Fix array handling shortcut in disable_tags

* Use `Regexp#match?` when `MatchData` is not used

* Add `TargetRubyVersion: 2.4` to RuboCop config

.rubocop.yml

@@ -1,5 +1,5 @@
 inherit_from:
-  - https://shopify.github.io/ruby-style-guide/rubocop.yml
+  - 'https://shopify.github.io/ruby-style-guide/rubocop.yml'
   - .rubocop_todo.yml
 
 require: rubocop-performance
@@ -8,9 +8,10 @@ Performance:
   Enabled: true
 
 AllCops:
+  TargetRubyVersion: 2.4
   Exclude:
     - 'vendor/bundle/**/*'
-      
+
 Naming/MethodName:
   Exclude:
-    - 'example/server/liquid_servlet.rb'
+    - 'example/server/liquid_servlet.rb'

.rubocop_todo.yml

@@ -6,26 +6,6 @@
 # Note that changes in the inspected code, or installation of new
 # versions of RuboCop, may require this file to be generated again.
 
-# Offense count: 2
-Lint/AmbiguousOperator:
-  Exclude:
-    - 'test/unit/condition_unit_test.rb'
-
-# Offense count: 21
-# Configuration parameters: AllowSafeAssignment.
-Lint/AssignmentInCondition:
-  Exclude:
-    - 'lib/liquid/block_body.rb'
-    - 'lib/liquid/lexer.rb'
-    - 'lib/liquid/standardfilters.rb'
-    - 'lib/liquid/tags/for.rb'
-    - 'lib/liquid/tags/if.rb'
-    - 'lib/liquid/tags/raw.rb'
-    - 'lib/liquid/variable.rb'
-    - 'performance/profile.rb'
-    - 'test/test_helper.rb'
-    - 'test/unit/tokenizer_unit_test.rb'
-
 # Offense count: 2
 # Cop supports --auto-correct.
 # Configuration parameters: EnforcedStyle.
@@ -34,17 +14,6 @@ Lint/InheritException:
   Exclude:
     - 'lib/liquid/interrupts.rb'
 
-# Offense count: 2
-Lint/UselessAssignment:
-  Exclude:
-    - 'performance/shopify/database.rb'
-
-# Offense count: 1
-# Configuration parameters: CheckForMethodsWithNoSideEffects.
-Lint/Void:
-  Exclude:
-    - 'lib/liquid/parse_context.rb'
-
 # Offense count: 98
 # Cop supports --auto-correct.
 # Configuration parameters: AutoCorrect, AllowHeredoc, AllowURI, URISchemes, IgnoreCopDirectives, IgnoredPatterns.
@@ -76,26 +45,4 @@ Style/ClassVars:
   Exclude:
     - 'lib/liquid/condition.rb'
     - 'lib/liquid/strainer.rb'
-    - 'lib/liquid/template.rb'
-
-# Offense count: 1
-# Configuration parameters: AllowCoercion.
-Style/DateTime:
-  Exclude:
-    - 'test/unit/context_unit_test.rb'
-
-# Offense count: 119
-# Cop supports --auto-correct.
-# Configuration parameters: EnforcedStyle.
-# SupportedStyles: always, never
-Style/FrozenStringLiteralComment:
-  Enabled: false
-
-# Offense count: 9
-# Cop supports --auto-correct.
-# Configuration parameters: AllowAsExpressionSeparator.
-Style/Semicolon:
-  Exclude:
-    - 'test/integration/error_handling_test.rb'
-    - 'test/integration/template_test.rb'
-    - 'test/unit/context_unit_test.rb'
+    - 'lib/liquid/template.rb'

.travis.yml

@@ -7,8 +7,6 @@ rvm:
   - &latest_ruby 2.6
   - 2.7
   - ruby-head
-  - jruby-head
-  - truffleruby
 
 matrix:
   include:
@@ -17,8 +15,6 @@ matrix:
       name: Profiling Memory Usage
   allow_failures:
     - rvm: ruby-head
-    - rvm: jruby-head
-    - rvm: truffleruby
 
 branches:
   only:

Gemfile

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 source 'https://rubygems.org'
 git_source(:github) do |repo_name|
   "https://github.com/#{repo_name}.git"
@@ -20,6 +22,6 @@ group :test do
   gem 'rubocop-performance', require: false
 
   platform :mri, :truffleruby do
-    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'liquid-tag'
+    gem 'liquid-c', github: 'Shopify/liquid-c', ref: 'master'
   end
 end

README.md

@@ -106,3 +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

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'rake'
 require 'rake/testtask'
 $LOAD_PATH.unshift(File.expand_path("../lib", __FILE__))

example/server/example_servlet.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module ProductsFilter
   def price(integer)
     format("$%.2d USD", integer / 100.0)

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)

example/server/server.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'webrick'
 require 'rexml/document'
 

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\-\.\[\]]\)?/
@@ -75,7 +77,11 @@ require 'liquid/utils'
 require 'liquid/tokenizer'
 require 'liquid/parse_context'
 require 'liquid/partial_cache'
+require 'liquid/usage'
+require 'liquid/register'
+require 'liquid/static_registers'
 
