Bump to 5.9.0

Co-authored-by: Gray Gilmore <[email protected]>

.github/dependabot.yaml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: github-actions
+    directory: "/"
+    schedule:
+      interval: weekly

.github/workflows/liquid.yml

@@ -14,24 +14,39 @@ jobs:
           - { ruby: 3.0, allowed-failure: false } # minimum supported
           - { ruby: 3.2, allowed-failure: false }
           - { ruby: 3.3, allowed-failure: false }
+          - { ruby: 3.3, allowed-failure: false }
           - { ruby: 3.4, allowed-failure: false } # latest
+          - {
+              ruby: 3.4,
+              allowed-failure: false,
+              rubyopt: "--enable-frozen-string-literal",
+            }
+          - { ruby: 3.4, allowed-failure: false, rubyopt: "--yjit" }
           - { ruby: ruby-head, allowed-failure: false }
+          - {
+              ruby: ruby-head,
+              allowed-failure: false,
+              rubyopt: "--enable-frozen-string-literal",
+            }
+          - { ruby: ruby-head, allowed-failure: false, rubyopt: "--yjit" }
     name: Test Ruby ${{ matrix.entry.ruby }}
     steps:
-      - uses: actions/checkout@v3
-      - uses: ruby/setup-ruby@v1
+      - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
+      - uses: ruby/setup-ruby@dffc446db9ba5a0c4446edb5bca1c5c473a806c5 # v1.235.0
         with:
           ruby-version: ${{ matrix.entry.ruby }}
           bundler-cache: true
           bundler: latest
       - run: bundle exec rake
         continue-on-error: ${{ matrix.entry.allowed-failure }}
+        env:
+          RUBYOPT: ${{ matrix.entry.rubyopt }}
 
   memory_profile:
     runs-on: ubuntu-latest
     steps:
-      - uses: actions/checkout@v3
-      - uses: ruby/setup-ruby@v1
+      - uses: actions/checkout@f43a0e5ff2bd294095638e18286ca9a3d1956744 # v3.6.0
+      - uses: ruby/setup-ruby@dffc446db9ba5a0c4446edb5bca1c5c473a806c5 # v1.235.0
         with:
           bundler-cache: true
       - run: bundle exec rake memory_profile:run

History.md

@@ -1,22 +1,38 @@
 # Liquid Change Log
 
-## 5.8.0 (unreleased)
+## 5.9.0
+* Introduce `:rigid` error mode for stricter, safer parsing of all tags [CP Clermont, Guilherme Carreiro]
 
-## 5.7.2 2025-01-30
+## 5.8.7
+* Expose body content in the `Doc` tag [James Meng]
 
-- Fix the `sort` filter to handle nested properties gracefully when their types don't match
+## 5.8.1
+
+* Fix `{% doc %}` tag to be visitable [Guilherme Carreiro]
+
+## 5.8.0
+
+* Introduce the new `{% doc %}` tag [Guilherme Carreiro]
+
+## 5.7.3
+
+* Raise Liquid::SyntaxError when parsing invalidly encoded strings [Chris AtLee]
+
+## 5.7.2 2025-01-31
+
+* Fix array filters to not support nested properties [Guilherme Carreiro]
 
 ## 5.7.1 2025-01-24
 
-* Fix the `find` and `find_index`filters to return `nil` when filtering empty arrays
-* Fix the `has` filter to return `false` when filtering empty arrays
+* Fix the `find` and `find_index`filters to return `nil` when filtering empty arrays [Guilherme Carreiro]
+* Fix the `has` filter to return `false` when filtering empty arrays [Guilherme Carreiro]
 
 ## 5.7.0 2025-01-16
 
 ### Features
 
-* Add `find`, `find_index`, `has`, and `reject` filters to arrays
-* Compatibility with Ruby 3.4
+* Add `find`, `find_index`, `has`, and `reject` filters to arrays [Guilherme Carreiro]
+* Compatibility with Ruby 3.4 [Ian Ker-Seymer]
 
 ## 5.6.4 2025-01-14
 

README.md

@@ -99,14 +99,14 @@ Setting the error mode of Liquid lets you specify how strictly you want your tem
 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.
 
-Liquid also comes with a stricter parser that can be used when editing templates to give better error messages
+Liquid also comes with different parsers that can be used when editing templates to give better error messages
 when templates are invalid. You can enable this new parser like this:
 
 ```ruby
-Liquid::Environment.default.error_mode = :strict
-Liquid::Environment.default.error_mode = :strict # Raises a SyntaxError when invalid syntax is used
-Liquid::Environment.default.error_mode = :warn # Adds strict errors to template.errors but continues as normal
-Liquid::Environment.default.error_mode = :lax # The default mode, accepts almost anything.
+Liquid::Environment.default.error_mode = :rigid  # Raises a SyntaxError when invalid syntax is used in all tags
+Liquid::Environment.default.error_mode = :strict # Raises a SyntaxError when invalid syntax is used in some tags
+Liquid::Environment.default.error_mode = :warn   # Adds strict errors to template.errors but continues as normal
+Liquid::Environment.default.error_mode = :lax    # The default mode, accepts almost anything.
 ```
 
 If you want to set the error mode only on specific templates you can pass `:error_mode` as an option to `parse`:

Rakefile

@@ -33,7 +33,7 @@ task :rubocop do
   end
 end
 
-desc('runs test suite with both strict and lax parsers')
+desc('runs test suite with lax, strict, and rigid parsers')
 task :test do
   ENV['LIQUID_PARSER_MODE'] = 'lax'
   Rake::Task['base_test'].invoke
@@ -42,6 +42,10 @@ task :test do
   Rake::Task['base_test'].reenable
   Rake::Task['base_test'].invoke
 
+  ENV['LIQUID_PARSER_MODE'] = 'rigid'
+  Rake::Task['base_test'].reenable
+  Rake::Task['base_test'].invoke
+
   if RUBY_ENGINE == 'ruby' || RUBY_ENGINE == 'truffleruby'
     ENV['LIQUID_PARSER_MODE'] = 'lax'
     Rake::Task['integration_test'].reenable
@@ -50,6 +54,10 @@ task :test do
     ENV['LIQUID_PARSER_MODE'] = 'strict'
     Rake::Task['integration_test'].reenable
     Rake::Task['integration_test'].invoke
+
+    ENV['LIQUID_PARSER_MODE'] = 'rigid'
+    Rake::Task['integration_test'].reenable
+    Rake::Task['integration_test'].invoke
   end
 end
 
@@ -80,8 +88,13 @@ namespace :benchmark do
     ruby "./performance/benchmark.rb strict"
   end
 
-  desc "Run the liquid benchmark with both lax and strict parsing"
-  task run: [:lax, :strict]
+  desc "Run the liquid benchmark with rigid parsing"
+  task :rigid do
+    ruby "./performance/benchmark.rb rigid"
+  end
+
+  desc "Run the liquid benchmark with lax, strict, and rigid parsing"
+  task run: [:lax, :strict, :rigid]
 
   desc "Run unit benchmarks"
   namespace :unit do

bin/render

@@ -0,0 +1,46 @@
+#!/usr/bin/env ruby
+# frozen_string_literal: true
+
+require 'bundler/setup'
+require 'liquid'
+
+class VirtualFileSystem
+  def initialize
+    snippet_1 = <<~LIQUID
+      <h1>
+        {{- greating | default: 'Hello' }}, {{ name | default: 'world' -}}!
+      </h1>
+    LIQUID
+    snippet_2 = <<~LIQUID
+      {%- for i in (1..5) -%}
+        > {{ i }}
+      {%- endfor -%}
+    LIQUID
+
+    @templates = {
+      'snippet-1' => snippet_1,
+      'snippet-2' => snippet_2,
+    }
+  end
+
+  def read_template_file(key)
+    @templates[key] || raise(Liquid::FileSystemError, "No such template '#{key}'")
+  end
+end
+
+def source
+  File.read(ARGV[0])
+rescue StandardError
+  'Usage: bin/render example/server/templates/index.liquid'
+end
+
+def assigns
+  {
+    'date' => Time.now,
+  }
+end
+
+puts Liquid::Template
+  .parse(source, error_mode: :rigid)
+  .tap { |t| t.registers[:file_system] = VirtualFileSystem.new }
+  .render(assigns)

lib/liquid/condition.rb

@@ -48,8 +48,8 @@ module Liquid
       @@operators
     end
 
-    def self.parse_expression(parse_context, markup)
-      @@method_literals[markup] || parse_context.parse_expression(markup)
+    def self.parse_expression(parse_context, markup, safe: false)
+      @@method_literals[markup] || parse_context.parse_expression(markup, safe: safe)
     end
 
     attr_reader :attachment, :child_condition

lib/liquid/environment.rb

@@ -34,7 +34,7 @@ module Liquid
       # @param file_system The default file system that is used
       #  to load templates from.
       # @param error_mode [Symbol] The default error mode for all templates
-      #  (either :strict, :warn, or :lax).
+      #  (either :rigid, :strict, :warn, or :lax).
       # @param exception_renderer [Proc] The exception renderer that is used to
       #   render exceptions.
       # @yieldparam environment [Environment] The environment instance that is being built.

