remove unnecessary tags

Add artificial execution time in profiler tests

.github/probots.yml

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

.github/workflows/liquid.yml

@@ -0,0 +1,39 @@
+name: Liquid
+on: [push, pull_request]
+jobs:
+  test:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        entry:
+          - { ruby: 2.5, allowed-failure: false } # minimum supported
+          - { ruby: 3.1, allowed-failure: false } # latest
+          - { ruby: ruby-head, allowed-failure: true }
+    name: test (${{ matrix.entry.ruby }})
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.entry.ruby }}
+      - uses: actions/cache@v1
+        with:
+          path: vendor/bundle
+          key: ${{ runner.os }}-gems-${{ hashFiles('Gemfile') }}
+          restore-keys: ${{ runner.os }}-gems-
+      - run: bundle install --jobs=3 --retry=3 --path=vendor/bundle
+      - run: bundle exec rake
+        continue-on-error: ${{ matrix.entry.allowed-failure }}
+  memory_profile:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.7
+      - uses: actions/cache@v1
+        with:
+          path: vendor/bundle
+          key: ${{ runner.os }}-gems-${{ hashFiles('Gemfile') }}
+          restore-keys: ${{ runner.os }}-gems-
+      - run: bundle install --jobs=3 --retry=3 --path=vendor/bundle
+      - run: bundle exec rake memory_profile:run

.gitignore

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

.rubocop.yml

@@ -1,125 +1,24 @@
-inherit_from: ./.rubocop_todo.yml
+inherit_gem:
+  rubocop-shopify: rubocop.yml
+
+inherit_from:
+  - .rubocop_todo.yml
+
+require: rubocop-performance
+
+Performance:
+  Enabled: true
 
 AllCops:
+  TargetRubyVersion: 2.5
+  NewCops: disable
   Exclude:
-    - 'performance/shopify/*'
-    - 'pkg/**'
+    - 'vendor/bundle/**/*'
 
-Metrics/BlockNesting:
-  Max: 3
+Naming/MethodName:
   Exclude:
-    - 'lib/liquid/block_body.rb'
+    - 'example/server/liquid_servlet.rb'
 
-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
-
-Lint/EndAlignment:
-  AlignWith: 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
-
-Style/SpaceInsideBrackets:
-  Enabled: false
-
-Style/SpaceBeforeBlockBraces:
-  Enabled: false
-
-Style/Documentation:
-  Enabled: false
-
-Style/ClassAndModuleChildren:
-  Enabled: false
-
-Style/TrailingComma:
-  Enabled: false
-
-Style/IndentHash:
-  EnforcedStyle: consistent
-
-Style/FormatString:
-  Enabled: false
-
-Style/AlignParameters:
-  EnforcedStyle: with_fixed_indentation
-
-Style/MultilineOperationIndentation:
-  EnforcedStyle: indented
-
-Style/IfUnlessModifier:
-  Enabled: false
-
-Style/RaiseArgs:
-  Enabled: false
-
-Style/DeprecatedHashMethods:
-  Enabled: false
-
-Style/RegexpLiteral:
-  Enabled: false
-
-Style/SymbolLiteral:
-  Enabled: false
-
-Performance/Count:
-  Enabled: false
-
-Style/ConstantName:
-  Enabled: false
-
-Style/CaseIndentation:
-  Enabled: false
-
-Style/ClassVars:
-  Enabled: false
-
-Style/PerlBackrefs:
-  Enabled: false
-
-Style/TrivialAccessors:
-  AllowPredicates: true
-
-Style/WordArray:
-  Enabled: false
+# Backport https://github.com/Shopify/ruby-style-guide/pull/258
+Layout/BeginEndAlignment:
+  Enabled: true

.rubocop_todo.yml

@@ -1,72 +1,57 @@
-# This configuration was generated by `rubocop --auto-gen-config`
-# on 2015-06-08 18:16:16 +0000 using RuboCop version 0.32.0.
+# This configuration was generated by
+# `rubocop --auto-gen-config`
+# on 2020-12-11 18:53:41 UTC using RuboCop version 1.6.1.
 # The point is for the user to remove these configuration records
 # one by one as the offenses are removed from the code base.
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 5
-Lint/NestedMethodDefinition:
-  Enabled: false
-
-# Offense count: 53
-Metrics/AbcSize:
-  Max: 58
-
-# Offense count: 12
-Metrics/CyclomaticComplexity:
-  Max: 15
-
-# Offense count: 553
-# Configuration parameters: AllowURI, URISchemes.
-Metrics/LineLength:
-  Max: 294
-
-# Offense count: 77
-# Configuration parameters: CountComments.
-Metrics/MethodLength:
-  Max: 46
-
-# Offense count: 6
-Metrics/PerceivedComplexity:
-  Max: 13
-
-# Offense count: 1
-Style/AccessorMethodName:
-  Enabled: false
-
-# Offense count: 1
+# Offense count: 2
 # Cop supports --auto-correct.
-Style/ClosingParenthesisIndentation:
-  Enabled: false
+# Configuration parameters: EnforcedStyle.
+# SupportedStyles: runtime_error, standard_error
+Lint/InheritException:
+  Exclude:
+    - 'lib/liquid/interrupts.rb'
 
-# Offense count: 3
-# Configuration parameters: MinBodyLength.
-Style/GuardClause:
-  Enabled: false
+# Offense count: 113
+# Cop supports --auto-correct.
+# Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
+# URISchemes: http, https
+Layout/LineLength:
+  Max: 260
 
-# Offense count: 4
-# Configuration parameters: EnforcedStyle, SupportedStyles.
-Style/MethodName:
-  Enabled: false
+# Offense count: 8
+Lint/MissingSuper:
+  Exclude:
+    - 'lib/liquid/forloop_drop.rb'
+    - 'lib/liquid/tablerowloop_drop.rb'
+    - 'test/integration/assign_test.rb'
+    - 'test/integration/context_test.rb'
+    - 'test/integration/filter_test.rb'
+    - 'test/integration/standard_filter_test.rb'
+    - 'test/integration/tags/for_tag_test.rb'
+    - 'test/integration/tags/table_row_test.rb'
 
-# Offense count: 1
-Style/MultilineBlockChain:
-  Enabled: false
+# Offense count: 43
+Naming/ConstantName:
+  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'
+    - 'lib/liquid/tags/if.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: EnforcedStyle, MinBodyLength, SupportedStyles.
-Style/Next:
-  Enabled: false
-
-# Offense count: 7
-# Cop supports --auto-correct.
-# Configuration parameters: AllowAsExpressionSeparator.
-Style/Semicolon:
-  Enabled: false
-
-# Offense count: 1
-# Cop supports --auto-correct.
-# Configuration parameters: MaxLineLength.
-Style/WhileUntilModifier:
-  Enabled: false
+Style/ClassVars:
+  Exclude:
+    - 'lib/liquid/condition.rb'

.travis.yml

@@ -1,29 +0,0 @@
-language: ruby
-
-rvm:
-  - 2.1
-  - 2.2
-  - 2.3.3
-  - ruby-head
-  - jruby-head
-#  - rbx-2
-
-sudo: false
-
-addons:
-  apt:
-    packages:
-    - libgmp3-dev
-
-matrix:
-  allow_failures:
-    - rvm: jruby-head
-
-install:
-  - gem install rainbow -v 2.2.1
-  - bundle install
-
-script: "bundle exec rake"
-
-notifications:
-  disable: true

CONTRIBUTING.md

@@ -5,6 +5,7 @@
 * Bugfixes
 * Performance improvements
 * Features that are likely to be useful to the majority of Liquid users
+* Documentation updates that are concise and likely to be useful to the majority of Liquid users
 
 ## Things we won't merge
 
@@ -14,12 +15,14 @@
 * Features that can easily be implemented on top of Liquid (for example as a custom filter or custom filesystem)
 * Code that does not include tests
 * Code that breaks existing tests
+* Documentation changes that are verbose, incorrect or not important to most people (we want to keep it simple and easy to understand)
 
 ## Workflow
 
+* [Sign the CLA](https://cla.shopify.com/) if you haven't already
 * Fork the Liquid repository
 * Create a new branch in your fork
+  * For updating [Liquid documentation](https://shopify.github.io/liquid/), create it from `gh-pages` branch. (You can skip tests.)
 * If it makes sense, add tests for your code and/or run a performance benchmark
 * Make sure all tests pass (`bundle exec rake`)
 * Create a pull request
-

Gemfile

@@ -1,17 +1,28 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
+git_source(:github) do |repo_name|
+  "https://github.com/#{repo_name}.git"
+end
 
 gemspec
-gem 'stackprof', platforms: :mri_21
 
 group :benchmark, :test do
   gem 'benchmark-ips'
+  gem 'memory_profiler'
+  gem 'terminal-table'
+
+  install_if -> { RUBY_PLATFORM !~ /mingw|mswin|java/ && RUBY_ENGINE != 'truffleruby' } do
+    gem 'stackprof'
+  end
 end
 
 group :test do
-  gem 'spy', '0.4.1'
-  gem 'rubocop', '0.34.2'
+  gem 'rubocop', '~> 1.4', require: false
+  gem 'rubocop-shopify', '~> 1.0.7', require: false
+  gem 'rubocop-performance', require: false
 
-  platform :mri do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'bd53db95de3d44d631e7c5a267c3d934e66107dd'
+  platform :mri, :truffleruby do
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'master'
   end
 end

History.md

@@ -1,5 +1,130 @@
 # Liquid Change Log
 
+## 5.3.0 (unreleased)
+
+### Fixes
+* StandardFilter: Fix missing @context on iterations (#1525) [Thierry Joyal]
+
+### Deprecation
+* Condition#evaluate to require mandatory context argument in Liquid 6.0.0 (#1527) [Thierry Joyal]
+
+## 5.2.0 2022-03-01
+
+### Features
+* Add `remove_last`, and `replace_last` filters (#1422) [Anders Hagbard]
+* Eagerly cache global filters (#1524) [Jean Boussier]
+
+### Fixes
+* Fix some internal errors in filters from invalid input (#1476) [Dylan Thacker-Smith]
+* Allow dash in filter kwarg name for consistency with Liquid::C (#1518) [CP Clermont]
+
+## 5.1.0 / 2021-09-09
+
+### Features
+* Add `base64_encode`, `base64_decode`, `base64_url_safe_encode`, and `base64_url_safe_decode` filters (#1450) [Daniel Insley]
+* Introduce `to_liquid_value` in `Liquid::Drop` (#1441) [Michael Go]
+
+### Fixes
+* Fix support for using a String subclass for the liquid source (#1421) [Dylan Thacker-Smith]
+* Add `ParseTreeVisitor` to `RangeLookup` (#1470) [CP Clermont]
+* Translate `RangeError` to `Liquid::Error` for `truncatewords` with large int (#1431) [Dylan Thacker-Smith]
+
+## 5.0.1 / 2021-03-24
+
+### Fixes
+* Add ParseTreeVisitor to Echo tag (#1414) [CP Clermont]
+* Test with ruby 3.0 as the latest ruby version (#1398) [Dylan Thacker-Smith]
+* Handle carriage return in newlines_to_br (#1391) [Unending]
+
+### Performance Improvements
+* Use split limit in truncatewords (#1361) [Dylan Thacker-Smith]
+
+## 5.0.0 / 2021-01-06
+
+### Features
+* Add new `{% render %}` tag (#1122) [Samuel Doiron]
+* Add support for `as` in `{% render %}` and `{% include %}` (#1181) [Mike Angell]
+* Add `{% liquid %}` and `{% echo %}` tags (#1086) [Justin Li]
+* Add [usage tracking](README.md#usage-tracking) [Mike Angell]
+* Add `Tag.disable_tags` for disabling tags that prepend `Tag::Disableable` at render time (#1162, #1274, #1275) [Mike Angell]
+* Support using a profiler for multiple renders (#1365, #1366) [Dylan Thacker-Smith]
+
+### Fixes
+* Fix catastrophic backtracking in `RANGES_REGEX` regular expression (#1357) [Dylan Thacker-Smith]
+* Make sure the for tag's limit and offset are integers (#1094) [David Cornu]
+* Invokable methods for enumerable reject include (#1151) [Thierry Joyal]
+* Allow `default` filter to handle `false` as value (#1144) [Mike Angell]
+* Fix render length resource limit so it doesn't multiply nested output (#1285) [Dylan Thacker-Smith]
+* Fix duplication of text in raw tags (#1304) [Peter Zhu]
+* Fix strict parsing of find variable with a name expression (#1317) [Dylan Thacker-Smith]
+* Use monotonic time to measure durations in Liquid::Profiler (#1362) [Dylan Thacker-Smith]
+
+### Breaking Changes
+* Require Ruby >= 2.5 (#1131, #1310) [Mike Angell, Dylan Thacker-Smith]
+* Remove support for taint checking (#1268) [Dylan Thacker-Smith]
+* Split Strainer class into StrainerFactory and StrainerTemplate (#1208) [Thierry Joyal]
+* Remove handling of a nil context in the Strainer class (#1218) [Thierry Joyal]
+* Handle `BlockBody#blank?` at parse time (#1287) [Dylan Thacker-Smith]
+* Pass the tag markup and tokenizer to `Document#unknown_tag` (#1290) [Dylan Thacker-Smith]
+* And several internal changes
+
+### Performance Improvements
+* Reduce allocations (#1073, #1091, #1115, #1099, #1117, #1141, #1322, #1341) [Richard Monette, Florian Weingarten, Ashwin Maroli]
+* Improve resources limits performance (#1093, #1323) [Florian Weingarten, Dylan Thacker-Smith]
+
+## 4.0.3 / 2019-03-12
+
+### Fixed
+* Fix break and continue tags inside included templates in loops (#1072) [Justin Li]
+
+## 4.0.2 / 2019-03-08
+
+### Changed
+* Add `where` filter (#1026) [Samuel Doiron]
+* Add `ParseTreeVisitor` to iterate the Liquid AST (#1025) [Stephen Paul Weber]
+* Improve `strip_html` performance (#1032) [printercu]
+
+### Fixed
+* Add error checking for invalid combinations of inputs to sort, sort_natural, where, uniq, map, compact filters (#1059) [Garland Zhang]
+* Validate the character encoding in url_decode (#1070) [Clayton Smith]
+
+## 4.0.1 / 2018-10-09
+
+### Changed
+* Add benchmark group in Gemfile (#855) [Jerry Liu]
+* Allow benchmarks to benchmark render by itself (#851) [Jerry Liu]
+* Avoid calling `line_number` on String node when rescuing a render error. (#860) [Dylan Thacker-Smith]
+* Avoid duck typing to detect whether to call render on a node. [Dylan Thacker-Smith]
+* Clarify spelling of `reversed` on `for` block tag (#843) [Mark Crossfield]
+* Replace recursion with loop to avoid potential stack overflow from malicious input (#891, #892) [Dylan Thacker-Smith]
+* Limit block tag nesting to 100 (#894) [Dylan Thacker-Smith]
+* Replace `assert_equal nil` with `assert_nil` (#895) [Dylan Thacker-Smith]
+* Remove Spy Gem (#896) [Dylan Thacker-Smith]
+* Add `collection_name` and `variable_name` reader to `For` block (#909)
+* Symbols render as strings (#920) [Justin Li]
+* Remove default value from Hash objects (#932) [Maxime Bedard]
+* Remove one level of nesting (#944) [Dylan Thacker-Smith]
+* Update Rubocop version (#952) [Justin Li]
+* Add `at_least` and `at_most` filters (#954, #958) [Nithin Bekal]
+* Add a regression test for a liquid-c trim mode bug (#972) [Dylan Thacker-Smith]
+* Use https rather than git protocol to fetch liquid-c [Dylan Thacker-Smith]
+* Add tests against Ruby 2.4 (#963) and 2.5 (#981)
+* Replace RegExp literals with constants (#988) [Ashwin Maroli]
+* Replace unnecessary `#each_with_index` with `#each` (#992) [Ashwin Maroli]
+* Improve the unexpected end delimiter message for block tags. (#1003) [Dylan Thacker-Smith]
+* Refactor and optimize rendering (#1005) [Christopher Aue]
+* Add installation instruction (#1006) [Ben Gift]
+* Remove Circle CI (#1010)
+* Rename deprecated `BigDecimal.new` to `BigDecimal` (#1024) [Koichi ITO]
+* Rename deprecated Rubocop name (#1027) [Justin Li]
+
+### Fixed
+* Handle `join` filter on non String joiners (#857) [Richard Monette]
+* Fix duplicate inclusion condition logic error of `Liquid::Strainer.add_filter` method (#861)
+* Fix `escape`, `url_encode`, `url_decode` not handling non-string values (#898) [Thierry Joyal]
+* Fix raise when variable is defined but nil when using `strict_variables` [Pascal Betz]
+* Fix `sort` and `sort_natural` to handle arrays with nils (#930) [Eric Chan]
+
 ## 4.0.0 / 2016-12-14 / branch "4-0-stable"
 
 ### Changed

README.md

@@ -5,7 +5,7 @@
 
 * [Contributing guidelines](CONTRIBUTING.md)
 * [Version history](History.md)
-* [Liquid documentation from Shopify](http://docs.shopify.com/themes/liquid-basics)
+* [Liquid documentation from Shopify](https://shopify.dev/api/liquid)
 * [Liquid Wiki at GitHub](https://github.com/Shopify/liquid/wiki)
 * [Website](http://liquidmarkup.org/)
 
@@ -42,6 +42,8 @@ Liquid is a template engine which was written with very specific requirements:
 
 ## How to use Liquid
 
+Install Liquid by adding `gem 'liquid'` to your gemfile.
+
 Liquid supports a very simple API based around the Liquid::Template class.
 For standard use you can just pass it the content of a file and call render with a parameters hash.
 
@@ -54,7 +56,7 @@ For standard use you can just pass it the content of a file and call render with
 
 Setting the error mode of Liquid lets you specify how strictly you want your templates to be interpreted.
 Normally the parser is very lax and will accept almost anything without error. Unfortunately this can make
-it very hard to debug and can lead to unexpected behaviour. 
+it very hard to debug and can lead to unexpected behaviour.
 
 Liquid also comes with a stricter parser that can be used when editing templates to give better error messages
 when templates are invalid. You can enable this new parser like this:
@@ -104,3 +106,9 @@ 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

@@ -1,29 +1,39 @@
+# frozen_string_literal: true
+
 require 'rake'
 require 'rake/testtask'
-$LOAD_PATH.unshift File.expand_path("../lib", __FILE__)
+$LOAD_PATH.unshift(File.expand_path("../lib", __FILE__))
 require "liquid/version"
 
-task default: [:rubocop, :test]
+task(default: [:test, :rubocop])
 
-desc 'run test suite with default parser'
+desc('run test suite with default parser')
 Rake::TestTask.new(:base_test) do |t|
-  t.libs << '.' << 'lib' << 'test'
+  t.libs << 'lib' << 'test'
   t.test_files = FileList['test/{integration,unit}/**/*_test.rb']
-  t.verbose = false
+  t.verbose    = false
 end
 
-desc 'run test suite with warn error mode'
+Rake::TestTask.new(:integration_test) do |t|
+  t.libs << 'lib' << 'test'
+  t.test_files = FileList['test/integration/**/*_test.rb']
+  t.verbose    = false
+end
+
+desc('run test suite with warn error mode')
 task :warn_test do
   ENV['LIQUID_PARSER_MODE'] = 'warn'
   Rake::Task['base_test'].invoke
 end
 
 task :rubocop do
-  require 'rubocop/rake_task'
-  RuboCop::RakeTask.new
+  if RUBY_ENGINE == 'ruby'
+    require 'rubocop/rake_task'
+    RuboCop::RakeTask.new
+  end
 end
 
-desc 'runs test suite with both strict and lax parsers'
+desc('runs test suite with both strict and lax parsers')
 task :test do
   ENV['LIQUID_PARSER_MODE'] = 'lax'
   Rake::Task['base_test'].invoke
@@ -32,20 +42,20 @@ task :test do
   Rake::Task['base_test'].reenable
   Rake::Task['base_test'].invoke
 
-  if RUBY_ENGINE == 'ruby'
-    ENV['LIQUID-C'] = '1'
+  if RUBY_ENGINE == 'ruby' || RUBY_ENGINE == 'truffleruby'
+    ENV['LIQUID_C'] = '1'
 
     ENV['LIQUID_PARSER_MODE'] = 'lax'
-    Rake::Task['base_test'].reenable
-    Rake::Task['base_test'].invoke
+    Rake::Task['integration_test'].reenable
+    Rake::Task['integration_test'].invoke
 
     ENV['LIQUID_PARSER_MODE'] = 'strict'
-    Rake::Task['base_test'].reenable
-    Rake::Task['base_test'].invoke
+    Rake::Task['integration_test'].reenable
+    Rake::Task['integration_test'].invoke
   end
 end
 
-task gem: :build
+task(gem: :build)
 task :build do
   system "gem build liquid.gemspec"
 end
@@ -85,7 +95,14 @@ namespace :profile do
   end
 end
 
-desc "Run example"
+namespace :memory_profile do
+  desc "Run memory profiler"
+  task :run do
+    ruby "./performance/memory_profile.rb"
+  end
+end
+
+desc("Run example")
 task :example do
   ruby "-w -d -Ilib example/server/server.rb"
 end

circle.yml

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

example/server/example_servlet.rb

@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 module ProductsFilter
   def price(integer)
-    sprintf("$%.2d USD", integer / 100.0)
+    format("$%.2d USD", integer / 100.0)
   end
 
   def prettyprint(text)

example/server/liquid_servlet.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class LiquidServlet < WEBrick::HTTPServlet::AbstractServlet
   def do_GET(req, res)
     handle(:get, req, res)
@@ -9,17 +11,17 @@ class LiquidServlet < WEBrick::HTTPServlet::AbstractServlet
 
   private
 
-  def handle(type, req, res)
-    @request = req
+  def handle(_type, req, res)
+    @request  = req
     @response = res
 
     @request.path_info =~ /(\w+)\z/
-    @action = $1 || 'index'
+    @action  = Regexp.last_match(1) || 'index'
     @assigns = send(@action) if respond_to?(@action)
 
     @response['Content-Type'] = "text/html"
     @response.status = 200
-    @response.body = Liquid::Template.parse(read_template).render(@assigns, filters: [ProductsFilter])
+    @response.body   = Liquid::Template.parse(read_template).render(@assigns, filters: [ProductsFilter])
   end
 
   def read_template(filename = @action)

example/server/server.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'webrick'
 require 'rexml/document'
 
@@ -8,5 +10,5 @@ require_relative 'example_servlet'
 # Setup webrick
 server = WEBrick::HTTPServer.new(Port: ARGV[1] || 3000)
 server.mount('/', Servlet)
-trap("INT"){ server.shutdown }
+trap("INT") { server.shutdown }
 server.start

lib/liquid.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # Copyright (c) 2005 Tobias Luetke
 #
 # Permission is hereby granted, free of charge, to any person obtaining
@@ -21,10 +23,10 @@
 
 module Liquid
   FilterSeparator             = /\|/
-  ArgumentSeparator           = ','.freeze
-  FilterArgumentSeparator     = ':'.freeze
-  VariableAttributeSeparator  = '.'.freeze
-  WhitespaceControl           = '-'.freeze
+  ArgumentSeparator           = ','
+  FilterArgumentSeparator     = ':'
+  VariableAttributeSeparator  = '.'
+  WhitespaceControl           = '-'
   TagStart                    = /\{\%/
   TagEnd                      = /\%\}/
   VariableSignature           = /\(?[\w\-\.\[\]]\)?/
@@ -34,17 +36,20 @@ module Liquid
   VariableIncompleteEnd       = /\}\}?/
   QuotedString                = /"[^"]*"|'[^']*'/
   QuotedFragment              = /#{QuotedString}|(?:[^\s,\|'"]|#{QuotedString})+/o
-  TagAttributes               = /(\w+)\s*\:\s*(#{QuotedFragment})/o
+  TagAttributes               = /(\w[\w-]*)\s*\:\s*(#{QuotedFragment})/o
   AnyStartingTag              = /#{TagStart}|#{VariableStart}/o
   PartialTemplateParser       = /#{TagStart}.*?#{TagEnd}|#{VariableStart}.*?#{VariableIncompleteEnd}/om
   TemplateParser              = /(#{PartialTemplateParser}|#{AnyStartingTag})/om
   VariableParser              = /\[[^\]]+\]|#{VariableSegment}+\??/o
 
+  RAISE_EXCEPTION_LAMBDA = ->(_e) { raise }
+
   singleton_class.send(:attr_accessor, :cache_classes)
   self.cache_classes = true
 end
 
 require "liquid/version"
+require 'liquid/parse_tree_visitor'
 require 'liquid/lexer'
 require 'liquid/parser'
 require 'liquid/i18n'
@@ -54,11 +59,14 @@ require 'liquid/forloop_drop'
 require 'liquid/extensions'
 require 'liquid/errors'
 require 'liquid/interrupts'
-require 'liquid/strainer'
+require 'liquid/strainer_template'
+require 'liquid/strainer_factory'
 require 'liquid/expression'
 require 'liquid/context'
 require 'liquid/parser_switching'
 require 'liquid/tag'
+require 'liquid/tag/disabler'
+require 'liquid/tag/disableable'
 require 'liquid/block'
 require 'liquid/block_body'
 require 'liquid/document'
@@ -73,6 +81,11 @@ require 'liquid/condition'
 require 'liquid/utils'
 require 'liquid/tokenizer'
 require 'liquid/parse_context'
+require 'liquid/partial_cache'
+require 'liquid/usage'
+require 'liquid/register'
+require 'liquid/static_registers'
+require 'liquid/template_factory'
 
 # Load all the tags of the standard library
 #

lib/liquid/block.rb

@@ -1,16 +1,22 @@
+# frozen_string_literal: true
+
 module Liquid
   class Block < Tag
+    MAX_DEPTH = 100
+
     def initialize(tag_name, markup, options)
       super
       @blank = true
     end
 
     def parse(tokens)
-      @body = BlockBody.new
+      @body = new_body
       while parse_body(@body, tokens)
       end
+      @body.freeze
     end
 
+    # For backwards compatibility
     def render(context)
       @body.render(context)
     end
@@ -23,20 +29,29 @@ module Liquid
       @body.nodelist
     end
 
-    def unknown_tag(tag, _params, _tokens)
-      case tag
-      when 'else'.freeze
-        raise SyntaxError.new(parse_context.locale.t("errors.syntax.unexpected_else".freeze,
-          block_name: block_name))
-      when 'end'.freeze
-        raise SyntaxError.new(parse_context.locale.t("errors.syntax.invalid_delimiter".freeze,
+    def unknown_tag(tag_name, _markup, _tokenizer)
+      Block.raise_unknown_tag(tag_name, block_name, block_delimiter, parse_context)
+    end
+
+    # @api private
+    def self.raise_unknown_tag(tag, block_name, block_delimiter, parse_context)
+      if tag == 'else'
+        raise SyntaxError, parse_context.locale.t("errors.syntax.unexpected_else",
+          block_name: block_name)
+      elsif tag.start_with?('end')
+        raise SyntaxError, parse_context.locale.t("errors.syntax.invalid_delimiter",
+          tag: tag,
           block_name: block_name,
-          block_delimiter: block_delimiter))
+          block_delimiter: block_delimiter)
       else
-        raise SyntaxError.new(parse_context.locale.t("errors.syntax.unknown_tag".freeze, tag: tag))
+        raise SyntaxError, parse_context.locale.t("errors.syntax.unknown_tag", tag: tag)
       end
     end
 
+    def raise_tag_never_closed(block_name)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_never_closed", block_name: block_name)
+    end
+
     def block_name
       @tag_name
     end
@@ -45,20 +60,32 @@ module Liquid
       @block_delimiter ||= "end#{block_name}"
     end
 
-    protected
+    private
 
+    # @api public
+    def new_body
+      parse_context.new_block_body
+    end
+
+    # @api public
     def parse_body(body, tokens)
-      body.parse(tokens, parse_context) do |end_tag_name, end_tag_params|
-        @blank &&= body.blank?
+      if parse_context.depth >= MAX_DEPTH
+        raise StackLevelError, "Nesting too deep"
+      end
+      parse_context.depth += 1
+      begin
+        body.parse(tokens, parse_context) do |end_tag_name, end_tag_params|
+          @blank &&= body.blank?
 