 # Load all the tags of the standard library
 #
 Dir["#{__dir__}/liquid/tags/*.rb"].each { |f| require f }
+Dir["#{__dir__}/liquid/registers/*.rb"].each { |f| require f }

lib/liquid/block.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Block < Tag
     MAX_DEPTH = 100
@@ -27,16 +29,16 @@ module Liquid
     end
 
     def unknown_tag(tag, _params, _tokens)
-      if tag == 'else'.freeze
-        raise SyntaxError, parse_context.locale.t("errors.syntax.unexpected_else".freeze,
+      if tag == 'else'
+        raise SyntaxError, parse_context.locale.t("errors.syntax.unexpected_else",
           block_name: block_name)
-      elsif tag.start_with?('end'.freeze)
-        raise SyntaxError, parse_context.locale.t("errors.syntax.invalid_delimiter".freeze,
+      elsif tag.start_with?('end')
+        raise SyntaxError, parse_context.locale.t("errors.syntax.invalid_delimiter",
           tag: tag,
           block_name: block_name,
           block_delimiter: block_delimiter)
       else
-        raise SyntaxError, 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
 
@@ -52,7 +54,7 @@ module Liquid
 
     def parse_body(body, tokens)
       if parse_context.depth >= MAX_DEPTH
-        raise StackLevelError, "Nesting too deep".freeze
+        raise StackLevelError, "Nesting too deep"
       end
       parse_context.depth += 1
       begin
@@ -61,7 +63,7 @@ module Liquid
 
           return false if end_tag_name == block_delimiter
           unless end_tag_name
-            raise SyntaxError, parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name)
+            raise SyntaxError, parse_context.locale.t("errors.syntax.tag_never_closed", block_name: block_name)
           end
 
           # this tag is not registered with the system

lib/liquid/block_body.rb

@@ -1,11 +1,13 @@
+# frozen_string_literal: true
+
 module Liquid
   class BlockBody
     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 = "{%".freeze
-    VARSTART = "{{".freeze
+    TAGSTART = "{%"
+    VARSTART = "{{"
 
     attr_reader :nodelist
 
@@ -25,7 +27,7 @@ module Liquid
     end
 
     private def parse_for_liquid_tag(tokenizer, parse_context)
-      while token = tokenizer.shift
+      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
@@ -34,7 +36,7 @@ module Liquid
           end
           tag_name = Regexp.last_match(1)
           markup = Regexp.last_match(2)
-          unless tag = registered_tags[tag_name]
+          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
@@ -50,7 +52,7 @@ module Liquid
     end
 
     private def parse_for_document(tokenizer, parse_context, &block)
-      while token = tokenizer.shift
+      while (token = tokenizer.shift)
         next if token.empty?
         case
         when token.start_with?(TAGSTART)
@@ -64,15 +66,15 @@ module Liquid
           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".freeze) + Regexp.last_match(3).count("\n".freeze)
+            parse_context.line_number += Regexp.last_match(1).count("\n") + Regexp.last_match(3).count("\n")
           end
 
-          if tag_name == 'liquid'.freeze
+          if tag_name == 'liquid'
             liquid_tag_tokenizer = Tokenizer.new(markup, line_number: parse_context.line_number, for_liquid_tag: true)
             next parse_for_liquid_tag(liquid_tag_tokenizer, parse_context, &block)
           end
 
-          unless tag = registered_tags[tag_name]
+          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
@@ -113,14 +115,14 @@ module Liquid
     end
 
     def render(context)
-      render_to_output_buffer(context, '')
+      render_to_output_buffer(context, +'')
     end
 
     def render_to_output_buffer(context, output)
       context.resource_limits.render_score += @nodelist.length
 
       idx = 0
-      while node = @nodelist[idx]
+      while (node = @nodelist[idx])
         previous_output_size = output.bytesize
 
         case node
@@ -129,7 +131,7 @@ module Liquid
         when Variable
           render_node(context, output, node)
         when Block
-          render_node(context, node.blank? ? '' : output, node)
+          render_node(context, node.blank? ? +'' : output, node)
           break if context.interrupt? # might have happened in a for-block
         when Continue, Break
           # If we get an Interrupt that means the block must stop processing. An
@@ -152,7 +154,13 @@ module Liquid
     private
 
     def render_node(context, output, node)
-      node.render_to_output_buffer(context, output)
+      if node.disabled?(context)
+        output << node.disabled_error_message
+        return
+      end
+      disable_tags(context, node.disabled_tags) do
+        node.render_to_output_buffer(context, output)
+      end
     rescue UndefinedVariable, UndefinedDropMethod, UndefinedFilter => e
       context.handle_error(e, node.line_number)
     rescue ::StandardError => e
@@ -160,10 +168,15 @@ module Liquid
       output << context.handle_error(e, line_number)
     end
 
+    def disable_tags(context, tags, &block)
+      return yield if tags.empty?
+      context.registers['disabled_tags'].disable(tags, &block)
+    end
+
     def raise_if_resource_limits_reached(context, length)
       context.resource_limits.render_length += length
       return unless context.resource_limits.reached?
-      raise MemoryError, "Memory limits exceeded".freeze
+      raise MemoryError, "Memory limits exceeded"
     end
 
     def create_variable(token, parse_context)
@@ -175,11 +188,11 @@ module Liquid
     end
 
     def raise_missing_tag_terminator(token, parse_context)
-      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_termination".freeze, token: token, tag_end: TagEnd.inspect)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_termination", token: token, tag_end: TagEnd.inspect)
     end
 
     def raise_missing_variable_terminator(token, parse_context)
-      raise SyntaxError, parse_context.locale.t("errors.syntax.variable_termination".freeze, token: token, tag_end: VariableEnd.inspect)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.variable_termination", token: token, tag_end: VariableEnd.inspect)
     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
   #
@@ -8,14 +10,14 @@ module Liquid
   #
   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)
@@ -78,7 +80,7 @@ module Liquid
     end
 
     def inspect
-      "#<Condition #{[@left, @operator, @right].compact.join(' '.freeze)}>"
+      "#<Condition #{[@left, @operator, @right].compact.join(' ')}>"
     end
 
     protected

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
   #
@@ -16,18 +18,17 @@ module Liquid
     attr_accessor :exception_renderer, :template_name, :partial, :global_filter, :strict_variables, :strict_filters
 
