tag'
-      -%}
-    LIQUID
-  end
-
-  def test_line_number_is_correct_after_a_blank_token
-    assert_match_syntax_error("syntax error (line 3): Unknown tag 'error'", "{% liquid echo ''\n\n error %}")
-    assert_match_syntax_error("syntax error (line 3): Unknown tag 'error'", "{% liquid echo ''\n  \n error %}")
-  end
-
-  def test_cannot_open_blocks_living_past_a_liquid_tag
-    assert_match_syntax_error("syntax error (line 3): 'if' tag was never closed", <<~LIQUID)
-      {%- liquid
-        if true
-      -%}
-      {%- endif -%}
-    LIQUID
-  end
-
-  def test_quirk_can_close_blocks_created_before_a_liquid_tag
-    assert_template_result("42", <<~LIQUID)
-      {%- if true -%}
-      42
-      {%- liquid endif -%}
-    LIQUID
-  end
-
-  def test_liquid_tag_in_raw
-    assert_template_result("{% liquid echo 'test' %}\n", <<~LIQUID)
-      {% raw %}{% liquid echo 'test' %}{% endraw %}
-    LIQUID
-  end
-end

test/integration/tags/render_tag_test.rb

@@ -1,149 +0,0 @@
-require 'test_helper'
-
-class RenderTagTest < Minitest::Test
-  include Liquid
-
-  def test_render_with_no_arguments
-    Liquid::Template.file_system = StubFileSystem.new('source' => 'rendered content')
-    assert_template_result 'rendered content', '{% render "source" %}'
-  end
-
-  def test_render_tag_looks_for_file_system_in_registers_first
-    file_system = StubFileSystem.new('pick_a_source' => 'from register file system')
-    assert_equal 'from register file system',
-      Template.parse('{% render "pick_a_source" %}').render!({}, registers: { file_system: file_system })
-  end
-
-  def test_render_passes_named_arguments_into_inner_scope
-    Liquid::Template.file_system = StubFileSystem.new('product' => '{{ inner_product.title }}')
-    assert_template_result 'My Product', '{% render "product", inner_product: outer_product %}',
-      'outer_product' => { 'title' => 'My Product' }
-  end
-
-  def test_render_accepts_literals_as_arguments
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ price }}')
-    assert_template_result '123', '{% render "snippet", price: 123 %}'
-  end
-
-  def test_render_accepts_multiple_named_arguments
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ one }} {{ two }}')
-    assert_template_result '1 2', '{% render "snippet", one: 1, two: 2 %}'
-  end
-
-  def test_render_does_not_inherit_parent_scope_variables
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ outer_variable }}')
-    assert_template_result '', '{% assign outer_variable = "should not be visible" %}{% render "snippet" %}'
-  end
-
-  def test_render_does_not_inherit_variable_with_same_name_as_snippet
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ snippet }}')
-    assert_template_result '', "{% assign snippet = 'should not be visible' %}{% render 'snippet' %}"
-  end
-
-  def test_render_sets_the_correct_template_name_for_errors
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ unsafe }}')
-
-    with_taint_mode :error do
-      template = Liquid::Template.parse('{% render "snippet", unsafe: unsafe %}')
-      context = Context.new('unsafe' => (+'unsafe').tap(&:taint))
-      template.render(context)
-
-      assert_equal [Liquid::TaintedError], template.errors.map(&:class)
-      assert_equal 'snippet', template.errors.first.template_name
-    end
-  end
-
-  def test_render_sets_the_correct_template_name_for_warnings
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{{ unsafe }}')
-
-    with_taint_mode :warn do
-      template = Liquid::Template.parse('{% render "snippet", unsafe: unsafe %}')
-      context = Context.new('unsafe' => (+'unsafe').tap(&:taint))
-      template.render(context)
-
-      assert_equal [Liquid::TaintedError], context.warnings.map(&:class)
-      assert_equal 'snippet', context.warnings.first.template_name
-    end
-  end
-
-  def test_render_does_not_mutate_parent_scope
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => '{% assign inner = 1 %}')
-    assert_template_result '', "{% render 'snippet' %}{{ inner }}"
-  end
-
-  def test_nested_render_tag
-    Liquid::Template.file_system = StubFileSystem.new(
-      'one' => "one {% render 'two' %}",
-      'two' => 'two'
-    )
-    assert_template_result 'one two', "{% render 'one' %}"
-  end
-
-  def test_recursively_rendered_template_does_not_produce_endless_loop
-    Liquid::Template.file_system = StubFileSystem.new('loop' => '{% render "loop" %}')
-
-    assert_raises Liquid::StackLevelError do
-      Template.parse('{% render "loop" %}').render!
-    end
-  end
-
-  def test_includes_and_renders_count_towards_the_same_recursion_limit
-    Liquid::Template.file_system = StubFileSystem.new(
-      'loop_render' => '{% render "loop_include" %}',
-      'loop_include' => '{% include "loop_render" %}'
-    )
-
-    assert_raises Liquid::StackLevelError  do
-      Template.parse('{% render "loop_include" %}').render!
-    end
-  end
-
-  def test_dynamically_choosen_templates_are_not_allowed
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => 'should not be rendered')
-
-    assert_raises Liquid::SyntaxError do
-      Liquid::Template.parse("{% assign name = 'snippet' %}{% render name %}")
-    end
-  end
-
-  def test_include_tag_caches_second_read_of_same_partial
-    file_system = StubFileSystem.new('snippet' => 'echo')
-    assert_equal 'echoecho',
-      Template.parse('{% render "snippet" %}{% render "snippet" %}')
-      .render!({}, registers: { file_system: file_system })
-    assert_equal 1, file_system.file_read_count
-  end
-
-  def test_render_tag_doesnt_cache_partials_across_renders
-    file_system = StubFileSystem.new('snippet' => 'my message')
-
-    assert_equal 'my message',
-      Template.parse('{% include "snippet" %}').render!({}, registers: { file_system: file_system })
-    assert_equal 1, file_system.file_read_count
-
-    assert_equal 'my message',
-      Template.parse('{% include "snippet" %}').render!({}, registers: { file_system: file_system })
-    assert_equal 2, file_system.file_read_count
-  end
-
-  def test_render_tag_within_if_statement
-    Liquid::Template.file_system = StubFileSystem.new('snippet' => 'my message')
-    assert_template_result 'my message', '{% if true %}{% render "snippet" %}{% endif %}'
-  end
-
-  def test_break_through_render
-    Liquid::Template.file_system = StubFileSystem.new('break' => '{% break %}')
-    assert_template_result '1', '{% for i in (1..3) %}{{ i }}{% break %}{{ i }}{% endfor %}'
-    assert_template_result '112233', '{% for i in (1..3) %}{{ i }}{% render "break" %}{{ i }}{% endfor %}'
-  end
-
-  def test_increment_is_isolated_between_renders
-    Liquid::Template.file_system = StubFileSystem.new('incr' => '{% increment %}')
-    assert_template_result '010', '{% increment %}{% increment %}{% render "incr" %}'
-  end
-
-  def test_decrement_is_isolated_between_renders
-    Liquid::Template.file_system = StubFileSystem.new('decr' => '{% decrement %}')
-    assert_template_result '-1-2-1', '{% decrement %}{% decrement %}{% render "decr" %}'
-  end
-end