-        return false if end_tag_name == block_delimiter
-        unless end_tag_name
-          raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name))
+          return false if end_tag_name == block_delimiter
+          raise_tag_never_closed(block_name) unless end_tag_name
+
+          # this tag is not registered with the system
+          # pass it to the current block for special handling or error reporting
+          unknown_tag(end_tag_name, end_tag_params, tokens)
         end
-
-        # this tag is not registered with the system
-        # pass it to the current block for special handling or error reporting
-        unknown_tag(end_tag_name, end_tag_params, tokens)
+      ensure
+        parse_context.depth -= 1
       end
 
       true

lib/liquid/block_body.rb

@@ -1,52 +1,168 @@
+# frozen_string_literal: true
+
+require 'English'
+
 module Liquid
   class BlockBody
-    FullToken = /\A#{TagStart}#{WhitespaceControl}?\s*(\w+)\s*(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
-    ContentOfVariable = /\A#{VariableStart}#{WhitespaceControl}?(.*?)#{WhitespaceControl}?#{VariableEnd}\z/om
-    TAGSTART = "{%".freeze
-    VARSTART = "{{".freeze
+    LiquidTagToken      = /\A\s*(\w+)\s*(.*?)\z/o
+    FullToken           = /\A#{TagStart}#{WhitespaceControl}?(\s*)(\w+)(\s*)(.*?)#{WhitespaceControl}?#{TagEnd}\z/om
+    ContentOfVariable   = /\A#{VariableStart}#{WhitespaceControl}?(.*?)#{WhitespaceControl}?#{VariableEnd}\z/om
+    WhitespaceOrNothing = /\A\s*\z/
+    TAGSTART            = "{%"
+    VARSTART            = "{{"
 
     attr_reader :nodelist
 
     def initialize
       @nodelist = []
-      @blank = true
+      @blank    = true
     end
 
-    def parse(tokenizer, parse_context)
+    def parse(tokenizer, parse_context, &block)
+      raise FrozenError, "can't modify frozen Liquid::BlockBody" if frozen?
+
       parse_context.line_number = tokenizer.line_number
-      while token = tokenizer.shift
-        unless token.empty?
-          case
-          when token.start_with?(TAGSTART)
-            whitespace_handler(token, parse_context)
-            if token =~ FullToken
-              tag_name = $1
-              markup = $2
-              # fetch the tag from registered blocks
-              if tag = registered_tags[tag_name]
-                new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
-                @blank &&= new_tag.blank?
-                @nodelist << new_tag
-              else
-                # end parsing if we reach an unknown tag and let the caller decide
-                # determine how to proceed
-                return yield tag_name, markup
-              end
-            else
-              raise_missing_tag_terminator(token, parse_context)
-            end
-          when token.start_with?(VARSTART)
-            whitespace_handler(token, parse_context)
-            @nodelist << create_variable(token, parse_context)
-            @blank = false
-          else
-            if parse_context.trim_whitespace
-              token.lstrip!
-            end
-            parse_context.trim_whitespace = false
-            @nodelist << token
-            @blank &&= !!(token =~ /\A\s*\z/)
+
+      if tokenizer.for_liquid_tag
+        parse_for_liquid_tag(tokenizer, parse_context, &block)
+      else
+        parse_for_document(tokenizer, parse_context, &block)
+      end
+    end
+
+    def freeze
+      @nodelist.freeze
+      super
+    end
+
+    # @public_docs
+    # @type tag
+    # @category theme
+    # @title liquid
+    # @summary
+    #   Allows you to write multiple tags within one set of delimiters.
+    # @description
+    #   Use the [`echo`](/api/liquid/tags/theme-tags#echo) tag to output an expression within a `liquid` tag.
+    # @syntax
+    #   {% liquid
+    #     statement
+    #   %}
+    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 = Regexp.last_match(1)
+          markup   = Regexp.last_match(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
+
+    # @api private
+    def self.unknown_tag_in_liquid_tag(tag, parse_context)
+      Block.raise_unknown_tag(tag, 'liquid', '%}', parse_context)
+    end
+
+    # @api private
+    def self.raise_missing_tag_terminator(token, parse_context)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_termination", token: token, tag_end: TagEnd.inspect)
+    end
+
+    # @api private
+    def self.raise_missing_variable_terminator(token, parse_context)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.variable_termination", token: token, tag_end: VariableEnd.inspect)
+    end
+
+    # @api private
+    def self.render_node(context, output, node)
+      node.render_to_output_buffer(context, output)
+    rescue => exc
+      blank_tag = !node.instance_of?(Variable) && node.blank?
+      rescue_render_node(context, output, node.line_number, exc, blank_tag)
+    end
+
+    # @api private
+    def self.rescue_render_node(context, output, line_number, exc, blank_tag)
+      case exc
+      when MemoryError
+        raise
+      when UndefinedVariable, UndefinedDropMethod, UndefinedFilter
+        context.handle_error(exc, line_number)
+      else
+        error_message = context.handle_error(exc, line_number)
+        unless blank_tag # conditional for backwards compatibility
+          output << error_message
+        end
+      end
+    end
+
+    private def parse_liquid_tag(markup, parse_context)
+      liquid_tag_tokenizer = parse_context.new_tokenizer(
+        markup, start_line_number: parse_context.line_number, for_liquid_tag: true
+      )
+      parse_for_liquid_tag(liquid_tag_tokenizer, parse_context) do |end_tag_name, _end_tag_markup|
+        if end_tag_name
+          BlockBody.unknown_tag_in_liquid_tag(end_tag_name, parse_context)
+        end
+      end
+    end
+
+    private def parse_for_document(tokenizer, parse_context)
+      while (token = tokenizer.shift)
+        next if token.empty?
+        case
+        when token.start_with?(TAGSTART)
+          whitespace_handler(token, parse_context)
+          unless token =~ FullToken
+            BlockBody.raise_missing_tag_terminator(token, parse_context)
+          end
+          tag_name = Regexp.last_match(2)
+          markup   = Regexp.last_match(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 += Regexp.last_match(1).count("\n") + Regexp.last_match(3).count("\n")
+          end
+
+          if tag_name == 'liquid'
+            parse_liquid_tag(markup, parse_context)
+            next
+          end
+
+          unless (tag = registered_tags[tag_name])
+            # end parsing if we reach an unknown tag and let the caller decide
+            # determine how to proceed
+            return yield tag_name, markup
+          end
+          new_tag = tag.parse(tag_name, markup, tokenizer, parse_context)
+          @blank &&= new_tag.blank?
+          @nodelist << new_tag
+        when token.start_with?(VARSTART)
+          whitespace_handler(token, parse_context)
+          @nodelist << create_variable(token, parse_context)
+          @blank = false
+        else
+          if parse_context.trim_whitespace
+            token.lstrip!
+          end
+          parse_context.trim_whitespace = false
+          @nodelist << token
+          @blank &&= !!(token =~ WhitespaceOrNothing)
         end
         parse_context.line_number = tokenizer.line_number
       end
@@ -57,8 +173,12 @@ module Liquid
     def whitespace_handler(token, parse_context)
       if token[2] == WhitespaceControl
         previous_token = @nodelist.last
-        if previous_token.is_a? String
+        if previous_token.is_a?(String)
+          first_byte = previous_token.getbyte(0)
           previous_token.rstrip!
+          if previous_token.empty? && parse_context[:bug_compatible_whitespace_trimming] && first_byte
+            previous_token << first_byte
+          end
         end
       end
       parse_context.trim_whitespace = (token[-3] == WhitespaceControl)
@@ -68,69 +188,76 @@ module Liquid
       @blank
     end
 
+    # Remove blank strings in the block body for a control flow tag (e.g. `if`, `for`, `case`, `unless`)
+    # with a blank body.
+    #
+    # For example, in a conditional assignment like the following
+    #
+    # ```
+    # {% if size > max_size %}
+    #   {% assign size = max_size %}
+    # {% endif %}
+    # ```
+    #
+    # we assume the intention wasn't to output the blank spaces in the `if` tag's block body, so this method
+    # will remove them to reduce the render output size.
+    #
+    # Note that it is now preferred to use the `liquid` tag for this use case.
+    def remove_blank_strings
+      raise "remove_blank_strings only support being called on a blank block body" unless @blank
+      @nodelist.reject! { |node| node.instance_of?(String) }
+    end
+
     def render(context)
-      output = []
-      context.resource_limits.render_score += @nodelist.length
+      render_to_output_buffer(context, +'')
+    end
 
-      @nodelist.each do |token|
-        # Break out if we have any unhanded interrupts.
-        break if context.interrupt?
+    def render_to_output_buffer(context, output)
+      freeze unless frozen?
 
-        begin
+      context.resource_limits.increment_render_score(@nodelist.length)
+
+      idx = 0
+      while (node = @nodelist[idx])
+        if node.instance_of?(String)
+          output << node
+        else
+          render_node(context, output, node)
           # If we get an Interrupt that means the block must stop processing. An
           # Interrupt is any command that stops block execution such as {% break %}
-          # or {% continue %}
-          if token.is_a?(Continue) || token.is_a?(Break)
-            context.push_interrupt(token.interrupt)
-            break
-          end
-
-          node_output = render_node(token, context)
-
-          unless token.is_a?(Block) && token.blank?
-            output << node_output
-          end
-        rescue MemoryError => e
-          raise e
-        rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
-          context.handle_error(e, token.line_number)
-          output << nil
-        rescue ::StandardError => e
-          line_number = token.is_a?(String) ? nil : token.line_number
-          output << context.handle_error(e, line_number)
+          # or {% continue %}. These tags may also occur through Block or Include tags.
+          break if context.interrupt? # might have happened in a for-block
         end
+        idx += 1
+
+        context.resource_limits.increment_write_score(output)
       end
 
-      output.join
+      output
     end
 
     private
 
-    def render_node(node, context)
-      node_output = node.is_a?(String) ? node : node.render(context)
-      node_output = node_output.is_a?(Array) ? node_output.join : node_output.to_s
-
-      context.resource_limits.render_length += node_output.length
-      if context.resource_limits.reached?
-        raise MemoryError.new("Memory limits exceeded".freeze)
-      end
-      node_output
+    def render_node(context, output, node)
+      BlockBody.render_node(context, output, node)
     end
 
     def create_variable(token, parse_context)
-      token.scan(ContentOfVariable) do |content|
-        markup = content.first
+      if token =~ ContentOfVariable
+        markup = Regexp.last_match(1)
         return Variable.new(markup, parse_context)
       end
-      raise_missing_variable_terminator(token, parse_context)
+      BlockBody.raise_missing_variable_terminator(token, parse_context)
     end
 
+    # @deprecated Use {.raise_missing_tag_terminator} instead
     def raise_missing_tag_terminator(token, parse_context)
-      raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_termination".freeze, token: token, tag_end: TagEnd.inspect))
+      BlockBody.raise_missing_tag_terminator(token, parse_context)
     end
 
+    # @deprecated Use {.raise_missing_variable_terminator} instead
     def raise_missing_variable_terminator(token, parse_context)
-      raise SyntaxError.new(parse_context.locale.t("errors.syntax.variable_termination".freeze, token: token, tag_end: VariableEnd.inspect))
+      BlockBody.raise_missing_variable_terminator(token, parse_context)
     end
 
     def registered_tags

lib/liquid/condition.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Container for liquid nodes which conveniently wraps decision making logic
   #
@@ -6,60 +8,85 @@ module Liquid
   #   c = Condition.new(1, '==', 1)
   #   c.evaluate #=> true
   #
-  class Condition #:nodoc:
+  class Condition # :nodoc:
     @@operators = {
-      '=='.freeze => ->(cond, left, right) {  cond.send(:equal_variables, left, right) },
-      '!='.freeze => ->(cond, left, right) { !cond.send(:equal_variables, left, right) },
-      '<>'.freeze => ->(cond, left, right) { !cond.send(:equal_variables, left, right) },
-      '<'.freeze  => :<,
-      '>'.freeze  => :>,
-      '>='.freeze => :>=,
-      '<='.freeze => :<=,
-      'contains'.freeze => lambda do |cond, left, right|
+      '==' => ->(cond, left, right) {  cond.send(:equal_variables, left, right) },
+      '!=' => ->(cond, left, right) { !cond.send(:equal_variables, left, right) },
+      '<>' => ->(cond, left, right) { !cond.send(:equal_variables, left, right) },
+      '<' => :<,
+      '>' => :>,
+      '>=' => :>=,
+      '<=' => :<=,
+      'contains' => lambda do |_cond, left, right|
         if left && right && left.respond_to?(:include?)
           right = right.to_s if left.is_a?(String)
           left.include?(right)
         else
           false
         end
+      end,
+    }
+
+    class MethodLiteral
+      attr_reader :method_name, :to_s
+
+      def initialize(method_name, to_s)
+        @method_name = method_name
+        @to_s = to_s
       end
+    end
+
+    @@method_literals = {
+      'blank' => MethodLiteral.new(:blank?, '').freeze,
+      'empty' => MethodLiteral.new(:empty?, '').freeze,
     }
 
     def self.operators
       @@operators
     end
 
-    attr_reader :attachment
+    def self.parse_expression(parse_context, markup)
+      @@method_literals[markup] || parse_context.parse_expression(markup)
+    end
+
+    attr_reader :attachment, :child_condition
     attr_accessor :left, :operator, :right
 
     def initialize(left = nil, operator = nil, right = nil)
-      @left = left
+      @left     = left
       @operator = operator
-      @right = right
+      @right    = right
+
       @child_relation  = nil
       @child_condition = nil
     end
 
-    def evaluate(context = Context.new)
-      result = interpret_condition(left, right, operator, context)
+    def evaluate(context = deprecated_default_context)
+      condition = self
+      result = nil
+      loop do
+        result = interpret_condition(condition.left, condition.right, condition.operator, context)
 
-      case @child_relation
-      when :or
-        result || @child_condition.evaluate(context)
-      when :and
-        result && @child_condition.evaluate(context)
-      else
-        result
+        case condition.child_relation
+        when :or
+          break if result
+        when :and
+          break unless result
+        else
+          break
+        end
+        condition = condition.child_condition
       end
+      result
     end
 
     def or(condition)
-      @child_relation = :or
+      @child_relation  = :or
       @child_condition = condition
     end
 
     def and(condition)
-      @child_relation = :and
+      @child_relation  = :and
       @child_condition = condition
     end
 
@@ -72,13 +99,17 @@ module Liquid
     end
 
     def inspect
-      "#<Condition #{[@left, @operator, @right].compact.join(' '.freeze)}>"
+      "#<Condition #{[@left, @operator, @right].compact.join(' ')}>"
     end
 
+    protected
+
+    attr_reader :child_relation
+
     private
 
     def equal_variables(left, right)
-      if left.is_a?(Liquid::Expression::MethodLiteral)
+      if left.is_a?(MethodLiteral)
         if right.respond_to?(left.method_name)
           return right.send(left.method_name)
         else
@@ -86,7 +117,7 @@ module Liquid
         end
       end
 
-      if right.is_a?(Liquid::Expression::MethodLiteral)
+      if right.is_a?(MethodLiteral)
         if left.respond_to?(right.method_name)
           return left.send(right.method_name)
         else
@@ -103,10 +134,10 @@ module Liquid
       # return this as the result.
       return context.evaluate(left) if op.nil?
 
-      left = context.evaluate(left)
-      right = context.evaluate(right)
+      left  = Liquid::Utils.to_liquid_value(context.evaluate(left))
+      right = Liquid::Utils.to_liquid_value(context.evaluate(right))
 
-      operation = self.class.operators[op] || raise(Liquid::ArgumentError.new("Unknown operator #{op}"))
+      operation = self.class.operators[op] || raise(Liquid::ArgumentError, "Unknown operator #{op}")
 
       if operation.respond_to?(:call)
         operation.call(self, left, right)
@@ -114,10 +145,25 @@ module Liquid
         begin
           left.send(operation, right)
         rescue ::ArgumentError => e
-          raise Liquid::ArgumentError.new(e.message)
+          raise Liquid::ArgumentError, e.message
         end
       end
     end
+
+    def deprecated_default_context
+      warn("DEPRECATION WARNING: Condition#evaluate without a context argument is deprecated" \
+        " and will be removed from Liquid 6.0.0.")
+      Context.new
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.left, @node.right,
+          @node.child_condition, @node.attachment
+        ].compact
+      end
+    end
   end
 
   class ElseCondition < Condition

lib/liquid/context.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Context keeps the variable stack and resolves variables, as well as keywords
   #
@@ -12,37 +14,49 @@ module Liquid
   #
   #   context['bob']  #=> nil  class Context
   class Context
-    attr_reader :scopes, :errors, :registers, :environments, :resource_limits
+    attr_reader :scopes, :errors, :registers, :environments, :resource_limits, :static_registers, :static_environments
     attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
-    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
+    # rubocop:disable Metrics/ParameterLists
+    def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_environments: {}, &block)
+      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_environments, &block)
+    end
 
-      @this_stack_used = false
+    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_environments = {})
+      @environments = [environments]
+      @environments.flatten!
+
+      @static_environments = [static_environments].flat_map(&:freeze).freeze
+      @scopes              = [(outer_scope || {})]
+      @registers           = registers
+      @errors              = []
+      @partial             = false
+      @strict_variables    = false
+      @resource_limits     = resource_limits || ResourceLimits.new(Template.default_resource_limits)
+      @base_scope_depth    = 0
+      @interrupts          = []
+      @filters             = []
+      @global_filter       = nil
+      @disabled_tags       = {}
 
       self.exception_renderer = Template.default_exception_renderer
       if rethrow_errors
-        self.exception_renderer = ->(e) { raise }
+        self.exception_renderer = Liquid::RAISE_EXCEPTION_LAMBDA
       end
 
-      @interrupts = []
-      @filters = []
-      @global_filter = nil
+      yield self if block_given?
+
+      # Do this last, since it could result in this object being passed to a Proc in the environment
+      squash_instance_assigns_with_environments
     end
+    # rubocop:enable Metrics/ParameterLists
 
     def warnings
       @warnings ||= []
     end
 
     def strainer
-      @strainer ||= Strainer.create(self, @filters)
+      @strainer ||= StrainerFactory.create(self, @filters)
     end
 
     # Adds filters to this context.
@@ -77,7 +91,7 @@ module Liquid
     def handle_error(e, line_number = nil)
       e = internal_error unless e.is_a?(Liquid::Error)
       e.template_name ||= template_name
-      e.line_number ||= line_number
+      e.line_number   ||= line_number
       errors.push(e)
       exception_renderer.call(e).to_s
     end
@@ -89,7 +103,7 @@ module Liquid
     # Push new local scope on the stack. use <tt>Context#stack</tt> instead
     def push(new_scope = {})
       @scopes.unshift(new_scope)
-      raise StackLevelError, "Nesting too deep".freeze if @scopes.length > 100
+      check_overflow
     end
 
     # Merge a hash of variables in the current local scope
@@ -110,20 +124,32 @@ module Liquid
     #      context['var'] = 'hi'
     #   end
     #
-    #   context['var]  #=> nil
-    def stack(new_scope = nil)
-      old_stack_used = @this_stack_used
-      if new_scope
-        push(new_scope)
-        @this_stack_used = true
-      else
-        @this_stack_used = false
-      end
-
+    #   context['var']  #=> nil
+    def stack(new_scope = {})
+      push(new_scope)
       yield
     ensure
-      pop if @this_stack_used
-      @this_stack_used = old_stack_used
+      pop
+    end
+
+    # Creates a new context inheriting resource limits, filters, environment etc.,
+    # but with an isolated scope.
+    def new_isolated_subcontext
+      check_overflow
+
+      self.class.build(
+        resource_limits: resource_limits,
+        static_environments: static_environments,
+        registers: StaticRegisters.new(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
+        subcontext.disabled_tags = @disabled_tags
+      end
     end
 
     def clear_instance_assigns
@@ -132,10 +158,6 @@ module Liquid
 
     # Only allow String, Numeric, Hash, Array, Proc, Boolean or <tt>Liquid::Drop</tt>
     def []=(key, value)
-      unless @this_stack_used
-        @this_stack_used = true
-        push({})
-      end
       @scopes[0][key] = value
     end
 
@@ -164,24 +186,14 @@ 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 = nil
-
-      if scope.nil?
-        @environments.each do |e|
-          variable = lookup_and_evaluate(e, key, raise_on_not_found: raise_on_not_found)
-          unless variable.nil?
-            scope = e
-            break
-          end
-        end
+      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)
       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         = variable.to_liquid
       variable.context = self if variable.respond_to?(:context=)
 
       variable
@@ -195,14 +207,59 @@ module Liquid
       value = obj[key]
 
       if value.is_a?(Proc) && obj.respond_to?(:[]=)
-        obj[key] = (value.arity == 0) ? value.call : value.call(self)
+        obj[key] = value.arity == 0 ? value.call : value.call(self)
       else
         value
       end
     end
 
+    def with_disabled_tags(tag_names)
+      tag_names.each do |name|
+        @disabled_tags[name] = @disabled_tags.fetch(name, 0) + 1
+      end
+      yield
+    ensure
+      tag_names.each do |name|
+        @disabled_tags[name] -= 1
+      end
+    end
+
+    def tag_disabled?(tag_name)
+      @disabled_tags.fetch(tag_name, 0) > 0
+    end
+
+    protected
+
+    attr_writer :base_scope_depth, :warnings, :errors, :strainer, :filters, :disabled_tags
+
     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" 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/document.rb

@@ -1,26 +1,64 @@
+# frozen_string_literal: true
+
 module Liquid
-  class Document < BlockBody
+  class Document
     def self.parse(tokens, parse_context)
-      doc = new
+      doc = new(parse_context)
       doc.parse(tokens, parse_context)
       doc
     end
 
-    def parse(tokens, parse_context)
-      super do |end_tag_name, end_tag_params|
-        unknown_tag(end_tag_name, parse_context) if end_tag_name
+    attr_reader :parse_context, :body
+
+    def initialize(parse_context)
+      @parse_context = parse_context
+      @body = new_body
+    end
+
+    def nodelist
+      @body.nodelist
+    end
+
+    def parse(tokenizer, parse_context)
+      while parse_body(tokenizer)
       end
+      @body.freeze
     rescue SyntaxError => e
       e.line_number ||= parse_context.line_number
       raise
     end
 
-    def unknown_tag(tag, parse_context)
+    def unknown_tag(tag, _markup, _tokenizer)
       case tag
-      when 'else'.freeze, 'end'.freeze
-        raise SyntaxError.new(parse_context.locale.t("errors.syntax.unexpected_outer_tag".freeze, tag: tag))
+      when 'else', 'end'
+        raise SyntaxError, parse_context.locale.t("errors.syntax.unexpected_outer_tag", tag: tag)
       else
-        raise SyntaxError.new(parse_context.locale.t("errors.syntax.unknown_tag".freeze, tag: tag))
+        raise SyntaxError, parse_context.locale.t("errors.syntax.unknown_tag", tag: tag)
+      end
+    end
+
+    def render_to_output_buffer(context, output)
+      @body.render_to_output_buffer(context, output)
+    end
+
+    def render(context)
+      render_to_output_buffer(context, +'')
+    end
+
+    private
+
+    def new_body
+      parse_context.new_block_body
+    end
+
+    def parse_body(tokenizer)
+      @body.parse(tokenizer, parse_context) do |unknown_tag_name, unknown_tag_markup|
+        if unknown_tag_name
+          unknown_tag(unknown_tag_name, unknown_tag_markup, tokenizer)
+          true
+        else
+          false
+        end
       end
     end
   end

lib/liquid/drop.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'set'
 
 module Liquid
@@ -25,7 +27,7 @@ module Liquid
 
     # Catch all for the method
     def liquid_method_missing(method)
-      return nil unless @context && @context.strict_variables
+      return nil unless @context&.strict_variables
       raise Liquid::UndefinedDropMethod, "undefined method #{method}"
     end
 
@@ -67,7 +69,7 @@ module Liquid
 
         if include?(Enumerable)
           blacklist += Enumerable.public_instance_methods
-          blacklist -= [:sort, :count, :first, :min, :max, :include?]
+          blacklist -= [:sort, :count, :first, :min, :max]
         end
 
         whitelist = [:to_liquid] + (public_instance_methods - blacklist)

lib/liquid/errors.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Error < ::StandardError
     attr_accessor :line_number
@@ -5,7 +7,7 @@ module Liquid
     attr_accessor :markup_context
 
     def to_s(with_prefix = true)
-      str = ""
+      str = +""
       str << message_prefix if with_prefix
       str << super()
 
@@ -20,11 +22,11 @@ module Liquid
     private
 
     def message_prefix
-      str = ""
-      if is_a?(SyntaxError)
-        str << "Liquid syntax error"
+      str = +""
+      str << if is_a?(SyntaxError)
+        "Liquid syntax error"
       else
-        str << "Liquid error"
+        "Liquid error"
       end
 
       if line_number
@@ -38,19 +40,19 @@ module Liquid
     end
   end
 
-  ArgumentError = Class.new(Error)
-  ContextError = Class.new(Error)
-  FileSystemError = Class.new(Error)
-  StandardError = Class.new(Error)
-  SyntaxError = Class.new(Error)
-  StackLevelError = Class.new(Error)
-  TaintedError = Class.new(Error)
-  MemoryError = Class.new(Error)
-  ZeroDivisionError = Class.new(Error)
-  FloatDomainError = Class.new(Error)
-  UndefinedVariable = Class.new(Error)
+  ArgumentError       = Class.new(Error)
+  ContextError        = Class.new(Error)
+  FileSystemError     = Class.new(Error)
+  StandardError       = Class.new(Error)
+  SyntaxError         = Class.new(Error)
+  StackLevelError     = Class.new(Error)
+  MemoryError         = Class.new(Error)
+  ZeroDivisionError   = Class.new(Error)
+  FloatDomainError    = Class.new(Error)
+  UndefinedVariable   = Class.new(Error)
   UndefinedDropMethod = Class.new(Error)
-  UndefinedFilter = Class.new(Error)
+  UndefinedFilter     = Class.new(Error)
   MethodOverrideError = Class.new(Error)
-  InternalError = Class.new(Error)
+  DisabledError       = Class.new(Error)
+  InternalError       = Class.new(Error)
 end

lib/liquid/expression.rb

@@ -1,41 +1,41 @@
+# frozen_string_literal: true
+
 module Liquid
   class Expression
-    class MethodLiteral
-      attr_reader :method_name, :to_s
-
-      def initialize(method_name, to_s)
-        @method_name = method_name
-        @to_s = to_s
-      end
-
-      def to_liquid
-        to_s
-      end
-    end
-
     LITERALS = {
-      nil => nil, 'nil'.freeze => nil, 'null'.freeze => nil, ''.freeze => nil,
-      'true'.freeze  => true,
-      'false'.freeze => false,
-      'blank'.freeze => MethodLiteral.new(:blank?, '').freeze,
-      'empty'.freeze => MethodLiteral.new(:empty?, '').freeze
-    }
+      nil => nil, 'nil' => nil, 'null' => nil, '' => nil,
+      'true' => true,
+      'false' => false,
+      'blank' => '',
+      'empty' => ''
+    }.freeze
+
+    INTEGERS_REGEX       = /\A(-?\d+)\z/
+    FLOATS_REGEX         = /\A(-?\d[\d\.]+)\z/
+
+    # Use an atomic group (?>...) to avoid pathological backtracing from
+    # malicious input as described in https://github.com/Shopify/liquid/issues/1357
+    RANGES_REGEX         = /\A\(\s*(?>(\S+)\s*\.\.)\s*(\S+)\s*\)\z/
 
     def self.parse(markup)
-      if LITERALS.key?(markup)
-        LITERALS[markup]
+      return nil unless markup
+
+      markup = markup.strip
+      if (markup.start_with?('"') && markup.end_with?('"')) ||
+         (markup.start_with?("'") && markup.end_with?("'"))
+        return markup[1..-2]
+      end
+
+      case markup
+      when INTEGERS_REGEX
+        Regexp.last_match(1).to_i
+      when RANGES_REGEX
+        RangeLookup.parse(Regexp.last_match(1), Regexp.last_match(2))
+      when FLOATS_REGEX
+        Regexp.last_match(1).to_f
       else
-        case markup
-        when /\A'(.*)'\z/m # Single quoted strings
-          $1
-        when /\A"(.*)"\z/m # Double quoted strings
-          $1
-        when /\A(-?\d+)\z/ # Integer and floats
-          $1.to_i
-        when /\A\((\S+)\.\.(\S+)\)\z/ # Ranges
-          RangeLookup.parse($1, $2)
-        when /\A(-?\d[\d\.]+)\z/ # Floats
-          $1.to_f
+        if LITERALS.key?(markup)
+          LITERALS[markup]
         else
           VariableLookup.parse(markup)
         end

lib/liquid/extensions.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'time'
 require 'date'
 
@@ -7,6 +9,12 @@ class String # :nodoc:
   end
 end
 
+class Symbol # :nodoc:
+  def to_liquid
+    to_s
+  end
+end
+
 class Array # :nodoc:
   def to_liquid
     self

lib/liquid/file_system.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # A Liquid file system is a way to let your templates retrieve other templates for use with the include tag.
   #
@@ -44,8 +46,8 @@ module Liquid
   class LocalFileSystem
     attr_accessor :root
 
-    def initialize(root, pattern = "_%s.liquid".freeze)
-      @root = root
+    def initialize(root, pattern = "_%s.liquid")
+      @root    = root
       @pattern = pattern
     end
 
@@ -57,9 +59,9 @@ module Liquid
     end
 
     def full_path(template_path)
-      raise FileSystemError, "Illegal template name '#{template_path}'" unless template_path =~ /\A[^.\/][a-zA-Z0-9_\/]+\z/
+      raise FileSystemError, "Illegal template name '#{template_path}'" unless %r{\A[^./][a-zA-Z0-9_/]+\z}.match?(template_path)
 
-      full_path = if template_path.include?('/'.freeze)
+      full_path = if template_path.include?('/')
         File.join(root, File.dirname(template_path), @pattern % File.basename(template_path))
       else
         File.join(root, @pattern % template_path)

lib/liquid/forloop_drop.rb

@@ -1,13 +1,20 @@
+# frozen_string_literal: true
+
 module Liquid
   class ForloopDrop < Drop
     def initialize(name, length, parentloop)
-      @name = name
-      @length = length
+      @name       = name
+      @length     = length
       @parentloop = parentloop
-      @index = 0
+      @index      = 0
     end
 