lib/liquid/expression.rb

@@ -28,6 +28,10 @@ module Liquid
     FLOAT_REGEX = /\A(-?\d+)\.\d+\z/
 
     class << self
+      def safe_parse(parser, ss = StringScanner.new(""), cache = nil)
+        parse(parser.expression, ss, cache)
+      end
+
       def parse(markup, ss = StringScanner.new(""), cache = nil)
         return unless markup
 

lib/liquid/lexer.rb

@@ -161,6 +161,12 @@ module Liquid
         end
         # rubocop:enable Metrics/BlockNesting
         output << EOS
+      rescue ::ArgumentError => e
+        if e.message == "invalid byte sequence in #{ss.string.encoding}"
+          raise SyntaxError, "Invalid byte sequence in #{ss.string.encoding}"
+        else
+          raise
+        end
       end
 
       def raise_syntax_error(start_pos, ss)

lib/liquid/locales/en.yml

@@ -2,12 +2,14 @@
   errors:
     syntax:
       tag_unexpected_args: "Syntax Error in '%{tag}' - Valid syntax: %{tag}"
+      block_tag_unexpected_args: "Syntax Error in '%{tag}' - Valid syntax: {% %{tag} %}{% end%{tag} %}"
       assign: "Syntax Error in 'assign' - Valid syntax: assign [var] = [source]"
       capture: "Syntax Error in 'capture' - Valid syntax: capture [var]"
       case: "Syntax Error in 'case' - Valid syntax: case [condition]"
       case_invalid_when: "Syntax Error in tag 'case' - Valid when condition: {% when [condition] [or condition2...] %}"
       case_invalid_else: "Syntax Error in tag 'case' - Valid else condition: {% else %} (no parameters) "
       cycle: "Syntax Error in 'cycle' - Valid syntax: cycle [name :] var [, var2, var3 ...]"
+      doc_invalid_nested: "Syntax Error in 'doc' - Nested doc tags are not allowed"
       for: "Syntax Error in 'for loop' - Valid syntax: for [item] in [collection]"
       for_invalid_in: "For loops require an 'in' clause"
       for_invalid_attribute: "Invalid attribute in for loop. Valid attributes are limit and offset"
@@ -18,6 +20,7 @@
       invalid_template_encoding: "Invalid template encoding"
       render: "Syntax error in tag 'render' - Template name must be a quoted string"
       table_row: "Syntax Error in 'table_row loop' - Valid syntax: table_row [item] in [collection] cols=3"
+      table_row_invalid_attribute: "Invalid attribute '%{attribute}' in tablerow loop. Valid attributes are cols, limit, offset, and range"
       tag_never_closed: "'%{block_name}' tag was never closed"
       tag_termination: "Tag '%{token}' was not properly terminated with regexp: %{tag_end}"
       unexpected_else: "%{block_name} tag does not expect 'else' tag"

lib/liquid/parse_context.rb

@@ -50,7 +50,22 @@ module Liquid
       )
     end
 
-    def parse_expression(markup)
+    def safe_parse_expression(parser)
+      Expression.safe_parse(parser, @string_scanner, @expression_cache)
+    end
+
+    def parse_expression(markup, safe: false)
+      if !safe && @error_mode == :rigid
+        # parse_expression is a widely used API. To maintain backward
+        # compatibility while raising awareness about rigid parser standards,
+        # the safe flag supports API users make a deliberate decision.
+        #
+        # In rigid mode, markup MUST come from a string returned by the parser
+        # (e.g., parser.expression). We're not calling the parser here to
+        # prevent redundant parser overhead.
+        raise Liquid::InternalError, "unsafe parse_expression cannot be used in rigid mode"
+      end
+
       Expression.parse(markup, @string_scanner, @expression_cache)
     end
 

lib/liquid/parser_switching.rb

@@ -2,10 +2,22 @@
 
 module Liquid
   module ParserSwitching
+    # Do not use this.
+    #
+    # It's basically doing the same thing the {#parse_with_selected_parser},
+    # except this will try the strict parser regardless of the error mode,
+    # and fall back to the lax parser if the error mode is lax or warn,
+    # except when in rigid mode where it uses the rigid parser.
+    #
+    # @deprecated Use {#parse_with_selected_parser} instead.
     def strict_parse_with_error_mode_fallback(markup)
+      return rigid_parse_with_error_context(markup) if rigid_mode?
+
       strict_parse_with_error_context(markup)
     rescue SyntaxError => e
       case parse_context.error_mode
+      when :rigid
+        raise
       when :strict
         raise
       when :warn
@@ -16,11 +28,12 @@ module Liquid
 
     def parse_with_selected_parser(markup)
       case parse_context.error_mode
+      when :rigid  then rigid_parse_with_error_context(markup)
       when :strict then strict_parse_with_error_context(markup)
       when :lax    then lax_parse(markup)
       when :warn
         begin
-          strict_parse_with_error_context(markup)
+          rigid_parse_with_error_context(markup)
         rescue SyntaxError => e
           parse_context.warnings << e
           lax_parse(markup)
@@ -28,8 +41,20 @@ module Liquid
       end
     end
 
+    def rigid_mode?
+      parse_context.error_mode == :rigid
+    end
+
     private
 
+    def rigid_parse_with_error_context(markup)
+      rigid_parse(markup)
+    rescue SyntaxError => e
+      e.line_number    = line_number
+      e.markup_context = markup_context(markup)
+      raise e
+    end
+
     def strict_parse_with_error_context(markup)
       strict_parse(markup)
     rescue SyntaxError => e

lib/liquid/standardfilters.rb

@@ -3,7 +3,6 @@
 require 'cgi'
 require 'base64'
 require 'bigdecimal'
-
 module Liquid
   module StandardFilters
     MAX_I32 = (1 << 31) - 1
@@ -387,23 +386,7 @@ module Liquid
         end
       elsif ary.all? { |el| el.respond_to?(:[]) }
         begin
-          ary.sort do |a, b|
-            a = fetch_property(a, property)
-            b = fetch_property(b, property)
-
-            ##
-            # We handle nested properties gracefully to avoid breaking backward
-            # compatibility.
-            #
-            # However, we raise errors for incompatible types when no nested
-            # properties are used to maintain strict type checking in simple
-            # cases.
-            if has_nested_property?(property)
-              type_safe_compare(a, b) { |a, b| nil_safe_compare(a, b) }
-            else
-              nil_safe_compare(a, b)
-            end
-          end
+          ary.sort { |a, b| nil_safe_compare(a[property], b[property]) }
         rescue TypeError
           raise_property_error(property)
         end
@@ -432,7 +415,7 @@ module Liquid
         end
       elsif ary.all? { |el| el.respond_to?(:[]) }
         begin
-          ary.sort { |a, b| nil_safe_casecmp(fetch_property(a, property), fetch_property(b, property)) }
+          ary.sort { |a, b| nil_safe_casecmp(a[property], b[property]) }
         rescue TypeError
           raise_property_error(property)
         end
@@ -472,7 +455,7 @@ module Liquid
     #   Tests if any item in an array has a specific property value.
     # @liquid_description
     #   This requires you to provide both the property name and the associated value.
-    # @liquid_syntax array | some: string, string
+    # @liquid_syntax array | has: string, string
     # @liquid_return [boolean]
     def has(input, property, target_value = nil)
       filter_array(input, property, target_value, false) { |ary, &block| ary.any?(&block) }
@@ -520,7 +503,7 @@ module Liquid
         []
       else
         ary.uniq do |item|
-          fetch_property(item, property)
+          item[property]
         rescue TypeError
           raise_property_error(property)
         rescue NoMethodError
@@ -556,7 +539,7 @@ module Liquid
         if property == "to_liquid"
           e
         elsif e.respond_to?(:[])
-          r = fetch_property(e, property)
+          r = e[property]
           r.is_a?(Proc) ? r.call : r
         end
       end
@@ -580,7 +563,7 @@ module Liquid
         []
       else
         ary.reject do |item|
-          fetch_property(item, property).nil?
+          item[property].nil?
         rescue TypeError
           raise_property_error(property)
         rescue NoMethodError
@@ -728,7 +711,16 @@ module Liquid
       input.gsub(/\r?\n/, "<br />\n")
     end
 
-    # Reformat a date using Ruby's core Time#strftime( string ) -> string
+    # @liquid_public_docs
+    # @liquid_type filter
+    # @liquid_category date
+    # @liquid_summary
+    #   Formats a date according to a specified format string.
+    # @liquid_description
+    #   This filter formats a date using various format specifiers. If the format string is empty,
+    #   the original input is returned. If the input cannot be converted to a date, the original input is returned.
+    #
+    #   The following format specifiers can be used:
     #
     #   %a - The abbreviated weekday name (``Sun'')
     #   %A - The  full  weekday  name (``Sunday'')
@@ -757,8 +749,8 @@ module Liquid
     #   %Y - Year with century
     #   %Z - Time zone name
     #   %% - Literal ``%'' character
-    #
-    #   See also: http://www.ruby-doc.org/core/Time.html#method-i-strftime
+    # @liquid_syntax date | date: string
+    # @liquid_return [string]
     def date(input, format)
       str_format = Utils.to_s(format)
       return input if str_format.empty?
@@ -966,7 +958,7 @@ module Liquid
         if property.nil?
           item
         elsif item.respond_to?(:[])
-          fetch_property(item, property)
+          item[property]
         else
           0
         end
@@ -992,9 +984,9 @@ module Liquid
 
       block.call(ary) do |item|
         if target_value.nil?
-          fetch_property(item, property)
+          item[property]
         else
-          fetch_property(item, property) == target_value
+          item[property] == target_value
         end
       rescue TypeError
         raise_property_error(property)
@@ -1004,37 +996,8 @@ module Liquid
       end
     end
 
-    def fetch_property(drop, property_or_keys)
-      ##
-      # This keeps backward compatibility by supporting properties containing
-      # dots. This is valid in Liquid syntax and used in some runtimes, such as
-      # Shopify with metafields.
-      #
-      # Using this approach, properties like 'price.value' can be accessed in
-      # both of the following examples:
-      #
-      # ```
-      # [
-      #   { 'name' => 'Item 1', 'price.price' => 40000 },
-      #   { 'name' => 'Item 2', 'price' => { 'value' => 39900 } }
-      # ]
-      # ```
-      value = drop[property_or_keys]
-
-      return value if !value.nil? || !has_nested_property?(property_or_keys)
-
-      keys = property_or_keys.split('.')
-      keys.reduce(drop) do |drop, key|
-        drop.respond_to?(:[]) ? drop[key] : drop
-      end
-    end
-
-    def has_nested_property?(property)
-      property.is_a?(String) && property.include?('.')
-    end
-
     def raise_property_error(property)
-      raise Liquid::ArgumentError, "cannot select the property '#{property}'"
+      raise Liquid::ArgumentError, "cannot select the property '#{Utils.to_s(property)}'"
     end
 
     def apply_operation(input, operand, operation)
@@ -1056,16 +1019,6 @@ module Liquid
       end
     end
 
-    def type_safe_compare(a, b)
-      klass_a = a.class
-      klass_b = b.class
-
-      # Converting classes to string to have a deterministic comparison.
-      return nil_safe_casecmp(klass_a, klass_b) if klass_a != klass_b
-
-      yield(a, b)
-    end
-
     def nil_safe_casecmp(a, b)
       if !a.nil? && !b.nil?
         a.to_s.casecmp(b.to_s)
@@ -1116,7 +1069,10 @@ module Liquid
       end
 
       def uniq(&block)
-        to_a.uniq(&block)
+        to_a.uniq do |item|
+          item = Utils.to_liquid_value(item)
+          block ? yield(item) : item
+        end
       end
 
       def compact

lib/liquid/tag.rb

@@ -68,8 +68,12 @@ module Liquid
 
     private
 
-    def parse_expression(markup)
-      parse_context.parse_expression(markup)
+    def safe_parse_expression(parser)
+      parse_context.safe_parse_expression(parser)
+    end
+
+    def parse_expression(markup, safe: false)
+      parse_context.parse_expression(markup, safe: safe)
     end
   end
 end

lib/liquid/tags.rb

@@ -19,6 +19,7 @@ require_relative "tags/comment"
 require_relative "tags/raw"
 require_relative "tags/render"
 require_relative "tags/cycle"
+require_relative "tags/doc"
 
 module Liquid
   module Tags
@@ -42,6 +43,7 @@ module Liquid
       'if' => If,
       'echo' => Echo,
       'tablerow' => TableRow,
+      'doc' => Doc,
     }.freeze
   end
 end

lib/liquid/tags/assign.rb

@@ -9,6 +9,10 @@ module Liquid
   #   Creates a new variable.
   # @liquid_description
   #   You can create variables of any [basic type](/docs/api/liquid/basics#types), [object](/docs/api/liquid/objects), or object property.
+  #
+  #   > Caution:
+  #   > Predefined Liquid objects can be overridden by variables with the same name.
+  #   > To make sure that you can access all Liquid objects, make sure that your variable name doesn't match a predefined object's name.
   # @liquid_syntax
   #   {% assign variable_name = value %}
   # @liquid_syntax_keyword variable_name The name of the variable being created.