test/test_helper.rb

@@ -14,7 +14,7 @@ if env_mode = ENV['LIQUID_PARSER_MODE']
 end
 Liquid::Template.error_mode = mode
 
-if ENV['LIQUID_C'] == '1'
+if ENV['LIQUID-C'] == '1'
   puts "-- LIQUID C"
   require 'liquid/c'
 end
@@ -37,18 +37,18 @@ module Minitest
     include Liquid
 
     def assert_template_result(expected, template, assigns = {}, message = nil)
-      assert_equal expected, Template.parse(template, line_numbers: true).render!(assigns), message
+      assert_equal expected, Template.parse(template).render!(assigns), message
     end
 
     def assert_template_result_matches(expected, template, assigns = {}, message = nil)
       return assert_template_result(expected, template, assigns, message) unless expected.is_a? Regexp
 
-      assert_match expected, Template.parse(template, line_numbers: true).render!(assigns), message
+      assert_match expected, Template.parse(template).render!(assigns), message
     end
 
     def assert_match_syntax_error(match, template, assigns = {})
       exception = assert_raises(Liquid::SyntaxError) do
-        Template.parse(template, line_numbers: true).render(assigns)
+        Template.parse(template).render(assigns)
       end
       assert_match match, exception.message
     end
@@ -84,13 +84,6 @@ module Minitest
     ensure
       Liquid::Template.error_mode = old_mode
     end
-
-    def with_custom_tag(tag_name, tag_class)
-      Liquid::Template.register_tag(tag_name, tag_class)
-      yield
-    ensure
-      Liquid::Template.tags.delete(tag_name)
-    end
   end
 end
 