     # rubocop:disable Metrics/ParameterLists
-    def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_registers: {}, static_environments: {})
-      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_registers, static_environments)
+    def self.build(environments: {}, outer_scope: {}, registers: {}, rethrow_errors: false, resource_limits: nil, static_environments: {})
+      new(environments, outer_scope, registers, rethrow_errors, resource_limits, static_environments)
     end
 
-    def initialize(environments = {}, outer_scope = {}, registers = {}, rethrow_errors = false, resource_limits = nil, static_registers = {}, static_environments = {})
+    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
-      @static_registers    = static_registers.freeze
       @errors              = []
       @partial             = false
       @strict_variables    = false
@@ -35,8 +36,6 @@ module Liquid
       @base_scope_depth    = 0
       squash_instance_assigns_with_environments
 
-      @this_stack_used = false
-
       self.exception_renderer = Template.default_exception_renderer
       if rethrow_errors
         self.exception_renderer = ->(_e) { raise }
@@ -122,19 +121,11 @@ module Liquid
     #   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
-
+    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.,
@@ -145,7 +136,7 @@ module Liquid
       Context.build(
         resource_limits: resource_limits,
         static_environments: static_environments,
-        static_registers: static_registers
+        registers: StaticRegisters.new(registers)
       ).tap do |subcontext|
         subcontext.base_scope_depth = base_scope_depth + 1
         subcontext.exception_renderer = exception_renderer
@@ -162,10 +153,6 @@ 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
 
@@ -246,7 +233,7 @@ module Liquid
     end
 
     def check_overflow
-      raise StackLevelError, "Nesting too deep".freeze if overflow?
+      raise StackLevelError, "Nesting too deep" if overflow?
     end
 
     def overflow?

lib/liquid/document.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Document < BlockBody
     def self.parse(tokens, parse_context)
@@ -17,10 +19,10 @@ module Liquid
 
     def unknown_tag(tag, parse_context)
       case tag
-      when 'else'.freeze, 'end'.freeze
-        raise SyntaxError, 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, 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
   end

lib/liquid/drop.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'set'
 
 module Liquid
@@ -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()
 
@@ -20,7 +22,7 @@ module Liquid
     private
 
     def message_prefix
-      str = ""
+      str = +""
       str << if is_a?(SyntaxError)
         "Liquid syntax error"
       else

lib/liquid/expression.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Expression
     class MethodLiteral
@@ -14,11 +16,11 @@ module Liquid
     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' => MethodLiteral.new(:blank?, '').freeze,
+      'empty' => MethodLiteral.new(:empty?, '').freeze
     }.freeze
 
     SINGLE_QUOTED_STRING = /\A'(.*)'\z/m

lib/liquid/extensions.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'time'
 require 'date'
 

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.
   #
@@ -44,7 +46,7 @@ module Liquid
   class LocalFileSystem
     attr_accessor :root
 
-    def initialize(root, pattern = "_%s.liquid".freeze)
+    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 =~ %r{\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

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class ForloopDrop < Drop
     def initialize(name, length, parentloop)

lib/liquid/i18n.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'yaml'
 
 module Liquid
@@ -31,7 +33,7 @@ module Liquid
     end
 
     def deep_fetch_translation(name)
-      name.split('.'.freeze).reduce(locale) do |level, cur|
+      name.split('.').reduce(locale) do |level, cur|
         level[cur] || raise(TranslationError, "Translation for #{name} does not exist in locale #{path}")
       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

@@ -1,17 +1,19 @@
+# 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,
+      '|' => :pipe,
+      '.' => :dot,
+      ':' => :colon,
+      ',' => :comma,
+      '[' => :open_square,
+      ']' => :close_square,
+      '(' => :open_round,
+      ')' => :close_round,
+      '?' => :question,
+      '-' => :dash,
     }.freeze
     IDENTIFIER = /[a-zA-Z_][\w-]*\??/
     SINGLE_STRING_LITERAL = /'[^\']*'/
@@ -31,15 +33,21 @@ module Liquid
       until @ss.eos?
         @ss.skip(WHITESPACE_OR_NOTHING)
         break if @ss.eos?
-        tok = if t = @ss.scan(COMPARISON_OPERATOR) then [:comparison, t]
-        elsif t = @ss.scan(SINGLE_STRING_LITERAL) then [:string, t]
-        elsif t = @ss.scan(DOUBLE_STRING_LITERAL) then [:string, t]
-        elsif t = @ss.scan(NUMBER_LITERAL) then [:number, t]
-        elsif t = @ss.scan(IDENTIFIER) then [:id, t]
-        elsif t = @ss.scan(DOTDOT) then [:dotdot, t]
+        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]
+          if (s = SPECIALS[c])
             [s, c]
           else
             raise SyntaxError, "Unexpected character #{c}"

lib/liquid/locales/en.yml

@@ -25,3 +25,5 @@
       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

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class ParseContext
     attr_accessor :locale, :line_number, :trim_whitespace, :depth
@@ -19,7 +21,6 @@ module Liquid
       @partial = value
       @options = value ? partial_options : @template_options
       @error_mode = @options[:error_mode] || Template.error_mode
-      value
     end
 
     def partial_options

lib/liquid/parser.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Parser
     def initialize(input)
@@ -66,10 +68,10 @@ 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