-    attr_reader :name, :length, :parentloop
+    attr_reader :length, :parentloop
+
+    def name
+      Usage.increment('forloop_drop_name')
+      @name
+    end
 
     def index
       @index + 1

lib/liquid/i18n.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'yaml'
 
 module Liquid
@@ -26,13 +28,13 @@ module Liquid
     def interpolate(name, vars)
       name.gsub(/%\{(\w+)\}/) do
         # raise TranslationError, "Undefined key #{$1} for interpolation in translation #{name}"  unless vars[$1.to_sym]
-        "#{vars[$1.to_sym]}"
+        (vars[Regexp.last_match(1).to_sym]).to_s
       end
     end
 
     def deep_fetch_translation(name)
-      name.split('.'.freeze).reduce(locale) do |level, cur|
-        level[cur] or raise TranslationError, "Translation for #{name} does not exist in locale #{path}"
+      name.split('.').reduce(locale) do |level, cur|
+        level[cur] || raise(TranslationError, "Translation for #{name} does not exist in locale #{path}")
       end
     end
   end

lib/liquid/interrupts.rb

@@ -1,10 +1,12 @@
+# frozen_string_literal: true
+
 module Liquid
   # An interrupt is any command that breaks processing of a block (ex: a for loop).
   class Interrupt
     attr_reader :message
 
     def initialize(message = nil)
-      @message = message || "interrupt".freeze
+      @message = message || "interrupt"
     end
   end
 

lib/liquid/lexer.rb

@@ -1,24 +1,27 @@
+# frozen_string_literal: true
+
 require "strscan"
 module Liquid
   class Lexer
     SPECIALS = {
-      '|'.freeze => :pipe,
-      '.'.freeze => :dot,
-      ':'.freeze => :colon,
-      ','.freeze => :comma,
-      '['.freeze => :open_square,
-      ']'.freeze => :close_square,
-      '('.freeze => :open_round,
-      ')'.freeze => :close_round,
-      '?'.freeze => :question,
-      '-'.freeze => :dash
-    }
-    IDENTIFIER = /[a-zA-Z_][\w-]*\??/
+      '|' => :pipe,
+      '.' => :dot,
+      ':' => :colon,
+      ',' => :comma,
+      '[' => :open_square,
+      ']' => :close_square,
+      '(' => :open_round,
+      ')' => :close_round,
+      '?' => :question,
+      '-' => :dash,
+    }.freeze
+    IDENTIFIER            = /[a-zA-Z_][\w-]*\??/
     SINGLE_STRING_LITERAL = /'[^\']*'/
     DOUBLE_STRING_LITERAL = /"[^\"]*"/
-    NUMBER_LITERAL = /-?\d+(\.\d+)?/
-    DOTDOT = /\.\./
-    COMPARISON_OPERATOR = /==|!=|<>|<=?|>=?|contains(?=\s)/
+    NUMBER_LITERAL        = /-?\d+(\.\d+)?/
+    DOTDOT                = /\.\./
+    COMPARISON_OPERATOR   = /==|!=|<>|<=?|>=?|contains(?=\s)/
+    WHITESPACE_OR_NOTHING = /\s*/
 
     def initialize(input)
       @ss = StringScanner.new(input)
@@ -28,18 +31,23 @@ module Liquid
       @output = []
 
       until @ss.eos?
-        @ss.skip(/\s*/)
+        @ss.skip(WHITESPACE_OR_NOTHING)
         break if @ss.eos?
-        tok = case
-        when t = @ss.scan(COMPARISON_OPERATOR) then [:comparison, t]
-        when t = @ss.scan(SINGLE_STRING_LITERAL) then [:string, t]
-        when t = @ss.scan(DOUBLE_STRING_LITERAL) then [:string, t]
-        when t = @ss.scan(NUMBER_LITERAL) then [:number, t]
-        when t = @ss.scan(IDENTIFIER) then [:id, t]
-        when t = @ss.scan(DOTDOT) then [:dotdot, t]
+        tok      = if (t = @ss.scan(COMPARISON_OPERATOR))
+          [:comparison, t]
+        elsif (t = @ss.scan(SINGLE_STRING_LITERAL))
+          [:string, t]
+        elsif (t = @ss.scan(DOUBLE_STRING_LITERAL))
+          [:string, t]
+        elsif (t = @ss.scan(NUMBER_LITERAL))
+          [:number, t]
+        elsif (t = @ss.scan(IDENTIFIER))
+          [:id, t]
+        elsif (t = @ss.scan(DOTDOT))
+          [:dotdot, t]
         else
-          c = @ss.getch
-          if s = SPECIALS[c]
+          c     = @ss.getch
+          if (s = SPECIALS[c])
             [s, c]
           else
             raise SyntaxError, "Unexpected character #{c}"

lib/liquid/locales/en.yml

@@ -14,13 +14,15 @@
       if: "Syntax Error in tag 'if' - Valid syntax: if [expression]"
       include: "Error in tag 'include' - Valid syntax: include '[template]' (with|for) [object|collection]"
       unknown_tag: "Unknown tag '%{tag}'"
-      invalid_delimiter: "'end' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
+      invalid_delimiter: "'%{tag}' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
       unexpected_else: "%{block_name} tag does not expect 'else' tag"
       unexpected_outer_tag: "Unexpected outer '%{tag}' tag"
       tag_termination: "Tag '%{token}' was not properly terminated with regexp: %{tag_end}"
       variable_termination: "Variable '%{token}' was not properly terminated with regexp: %{tag_end}"
       tag_never_closed: "'%{block_name}' tag was never closed"
-      meta_syntax_error: "Liquid syntax error: #{e.message}"
       table_row: "Syntax Error in 'table_row loop' - Valid syntax: table_row [item] in [collection] cols=3"
+      render: "Syntax error in tag 'render' - Template name must be a quoted string"
     argument:
       include: "Argument error in tag 'include' - Illegal template name"
+    disabled:
+      tag: "usage is not allowed in this context"

lib/liquid/parse_context.rb

@@ -1,12 +1,17 @@
+# frozen_string_literal: true
+
 module Liquid
   class ParseContext
-    attr_accessor :locale, :line_number, :trim_whitespace
+    attr_accessor :locale, :line_number, :trim_whitespace, :depth
     attr_reader :partial, :warnings, :error_mode
 
     def initialize(options = {})
       @template_options = options ? options.dup : {}
-      @locale = @template_options[:locale] ||= I18n.new
+
+      @locale   = @template_options[:locale] ||= I18n.new
       @warnings = []
+
+      self.depth   = 0
       self.partial = false
     end
 
@@ -14,11 +19,23 @@ module Liquid
       @options[option_key]
     end
 
+    def new_block_body
+      Liquid::BlockBody.new
+    end
+
+    def new_tokenizer(markup, start_line_number: nil, for_liquid_tag: false)
+      Tokenizer.new(markup, line_number: start_line_number, for_liquid_tag: for_liquid_tag)
+    end
+
+    def parse_expression(markup)
+      Expression.parse(markup)
+    end
+
     def partial=(value)
       @partial = value
       @options = value ? partial_options : @template_options
+
       @error_mode = @options[:error_mode] || Template.error_mode
-      value
     end
 
     def partial_options
@@ -27,7 +44,7 @@ module Liquid
         if dont_pass == true
           { locale: locale }
         elsif dont_pass.is_a?(Array)
-          @template_options.reject { |k, v| dont_pass.include?(k) }
+          @template_options.reject { |k, _v| dont_pass.include?(k) }
         else
           @template_options
         end

lib/liquid/parse_tree_visitor.rb

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

lib/liquid/parser.rb

@@ -1,9 +1,11 @@
+# frozen_string_literal: true
+
 module Liquid
   class Parser
     def initialize(input)
-      l = Lexer.new(input)
+      l       = Lexer.new(input)
       @tokens = l.tokenize
-      @p = 0 # pointer to current location
+      @p      = 0 # pointer to current location
     end
 
     def jump(point)
@@ -46,11 +48,18 @@ module Liquid
 
     def expression
       token = @tokens[@p]
-      if token[0] == :id
-        variable_signature
-      elsif [:string, :number].include? token[0]
+      case token[0]
+      when :id
+        str = consume
+        str << variable_lookups
+      when :open_square
+        str = consume
+        str << expression
+        str << consume(:close_square)
+        str << variable_lookups
+      when :string, :number
         consume
-      elsif token.first == :open_round
+      when :open_round
         consume
         first = expression
         consume(:dotdot)
@@ -63,26 +72,29 @@ module Liquid
     end
 
     def argument
-      str = ""
+      str = +""
       # might be a keyword argument (identifier: expression)
       if look(:id) && look(:colon, 1)
-        str << consume << consume << ' '.freeze
+        str << consume << consume << ' '
       end
 
       str << expression
       str
     end
 
-    def variable_signature
-      str = consume(:id)
-      while look(:open_square)
-        str << consume
-        str << expression
-        str << consume(:close_square)
-      end
-      if look(:dot)
-        str << consume
-        str << variable_signature
+    def variable_lookups
+      str = +""
+      loop do
+        if look(:open_square)
+          str << consume
+          str << expression
+          str << consume(:close_square)
+        elsif look(:dot)
+          str << consume
+          str << consume(:id)
+        else
+          break
+        end
       end
       str
     end

lib/liquid/parser_switching.rb

@@ -1,15 +1,29 @@
+# frozen_string_literal: true
+
 module Liquid
   module ParserSwitching
+    def strict_parse_with_error_mode_fallback(markup)
+      strict_parse_with_error_context(markup)
+    rescue SyntaxError => e
+      case parse_context.error_mode
+      when :strict
+        raise
+      when :warn
+        parse_context.warnings << e
+      end
+      lax_parse(markup)
+    end
+
     def parse_with_selected_parser(markup)
       case parse_context.error_mode
       when :strict then strict_parse_with_error_context(markup)
       when :lax    then lax_parse(markup)
       when :warn
         begin
-          return strict_parse_with_error_context(markup)
+          strict_parse_with_error_context(markup)
         rescue SyntaxError => e
           parse_context.warnings << e
-          return lax_parse(markup)
+          lax_parse(markup)
         end
       end
     end
@@ -19,7 +33,7 @@ module Liquid
     def strict_parse_with_error_context(markup)
       strict_parse(markup)
     rescue SyntaxError => e
-      e.line_number = line_number
+      e.line_number    = line_number
       e.markup_context = markup_context(markup)
       raise e
     end

lib/liquid/partial_cache.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+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
+
+      template_factory = (context.registers[:template_factory] ||= Liquid::TemplateFactory.new)
+      template = template_factory.for(template_name)
+
+      partial = template.parse(source, parse_context)
+      cached_partials[template_name] = partial
+    ensure
+      parse_context.partial = false
+    end
+  end
+end

lib/liquid/profiler.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'liquid/profiler/hooks'
 
 module Liquid
@@ -23,7 +25,7 @@ module Liquid
   #     node.code
   #
   #     # Which template and line number of this node.
-  #     # If top level, this will be "<root>".
+  #     # The top-level template name is `nil` by default, but can be set in the Liquid::Context before rendering.
   #     node.partial
   #     node.line_number
   #
@@ -44,115 +46,94 @@ module Liquid
     include Enumerable
 
     class Timing
-      attr_reader :code, :partial, :line_number, :children
+      attr_reader :code, :template_name, :line_number, :children
+      attr_accessor :total_time
+      alias_method :render_time, :total_time
+      alias_method :partial, :template_name
 
-      def initialize(node, partial)
-        @code        = node.respond_to?(:raw) ? node.raw : node
-        @partial     = partial
-        @line_number = node.respond_to?(:line_number) ? node.line_number : nil
-        @children    = []
+      def initialize(code: nil, template_name: nil, line_number: nil)
+        @code = code
+        @template_name = template_name
+        @line_number = line_number
+        @children = []
       end
 
-      def self.start(node, partial)
-        new(node, partial).tap(&:start)
-      end
-
-      def start
-        @start_time = Time.now
-      end
-
-      def finish
-        @end_time = Time.now
-      end
-
-      def render_time
-        @end_time - @start_time
+      def self_time
+        @self_time ||= begin
+          total_children_time = 0.0
+          @children.each do |child|
+            total_children_time += child.total_time
+          end
+          @total_time - total_children_time
+        end
       end
     end
 
-    def self.profile_node_render(node)
-      if Profiler.current_profile && node.respond_to?(:render)
-        Profiler.current_profile.start_node(node)
-        output = yield
-        Profiler.current_profile.end_node(node)
-        output
-      else
-        yield
-      end
-    end
-
-    def self.profile_children(template_name)
-      if Profiler.current_profile
-        Profiler.current_profile.push_partial(template_name)
-        output = yield
-        Profiler.current_profile.pop_partial
-        output
-      else
-        yield
-      end
-    end
-
-    def self.current_profile
-      Thread.current[:liquid_profiler]
-    end
+    attr_reader :total_time
+    alias_method :total_render_time, :total_time
 
     def initialize
-      @partial_stack = ["<root>"]
-
-      @root_timing = Timing.new("", current_partial)
-      @timing_stack = [@root_timing]
-
-      @render_start_at = Time.now
-      @render_end_at = @render_start_at
+      @root_children = []
+      @current_children = nil
+      @total_time = 0.0
     end
 
-    def start
-      Thread.current[:liquid_profiler] = self
-      @render_start_at = Time.now
+    def profile(template_name, &block)
+      # nested renders are done from a tag that already has a timing node
+      return yield if @current_children
+
+      root_children = @root_children
+      render_idx = root_children.length
+      begin
+        @current_children = root_children
+        profile_node(template_name, &block)
+      ensure
+        @current_children = nil
+        if (timing = root_children[render_idx])
+          @total_time += timing.total_time
+        end
+      end
     end
 
-    def stop
-      Thread.current[:liquid_profiler] = nil
-      @render_end_at = Time.now
-    end
-
-    def total_render_time
-      @render_end_at - @render_start_at
+    def children
+      children = @root_children
+      if children.length == 1
+        children.first.children
+      else
+        children
+      end
     end
 
     def each(&block)
-      @root_timing.children.each(&block)
+      children.each(&block)
     end
 
     def [](idx)
-      @root_timing.children[idx]
+      children[idx]
     end
 
     def length
-      @root_timing.children.length
+      children.length
     end
 
-    def start_node(node)
-      @timing_stack.push(Timing.start(node, current_partial))
+    def profile_node(template_name, code: nil, line_number: nil)
+      timing = Timing.new(code: code, template_name: template_name, line_number: line_number)
+      parent_children = @current_children
+      start_time = monotonic_time
+      begin
+        @current_children = timing.children
+        yield
+      ensure
+        @current_children = parent_children
+        timing.total_time = monotonic_time - start_time
+        parent_children << timing
+      end
     end
 
-    def end_node(_node)
-      timing = @timing_stack.pop
-      timing.finish
+    private
 
-      @timing_stack.last.children << timing
-    end
-
-    def current_partial
-      @partial_stack.last
-    end
-
-    def push_partial(partial_name)
-      @partial_stack.push(partial_name)
-    end
-
-    def pop_partial
-      @partial_stack.pop
+    def monotonic_time
+      Process.clock_gettime(Process::CLOCK_MONOTONIC)
     end
   end
 end

lib/liquid/profiler/hooks.rb

@@ -1,23 +1,35 @@
+# frozen_string_literal: true
+
 module Liquid
-  class BlockBody
-    def render_node_with_profiling(node, context)
-      Profiler.profile_node_render(node) do
-        render_node_without_profiling(node, context)
+  module BlockBodyProfilingHook
+    def render_node(context, output, node)
+      if (profiler = context.profiler)
+        profiler.profile_node(context.template_name, code: node.raw, line_number: node.line_number) do
+          super
+        end
+      else
+        super
       end
     end
-
-    alias_method :render_node_without_profiling, :render_node
-    alias_method :render_node, :render_node_with_profiling
   end
+  BlockBody.prepend(BlockBodyProfilingHook)
 
-  class Include < Tag
-    def render_with_profiling(context)
-      Profiler.profile_children(context.evaluate(@template_name_expr).to_s) do
-        render_without_profiling(context)
-      end
+  module DocumentProfilingHook
+    def render_to_output_buffer(context, output)
+      return super unless context.profiler
+      context.profiler.profile(context.template_name) { super }
     end
-
-    alias_method :render_without_profiling, :render
-    alias_method :render, :render_with_profiling
   end
+  Document.prepend(DocumentProfilingHook)
+
+  module ContextProfilingHook
+    attr_accessor :profiler
+
+    def new_isolated_subcontext
+      new_context = super
+      new_context.profiler = profiler
+      new_context
+    end
+  end
+  Context.prepend(ContextProfilingHook)
 end

lib/liquid/range_lookup.rb

@@ -1,8 +1,10 @@
+# frozen_string_literal: true
+
 module Liquid
   class RangeLookup
     def self.parse(start_markup, end_markup)
       start_obj = Expression.parse(start_markup)
-      end_obj = Expression.parse(end_markup)
+      end_obj   = Expression.parse(end_markup)
       if start_obj.respond_to?(:evaluate) || end_obj.respond_to?(:evaluate)
         new(start_obj, end_obj)
       else
@@ -10,14 +12,16 @@ module Liquid
       end
     end
 
+    attr_reader :start_obj, :end_obj
+
     def initialize(start_obj, end_obj)
       @start_obj = start_obj
-      @end_obj = end_obj
+      @end_obj   = end_obj
     end
 
     def evaluate(context)
       start_int = to_integer(context.evaluate(@start_obj))
-      end_int = to_integer(context.evaluate(@end_obj))
+      end_int   = to_integer(context.evaluate(@end_obj))
       start_int..end_int
     end
 
@@ -33,5 +37,11 @@ module Liquid
         Utils.to_integer(input)
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.start_obj, @node.end_obj]
+      end
+    end
   end
 end

lib/liquid/register.rb

@@ -0,0 +1,6 @@
+# frozen_string_literal: true
+
+module Liquid
+  class Register
+  end
+end

lib/liquid/resource_limits.rb

@@ -1,23 +1,62 @@
+# frozen_string_literal: true
+
 module Liquid
   class ResourceLimits
-    attr_accessor :render_length, :render_score, :assign_score,
-      :render_length_limit, :render_score_limit, :assign_score_limit
+    attr_accessor :render_length_limit, :render_score_limit, :assign_score_limit
+    attr_reader :render_score, :assign_score
 
     def initialize(limits)
       @render_length_limit = limits[:render_length_limit]
-      @render_score_limit = limits[:render_score_limit]
-      @assign_score_limit = limits[:assign_score_limit]
+      @render_score_limit  = limits[:render_score_limit]
+      @assign_score_limit  = limits[:assign_score_limit]
       reset
     end
 
+    def increment_render_score(amount)
+      @render_score += amount
+      raise_limits_reached if @render_score_limit && @render_score > @render_score_limit
+    end
+
+    def increment_assign_score(amount)
+      @assign_score += amount
+      raise_limits_reached if @assign_score_limit && @assign_score > @assign_score_limit
+    end
+
+    # update either render_length or assign_score based on whether or not the writes are captured
+    def increment_write_score(output)
+      if (last_captured = @last_capture_length)
+        captured = output.bytesize
+        increment = captured - last_captured
+        @last_capture_length = captured
+        increment_assign_score(increment)
+      elsif @render_length_limit && output.bytesize > @render_length_limit
+        raise_limits_reached
+      end
+    end
+
+    def raise_limits_reached
+      @reached_limit = true
+      raise MemoryError, "Memory limits exceeded"
+    end
+
     def reached?
-      (@render_length_limit && @render_length > @render_length_limit) ||
-        (@render_score_limit && @render_score > @render_score_limit) ||
-        (@assign_score_limit && @assign_score > @assign_score_limit)
+      @reached_limit
     end
 
     def reset
-      @render_length = @render_score = @assign_score = 0
+      @reached_limit = false
+      @last_capture_length = nil
+      @render_score = @assign_score = 0
+    end
+
+    def with_capture
+      old_capture_length = @last_capture_length
+      begin
+        @last_capture_length = 0
+        yield
+      ensure
+        @last_capture_length = old_capture_length
+      end
     end
   end
 end

lib/liquid/standardfilters.rb

@@ -1,16 +1,26 @@
+# frozen_string_literal: true
+
 require 'cgi'
+require 'base64'
 require 'bigdecimal'
 
 module Liquid
   module StandardFilters
+    MAX_INT = (1 << 31) - 1
     HTML_ESCAPE = {
-      '&'.freeze => '&amp;'.freeze,
-      '>'.freeze => '&gt;'.freeze,
-      '<'.freeze => '&lt;'.freeze,
-      '"'.freeze => '&quot;'.freeze,
-      "'".freeze => '&#39;'.freeze
-    }
+      '&' => '&amp;',
+      '>' => '&gt;',
+      '<' => '&lt;',
+      '"' => '&quot;',
+      "'" => '&#39;',
+    }.freeze
     HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+));)/
+    STRIP_HTML_BLOCKS       = Regexp.union(
+      %r{<script.*?</script>}m,
+      /<!--.*?-->/m,
+      %r{<style.*?</style>}m
+    )
+    STRIP_HTML_TAGS = /<.*?>/m
 
     # Return the size of an array or of an string
     def size(input)
@@ -18,22 +28,49 @@ module Liquid
     end
 
     # convert an input string to DOWNCASE
+    #
+    # @public_docs
+    # @type filter
+    # @summary Converts a string into lowercase.
+    # @category string
+    # @syntax {{ string | downcase }}
+    # @return string
     def downcase(input)
       input.to_s.downcase
     end
 
     # convert an input string to UPCASE
+    #
+    # @public_docs
+    # @type filter
+    # @summary Converts a string into uppercase.
+    # @category string
+    # @syntax {{ string | upcase }}
+    # @return string
     def upcase(input)
       input.to_s.upcase
     end
 
-    # capitalize words in the input centence
+    # capitalize words in the input sentence
+    #
+    # @public_docs
+    # @type filter
+    # @summary Capitalizes the first word in a string.
+    # @category string
+    # @syntax {{ string | capitalize }}
+    # @return string
     def capitalize(input)
       input.to_s.capitalize
     end
 
+    # @public_docs
+    # @type filter
+    # @summary Escapes a string.
+    # @category string
+    # @syntax {{ string | escape }}
+    # @return string
     def escape(input)
-      CGI.escapeHTML(input).untaint unless input.nil?
+      CGI.escapeHTML(input.to_s) unless input.nil?
     end
     alias_method :h, :escape
 
@@ -42,11 +79,63 @@ module Liquid
     end
 
     def url_encode(input)
-      CGI.escape(input) unless input.nil?
+      CGI.escape(input.to_s) unless input.nil?
     end
 
     def url_decode(input)
-      CGI.unescape(input) unless input.nil?
+      return if input.nil?
+
+      result = CGI.unescape(input.to_s)
+      raise Liquid::ArgumentError, "invalid byte sequence in #{result.encoding}" unless result.valid_encoding?
+
+      result
+    end
+
+    # @public_docs
+    # @type filter
+    # @title base64_encode
+    # @summary Encodes a string into Base64.
+    # @category string
+    # @syntax {{ string | base64_encode }}
+    # @return string
+    def base64_encode(input)
+      Base64.strict_encode64(input.to_s)
+    end
+
+    # @public_docs
+    # @type filter
+    # @summary Decodes a string from Base64.
+    # @category string
+    # @syntax {{ string | base64_decode }}
+    # @return string
+    def base64_decode(input)
+      Base64.strict_decode64(input.to_s)
+    rescue ::ArgumentError
+      raise Liquid::ArgumentError, "invalid base64 provided to base64_decode"
+    end
+
+    # @public_docs
+    # @type filter
+    # @summary Encodes a string into URL-safe Base64
+    # @category string
+    # @syntax {{ string | base64_url_safe_encode }}
+    # @return string
+    # @description
+    #   To produce URL-safe Base64, this filter uses `-`` and `_`` in place of `+`` and `/``.
+    def base64_url_safe_encode(input)
+      Base64.urlsafe_encode64(input.to_s)
+    end
+
+    # @public_docs
+    # @type filter
+    # @summary Decodes a string from URL-safe Base64.
+    # @category string
+    # @syntax {{ string | base64_url_safe_decode }}
+    # @return string
+    def base64_url_safe_decode(input)
+      Base64.urlsafe_decode64(input.to_s)
+    rescue ::ArgumentError
+      raise Liquid::ArgumentError, "invalid base64 provided to base64_url_safe_decode"
     end
 
     def slice(input, offset, length = nil)
@@ -60,24 +149,85 @@ module Liquid
       end
     end
 
-    # Truncate a string down to x characters
-    def truncate(input, length = 50, truncate_string = "...".freeze)
+    # @public_docs
+    # @type filter
+    # @category string
+    # @summary
+    #   Truncates a string down to a specified number of characters.
+    # @description
+    #   By default, an ellipsis (`...`)
+    #   is appended to the truncated string.
+    #
+    #   > Tip:
+    #   > The number of characters in both default and custom ellipses is included in the
+    #   > character count for the truncated string. For example, if you want to truncate a string
+    #   > down to ten characters and use the default ellipsis (`...`), then you should set the
+    #   > character count parameter to `13`.
+    #
+    #   ### Custom ellipsis
+    #
+    #   The `truncate` filter accepts an optional parameter to specify a custom ellipsis to be
+    #   appended to the truncated string.
+    #
+    #   ### No ellipsis
+    #
+    #   If you don't want an ellipsis appended to your truncated string, then you can set the
+    #   ellipsis parameter to a blank string (`''`).
+    # @syntax {{ string | truncate: character_count, ellipsis }}
+    # @required_param character_count [number] The number of characters to include in the truncated string. Includes the characters in the ellipsis.
+    # @optional_param ellipsis [string] The format of the ellipsis appended to the truncated string. Default is `...`. Pass a blank string (`''`) to remove the ellipsis completely.
+    # @return string
+    def truncate(input, length = 50, truncate_string = "...")
       return if input.nil?
       input_str = input.to_s
-      length = Utils.to_integer(length)
+      length    = Utils.to_integer(length)
+
       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] + truncate_string_str : input_str
+
+      input_str.length > length ? input_str[0...l].concat(truncate_string_str) : input_str
     end
 
-    def truncatewords(input, words = 15, truncate_string = "...".freeze)
+    # @public_docs
+    # @type filter
+    # @category string
+    # @summary
+    #   Truncates a string down to a specified number of words.
+    # @description
+    # By default, an ellipsis (`...`) is appended to the truncated string.
+    #
+    #   ### Custom ellipsis
+    #
+    #   The `truncate` filter accepts an optional parameter to specify a custom ellipsis to be
+    #   appended to the truncated string.
+    #
+    #   ### No ellipsis
+    #
+    #   If you don't want an ellipsis appended to your truncated string, then you can set the
+    #   ellipsis parameter to a blank string (`''`).
+    # @syntax {{ string | truncatewords: word_count, ellipsis }}
+    # @required_param word_count [number] The number of words to include in the truncated string. Includes the characters in the ellipsis.
+    # @optional_param ellipsis [string] The format of the ellipsis appended to the truncated string. Default is `...`. Pass a blank string (`''`) to remove the ellipsis completely.
+    # @return string
+    def truncatewords(input, words = 15, truncate_string = "...")
       return if input.nil?
-      wordlist = input.to_s.split
+      input = input.to_s
       words = Utils.to_integer(words)
-      l = words - 1
-      l = 0 if l < 0
-      wordlist.length > l ? wordlist[0..l].join(" ".freeze) + truncate_string.to_s : input
+      words = 1 if words <= 0
+
+      wordlist = begin
+        input.split(" ", words + 1)
+      rescue RangeError
+        raise if words + 1 < MAX_INT
+        # e.g. integer #{words} too big to convert to `int'
+        raise Liquid::ArgumentError, "integer #{words} too big for truncatewords"
+      end
+      return input if wordlist.length <= words
+
+      wordlist.pop
+      wordlist.join(" ").concat(truncate_string.to_s)
     end
 
     # Split input string into an array of substrings separated by given pattern.
@@ -89,50 +239,97 @@ module Liquid
       input.to_s.split(pattern.to_s)
     end
 
+    # @public_docs
+    # @type filter
+    # @category string
+    # @summary
+    #   Strips all whitespace, such as tabs, spaces, and newlines, from the left and right sides of a string.
+    # @syntax {{ string | strip }}
+    # @return string
     def strip(input)
       input.to_s.strip
     end
 
+    # @public_docs
+    # @type filter
+    # @category string
+    # @summary
+    #   Strips all whitespace, such as tabs, spaces, and newlines, from the left side of a string.
+    # @syntax {{ string | lstrip }}
+    # @return string
     def lstrip(input)
       input.to_s.lstrip
     end
 
+    # @public_docs
+    # @type filter
+    # @category string
+    # @summary
+    #   Strips all whitespace, such as tabs, spaces, and newlines, from the right side of a string.
+    # @syntax {{ string | rstrip }}
+    # @return string
     def rstrip(input)
       input.to_s.rstrip
     end
 
+    # @public_docs
+    # @type filter
+    # @category string
+    # @summary
+    #   Strips all HTML tags from a string.
+    # @syntax {{ string | strip_html }}
+    # @return string
     def strip_html(input)
-      empty = ''.freeze
-      input.to_s.gsub(/<script.*?<\/script>/m, empty).gsub(/<!--.*?-->/m, empty).gsub(/<style.*?<\/style>/m, empty).gsub(/<.*?>/m, empty)
+      empty  = ''
+      result = input.to_s.gsub(STRIP_HTML_BLOCKS, empty)
+      result.gsub!(STRIP_HTML_TAGS, empty)
+      result
     end
 
-    # Remove all newlines from the string
+    # @public_docs
+    # @type filter
+    # @category string
+    # @summary
+    #   Strips all line breaks and newlines from a string.
+    # @syntax {{ string | strip_newlines }}
+    # @return string
     def strip_newlines(input)
-      input.to_s.gsub(/\r?\n/, ''.freeze)
+      input.to_s.gsub(/\r?\n/, '')
     end
 
-    # Join elements of the array with certain character between them
-    def join(input, glue = ' '.freeze)
-      InputIterator.new(input).join(glue)
+    # @public_docs
+    # @type filter
+    # @category array
+    # @summary Joins the elements in an array. The result is a single string.
+    # @syntax {{ array | join: ', ' }}
+    # @required_param delimiter [string] The separator to join the array elements with.
+    # @return string
+    def join(input, glue = ' ')
+      InputIterator.new(input, context).join(glue)
     end
 
-    # Sort elements of the array
-    # provide optional property with which to sort an array of hashes or drops
+    # @public_docs
+    # @type filter
+    # @category array
+    # @summary Sorts the elements of an array.
+    # @description The order of the sorted array is case-sensitive.
+    # @syntax {{ array | sort: property }}
+    # @optional_param property [string] The property of the element to sort by.
+    # @return array
     def sort(input, property = nil)
-      ary = InputIterator.new(input)
+      ary = InputIterator.new(input, context)
+
+      return [] if ary.empty?
+
       if property.nil?
-        ary.sort
-      elsif ary.empty? # The next two cases assume a non-empty array.
-        []
-      elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
         ary.sort do |a, b|
-          a = a[property]
-          b = b[property]
-          if a && b
-            a <=> b
-          else
-            a ? -1 : 1
-          end
+          nil_safe_compare(a, b)
+        end
+      elsif ary.all? { |el| el.respond_to?(:[]) }
+        begin
+          ary.sort { |a, b| nil_safe_compare(a[property], b[property]) }
+        rescue TypeError
+          raise_property_error(property)
         end
       end
     end
@@ -140,105 +337,229 @@ module Liquid
     # Sort elements of an array ignoring case if strings
     # provide optional property with which to sort an array of hashes or drops
     def sort_natural(input, property = nil)
-      ary = InputIterator.new(input)
+      ary = InputIterator.new(input, context)
+
+      return [] if ary.empty?
 