@@ -121,17 +114,3 @@ class ErrorDrop < Liquid::Drop
     raise Exception, 'exception'
   end
 end
-
-class StubFileSystem
-  attr_reader :file_read_count
-
-  def initialize(values)
-    @file_read_count = 0
-    @values = values
-  end
-
-  def read_template_file(template_path)
-    @file_read_count += 1
-    @values.fetch(template_path)
-  end
-end

test/unit/block_unit_test.rb

@@ -44,47 +44,10 @@ class BlockUnitTest < Minitest::Test
   end
 
   def test_with_custom_tag
-    with_custom_tag('testtag', Block) do
+    Liquid::Template.register_tag("testtag", Block)
-      assert Liquid::Template.parse("{% testtag %} {% endtesttag %}")
+    assert Liquid::Template.parse("{% testtag %} {% endtesttag %}")
-    end
+  ensure
-  end
+    Liquid::Template.tags.delete('testtag')
-
-  def test_custom_block_tags_have_a_default_render_to_output_buffer_method_for_backwards_compatibility
-    klass1 = Class.new(Block) do
-      def render(*)
-        'hello'
-      end
-    end
-
-    with_custom_tag('blabla', klass1) do
-      template = Liquid::Template.parse("{% blabla %} bla {% endblabla %}")
-
-      assert_equal 'hello', template.render
-
-      buf = ''
-      output = template.render({}, output: buf)
-      assert_equal 'hello', output
-      assert_equal 'hello', buf
-      assert_equal buf.object_id, output.object_id
-    end
-
-    klass2 = Class.new(klass1) do
-      def render(*)
-        'foo' + super + 'bar'
-      end
-    end
-
-    with_custom_tag('blabla', klass2) do
-      template = Liquid::Template.parse("{% blabla %} foo {% endblabla %}")
-
-      assert_equal 'foohellobar', template.render
-
-      buf = ''
-      output = template.render({}, output: buf)
-      assert_equal 'foohellobar', output
-      assert_equal 'foohellobar', buf
-      assert_equal buf.object_id, output.object_id
-    end
   end
 
   private

test/unit/context_unit_test.rb

@@ -349,9 +349,9 @@ class ContextUnitTest < Minitest::Test
 
   def test_ranges
     @context.merge("test" => '5')
-    assert_equal (1..5), @context['(1..5)']
+    assert_equal ReversableRange.new(1, 5), @context['(1..5)']
-    assert_equal (1..5), @context['(1..test)']
+    assert_equal ReversableRange.new(1, 5), @context['(1..test)']
-    assert_equal (5..5), @context['(test..test)']
+    assert_equal ReversableRange.new(5, 5), @context['(test..test)']
   end
 
   def test_cents_through_drop_nestedly
@@ -468,79 +468,11 @@ class ContextUnitTest < Minitest::Test
     assert_equal 'hi filtered', context.apply_global_filter('hi')
   end
 
-  def test_static_environments_are_read_with_lower_priority_than_environments
-    context = Context.build(
-      static_environments: { 'shadowed' => 'static', 'unshadowed' => 'static' },
-      environments: { 'shadowed' => 'dynamic' }
-    )
-
-    assert_equal 'dynamic', context['shadowed']
-    assert_equal 'static', context['unshadowed']
-  end
-
   def test_apply_global_filter_when_no_global_filter_exist
     context = Context.new
     assert_equal 'hi', context.apply_global_filter('hi')
   end
 