lib/liquid/parser_switching.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   module ParserSwitching
     def parse_with_selected_parser(markup)

lib/liquid/partial_cache.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class PartialCache
     def self.load(template_name, context:, parse_context:)

lib/liquid/profiler.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'liquid/profiler/hooks'
 
 module Liquid

lib/liquid/profiler/hooks.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class BlockBody
     def render_node_with_profiling(context, output, node)

lib/liquid/range_lookup.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class RangeLookup
     def self.parse(start_markup, end_markup)

lib/liquid/register.rb

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

lib/liquid/registers/disabled_tags.rb

@@ -0,0 +1,32 @@
+# frozen_string_literal: true
+module Liquid
+  class DisabledTags < Register
+    def initialize
+      @disabled_tags = {}
+    end
+
+    def disabled?(tag)
+      @disabled_tags.key?(tag) && @disabled_tags[tag] > 0
+    end
+
+    def disable(tags)
+      tags.each(&method(:increment))
+      yield
+    ensure
+      tags.each(&method(:decrement))
+    end
+
+    private
+
+    def increment(tag)
+      @disabled_tags[tag] ||= 0
+      @disabled_tags[tag] += 1
+    end
+
+    def decrement(tag)
+      @disabled_tags[tag] -= 1
+    end
+  end
+
+  Template.add_register('disabled_tags', DisabledTags.new)
+end

lib/liquid/resource_limits.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class ResourceLimits
     attr_accessor :render_length, :render_score, :assign_score,

lib/liquid/standardfilters.rb

@@ -1,14 +1,16 @@
+# frozen_string_literal: true
+
 require 'cgi'
 require 'bigdecimal'
 
 module Liquid
   module StandardFilters
     HTML_ESCAPE = {
-      '&'.freeze => '&'.freeze,
-      '>'.freeze => '>'.freeze,
-      '<'.freeze => '&lt;'.freeze,
-      '"'.freeze => '&quot;'.freeze,
-      "'".freeze => '&#39;'.freeze,
+      '&' => '&amp;',
+      '>' => '&gt;',
+      '<' => '&lt;',
+      '"' => '&quot;',
+      "'" => '&#39;',
     }.freeze
     HTML_ESCAPE_ONCE_REGEXP = /["><']|&(?!([a-zA-Z]+|(#\d+));)/
     STRIP_HTML_BLOCKS = Regexp.union(
@@ -72,7 +74,7 @@ module Liquid
     end
 
     # Truncate a string down to x characters
-    def truncate(input, length = 50, truncate_string = "...".freeze)
+    def truncate(input, length = 50, truncate_string = "...")
       return if input.nil?
       input_str = input.to_s
       length = Utils.to_integer(length)
@@ -82,13 +84,13 @@ module Liquid
       input_str.length > length ? input_str[0...l].concat(truncate_string_str) : input_str
     end
 
-    def truncatewords(input, words = 15, truncate_string = "...".freeze)
+    def truncatewords(input, words = 15, truncate_string = "...")
       return if input.nil?
       wordlist = input.to_s.split
       words = Utils.to_integer(words)
       l = words - 1
       l = 0 if l < 0
-      wordlist.length > l ? wordlist[0..l].join(" ".freeze).concat(truncate_string.to_s) : input
+      wordlist.length > l ? wordlist[0..l].join(" ").concat(truncate_string.to_s) : input
     end
 
     # Split input string into an array of substrings separated by given pattern.
@@ -113,7 +115,7 @@ module Liquid
     end
 
     def strip_html(input)
-      empty = ''.freeze
+      empty = ''
       result = input.to_s.gsub(STRIP_HTML_BLOCKS, empty)
       result.gsub!(STRIP_HTML_TAGS, empty)
       result
@@ -121,11 +123,11 @@ module Liquid
 
     # Remove all newlines from the string
     def strip_newlines(input)
-      input.to_s.gsub(/\r?\n/, ''.freeze)
+      input.to_s.gsub(/\r?\n/, '')
     end
 
     # Join elements of the array with certain character between them
-    def join(input, glue = ' '.freeze)
+    def join(input, glue = ' ')
       InputIterator.new(input).join(glue)
     end
 
@@ -220,7 +222,7 @@ module Liquid
       InputIterator.new(input).map do |e|
         e = e.call if e.is_a?(Proc)
 
-        if property == "to_liquid".freeze
+        if property == "to_liquid"
           e
         elsif e.respond_to?(:[])
           r = e[property]
@@ -250,23 +252,23 @@ module Liquid
     end
 
     # Replace occurrences of a string with another
-    def replace(input, string, replacement = ''.freeze)
+    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)
+      input.to_s.gsub(string.to_s, '')
     end
 
     # remove the first occurrences of a substring
     def remove_first(input, string)
-      input.to_s.sub(string.to_s, ''.freeze)
+      input.to_s.sub(string.to_s, '')
     end
 
     # add one string to another
@@ -288,7 +290,7 @@ module Liquid
 
     # Add <br /> tags in front of all newlines in input string
     def newline_to_br(input)
-      input.to_s.gsub(/\n/, "<br />\n".freeze)
+      input.to_s.gsub(/\n/, "<br />\n")
     end
 
     # Reformat a date using Ruby's core Time#strftime( string ) -> string
@@ -325,7 +327,7 @@ 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
@@ -419,8 +421,9 @@ module Liquid
       result.is_a?(BigDecimal) ? result.to_f : result
     end
 