       if property.nil?
-        ary.sort { |a, b| a.casecmp(b) }
-      elsif ary.empty? # The next two cases assume a non-empty array.
+        ary.sort do |a, b|
+          nil_safe_casecmp(a, b)
+        end
+      elsif ary.all? { |el| el.respond_to?(:[]) }
+        begin
+          ary.sort { |a, b| nil_safe_casecmp(a[property], b[property]) }
+        rescue TypeError
+          raise_property_error(property)
+        end
+      end
+    end
+
+    # Filter the elements of an array to those with a certain property value.
+    # By default the target is any truthy value.
+    def where(input, property, target_value = nil)
+      ary = InputIterator.new(input, context)
+
+      if ary.empty?
         []
-      elsif ary.first.respond_to?(:[]) && !ary.first[property].nil?
-        ary.sort { |a, b| a[property].casecmp(b[property]) }
+      elsif target_value.nil?
+        ary.select do |item|
+          item[property]
+        rescue TypeError
+          raise_property_error(property)
+        rescue NoMethodError
+          return nil unless item.respond_to?(:[])
+          raise
+        end
+      else
+        ary.select do |item|
+          item[property] == target_value
+        rescue TypeError
+          raise_property_error(property)
+        rescue NoMethodError
+          return nil unless item.respond_to?(:[])
+          raise
+        end
       end
     end
 
     # Remove duplicate elements from an array
     # provide optional property with which to determine uniqueness
     def uniq(input, property = nil)
-      ary = InputIterator.new(input)
+      ary = InputIterator.new(input, context)
 
       if property.nil?
         ary.uniq
       elsif ary.empty? # The next two cases assume a non-empty array.
         []
-      elsif ary.first.respond_to?(:[])
-        ary.uniq{ |a| a[property] }
+      else
+        ary.uniq do |item|
+          item[property]
+        rescue TypeError
+          raise_property_error(property)
+        rescue NoMethodError
+          return nil unless item.respond_to?(:[])
+          raise
+        end
       end
     end
 
-    # Reverse the elements of an array
+    # @public_docs
+    # @type tag
+    # @category array
+    # @summary Reverses the order of the items in an array.
+    # @syntax {{ array | reverse }}
+    # @return array
     def reverse(input)
-      ary = InputIterator.new(input)
+      ary = InputIterator.new(input, context)
       ary.reverse
     end
 
-    # map/collect on a given property
+    # @public_docs
+    # @type tag
+    # @category array
+    # @summary Accepts an array element's property as a parameter and creates an array out of the property value for each array element.
+    # @required_param property [string] The property to extract from the element.
+    # @syntax {{ array | map: 'property' }}
+    # @return array
     def map(input, property)
-      InputIterator.new(input).map do |e|
+      InputIterator.new(input, context).map do |e|
         e = e.call if e.is_a?(Proc)
 
-        if property == "to_liquid".freeze
+        if property == "to_liquid"
           e
         elsif e.respond_to?(:[])
           r = e[property]
           r.is_a?(Proc) ? r.call : r
         end
       end
+    rescue TypeError
+      raise_property_error(property)
     end
 
     # Remove nils within an array
     # provide optional property with which to check for nil
     def compact(input, property = nil)
-      ary = InputIterator.new(input)
+      ary = InputIterator.new(input, context)
 
       if property.nil?
         ary.compact
       elsif ary.empty? # The next two cases assume a non-empty array.
         []
-      elsif ary.first.respond_to?(:[])
-        ary.reject{ |a| a[property].nil? }
+      else
+        ary.reject do |item|
+          item[property].nil?
+        rescue TypeError
+          raise_property_error(property)
+        rescue NoMethodError
+          return nil unless item.respond_to?(:[])
+          raise
+        end
       end
     end
 
-    # Replace occurrences of a string with another
-    def replace(input, string, replacement = ''.freeze)
+    # @public_docs
+    # @summary Replaces all occurrences of a string with a substring.
+    # @type filter
+    # @category string
+    # @syntax {{ string | replace: original_string, replacement_string }}
+    # @required_param original_string [string] The string to replace.
+    # @required_param replacement_string [string] The replacement string.
+    # @return string
+    def replace(input, string, replacement = '')
       input.to_s.gsub(string.to_s, replacement.to_s)
     end
 
     # Replace the first occurrences of a string with another
-    def replace_first(input, string, replacement = ''.freeze)
+    def replace_first(input, string, replacement = '')
       input.to_s.sub(string.to_s, replacement.to_s)
     end
 
-    # remove a substring
-    def remove(input, string)
-      input.to_s.gsub(string.to_s, ''.freeze)
+    # Replace the last occurrences of a string with another
+    def replace_last(input, string, replacement)
+      input = input.to_s
+      string = string.to_s
+      replacement = replacement.to_s
+
+      start_index = input.rindex(string)
+
+      return input unless start_index
+
+      output = input.dup
+      output[start_index, string.length] = replacement
+      output
     end
 
-    # remove the first occurrences of a substring
+    # @public_docs
+    # @summary Removes a substring from a string.
+    # @type filter
+    # @category string
+    # @syntax {{ string | remove: substring }}
+    # @required_param substring [string] The substring to remove from the string.
+    # @return string
+    def remove(input, string)
+      replace(input, string, '')
+    end
+
+    # @public_docs
+    # @summary Removes the first occurrences of a substring.
+    # @type filter
+    # @category string
+    # @syntax {{ string | remove_first: substring }}
+    # @required_param substring [string] The substring to remove from the string.
+    # @return string
     def remove_first(input, string)
-      input.to_s.sub(string.to_s, ''.freeze)
+      replace_first(input, string, '')
+    end
+
+    # remove the last occurences of a substring
+    def remove_last(input, string)
+      replace_last(input, string, '')
     end
 
     # add one string to another
+    #
+    # @public_docs
+    # @type filter
+    # @summary Appends characters to a string.
+    # @category string
+    # @syntax {{ string | append: to_append }}
+    # @required_param to_append [string] characters to append to the original string
+    # @return string
     def append(input, string)
       input.to_s + string.to_s
     end
 
+    # @public_docs
+    # @type filter
+    # @category array
+    # @summary Concatenates (combines) an array with another array.
+    # @description
+    #   The resulting array contains all the elements of the original arrays.
+    #   `concat` won't remove duplicate entries from the concatenated array unless you also use the [`uniq`](/api/liquid/filters/array-filters#uniq) filter.
+    # @syntax {{ first_array | concat: second_array }}
+    # @required_param second_array [array] The array to concatenate with the primary array.
+    # @return array
     def concat(input, array)
       unless array.respond_to?(:to_ary)
-        raise ArgumentError.new("concat filter requires an array argument")
+        raise ArgumentError, "concat filter requires an array argument"
       end
-      InputIterator.new(input).concat(array)
+      InputIterator.new(input, context).concat(array)
     end
 
-    # prepend a string to another
+    # @public_docs
+    # @summary Prepends a string to another string.
+    # @type filter
+    # @category string
+    # @syntax {{ string | prepend: additional_string }}
+    # @required_param  additional_string [string] The string to prepend to the original string.
+    # @return string
     def prepend(input, string)
       string.to_s + input.to_s
     end
 
     # Add <br /> tags in front of all newlines in input string
     def newline_to_br(input)
-      input.to_s.gsub(/\n/, "<br />\n".freeze)
+      input.to_s.gsub(/\r?\n/, "<br />\n")
     end
 
     # Reformat a date using Ruby's core Time#strftime( string ) -> string
@@ -275,63 +596,106 @@ module Liquid
     def date(input, format)
       return input if format.to_s.empty?
 
-      return input unless date = Utils.to_date(input)
+      return input unless (date = Utils.to_date(input))
 
       date.strftime(format.to_s)
     end
 
-    # Get the first element of the passed in array
-    #
-    # Example:
-    #    {{ product.images | first | to_img }}
-    #
+    # @public_docs
+    # @type filter
+    # @category array
+    # @summary Returns the first element of an array.
+    # @syntax {{ array | first }}
     def first(array)
       array.first if array.respond_to?(:first)
     end
 
-    # Get the last element of the passed in array
-    #
-    # Example:
-    #    {{ product.images | last | to_img }}
-    #
+    # @public_docs
+    # @type filter
+    # @category array
+    # @summary Returns the last element of an array, or the last character inside of a string.
+    # @syntax {{ array | last }}
     def last(array)
       array.last if array.respond_to?(:last)
     end
 
-    # absolute value
+    # @public_docs
+    # @syntax {{ number | abs }}
+    # @summary Returns the absolute value of a number.
+    # @type filter
+    # @category math
+    # @return number
+    # @description
+    #   `abs` will also work on a string if the string only contains a number.
     def abs(input)
       result = Utils.to_number(input).abs
       result.is_a?(BigDecimal) ? result.to_f : result
     end
 
-    # addition
+    # @public_docs
+    # @summary Adds a number to an output.
+    # @type filter
+    # @category math
+    # @syntax {{ number | plus: number }}
+    # @required_param number [number] The number to add to the original number.
+    # @return number
     def plus(input, operand)
       apply_operation(input, operand, :+)
     end
 
-    # subtraction
+    # @public_docs
+    # @summary Subtracts a number from an output.
+    # @type filter
+    # @category math
+    # @syntax {{ number | minus: number }}
+    # @return number
     def minus(input, operand)
       apply_operation(input, operand, :-)
     end
 
-    # multiplication
+    # @public_docs
+    # @summary Multiplies an output by a number.
+    # @type filter
+    # @category math
+    # @syntax {{ number | times: number }}
+    # @required_param number [number] The number to multiply the original number by.
+    # @return number
     def times(input, operand)
       apply_operation(input, operand, :*)
     end
 
-    # division
+    # @public_docs
+    # @summary Divides an output by a number. The output is rounded down to the nearest integer.
+    # @type filter
+    # @category math
+    # @syntax {{ number | divided_by: number }}
+    # @return number
     def divided_by(input, operand)
       apply_operation(input, operand, :/)
     rescue ::ZeroDivisionError => e
       raise Liquid::ZeroDivisionError, e.message
     end
 
+    # @public_docs
+    # @summary Divides an output by a number and returns the remainder.
+    # @type filter
+    # @category math
+    # @syntax {{ number | modulo: number }}
+    # @required_param number [number] The number to divide the original number by.
+    # @return number
     def modulo(input, operand)
       apply_operation(input, operand, :%)
     rescue ::ZeroDivisionError => e
       raise Liquid::ZeroDivisionError, e.message
     end
 
+    # @public_docs
+    # @summary Rounds the output to the nearest integer or specified number of decimals.
+    # @type filter
+    # @category math
+    # @syntax {{ number | round }}
+    # @optional_param decimals [number] The number of decimal places to round to.
+    # @return number
     def round(input, n = 0)
       result = Utils.to_number(input).round(Utils.to_number(n))
       result = result.to_f if result.is_a?(BigDecimal)
@@ -341,38 +705,117 @@ module Liquid
       raise Liquid::FloatDomainError, e.message
     end
 
+    # @public_docs
+    # @summary Rounds an output up to the nearest integer.
+    # @type filter
+    # @category math
+    # @syntax {{ number | ceil }}
+    # @return number
     def ceil(input)
       Utils.to_number(input).ceil.to_i
     rescue ::FloatDomainError => e
       raise Liquid::FloatDomainError, e.message
     end
 
+    # @public_docs
+    # @summary Rounds an output down to the nearest integer.
+    # @type filter
+    # @category math
+    # @syntax {{ number | floor }}
+    # @return number
     def floor(input)
       Utils.to_number(input).floor.to_i
     rescue ::FloatDomainError => e
       raise Liquid::FloatDomainError, e.message
     end
 
-    def default(input, default_value = ''.freeze)
-      if !input || input.respond_to?(:empty?) && input.empty?
-        default_value
-      else
-        input
-      end
+    # @public_docs
+    # @summary Limits a number to a minimum value.
+    # @type filter
+    # @category math
+    # @syntax {{ number | at_least: number }}
+    # @required_param number [number] The minimum valid value.
+    # @return number
+    def at_least(input, n)
+      min_value = Utils.to_number(n)
+
+      result = Utils.to_number(input)
+      result = min_value if min_value > result
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
+    # @public_docs
+    # @summary Limits a number to a maximum value.
+    # @type filter
+    # @category math
+    # @syntax {{ number | at_most: number }}
+    # @required_param number [number] The maximum valid value.
+    # @return number
+    def at_most(input, n)
+      max_value = Utils.to_number(n)
+
+      result = Utils.to_number(input)
+      result = max_value if max_value < result
+      result.is_a?(BigDecimal) ? result.to_f : result
+    end
+
+    # Set a default value when the input is nil, false or empty
+    #
+    # Example:
+    #    {{ product.title | default: "No Title" }}
+    #
+    # Use `allow_false` when an input should only be tested against nil or empty and not false.
+    #
+    # Example:
+    #    {{ product.title | default: "No Title", allow_false: true }}
+    #
+    def default(input, default_value = '', options = {})
+      options = {} unless options.is_a?(Hash)
+      false_check = options['allow_false'] ? input.nil? : !Liquid::Utils.to_liquid_value(input)
+      false_check || (input.respond_to?(:empty?) && input.empty?) ? default_value : input
     end
 
     private
 
+    attr_reader :context
+
+    def raise_property_error(property)
+      raise Liquid::ArgumentError, "cannot select the property '#{property}'"
+    end
+
     def apply_operation(input, operand, operation)
       result = Utils.to_number(input).send(operation, Utils.to_number(operand))
       result.is_a?(BigDecimal) ? result.to_f : result
     end
 
+    def nil_safe_compare(a, b)
+      result = a <=> b
+
+      if result
+        result
+      elsif a.nil?
+        1
+      elsif b.nil?
+        -1
+      else
+        raise Liquid::ArgumentError, "cannot sort values of incompatible types"
+      end
+    end
+
+    def nil_safe_casecmp(a, b)
+      if !a.nil? && !b.nil?
+        a.to_s.casecmp(b.to_s)
+      else
+        a.nil? ? 1 : -1
+      end
+    end
+
     class InputIterator
       include Enumerable
 
-      def initialize(input)
-        @input = if input.is_a?(Array)
+      def initialize(input, context)
+        @context = context
+        @input   = if input.is_a?(Array)
           input.flatten
         elsif input.is_a?(Hash)
           [input]
@@ -410,7 +853,9 @@ module Liquid
 
       def each
         @input.each do |e|
-          yield(e.respond_to?(:to_liquid) ? e.to_liquid : e)
+          e = e.respond_to?(:to_liquid) ? e.to_liquid : e
+          e.context = @context if e.respond_to?(:context=)
+          yield(e)
         end
       end
     end

lib/liquid/static_registers.rb

@@ -0,0 +1,48 @@
+# frozen_string_literal: true
+
+module Liquid
+  class StaticRegisters
+    attr_reader :static
+
+    def initialize(registers = {})
+      @static    = registers.is_a?(StaticRegisters) ? registers.static : registers
+      @registers = {}
+    end
+
+    def []=(key, value)
+      @registers[key] = value
+    end
+
+    def [](key)
+      if @registers.key?(key)
+        @registers[key]
+      else
+        @static[key]
+      end
+    end
+
+    def delete(key)
+      @registers.delete(key)
+    end
+
+    UNDEFINED = Object.new
+
+    def fetch(key, default = UNDEFINED, &block)
+      if @registers.key?(key)
+        @registers.fetch(key)
+      elsif default != UNDEFINED
+        if block_given?
+          @static.fetch(key, &block)
+        else
+          @static.fetch(key, default)
+        end
+      else
+        @static.fetch(key, &block)
+      end
+    end
+
+    def key?(key)
+      @registers.key?(key) || @static.key?(key)
+    end
+  end
+end

lib/liquid/strainer.rb

@@ -1,66 +0,0 @@
-require 'set'
-
-module Liquid
-  # Strainer is the parent class for the filters system.
-  # New filters are mixed into the strainer class which is then instantiated for each liquid template render run.
-  #
-  # The Strainer only allows method calls defined in filters given to it via Strainer.global_filter,
-  # Context#add_filters or Template.register_filter
-  class Strainer #:nodoc:
-    @@global_strainer = Class.new(Strainer) do
-      @filter_methods = Set.new
-    end
-    @@strainer_class_cache = Hash.new do |hash, filters|
-      hash[filters] = Class.new(@@global_strainer) do
-        @filter_methods = @@global_strainer.filter_methods.dup
-        filters.each { |f| add_filter(f) }
-      end
-    end
-
-    def initialize(context)
-      @context = context
-    end
-
-    class << self
-      attr_reader :filter_methods
-    end
-
-    def self.add_filter(filter)
-      raise ArgumentError, "Expected module but got: #{filter.class}" unless filter.is_a?(Module)
-      unless self.include?(filter)
-        invokable_non_public_methods = (filter.private_instance_methods + filter.protected_instance_methods).select { |m| invokable?(m) }
-        if invokable_non_public_methods.any?
-          raise MethodOverrideError, "Filter overrides registered public methods as non public: #{invokable_non_public_methods.join(', ')}"
-        else
-          send(:include, filter)
-          @filter_methods.merge(filter.public_instance_methods.map(&:to_s))
-        end
-      end
-    end
-
-    def self.global_filter(filter)
-      @@strainer_class_cache.clear
-      @@global_strainer.add_filter(filter)
-    end
-
-    def self.invokable?(method)
-      @filter_methods.include?(method.to_s)
-    end
-
-    def self.create(context, filters = [])
-      @@strainer_class_cache[filters].new(context)
-    end
-
-    def invoke(method, *args)
-      if self.class.invokable?(method)
-        send(method, *args)
-      elsif @context && @context.strict_filters
-        raise Liquid::UndefinedFilter, "undefined filter #{method}"
-      else
-        args.first
-      end
-    rescue ::ArgumentError => e
-      raise Liquid::ArgumentError, e.message, e.backtrace
-    end
-  end
-end

lib/liquid/strainer_factory.rb

@@ -0,0 +1,37 @@
+# frozen_string_literal: true
+
+module Liquid
+  # StrainerFactory is the factory for the filters system.
+  module StrainerFactory
+    extend self
+
+    def add_global_filter(filter)
+      strainer_class_cache.clear
+      GlobalCache.add_filter(filter)
+    end
+
+    def create(context, filters = [])
+      strainer_from_cache(filters).new(context)
+    end
+
+    GlobalCache = Class.new(StrainerTemplate)
+
+    private
+
+    def strainer_from_cache(filters)
+      if filters.empty?
+        GlobalCache
+      else
+        strainer_class_cache[filters] ||= begin
+          klass = Class.new(GlobalCache)
+          filters.each { |f| klass.add_filter(f) }
+          klass
+        end
+      end
+    end
+
+    def strainer_class_cache
+      @strainer_class_cache ||= {}
+    end
+  end
+end

lib/liquid/strainer_template.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require 'set'
+
+module Liquid
+  # StrainerTemplate is the computed class for the filters system.
+  # New filters are mixed into the strainer class which is then instantiated for each liquid template render run.
+  #
+  # The Strainer only allows method calls defined in filters given to it via StrainerFactory.add_global_filter,
+  # Context#add_filters or Template.register_filter
+  class StrainerTemplate
+    def initialize(context)
+      @context = context
+    end
+
+    class << self
+      def add_filter(filter)
+        return if include?(filter)
+
+        invokable_non_public_methods = (filter.private_instance_methods + filter.protected_instance_methods).select { |m| invokable?(m) }
+        if invokable_non_public_methods.any?
+          raise MethodOverrideError, "Filter overrides registered public methods as non public: #{invokable_non_public_methods.join(', ')}"
+        end
+
+        include(filter)
+
+        filter_methods.merge(filter.public_instance_methods.map(&:to_s))
+      end
+
+      def invokable?(method)
+        filter_methods.include?(method.to_s)
+      end
+
+      def inherited(subclass)
+        super
+        subclass.instance_variable_set(:@filter_methods, @filter_methods.dup)
+      end
+
+      private
+
+      def filter_methods
+        @filter_methods ||= Set.new
+      end
+    end
+
+    def invoke(method, *args)
+      if self.class.invokable?(method)
+        send(method, *args)
+      elsif @context.strict_filters
+        raise Liquid::UndefinedFilter, "undefined filter #{method}"
+      else
+        args.first
+      end
+    rescue ::ArgumentError => e
+      raise Liquid::ArgumentError, e.message, e.backtrace
+    end
+  end
+end

lib/liquid/tablerowloop_drop.rb

@@ -1,11 +1,13 @@
+# frozen_string_literal: true
+
 module Liquid
   class TablerowloopDrop < Drop
     def initialize(length, cols)
       @length = length
-      @row = 1
-      @col = 1
-      @cols = cols
-      @index = 0
+      @row    = 1
+      @col    = 1
+      @cols   = cols
+      @index  = 0
     end
 
     attr_reader :length, :col, :row

lib/liquid/tag.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Tag
     attr_reader :nodelist, :tag_name, :line_number, :parse_context
@@ -5,20 +7,26 @@ module Liquid
     include ParserSwitching
 
     class << self
-      def parse(tag_name, markup, tokenizer, options)
-        tag = new(tag_name, markup, options)
+      def parse(tag_name, markup, tokenizer, parse_context)
+        tag = new(tag_name, markup, parse_context)
         tag.parse(tokenizer)
         tag
       end
 
+      def disable_tags(*tag_names)
+        @disabled_tags ||= []
+        @disabled_tags.concat(tag_names)
+        prepend(Disabler)
+      end
+
       private :new
     end
 
     def initialize(tag_name, markup, parse_context)
-      @tag_name   = tag_name
-      @markup     = markup
+      @tag_name      = tag_name
+      @markup        = markup
       @parse_context = parse_context
-      @line_number = parse_context.line_number
+      @line_number   = parse_context.line_number
     end
 
     def parse(_tokens)
@@ -33,11 +41,25 @@ module Liquid
     end
 
     def render(_context)
-      ''.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
+
+    private
+
+    def parse_expression(markup)
+      parse_context.parse_expression(markup)
+    end
   end
 end

lib/liquid/tag/disableable.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module Liquid
+  class Tag
+    module Disableable
+      def render_to_output_buffer(context, output)
+        if context.tag_disabled?(tag_name)
+          output << disabled_error(context)
+          return
+        end
+        super
+      end
+
+      def disabled_error(context)
+        # raise then rescue the exception so that the Context#exception_renderer can re-raise it
+        raise DisabledError, "#{tag_name} #{parse_context[:locale].t('errors.disabled.tag')}"
+      rescue DisabledError => exc
+        context.handle_error(exc, line_number)
+      end
+    end
+  end
+end

lib/liquid/tag/disabler.rb

@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+module Liquid
+  class Tag
+    module Disabler
+      module ClassMethods
+        attr_reader :disabled_tags
+      end
+
+      def self.prepended(base)
+        base.extend(ClassMethods)
+      end
+
+      def render_to_output_buffer(context, output)
+        context.with_disabled_tags(self.class.disabled_tags) do
+          super
+        end
+      end
+    end
+  end
+end

lib/liquid/tags/assign.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Assign sets a variable in your template.
   #
@@ -10,21 +12,28 @@ module Liquid
   class Assign < Tag
     Syntax = /(#{VariableSignature}+)\s*=\s*(.*)\s*/om
 
-    def initialize(tag_name, markup, options)
+    # @api private
+    def self.raise_syntax_error(parse_context)
+      raise Liquid::SyntaxError, parse_context.locale.t('errors.syntax.assign')
+    end
+
+    attr_reader :to, :from
+
+    def initialize(tag_name, markup, parse_context)
       super
       if markup =~ Syntax
-        @to = $1
-        @from = Variable.new($2, options)
+        @to   = Regexp.last_match(1)
+        @from = Variable.new(Regexp.last_match(2), parse_context)
       else
-        raise SyntaxError.new options[:locale].t("errors.syntax.assign".freeze)
+        self.class.raise_syntax_error(parse_context)
       end
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       val = @from.render(context)
       context.scopes.last[@to] = val
-      context.resource_limits.assign_score += assign_score_of(val)
-      ''.freeze
+      context.resource_limits.increment_assign_score(assign_score_of(val))
+      output
     end
 
     def blank?
@@ -35,17 +44,30 @@ module Liquid
 
     def assign_score_of(val)
       if val.instance_of?(String)
-        val.length
-      elsif val.instance_of?(Array) || val.instance_of?(Hash)
+        val.bytesize
+      elsif val.instance_of?(Array)
         sum = 1
         # Uses #each to avoid extra allocations.
         val.each { |child| sum += assign_score_of(child) }
         sum
+      elsif val.instance_of?(Hash)
+        sum = 1
+        val.each do |key, entry_value|
+          sum += assign_score_of(key)
+          sum += assign_score_of(entry_value)
+        end
+        sum
       else
         1
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.from]
+      end
+    end
   end
 
-  Template.register_tag('assign'.freeze, Assign)
+  Template.register_tag('assign', Assign)
 end

lib/liquid/tags/break.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Break tag to be used to break out of a for loop.
   #
@@ -9,10 +11,13 @@ module Liquid
   #    {% endfor %}
   #
   class Break < Tag
-    def interrupt
-      BreakInterrupt.new
+    INTERRUPT = BreakInterrupt.new.freeze
+
+    def render_to_output_buffer(context, output)
+      context.push_interrupt(INTERRUPT)
+      output
     end
   end
 
-  Template.register_tag('break'.freeze, Break)
+  Template.register_tag('break', Break)
 end

lib/liquid/tags/capture.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Capture stores the result of a block into a variable without rendering it inplace.
   #
@@ -16,17 +18,18 @@ module Liquid
     def initialize(tag_name, markup, options)
       super
       if markup =~ Syntax
-        @to = $1
+        @to = Regexp.last_match(1)
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.capture"))
+        raise SyntaxError, options[:locale].t("errors.syntax.capture")
       end
     end
 
-    def render(context)
-      output = super
-      context.scopes.last[@to] = output
-      context.resource_limits.assign_score += output.length
-      ''.freeze
+    def render_to_output_buffer(context, output)
+      context.resource_limits.with_capture do
+        capture_output = render(context)
+        context.scopes.last[@to] = capture_output
+      end
+      output
     end
 
     def blank?
@@ -34,5 +37,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('capture'.freeze, Capture)
+  Template.register_tag('capture', Capture)
 end

lib/liquid/tags/case.rb

@@ -1,24 +1,55 @@
+# frozen_string_literal: true
+
 module Liquid
+  # @public_docs
+  # @title case
+  # @type tag
+  # @category controlflow
+  # @summary Creates a switch statement to execute a particular block of code when a variable has a specified value.
+  # @description
+  #   `case` initializes the switch statement, and `when` statements define the various conditions.
+  #
+  #   An optional `else` statement at the end of the case provides code to execute if none of the conditions are met.
+  # @syntax
+  #   {% case variable %}
+  #     {% when value1 %}
+  #       statement1
+  #     {% when value2 %}
+  #       statement2
+  #     {% when value3 %}
+  #       statement3
+  #     ...
+  #     {% else %}
+  #       else_statement
+  #   {% endcase %}
   class Case < Block
     Syntax     = /(#{QuotedFragment})/o
     WhenSyntax = /(#{QuotedFragment})(?:(?:\s+or\s+|\s*\,\s*)(#{QuotedFragment}.*))?/om
 
+    attr_reader :blocks, :left
+
     def initialize(tag_name, markup, options)
       super
       @blocks = []
 
       if markup =~ Syntax
-        @left = Expression.parse($1)
+        @left = parse_expression(Regexp.last_match(1))
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.case".freeze))
+        raise SyntaxError, options[:locale].t("errors.syntax.case")
       end
     end
 
     def parse(tokens)
-      body = BlockBody.new
-      while parse_body(body, tokens)
-        body = @blocks.last.attachment
+      body = case_body = new_body
+      body = @blocks.last.attachment while parse_body(body, tokens)
+      @blocks.reverse_each do |condition|
+        body = condition.attachment
+        unless body.frozen?
+          body.remove_blank_strings if blank?
+          body.freeze
+        end
       end
+      case_body.freeze
     end
 
     def nodelist
@@ -27,45 +58,50 @@ module Liquid
 
     def unknown_tag(tag, markup, tokens)
       case tag
-      when 'when'.freeze
+      when 'when'
         record_when_condition(markup)
-      when 'else'.freeze
+      when 'else'
         record_else_condition(markup)
       else
         super
       end
     end
 
-    def render(context)
-      context.stack do
-        execute_else_block = true
+    def render_to_output_buffer(context, output)
+      execute_else_block = true
 
-        output = ''
-        @blocks.each do |block|
-          if block.else?
-            return block.attachment.render(context) if execute_else_block
-          elsif block.evaluate(context)
-            execute_else_block = false
-            output << block.attachment.render(context)
-          end
+      @blocks.each do |block|
+        if block.else?
+          block.attachment.render_to_output_buffer(context, output) if execute_else_block
+          next
+        end
+
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
+          execute_else_block = false
+          block.attachment.render_to_output_buffer(context, output)
         end
-        output
       end
+
+      output
     end
 
     private
 
     def record_when_condition(markup)
-      body = BlockBody.new
+      body = new_body
 
       while markup
         unless markup =~ WhenSyntax
-          raise SyntaxError.new(options[:locale].t("errors.syntax.case_invalid_when".freeze))
+          raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_when")
         end
 
-        markup = $2
+        markup = Regexp.last_match(2)
 