lib/liquid/tags/capture.rb

@@ -9,6 +9,10 @@ module Liquid
   #   Creates a new variable with a string value.
   # @liquid_description
   #   You can create complex strings with Liquid logic and variables.
+  #
+  #   > Caution:
+  #   > Predefined Liquid objects can be overridden by variables with the same name.
+  #   > To make sure that you can access all Liquid objects, make sure that your variable name doesn't match a predefined object's name.
   # @liquid_syntax
   #   {% capture variable %}
   #     value

lib/liquid/tags/case.rb

@@ -31,12 +31,7 @@ module Liquid
     def initialize(tag_name, markup, options)
       super
       @blocks = []
-
-      if markup =~ Syntax
-        @left = parse_expression(Regexp.last_match(1))
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.case")
-      end
+      parse_with_selected_parser(markup)
     end
 
     def parse(tokens)
@@ -91,9 +86,50 @@ module Liquid
 
     private
 
+    def rigid_parse(markup)
+      parser = @parse_context.new_parser(markup)
+      @left = safe_parse_expression(parser)
+      parser.consume(:end_of_string)
+    end
+
+    def strict_parse(markup)
+      lax_parse(markup)
+    end
+
+    def lax_parse(markup)
+      if markup =~ Syntax
+        @left = parse_expression(Regexp.last_match(1))
+      else
+        raise SyntaxError, options[:locale].t("errors.syntax.case")
+      end
+    end
+
     def record_when_condition(markup)
       body = new_body
 
+      if rigid_mode?
+        parse_rigid_when(markup, body)
+      else
+        parse_lax_when(markup, body)
+      end
+    end
+
+    def parse_rigid_when(markup, body)
+      parser = @parse_context.new_parser(markup)
+
+      loop do
+        expr = safe_parse_expression(parser)
+        block = Condition.new(@left, '==', expr)
+        block.attach(body)
+        @blocks << block
+
+        break unless parser.id?('or') || parser.consume?(:comma)
+      end
+
+      parser.consume(:end_of_string)
+    end
+
+    def parse_lax_when(markup, body)
       while markup
         unless markup =~ WhenSyntax
           raise SyntaxError, options[:locale].t("errors.syntax.case_invalid_when")

lib/liquid/tags/cycle.rb

@@ -17,23 +17,13 @@ module Liquid
   class Cycle < Tag
     SimpleSyntax = /\A#{QuotedFragment}+/o
     NamedSyntax  = /\A(#{QuotedFragment})\s*\:\s*(.*)/om
+    UNNAMED_CYCLE_PATTERN = /\w+:0x\h{8}/
 
     attr_reader :variables
 
     def initialize(tag_name, markup, options)
       super
-      case markup
-      when NamedSyntax
-        @variables = variables_from_string(Regexp.last_match(2))
-        @name      = parse_expression(Regexp.last_match(1))
-        @is_named = true
-      when SimpleSyntax
-        @variables = variables_from_string(markup)
-        @name      = @variables.to_s
-        @is_named = !@name.match?(/\w+:0x\h{8}/)
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.cycle")
-      end
+      parse_with_selected_parser(markup)
     end
 
     def named?
@@ -65,19 +55,82 @@ module Liquid
 
     private
 
+    # cycle [name:] expression(, expression)*
+    def rigid_parse(markup)
+      p = @parse_context.new_parser(markup)
+
+      @variables = []
+
+      raise SyntaxError, options[:locale].t("errors.syntax.cycle") if p.look(:end_of_string)
+
+      first_expression = safe_parse_expression(p)
+      if p.look(:colon)
+        # cycle name: expr1, expr2, ...
+        @name = first_expression
+        @is_named = true
+        p.consume(:colon)
+        # After the colon, parse the first variable (required for named cycles)
+        @variables << maybe_dup_lookup(safe_parse_expression(p))
+      else
+        # cycle expr1, expr2, ...
+        @variables << maybe_dup_lookup(first_expression)
+      end
+
+      # Parse remaining comma-separated expressions
+      while p.consume?(:comma)
+        break if p.look(:end_of_string)
+
+        @variables << maybe_dup_lookup(safe_parse_expression(p))
+      end
+
+      p.consume(:end_of_string)
+
+      unless @is_named
+        @name = @variables.to_s
+        @is_named = !@name.match?(UNNAMED_CYCLE_PATTERN)
+      end
+    end
+
+    def strict_parse(markup)
+      lax_parse(markup)
+    end
+
+    def lax_parse(markup)
+      case markup
+      when NamedSyntax
+        @variables = variables_from_string(Regexp.last_match(2))
+        @name      = parse_expression(Regexp.last_match(1))
+        @is_named = true
+      when SimpleSyntax
+        @variables = variables_from_string(markup)
+        @name      = @variables.to_s
+        @is_named = !@name.match?(UNNAMED_CYCLE_PATTERN)
+      else
+        raise SyntaxError, options[:locale].t("errors.syntax.cycle")
+      end
+    end
+
     def variables_from_string(markup)
       markup.split(',').collect do |var|
         var =~ /\s*(#{QuotedFragment})\s*/o
         next unless Regexp.last_match(1)
 
-        # Expression Parser returns cached objects, and we need to dup them to
-        # start the cycle over for each new cycle call.
-        # Liquid-C does not have a cache, so we don't need to dup the object.
         var = parse_expression(Regexp.last_match(1))
-        var.is_a?(VariableLookup) ? var.dup : var
+        maybe_dup_lookup(var)
       end.compact
     end
 
+    # For backwards compatibility, whenever a lookup is used in an unnamed cycle,
+    # we make it so that the @variables.to_s produces different strings for cycles
+    # called with the same arguments (since @variables.to_s is used as the cycle counter key)
+    # This makes it so {% cycle a, b %} and {% cycle a, b %} have independent counters even if a and b share value.
+    # This is not true for literal values, {% cycle "a", "b" %} and {% cycle "a", "b" %} share the same counter.
+    # I was really scratching my head about this one, but migrating away from this would be more headache
+    # than it's worth. So we're keeping this quirk for now.
+    def maybe_dup_lookup(var)
+      var.is_a?(VariableLookup) ? var.dup : var
+    end
+
     class ParseTreeVisitor < Liquid::ParseTreeVisitor
       def children
         Array(@node.variables)

lib/liquid/tags/decrement.rb

@@ -7,10 +7,14 @@ module Liquid
   # @liquid_name decrement
   # @liquid_summary
   #   Creates a new variable, with a default value of -1, that's decreased by 1 with each subsequent call.
+  #
+  #   > Caution:
+  #   > Predefined Liquid objects can be overridden by variables with the same name.
+  #   > To make sure that you can access all Liquid objects, make sure that your variable name doesn't match a predefined object's name.
   # @liquid_description
   #   Variables that are declared with `decrement` are unique to the [layout](/themes/architecture/layouts), [template](/themes/architecture/templates),
   #   or [section](/themes/architecture/sections) file that they're created in. However, the variable is shared across
-  #   [snippets](/themes/architecture#snippets) included in the file.
+  #   [snippets](/themes/architecture/snippets) included in the file.
   #
   #   Similarly, variables that are created with `decrement` are independent from those created with [`assign`](/docs/api/liquid/tags/assign)
   #   and [`capture`](/docs/api/liquid/tags/capture). However, `decrement` and [`increment`](/docs/api/liquid/tags/increment) share

lib/liquid/tags/doc.rb

@@ -0,0 +1,81 @@
+# frozen_string_literal: true
+
+module Liquid
+  # @liquid_public_docs
+  # @liquid_type tag
+  # @liquid_category syntax
+  # @liquid_name doc
+  # @liquid_summary
+  #   Documents template elements with annotations.
+  # @liquid_description
+  #   The `doc` tag allows developers to include documentation within Liquid
+  #   templates. Any content inside `doc` tags is not rendered or outputted.
+  #   Liquid code inside will be parsed but not executed. This facilitates
+  #   tooling support for features like code completion, linting, and inline
+  #   documentation.
+  #
+  #   For detailed documentation syntax and examples, see the
+  #   [`LiquidDoc` reference](/docs/storefronts/themes/tools/liquid-doc).
+  #
+  # @liquid_syntax
+  #   {% doc %}
+  #     Renders a message.
+  #
+  #     @param {string} foo - A string value.
+  #     @param {string} [bar] - An optional string value.
+  #
+  #     @example
+  #     {% render 'message', foo: 'Hello', bar: 'World' %}
+  #   {% enddoc %}
+  class Doc < Block
+    NO_UNEXPECTED_ARGS = /\A\s*\z/
+
+    def initialize(tag_name, markup, parse_context)
+      super
+      ensure_valid_markup(tag_name, markup, parse_context)
+    end
+
+    def parse(tokens)
+      @body = +""
+
+      while (token = tokens.shift)
+        tag_name = token =~ BlockBody::FullTokenPossiblyInvalid && Regexp.last_match(2)
+
+        raise_nested_doc_error if tag_name == @tag_name
+
+        if tag_name == block_delimiter
+          parse_context.trim_whitespace = (token[-3] == WhitespaceControl)
+          @body << Regexp.last_match(1) if Regexp.last_match(1) != ""
+          return
+        end
+        @body << token unless token.empty?
+      end
+
+      raise_tag_never_closed(block_name)
+    end
+
+    def render_to_output_buffer(_context, output)
+      output
+    end
+
+    def blank?
+      @body.empty?
+    end
+
+    def nodelist
+      [@body]
+    end
+
+    private
+
+    def ensure_valid_markup(tag_name, markup, parse_context)
+      unless NO_UNEXPECTED_ARGS.match?(markup)
+        raise SyntaxError, parse_context.locale.t("errors.syntax.block_tag_unexpected_args", tag: tag_name)
+      end
+    end
+
+    def raise_nested_doc_error
+      raise SyntaxError, parse_context.locale.t("errors.syntax.doc_invalid_nested")
+    end
+  end
+end

lib/liquid/tags/for.rb

@@ -20,8 +20,8 @@ module Liquid
   # @liquid_syntax_keyword variable The current item in the array.
   # @liquid_syntax_keyword array The array to iterate over.
   # @liquid_syntax_keyword expression The expression to render for each iteration.
-  # @liquid_optional_param limit [number] The number of iterations to perform.
-  # @liquid_optional_param offset [number] The 1-based index to start iterating at.
+  # @liquid_optional_param limit: [number] The number of iterations to perform.
+  # @liquid_optional_param offset: [number] The 1-based index to start iterating at.
   # @liquid_optional_param range [untyped] A custom numeric range to iterate over.
   # @liquid_optional_param reversed [untyped] Iterate in reverse order.
   class For < Block
@@ -93,7 +93,7 @@ module Liquid
       raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_in") unless p.id?('in')
 
       collection_name  = p.expression
-      @collection_name = parse_expression(collection_name)
+      @collection_name = parse_expression(collection_name, safe: true)
 