-  def test_new_isolated_subcontext_does_not_inherit_variables
-    super_context = Context.new
-    super_context['my_variable'] = 'some value'
-    subcontext = super_context.new_isolated_subcontext
-
-    assert_nil subcontext['my_variable']
-  end
-
-  def test_new_isolated_subcontext_inherits_static_environment
-    super_context = Context.build(static_environments: { 'my_environment_value' => 'my value' })
-    subcontext = super_context.new_isolated_subcontext
-
-    assert_equal 'my value', subcontext['my_environment_value']
-  end
-
-  def test_new_isolated_subcontext_inherits_resource_limits
-    resource_limits = ResourceLimits.new({})
-    super_context = Context.new({}, {}, {}, false, resource_limits)
-    subcontext = super_context.new_isolated_subcontext
-    assert_equal resource_limits, subcontext.resource_limits
-  end
-
-  def test_new_isolated_subcontext_inherits_exception_renderer
-    super_context = Context.new
-    super_context.exception_renderer = ->(_e) { 'my exception message' }
-    subcontext = super_context.new_isolated_subcontext
-    assert_equal 'my exception message', subcontext.handle_error(Liquid::Error.new)
-  end
-
-  def test_new_isolated_subcontext_does_not_inherit_non_static_registers
-    registers = {
-      my_register: :my_value
-    }
-    super_context = Context.new({}, {}, registers)
-    subcontext = super_context.new_isolated_subcontext
-    assert_nil subcontext.registers[:my_register]
-  end
-
-  def test_new_isolated_subcontext_inherits_static_registers
-    super_context = Context.build(static_registers: { my_register: :my_value })
-    subcontext = super_context.new_isolated_subcontext
-    assert_equal :my_value, subcontext.static_registers[:my_register]
-  end
-
-  def test_new_isolated_subcontext_inherits_filters
-    my_filter = Module.new do
-      def my_filter(*)
-        'my filter result'
-      end
-    end
-
-    super_context = Context.new
-    super_context.add_filters([my_filter])
-    subcontext = super_context.new_isolated_subcontext
-    template = Template.parse('{{ 123 | my_filter }}')
-    assert_equal 'my filter result', template.render(subcontext)
-  end
-
   private
 
   def assert_no_object_allocations

test/unit/partial_cache_unit_test.rb

@@ -1,91 +0,0 @@
-require 'test_helper'
-
-class PartialCacheUnitTest < Minitest::Test
-  def test_uses_the_file_system_register_if_present
-    context = Liquid::Context.build(
-      registers: {
-        file_system: StubFileSystem.new('my_partial' => 'my partial body'),
-      }
-    )
-
-    partial = Liquid::PartialCache.load(
-      'my_partial',
-      context: context,
-      parse_context: Liquid::ParseContext.new
-    )
-
-    assert_equal 'my partial body', partial.render
-  end
-
-  def test_reads_from_the_file_system_only_once_per_file
-    file_system = StubFileSystem.new('my_partial' => 'some partial body')
-    context = Liquid::Context.build(
-      registers: { file_system: file_system }
-    )
-
-    2.times do
-      Liquid::PartialCache.load(
-        'my_partial',
-        context: context,
-        parse_context: Liquid::ParseContext.new
-      )
-    end
-
-    assert_equal 1, file_system.file_read_count
-  end
-
-  def test_cache_state_is_stored_per_context
-    parse_context = Liquid::ParseContext.new
-    shared_file_system = StubFileSystem.new(
-      'my_partial' => 'my shared value'
-    )
-    context_one = Liquid::Context.build(
-      registers: {
-        file_system: shared_file_system,
-      }
-    )
-    context_two = Liquid::Context.build(
-      registers: {
-        file_system: shared_file_system,
-      }
-    )
-
-    2.times do
-      Liquid::PartialCache.load(
-        'my_partial',
-        context: context_one,
-        parse_context: parse_context
-      )
-    end
-
-    Liquid::PartialCache.load(
-      'my_partial',
-      context: context_two,
-      parse_context: parse_context
-    )
-
-    assert_equal 2, shared_file_system.file_read_count
-  end
-
-  def test_cache_is_not_broken_when_a_different_parse_context_is_used
-    file_system = StubFileSystem.new('my_partial' => 'some partial body')
-    context = Liquid::Context.build(
-      registers: { file_system: file_system }
-    )
-
-    Liquid::PartialCache.load(
-      'my_partial',
-      context: context,
-      parse_context: Liquid::ParseContext.new(my_key: 'value one')
-    )
-    Liquid::PartialCache.load(
-      'my_partial',
-      context: context,
-      parse_context: Liquid::ParseContext.new(my_key: 'value two')
-    )
-
-    # Technically what we care about is that the file was parsed twice,
-    # but measuring file reads is an OK proxy for this.
-    assert_equal 1, file_system.file_read_count
-  end
-end