-    def default(input, default_value = ''.freeze)
+    def default(input, default_value = '')
       if !input || input.respond_to?(:empty?) && input.empty?
+        Usage.increment("default_filter_received_false_value") if input == false # See https://github.com/Shopify/liquid/issues/1127
         default_value
       else
         input

lib/liquid/static_registers.rb

@@ -0,0 +1,36 @@
+# frozen_string_literal: true
+
+module Liquid
+  class StaticRegisters
+    attr_reader :static, :registers
+
+    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
+
+    def fetch(key, default = nil)
+      key?(key) ? self[key] : default
+    end
+
+    def key?(key)
+      @registers.key?(key) || @static.key?(key)
+    end
+  end
+end

lib/liquid/strainer.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'set'
 
 module Liquid

lib/liquid/tablerowloop_drop.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class TablerowloopDrop < Drop
     def initialize(length, cols)

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
@@ -11,7 +13,15 @@ module Liquid
         tag
       end
 
+      def disable_tags(*tags)
+        disabled_tags.push(*tags)
+      end
+
       private :new
+
+      def disabled_tags
+        @disabled_tags ||= []
+      end
     end
 
     def initialize(tag_name, markup, parse_context)
@@ -33,7 +43,15 @@ module Liquid
     end
 
     def render(_context)
-      ''.freeze
+      ''
+    end
+
+    def disabled?(context)
+      context.registers['disabled_tags'].disabled?(tag_name)
+    end
+
+    def disabled_error_message
+      "#{tag_name} #{options[:locale].t('errors.disabled.tag')}"
     end
 
     # For backwards compatibility with custom tags. In a future release, the semantics
@@ -47,5 +65,9 @@ module Liquid
     def blank?
       false
     end
+
+    def disabled_tags
+      self.class.disabled_tags
+    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.
   #
@@ -11,7 +13,7 @@ module Liquid
     Syntax = /(#{VariableSignature}+)\s*=\s*(.*)\s*/om
 
     def self.syntax_error_translation_key
-      "errors.syntax.assign".freeze
+      "errors.syntax.assign"
     end
 
     attr_reader :to, :from
@@ -59,5 +61,5 @@ module Liquid
     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.
   #
@@ -14,5 +16,5 @@ module Liquid
     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.
   #
@@ -35,5 +37,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('capture'.freeze, Capture)
+  Template.register_tag('capture', Capture)
 end

lib/liquid/tags/case.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Case < Block
     Syntax     = /(#{QuotedFragment})/o
@@ -12,7 +14,7 @@ module Liquid
       if markup =~ Syntax
         @left = Expression.parse(Regexp.last_match(1))
       else
-        raise SyntaxError, options[:locale].t("errors.syntax.case".freeze)
+        raise SyntaxError, options[:locale].t("errors.syntax.case")
       end
     end
 
@@ -27,9 +29,9 @@ 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
@@ -37,16 +39,14 @@ module Liquid
     end
 
     def render_to_output_buffer(context, output)
-      context.stack do
-        execute_else_block = true
+      execute_else_block = true
 
-        @blocks.each do |block|
-          if block.else?
-            block.attachment.render_to_output_buffer(context, output) if execute_else_block
-          elsif block.evaluate(context)
-            execute_else_block = false
-            block.attachment.render_to_output_buffer(context, output)
-          end
+      @blocks.each do |block|
+        if block.else?
+          block.attachment.render_to_output_buffer(context, output) if execute_else_block
+        elsif block.evaluate(context)
+          execute_else_block = false
+          block.attachment.render_to_output_buffer(context, output)
         end
       end
 
@@ -60,12 +60,12 @@ module Liquid
 
       while markup
         unless markup =~ WhenSyntax
-          raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_when".freeze)
+          raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_when")
         end
 
         markup = Regexp.last_match(2)
 
-        block = Condition.new(@left, '=='.freeze, Expression.parse(Regexp.last_match(1)))
+        block = Condition.new(@left, '==', Expression.parse(Regexp.last_match(1)))
         block.attach(body)
         @blocks << block
       end
@@ -73,7 +73,7 @@ module Liquid
 
     def record_else_condition(markup)
       unless markup.strip.empty?
-        raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_else".freeze)
+        raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_else")
       end
 
       block = ElseCondition.new
@@ -88,5 +88,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('case'.freeze, Case)
+  Template.register_tag('case', Case)
 end

lib/liquid/tags/comment.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Comment < Block
     def render_to_output_buffer(_context, output)
@@ -12,5 +14,5 @@ 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.
   #
@@ -14,5 +16,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('continue'.freeze, Continue)
+  Template.register_tag('continue', Continue)
 end

lib/liquid/tags/cycle.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Cycle is usually used within a loop to alternate between values, like colors or DOM classes.
   #
@@ -27,32 +29,30 @@ module Liquid
         @variables = variables_from_string(markup)
         @name = @variables.to_s
       else
-        raise SyntaxError, options[:locale].t("errors.syntax.cycle".freeze)
+        raise SyntaxError, options[:locale].t("errors.syntax.cycle")
       end
     end
 
     def render_to_output_buffer(context, output)
       context.registers[:cycle] ||= {}
 
-      context.stack do
-        key = context.evaluate(@name)
-        iteration = context.registers[:cycle][key].to_i
+      key = context.evaluate(@name)
+      iteration = context.registers[:cycle][key].to_i
 
-        val = context.evaluate(@variables[iteration])
+      val = context.evaluate(@variables[iteration])
 
-        if val.is_a?(Array)
-          val = val.join
-        elsif !val.is_a?(String)
-          val = val.to_s
-        end
-
-        output << val
-
-        iteration += 1
-        iteration  = 0 if iteration >= @variables.size
-        context.registers[:cycle][key] = iteration
+      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
 