       @name     = "#{@variable_name}-#{collection_name}"
       @reversed = p.id?('reversed')
@@ -104,13 +104,17 @@ module Liquid
           raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_attribute")
         end
         p.consume(:colon)
-        set_attribute(attribute, p.expression)
+        set_attribute(attribute, p.expression, safe: true)
       end
       p.consume(:end_of_string)
     end
 
     private
 
+    def rigid_parse(markup)
+      strict_parse(markup)
+    end
+
     def collection_segment(context)
       offsets = context.registers[:for] ||= {}
 
@@ -174,16 +178,16 @@ module Liquid
       output
     end
 
-    def set_attribute(key, expr)
+    def set_attribute(key, expr, safe: false)
       case key
       when 'offset'
         @from = if expr == 'continue'
           :continue
         else
-          parse_expression(expr)
+          parse_expression(expr, safe: safe)
         end
       when 'limit'
-        @limit = parse_expression(expr)
+        @limit = parse_expression(expr, safe: safe)
       end
     end
 

lib/liquid/tags/if.rb

@@ -66,6 +66,10 @@ module Liquid
 
     private
 
+    def rigid_parse(markup)
+      strict_parse(markup)
+    end
+
     def push_block(tag, markup)
       block = if tag == 'else'
         ElseCondition.new
@@ -77,8 +81,8 @@ module Liquid
       block.attach(new_body)
     end
 
-    def parse_expression(markup)
-      Condition.parse_expression(parse_context, markup)
+    def parse_expression(markup, safe: false)
+      Condition.parse_expression(parse_context, markup, safe: safe)
     end
 
     def lax_parse(markup)
@@ -120,9 +124,9 @@ module Liquid
     end
 
     def parse_comparison(p)
-      a = parse_expression(p.expression)
+      a = parse_expression(p.expression, safe: true)
       if (op = p.consume?(:comparison))
-        b = parse_expression(p.expression)
+        b = parse_expression(p.expression, safe: true)
         Condition.new(a, op, b)
       else
         Condition.new(a)

lib/liquid/tags/include.rb

@@ -6,7 +6,7 @@ module Liquid
   # @liquid_category theme
   # @liquid_name include
   # @liquid_summary
-  #   Renders a [snippet](/themes/architecture#snippets).
+  #   Renders a [snippet](/themes/architecture/snippets).
   # @liquid_description
   #   Inside the snippet, you can access and alter variables that are [created](/docs/api/liquid/tags/variable-tags) outside of the
   #   snippet.
@@ -27,24 +27,7 @@ module Liquid
 
     def initialize(tag_name, markup, options)
       super
-
-      if markup =~ SYNTAX
-
-        template_name = Regexp.last_match(1)
-        variable_name = Regexp.last_match(3)
-
-        @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] = parse_expression(value)
-        end
-
-      else
-        raise SyntaxError, options[:locale].t("errors.syntax.include")
-      end
+      parse_with_selected_parser(markup)
     end
 
     def parse(_tokens)
@@ -101,6 +84,49 @@ module Liquid
     alias_method :parse_context, :options
     private :parse_context
 
+    def rigid_parse(markup)
+      p = @parse_context.new_parser(markup)
+
+      @template_name_expr = safe_parse_expression(p)
+      @variable_name_expr = safe_parse_expression(p) if p.id?("for") || p.id?("with")
+      @alias_name         = p.consume(:id) if p.id?("as")
+
+      p.consume?(:comma)
+
+      @attributes = {}
+      while p.look(:id)
+        key = p.consume
+        p.consume(:colon)
+        @attributes[key] = safe_parse_expression(p)
+        p.consume?(:comma)
+      end
+
+      p.consume(:end_of_string)
+    end
+
+    def strict_parse(markup)
+      lax_parse(markup)
+    end
+
+    def lax_parse(markup)
+      if markup =~ SYNTAX
+        template_name = Regexp.last_match(1)
+        variable_name = Regexp.last_match(3)
+
+        @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] = parse_expression(value)
+        end
+
+      else
+        raise SyntaxError, options[:locale].t("errors.syntax.include")
+      end
+    end
+
     class ParseTreeVisitor < Liquid::ParseTreeVisitor
       def children
         [

lib/liquid/tags/increment.rb

@@ -7,10 +7,14 @@ module Liquid
   # @liquid_name increment
   # @liquid_summary
   #   Creates a new variable, with a default value of 0, that's increased by 1 with each subsequent call.
+  #
+  #   > Caution:
+  #   > Predefined Liquid objects can be overridden by variables with the same name.
+  #   > To make sure that you can access all Liquid objects, make sure that your variable name doesn't match a predefined object's name.
   # @liquid_description
   #   Variables that are declared with `increment` are unique to the [layout](/themes/architecture/layouts), [template](/themes/architecture/templates),
   #   or [section](/themes/architecture/sections) file that they're created in. However, the variable is shared across
-  #   [snippets](/themes/architecture#snippets) included in the file.
+  #   [snippets](/themes/architecture/snippets) included in the file.
   #
   #   Similarly, variables that are created with `increment` are independent from those created with [`assign`](/docs/api/liquid/tags/assign)
   #   and [`capture`](/docs/api/liquid/tags/capture). However, `increment` and [`decrement`](/docs/api/liquid/tags/decrement) share

lib/liquid/tags/render.rb

@@ -6,7 +6,7 @@ module Liquid
   # @liquid_category theme
   # @liquid_name render
   # @liquid_summary
-  #   Renders a [snippet](/themes/architecture#snippets) or [app block](/themes/architecture/sections/section-schema#render-app-blocks).
+  #   Renders a [snippet](/themes/architecture/snippets) or [app block](/themes/architecture/sections/section-schema#render-app-blocks).
   # @liquid_description
   #   Inside snippets and app blocks, you can't directly access variables that are [created](/docs/api/liquid/tags/variable-tags) outside
   #   of the snippet or app block. However, you can [specify variables as parameters](/docs/api/liquid/tags/render#render-passing-variables-to-a-snippet)
@@ -35,22 +35,7 @@ module Liquid
 
     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)
-      @is_for_loop = (with_or_for == FOR)
-
-      @attributes = {}
-      markup.scan(TagAttributes) do |key, value|
-        @attributes[key] = parse_expression(value)
-      end
+      parse_with_selected_parser(markup)
     end
 
     def for_loop?
@@ -99,6 +84,55 @@ module Liquid
       output
     end
 
+    # render (string) (with|for expression)? (as id)? (key: value)*
+    def rigid_parse(markup)
+      p = @parse_context.new_parser(markup)
+
+      @template_name_expr = parse_expression(rigid_template_name(p), safe: true)
+      with_or_for         = p.id?("for") || p.id?("with")
+      @variable_name_expr = safe_parse_expression(p) if with_or_for
+      @alias_name         = p.consume(:id) if p.id?("as")
+      @is_for_loop        = (with_or_for == FOR)
+
+      p.consume?(:comma)
+
+      @attributes = {}
+      while p.look(:id)
+        key = p.consume
+        p.consume(:colon)
+        @attributes[key] = safe_parse_expression(p)
+        p.consume?(:comma)
+      end
+
+      p.consume(:end_of_string)
+    end
+
+    def rigid_template_name(p)
+      p.consume(:string)
+    end
+
+    def strict_parse(markup)
+      lax_parse(markup)
+    end
+
+    def lax_parse(markup)
+      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)
+      @is_for_loop = (with_or_for == FOR)
+
+      @attributes = {}
+      markup.scan(TagAttributes) do |key, value|
+        @attributes[key] = parse_expression(value)
+      end
+    end
+
     class ParseTreeVisitor < Liquid::ParseTreeVisitor
       def children
         [

lib/liquid/tags/table_row.rb

@@ -19,17 +19,54 @@ module Liquid
   # @liquid_syntax_keyword variable The current item in the array.
   # @liquid_syntax_keyword array The array to iterate over.
   # @liquid_syntax_keyword expression The expression to render.
-  # @liquid_optional_param cols [number] The number of columns that the table should have.
-  # @liquid_optional_param limit [number] The number of iterations to perform.
-  # @liquid_optional_param offset [number] The 1-based index to start iterating at.
+  # @liquid_optional_param cols: [number] The number of columns that the table should have.
+  # @liquid_optional_param limit: [number] The number of iterations to perform.
+  # @liquid_optional_param offset: [number] The 1-based index to start iterating at.
   # @liquid_optional_param range [untyped] A custom numeric range to iterate over.
   class TableRow < Block
     Syntax = /(\w+)\s+in\s+(#{QuotedFragment}+)/o
+    ALLOWED_ATTRIBUTES = ['cols', 'limit', 'offset', 'range'].freeze
 
     attr_reader :variable_name, :collection_name, :attributes
 
     def initialize(tag_name, markup, options)
       super
+      parse_with_selected_parser(markup)
+    end
+
+    def rigid_parse(markup)
+      p = @parse_context.new_parser(markup)
+
+      @variable_name = p.consume(:id)
+
+      unless p.id?("in")
+        raise SyntaxError, options[:locale].t("errors.syntax.for_invalid_in")
+      end
+
+      @collection_name = safe_parse_expression(p)
+
+      p.consume?(:comma)
+
+      @attributes = {}
+      while p.look(:id)
+        key = p.consume
+        unless ALLOWED_ATTRIBUTES.include?(key)
+          raise SyntaxError, options[:locale].t("errors.syntax.table_row_invalid_attribute", attribute: key)
+        end
+
+        p.consume(:colon)
+        @attributes[key] = safe_parse_expression(p)
+        p.consume?(:comma)
+      end
+
+      p.consume(:end_of_string)
+    end
+
+    def strict_parse(markup)
+      lax_parse(markup)
+    end
+
+    def lax_parse(markup)
       if markup =~ Syntax
         @variable_name   = Regexp.last_match(1)
         @collection_name = parse_expression(Regexp.last_match(2))