-        block = Condition.new(@left, '=='.freeze, Expression.parse($1))
+        block = Condition.new(@left, '==', Condition.parse_expression(parse_context, Regexp.last_match(1)))
         block.attach(body)
         @blocks << block
       end
@@ -73,14 +109,20 @@ module Liquid
 
     def record_else_condition(markup)
       unless markup.strip.empty?
-        raise SyntaxError.new(options[:locale].t("errors.syntax.case_invalid_else".freeze))
+        raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_else")
       end
 
       block = ElseCondition.new
-      block.attach(BlockBody.new)
+      block.attach(new_body)
       @blocks << block
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.left] + @node.blocks
+      end
+    end
   end
 
-  Template.register_tag('case'.freeze, Case)
+  Template.register_tag('case', Case)
 end

lib/liquid/tags/comment.rb

@@ -1,7 +1,20 @@
+# frozen_string_literal: true
 module Liquid
+  # @public_docs
+  # @type tag
+  # @category theme
+  # @title comment
+  # @summary
+  #   Allows you to comment out parts of a Liquid file.
+  #   Any text within the opening and closing `comment` blocks won't be output,
+  #   and any Liquid code won't be executed.
+  # @syntax
+  #   {% comment %}
+  #     statement
+  #   {% endcomment %}
   class Comment < Block
-    def render(_context)
-      ''.freeze
+    def render_to_output_buffer(_context, output)
+      output
     end
 
     def unknown_tag(_tag, _markup, _tokens)
@@ -12,5 +25,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('comment'.freeze, Comment)
+  Template.register_tag('comment', Comment)
 end

lib/liquid/tags/continue.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Continue tag to be used to break out of a for loop.
   #
@@ -9,10 +11,13 @@ module Liquid
   #    {% endfor %}
   #
   class Continue < Tag
-    def interrupt
-      ContinueInterrupt.new
+    INTERRUPT = ContinueInterrupt.new.freeze
+
+    def render_to_output_buffer(context, output)
+      context.push_interrupt(INTERRUPT)
+      output
     end
   end
 
-  Template.register_tag('continue'.freeze, Continue)
+  Template.register_tag('continue', Continue)
 end

lib/liquid/tags/cycle.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Cycle is usually used within a loop to alternate between values, like colors or DOM classes.
   #
@@ -11,36 +13,60 @@ module Liquid
   #    <div class="red"> Item four </div>
   #    <div class="green"> Item five</div>
   #
+  # @public_docs
+  # @title cycle
+  # @type tag
+  # @category iteration
+  # @summary Loops through a group of strings and prints them in the order that they were passed as parameters.
+  # @description
+  #   Each time `cycle` is called, the next string that was passed as a parameter is printed.
+  #
+  #   `cycle` must be used within a `for` loop block.
+  # @syntax
+  #   {% for condition %}
+  #      {% cycle value1, value2 ... %}
+  #   {% endfor %}
   class Cycle < Tag
     SimpleSyntax = /\A#{QuotedFragment}+/o
     NamedSyntax  = /\A(#{QuotedFragment})\s*\:\s*(.*)/om
 
+    attr_reader :variables
+
     def initialize(tag_name, markup, options)
       super
       case markup
       when NamedSyntax
-        @variables = variables_from_string($2)
-        @name = Expression.parse($1)
+        @variables = variables_from_string(Regexp.last_match(2))
+        @name      = parse_expression(Regexp.last_match(1))
       when SimpleSyntax
         @variables = variables_from_string(markup)
-        @name = @variables.to_s
+        @name      = @variables.to_s
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.cycle".freeze))
+        raise SyntaxError, options[:locale].t("errors.syntax.cycle")
       end
     end
 
-    def render(context)
-      context.registers[:cycle] ||= Hash.new(0)
+    def render_to_output_buffer(context, output)
+      context.registers[:cycle] ||= {}
 
-      context.stack do
-        key = context.evaluate(@name)
-        iteration = context.registers[:cycle][key]
-        result = context.evaluate(@variables[iteration])
-        iteration += 1
-        iteration  = 0 if iteration >= @variables.size
-        context.registers[:cycle][key] = iteration
-        result
+      key       = context.evaluate(@name)
+      iteration = context.registers[:cycle][key].to_i
+
+      val = context.evaluate(@variables[iteration])
+
+      if val.is_a?(Array)
+        val = val.join
+      elsif !val.is_a?(String)
+        val = val.to_s
       end
+
+      output << val
+
+      iteration += 1
+      iteration = 0 if iteration >= @variables.size
+
+      context.registers[:cycle][key] = iteration
+      output
     end
 
     private
@@ -48,9 +74,15 @@ module Liquid
     def variables_from_string(markup)
       markup.split(',').collect do |var|
         var =~ /\s*(#{QuotedFragment})\s*/o
-        $1 ? Expression.parse($1) : nil
+        Regexp.last_match(1) ? parse_expression(Regexp.last_match(1)) : nil
       end.compact
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        Array(@node.variables)
+      end
+    end
   end
 
   Template.register_tag('cycle', Cycle)

lib/liquid/tags/decrement.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # decrement is used in a place where one needs to insert a counter
   #     into a template, and needs the counter to survive across
@@ -23,13 +25,14 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
       value -= 1
       context.environments.first[@variable] = value
-      value.to_s
+      output << value.to_s
+      output
     end
   end
 
-  Template.register_tag('decrement'.freeze, Decrement)
+  Template.register_tag('decrement', Decrement)
 end

lib/liquid/tags/echo.rb

@@ -0,0 +1,34 @@
+# frozen_string_literal: true
+
+module Liquid
+  # @public_docs
+  # @type tag
+  # @category theme
+  # @title echo
+  # @summary
+  #   Outputs an expression, or Liquid object, in the rendered HTML.
+  #   Works the same as wrapping an expression in double curly brace delimiters `{{ }}`.
+  #   Works inside the [`liquid`](/api/liquid/tags/theme-tags#liquid) tag and supports [filters](/api/liquid/filters).
+  # @syntax
+  #   {% echo 'string' %}
+  class Echo < Tag
+    attr_reader :variable
+
+    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
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.variable]
+      end
+    end
+  end
+
+  Template.register_tag('echo', Echo)
+end

lib/liquid/tags/for.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # "For" iterates over an array or collection.
   # Several useful variables are available to you within the loop.
@@ -43,20 +45,43 @@ module Liquid
   # forloop.last:: Returns true if the item is the last item.
   # forloop.parentloop:: Provides access to the parent loop, if present.
   #
+  # @public_docs
+  # @title for
+  # @type tag
+  # @category iteration
+  # @summary Repeatedly executes a block of code.
+  # @description
+  #    You can output a maximum of 50 results per page with `for` loops. In cases where there are more than 50 results,
+  #    use the [`paginate`](/api/liquid/tags/theme-tags#paginate) tag to split them across multiple pages.
+  #
+  #    For a full list of attributes available within a `for` loop, refer to the [`forloop`](/api/liquid/objects/for-loops) object.
+  # @syntax
+  #   {% for variable in iterable parameters %}
+  # @optional_param limit [number] Exit the `for` loop at the specified index.
+  # @optional_param offset [number] Start the `for` loop at the specified index.
   class For < Block
     Syntax = /\A(#{VariableSegment}+)\s+in\s+(#{QuotedFragment}+)\s*(reversed)?/o
 
+    attr_reader :collection_name, :variable_name, :limit, :from
+
     def initialize(tag_name, markup, options)
       super
       @from = @limit = nil
       parse_with_selected_parser(markup)
-      @for_block = BlockBody.new
+      @for_block = new_body
       @else_block = nil
     end
 
     def parse(tokens)
-      return unless parse_body(@for_block, tokens)
-      parse_body(@else_block, tokens)
+      if parse_body(@for_block, tokens)
+        parse_body(@else_block, tokens)
+      end
+      if blank?
+        @else_block&.remove_blank_strings
+        @for_block.remove_blank_strings
+      end
+      @else_block&.freeze
+      @for_block.freeze
     end
 
     def nodelist
@@ -64,49 +89,53 @@ module Liquid
     end
 
     def unknown_tag(tag, markup, tokens)
-      return super unless tag == 'else'.freeze
-      @else_block = BlockBody.new
+      return super unless tag == 'else'
+      @else_block = new_body
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       segment = collection_segment(context)
 
       if segment.empty?
-        render_else(context)
+        render_else(context, output)
       else
-        render_segment(context, segment)
+        render_segment(context, output, segment)
       end
+
+      output
     end
 
     protected
 
     def lax_parse(markup)
       if markup =~ Syntax
-        @variable_name = $1
-        collection_name = $2
-        @reversed = !!$3
-        @name = "#{@variable_name}-#{collection_name}"
-        @collection_name = Expression.parse(collection_name)
+        @variable_name   = Regexp.last_match(1)
+        collection_name  = Regexp.last_match(2)
+        @reversed        = !!Regexp.last_match(3)
+        @name            = "#{@variable_name}-#{collection_name}"
+        @collection_name = parse_expression(collection_name)
         markup.scan(TagAttributes) do |key, value|
           set_attribute(key, value)
         end
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.for".freeze))
+        raise SyntaxError, options[:locale].t("errors.syntax.for")
       end
     end
 
     def strict_parse(markup)
       p = Parser.new(markup)
       @variable_name = p.consume(:id)
-      raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_in".freeze)) unless p.id?('in'.freeze)
-      collection_name = p.expression
-      @name = "#{@variable_name}-#{collection_name}"
-      @collection_name = Expression.parse(collection_name)
-      @reversed = p.id?('reversed'.freeze)
+      raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_in") unless p.id?('in')
+
+      collection_name  = p.expression
+      @collection_name = parse_expression(collection_name)
+
+      @name     = "#{@variable_name}-#{collection_name}"
+      @reversed = p.id?('reversed')
 
       while p.look(:id) && p.look(:colon, 1)
-        unless attribute = p.id?('limit'.freeze) || p.id?('offset'.freeze)
-          raise SyntaxError.new(options[:locale].t("errors.syntax.for_invalid_attribute".freeze))
+        unless (attribute = p.id?('limit') || p.id?('offset'))
+          raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_attribute")
         end
         p.consume
         set_attribute(attribute, p.expression)
@@ -117,19 +146,28 @@ module Liquid
     private
 
     def collection_segment(context)
-      offsets = context.registers[:for] ||= Hash.new(0)
+      offsets = context.registers[:for] ||= {}
 
       from = if @from == :continue
         offsets[@name].to_i
       else
-        context.evaluate(@from).to_i
+        from_value = context.evaluate(@from)
+        if from_value.nil?
+          0
+        else
+          Utils.to_integer(from_value)
+        end
       end
 
       collection = context.evaluate(@collection_name)
       collection = collection.to_a if collection.is_a?(Range)
 
-      limit = context.evaluate(@limit)
-      to = limit ? limit.to_i + from : nil
+      limit_value = context.evaluate(@limit)
+      to = if limit_value.nil?
+        nil
+      else
+        Utils.to_integer(limit_value) + from
+      end
 
       segment = Utils.slice_collection(collection, from, to)
       segment.reverse! if @reversed
@@ -139,11 +177,9 @@ module Liquid
       segment
     end
 
-    def render_segment(context, segment)
+    def render_segment(context, output, segment)
       for_stack = context.registers[:for_stack] ||= []
-      length = segment.length
-
-      result = ''
+      length    = segment.length
 
       context.stack do
         loop_vars = Liquid::ForloopDrop.new(@name, length, for_stack[-1])
@@ -151,45 +187,55 @@ module Liquid
         for_stack.push(loop_vars)
 
         begin
-          context['forloop'.freeze] = loop_vars
+          context['forloop'] = loop_vars
 
-          segment.each_with_index do |item, index|
+          segment.each do |item|
             context[@variable_name] = item
-            result << @for_block.render(context)
+            @for_block.render_to_output_buffer(context, output)
             loop_vars.send(:increment!)
 
             # Handle any interrupts if they exist.
-            if context.interrupt?
-              interrupt = context.pop_interrupt
-              break if interrupt.is_a? BreakInterrupt
-              next if interrupt.is_a? ContinueInterrupt
-            end
+            next unless context.interrupt?
+            interrupt = context.pop_interrupt
+            break if interrupt.is_a?(BreakInterrupt)
+            next if interrupt.is_a?(ContinueInterrupt)
           end
         ensure
           for_stack.pop
         end
       end
 
-      result
+      output
     end
 
     def set_attribute(key, expr)
       case key
-      when 'offset'.freeze
-        @from = if expr == 'continue'.freeze
+      when 'offset'
+        @from = if expr == 'continue'
+          Usage.increment('for_offset_continue')
           :continue
         else
-          Expression.parse(expr)
+          parse_expression(expr)
         end
-      when 'limit'.freeze
-        @limit = Expression.parse(expr)
+      when 'limit'
+        @limit = parse_expression(expr)
       end
     end
 
-    def render_else(context)
-      @else_block ? @else_block.render(context) : ''.freeze
+    def render_else(context, output)
+      if @else_block
+        @else_block.render_to_output_buffer(context, output)
+      else
+        output
+      end
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        (super + [@node.limit, @node.from, @node.collection_name]).compact
+      end
     end
   end
 
-  Template.register_tag('for'.freeze, For)
+  Template.register_tag('for', For)
 end

lib/liquid/tags/if.rb

@@ -1,79 +1,98 @@
+# frozen_string_literal: true
+
 module Liquid
   # If is the conditional block
   #
-  #   {% if user.admin %}
-  #     Admin user!
-  #   {% else %}
-  #     Not admin user
+  # @public_docs
+  # @title if
+  # @type tag
+  # @category controlflow
+  # @summary Executes a block of code only if a certain condition is met (if the result is `truthy`).
+  # @syntax
+  #   {% if variable operator value %}
+  #     statement
   #   {% endif %}
-  #
-  #    There are {% if count < 5 %} less {% else %} more {% endif %} items than you need.
-  #
   class If < Block
-    Syntax = /(#{QuotedFragment})\s*([=!<>a-z_]+)?\s*(#{QuotedFragment})?/o
+    Syntax                  = /(#{QuotedFragment})\s*([=!<>a-z_]+)?\s*(#{QuotedFragment})?/o
     ExpressionsAndOperators = /(?:\b(?:\s?and\s?|\s?or\s?)\b|(?:\s*(?!\b(?:\s?and\s?|\s?or\s?)\b)(?:#{QuotedFragment}|\S+)\s*)+)/o
-    BOOLEAN_OPERATORS = %w(and or)
+    BOOLEAN_OPERATORS       = %w(and or).freeze
+
+    attr_reader :blocks
 
     def initialize(tag_name, markup, options)
       super
       @blocks = []
-      push_block('if'.freeze, markup)
-    end
-
-    def parse(tokens)
-      while parse_body(@blocks.last.attachment, tokens)
-      end
+      push_block('if', markup)
     end
 
     def nodelist
       @blocks.map(&:attachment)
     end
 
+    def parse(tokens)
+      while parse_body(@blocks.last.attachment, tokens)
+      end
+      @blocks.reverse_each do |block|
+        block.attachment.remove_blank_strings if blank?
+        block.attachment.freeze
+      end
+    end
+
+    ELSE_TAG_NAMES = ['elsif', 'else'].freeze
+    private_constant :ELSE_TAG_NAMES
+
     def unknown_tag(tag, markup, tokens)
-      if ['elsif'.freeze, 'else'.freeze].include?(tag)
+      if ELSE_TAG_NAMES.include?(tag)
         push_block(tag, markup)
       else
         super
       end
     end
 
-    def render(context)
-      context.stack do
-        @blocks.each do |block|
-          if block.evaluate(context)
-            return block.attachment.render(context)
-          end
+    def render_to_output_buffer(context, output)
+      @blocks.each do |block|
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
+          return block.attachment.render_to_output_buffer(context, output)
         end
-        ''.freeze
       end
+
+      output
     end
 
     private
 
     def push_block(tag, markup)
-      block = if tag == 'else'.freeze
+      block = if tag == 'else'
         ElseCondition.new
       else
         parse_with_selected_parser(markup)
       end
 
       @blocks.push(block)
-      block.attach(BlockBody.new)
+      block.attach(new_body)
+    end
+
+    def parse_expression(markup)
+      Condition.parse_expression(parse_context, markup)
     end
 
     def lax_parse(markup)
       expressions = markup.scan(ExpressionsAndOperators)
-      raise(SyntaxError.new(options[:locale].t("errors.syntax.if".freeze))) unless expressions.pop =~ Syntax
+      raise SyntaxError, options[:locale].t("errors.syntax.if") unless expressions.pop =~ Syntax
 
-      condition = Condition.new(Expression.parse($1), $2, Expression.parse($3))
+      condition = Condition.new(parse_expression(Regexp.last_match(1)), Regexp.last_match(2), parse_expression(Regexp.last_match(3)))
 
       until expressions.empty?
         operator = expressions.pop.to_s.strip
 
-        raise(SyntaxError.new(options[:locale].t("errors.syntax.if".freeze))) unless expressions.pop.to_s =~ Syntax
+        raise SyntaxError, options[:locale].t("errors.syntax.if") unless expressions.pop.to_s =~ Syntax
 
-        new_condition = Condition.new(Expression.parse($1), $2, Expression.parse($3))
-        raise(SyntaxError.new(options[:locale].t("errors.syntax.if".freeze))) unless BOOLEAN_OPERATORS.include?(operator)
+        new_condition = Condition.new(parse_expression(Regexp.last_match(1)), Regexp.last_match(2), parse_expression(Regexp.last_match(3)))
+        raise SyntaxError, options[:locale].t("errors.syntax.if") unless BOOLEAN_OPERATORS.include?(operator)
         new_condition.send(operator, condition)
         condition = new_condition
       end
@@ -83,29 +102,38 @@ module Liquid
 
     def strict_parse(markup)
       p = Parser.new(markup)
-      condition = parse_binary_comparison(p)
+      condition = parse_binary_comparisons(p)
       p.consume(:end_of_string)
       condition
     end
 
-    def parse_binary_comparison(p)
+    def parse_binary_comparisons(p)
       condition = parse_comparison(p)
-      if op = (p.id?('and'.freeze) || p.id?('or'.freeze))
-        condition.send(op, parse_binary_comparison(p))
+      first_condition = condition
+      while (op = (p.id?('and') || p.id?('or')))
+        child_condition = parse_comparison(p)
+        condition.send(op, child_condition)
+        condition = child_condition
       end
-      condition
+      first_condition
     end
 
     def parse_comparison(p)
-      a = Expression.parse(p.expression)
-      if op = p.consume?(:comparison)
-        b = Expression.parse(p.expression)
+      a = parse_expression(p.expression)
+      if (op = p.consume?(:comparison))
+        b = parse_expression(p.expression)
         Condition.new(a, op, b)
       else
         Condition.new(a)
       end
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        @node.blocks
+      end
+    end
   end
 
-  Template.register_tag('if'.freeze, If)
+  Template.register_tag('if', If)
 end

lib/liquid/tags/ifchanged.rb

@@ -1,18 +1,19 @@
+# frozen_string_literal: true
+
 module Liquid
   class Ifchanged < Block
-    def render(context)
-      context.stack do
-        output = super
+    def render_to_output_buffer(context, output)
+      block_output = +''
+      super(context, block_output)
 
-        if output != context.registers[:ifchanged]
-          context.registers[:ifchanged] = output
-          output
-        else
-          ''.freeze
-        end
+      if block_output != context.registers[:ifchanged]
+        context.registers[:ifchanged] = block_output
+        output << block_output
       end
+
+      output
     end
   end
 
-  Template.register_tag('ifchanged'.freeze, Ifchanged)
+  Template.register_tag('ifchanged', Ifchanged)
 end

lib/liquid/tags/include.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Include allows templates to relate with other templates
   #
@@ -14,38 +16,49 @@ module Liquid
   #   {% include 'product' for products %}
   #
   class Include < Tag
-    Syntax = /(#{QuotedFragment}+)(\s+(?:with|for)\s+(#{QuotedFragment}+))?/o
+    prepend Tag::Disableable
+
+    SYNTAX = /(#{QuotedFragment}+)(\s+(?:with|for)\s+(#{QuotedFragment}+))?(\s+(?:as)\s+(#{VariableSegment}+))?/o
+    Syntax = SYNTAX
+
+    attr_reader :template_name_expr, :variable_name_expr, :attributes
 
     def initialize(tag_name, markup, options)
       super
 
-      if markup =~ Syntax
+      if markup =~ SYNTAX
 
-        template_name = $1
-        variable_name = $3
+        template_name = Regexp.last_match(1)
+        variable_name = Regexp.last_match(3)
 
-        @variable_name_expr = variable_name ? Expression.parse(variable_name) : nil
-        @template_name_expr = Expression.parse(template_name)
-        @attributes = {}
+        @alias_name         = Regexp.last_match(5)
+        @variable_name_expr = variable_name ? parse_expression(variable_name) : nil
+        @template_name_expr = parse_expression(template_name)
+        @attributes         = {}
 
         markup.scan(TagAttributes) do |key, value|
-          @attributes[key] = Expression.parse(value)
+          @attributes[key] = parse_expression(value)
         end
 
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.include".freeze))
+        raise SyntaxError, options[:locale].t("errors.syntax.include")
       end
     end
 
     def parse(_tokens)
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       template_name = context.evaluate(@template_name_expr)
-      raise ArgumentError.new(options[:locale].t("errors.argument.include")) unless template_name
+      raise ArgumentError, options[:locale].t("errors.argument.include") unless template_name
 
-      partial = load_cached_partial(template_name, context)
-      context_variable_name = template_name.split('/'.freeze).last
+      partial = PartialCache.load(
+        template_name,
+        context: context,
+        parse_context: parse_context
+      )
+
+      context_variable_name = @alias_name || template_name.split('/').last
 
       variable = if @variable_name_expr
         context.evaluate(@variable_name_expr)
@@ -54,60 +67,45 @@ module Liquid
       end
 
       old_template_name = context.template_name
-      old_partial = context.partial
+      old_partial       = context.partial
       begin
         context.template_name = template_name
-        context.partial = true
+        context.partial       = true
         context.stack do
           @attributes.each do |key, value|
             context[key] = context.evaluate(value)
           end
 
           if variable.is_a?(Array)
-            variable.collect do |var|
+            variable.each do |var|
               context[context_variable_name] = var
-              partial.render(context)
+              partial.render_to_output_buffer(context, output)
             end
           else
             context[context_variable_name] = variable
-            partial.render(context)
+            partial.render_to_output_buffer(context, output)
           end
         end
       ensure
         context.template_name = old_template_name
-        context.partial = old_partial
+        context.partial       = old_partial
       end
-    end
 
-    private
+      output
+    end
 
     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
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.template_name_expr,
+          @node.variable_name_expr,
+        ] + @node.attributes.values
       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
   end
 
-  Template.register_tag('include'.freeze, Include)
+  Template.register_tag('include', Include)
 end

lib/liquid/tags/increment.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # increment is used in a place where one needs to insert a counter
   #     into a template, and needs the counter to survive across
@@ -20,12 +22,14 @@ module Liquid
       @variable = markup.strip
     end
 
-    def render(context)
+    def render_to_output_buffer(context, output)
       value = context.environments.first[@variable] ||= 0
       context.environments.first[@variable] = value + 1
-      value.to_s
+
+      output << value.to_s
+      output
     end
   end
 
-  Template.register_tag('increment'.freeze, Increment)
+  Template.register_tag('increment', Increment)
 end

lib/liquid/tags/raw.rb

@@ -1,4 +1,16 @@
+# frozen_string_literal: true
+
 module Liquid
+  # @public_docs
+  # @type tag
+  # @category theme
+  # @title raw
+  # @summary
+  #   Allows you to output Liquid code on a page without it being parsed.
+  # @syntax
+  #   {% raw %}
+  #     liquid
+  #   {% endraw %}
   class Raw < Block
     Syntax = /\A\s*\z/
     FullTokenPossiblyInvalid = /\A(.*)#{TagStart}\s*(\w+)\s*(.*)?#{TagEnd}\z/om
@@ -10,20 +22,21 @@ module Liquid
     end
 
     def parse(tokens)
-      @body = ''
-      while token = tokens.shift
-        if token =~ FullTokenPossiblyInvalid
-          @body << $1 if $1 != "".freeze
-          return if block_delimiter == $2
+      @body = +''
+      while (token = tokens.shift)
+        if token =~ FullTokenPossiblyInvalid && block_delimiter == Regexp.last_match(2)
+          @body << Regexp.last_match(1) if Regexp.last_match(1) != ""
+          return
         end
         @body << token unless token.empty?
       end
 
-      raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name))
+      raise_tag_never_closed(block_name)
     end
 
-    def render(_context)
-      @body
+    def render_to_output_buffer(_context, output)
+      output << @body
+      output
     end
 
     def nodelist
@@ -37,11 +50,11 @@ module Liquid
     protected
 
     def ensure_valid_markup(tag_name, markup, parse_context)
-      unless markup =~ Syntax
-        raise SyntaxError.new(parse_context.locale.t("errors.syntax.tag_unexpected_args".freeze, tag: tag_name))
+      unless Syntax.match?(markup)
+        raise SyntaxError, parse_context.locale.t("errors.syntax.tag_unexpected_args", tag: tag_name)
       end
     end
   end
 
-  Template.register_tag('raw'.freeze, Raw)
+  Template.register_tag('raw', Raw)
 end

lib/liquid/tags/render.rb

@@ -0,0 +1,106 @@
+# frozen_string_literal: true
+
+module Liquid
+  # @public_docs
+  # @type tag
+  # @category theme
+  # @title render
+  # @summary
+  #   Renders a snippet from the **snippets** folder of a theme, or [code for an app block](/themes/architecture/sections/section-schema#render-app-blocks).
+  #  You don't need to write the file's `.liquid` extension.
+  # @description
+  #    When a snippet is rendered, the code inside it doesn't automatically have access to the variables assigned
+  #    using [variable tags](/api/liquid/tags/variable-tags) within the snippet's parent template.
+  #    Similarly, variables assigned within the snippet can't be accessed by the code outside of the snippet.
+  #    This encapsulation increases performance and helps make theme code easier to understand and maintain.
+  #
+  #    You can't use an [`include`](/api/liquid/tags/theme-tags#include) tag inside of a snippet rendered using the `render` tag.
+  #
+  #    > Tip:
+  #    > This tag replaces the deprecated [`include`](/api/liquid/tags/theme-tags#include) tag.
+  # @syntax
+  #   {% render reference %}
+  # @optional_param with [string] Pass an object to use in the snippet. Use with the `as` parameter.
+  # @optional_param for [string] Render the snippet once for each value of an enumerable object. Use with the `as` parameter. When using the `for` parameter, the [`forloop`](/api/liquid/objects/for-loops) object is accessible within the snippet.
+  # @optional_param as [string] The variable that the object referenced by a `with` or `for` parameter represents within the snippet.
+  class Render < Tag
+    FOR = 'for'
+    SYNTAX = /(#{QuotedString}+)(\s+(with|#{FOR})\s+(#{QuotedFragment}+))?(\s+(?:as)\s+(#{VariableSegment}+))?/o
+
+    disable_tags "include"
+
+    attr_reader :template_name_expr, :attributes
+
+    def initialize(tag_name, markup, options)
+      super
+
+      raise SyntaxError, options[:locale].t("errors.syntax.render") unless markup =~ SYNTAX
+
+      template_name = Regexp.last_match(1)
+      with_or_for = Regexp.last_match(3)
+      variable_name = Regexp.last_match(4)
+
+      @alias_name = Regexp.last_match(6)
+      @variable_name_expr = variable_name ? parse_expression(variable_name) : nil
+      @template_name_expr = parse_expression(template_name)
+      @for = (with_or_for == FOR)
+
+      @attributes = {}
+      markup.scan(TagAttributes) do |key, value|
+        @attributes[key] = parse_expression(value)
+      end
+    end
+
+    def render_to_output_buffer(context, output)
+      render_tag(context, output)
+    end
+
+    def render_tag(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, options[:locale].t("errors.argument.include") unless template_name
+
+      partial = PartialCache.load(
+        template_name,
+        context: context,
+        parse_context: parse_context
+      )
+
+      context_variable_name = @alias_name || template_name.split('/').last
+
+      render_partial_func = ->(var, forloop) {
+        inner_context               = context.new_isolated_subcontext
+        inner_context.template_name = template_name
+        inner_context.partial       = true
+        inner_context['forloop']    = forloop if forloop
+
+        @attributes.each do |key, value|
+          inner_context[key] = context.evaluate(value)
+        end
+        inner_context[context_variable_name] = var unless var.nil?
+        partial.render_to_output_buffer(inner_context, output)
+        forloop&.send(:increment!)
+      }
+
+      variable = @variable_name_expr ? context.evaluate(@variable_name_expr) : nil
+      if @for && variable.respond_to?(:each) && variable.respond_to?(:count)
+        forloop = Liquid::ForloopDrop.new(template_name, variable.count, nil)
+        variable.each { |var| render_partial_func.call(var, forloop) }
+      else
+        render_partial_func.call(variable, nil)
+      end
+
+      output
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [
+          @node.template_name_expr,
+        ] + @node.attributes.values
+      end
+    end
+  end
+
+  Template.register_tag('render', Render)
+end

lib/liquid/tags/table_row.rb

@@ -1,54 +1,83 @@
+# frozen_string_literal: true
+
 module Liquid
+  # @public_docs
+  # @title tablerow
+  # @type tag
+  # @category iteration
+  # @summary Generates rows for an HTML table.
+  # @description
+  #   Must be wrapped in opening `<table>` and closing `</table>` HTML tags.
+  #   For a full list of attributes available within a `tablerow` loop, refer to the [`tablerow`](/api/liquid/objects/tablerow) object.
+  # @syntax
+  #   <table>
+  #     {% tablerow variable in interable parameters %}
+  #       content
+  #     {% endtablerow %}
+  #   </table>
+  # @optional_param cols [number] The number of columns the table should have.
+  # @optional_param limit [number] Exit the `tablerow` loop at the specified index.
+  # @optional_param offset [number] Start the `tablerow` loop at the specified index.
   class TableRow < Block
     Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)/o
 