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
@@ -32,5 +34,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('decrement'.freeze, Decrement)
+  Template.register_tag('decrement', Decrement)
 end

lib/liquid/tags/echo.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # Echo outputs an expression
   #
@@ -16,9 +18,9 @@ module Liquid
     end
 
     def render(context)
-      @variable.render_to_output_buffer(context, '')
+      @variable.render_to_output_buffer(context, +'')
     end
   end
 
-  Template.register_tag('echo'.freeze, Echo)
+  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.
@@ -66,7 +68,7 @@ module Liquid
     end
 
     def unknown_tag(tag, markup, tokens)
-      return super unless tag == 'else'.freeze
+      return super unless tag == 'else'
       @else_block = BlockBody.new
     end
 
@@ -95,22 +97,22 @@ module Liquid
           set_attribute(key, value)
         end
       else
-        raise SyntaxError, 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, options[:locale].t("errors.syntax.for_invalid_in".freeze) unless p.id?('in'.freeze)
+      raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_in") unless p.id?('in')
       collection_name = p.expression
       @name = "#{@variable_name}-#{collection_name}"
       @collection_name = Expression.parse(collection_name)
-      @reversed = p.id?('reversed'.freeze)
+      @reversed = p.id?('reversed')
 
       while p.look(:id) && p.look(:colon, 1)
-        unless attribute = p.id?('limit'.freeze) || p.id?('offset'.freeze)
-          raise SyntaxError, 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)
@@ -162,7 +164,7 @@ module Liquid
         for_stack.push(loop_vars)
 
         begin
-          context['forloop'.freeze] = loop_vars
+          context['forloop'] = loop_vars
 
           segment.each do |item|
             context[@variable_name] = item
@@ -185,13 +187,13 @@ module Liquid
 
     def set_attribute(key, expr)
       case key
-      when 'offset'.freeze
-        @from = if expr == 'continue'.freeze
+      when 'offset'
+        @from = if expr == 'continue'
           :continue
         else
           Expression.parse(expr)
         end
-      when 'limit'.freeze
+      when 'limit'
         @limit = Expression.parse(expr)
       end
     end
@@ -211,5 +213,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('for'.freeze, For)
+  Template.register_tag('for', For)
 end

lib/liquid/tags/if.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   # If is the conditional block
   #
@@ -19,7 +21,7 @@ module Liquid
     def initialize(tag_name, markup, options)
       super
       @blocks = []
-      push_block('if'.freeze, markup)
+      push_block('if', markup)
     end
 
     def nodelist
@@ -32,7 +34,7 @@ module Liquid
     end
 
     def unknown_tag(tag, markup, tokens)
-      if ['elsif'.freeze, 'else'.freeze].include?(tag)
+      if ['elsif', 'else'].include?(tag)
         push_block(tag, markup)
       else
         super
@@ -40,11 +42,9 @@ module Liquid
     end
 
     def render_to_output_buffer(context, output)
-      context.stack do
-        @blocks.each do |block|
-          if block.evaluate(context)
-            return block.attachment.render_to_output_buffer(context, output)
-          end
+      @blocks.each do |block|
+        if block.evaluate(context)
+          return block.attachment.render_to_output_buffer(context, output)
         end
       end
 
@@ -54,7 +54,7 @@ module Liquid
     private
 
     def push_block(tag, markup)
-      block = if tag == 'else'.freeze
+      block = if tag == 'else'
         ElseCondition.new
       else
         parse_with_selected_parser(markup)
@@ -66,17 +66,17 @@ module Liquid
 
     def lax_parse(markup)
       expressions = markup.scan(ExpressionsAndOperators)
-      raise SyntaxError, 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(Regexp.last_match(1)), Regexp.last_match(2), Expression.parse(Regexp.last_match(3)))
 
       until expressions.empty?
         operator = expressions.pop.to_s.strip
 
-        raise SyntaxError, 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(Regexp.last_match(1)), Regexp.last_match(2), Expression.parse(Regexp.last_match(3)))
-        raise SyntaxError, options[:locale].t("errors.syntax.if".freeze) unless BOOLEAN_OPERATORS.include?(operator)
+        raise SyntaxError, options[:locale].t("errors.syntax.if") unless BOOLEAN_OPERATORS.include?(operator)
         new_condition.send(operator, condition)
         condition = new_condition
       end
@@ -94,7 +94,7 @@ module Liquid
     def parse_binary_comparisons(p)
       condition = parse_comparison(p)
       first_condition = condition
-      while op = (p.id?('and'.freeze) || p.id?('or'.freeze))
+      while (op = (p.id?('and') || p.id?('or')))
         child_condition = parse_comparison(p)
         condition.send(op, child_condition)
         condition = child_condition
@@ -104,7 +104,7 @@ module Liquid
 
     def parse_comparison(p)
       a = Expression.parse(p.expression)
-      if op = p.consume?(:comparison)
+      if (op = p.consume?(:comparison))
         b = Expression.parse(p.expression)
         Condition.new(a, op, b)
       else
@@ -119,5 +119,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('if'.freeze, If)
+  Template.register_tag('if', If)
 end

lib/liquid/tags/ifchanged.rb

@@ -1,19 +1,19 @@
+# frozen_string_literal: true
+
 module Liquid
   class Ifchanged < Block
     def render_to_output_buffer(context, output)
-      context.stack do
-        block_output = ''
-        super(context, block_output)
+      block_output = +''
+      super(context, block_output)
 