lib/liquid/template.rb

@@ -2,7 +2,7 @@
 
 module Liquid
   # Templates are central to liquid.
-  # Interpretating templates is a two step process. First you compile the
+  # Interpreting templates is a two step process. First you compile the
   # source code you got. During compile time some extensive error checking is performed.
   # your code should expect to get some SyntaxErrors.
   #
@@ -24,7 +24,8 @@ module Liquid
       # Sets how strict the parser should be.
       # :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.
+      # :strict enforces correct syntax for most tags
+      # :rigid enforces correct syntax for all tags
       def error_mode=(mode)
         Deprecations.warn("Template.error_mode=", "Environment#error_mode=")
         Environment.default.error_mode = mode

lib/liquid/tokenizer.rb

@@ -103,6 +103,12 @@ module Liquid
 
       pos = @ss.pos -= 2
       @source.byteslice(start, pos - start)
+    rescue ::ArgumentError => e
+      if e.message == "invalid byte sequence in #{@ss.string.encoding}"
+        raise SyntaxError, "Invalid byte sequence in #{@ss.string.encoding}"
+      else
+        raise
+      end
     end
 
     def next_variable_token

lib/liquid/utils.rb

@@ -2,6 +2,9 @@
 
 module Liquid
   module Utils
+    DECIMAL_REGEX = /\A-?\d+\.\d+\z/
+    UNIX_TIMESTAMP_REGEX = /\A\d+\z/
+
     def self.slice_collection(collection, from, to)
       if (from != 0 || !to.nil?) && collection.respond_to?(:load_slice)
         collection.load_slice(from, to)
@@ -52,7 +55,7 @@ module Liquid
       when Numeric
         obj
       when String
-        /\A-?\d+\.\d+\z/.match?(obj.strip) ? BigDecimal(obj) : obj.to_i
+        DECIMAL_REGEX.match?(obj.strip) ? BigDecimal(obj) : obj.to_i
       else
         if obj.respond_to?(:to_number)
           obj.to_number
@@ -73,7 +76,7 @@ module Liquid
       case obj
       when 'now', 'today'
         Time.now
-      when /\A\d+\z/, Integer
+      when UNIX_TIMESTAMP_REGEX, Integer
         Time.at(obj.to_i)
       when String
         Time.parse(obj)

lib/liquid/variable.rb

@@ -54,7 +54,7 @@ module Liquid
           next unless f =~ /\w+/
           filtername = Regexp.last_match(0)
           filterargs = f.scan(FilterArgsRegex).flatten
-          @filters << parse_filter_expressions(filtername, filterargs)
+          @filters << lax_parse_filter_expressions(filtername, filterargs)
         end
       end
     end
@@ -65,15 +65,26 @@ module Liquid
 
       return if p.look(:end_of_string)
 
-      @name = parse_context.parse_expression(p.expression)
+      @name = parse_context.safe_parse_expression(p)
       while p.consume?(:pipe)
         filtername = p.consume(:id)
         filterargs = p.consume?(:colon) ? parse_filterargs(p) : Const::EMPTY_ARRAY
-        @filters << parse_filter_expressions(filtername, filterargs)
+        @filters << lax_parse_filter_expressions(filtername, filterargs)
       end
       p.consume(:end_of_string)
     end
 
+    def rigid_parse(markup)
+      @filters = []
+      p = @parse_context.new_parser(markup)
+
+      return if p.look(:end_of_string)
+
+      @name = parse_context.safe_parse_expression(p)
+      @filters << rigid_parse_filter_expressions(p) while p.consume?(:pipe)
+      p.consume(:end_of_string)
+    end
+
     def parse_filterargs(p)
       # first argument
       filterargs = [p.argument]
@@ -122,7 +133,7 @@ module Liquid
 
     private
 
-    def parse_filter_expressions(filter_name, unparsed_args)
+    def lax_parse_filter_expressions(filter_name, unparsed_args)
       filter_args  = []
       keyword_args = nil
       unparsed_args.each do |a|
@@ -138,6 +149,46 @@ module Liquid
       result
     end
 
+    # Surprisingly, positional and keyword arguments can be mixed.
+    #
+    # filter = filtername [":" filterargs?]
+    # filterargs = argument ("," argument)*
+    # argument = (positional_argument | keyword_argument)
+    # positional_argument = expression
+    # keyword_argument = id ":" expression
+    def rigid_parse_filter_expressions(p)
+      filtername = p.consume(:id)
+      filter_args = []
+      keyword_args = {}
+
+      if p.consume?(:colon)
+        # Parse first argument (no leading comma)
+        argument(p, filter_args, keyword_args) unless end_of_arguments?(p)
+
+        # Parse remaining arguments (with leading commas) and optional trailing comma
+        argument(p, filter_args, keyword_args) while p.consume?(:comma) && !end_of_arguments?(p)
+      end
+
+      result = [filtername, filter_args]
+      result << keyword_args unless keyword_args.empty?
+      result
+    end
+
+    def argument(p, positional_arguments, keyword_arguments)
+      if p.look(:id) && p.look(:colon, 1)
+        key = p.consume(:id)
+        p.consume(:colon)
+        value = parse_context.safe_parse_expression(p)
+        keyword_arguments[key] = value
+      else
+        positional_arguments << parse_context.safe_parse_expression(p)
+      end
+    end
+
+    def end_of_arguments?(p)
+      p.look(:pipe) || p.look(:end_of_string)
+    end
+
     def evaluate_filter_expressions(context, filter_args, filter_kwargs)
       parsed_args = filter_args.map { |expr| context.evaluate(expr) }
       if filter_kwargs

lib/liquid/version.rb

@@ -2,5 +2,5 @@
 # frozen_string_literal: true
 
 module Liquid
-  VERSION = "5.7.2"
+  VERSION = "5.9.0"
 end

test/integration/context_test.rb

@@ -632,7 +632,7 @@ class ContextTest < Minitest::Test
   end
 
   def test_has_key_will_not_add_an_error_for_missing_keys
-    with_error_mode(:strict) do
+    with_error_modes(:strict) do
       context = Context.new
       context.key?('unknown')
       assert_empty(context.errors)

test/integration/error_handling_test.rb

@@ -67,7 +67,7 @@ class ErrorHandlingTest < Minitest::Test
   end
 
   def test_unrecognized_operator
-    with_error_mode(:strict) do
+    with_error_modes(:strict) do
       assert_raises(SyntaxError) do
         Liquid::Template.parse(' {% if 1 =! 2 %}ok{% endif %} ')
       end

test/integration/expression_test.rb

@@ -26,8 +26,12 @@ class ExpressionTest < Minitest::Test
   def test_float
     assert_template_result("-17.42", "{{ -17.42 }}")
     assert_template_result("2.5", "{{ 2.5 }}")
-    assert_expression_result(0.0, "0.....5")
-    assert_expression_result(0.0, "-0..1")
+
+    with_error_modes(:lax) do
+      assert_expression_result(0.0, "0.....5")
+      assert_expression_result(0.0, "-0..1")
+    end
+
     assert_expression_result(1.5, "1.5")
 
     # this is a unfortunate quirky behavior of Liquid
@@ -61,6 +65,7 @@ class ExpressionTest < Minitest::Test
     assert_template_result(
       "",
       "{{ - 'theme.css' - }}",
+      error_mode: :lax,
     )
   end
 
@@ -147,6 +152,35 @@ class ExpressionTest < Minitest::Test
     assert(parse_context.instance_variable_get(:@expression_cache).nil?)
   end
 
+  def test_safe_parse_with_variable_lookup
+    parse_context = Liquid::ParseContext.new
+    parser = parse_context.new_parser('product.title')
+    result = Liquid::Expression.safe_parse(parser)
+
+    assert_instance_of(Liquid::VariableLookup, result)
+    assert_equal('product', result.name)
+    assert_equal(['title'], result.lookups)
+  end
+
+  def test_safe_parse_with_number
+    parse_context = Liquid::ParseContext.new
+    parser = parse_context.new_parser('42')
+    result = Liquid::Expression.safe_parse(parser)
+
+    assert_equal(42, result)
+  end
+
+  def test_safe_parse_raises_syntax_error_for_invalid_expression
+    parse_context = Liquid::ParseContext.new
+    parser = parse_context.new_parser('')
+
+    error = assert_raises(Liquid::SyntaxError) do
+      Liquid::Expression.safe_parse(parser)
+    end
+
+    assert_match(/is not a valid expression/, error.message)
+  end
+
   private
 
   def assert_expression_result(expect, markup, **assigns)

test/integration/parsing_quirks_test.rb

@@ -31,18 +31,18 @@ class ParsingQuirksTest < Minitest::Test
   def test_error_on_empty_filter
     assert(Template.parse("{{test}}"))
 
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assert(Template.parse("{{|test}}"))
     end
 
-    with_error_mode(:strict) do
+    with_error_modes(:strict) do
       assert_raises(SyntaxError) { Template.parse("{{|test}}") }
       assert_raises(SyntaxError) { Template.parse("{{test |a|b|}}") }
     end
   end
 
   def test_meaningless_parens_error
-    with_error_mode(:strict) do
+    with_error_modes(:strict) do
       assert_raises(SyntaxError) do
         markup = "a == 'foo' or (b == 'bar' and c == 'baz') or false"
         Template.parse("{% if #{markup} %} YES {% endif %}")
@@ -51,7 +51,7 @@ class ParsingQuirksTest < Minitest::Test
   end
 
   def test_unexpected_characters_syntax_error
-    with_error_mode(:strict) do
+    with_error_modes(:strict) do
       assert_raises(SyntaxError) do
         markup = "true && false"
         Template.parse("{% if #{markup} %} YES {% endif %}")
@@ -70,7 +70,7 @@ class ParsingQuirksTest < Minitest::Test
   end
 
   def test_meaningless_parens_lax
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assigns = { 'b' => 'bar', 'c' => 'baz' }
       markup  = "a == 'foo' or (b == 'bar' and c == 'baz') or false"
       assert_template_result(' YES ', "{% if #{markup} %} YES {% endif %}", assigns)
@@ -78,7 +78,7 @@ class ParsingQuirksTest < Minitest::Test
   end
 
   def test_unexpected_characters_silently_eat_logic_lax
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       markup = "true && false"
       assert_template_result(' YES ', "{% if #{markup} %} YES {% endif %}")
       markup = "false || true"
@@ -93,7 +93,7 @@ class ParsingQuirksTest < Minitest::Test
   end
 
