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
-
-require: rubocop-performance
-
-Performance:
-  Enabled: true
+  - ./.rubocop_todo.yml
 
 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.
-# SupportedHashRocketStyles: key, separator, table
-# SupportedColonStyles: key, separator, table
-# SupportedLastArgumentHashStyles: always_inspect, always_ignore, ignore_implicit, ignore_explicit
-Layout/AlignHash:
+# Configuration parameters: Include, TreatCommentsAsGroupSeparators.
+# Include: **/*.gemspec
+Gemspec/OrderedDependencies:
   Exclude:
-    - 'lib/liquid/condition.rb'
-    - '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'
+    - 'liquid.gemspec'
 
 # 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
-# Cop supports --auto-correct.
-# Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
-# URISchemes: http, https
-Metrics/LineLength:
-  Max: 294
+# Offense count: 54
+Metrics/AbcSize:
+  Max: 56
 
-# Offense count: 44
-Naming/ConstantName:
+# Offense count: 12
+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'
-    - 'lib/liquid/block_body.rb'
-    - 'lib/liquid/tags/assign.rb'
-    - 'lib/liquid/tags/capture.rb'
-    - 'lib/liquid/tags/case.rb'
-    - 'lib/liquid/tags/cycle.rb'
-    - 'lib/liquid/tags/for.rb'
+    - 'test/integration/assign_test.rb'
+    - 'test/integration/capture_test.rb'
+    - 'test/integration/trim_mode_test.rb'
+
+# Offense count: 23
+# Configuration parameters: MinNameLength, AllowNamesEndingInNumbers, AllowedNames, ForbiddenNames.
+# 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/tags/raw.rb'
-    - 'lib/liquid/tags/table_row.rb'
+    - 'lib/liquid/utils.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/increment_tag_test.rb'
-    - 'test/integration/tags/standard_tag_test.rb'
+    - 'test/integration/tags/for_tag_test.rb'
     - 'test/integration/template_test.rb'
     - 'test/unit/condition_unit_test.rb'
-    - 'test/unit/context_unit_test.rb'
 
-# Offense count: 5
-Style/ClassVars:
+# Offense count: 10
+# Cop supports --auto-correct.
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: prefer_alias, prefer_alias_method
+Style/Alias:
   Exclude:
-    - 'lib/liquid/condition.rb'
-    - 'lib/liquid/strainer.rb'
-    - 'lib/liquid/template.rb'
+    - '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: 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
-Style/For:
+# SupportedStyles: compact, expanded
+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.
-# SupportedStyles: format, sprintf, percent
-Style/FormatString:
+Style/Encoding:
+  Exclude:
+    - '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
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
-# 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:
+# Offense count: 14
+# Configuration parameters: MinBodyLength.
+Style/GuardClause:
   Exclude:
-    - 'Gemfile'
-    - 'Rakefile'
-    - 'lib/liquid/block_body.rb'
-    - 'lib/liquid/parser.rb'
+    - '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'
-    - 'liquid.gemspec'
-    - 'performance/shopify/database.rb'
-    - 'performance/shopify/liquid.rb'
-    - 'test/test_helper.rb'
-    - 'test/unit/condition_unit_test.rb'
-    - 'test/unit/tags/if_tag_unit_test.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.
@@ -297,17 +188,27 @@ Style/Next:
   Exclude:
     - 'lib/liquid/tags/for.rb'
 
-# Offense count: 52
+# Offense count: 4
 # Cop supports --auto-correct.
-Style/PerlBackrefs:
-  Enabled: false
+# Configuration parameters: AutoCorrect, EnforcedStyle.
+# 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.
-# SupportedStyles: compact, exploded
-Style/RaiseArgs:
-  Enabled: false
+# 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.
@@ -315,52 +216,21 @@ Style/RedundantSelf:
   Exclude:
     - 'lib/liquid/strainer.rb'
 
-# Offense count: 5
-# 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
+# Offense count: 9
 # 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.
-# SupportedStyles: use_perl_names, use_english_names
-Style/SpecialGlobalVars:
-  Exclude:
-    - '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'
+# Configuration parameters: MinSize.
+# SupportedStyles: percent, brackets
+Style/SymbolArray:
+  EnforcedStyle: brackets
 