-        if block_output != context.registers[:ifchanged]
-          context.registers[:ifchanged] = block_output
-          output << block_output
-        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
   #
@@ -35,7 +37,7 @@ module Liquid
         end
 
       else
-        raise SyntaxError, options[:locale].t("errors.syntax.include".freeze)
+        raise SyntaxError, options[:locale].t("errors.syntax.include")
       end
     end
 
@@ -52,7 +54,7 @@ module Liquid
         parse_context: parse_context
       )
 
-      context_variable_name = template_name.split('/'.freeze).last
+      context_variable_name = template_name.split('/').last
 
       variable = if @variable_name_expr
         context.evaluate(@variable_name_expr)
@@ -101,5 +103,5 @@ module Liquid
     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
@@ -29,5 +31,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('increment'.freeze, Increment)
+  Template.register_tag('increment', Increment)
 end

lib/liquid/tags/raw.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Raw < Block
     Syntax = /\A\s*\z/
@@ -10,16 +12,16 @@ module Liquid
     end
 
     def parse(tokens)
-      @body = ''
-      while token = tokens.shift
+      @body = +''
+      while (token = tokens.shift)
         if token =~ FullTokenPossiblyInvalid
-          @body << Regexp.last_match(1) if Regexp.last_match(1) != "".freeze
+          @body << Regexp.last_match(1) if Regexp.last_match(1) != ""
           return if block_delimiter == Regexp.last_match(2)
         end
         @body << token unless token.empty?
       end
 
-      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_never_closed".freeze, block_name: block_name)
+      raise SyntaxError, parse_context.locale.t("errors.syntax.tag_never_closed", block_name: block_name)
     end
 
     def render_to_output_buffer(_context, output)
@@ -38,11 +40,11 @@ module Liquid
     protected
 
     def ensure_valid_markup(tag_name, markup, parse_context)
-      unless markup =~ Syntax
-        raise SyntaxError, 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

@@ -1,13 +1,17 @@
+# frozen_string_literal: true
+
 module Liquid
   class Render < Tag
     SYNTAX = /(#{QuotedString})#{QuotedFragment}*/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".freeze) unless markup =~ SYNTAX
+      raise SyntaxError, options[:locale].t("errors.syntax.render") unless markup =~ SYNTAX
 
       template_name = Regexp.last_match(1)
 
@@ -20,6 +24,10 @@ module Liquid
     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
@@ -50,5 +58,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('render'.freeze, Render)
+  Template.register_tag('render', Render)
 end

lib/liquid/tags/table_row.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class TableRow < Block
     Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)/o
@@ -14,26 +16,26 @@ module Liquid
           @attributes[key] = Expression.parse(value)
         end
       else
-        raise SyntaxError, options[:locale].t("errors.syntax.table_row".freeze)
+        raise SyntaxError, options[:locale].t("errors.syntax.table_row")
       end
     end
 
     def render_to_output_buffer(context, output)
-      (collection = context.evaluate(@collection_name)) || (return ''.freeze)
+      (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
 
-      cols = context.evaluate(@attributes['cols'.freeze]).to_i
+      cols = context.evaluate(@attributes['cols']).to_i
 
       output << "<tr class=\"row1\">\n"
       context.stack do
         tablerowloop = Liquid::TablerowloopDrop.new(length, cols)
-        context['tablerowloop'.freeze] = tablerowloop
+        context['tablerowloop'] = tablerowloop
 
         collection.each do |item|
           context[@variable_name] = item
@@ -61,5 +63,5 @@ module Liquid
     end
   end
 
-  Template.register_tag('tablerow'.freeze, TableRow)
+  Template.register_tag('tablerow', TableRow)
 end

lib/liquid/tags/unless.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require_relative 'if'
 
 module Liquid
@@ -7,18 +9,16 @@ module Liquid
   #
   class Unless < If
     def render_to_output_buffer(context, output)
-      context.stack do
-        # First condition is interpreted backwards ( if not )
-        first_block = @blocks.first
-        unless first_block.evaluate(context)
-          return first_block.attachment.render_to_output_buffer(context, output)
-        end
+      # First condition is interpreted backwards ( if not )
+      first_block = @blocks.first
+      unless first_block.evaluate(context)
+        return first_block.attachment.render_to_output_buffer(context, output)
+      end
 
-        # After the first condition unless works just like if
-        @blocks[1..-1].each do |block|
-          if block.evaluate(context)
-            return block.attachment.render_to_output_buffer(context, output)
-          end
+      # After the first condition unless works just like if
+      @blocks[1..-1].each do |block|
+        if block.evaluate(context)
+          return block.attachment.render_to_output_buffer(context, output)
         end
       end
 
@@ -26,5 +26,5 @@ module Liquid
     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
@@ -90,6 +92,14 @@ module Liquid
         @tags ||= TagRegistry.new
       end
 
+      def add_register(name, klass)
+        registers[name.to_s] = klass
+      end
+
+      def registers
+        @registers ||= {}
+      end
+
       def error_mode
         @error_mode ||= :lax
       end
@@ -165,7 +175,7 @@ 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
@@ -189,18 +199,26 @@ module Liquid
 
       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
         context.add_filters(args.pop)
       end
 
+      Template.registers.each do |key, register|
+        context_register[key] = register
+      end
+
       # Retrying a render resets resource usage
       context.resource_limits.reset
 