   def test_unanchored_filter_arguments
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assert_template_result('hi', "{{ 'hi there' | split$$$:' ' | first }}")
 
       assert_template_result('x', "{{ 'X' | downcase) }}")
@@ -106,14 +106,14 @@ class ParsingQuirksTest < Minitest::Test
   end
 
   def test_invalid_variables_work
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assert_template_result('bar', "{% assign 123foo = 'bar' %}{{ 123foo }}")
       assert_template_result('123', "{% assign 123 = 'bar' %}{{ 123 }}")
     end
   end
 
   def test_extra_dots_in_ranges
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assert_template_result('12345', "{% for i in (1...5) %}{{ i }}{% endfor %}")
     end
   end
@@ -133,7 +133,7 @@ class ParsingQuirksTest < Minitest::Test
   end
 
   def test_incomplete_expression
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assert_template_result("false", "{{ false - }}")
       assert_template_result("false", "{{ false > }}")
       assert_template_result("false", "{{ false < }}")

test/integration/standard_filter_test.rb

@@ -54,30 +54,6 @@ class TestEnumerable < Liquid::Drop
   end
 end
 
-class TestDeepEnumerable < Liquid::Drop
-  include Enumerable
-
-  class Product < Liquid::Drop
-    attr_reader :title, :price, :premium
-
-    def initialize(title:, price:, premium: nil)
-      @title = { "content" => title, "language" => "en" }
-      @price = { "value" => price, "unit" => "USD" }
-      @premium = { "category" => premium } if premium
-    end
-  end
-
-  def each(&block)
-    [
-      Product.new(title: "Pro goggles",    price: 1299),
-      Product.new(title: "Thermal gloves", price: 1299),
-      Product.new(title: "Alpine jacket",  price: 3999, premium: 'Basic'),
-      Product.new(title: "Mountain boots", price: 3899, premium: 'Pro'),
-      Product.new(title: "Safety helmet",  price: 1999)
-    ].each(&block)
-  end
-end
-
 class NumberLikeThing < Liquid::Drop
   def initialize(amount)
     @amount = amount
@@ -438,15 +414,6 @@ class StandardFiltersTest < Minitest::Test
     end
   end
 
-  def test_sort_natural_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | sort_natural: 'title.content' | map: 'title.content' | join: ', ' -}}
-    LIQUID
-    expected_output = "Alpine jacket, Mountain boots, Pro goggles, Safety helmet, Thermal gloves"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_legacy_sort_hash
     assert_equal([{ a: 1, b: 2 }], @filters.sort(a: 1, b: 2))
   end
@@ -483,15 +450,6 @@ class StandardFiltersTest < Minitest::Test
     end
   end
 
-  def test_uniq_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | uniq: 'price.value' | map: "title.content" | join: ', ' -}}
-    LIQUID
-    expected_output = "Pro goggles, Alpine jacket, Mountain boots, Safety helmet"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_compact_empty_array
     assert_equal([], @filters.compact([], "a"))
   end
@@ -508,15 +466,6 @@ class StandardFiltersTest < Minitest::Test
     end
   end
 
-  def test_compact_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | compact: 'premium.category' | map: 'title.content' | join: ', ' -}}
-    LIQUID
-    expected_output = "Alpine jacket, Mountain boots"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_reverse
     assert_equal([4, 3, 2, 1], @filters.reverse([1, 2, 3, 4]))
   end
@@ -611,12 +560,23 @@ class StandardFiltersTest < Minitest::Test
     end
   end
 
-  def test_map_returns_empty_with_no_property
+  def test_map_with_value_property
+    array = [
+      { "handle" => "alpha", "value" => "A" },
+      { "handle" => "beta", "value" => "B" },
+      { "handle" => "gamma", "value" => "C" }
+    ]
+
+    assert_template_result("A B C", "{{ array | map: 'value' | join: ' ' }}", { "array" => array })
+  end
+
+  def test_map_returns_input_with_no_property
     foo = [
       [1],
       [2],
       [3],
     ]
+
     assert_raises(Liquid::ArgumentError) do
       @filters.map(foo, nil)
     end
@@ -626,15 +586,6 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result("213", '{{ foo | sort: "bar" | map: "foo" }}', { "foo" => TestEnumerable.new })
   end
 
-  def test_sort_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | sort: 'price.value' | map: 'title.content' | join: ', ' -}}
-    LIQUID
-    expected_output = "Pro goggles, Thermal gloves, Safety helmet, Mountain boots, Alpine jacket"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_first_and_last_call_to_liquid
     assert_template_result('foobar', '{{ foo | first }}', { 'foo' => [ThingWithToLiquid.new] })
     assert_template_result('foobar', '{{ foo | last }}', { 'foo' => [ThingWithToLiquid.new] })
@@ -951,15 +902,6 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result(expected_output, template, { "array" => array })
   end
 
-  def test_reject_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | reject: 'title.content', 'Pro goggles' | map: 'price.value' | join: ', ' -}}
-    LIQUID
-    expected_output = "1299, 3999, 3899, 1999"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_has
     array = [
       { "handle" => "alpha", "ok" => true },
@@ -1028,16 +970,6 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result(expected_output, template, { "array" => array })
   end
 
-  def test_has_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | has: 'title.content', 'Pro goggles' -}},
-      {{- products | has: 'title.content', 'foo' -}}
-    LIQUID
-    expected_output = "true,false"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_find_with_value
     products = [
       { "title" => "Pro goggles",    "price" => 1299 },
@@ -1056,16 +988,6 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result(expected_output, template, { "products" => products })
   end
 
-  def test_find_with_deep_enumerables
-    template = <<~LIQUID
-      {%- assign product = products | find: 'title.content', 'Pro goggles' -%}
-      {{- product.title.content -}}
-    LIQUID
-    expected_output = "Pro goggles"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_find_with_empty_arrays
     template = <<~LIQUID
       {%- assign product = products | find: 'title.content', 'Not found' -%}
@@ -1096,16 +1018,6 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result(expected_output, template, { "products" => products })
   end
 
-  def test_find_index_with_deep_enumerables
-    template = <<~LIQUID
-      {%- assign index = products | find_index: 'title.content', 'Alpine jacket' -%}
-      {{- index -}}
-    LIQUID
-    expected_output = "2"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_find_index_with_empty_arrays
     template = <<~LIQUID
       {%- assign index = products | find_index: 'title.content', 'Not found' -%}
@@ -1132,6 +1044,23 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result(expected_output, template, { "array" => array })
   end
 
+  def test_where_with_empty_string_is_a_no_op
+    environment = { "array" => ["alpha", "beta", "gamma"] }
+    expected_output = "alpha beta gamma"
+    template = "{{ array | where: '' | join: ' ' }}"
+
+    assert_template_result(expected_output, template, environment)
+  end
+
+  def test_where_with_nil_is_a_no_op
+    environment = { "array" => ["alpha", "beta", "gamma"] }
+    template = "{{ array | where: nil | join: ' ' }}"
+
+    assert_raises(Liquid::ArgumentError) do
+      assert_template_result("alpha beta gamma", template, environment)
+    end
+  end
+
   def test_where_with_value
     array = [
       { "handle" => "alpha", "ok" => true },
@@ -1216,15 +1145,6 @@ class StandardFiltersTest < Minitest::Test
     assert_nil(@filters.where([nil], "ok"))
   end
 
-  def test_where_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | where: 'title.content', 'Pro goggles' | map: 'price.value' -}}
-    LIQUID
-    expected_output = "1299"
-
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
-  end
-
   def test_all_filters_never_raise_non_liquid_exception
     test_drop = TestDrop.new(value: "test")
     test_drop.context = Context.new
@@ -1376,101 +1296,31 @@ class StandardFiltersTest < Minitest::Test
     assert_template_result("0", "{{ input | sum: 'subtotal' }}", { "input" => input })
   end
 
-  def test_sum_with_deep_enumerables
-    template = <<~LIQUID
-      {{- products | sum: 'price.value' -}}
-    LIQUID
-    expected_output = "12495"
+  def test_sum_with_non_string_property
+    input = [{ true => 1 }, { 1.0 => 0.2, 1 => -0.3 }, { 1..5 => 0.4 }]
 
-    assert_template_result(expected_output, template, { "products" => TestDeepEnumerable.new })
+    assert_equal(1, @filters.sum(input, true))
+    assert_equal(0.2, @filters.sum(input, 1.0))
+    assert_equal(-0.3, @filters.sum(input, 1))
+    assert_equal(0.4, @filters.sum(input, (1..5)))
+    assert_equal(0, @filters.sum(input, nil))
+    assert_equal(0, @filters.sum(input, ""))
   end
 
-  def test_sort_with_different_types
-    input = [
-      { "price" => 1000 },
-      { "price" => :none },
-      { "price" => 3000 }
-    ]
+  def test_uniq_with_to_liquid_value
+    input = [StringDrop.new("foo"), StringDrop.new("bar"), "foo"]
+    expected = [StringDrop.new("foo"), StringDrop.new("bar")]
+    result = @filters.uniq(input)
 
-    assert_raises(Liquid::ArgumentError) do
-      @filters.sort(input, "price")
-    end
+    assert_equal(expected, result)
   end
 
-  def test_sort_with_nested_different_types
-    input = [
-      { "price" => { "value" => 1000, "unit" => "BRL" } },
-      { "price" => { "value" => 2000, "unit" => nil } },
-      { "price" => { "value" => 3000, "unit" => :none } }
-    ]
-    expected_output = "2000, 1000, 3000"
-    template = <<~LIQUID
-      {{- input | sort: 'price.unit' | map: 'price.value' | join: ', ' -}}
-    LIQUID
+  def test_uniq_with_to_liquid_value_pick_correct_classes
+    input = ["foo", StringDrop.new("foo"), StringDrop.new("bar")]
+    expected = [String, StringDrop]
+    result = @filters.uniq(input).map(&:class)
 