 # 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:
-  only:
-    - master
-    - gh-pages
-    - /.*-stable/
+install:
+  - bundle install
+
+script: bundle exec rake
 
 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-performance', require: false
+  gem 'rubocop', '~> 0.53.0'
 
-  platform :mri, :truffleruby do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'master'
+  platform :mri do
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'reversable-range'
   end
 end

Rakefile

@@ -19,10 +19,8 @@ task :warn_test do
 end
 
 task :rubocop do
-  if RUBY_ENGINE == 'ruby'
-    require 'rubocop/rake_task'
-    RuboCop::RakeTask.new
-  end
+  require 'rubocop/rake_task'
+  RuboCop::RakeTask.new
 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'
-    ENV['LIQUID_C'] = '1'
+  if RUBY_ENGINE == 'ruby'
+    ENV['LIQUID-C'] = '1'
 
     ENV['LIQUID_PARSER_MODE'] = 'lax'
     Rake::Task['base_test'].reenable

lib/liquid.rb

@@ -74,7 +74,7 @@ require 'liquid/condition'
 require 'liquid/utils'
 require 'liquid/tokenizer'
 require 'liquid/parse_context'
-require 'liquid/partial_cache'
+require 'liquid/reversable_range'
 
 # 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
-          markup = $4
-
-          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
-
+          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
@@ -113,23 +67,19 @@ module Liquid
     end
 
     def render(context)
-      render_to_output_buffer(context, '')
-    end
-
-    def render_to_output_buffer(context, output)
+      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)
-      node.render_to_output_buffer(context, output)
+    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 raise_if_resource_limits_reached(context, length)
-      context.resource_limits.render_length += length
+    def check_resources(context, node_output)
+      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 self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_registers: {}, static_environments: {})
-      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_registers, static_environments)
-    end
-
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_registers = {}, static_environments = {})
-      @environments = [environments]
-      @environments.flatten!
-
-      @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
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil)
+      @environments     = [environments].flatten
+      @scopes           = [(outer_scope || {})]
+      @registers        = registers
+      @errors           = []
+      @partial          = false
+      @strict_variables = false
+      @resource_limits  = resource_limits || ResourceLimits.new(Template.default_resource_limits)
       squash_instance_assigns_with_environments
 
       @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
-        lookup_and_evaluate(@scopes[index], key, raise_on_not_found: raise_on_not_found)
-      else
-        try_variable_find_in_environments(key, raise_on_not_found: raise_on_not_found)
+      variable = nil
+
+      if scope.nil?
+        @environments.each do |e|
+          variable = lookup_and_evaluate(e, key, raise_on_not_found: raise_on_not_found)
+          # When lookup returned a value OR there is no value but the lookup also did not raise
+          # then it is the value we are looking for.
+          if !variable.nil? || @strict_variables && raise_on_not_found
+            scope = e
+            break
+          end
+        end
       end
 
+      scope ||= @environments.last || @scopes.last
+      variable ||= lookup_and_evaluate(scope, key, raise_on_not_found: raise_on_not_found)
+
       variable = variable.to_liquid
       variable.context = self if variable.respond_to?(:context=)
 
@@ -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.rb

@@ -44,7 +44,7 @@ module Liquid
     include Enumerable
 
     class Timing
-      attr_reader :code, :partial, :line_number, :children, :total_time, :self_time
+      attr_reader :code, :partial, :line_number, :children
 
       def initialize(node, partial)
         @code        = node.respond_to?(:raw) ? node.raw : node
@@ -63,18 +63,6 @@ module Liquid
 
       def finish
         @end_time = Time.now
-        @total_time = @end_time - @start_time
-        if @children.size == 0
-          @self_time = @total_time
-        else
-          total_children_time = 0
-
-          @children.each do |child|
-            total_children_time += child.total_time
-          end
-
-          @self_time = @total_time - total_children_time
-        end
       end
 
       def render_time

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, :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
-    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_to_output_buffer, :render_to_output_buffer_with_profiling
+    alias_method :render_without_profiling, :render
+    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.