@@ -208,7 +226,7 @@ module Liquid
         # render the nodelist.
         # for performance reasons we get an array back here. join will make a string out of it.
         with_profiling(context) do
-          @root.render_to_output_buffer(context, output || '')
+          @root.render_to_output_buffer(context, output || +'')
         end
       rescue Liquid::MemoryError => e
         context.handle_error(e)

lib/liquid/tokenizer.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module Liquid
   class Tokenizer
     attr_reader :line_number, :for_liquid_tag

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)
@@ -50,7 +52,7 @@ module Liquid
       when Numeric
         obj
       when String
-        obj.strip =~ /\A-?\d+\.\d+\z/ ? BigDecimal(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)

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
@@ -102,13 +104,21 @@ module Liquid
       output
     end
 
+    def disabled?(_context)
+      false
+    end
+
+    def disabled_tags
+      []
+    end
+
     private
 
     def parse_filter_expressions(filter_name, unparsed_args)
       filter_args = []
       keyword_args = nil
       unparsed_args.each do |a|
-        if matches = a.match(JustTagAttributes)
+        if (matches = a.match(JustTagAttributes))
           keyword_args ||= {}
           keyword_args[matches[1]] = Expression.parse(matches[2])
         else

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].freeze
+    COMMAND_METHODS = ['size', 'first', 'last'].freeze
 
     attr_reader :name, :lookups
 

lib/liquid/version.rb

@@ -1,5 +1,6 @@
 # encoding: utf-8
+# frozen_string_literal: true
 
 module Liquid
-  VERSION = "4.0.3".freeze
+  VERSION = "4.0.3"
 end

liquid.gemspec

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

performance/benchmark.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'benchmark/ips'
 require_relative 'theme_runner'
 

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}+)/
 

performance/shopify/database.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'yaml'
 
 module Database
@@ -30,8 +32,8 @@ 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'] },
+        '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,
       }
 

performance/shopify/json_filter.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'json'
 
 module JsonFilter

performance/shopify/liquid.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 $LOAD_PATH.unshift(__dir__ + '/../../lib')
 require_relative '../../lib/liquid'
 

performance/shopify/money_filter.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module MoneyFilter
   def money_with_currency(money)
     return '' if money.nil?

performance/shopify/paginate.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class Paginate < Liquid::Block
   Syntax = /(#{Liquid::QuotedFragment})\s*(by\s*(\d+))?/
 

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}"

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>"

performance/shopify/weight_filter.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 module WeightFilter
   def weight(grams)
     format("%.2f", grams / 1000)

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.

test/integration/assign_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class AssignTest < Minitest::Test

test/integration/blank_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class FoobarTag < Liquid::Tag

test/integration/block_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class BlockTest < Minitest::Test

test/integration/capture_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class CaptureTest < Minitest::Test

test/integration/context_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ContextTest < Minitest::Test

test/integration/document_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class DocumentTest < Minitest::Test

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
 
@@ -48,7 +50,7 @@ class ProductDrop < Liquid::Drop
   end
 
   def user_input
-    "foo".taint
+    (+"foo").taint
   end
 
   protected
@@ -270,4 +272,11 @@ class DropsTest < Minitest::Test
     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 user_input 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
@@ -209,7 +211,10 @@ class ErrorHandlingTest < Minitest::Test
   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)
@@ -223,7 +228,10 @@ class ErrorHandlingTest < Minitest::Test
   def test_exception_renderer_exposing_non_liquid_error
     template = Liquid::Template.parse('This is a runtime error: {{ errors.runtime_error }}', line_numbers: true)
     exceptions = []
-    handler = ->(e) { exceptions << e; e.cause }
+    handler = ->(e) {
+      exceptions << e
+      e.cause
+    }
 
     output = template.render({ 'errors' => ErrorDrop.new }, exception_renderer: handler)
 

test/integration/filter_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 module MoneyFilter

test/integration/hash_ordering_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class HashOrderingTest < Minitest::Test

test/integration/output_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 module FunnyFilter

test/integration/parsing_quirks_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ParsingQuirksTest < Minitest::Test

test/integration/registers/disabled_tags_test.rb

@@ -0,0 +1,27 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class DisabledTagsTest < Minitest::Test
+  include Liquid
+
+  class DisableRaw < Block
+    disable_tags "raw"
+  end
+
+  class DisableRawEcho < Block
+    disable_tags "raw", "echo"
+  end
+
+  def test_disables_raw
+    with_custom_tag('disable', DisableRaw) do
+      assert_template_result 'raw usage is not allowed in this contextfoo', '{% disable %}{% raw %}Foobar{% endraw %}{% echo "foo" %}{% enddisable %}'
+    end
+  end
+
+  def test_disables_echo_and_raw
+    with_custom_tag('disable', DisableRawEcho) do
+      assert_template_result 'raw usage is not allowed in this contextecho usage is not allowed in this context', '{% disable %}{% raw %}Foobar{% endraw %}{% echo "foo" %}{% enddisable %}'
+    end
+  end
+end

test/integration/render_profiling_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class RenderProfilingTest < Minitest::Test

test/integration/security_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 module SecurityFilter

test/integration/standard_filter_test.rb

@@ -1,4 +1,5 @@
 # encoding: utf-8
+# frozen_string_literal: true
 
 require 'test_helper'
 

test/integration/tags/break_tag_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class BreakTagTest < Minitest::Test

test/integration/tags/continue_tag_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ContinueTagTest < Minitest::Test

test/integration/tags/echo_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class EchoTest < Minitest::Test

test/integration/tags/for_tag_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class ThingWithValue < Liquid::Drop

test/integration/tags/if_else_tag_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class IfElseTagTest < Minitest::Test

test/integration/tags/include_tag_test.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'test_helper'
 
 class TestFileSystem