+    attr_reader :variable_name, :collection_name, :attributes
+
     def initialize(tag_name, markup, options)
       super
       if markup =~ Syntax
-        @variable_name = $1
-        @collection_name = Expression.parse($2)
-        @attributes = {}
+        @variable_name   = Regexp.last_match(1)
+        @collection_name = parse_expression(Regexp.last_match(2))
+        @attributes      = {}
         markup.scan(TagAttributes) do |key, value|
-          @attributes[key] = Expression.parse(value)
+          @attributes[key] = parse_expression(value)
         end
       else
-        raise SyntaxError.new(options[:locale].t("errors.syntax.table_row".freeze))
+        raise SyntaxError, options[:locale].t("errors.syntax.table_row")
       end
     end
 
-    def render(context)
-      collection = context.evaluate(@collection_name) or return ''.freeze
+    def render_to_output_buffer(context, output)
+      (collection = context.evaluate(@collection_name)) || (return '')
 
-      from = @attributes.key?('offset'.freeze) ? context.evaluate(@attributes['offset'.freeze]).to_i : 0
-      to = @attributes.key?('limit'.freeze) ? from + context.evaluate(@attributes['limit'.freeze]).to_i : nil
+      from = @attributes.key?('offset') ? context.evaluate(@attributes['offset']).to_i : 0
+      to   = @attributes.key?('limit')  ? from + context.evaluate(@attributes['limit']).to_i : nil
 
       collection = Utils.slice_collection(collection, from, to)
+      length     = collection.length
 
-      length = collection.length
+      cols = context.evaluate(@attributes['cols']).to_i
 
-      cols = context.evaluate(@attributes['cols'.freeze]).to_i
-
-      result = "<tr class=\"row1\">\n"
+      output << "<tr class=\"row1\">\n"
       context.stack do
         tablerowloop = Liquid::TablerowloopDrop.new(length, cols)
-        context['tablerowloop'.freeze] = tablerowloop
+        context['tablerowloop'] = tablerowloop
 
-        collection.each_with_index do |item, index|
+        collection.each do |item|
           context[@variable_name] = item
 
-          result << "<td class=\"col#{tablerowloop.col}\">" << super << '</td>'
+          output << "<td class=\"col#{tablerowloop.col}\">"
+          super
+          output << '</td>'
 
           if tablerowloop.col_last && !tablerowloop.last
-            result << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
+            output << "</tr>\n<tr class=\"row#{tablerowloop.row + 1}\">"
           end
 
           tablerowloop.send(:increment!)
         end
       end
-      result << "</tr>\n"
-      result
+
+      output << "</tr>\n"
+      output
+    end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        super + @node.attributes.values + [@node.collection_name]
+      end
     end
   end
 
-  Template.register_tag('tablerow'.freeze, TableRow)
+  Template.register_tag('tablerow', TableRow)
 end

lib/liquid/tags/unless.rb

@@ -1,30 +1,43 @@
+# frozen_string_literal: true
+
 require_relative 'if'
 
 module Liquid
-  # Unless is a conditional just like 'if' but works on the inverse logic.
-  #
-  #   {% unless x < 0 %} x is greater than zero {% endunless %}
-  #
+  # @public_docs
+  # @title unless
+  # @type tag
+  # @category controlflow
+  # @summary Executes a block of code only if a certain condition is not met (if the result is `falsy`).
+  # @syntax
+  #   {% unless variable operator value %}
+  #     statement
+  #   {% endunless %}
   class Unless < If
-    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(context)
-        end
+    def render_to_output_buffer(context, output)
+      # First condition is interpreted backwards ( if not )
+      first_block = @blocks.first
+      result = Liquid::Utils.to_liquid_value(
+        first_block.evaluate(context)
+      )
 
-        # After the first condition unless works just like if
-        @blocks[1..-1].each do |block|
-          if block.evaluate(context)
-            return block.attachment.render(context)
-          end
-        end
-
-        ''.freeze
+      unless result
+        return first_block.attachment.render_to_output_buffer(context, output)
       end
+
+      # After the first condition unless works just like if
+      @blocks[1..-1].each do |block|
+        result = Liquid::Utils.to_liquid_value(
+          block.evaluate(context)
+        )
+
+        if result
+          return block.attachment.render_to_output_buffer(context, output)
+        end
+      end
+
+      output
     end
   end
 
-  Template.register_tag('unless'.freeze, Unless)
+  Template.register_tag('unless', Unless)
 end

lib/liquid/template.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Templates are central to liquid.
   # Interpretating templates is a two step process. First you compile the
@@ -16,13 +18,11 @@ module Liquid
     attr_accessor :root
     attr_reader :resource_limits, :warnings
 
-    @@file_system = BlankFileSystem.new
-
     class TagRegistry
       include Enumerable
 
       def initialize
-        @tags = {}
+        @tags  = {}
         @cache = {}
       end
 
@@ -50,7 +50,7 @@ module Liquid
       private
 
       def lookup_class(name)
-        name.split("::").reject(&:empty?).reduce(Object) { |scope, const| scope.const_get(const) }
+        Object.const_get(name)
       end
     end
 
@@ -61,76 +61,54 @@ module Liquid
       # :lax acts like liquid 2.5 and silently ignores malformed tags in most cases.
       # :warn is the default and will give deprecation warnings when invalid syntax is used.
       # :strict will enforce correct syntax.
-      attr_writer :error_mode
-
-      # Sets how strict the taint checker should be.
-      # :lax is the default, and ignores the taint flag completely
-      # :warn adds a warning, but does not interrupt the rendering
-      # :error raises an error when tainted output is used
-      attr_writer :taint_mode
+      attr_accessor :error_mode
+      Template.error_mode = :lax
 
       attr_accessor :default_exception_renderer
       Template.default_exception_renderer = lambda do |exception|
         exception
       end
 
-      def file_system
-        @@file_system
-      end
+      attr_accessor :file_system
+      Template.file_system = BlankFileSystem.new
 
-      def file_system=(obj)
-        @@file_system = obj
-      end
+      attr_accessor :tags
+      Template.tags = TagRegistry.new
+      private :tags=
 
       def register_tag(name, klass)
         tags[name.to_s] = klass
       end
 
-      def tags
-        @tags ||= TagRegistry.new
-      end
-
-      def error_mode
-        @error_mode ||= :lax
-      end
-
-      def taint_mode
-        @taint_mode ||= :lax
-      end
-
       # Pass a module with filter methods which should be available
       # to all liquid views. Good for registering the standard library
       def register_filter(mod)
-        Strainer.global_filter(mod)
+        StrainerFactory.add_global_filter(mod)
       end
 
-      def default_resource_limits
-        @default_resource_limits ||= {}
-      end
+      attr_accessor :default_resource_limits
+      Template.default_resource_limits = {}
+      private :default_resource_limits=
 
       # creates a new <tt>Template</tt> object from liquid source code
       # To enable profiling, pass in <tt>profile: true</tt> as an option.
       # See Liquid::Profiler for more information
       def parse(source, options = {})
-        template = Template.new
-        template.parse(source, options)
+        new.parse(source, options)
       end
     end
 
     def initialize
-      @rethrow_errors = false
-      @resource_limits = ResourceLimits.new(self.class.default_resource_limits)
+      @rethrow_errors  = false
+      @resource_limits = ResourceLimits.new(Template.default_resource_limits)
     end
 
     # Parse source code.
     # Returns self for easy chaining
     def parse(source, options = {})
-      @options = options
-      @profiling = options[:profile]
-      @line_numbers = options[:line_numbers] || @profiling
-      parse_context = options.is_a?(ParseContext) ? options : ParseContext.new(options)
-      @root = Document.parse(tokenize(source), parse_context)
-      @warnings = parse_context.warnings
+      parse_context = configure_options(options)
+      tokenizer     = parse_context.new_tokenizer(source, start_line_number: @line_numbers && 1)
+      @root         = Document.parse(tokenizer, parse_context)
       self
     end
 
@@ -165,19 +143,19 @@ module Liquid
     #    filters and tags and might be useful to integrate liquid more with its host application
     #
     def render(*args)
-      return ''.freeze if @root.nil?
+      return '' if @root.nil?
 
       context = case args.first
       when Liquid::Context
         c = args.shift
 
         if @rethrow_errors
-          c.exception_renderer = ->(e) { raise }
+          c.exception_renderer = Liquid::RAISE_EXCEPTION_LAMBDA
         end
 
         c
       when Liquid::Drop
-        drop = args.shift
+        drop         = args.shift
         drop.context = Context.new([drop, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits)
       when Hash
         Context.new([args.shift, assigns], instance_assigns, registers, @rethrow_errors, @resource_limits)
@@ -187,11 +165,18 @@ module Liquid
         raise ArgumentError, "Expected Hash or Liquid::Context as parameter"
       end
 
+      output = nil
+
+      context_register = context.registers.is_a?(StaticRegisters) ? context.registers.static : context.registers
+
       case args.last
       when Hash
         options = args.pop
+        output  = options[:output] if options[:output]
 
-        registers.merge!(options[:registers]) if options[:registers].is_a?(Hash)
+        options[:registers]&.each do |key, register|
+          context_register[key] = register
+        end
 
         apply_options_to_context(context, options)
       when Module, Array
@@ -201,13 +186,13 @@ module Liquid
       # Retrying a render resets resource usage
       context.resource_limits.reset
 
+      if @profiling && context.profiler.nil?
+        @profiler = context.profiler = Liquid::Profiler.new
+      end
+
       begin
         # render the nodelist.
-        # for performance reasons we get an array back here. join will make a string out of it.
-        result = with_profiling(context) do
-          @root.render(context)
-        end
-        result.respond_to?(:join) ? result.join : result
+        @root.render_to_output_buffer(context, output || +'')
       rescue Liquid::MemoryError => e
         context.handle_error(e)
       ensure
@@ -220,35 +205,31 @@ module Liquid
       render(*args)
     end
 
-    private
-
-    def tokenize(source)
-      Tokenizer.new(source, @line_numbers)
+    def render_to_output_buffer(context, output)
+      render(context, output: output)
     end
 
-    def with_profiling(context)
-      if @profiling && !context.partial
+    private
+
+    def configure_options(options)
+      if (profiling = options[:profile])
         raise "Profiler not loaded, require 'liquid/profiler' first" unless defined?(Liquid::Profiler)
-
-        @profiler = Profiler.new
-        @profiler.start
-
-        begin
-          yield
-        ensure
-          @profiler.stop
-        end
-      else
-        yield
       end
+
+      @options      = options
+      @profiling    = profiling
+      @line_numbers = options[:line_numbers] || @profiling
+      parse_context = options.is_a?(ParseContext) ? options : ParseContext.new(options)
+      @warnings     = parse_context.warnings
+      parse_context
     end
 
     def apply_options_to_context(context, options)
       context.add_filters(options[:filters]) if options[:filters]
-      context.global_filter = options[:global_filter] if options[:global_filter]
+      context.global_filter      = options[:global_filter] if options[:global_filter]
       context.exception_renderer = options[:exception_renderer] if options[:exception_renderer]
-      context.strict_variables = options[:strict_variables] if options[:strict_variables]
-      context.strict_filters = options[:strict_filters] if options[:strict_filters]
+      context.strict_variables   = options[:strict_variables] if options[:strict_variables]
+      context.strict_filters     = options[:strict_filters] if options[:strict_filters]
     end
   end
 end

lib/liquid/template_factory.rb

@@ -0,0 +1,9 @@
+# frozen_string_literal: true
+
+module Liquid
+  class TemplateFactory
+    def for(_template_name)
+      Liquid::Template.new
+    end
+  end
+end

lib/liquid/tokenizer.rb

@@ -1,29 +1,37 @@
+# frozen_string_literal: true
+
 module Liquid
   class Tokenizer
-    attr_reader :line_number
+    attr_reader :line_number, :for_liquid_tag
 
-    def initialize(source, line_numbers = false)
-      @source = source
-      @line_number = line_numbers ? 1 : nil
-      @tokens = tokenize
+    def initialize(source, line_numbers = false, line_number: nil, for_liquid_tag: false)
+      @source         = source.to_s.to_str
+      @line_number    = line_number || (line_numbers ? 1 : nil)
+      @for_liquid_tag = for_liquid_tag
+      @tokens         = tokenize
     end
 
     def shift
-      token = @tokens.shift
-      @line_number += token.count("\n") if @line_number && token
+      (token = @tokens.shift) || return
+
+      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 [] if @source.empty?
+
+      return @source.split("\n") if @for_liquid_tag
 
       tokens = @source.split(TemplateParser)
 
       # removes the rogue empty element at the beginning of the array
-      tokens.shift if tokens[0] && tokens[0].empty?
+      tokens.shift if tokens[0]&.empty?
 
       tokens
     end

lib/liquid/usage.rb

@@ -0,0 +1,8 @@
+# frozen_string_literal: true
+
+module Liquid
+  module Usage
+    def self.increment(name)
+    end
+  end
+end

lib/liquid/utils.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   module Utils
     def self.slice_collection(collection, from, to)
@@ -10,7 +12,7 @@ module Liquid
 
     def self.slice_collection_using_each(collection, from, to)
       segments = []
-      index = 0
+      index    = 0
 
       # Maintains Ruby 1.8.7 String#each behaviour on 1.9
       if collection.is_a?(String)
@@ -46,11 +48,11 @@ module Liquid
     def self.to_number(obj)
       case obj
       when Float
-        BigDecimal.new(obj.to_s)
+        BigDecimal(obj.to_s)
       when Numeric
         obj
       when String
-        (obj.strip =~ /\A-?\d+\.\d+\z/) ? BigDecimal.new(obj) : obj.to_i
+        /\A-?\d+\.\d+\z/.match?(obj.strip) ? BigDecimal(obj) : obj.to_i
       else
         if obj.respond_to?(:to_number)
           obj.to_number
@@ -69,7 +71,7 @@ module Liquid
       end
 
       case obj
-      when 'now'.freeze, 'today'.freeze
+      when 'now', 'today'
         Time.now
       when /\A\d+\z/, Integer
         Time.at(obj.to_i)
@@ -79,5 +81,13 @@ module Liquid
     rescue ::ArgumentError
       nil
     end
+
+    def self.to_liquid_value(obj)
+      # Enable "obj" to represent itself as a primitive value like integer, string, or boolean
+      return obj.to_liquid_value if obj.respond_to?(:to_liquid_value)
+
+      # Otherwise return the object itself
+      obj
+    end
   end
 end

lib/liquid/variable.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Holds variables. Variables are only loaded "just in time"
   # and are not evaluated as part of the render stage
@@ -10,19 +12,25 @@ module Liquid
   #   {{ user | link }}
   #
   class Variable
-    FilterParser = /(?:\s+|#{QuotedFragment}|#{ArgumentSeparator})+/o
+    FilterMarkupRegex        = /#{FilterSeparator}\s*(.*)/om
+    FilterParser             = /(?:\s+|#{QuotedFragment}|#{ArgumentSeparator})+/o
+    FilterArgsRegex          = /(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o
+    JustTagAttributes        = /\A#{TagAttributes}\z/o
+    MarkupWithQuotedFragment = /(#{QuotedFragment})(.*)/om
+
     attr_accessor :filters, :name, :line_number
     attr_reader :parse_context
     alias_method :options, :parse_context
+
     include ParserSwitching
 
     def initialize(markup, parse_context)
-      @markup  = markup
-      @name    = nil
+      @markup        = markup
+      @name          = nil
       @parse_context = parse_context
-      @line_number = parse_context.line_number
+      @line_number   = parse_context.line_number
 
-      parse_with_selected_parser(markup)
+      strict_parse_with_error_mode_fallback(markup)
     end
 
     def raw
@@ -35,17 +43,17 @@ module Liquid
 
     def lax_parse(markup)
       @filters = []
-      return unless markup =~ /(#{QuotedFragment})(.*)/om
+      return unless markup =~ MarkupWithQuotedFragment
 
-      name_markup = $1
-      filter_markup = $2
-      @name = Expression.parse(name_markup)
-      if filter_markup =~ /#{FilterSeparator}\s*(.*)/om
-        filters = $1.scan(FilterParser)
+      name_markup   = Regexp.last_match(1)
+      filter_markup = Regexp.last_match(2)
+      @name         = Expression.parse(name_markup)
+      if filter_markup =~ FilterMarkupRegex
+        filters = Regexp.last_match(1).scan(FilterParser)
         filters.each do |f|
           next unless f =~ /\w+/
           filtername = Regexp.last_match(0)
-          filterargs = f.scan(/(?:#{FilterArgumentSeparator}|#{ArgumentSeparator})\s*((?:\w+\s*\:\s*)?#{QuotedFragment})/o).flatten
+          filterargs = f.scan(FilterArgsRegex).flatten
           @filters << parse_filter_expressions(filtername, filterargs)
         end
       end
@@ -55,6 +63,8 @@ module Liquid
       @filters = []
       p = Parser.new(markup)
 
+      return if p.look(:end_of_string)
+
       @name = Expression.parse(p.expression)
       while p.consume?(:pipe)
         filtername = p.consume(:id)
@@ -73,37 +83,57 @@ module Liquid
     end
 
     def render(context)
-      obj = @filters.inject(context.evaluate(@name)) do |output, (filter_name, filter_args, filter_kwargs)|
+      obj = context.evaluate(@name)
+
+      @filters.each do |filter_name, filter_args, filter_kwargs|
         filter_args = evaluate_filter_expressions(context, filter_args, filter_kwargs)
-        context.invoke(filter_name, output, *filter_args)
+        obj = context.invoke(filter_name, obj, *filter_args)
       end
 
-      obj = context.apply_global_filter(obj)
+      context.apply_global_filter(obj)
+    end
 
-      taint_check(context, obj)
+    def render_to_output_buffer(context, output)
+      obj = render(context)
 
-      obj
+      if obj.is_a?(Array)
+        output << obj.join
+      elsif obj.nil?
+      else
+        output << obj.to_s
+      end
+
+      output
+    end
+
+    def disabled?(_context)
+      false
+    end
+
+    def disabled_tags
+      []
     end
 
     private
 
     def parse_filter_expressions(filter_name, unparsed_args)
-      filter_args = []
-      keyword_args = {}
+      filter_args  = []
+      keyword_args = nil
       unparsed_args.each do |a|
-        if matches = a.match(/\A#{TagAttributes}\z/o)
+        if (matches = a.match(JustTagAttributes))
+          keyword_args           ||= {}
           keyword_args[matches[1]] = Expression.parse(matches[2])
         else
           filter_args << Expression.parse(a)
         end
       end
       result = [filter_name, filter_args]
-      result << keyword_args unless keyword_args.empty?
+      result << keyword_args if keyword_args
       result
     end
 
     def evaluate_filter_expressions(context, filter_args, filter_kwargs)
-      parsed_args = filter_args.map{ |expr| context.evaluate(expr) }
+      parsed_args = filter_args.map { |expr| context.evaluate(expr) }
       if filter_kwargs
         parsed_kwargs = {}
         filter_kwargs.each do |key, expr|
@@ -114,22 +144,9 @@ module Liquid
       parsed_args
     end
 
-    def taint_check(context, obj)
-      return unless obj.tainted?
-      return if Template.taint_mode == :lax
-
-      @markup =~ QuotedFragment
-      name = Regexp.last_match(0)
-
-      error = TaintedError.new("variable '#{name}' is tainted and was not escaped")
-      error.line_number = line_number
-      error.template_name = context.template_name
-
-      case Template.taint_mode
-      when :warn
-        context.warnings << error
-      when :error
-        raise error
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        [@node.name] + @node.filters.flatten
       end
     end
   end

lib/liquid/variable_lookup.rb

@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 module Liquid
   class VariableLookup
     SQUARE_BRACKETED = /\A\[(.*)\]\z/m
-    COMMAND_METHODS = ['size'.freeze, 'first'.freeze, 'last'.freeze]
+    COMMAND_METHODS  = ['size', 'first', 'last'].freeze
 
     attr_reader :name, :lookups
 
@@ -14,17 +16,17 @@ module Liquid
 
       name = lookups.shift
       if name =~ SQUARE_BRACKETED
-        name = Expression.parse($1)
+        name = Expression.parse(Regexp.last_match(1))
       end
       @name = name
 
-      @lookups = lookups
+      @lookups       = lookups
       @command_flags = 0
 
       @lookups.each_index do |i|
         lookup = lookups[i]
         if lookup =~ SQUARE_BRACKETED
-          lookups[i] = Expression.parse($1)
+          lookups[i] = Expression.parse(Regexp.last_match(1))
         elsif COMMAND_METHODS.include?(lookup)
           @command_flags |= 1 << i
         end
@@ -32,12 +34,15 @@ module Liquid
     end
 
     def evaluate(context)
-      name = context.evaluate(@name)
+      name   = context.evaluate(@name)
       object = context.find_variable(name)
 
       @lookups.each_index do |i|
         key = context.evaluate(@lookups[i])
 
+        # Cast "key" to its liquid value to enable it to act as a primitive value
+        key = Liquid::Utils.to_liquid_value(key)
+
         # If object is a hash- or array-like object we look for the
         # presence of the key and if its available we return it
         if object.respond_to?(:[]) &&
@@ -45,7 +50,7 @@ module Liquid
              (object.respond_to?(:fetch) && key.is_a?(Integer)))
 
           # if its a proc we will replace the entry with the proc
-          res = context.lookup_and_evaluate(object, key)
+          res    = context.lookup_and_evaluate(object, key)
           object = res.to_liquid
 
           # Some special cases. If the part wasn't in square brackets and
@@ -78,5 +83,11 @@ module Liquid
     def state
       [@name, @lookups, @command_flags]
     end
+
+    class ParseTreeVisitor < Liquid::ParseTreeVisitor
+      def children
+        @node.lookups
+      end
+    end
   end
 end

lib/liquid/version.rb

@@ -1,4 +1,6 @@
 # encoding: utf-8
+# frozen_string_literal: true
+
 module Liquid
-  VERSION = "4.0.0"
+  VERSION = "5.3.0.alpha"
 end

liquid.gemspec

@@ -1,6 +1,8 @@
 # encoding: utf-8
+# frozen_string_literal: true
+
 lib = File.expand_path('../lib/', __FILE__)
-$LOAD_PATH.unshift lib unless $LOAD_PATH.include?(lib)
+$LOAD_PATH.unshift(lib) unless $LOAD_PATH.include?(lib)
 
 require "liquid/version"
 
@@ -15,9 +17,11 @@ 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     = ">= 2.1.0"
+  s.required_ruby_version     = ">= 2.5.0"
   s.required_rubygems_version = ">= 1.3.7"
 
+  s.metadata['allowed_push_host'] = 'https://rubygems.org'
+
   s.test_files  = Dir.glob("{test}/**/*")
   s.files       = Dir.glob("{lib}/**/*") + %w(LICENSE README.md)
 
@@ -25,6 +29,6 @@ Gem::Specification.new do |s|
 
   s.require_path = "lib"
 
-  s.add_development_dependency 'rake', '~> 11.3'
-  s.add_development_dependency 'minitest'
+  s.add_development_dependency('rake', '~> 13.0')
+  s.add_development_dependency('minitest')
 end

performance/benchmark.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'benchmark/ips'
 require_relative 'theme_runner'
 
@@ -5,7 +7,7 @@ Liquid::Template.error_mode = ARGV.first.to_sym if ARGV.first
 profiler = ThemeRunner.new
 
 Benchmark.ips do |x|
-  x.time = 10
+  x.time   = 10
   x.warmup = 5
 
   puts

performance/memory_profile.rb

@@ -0,0 +1,63 @@
+# frozen_string_literal: true
+
+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 self.run
+    puts
+    yield new
+  end
+
+  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
+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

performance/profile.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'stackprof'
 require_relative 'theme_runner'
 
@@ -13,7 +15,7 @@ profiler.run
     end
   end
 
-  if profile_type == :cpu && graph_filename = ENV['GRAPH_FILENAME']
+  if profile_type == :cpu && (graph_filename = ENV['GRAPH_FILENAME'])
     File.open(graph_filename, 'w') do |f|
       StackProf::Report.new(results).print_graphviz(nil, f)
     end

performance/shopify/comment_form.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class CommentForm < Liquid::Block
   Syntax = /(#{Liquid::VariableSignature}+)/
 
@@ -5,14 +7,14 @@ class CommentForm < Liquid::Block
     super
 
     if markup =~ Syntax
-      @variable_name = $1
-      @attributes = {}
+      @variable_name = Regexp.last_match(1)
+      @attributes    = {}
     else
-      raise SyntaxError.new("Syntax Error in 'comment_form' - Valid syntax: comment_form [article]")
+      raise SyntaxError, "Syntax Error in 'comment_form' - Valid syntax: comment_form [article]"
     end
   end
 
-  def render(context)
+  def render_to_output_buffer(context, output)
     article = context[@variable_name]
 
     context.stack do
@@ -20,10 +22,12 @@ class CommentForm < Liquid::Block
         'posted_successfully?' => context.registers[:posted_successfully],
         'errors' => context['comment.errors'],
         'author' => context['comment.author'],
-        'email'  => context['comment.email'],
-        'body'   => context['comment.body']
+        'email' => context['comment.email'],
+        'body' => context['comment.body'],
       }
-      wrap_in_form(article, render_all(@nodelist, context))
+
+      output << wrap_in_form(article, render_all(@nodelist, context, output))
+      output
     end
   end
 

performance/shopify/database.rb

@@ -1,11 +1,21 @@
+# frozen_string_literal: true
+
 require 'yaml'
 
 module Database
+  DATABASE_FILE_PATH = "#{__dir__}/vision.database.yml"
+
   # Load the standard vision toolkit database and re-arrage it to be simply exportable
   # to liquid as assigns. All this is based on Shopify
   def self.tables
     @tables ||= begin
-      db = YAML.load_file("#{__dir__}/vision.database.yml")
+      db =
+        if YAML.respond_to?(:unsafe_load_file) # Only Psych 4+ can use unsafe_load_file
+          # unsafe_load_file is needed for YAML references
+          YAML.unsafe_load_file(DATABASE_FILE_PATH)
+        else
+          YAML.load_file(DATABASE_FILE_PATH)
+        end
 
       # From vision source
       db['products'].each do |product|
@@ -16,9 +26,10 @@ module Database
       end
 
       # key the tables by handles, as this is how liquid expects it.
-      db = db.inject({}) do |assigns, (key, values)|
-        assigns[key] = values.inject({}) { |h, v| h[v['handle']] = v; h; }
-        assigns
+      db = db.each_with_object({}) do |(key, values), assigns|
+        assigns[key] = values.each_with_object({}) do |v, h|
+          h[v['handle']] = v
+        end
       end
 
       # Some standard direct accessors so that the specialized templates
@@ -29,9 +40,9 @@ module Database
       db['article']    = db['blog']['articles'].first
 
       db['cart']       = {
-        'total_price' => db['line_items'].values.inject(0) { |sum, item| sum += item['line_price'] * item['quantity'] },
-        'item_count'  => db['line_items'].values.inject(0) { |sum, item| sum += item['quantity'] },
-        'items'       => db['line_items'].values
+        'total_price' => db['line_items'].values.inject(0) { |sum, item| sum + item['line_price'] * item['quantity'] },
+        'item_count' => db['line_items'].values.inject(0) { |sum, item| sum + item['quantity'] },
+        'items' => db['line_items'].values,
       }
 
       db
@@ -40,6 +51,6 @@ module Database
 end
 
 if __FILE__ == $PROGRAM_NAME
-  p Database.tables['collections']['frontpage'].keys
+  p(Database.tables['collections']['frontpage'].keys)
   # p Database.tables['blog']['articles']
 end

performance/shopify/json_filter.rb

@@ -1,7 +1,9 @@
+# frozen_string_literal: true
+
 require 'json'
 
 module JsonFilter
   def json(object)
-    JSON.dump(object.reject { |k, v| k == "collections" })
+    JSON.dump(object.reject { |k, _v| k == "collections" })
   end
 end

performance/shopify/liquid.rb

@@ -1,4 +1,6 @@
-$:.unshift __dir__ + '/../../lib'
+# frozen_string_literal: true
+
+$LOAD_PATH.unshift(__dir__ + '/../../lib')
 require_relative '../../lib/liquid'
 
 require_relative 'comment_form'
@@ -9,11 +11,11 @@ require_relative 'shop_filter'
 require_relative 'tag_filter'
 require_relative 'weight_filter'
 
-Liquid::Template.register_tag 'paginate', Paginate
-Liquid::Template.register_tag 'form', CommentForm
+Liquid::Template.register_tag('paginate', Paginate)
+Liquid::Template.register_tag('form', CommentForm)
 
-Liquid::Template.register_filter JsonFilter
-Liquid::Template.register_filter MoneyFilter
-Liquid::Template.register_filter WeightFilter
-Liquid::Template.register_filter ShopFilter
-Liquid::Template.register_filter TagFilter
+Liquid::Template.register_filter(JsonFilter)
+Liquid::Template.register_filter(MoneyFilter)
+Liquid::Template.register_filter(WeightFilter)
+Liquid::Template.register_filter(ShopFilter)
+Liquid::Template.register_filter(TagFilter)

performance/shopify/money_filter.rb

@@ -1,12 +1,14 @@
+# frozen_string_literal: true
+
 module MoneyFilter
   def money_with_currency(money)
     return '' if money.nil?
-    sprintf("$ %.2f USD", money / 100.0)
+    format("$ %.2f USD", money / 100.0)
   end
 
   def money(money)
     return '' if money.nil?
-    sprintf("$ %.2f", money / 100.0)
+    format("$ %.2f", money / 100.0)
   end
 
   private

performance/shopify/paginate.rb

@@ -1,13 +1,15 @@
+# frozen_string_literal: true
+
 class Paginate < Liquid::Block
-  Syntax     = /(#{Liquid::QuotedFragment})\s*(by\s*(\d+))?/
+  Syntax = /(#{Liquid::QuotedFragment})\s*(by\s*(\d+))?/
 
   def initialize(tag_name, markup, options)
     super
 
     if markup =~ Syntax
-      @collection_name = $1
-      @page_size = if $2
-        $3.to_i
+      @collection_name = Regexp.last_match(1)
+      @page_size       = if Regexp.last_match(2)
+        Regexp.last_match(3).to_i
       else
         20
       end
@@ -17,27 +19,27 @@ class Paginate < Liquid::Block
         @attributes[key] = value
       end
     else
-      raise SyntaxError.new("Syntax Error in tag 'paginate' - Valid syntax: paginate [collection] by number")
+      raise SyntaxError, "Syntax Error in tag 'paginate' - Valid syntax: paginate [collection] by number"
     end
   end
 