-    assert_template_result(expected_output, template, { "input" => input })
-  end
-
-  def test_sort_natural_with_nested_different_types
-    input = [
-      { "price" => { "value" => 1000, "unit" => "brl" } },
-      { "price" => { "value" => 2000, "unit" => "BRL" } },
-      { "price" => { "value" => 3000, "unit" => nil } },
-      { "price" => { "value" => 4000, "unit" => :brl } }
-    ]
-    expected_output = "1000, 2000, 4000, 3000"
-    template = <<~LIQUID
-      {{- input | sort_natural: 'price.unit' | map: 'price.value' | join: ', ' -}}
-    LIQUID
-
-    assert_template_result(expected_output, template, { "input" => input })
-  end
-
-  def test_uniq_with_nested_different_types
-    input = [
-      { "price" => { "value" => 1000, "unit" => "BRL" } },
-      { "price" => { "value" => 2000, "unit" => "BRL" } },
-      { "price" => { "value" => 3000, "unit" => :USD } },
-      { "price" => { "value" => 4000, "unit" => :BRL } },
-      { "price" => { "value" => 5000, "unit" => nil } }
-    ]
-
-    expected_output = "BRL, USD, BRL, " # Uniq handles different types uniqueness
-    template = <<~LIQUID
-      {{- input | uniq: 'price.unit' | map: 'price.unit' | join: ', ' -}}
-    LIQUID
-
-    assert_template_result(expected_output, template, { "input" => input })
-  end
-
-  def test_map_with_nested_different_types
-    input = [
-      { "price" => { "value" => 1000, "unit" => "brl" } },
-      { "price" => { "value" => 2000, "unit" => "BRL" } },
-      { "price" => { "value" => 3000, "unit" => nil } },
-      { "price" => { "value" => 4000, "unit" => :brl } }
-    ]
-    expected_output = "brl, BRL, , brl"
-    template = <<~LIQUID
-      {{- input | map: 'price.unit'| join: ', ' -}}
-    LIQUID
-
-    assert_template_result(expected_output, template, { "input" => input })
-  end
-
-  def test_sum_with_nested_different_types
-    input = [
-      { "price" => { "value" => 1000 } },
-      { "price" => { "value" => nil } },
-      { "price" => { "value" => :none } },
-      { "price" => { "value" => 3000 } }
-    ]
-    expected_output = "4000"
-    template = <<~LIQUID
-      {{- input | sum: 'price.value' -}}
-    LIQUID
-
-    assert_template_result(expected_output, template, { "input" => input })
+    assert_equal(expected, result)
   end
 
   private

test/integration/tags/cycle_tag_test.rb

@@ -3,20 +3,10 @@
 require 'test_helper'
 
 class CycleTagTest < Minitest::Test
-  def test_simple_cycle
-    template = <<~LIQUID
-      {%- cycle '1', '2', '3' -%}
-      {%- cycle '1', '2', '3' -%}
-      {%- cycle '1', '2', '3' -%}
-    LIQUID
-
-    assert_template_result("123", template)
-  end
-
   def test_simple_cycle_inside_for_loop
     template = <<~LIQUID
       {%- for i in (1..3) -%}
-        {% cycle '1', '2', '3' %}
+        {%- cycle '1', '2', '3' -%}
       {%- endfor -%}
     LIQUID
 
@@ -36,13 +26,157 @@ class CycleTagTest < Minitest::Test
     assert_template_result("123", template)
   end
 
-  def test_cycle_tag_always_resets_cycle
+  def test_cycle_named_groups_string
     template = <<~LIQUID
-      {%- assign a = "1" -%}
-      {%- cycle a, "2" -%}
-      {%- cycle a, "2" -%}
+      {%- for i in (1..3) -%}
+        {%- cycle 'placeholder1': 1, 2, 3 -%}
+        {%- cycle 'placeholder2': 1, 2, 3 -%}
+      {%- endfor -%}
     LIQUID
 
-    assert_template_result("11", template)
+    assert_template_result("112233", template)
+  end
+
+  def test_cycle_named_groups_vlookup
+    template = <<~LIQUID
+      {%- assign placeholder1 = 'placeholder1' -%}
+      {%- assign placeholder2 = 'placeholder2' -%}
+      {%- for i in (1..3) -%}
+        {%- cycle placeholder1: 1, 2, 3 -%}
+        {%- cycle placeholder2: 1, 2, 3 -%}
+      {%- endfor -%}
+    LIQUID
+
+    assert_template_result("112233", template)
+  end
+
+  def test_unnamed_cycle_have_independent_counters_when_used_with_lookups
+    template = <<~LIQUID
+      {%- assign a = "1" -%}
+      {%- for i in (1..3) -%}
+        {%- cycle a, "2" -%}
+        {%- cycle a, "2" -%}
+      {%- endfor -%}
+    LIQUID
+
+    assert_template_result("112211", template)
+  end
+
+  def test_unnamed_cycle_dependent_counter_when_used_with_literal_values
+    template = <<~LIQUID
+      {%- cycle "1", "2" -%}
+      {%- cycle "1", "2" -%}
+      {%- cycle "1", "2" -%}
+    LIQUID
+
+    assert_template_result("121", template)
+  end
+
+  def test_optional_trailing_comma
+    template = <<~LIQUID
+      {%- cycle "1", "2", -%}
+      {%- cycle "1", "2", -%}
+      {%- cycle "1", "2", -%}
+      {%- cycle "1", -%}
+    LIQUID
+
+    assert_template_result("1211", template)
+  end
+
+  def test_cycle_tag_without_arguments
+    error = assert_raises(Liquid::SyntaxError) do
+      Template.parse("{% cycle %}")
+    end
+
+    assert_match(/Syntax Error in 'cycle' - Valid syntax: cycle \[name :\] var/, error.message)
+  end
+
+  def test_cycle_tag_with_error_mode
+    # QuotedFragment is more permissive than what Parser#expression allows.
+    template1 = "{% assign 5 = 'b' %}{% cycle .5, .4 %}"
+    template2 = "{% cycle .5: 'a', 'b' %}"
+
+    with_error_modes(:lax, :strict) do
+      assert_template_result("b", template1)
+      assert_template_result("a", template2)
+    end
+
+    with_error_modes(:rigid) do
+      error1 = assert_raises(Liquid::SyntaxError) { Template.parse(template1) }
+      error2 = assert_raises(Liquid::SyntaxError) { Template.parse(template2) }
+
+      expected_error = /Liquid syntax error: \[:dot, "."\] is not a valid expression/
+
+      assert_match(expected_error, error1.message)
+      assert_match(expected_error, error2.message)
+    end
+  end
+
+  def test_cycle_with_trailing_elements
+    assignments = "{% assign a = 'A' %}{% assign n = 'N' %}"
+
+    template1 = "#{assignments}{% cycle       'a'  'b', 'c' %}"
+    template2 = "#{assignments}{% cycle name: 'a'  'b', 'c' %}"
+    template3 = "#{assignments}{% cycle name: 'a', 'b'  'c' %}"
+    template4 = "#{assignments}{% cycle n  e: 'a', 'b', 'c' %}"
+    template5 = "#{assignments}{% cycle n  e  'a', 'b', 'c' %}"
+
+    with_error_modes(:lax, :strict) do
+      assert_template_result("a", template1)
+      assert_template_result("a", template2)
+      assert_template_result("a", template3)
+      assert_template_result("N", template4)
+      assert_template_result("N", template5)
+    end
+
+    with_error_modes(:rigid) do
+      error1 = assert_raises(Liquid::SyntaxError) { Template.parse(template1) }
+      error2 = assert_raises(Liquid::SyntaxError) { Template.parse(template2) }
+      error3 = assert_raises(Liquid::SyntaxError) { Template.parse(template3) }
+      error4 = assert_raises(Liquid::SyntaxError) { Template.parse(template4) }
+      error5 = assert_raises(Liquid::SyntaxError) { Template.parse(template5) }
+
+      expected_error = /Expected end_of_string but found/
+
+      assert_match(expected_error, error1.message)
+      assert_match(expected_error, error2.message)
+      assert_match(expected_error, error3.message)
+      assert_match(expected_error, error4.message)
+      assert_match(expected_error, error5.message)
+    end
+  end
+
+  def test_cycle_name_with_invalid_expression
+    template = <<~LIQUID
+      {% for i in (1..3) %}
+        {% cycle foo=>bar: "a", "b" %}
+      {% endfor %}
+    LIQUID
+
+    with_error_modes(:lax, :strict) do
+      refute_nil(Template.parse(template))
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
+
+  def test_cycle_variable_with_invalid_expression
+    template = <<~LIQUID
+      {% for i in (1..3) %}
+        {% cycle foo=>bar, "a", "b" %}
+      {% endfor %}
+    LIQUID
+
+    with_error_modes(:lax, :strict) do
+      refute_nil(Template.parse(template))
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
   end
 end

test/integration/tags/include_tag_test.rb

@@ -204,6 +204,32 @@ class IncludeTagTest < Minitest::Test
     )
   end
 
+  def test_rigid_parsing_errors
+    with_error_modes(:lax, :strict) do
+      assert_template_result(
+        'hello value1 value2',
+        '{% include "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
+        partials: { 'snippet' => 'hello {{ arg1 }} {{ arg2 }}' },
+      )
+    end
+
+    with_error_modes(:rigid) do
+      assert_syntax_error(
+        '{% include "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
+      )
+      assert_syntax_error(
+        '{% include "snippet" | filter %}',
+      )
+    end
+  end
+
+  def test_optional_commas
+    partials = { 'snippet' => 'hello {{ arg1 }} {{ arg2 }}' }
+    assert_template_result('hello value1 value2', '{% include "snippet", arg1: "value1", arg2: "value2" %}', partials: partials)
+    assert_template_result('hello value1 value2', '{% include "snippet"  arg1: "value1", arg2: "value2" %}', partials: partials)
+    assert_template_result('hello value1 value2', '{% include "snippet"  arg1: "value1"  arg2: "value2" %}', partials: partials)
+  end
+
   def test_include_tag_caches_second_read_of_same_partial
     file_system = CountingFileSystem.new
     environment = Liquid::Environment.build(file_system: file_system)
@@ -277,13 +303,13 @@ class IncludeTagTest < Minitest::Test
     assert_raises(Liquid::SyntaxError) do
       Template.parse("{% include template %}", error_mode: :strict, environment: env).render!("template" => '{{ "X" || downcase }}')
     end
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assert_equal('x', Template.parse("{% include template %}", error_mode: :strict, include_options_blacklist: true, environment: env).render!("template" => '{{ "X" || downcase }}'))
     end
     assert_raises(Liquid::SyntaxError) do
       Template.parse("{% include template %}", error_mode: :strict, include_options_blacklist: [:locale], environment: env).render!("template" => '{{ "X" || downcase }}')
     end
-    with_error_mode(:lax) do
+    with_error_modes(:lax) do
       assert_equal('x', Template.parse("{% include template %}", error_mode: :strict, include_options_blacklist: [:error_mode], environment: env).render!("template" => '{{ "X" || downcase }}'))
     end
   end
@@ -374,4 +400,43 @@ class IncludeTagTest < Minitest::Test
       render_errors: true,
     )
   end
+
+  def test_include_template_with_invalid_expression
+    template = "{% include foo=>bar %}"
+
+    with_error_modes(:lax, :strict) do
+      refute_nil(Template.parse(template))
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
+
+  def test_include_with_invalid_expression
+    template = '{% include "snippet" with foo=>bar %}'
+
+    with_error_modes(:lax, :strict) do
+      refute_nil(Template.parse(template))
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
+
+  def test_include_attribute_with_invalid_expression
+    template = '{% include "snippet", key: foo=>bar %}'
+
+    with_error_modes(:lax, :strict) do
+      refute_nil(Template.parse(template))
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
 end # IncludeTagTest

test/integration/tags/render_tag_test.rb

@@ -105,7 +105,33 @@ class RenderTagTest < Minitest::Test
     assert_syntax_error("{% assign name = 'snippet' %}{% render name %}")
   end
 