lib/liquid/tag.rb

@@ -5,8 +5,8 @@ module Liquid
     include ParserSwitching
 
     class << self
-      def parse(tag_name, markup, tokenizer, parse_context)
-        tag = new(tag_name, markup, parse_context)
+      def parse(tag_name, markup, tokenizer, options)
+        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)
-      previous_output_size = output.bytesize
-      super
+    def render(context)
+      output = super
       context.scopes.last[@to] = output
-      context.resource_limits.assign_score += (output.bytesize - previous_output_size)
-      output
+      context.resource_limits.assign_score += output.bytesize
+      ''.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)
-      output
+    def render(_context)
+      ''.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
-
-        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
-
+        result = context.evaluate(@variables[iteration])
         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
-      output
+      value.to_s
     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)
-      if @else_block
-        @else_block.render_to_output_buffer(context, output)
-      else
-        output
-      end
+    def render_else(context)
+      @else_block ? @else_block.render(context) : ''.freeze
     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 = ''
-        super(context, block_output)
+        output = super
 
-        if block_output != context.registers[:ifchanged]
-          context.registers[:ifchanged] = block_output
-          output << block_output
+        if output != context.registers[:ifchanged]
+          context.registers[:ifchanged] = 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(
-        template_name,
-        context: context,
-        parse_context: parse_context
-      )
-
+      partial = load_cached_partial(template_name, 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
-
-      output << value.to_s
-      output
+      value.to_s
     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)
-      output << @body
-      output
+    def render(_context)
+      @body
     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}\">"
-          super
-          output << '</td>'
+          result << "<td class=\"col#{tablerowloop.col}\">" << super << '</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
-
-      output << "</tr>\n"
-      output
+      result << "</tr>\n"
+      result
     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
-          @root.render_to_output_buffer(context, output || '')
+        result = with_profiling(context) do
+          @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)
-      @for_liquid_tag = for_liquid_tag
+      @line_number = line_numbers ? 1 : nil
       @tokens = tokenize
     end
 
     def shift
-      token = @tokens.shift or return
-
-      if @line_number
-        @line_number += @for_liquid_tag ? 1 : token.count("\n")
-      end
-
+      token = @tokens.shift
+      @line_number += token.count("\n") if @line_number && token
       token
     end
 
     private
 
     def tokenize
+      @source = @source.source if @source.respond_to?(:source)
       return [] if @source.to_s.empty?
 
-      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/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
-  LOG_LABEL   = "Profiling: ".rjust(14).freeze
-  REPORTS_DIR = File.expand_path('.memprof', __dir__).freeze
+def profile(phase, &block)
+  puts
+  puts "#{phase}:"
+  puts
 
-  def self.run
-    puts
-    yield new
-  end
+  report = MemoryProfiler.report(&block)
 
-  def initialize
-    @allocated = []
-    @retained  = []
-    @headings  = []
-  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
+  report.pretty_print(
+    color_output: true,
+    scale_bytes: true,
+    detailed_report: true
+  )
 end
 
 Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
 
-runner = ThemeRunner.new
-Profiler.run do |x|
-  x.profile('parse') { runner.compile }
-  x.profile('render') { runner.render }
-  x.tabulate
-end
+profiler = ThemeRunner.new
+
+profile("Parsing") { profiler.compile }
+profile("Rendering") { profiler.render }

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']
       }
-
-      output << wrap_in_form(article, render_all(@nodelist, context, output))
-      output
+      wrap_in_form(article, render_all(@nodelist, context))
     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)
-    output << ' '
-    output
+  def render(*args)
+    " "
   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 %}"))
-    end
+    assert_template_result(" " * N, wrap_in_for("{% foobar %}"))
   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)
-    output << @template_name[1..-2]
-    output
+  def render(context)
+    @template_name[1..-2]
   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
-      assert Liquid::Template.parse("{% testtag %} {% endtesttag %}")
-    end
-  end
-
-  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
+    Liquid::Template.register_tag("testtag", Block)
+    assert Liquid::Template.parse("{% testtag %} {% endtesttag %}")
+  ensure
+    Liquid::Template.tags.delete('testtag')
   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 (1..5), @context['(1..test)']
-    assert_equal (5..5), @context['(test..test)']
+    assert_equal ReversableRange.new(1, 5), @context['(1..5)']
+    assert_equal ReversableRange.new(1, 5), @context['(1..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