test/unit/reversable_range_unit_test.rb

@@ -0,0 +1,116 @@
+require 'test_helper'
+
+class ReversableRangeTest < Minitest::Test
+  include Liquid
+
+  def test_each_iterates_through_items_in_the_range
+    actual_items = []
+    ReversableRange.new(1, 10).each { |item| actual_items << item }
+
+    expected_items = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
+    assert_equal expected_items, actual_items
+  end
+
+  def test_implements_enumerable
+    actual_items = ReversableRange.new(1, 10).select(&:even?)
+
+    expected_items = [2, 4, 6, 8, 10]
+    assert_equal expected_items, actual_items
+  end
+
+  def test_is_not_empty_max_greater_than_min
+    range = ReversableRange.new(9, 10)
+
+    refute_predicate range, :empty?
+  end
+
+  def test_is_not_empty_max_equal_to_min
+    range = ReversableRange.new(10, 10)
+
+    refute_predicate range, :empty?
+  end
+
+  def test_is_empty_if_not_reversed_and_max_less_than_min
+    range = ReversableRange.new(10, 9)
+
+    assert_predicate range, :empty?
+  end
+
+  def test_ranges_with_the_same_max_and_min_have_one_element
+    actual_items = ReversableRange.new(1337, 1337).to_a
+    expected_items = [1337]
+    assert_equal expected_items, actual_items
+  end
+
+  def test_load_slice_returns_a_sub_range
+    actual_items = ReversableRange.new(1, 10).load_slice(5, 8).to_a
+
+    expected_items = [5, 6, 7, 8]
+    assert_equal expected_items, actual_items
+  end
+
+  def test_load_slice_returns_a_reversed_sub_range_if_reversed
+    range = ReversableRange.new(1, 10)
+    range.reverse!
+    actual_items = range.load_slice(5, 8).to_a
+
+    expected_items = [8, 7, 6, 5]
+    assert_equal expected_items, actual_items
+  end
+
+  def test_is_equal_to_other_if_also_a_reversable_range_and_has_same_properties
+    one = ReversableRange.new(1, 10)
+    one.reverse!
+
+    two = ReversableRange.new(1, 10)
+    two.reverse!
+
+    assert_equal one, two
+  end
+
+  def test_is_not_equal_to_a_non_reversable_range
+    range = ReversableRange.new(1, 10)
+    range.reverse!
+
+    refute_equal range, :something_else
+  end
+
+  def test_is_not_equal_if_ranges_have_different_mins
+    one = ReversableRange.new(1, 10)
+    two = ReversableRange.new(2, 10)
+
+    refute_equal one, two
+  end
+
+  def test_is_not_equal_if_ranges_have_different_maxes
+    one = ReversableRange.new(1, 10)
+    two = ReversableRange.new(1, 11)
+
+    refute_equal one, two
+  end
+
+  def test_is_not_equal_if_only_one_is_reversed
+    one = ReversableRange.new(1, 10)
+
+    two = ReversableRange.new(1, 10)
+    two.reverse!
+
+    refute_equal one, two
+  end
+
+  def test_to_s_mirrors_rubys_range_syntax
+    range = ReversableRange.new(1, 10)
+    assert_equal '1..10', range.to_s
+  end
+
+  def test_to_s_reverses_when_reversed
+    range = ReversableRange.new(1, 10)
+    range.reverse!
+    assert_equal '10..1', range.to_s
+  end
+
+  def test_size
+    range = ReversableRange.new(1, 10)
+    assert_equal 10, range.size
+  end
+end

test/unit/tag_unit_test.rb

@@ -18,42 +18,4 @@ class TagUnitTest < Minitest::Test
     tag = Tag.parse("some_tag", "", Tokenizer.new(""), ParseContext.new)
     assert_equal 'some_tag', tag.tag_name
   end
-
-  def test_custom_tags_have_a_default_render_to_output_buffer_method_for_backwards_compatibility
-    klass1 = Class.new(Tag) do
-      def render(*)
-        'hello'
-      end
-    end
-
-    with_custom_tag('blabla', klass1) do
-      template = Liquid::Template.parse("{% blabla %}")
-
-      assert_equal 'hello', template.render
-
-      buf = ''
-      output = template.render({}, output: buf)
-      assert_equal 'hello', output
-      assert_equal 'hello', buf
-      assert_equal buf.object_id, output.object_id
-    end
-
-    klass2 = Class.new(klass1) do
-      def render(*)
-        'foo' + super + 'bar'
-      end
-    end
-
-    with_custom_tag('blabla', klass2) do
-      template = Liquid::Template.parse("{% blabla %}")
-
-      assert_equal 'foohellobar', template.render
-
-      buf = ''
-      output = template.render({}, output: buf)
-      assert_equal 'foohellobar', output
-      assert_equal 'foohellobar', buf
-      assert_equal buf.object_id, output.object_id
-    end
-  end
 end