-  def render(context)
+  def render_to_output_buffer(context, output)
     @context = context
 
     context.stack do
-      current_page  = context['current_page'].to_i
+      current_page = context['current_page'].to_i
 
       pagination = {
-        'page_size'      => @page_size,
-        'current_page'   => 5,
-        'current_offset' => @page_size * 5
+        'page_size' => @page_size,
+        'current_page' => 5,
+        'current_offset' => @page_size * 5,
       }
 
       context['paginate'] = pagination
 
-      collection_size  = context[@collection_name].size
+      collection_size = context[@collection_name].size
 
-      raise ArgumentError.new("Cannot paginate array '#{@collection_name}'. Not found.") if collection_size.nil?
+      raise ArgumentError, "Cannot paginate array '#{@collection_name}'. Not found." if collection_size.nil?
 
       page_count = (collection_size.to_f / @page_size.to_f).to_f.ceil + 1
 

performance/shopify/shop_filter.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ShopFilter
   def asset_url(input)
     "/files/1/[shop_id]/[shop_id]/assets/#{input}"
@@ -29,7 +31,7 @@ module ShopFilter
 
   def link_to_vendor(vendor)
     if vendor
-      link_to vendor, url_for_vendor(vendor), vendor
+      link_to(vendor, url_for_vendor(vendor), vendor)
     else
       'Unknown Vendor'
     end
@@ -37,7 +39,7 @@ module ShopFilter
 
   def link_to_type(type)
     if type
-      link_to type, url_for_type(type), type
+      link_to(type, url_for_type(type), type)
     else
       'Unknown Vendor'
     end
@@ -52,15 +54,15 @@ module ShopFilter
   end
 
   def product_img_url(url, style = 'small')
-    unless url =~ /\Aproducts\/([\w\-\_]+)\.(\w{2,4})/
+    unless url =~ %r{\Aproducts/([\w\-\_]+)\.(\w{2,4})}
       raise ArgumentError, 'filter "size" can only be called on product images'
     end
 
     case style
     when 'original'
-      return '/files/shops/random_number/' + url
+      '/files/shops/random_number/' + url
     when 'grande', 'large', 'medium', 'compact', 'small', 'thumb', 'icon'
-      "/files/shops/random_number/products/#{$1}_#{style}.#{$2}"
+      "/files/shops/random_number/products/#{Regexp.last_match(1)}_#{style}.#{Regexp.last_match(2)}"
     else
       raise ArgumentError, 'valid parameters for filter "size" are: original, grande, large, medium, compact, small, thumb and icon '
     end
@@ -70,16 +72,14 @@ module ShopFilter
     html = []
     html << %(<span class="prev">#{link_to(paginate['previous']['title'], paginate['previous']['url'])}</span>) if paginate['previous']
 
-    for part in paginate['parts']
-
-      if part['is_link']
-        html << %(<span class="page">#{link_to(part['title'], part['url'])}</span>)
+    paginate['parts'].each do |part|
+      html << if part['is_link']
+        %(<span class="page">#{link_to(part['title'], part['url'])}</span>)
       elsif part['title'].to_i == paginate['current_page'].to_i
-        html << %(<span class="page current">#{part['title']}</span>)
+        %(<span class="page current">#{part['title']}</span>)
       else
-        html << %(<span class="deco">#{part['title']}</span>)
+        %(<span class="deco">#{part['title']}</span>)
       end
-
     end
 
     html << %(<span class="next">#{link_to(paginate['next']['title'], paginate['next']['url'])}</span>) if paginate['next']

performance/shopify/tag_filter.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module TagFilter
   def link_to_tag(label, tag)
     "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tag}\">#{label}</a>"
@@ -13,11 +15,11 @@ module TagFilter
 
   def link_to_add_tag(label, tag)
     tags = (@context['current_tags'] + [tag]).uniq
-    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join("+")}\">#{label}</a>"
+    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join('+')}\">#{label}</a>"
   end
 
   def link_to_remove_tag(label, tag)
     tags = (@context['current_tags'] - [tag]).uniq
-    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join("+")}\">#{label}</a>"
+    "<a title=\"Show tag #{tag}\" href=\"/collections/#{@context['handle']}/#{tags.join('+')}\">#{label}</a>"
   end
 end

performance/shopify/weight_filter.rb

@@ -1,6 +1,8 @@
+# frozen_string_literal: true
+
 module WeightFilter
   def weight(grams)
-    sprintf("%.2f", grams / 1000)
+    format("%.2f", grams / 1000)
   end
 
   def weight_with_unit(grams)

performance/theme_runner.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 # This profiler run simulates Shopify.
 # We are looking in the tests directory for liquid files and render them within the designated layout file.
 # We will also export a substantial database to liquid which the templates can render values of.
@@ -31,7 +33,7 @@ class ThemeRunner
       {
         liquid: File.read(test),
         layout: (File.file?(theme_path) ? File.read(theme_path) : nil),
-        template_name: test
+        template_name: test,
       }
     end.compact
 
@@ -56,9 +58,9 @@ class ThemeRunner
   # `render` is called to benchmark just the render portion of liquid
   def render
     @compiled_tests.each do |test|
-      tmpl = test[:tmpl]
+      tmpl    = test[:tmpl]
       assigns = test[:assigns]
-      layout = test[:layout]
+      layout  = test[:layout]
 
       if layout
         assigns['content_for_layout'] = tmpl.render!(assigns)
@@ -71,10 +73,14 @@ class ThemeRunner
 
   private
 
+  def render_layout(template, layout, assigns)
+    assigns['content_for_layout'] = template.render!(assigns)
+    layout&.render!(assigns)
+  end
+
   def compile_and_render(template, layout, assigns, page_template, template_file)
     compiled_test = compile_test(template, layout, assigns, page_template, template_file)
-    assigns['content_for_layout'] = compiled_test[:tmpl].render!(assigns)
-    compiled_test[:layout].render!(assigns) if layout
+    render_layout(compiled_test[:tmpl], compiled_test[:layout], compiled_test[:assigns])
   end
 
   def compile_all_tests
@@ -86,7 +92,7 @@ class ThemeRunner
   end
 
   def compile_test(template, layout, assigns, page_template, template_file)
-    tmpl = init_template(page_template, template_file)
+    tmpl            = init_template(page_template, template_file)
     parsed_template = tmpl.parse(template).dup
 
     if layout
@@ -111,9 +117,9 @@ class ThemeRunner
 
   # set up a new Liquid::Template object for use in `compile_and_render` and `compile_test`
   def init_template(page_template, template_file)
-    tmpl = Liquid::Template.new
-    tmpl.assigns['page_title'] = 'Page title'
-    tmpl.assigns['template'] = page_template
+    tmpl                         = Liquid::Template.new
+    tmpl.assigns['page_title']   = 'Page title'
+    tmpl.assigns['template']     = page_template
     tmpl.registers[:file_system] = ThemeRunner::FileSystem.new(File.dirname(template_file))
     tmpl
   end

test/integration/assign_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class AssignTest < Minitest::Test
@@ -8,9 +10,9 @@ class AssignTest < Minitest::Test
     {% assign this-thing = 'Print this-thing' %}
     {{ this-thing }}
     END_TEMPLATE
-    template = Template.parse(template_source)
-    rendered = template.render!
-    assert_equal "Print this-thing", rendered.strip
+    template        = Template.parse(template_source)
+    rendered        = template.render!
+    assert_equal("Print this-thing", rendered.strip)
   end
 
   def test_assigned_variable
@@ -42,7 +44,74 @@ class AssignTest < Minitest::Test
       end
     end
     with_error_mode(:lax) do
-      assert Template.parse("{% assign foo = ('X' | downcase) %}")
+      assert(Template.parse("{% assign foo = ('X' | downcase) %}"))
     end
   end
-end # AssignTest
+
+  def test_expression_with_whitespace_in_square_brackets
+    source = "{% assign r = a[ 'b' ] %}{{ r }}"
+    assert_template_result('result', source, 'a' => { 'b' => 'result' })
+  end
+
+  def test_assign_score_exceeding_resource_limit
+    t = Template.parse("{% assign foo = 42 %}{% assign bar = 23 %}")
+    t.resource_limits.assign_score_limit = 1
+    assert_equal("Liquid error: Memory limits exceeded", t.render)
+    assert(t.resource_limits.reached?)
+
+    t.resource_limits.assign_score_limit = 2
+    assert_equal("", t.render!)
+    refute_nil(t.resource_limits.assign_score)
+  end
+
+  def test_assign_score_exceeding_limit_from_composite_object
+    t = Template.parse("{% assign foo = 'aaaa' | reverse %}")
+
+    t.resource_limits.assign_score_limit = 3
+    assert_equal("Liquid error: Memory limits exceeded", t.render)
+    assert(t.resource_limits.reached?)
+
+    t.resource_limits.assign_score_limit = 5
+    assert_equal("", t.render!)
+  end
+
+  def test_assign_score_of_int
+    assert_equal(1, assign_score_of(123))
+  end
+
+  def test_assign_score_of_string_counts_bytes
+    assert_equal(3, assign_score_of('123'))
+    assert_equal(5, assign_score_of('12345'))
+    assert_equal(9, assign_score_of('すごい'))
+  end
+
+  def test_assign_score_of_array
+    assert_equal(1, assign_score_of([]))
+    assert_equal(2, assign_score_of([123]))
+    assert_equal(6, assign_score_of([123, 'abcd']))
+  end
+
+  def test_assign_score_of_hash
+    assert_equal(1, assign_score_of({}))
+    assert_equal(5, assign_score_of('int' => 123))
+    assert_equal(12, assign_score_of('int' => 123, 'str' => 'abcd'))
+  end
+
+  private
+
+  class ObjectWrapperDrop < Liquid::Drop
+    def initialize(obj)
+      @obj = obj
+    end
+
+    def value
+      @obj
+    end
+  end
+
+  def assign_score_of(obj)
+    context = Liquid::Context.new('drop' => ObjectWrapperDrop.new(obj))
+    Liquid::Template.parse('{% assign obj = drop.value %}').render!(context)
+    context.resource_limits.assign_score
+  end
+end

test/integration/blank_test.rb

@@ -1,11 +1,12 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class FoobarTag < Liquid::Tag
-  def render(*args)
-    " "
+  def render_to_output_buffer(_context, output)
+    output << ' '
+    output
   end
-
-  Liquid::Template.register_tag('foobar', FoobarTag)
 end
 
 class BlankTestFileSystem
@@ -31,7 +32,9 @@ class BlankTest < Minitest::Test
   end
 
   def test_new_tags_are_not_blank_by_default
-    assert_template_result(" " * N, wrap_in_for("{% foobar %}"))
+    with_custom_tag('foobar', FoobarTag) do
+      assert_template_result(" " * N, wrap_in_for("{% foobar %}"))
+    end
   end
 
   def test_loops_are_blank
@@ -93,9 +96,9 @@ class BlankTest < Minitest::Test
 
   def test_include_is_blank
     Liquid::Template.file_system = BlankTestFileSystem.new
-    assert_template_result "foobar" * (N + 1), wrap("{% include 'foobar' %}")
-    assert_template_result " foobar " * (N + 1), wrap("{% include ' foobar ' %}")
-    assert_template_result "   " * (N + 1), wrap(" {% include ' ' %} ")
+    assert_template_result("foobar" * (N + 1), wrap("{% include 'foobar' %}"))
+    assert_template_result(" foobar " * (N + 1), wrap("{% include ' foobar ' %}"))
+    assert_template_result("   " * (N + 1), wrap(" {% include ' ' %} "))
   end
 
   def test_case_is_blank

test/integration/block_test.rb

@@ -0,0 +1,58 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class BlockTest < Minitest::Test
+  include Liquid
+
+  def test_unexpected_end_tag
+    exc = assert_raises(SyntaxError) do
+      Template.parse("{% if true %}{% endunless %}")
+    end
+    assert_equal(exc.message, "Liquid syntax error: 'endunless' is not a valid delimiter for if tags. use endif")
+  end
+
+  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
+  end
+end

test/integration/capture_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class CaptureTest < Minitest::Test
@@ -12,9 +14,9 @@ class CaptureTest < Minitest::Test
     {% capture this-thing %}Print this-thing{% endcapture %}
     {{ this-thing }}
     END_TEMPLATE
-    template = Template.parse(template_source)
-    rendered = template.render!
-    assert_equal "Print this-thing", rendered.strip
+    template        = Template.parse(template_source)
+    rendered        = template.render!
+    assert_equal("Print this-thing", rendered.strip)
   end
 
   def test_capture_to_variable_from_outer_scope_if_existing
@@ -28,9 +30,9 @@ class CaptureTest < Minitest::Test
     {% endif %}
     {{var}}
     END_TEMPLATE
-    template = Template.parse(template_source)
-    rendered = template.render!
-    assert_equal "test-string", rendered.gsub(/\s/, '')
+    template        = Template.parse(template_source)
+    rendered        = template.render!
+    assert_equal("test-string", rendered.gsub(/\s/, ''))
   end
 
   def test_assigning_from_capture
@@ -43,8 +45,14 @@ class CaptureTest < Minitest::Test
     {% endfor %}
     {{ first }}-{{ second }}
     END_TEMPLATE
-    template = Template.parse(template_source)
-    rendered = template.render!
-    assert_equal "3-3", rendered.gsub(/\s/, '')
+    template        = Template.parse(template_source)
+    rendered        = template.render!
+    assert_equal("3-3", rendered.gsub(/\s/, ''))
   end
-end # CaptureTest
+
+  def test_increment_assign_score_by_bytes_not_characters
+    t = Template.parse("{% capture foo %}すごい{% endcapture %}")
+    t.render!
+    assert_equal(9, t.resource_limits.assign_score)
+  end
+end

test/integration/context_test.rb

@@ -1,8 +1,596 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
+class HundredCentes
+  def to_liquid
+    100
+  end
+end
+
+class CentsDrop < Liquid::Drop
+  def amount
+    HundredCentes.new
+  end
+
+  def non_zero?
+    true
+  end
+end
+
+class ContextSensitiveDrop < Liquid::Drop
+  def test
+    @context['test']
+  end
+end
+
+class Category
+  attr_accessor :name
+
+  def initialize(name)
+    @name = name
+  end
+
+  def to_liquid
+    CategoryDrop.new(self)
+  end
+end
+
+class CategoryDrop < Liquid::Drop
+  attr_accessor :category, :context
+
+  def initialize(category)
+    @category = category
+  end
+end
+
+class CounterDrop < Liquid::Drop
+  def count
+    @count ||= 0
+    @count  += 1
+  end
+end
+
+class ArrayLike
+  def fetch(index)
+  end
+
+  def [](index)
+    @counts        ||= []
+    @counts[index] ||= 0
+    @counts[index]  += 1
+  end
+
+  def to_liquid
+    self
+  end
+end
+
 class ContextTest < Minitest::Test
   include Liquid
 
+  def setup
+    @context = Liquid::Context.new
+  end
+
+  def test_variables
+    @context['string'] = 'string'
+    assert_equal('string', @context['string'])
+
+    @context['num'] = 5
+    assert_equal(5, @context['num'])
+
+    @context['time'] = Time.parse('2006-06-06 12:00:00')
+    assert_equal(Time.parse('2006-06-06 12:00:00'), @context['time'])
+
+    @context['date'] = Date.today
+    assert_equal(Date.today, @context['date'])
+
+    now = Time.now
+    @context['datetime'] = now
+    assert_equal(now, @context['datetime'])
+
+    @context['bool'] = true
+    assert_equal(true, @context['bool'])
+
+    @context['bool'] = false
+    assert_equal(false, @context['bool'])
+
+    @context['nil'] = nil
+    assert_nil(@context['nil'])
+    assert_nil(@context['nil'])
+  end
+
+  def test_variables_not_existing
+    assert_nil(@context['does_not_exist'])
+  end
+
+  def test_scoping
+    @context.push
+    @context.pop
+
+    assert_raises(Liquid::ContextError) do
+      @context.pop
+    end
+
+    assert_raises(Liquid::ContextError) do
+      @context.push
+      @context.pop
+      @context.pop
+    end
+  end
+
+  def test_length_query
+    @context['numbers'] = [1, 2, 3, 4]
+
+    assert_equal(4, @context['numbers.size'])
+
+    @context['numbers'] = { 1 => 1, 2 => 2, 3 => 3, 4 => 4 }
+
+    assert_equal(4, @context['numbers.size'])
+
+    @context['numbers'] = { 1 => 1, 2 => 2, 3 => 3, 4 => 4, 'size' => 1000 }
+
+    assert_equal(1000, @context['numbers.size'])
+  end
+
+  def test_hyphenated_variable
+    @context['oh-my'] = 'godz'
+    assert_equal('godz', @context['oh-my'])
+  end
+
+  def test_add_filter
+    filter = Module.new do
+      def hi(output)
+        output + ' hi!'
+      end
+    end
+
+    context = Context.new
+    context.add_filters(filter)
+    assert_equal('hi? hi!', context.invoke(:hi, 'hi?'))
+
+    context = Context.new
+    assert_equal('hi?', context.invoke(:hi, 'hi?'))
+
+    context.add_filters(filter)
+    assert_equal('hi? hi!', context.invoke(:hi, 'hi?'))
+  end
+
+  def test_only_intended_filters_make_it_there
+    filter = Module.new do
+      def hi(output)
+        output + ' hi!'
+      end
+    end
+
+    context = Context.new
+    assert_equal("Wookie", context.invoke("hi", "Wookie"))
+
+    context.add_filters(filter)
+    assert_equal("Wookie hi!", context.invoke("hi", "Wookie"))
+  end
+
+  def test_add_item_in_outer_scope
+    @context['test'] = 'test'
+    @context.push
+    assert_equal('test', @context['test'])
+    @context.pop
+    assert_equal('test', @context['test'])
+  end
+
+  def test_add_item_in_inner_scope
+    @context.push
+    @context['test'] = 'test'
+    assert_equal('test', @context['test'])
+    @context.pop
+    assert_nil(@context['test'])
+  end
+
+  def test_hierachical_data
+    @context['hash'] = { "name" => 'tobi' }
+    assert_equal('tobi', @context['hash.name'])
+    assert_equal('tobi', @context['hash["name"]'])
+  end
+
+  def test_keywords
+    assert_equal(true, @context['true'])
+    assert_equal(false, @context['false'])
+  end
+
+  def test_digits
+    assert_equal(100, @context['100'])
+    assert_equal(100.00, @context['100.00'])
+  end
+
+  def test_strings
+    assert_equal("hello!", @context['"hello!"'])
+    assert_equal("hello!", @context["'hello!'"])
+  end
+
+  def test_merge
+    @context.merge("test" => "test")
+    assert_equal('test', @context['test'])
+    @context.merge("test" => "newvalue", "foo" => "bar")
+    assert_equal('newvalue', @context['test'])
+    assert_equal('bar', @context['foo'])
+  end
+
+  def test_array_notation
+    @context['test'] = [1, 2, 3, 4, 5]
+
+    assert_equal(1, @context['test[0]'])
+    assert_equal(2, @context['test[1]'])
+    assert_equal(3, @context['test[2]'])
+    assert_equal(4, @context['test[3]'])
+    assert_equal(5, @context['test[4]'])
+  end
+
+  def test_recoursive_array_notation
+    @context['test'] = { 'test' => [1, 2, 3, 4, 5] }
+
+    assert_equal(1, @context['test.test[0]'])
+
+    @context['test'] = [{ 'test' => 'worked' }]
+
+    assert_equal('worked', @context['test[0].test'])
+  end
+
+  def test_hash_to_array_transition
+    @context['colors'] = {
+      'Blue' => ['003366', '336699', '6699CC', '99CCFF'],
+      'Green' => ['003300', '336633', '669966', '99CC99'],
+      'Yellow' => ['CC9900', 'FFCC00', 'FFFF99', 'FFFFCC'],
+      'Red' => ['660000', '993333', 'CC6666', 'FF9999'],
+    }
+
+    assert_equal('003366', @context['colors.Blue[0]'])
+    assert_equal('FF9999', @context['colors.Red[3]'])
+  end
+
+  def test_try_first
+    @context['test'] = [1, 2, 3, 4, 5]
+
+    assert_equal(1, @context['test.first'])
+    assert_equal(5, @context['test.last'])
+
+    @context['test'] = { 'test' => [1, 2, 3, 4, 5] }
+
+    assert_equal(1, @context['test.test.first'])
+    assert_equal(5, @context['test.test.last'])
+
+    @context['test'] = [1]
+    assert_equal(1, @context['test.first'])
+    assert_equal(1, @context['test.last'])
+  end
+
+  def test_access_hashes_with_hash_notation
+    @context['products'] = { 'count' => 5, 'tags' => ['deepsnow', 'freestyle'] }
+    @context['product']  = { 'variants' => [{ 'title' => 'draft151cm' }, { 'title' => 'element151cm' }] }
+
+    assert_equal(5, @context['products["count"]'])
+    assert_equal('deepsnow', @context['products["tags"][0]'])
+    assert_equal('deepsnow', @context['products["tags"].first'])
+    assert_equal('draft151cm', @context['product["variants"][0]["title"]'])
+    assert_equal('element151cm', @context['product["variants"][1]["title"]'])
+    assert_equal('draft151cm', @context['product["variants"][0]["title"]'])
+    assert_equal('element151cm', @context['product["variants"].last["title"]'])
+  end
+
+  def test_access_variable_with_hash_notation
+    @context['foo'] = 'baz'
+    @context['bar'] = 'foo'
+
+    assert_equal('baz', @context['["foo"]'])
+    assert_equal('baz', @context['[bar]'])
+  end
+
+  def test_access_hashes_with_hash_access_variables
+    @context['var']      = 'tags'
+    @context['nested']   = { 'var' => 'tags' }
+    @context['products'] = { 'count' => 5, 'tags' => ['deepsnow', 'freestyle'] }
+
+    assert_equal('deepsnow', @context['products[var].first'])
+    assert_equal('freestyle', @context['products[nested.var].last'])
+  end
+
+  def test_hash_notation_only_for_hash_access
+    @context['array'] = [1, 2, 3, 4, 5]
+    @context['hash']  = { 'first' => 'Hello' }
+
+    assert_equal(1, @context['array.first'])
+    assert_nil(@context['array["first"]'])
+    assert_equal('Hello', @context['hash["first"]'])
+  end
+
+  def test_first_can_appear_in_middle_of_callchain
+    @context['product'] = { 'variants' => [{ 'title' => 'draft151cm' }, { 'title' => 'element151cm' }] }
+
+    assert_equal('draft151cm', @context['product.variants[0].title'])
+    assert_equal('element151cm', @context['product.variants[1].title'])
+    assert_equal('draft151cm', @context['product.variants.first.title'])
+    assert_equal('element151cm', @context['product.variants.last.title'])
+  end
+
+  def test_cents
+    @context.merge("cents" => HundredCentes.new)
+    assert_equal(100, @context['cents'])
+  end
+
+  def test_nested_cents
+    @context.merge("cents" => { 'amount' => HundredCentes.new })
+    assert_equal(100, @context['cents.amount'])
+
+    @context.merge("cents" => { 'cents' => { 'amount' => HundredCentes.new } })
+    assert_equal(100, @context['cents.cents.amount'])
+  end
+
+  def test_cents_through_drop
+    @context.merge("cents" => CentsDrop.new)
+    assert_equal(100, @context['cents.amount'])
+  end
+
+  def test_nested_cents_through_drop
+    @context.merge("vars" => { "cents" => CentsDrop.new })
+    assert_equal(100, @context['vars.cents.amount'])
+  end
+
+  def test_drop_methods_with_question_marks
+    @context.merge("cents" => CentsDrop.new)
+    assert(@context['cents.non_zero?'])
+  end
+
+  def test_context_from_within_drop
+    @context.merge("test" => '123', "vars" => ContextSensitiveDrop.new)
+    assert_equal('123', @context['vars.test'])
+  end
+
+  def test_nested_context_from_within_drop
+    @context.merge("test" => '123', "vars" => { "local" => ContextSensitiveDrop.new })
+    assert_equal('123', @context['vars.local.test'])
+  end
+
+  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)'])
+  end
+
+  def test_cents_through_drop_nestedly
+    @context.merge("cents" => { "cents" => CentsDrop.new })
+    assert_equal(100, @context['cents.cents.amount'])
+
+    @context.merge("cents" => { "cents" => { "cents" => CentsDrop.new } })
+    assert_equal(100, @context['cents.cents.cents.amount'])
+  end
+
+  def test_drop_with_variable_called_only_once
+    @context['counter'] = CounterDrop.new
+
+    assert_equal(1, @context['counter.count'])
+    assert_equal(2, @context['counter.count'])
+    assert_equal(3, @context['counter.count'])
+  end
+
+  def test_drop_with_key_called_only_once
+    @context['counter'] = CounterDrop.new
+
+    assert_equal(1, @context['counter["count"]'])
+    assert_equal(2, @context['counter["count"]'])
+    assert_equal(3, @context['counter["count"]'])
+  end
+
+  def test_proc_as_variable
+    @context['dynamic'] = proc { 'Hello' }
+
+    assert_equal('Hello', @context['dynamic'])
+  end
+
+  def test_lambda_as_variable
+    @context['dynamic'] = proc { 'Hello' }
+
+    assert_equal('Hello', @context['dynamic'])
+  end
+
+  def test_nested_lambda_as_variable
+    @context['dynamic'] = { "lambda" => proc { 'Hello' } }
+
+    assert_equal('Hello', @context['dynamic.lambda'])
+  end
+
+  def test_array_containing_lambda_as_variable
+    @context['dynamic'] = [1, 2, proc { 'Hello' }, 4, 5]
+
+    assert_equal('Hello', @context['dynamic[2]'])
+  end
+
+  def test_lambda_is_called_once
+    @global = 0
+
+    @context['callcount'] = proc {
+      @global += 1
+      @global.to_s
+    }
+
+    assert_equal('1', @context['callcount'])
+    assert_equal('1', @context['callcount'])
+    assert_equal('1', @context['callcount'])
+  end
+
+  def test_nested_lambda_is_called_once
+    @global = 0
+
+    @context['callcount'] = { "lambda" => proc {
+                                            @global += 1
+                                            @global.to_s
+                                          } }
+
+    assert_equal('1', @context['callcount.lambda'])
+    assert_equal('1', @context['callcount.lambda'])
+    assert_equal('1', @context['callcount.lambda'])
+  end
+
+  def test_lambda_in_array_is_called_once
+    @global = 0
+
+    @context['callcount'] = [1, 2, proc {
+                                     @global += 1
+                                     @global.to_s
+                                   }, 4, 5]
+
+    assert_equal('1', @context['callcount[2]'])
+    assert_equal('1', @context['callcount[2]'])
+    assert_equal('1', @context['callcount[2]'])
+  end
+
+  def test_access_to_context_from_proc
+    @context.registers[:magic] = 345392
+
+    @context['magic'] = proc { @context.registers[:magic] }
+
+    assert_equal(345392, @context['magic'])
+  end
+
+  def test_to_liquid_and_context_at_first_level
+    @context['category'] = Category.new("foobar")
+    assert_kind_of(CategoryDrop, @context['category'])
+    assert_equal(@context, @context['category'].context)
+  end
+
+  def test_interrupt_avoids_object_allocations
+    @context.interrupt? # ruby 3.0.0 allocates on the first call
+    assert_no_object_allocations do
+      @context.interrupt?
+    end
+  end
+
+  def test_context_initialization_with_a_proc_in_environment
+    contx = Context.new([test: ->(c) { c['poutine'] }], test: :foo)
+
+    assert(contx)
+    assert_nil(contx['poutine'])
+  end
+
+  def test_apply_global_filter
+    global_filter_proc = ->(output) { "#{output} filtered" }
+
+    context = Context.new
+    context.global_filter = global_filter_proc
+
+    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({}, {}, StaticRegisters.new(registers))
+    super_context.registers[:my_register] = :my_alt_value
+    subcontext                            = super_context.new_isolated_subcontext
+    assert_equal(:my_value, subcontext.registers[:my_register])
+  end
+
+  def test_new_isolated_subcontext_inherits_static_registers
+    super_context = Context.build(registers: { my_register: :my_value })
+    subcontext    = super_context.new_isolated_subcontext
+    assert_equal(:my_value, subcontext.registers[:my_register])
+  end
+
+  def test_new_isolated_subcontext_registers_do_not_pollute_context
+    super_context                      = Context.build(registers: { my_register: :my_value })
+    subcontext                         = super_context.new_isolated_subcontext
+    subcontext.registers[:my_register] = :my_alt_value
+    assert_equal(:my_value, super_context.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
+
+  def test_disables_tag_specified
+    context = Context.new
+    context.with_disabled_tags(%w(foo bar)) do
+      assert_equal(true, context.tag_disabled?("foo"))
+      assert_equal(true, context.tag_disabled?("bar"))
+      assert_equal(false, context.tag_disabled?("unknown"))
+    end
+  end
+
+  def test_disables_nested_tags
+    context = Context.new
+    context.with_disabled_tags(["foo"]) do
+      context.with_disabled_tags(["foo"]) do
+        assert_equal(true, context.tag_disabled?("foo"))
+        assert_equal(false, context.tag_disabled?("bar"))
+      end
+      context.with_disabled_tags(["bar"]) do
+        assert_equal(true, context.tag_disabled?("foo"))
+        assert_equal(true, context.tag_disabled?("bar"))
+        context.with_disabled_tags(["foo"]) do
+          assert_equal(true, context.tag_disabled?("foo"))
+          assert_equal(true, context.tag_disabled?("bar"))
+        end
+      end
+      assert_equal(true, context.tag_disabled?("foo"))
+      assert_equal(false, context.tag_disabled?("bar"))
+    end
+  end
+
   def test_override_global_filter
     global = Module.new do
       def notice(output)
@@ -17,16 +605,30 @@ class ContextTest < Minitest::Test
     end
 
     with_global_filter(global) do
-      assert_equal 'Global test', Template.parse("{{'test' | notice }}").render!
-      assert_equal 'Local test', Template.parse("{{'test' | notice }}").render!({}, filters: [local])
+      assert_equal('Global test', Template.parse("{{'test' | notice }}").render!)
+      assert_equal('Local test', Template.parse("{{'test' | notice }}").render!({}, filters: [local]))
     end
   end
 
   def test_has_key_will_not_add_an_error_for_missing_keys
-    with_error_mode :strict do
+    with_error_mode(:strict) do
       context = Context.new
       context.key?('unknown')
-      assert_empty context.errors
+      assert_empty(context.errors)
     end
   end
-end
+
+  private
+
+  def assert_no_object_allocations
+    unless RUBY_ENGINE == 'ruby'
+      skip("stackprof needed to count object allocations")
+    end
+    require 'stackprof'
+
+    profile = StackProf.run(mode: :object) do
+      yield
+    end
+    assert_equal(0, profile[:samples])
+  end
+end # ContextTest

test/integration/document_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class DocumentTest < Minitest::Test
@@ -7,13 +9,13 @@ class DocumentTest < Minitest::Test
     exc = assert_raises(SyntaxError) do
       Template.parse("{% else %}")
     end
-    assert_equal exc.message, "Liquid syntax error: Unexpected outer 'else' tag"
+    assert_equal(exc.message, "Liquid syntax error: Unexpected outer 'else' tag")
   end
 
   def test_unknown_tag
     exc = assert_raises(SyntaxError) do
       Template.parse("{% foo %}")
     end
-    assert_equal exc.message, "Liquid syntax error: Unknown tag 'foo'"
+    assert_equal(exc.message, "Liquid syntax error: Unknown tag 'foo'")
   end
 end

test/integration/drop_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ContextDrop < Liquid::Drop
@@ -31,7 +33,7 @@ class ProductDrop < Liquid::Drop
 
   class CatchallDrop < Liquid::Drop
     def liquid_method_missing(method)
-      'catchall_method: ' << method.to_s
+      "catchall_method: #{method}"
     end
   end
 
@@ -47,10 +49,6 @@ class ProductDrop < Liquid::Drop
     ContextDrop.new
   end
 
-  def user_input
-    "foo".taint
-  end
-
   protected
 
   def callmenot
@@ -109,165 +107,151 @@ class DropsTest < Minitest::Test
 
   def test_product_drop
     tpl = Liquid::Template.parse('  ')
-    assert_equal '  ', tpl.render!('product' => ProductDrop.new)
-  end
-
-  def test_rendering_raises_on_tainted_attr
-    with_taint_mode(:error) do
-      tpl = Liquid::Template.parse('{{ product.user_input }}')
-      assert_raises TaintedError do
-        tpl.render!('product' => ProductDrop.new)
-      end
-    end
-  end
-
-  def test_rendering_warns_on_tainted_attr
-    with_taint_mode(:warn) do
-      tpl = Liquid::Template.parse('{{ product.user_input }}')
-      context = Context.new('product' => ProductDrop.new)
-      tpl.render!(context)
-      assert_equal [Liquid::TaintedError], context.warnings.map(&:class)
-      assert_equal "variable 'product.user_input' is tainted and was not escaped", context.warnings.first.to_s(false)
-    end
-  end
-
-  def test_rendering_doesnt_raise_on_escaped_tainted_attr
-    with_taint_mode(:error) do
-      tpl = Liquid::Template.parse('{{ product.user_input | escape }}')
-      tpl.render!('product' => ProductDrop.new)
-    end
+    assert_equal('  ', tpl.render!('product' => ProductDrop.new))
   end
 
   def test_drop_does_only_respond_to_whitelisted_methods
-    assert_equal "", Liquid::Template.parse("{{ product.inspect }}").render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse("{{ product.pretty_inspect }}").render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse("{{ product.whatever }}").render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse('{{ product | map: "inspect" }}').render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse('{{ product | map: "pretty_inspect" }}').render!('product' => ProductDrop.new)
-    assert_equal "", Liquid::Template.parse('{{ product | map: "whatever" }}').render!('product' => ProductDrop.new)
+    assert_equal("", Liquid::Template.parse("{{ product.inspect }}").render!('product' => ProductDrop.new))
+    assert_equal("", Liquid::Template.parse("{{ product.pretty_inspect }}").render!('product' => ProductDrop.new))
+    assert_equal("", Liquid::Template.parse("{{ product.whatever }}").render!('product' => ProductDrop.new))
+    assert_equal("", Liquid::Template.parse('{{ product | map: "inspect" }}').render!('product' => ProductDrop.new))
+    assert_equal("", Liquid::Template.parse('{{ product | map: "pretty_inspect" }}').render!('product' => ProductDrop.new))
+    assert_equal("", Liquid::Template.parse('{{ product | map: "whatever" }}').render!('product' => ProductDrop.new))
   end
 
   def test_drops_respond_to_to_liquid
-    assert_equal "text1", Liquid::Template.parse("{{ product.to_liquid.texts.text }}").render!('product' => ProductDrop.new)
-    assert_equal "text1", Liquid::Template.parse('{{ product | map: "to_liquid" | map: "texts" | map: "text" }}').render!('product' => ProductDrop.new)
+    assert_equal("text1", Liquid::Template.parse("{{ product.to_liquid.texts.text }}").render!('product' => ProductDrop.new))
+    assert_equal("text1", Liquid::Template.parse('{{ product | map: "to_liquid" | map: "texts" | map: "text" }}').render!('product' => ProductDrop.new))
   end
 
   def test_text_drop
     output = Liquid::Template.parse(' {{ product.texts.text }} ').render!('product' => ProductDrop.new)
-    assert_equal ' text1 ', output
+    assert_equal(' text1 ', output)
   end
 
   def test_catchall_unknown_method
     output = Liquid::Template.parse(' {{ product.catchall.unknown }} ').render!('product' => ProductDrop.new)
-    assert_equal ' catchall_method: unknown ', output
+    assert_equal(' catchall_method: unknown ', output)
   end
 
   def test_catchall_integer_argument_drop
     output = Liquid::Template.parse(' {{ product.catchall[8] }} ').render!('product' => ProductDrop.new)
-    assert_equal ' catchall_method: 8 ', output
+    assert_equal(' catchall_method: 8 ', output)
   end
 
   def test_text_array_drop
     output = Liquid::Template.parse('{% for text in product.texts.array %} {{text}} {% endfor %}').render!('product' => ProductDrop.new)
-    assert_equal ' text1  text2 ', output
+    assert_equal(' text1  text2 ', output)
   end
 
   def test_context_drop
     output = Liquid::Template.parse(' {{ context.bar }} ').render!('context' => ContextDrop.new, 'bar' => "carrot")
-    assert_equal ' carrot ', output
+    assert_equal(' carrot ', output)
+  end
+
+  def test_context_drop_array_with_map
+    output = Liquid::Template.parse(' {{ contexts | map: "bar" }} ').render!('contexts' => [ContextDrop.new, ContextDrop.new], 'bar' => "carrot")
+    assert_equal(' carrotcarrot ', output)
   end
 
   def test_nested_context_drop
     output = Liquid::Template.parse(' {{ product.context.foo }} ').render!('product' => ProductDrop.new, 'foo' => "monkey")
-    assert_equal ' monkey ', output
+    assert_equal(' monkey ', output)
   end
 
   def test_protected
     output = Liquid::Template.parse(' {{ product.callmenot }} ').render!('product' => ProductDrop.new)
-    assert_equal '  ', output
+    assert_equal('  ', output)
   end
 
   def test_object_methods_not_allowed
     [:dup, :clone, :singleton_class, :eval, :class_eval, :inspect].each do |method|
       output = Liquid::Template.parse(" {{ product.#{method} }} ").render!('product' => ProductDrop.new)
-      assert_equal '  ', output
+      assert_equal('  ', output)
     end
   end
 
   def test_scope
-    assert_equal '1', Liquid::Template.parse('{{ context.scopes }}').render!('context' => ContextDrop.new)
-    assert_equal '2', Liquid::Template.parse('{%for i in dummy%}{{ context.scopes }}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal '3', Liquid::Template.parse('{%for i in dummy%}{%for i in dummy%}{{ context.scopes }}{%endfor%}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal('1', Liquid::Template.parse('{{ context.scopes }}').render!('context' => ContextDrop.new))
+    assert_equal('2', Liquid::Template.parse('{%for i in dummy%}{{ context.scopes }}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1]))
+    assert_equal('3', Liquid::Template.parse('{%for i in dummy%}{%for i in dummy%}{{ context.scopes }}{%endfor%}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1]))
   end
 
   def test_scope_though_proc
-    assert_equal '1', Liquid::Template.parse('{{ s }}').render!('context' => ContextDrop.new, 's' => proc{ |c| c['context.scopes'] })
-    assert_equal '2', Liquid::Template.parse('{%for i in dummy%}{{ s }}{%endfor%}').render!('context' => ContextDrop.new, 's' => proc{ |c| c['context.scopes'] }, 'dummy' => [1])
-    assert_equal '3', Liquid::Template.parse('{%for i in dummy%}{%for i in dummy%}{{ s }}{%endfor%}{%endfor%}').render!('context' => ContextDrop.new, 's' => proc{ |c| c['context.scopes'] }, 'dummy' => [1])
+    assert_equal('1', Liquid::Template.parse('{{ s }}').render!('context' => ContextDrop.new, 's' => proc { |c| c['context.scopes'] }))
+    assert_equal('2', Liquid::Template.parse('{%for i in dummy%}{{ s }}{%endfor%}').render!('context' => ContextDrop.new, 's' => proc { |c| c['context.scopes'] }, 'dummy' => [1]))
+    assert_equal('3', Liquid::Template.parse('{%for i in dummy%}{%for i in dummy%}{{ s }}{%endfor%}{%endfor%}').render!('context' => ContextDrop.new, 's' => proc { |c| c['context.scopes'] }, 'dummy' => [1]))
   end
 
   def test_scope_with_assigns
-    assert_equal 'variable', Liquid::Template.parse('{% assign a = "variable"%}{{a}}').render!('context' => ContextDrop.new)
-    assert_equal 'variable', Liquid::Template.parse('{% assign a = "variable"%}{%for i in dummy%}{{a}}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal 'test', Liquid::Template.parse('{% assign header_gif = "test"%}{{header_gif}}').render!('context' => ContextDrop.new)
-    assert_equal 'test', Liquid::Template.parse("{% assign header_gif = 'test'%}{{header_gif}}").render!('context' => ContextDrop.new)
+    assert_equal('variable', Liquid::Template.parse('{% assign a = "variable"%}{{a}}').render!('context' => ContextDrop.new))
+    assert_equal('variable', Liquid::Template.parse('{% assign a = "variable"%}{%for i in dummy%}{{a}}{%endfor%}').render!('context' => ContextDrop.new, 'dummy' => [1]))
+    assert_equal('test', Liquid::Template.parse('{% assign header_gif = "test"%}{{header_gif}}').render!('context' => ContextDrop.new))
+    assert_equal('test', Liquid::Template.parse("{% assign header_gif = 'test'%}{{header_gif}}").render!('context' => ContextDrop.new))
   end
 
   def test_scope_from_tags
-    assert_equal '1', Liquid::Template.parse('{% for i in context.scopes_as_array %}{{i}}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal '12', Liquid::Template.parse('{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1])
-    assert_equal '123', Liquid::Template.parse('{%for a in dummy%}{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1])
+    assert_equal('1', Liquid::Template.parse('{% for i in context.scopes_as_array %}{{i}}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1]))
+    assert_equal('12', Liquid::Template.parse('{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1]))
+    assert_equal('123', Liquid::Template.parse('{%for a in dummy%}{%for a in dummy%}{% for i in context.scopes_as_array %}{{i}}{% endfor %}{% endfor %}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1]))
   end
 
   def test_access_context_from_drop
-    assert_equal '123', Liquid::Template.parse('{%for a in dummy%}{{ context.loop_pos }}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1, 2, 3])
+    assert_equal('123', Liquid::Template.parse('{%for a in dummy%}{{ context.loop_pos }}{% endfor %}').render!('context' => ContextDrop.new, 'dummy' => [1, 2, 3]))
   end
 
   def test_enumerable_drop
-    assert_equal '123', Liquid::Template.parse('{% for c in collection %}{{c}}{% endfor %}').render!('collection' => EnumerableDrop.new)
+    assert_equal('123', Liquid::Template.parse('{% for c in collection %}{{c}}{% endfor %}').render!('collection' => EnumerableDrop.new))
   end
 
   def test_enumerable_drop_size
-    assert_equal '3', Liquid::Template.parse('{{collection.size}}').render!('collection' => EnumerableDrop.new)
+    assert_equal('3', Liquid::Template.parse('{{collection.size}}').render!('collection' => EnumerableDrop.new))
   end
 
   def test_enumerable_drop_will_invoke_liquid_method_missing_for_clashing_method_names
     ["select", "each", "map", "cycle"].each do |method|
-      assert_equal method.to_s, Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
-      assert_equal method.to_s, Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
-      assert_equal method.to_s, Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal method.to_s, Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new)
+      assert_equal(method.to_s, Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new))
+      assert_equal(method.to_s, Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new))
+      assert_equal(method.to_s, Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new))
+      assert_equal(method.to_s, Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new))
     end
   end
 
   def test_some_enumerable_methods_still_get_invoked
-    [ :count, :max ].each do |method|
-      assert_equal "3", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "3", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "3", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
-      assert_equal "3", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
+    [:count, :max].each do |method|
+      assert_equal("3", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new))
+      assert_equal("3", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new))
+      assert_equal("3", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new))
+      assert_equal("3", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new))
     end
 
-    assert_equal "yes", Liquid::Template.parse("{% if collection contains 3 %}yes{% endif %}").render!('collection' => RealEnumerableDrop.new)
+    assert_equal("yes", Liquid::Template.parse("{% if collection contains 3 %}yes{% endif %}").render!('collection' => RealEnumerableDrop.new))
 
-    [ :min, :first ].each do |method|
-      assert_equal "1", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "1", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new)
-      assert_equal "1", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new)
-      assert_equal "1", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new)
+    [:min, :first].each do |method|
+      assert_equal("1", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => RealEnumerableDrop.new))
+      assert_equal("1", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => RealEnumerableDrop.new))
+      assert_equal("1", Liquid::Template.parse("{{collection.#{method}}}").render!('collection' => EnumerableDrop.new))
+      assert_equal("1", Liquid::Template.parse("{{collection[\"#{method}\"]}}").render!('collection' => EnumerableDrop.new))
     end
   end
 
   def test_empty_string_value_access
-    assert_equal '', Liquid::Template.parse('{{ product[value] }}').render!('product' => ProductDrop.new, 'value' => '')
+    assert_equal('', Liquid::Template.parse('{{ product[value] }}').render!('product' => ProductDrop.new, 'value' => ''))
   end
 
   def test_nil_value_access
-    assert_equal '', Liquid::Template.parse('{{ product[value] }}').render!('product' => ProductDrop.new, 'value' => nil)
+    assert_equal('', Liquid::Template.parse('{{ product[value] }}').render!('product' => ProductDrop.new, 'value' => nil))
   end
 
   def test_default_to_s_on_drops
-    assert_equal 'ProductDrop', Liquid::Template.parse("{{ product }}").render!('product' => ProductDrop.new)
-    assert_equal 'EnumerableDrop', Liquid::Template.parse('{{ collection }}').render!('collection' => EnumerableDrop.new)
+    assert_equal('ProductDrop', Liquid::Template.parse("{{ product }}").render!('product' => ProductDrop.new))
+    assert_equal('EnumerableDrop', Liquid::Template.parse('{{ collection }}').render!('collection' => EnumerableDrop.new))
+  end
+
+  def test_invokable_methods
+    assert_equal(%w(to_liquid catchall context texts).to_set, ProductDrop.invokable_methods)
+    assert_equal(%w(to_liquid scopes_as_array loop_pos scopes).to_set, ContextDrop.invokable_methods)
+    assert_equal(%w(to_liquid size max min first count).to_set, EnumerableDrop.invokable_methods)
+    assert_equal(%w(to_liquid max min sort count first).to_set, RealEnumerableDrop.invokable_methods)
   end
 end # DropsTest

test/integration/error_handling_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ErrorHandlingTest < Minitest::Test
@@ -33,31 +35,31 @@ class ErrorHandlingTest < Minitest::Test
     TEXT
 
     output = Liquid::Template.parse(template, line_numbers: true).render('errors' => ErrorDrop.new)
-    assert_equal expected, output
+    assert_equal(expected, output)
   end
 
   def test_standard_error
     template = Liquid::Template.parse(' {{ errors.standard_error }} ')
-    assert_equal ' Liquid error: standard error ', template.render('errors' => ErrorDrop.new)
+    assert_equal(' Liquid error: standard error ', template.render('errors' => ErrorDrop.new))
 
-    assert_equal 1, template.errors.size
-    assert_equal StandardError, template.errors.first.class
+    assert_equal(1, template.errors.size)
+    assert_equal(StandardError, template.errors.first.class)
   end
 
   def test_syntax
     template = Liquid::Template.parse(' {{ errors.syntax_error }} ')
-    assert_equal ' Liquid syntax error: syntax error ', template.render('errors' => ErrorDrop.new)
+    assert_equal(' Liquid syntax error: syntax error ', template.render('errors' => ErrorDrop.new))
 
-    assert_equal 1, template.errors.size
-    assert_equal SyntaxError, template.errors.first.class
+    assert_equal(1, template.errors.size)
+    assert_equal(SyntaxError, template.errors.first.class)
   end
 
   def test_argument
     template = Liquid::Template.parse(' {{ errors.argument_error }} ')
-    assert_equal ' Liquid error: argument error ', template.render('errors' => ErrorDrop.new)
+    assert_equal(' Liquid error: argument error ', template.render('errors' => ErrorDrop.new))
 
-    assert_equal 1, template.errors.size
-    assert_equal ArgumentError, template.errors.first.class
+    assert_equal(1, template.errors.size)
+    assert_equal(ArgumentError, template.errors.first.class)
   end
 
   def test_missing_endtag_parse_time_error
@@ -76,22 +78,21 @@ class ErrorHandlingTest < Minitest::Test
 
   def test_lax_unrecognized_operator
     template = Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', error_mode: :lax)
-    assert_equal ' Liquid error: Unknown operator =! ', template.render
-    assert_equal 1, template.errors.size
-    assert_equal Liquid::ArgumentError, template.errors.first.class
+    assert_equal(' Liquid error: Unknown operator =! ', template.render)
+    assert_equal(1, template.errors.size)
+    assert_equal(Liquid::ArgumentError, template.errors.first.class)
   end
 
   def test_with_line_numbers_adds_numbers_to_parser_errors
     err = assert_raises(SyntaxError) do
-      Liquid::Template.parse(%q(
+      Liquid::Template.parse('
           foobar
 
           {% "cat" | foobar %}
 
           bla
-        ),
-        line_numbers: true
-      )
+        ',
+        line_numbers: true)
     end
 
     assert_match(/Liquid syntax error \(line 4\)/, err.message)
@@ -99,15 +100,14 @@ class ErrorHandlingTest < Minitest::Test
 
   def test_with_line_numbers_adds_numbers_to_parser_errors_with_whitespace_trim
     err = assert_raises(SyntaxError) do
-      Liquid::Template.parse(%q(
+      Liquid::Template.parse('
           foobar
 
           {%- "cat" | foobar -%}
 
           bla
-        ),
-        line_numbers: true
-      )
+        ',
+        line_numbers: true)
     end
 
     assert_match(/Liquid syntax error \(line 4\)/, err.message)
@@ -122,11 +122,10 @@ class ErrorHandlingTest < Minitest::Test
         bla
             ',
       error_mode: :warn,
-      line_numbers: true
-                                     )
+      line_numbers: true)
 
-    assert_equal ['Liquid syntax error (line 4): Unexpected character = in "1 =! 2"'],
-      template.warnings.map(&:message)
+    assert_equal(['Liquid syntax error (line 4): Unexpected character = in "1 =! 2"'],
+      template.warnings.map(&:message))
   end
 
   def test_parsing_strict_with_line_numbers_adds_numbers_to_lexer_errors
@@ -139,11 +138,10 @@ class ErrorHandlingTest < Minitest::Test
           bla
                 ',
         error_mode: :strict,
-        line_numbers: true
-                            )
+        line_numbers: true)
     end
 
-    assert_equal 'Liquid syntax error (line 4): Unexpected character = in "1 =! 2"', err.message
+    assert_equal('Liquid syntax error (line 4): Unexpected character = in "1 =! 2"', err.message)
   end
 
   def test_syntax_errors_in_nested_blocks_have_correct_line_number
@@ -157,46 +155,45 @@ class ErrorHandlingTest < Minitest::Test
 
           bla
                 ',
-        line_numbers: true
-                            )
+        line_numbers: true)
     end
 
-    assert_equal "Liquid syntax error (line 5): Unknown tag 'foo'", err.message
+    assert_equal("Liquid syntax error (line 5): Unknown tag 'foo'", err.message)
   end
 
   def test_strict_error_messages
     err = assert_raises(SyntaxError) do
       Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ', error_mode: :strict)
     end
-    assert_equal 'Liquid syntax error: Unexpected character = in "1 =! 2"', err.message
+    assert_equal('Liquid syntax error: Unexpected character = in "1 =! 2"', err.message)
 
     err = assert_raises(SyntaxError) do
       Liquid::Template.parse('{{%%%}}', error_mode: :strict)
     end
-    assert_equal 'Liquid syntax error: Unexpected character % in "{{%%%}}"', err.message
+    assert_equal('Liquid syntax error: Unexpected character % in "{{%%%}}"', err.message)
   end
 
   def test_warnings
     template = Liquid::Template.parse('{% if ~~~ %}{{%%%}}{% else %}{{ hello. }}{% endif %}', error_mode: :warn)
-    assert_equal 3, template.warnings.size
-    assert_equal 'Unexpected character ~ in "~~~"', template.warnings[0].to_s(false)
-    assert_equal 'Unexpected character % in "{{%%%}}"', template.warnings[1].to_s(false)
-    assert_equal 'Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].to_s(false)
-    assert_equal '', template.render
+    assert_equal(3, template.warnings.size)
+    assert_equal('Unexpected character ~ in "~~~"', template.warnings[0].to_s(false))
+    assert_equal('Unexpected character % in "{{%%%}}"', template.warnings[1].to_s(false))
+    assert_equal('Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].to_s(false))
+    assert_equal('', template.render)
   end
 
   def test_warning_line_numbers
     template = Liquid::Template.parse("{% if ~~~ %}\n{{%%%}}{% else %}\n{{ hello. }}{% endif %}", error_mode: :warn, line_numbers: true)
-    assert_equal 'Liquid syntax error (line 1): Unexpected character ~ in "~~~"', template.warnings[0].message
-    assert_equal 'Liquid syntax error (line 2): Unexpected character % in "{{%%%}}"', template.warnings[1].message
-    assert_equal 'Liquid syntax error (line 3): Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].message
-    assert_equal 3, template.warnings.size
-    assert_equal [1, 2, 3], template.warnings.map(&:line_number)
+    assert_equal('Liquid syntax error (line 1): Unexpected character ~ in "~~~"', template.warnings[0].message)
+    assert_equal('Liquid syntax error (line 2): Unexpected character % in "{{%%%}}"', template.warnings[1].message)
+    assert_equal('Liquid syntax error (line 3): Expected id but found end_of_string in "{{ hello. }}"', template.warnings[2].message)
+    assert_equal(3, template.warnings.size)
+    assert_equal([1, 2, 3], template.warnings.map(&:line_number))
   end
 
   # Liquid should not catch Exceptions that are not subclasses of StandardError, like Interrupt and NoMemoryError
   def test_exceptions_propagate
-    assert_raises Exception do
+    assert_raises(Exception) do
       template = Liquid::Template.parse('{{ errors.exception }}')
       template.render('errors' => ErrorDrop.new)
     end
@@ -205,41 +202,47 @@ class ErrorHandlingTest < Minitest::Test
   def test_default_exception_renderer_with_internal_error
     template = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
 
-    output = template.render({ 'errors' => ErrorDrop.new })
+    output = template.render('errors' => ErrorDrop.new)
 
-    assert_equal 'This is a runtime error: Liquid error (line 1): internal', output
-    assert_equal [Liquid::InternalError], template.errors.map(&:class)
+    assert_equal('This is a runtime error: Liquid error (line 1): internal', output)
+    assert_equal([Liquid::InternalError], template.errors.map(&:class))
   end
 
   def test_setting_default_exception_renderer
     old_exception_renderer = Liquid::Template.default_exception_renderer
     exceptions = []
-    Liquid::Template.default_exception_renderer = ->(e) { exceptions << e; '' }
+    Liquid::Template.default_exception_renderer = ->(e) {
+      exceptions << e
+      ''
+    }
     template = Liquid::Template.parse('This is a runtime error: {{ errors.argument_error }}')
 
-    output = template.render({ 'errors' => ErrorDrop.new })
+    output = template.render('errors' => ErrorDrop.new)
 
-    assert_equal 'This is a runtime error: ', output
-    assert_equal [Liquid::ArgumentError], template.errors.map(&:class)
+    assert_equal('This is a runtime error: ', output)
+    assert_equal([Liquid::ArgumentError], template.errors.map(&:class))
   ensure
     Liquid::Template.default_exception_renderer = old_exception_renderer if old_exception_renderer
   end
 
   def test_exception_renderer_exposing_non_liquid_error
-    template = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
+    template   = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
     exceptions = []
-    handler = ->(e) { exceptions << e; e.cause }
+    handler    = ->(e) {
+      exceptions << e
+      e.cause
+    }
 
     output = template.render({ 'errors' => ErrorDrop.new }, exception_renderer: handler)
 
-    assert_equal 'This is a runtime error: runtime error', output
-    assert_equal [Liquid::InternalError], exceptions.map(&:class)
-    assert_equal exceptions, template.errors
-    assert_equal '#<RuntimeError: runtime error>', exceptions.first.cause.inspect
+    assert_equal('This is a runtime error: runtime error', output)
+    assert_equal([Liquid::InternalError], exceptions.map(&:class))
+    assert_equal(exceptions, template.errors)
+    assert_equal('#<RuntimeError: runtime error>', exceptions.first.cause.inspect)
   end
 
   class TestFileSystem
-    def read_template_file(template_path)
+    def read_template_file(_template_path)
       "{{ errors.argument_error }}"
     end
   end
@@ -249,12 +252,21 @@ class ErrorHandlingTest < Minitest::Test
 
     begin
       Liquid::Template.file_system = TestFileSystem.new
+
       template = Liquid::Template.parse("Argument error:\n{% include 'product' %}", line_numbers: true)
-      page = template.render('errors' => ErrorDrop.new)
+      page     = template.render('errors' => ErrorDrop.new)
     ensure
       Liquid::Template.file_system = old_file_system
     end
-    assert_equal "Argument error:\nLiquid error (product line 1): argument error", page
-    assert_equal "product", template.errors.first.template_name
+    assert_equal("Argument error:\nLiquid error (product line 1): argument error", page)
+    assert_equal("product", template.errors.first.template_name)
+  end
+
+  def test_bug_compatible_silencing_of_errors_in_blank_nodes
+    output = Liquid::Template.parse("{% assign x = 0 %}{% if 1 < '2' %}not blank{% assign x = 3 %}{% endif %}{{ x }}").render
+    assert_equal("Liquid error: comparison of Integer with String failed0", output)
+
+    output = Liquid::Template.parse("{% assign x = 0 %}{% if 1 < '2' %}{% assign x = 3 %}{% endif %}{{ x }}").render
+    assert_equal("0", output)
   end
 end

test/integration/expression_test.rb

@@ -0,0 +1,46 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ExpressionTest < Minitest::Test
+  def test_keyword_literals
+    assert_equal(true, parse_and_eval("true"))
+    assert_equal(true, parse_and_eval(" true "))
+  end
+
+  def test_string
+    assert_equal("single quoted", parse_and_eval("'single quoted'"))
+    assert_equal("double quoted", parse_and_eval('"double quoted"'))
+    assert_equal("spaced", parse_and_eval(" 'spaced' "))
+    assert_equal("spaced2", parse_and_eval(' "spaced2" '))
+  end
+
+  def test_int
+    assert_equal(123, parse_and_eval("123"))
+    assert_equal(456, parse_and_eval(" 456 "))
+    assert_equal(12, parse_and_eval("012"))
+  end
+
+  def test_float
+    assert_equal(1.5, parse_and_eval("1.5"))
+    assert_equal(2.5, parse_and_eval(" 2.5 "))
+  end
+
+  def test_range
+    assert_equal(1..2, parse_and_eval("(1..2)"))
+    assert_equal(3..4, parse_and_eval(" ( 3 .. 4 ) "))
+  end
+
+  private
+
+  def parse_and_eval(markup, **assigns)
+    if Liquid::Template.error_mode == :strict
+      p = Liquid::Parser.new(markup)
+      markup = p.expression
+      p.consume(:end_of_string)
+    end
+    expression = Liquid::Expression.parse(markup)
+    context = Liquid::Context.new(assigns)
+    context.evaluate(expression)
+  end
+end

test/integration/filter_kwarg_test.rb

@@ -0,0 +1,24 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class FilterKwargTest < Minitest::Test
+  module KwargFilter
+    def html_tag(_tag, attributes)
+      attributes
+        .map { |key, value| "#{key}='#{value}'" }
+        .join(' ')
+    end
+  end
+
+  include Liquid
+
+  def test_can_parse_data_kwargs
+    with_global_filter(KwargFilter) do
+      assert_equal(
+        "data-src='src' data-widths='100, 200'",
+        Template.parse("{{ 'img' | html_tag: data-src: 'src', data-widths: '100, 200' }}").render(nil, nil)
+      )
+    end
+  end
+end