-  def test_include_tag_caches_second_read_of_same_partial
+  def test_rigid_parsing_errors
+    with_error_modes(:lax, :strict) do
+      assert_template_result(
+        'hello value1 value2',
+        '{% render "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
+        partials: { 'snippet' => 'hello {{ arg1 }} {{ arg2 }}' },
+      )
+    end
+
+    with_error_modes(:rigid) do
+      assert_syntax_error(
+        '{% render "snippet" !!! arg1: "value1" ~~~ arg2: "value2" %}',
+      )
+      assert_syntax_error(
+        '{% render "snippet" | filter %}',
+      )
+    end
+  end
+
+  def test_optional_commas
+    partials = { 'snippet' => 'hello {{ arg1 }} {{ arg2 }}' }
+    assert_template_result('hello value1 value2', '{% render "snippet", arg1: "value1", arg2: "value2" %}', partials: partials)
+    assert_template_result('hello value1 value2', '{% render "snippet"  arg1: "value1", arg2: "value2" %}', partials: partials)
+    assert_template_result('hello value1 value2', '{% render "snippet"  arg1: "value1"  arg2: "value2" %}', partials: partials)
+  end
+
+  def test_render_tag_caches_second_read_of_same_partial
     file_system = StubFileSystem.new('snippet' => 'echo')
     assert_equal(
       'echoecho',
@@ -288,4 +314,30 @@ class RenderTagTest < Minitest::Test
       render_errors: true,
     )
   end
+
+  def test_render_with_invalid_expression
+    template = '{% render "snippet" with foo=>bar %}'
+
+    with_error_modes(:lax, :strict) do
+      refute_nil(Template.parse(template))
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
+
+  def test_render_attribute_with_invalid_expression
+    template = '{% render "snippet", key: foo=>bar %}'
+
+    with_error_modes(:lax, :strict) do
+      refute_nil(Template.parse(template))
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
 end

test/integration/tags/table_row_test.rb

@@ -138,7 +138,7 @@ class TableRowTest < Minitest::Test
 
   def test_tablerow_loop_drop_attributes
     template = <<~LIQUID.chomp
-      {% tablerow i in (1...2) %}
+      {% tablerow i in (1..2) %}
       col: {{ tablerowloop.col }}
       col0: {{ tablerowloop.col0 }}
       col_first: {{ tablerowloop.col_first }}
@@ -192,12 +192,14 @@ class TableRowTest < Minitest::Test
     assert_template_result(
       "Liquid error (line 1): invalid integer",
       '{% tablerow n in (1...10) limit:true %} {{n}} {% endtablerow %}',
+      error_mode: :warn,
       render_errors: true,
     )
 
     assert_template_result(
       "Liquid error (line 1): invalid integer",
       '{% tablerow n in (1...10) offset:true %} {{n}} {% endtablerow %}',
+      error_mode: :warn,
       render_errors: true,
     )
 
@@ -205,18 +207,19 @@ class TableRowTest < Minitest::Test
       "Liquid error (line 1): invalid integer",
       '{% tablerow n in (1...10) cols:true %} {{n}} {% endtablerow %}',
       render_errors: true,
+      error_mode: :warn,
     )
   end
 
   def test_table_row_handles_interrupts
     assert_template_result(
       "<tr class=\"row1\">\n<td class=\"col1\"> 1 </td></tr>\n",
-      '{% tablerow n in (1...3) cols:2 %} {{n}} {% break %} {{n}} {% endtablerow %}',
+      '{% tablerow n in (1..3) cols:2 %} {{n}} {% break %} {{n}} {% endtablerow %}',
     )
 
     assert_template_result(
       "<tr class=\"row1\">\n<td class=\"col1\"> 1 </td><td class=\"col2\"> 2 </td></tr>\n<tr class=\"row2\"><td class=\"col1\"> 3 </td></tr>\n",
-      '{% tablerow n in (1...3) cols:2 %} {{n}} {% continue %} {{n}} {% endtablerow %}',
+      '{% tablerow n in (1..3) cols:2 %} {{n}} {% continue %} {{n}} {% endtablerow %}',
     )
   end
 
@@ -255,4 +258,211 @@ class TableRowTest < Minitest::Test
       template,
     )
   end
+
+  def test_tablerow_with_cols_attribute_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow i in (1..6) cols: 3 %}{{ i }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">1</td><td class="col2">2</td><td class="col3">3</td></tr>
+      <tr class="row2"><td class="col1">4</td><td class="col2">5</td><td class="col3">6</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template)
+    end
+  end
+
+  def test_tablerow_with_limit_attribute_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow i in (1..10) limit: 3 %}{{ i }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">1</td><td class="col2">2</td><td class="col3">3</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template)
+    end
+  end
+
+  def test_tablerow_with_offset_attribute_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow i in (1..5) offset: 2 %}{{ i }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">3</td><td class="col2">4</td><td class="col3">5</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template)
+    end
+  end
+
+  def test_tablerow_with_range_attribute_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow i in (1..3) range: (1..10) %}{{ i }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">1</td><td class="col2">2</td><td class="col3">3</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template)
+    end
+  end
+
+  def test_tablerow_with_multiple_attributes_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow i in (1..10) cols: 2, limit: 4, offset: 1 %}{{ i }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">2</td><td class="col2">3</td></tr>
+      <tr class="row2"><td class="col1">4</td><td class="col2">5</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template)
+    end
+  end
+
+  def test_tablerow_with_variable_collection_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow n in numbers cols: 2 %}{{ n }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">1</td><td class="col2">2</td></tr>
+      <tr class="row2"><td class="col1">3</td><td class="col2">4</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template, { 'numbers' => [1, 2, 3, 4] })
+    end
+  end
+
+  def test_tablerow_with_dotted_access_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow n in obj.numbers cols: 2 %}{{ n }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">1</td><td class="col2">2</td></tr>
+      <tr class="row2"><td class="col1">3</td><td class="col2">4</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template, { 'obj' => { 'numbers' => [1, 2, 3, 4] } })
+    end
+  end
+
+  def test_tablerow_with_bracketed_access_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow n in obj["numbers"] cols: 2 %}{{ n }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">10</td><td class="col2">20</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template, { 'obj' => { 'numbers' => [10, 20] } })
+    end
+  end
+
+  def test_tablerow_without_attributes_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow i in (1..3) %}{{ i }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">1</td><td class="col2">2</td><td class="col3">3</td></tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template)
+    end
+  end
+
+  def test_tablerow_without_in_keyword_in_rigid_mode
+    template = '{% tablerow i (1..10) %}{{ i }}{% endtablerow %}'
+
+    with_error_modes(:rigid) do
+      error = assert_raises(SyntaxError) { Template.parse(template) }
+      assert_equal("Liquid syntax error: For loops require an 'in' clause in \"i (1..10)\"", error.message)
+    end
+  end
+
+  def test_tablerow_with_multiple_invalid_attributes_reports_first_in_rigid_mode
+    template = '{% tablerow i in (1..10) invalid1: 5, invalid2: 10 %}{{ i }}{% endtablerow %}'
+
+    with_error_modes(:rigid) do
+      error = assert_raises(SyntaxError) { Template.parse(template) }
+      assert_equal("Liquid syntax error: Invalid attribute 'invalid1' in tablerow loop. Valid attributes are cols, limit, offset, and range in \"i in (1..10) invalid1: 5, invalid2: 10\"", error.message)
+    end
+  end
+
+  def test_tablerow_with_empty_collection_in_rigid_mode
+    template = <<~LIQUID.chomp
+      {% tablerow i in empty_array cols: 2 %}{{ i }}{% endtablerow %}
+    LIQUID
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      </tr>
+    OUTPUT
+
+    with_error_modes(:rigid) do
+      assert_template_result(expected, template, { 'empty_array' => [] })
+    end
+  end
+
+  def test_tablerow_with_invalid_attribute_strict_vs_rigid
+    template = '{% tablerow i in (1..5) invalid_attr: 10 %}{{ i }}{% endtablerow %}'
+
+    expected = <<~OUTPUT
+      <tr class="row1">
+      <td class="col1">1</td><td class="col2">2</td><td class="col3">3</td><td class="col4">4</td><td class="col5">5</td></tr>
+    OUTPUT
+
+    with_error_modes(:lax, :strict) do
+      assert_template_result(expected, template)
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(SyntaxError) { Template.parse(template) }
+      assert_match(/Invalid attribute 'invalid_attr'/, error.message)
+    end
+  end
+
+  def test_tablerow_with_invalid_expression_strict_vs_rigid
+    template = '{% tablerow i in (1..5) limit: foo=>bar %}{{ i }}{% endtablerow %}'
+
+    with_error_modes(:lax, :strict) do
+      expected = <<~OUTPUT
+        <tr class="row1">
+        </tr>
+      OUTPUT
+      assert_template_result(expected, template)
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(SyntaxError) { Template.parse(template) }
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
 end

test/integration/variable_test.rb

@@ -209,4 +209,69 @@ class VariableTest < Minitest::Test
       end
     end
   end
+
+  def test_filter_with_single_trailing_comma
+    template = '{{ "hello" | append: "world", }}'
+
+    with_error_modes(:strict) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/is not a valid expression/, error.message)
+    end
+
+    with_error_modes(:rigid) do
+      assert_template_result('helloworld', template)
+    end
+  end
+
+  def test_multiple_filters_with_trailing_commas
+    template = '{{ "hello" | append: "1", | append: "2", }}'
+
+    with_error_modes(:strict) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/is not a valid expression/, error.message)
+    end
+
+    with_error_modes(:rigid) do
+      assert_template_result('hello12', template)
+    end
+  end
+
+  def test_filter_with_colon_but_no_arguments
+    template = '{{ "test" | upcase: }}'
+
+    with_error_modes(:strict) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/is not a valid expression/, error.message)
+    end
+
+    with_error_modes(:rigid) do
+      assert_template_result('TEST', template)
+    end
+  end
+
+  def test_filter_chain_with_colon_no_args
+    template = '{{ "test" | append: "x" | upcase: }}'
+
+    with_error_modes(:strict) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/is not a valid expression/, error.message)
+    end
+
+    with_error_modes(:rigid) do
+      assert_template_result('TESTX', template)
+    end
+  end
+
+  def test_combining_trailing_comma_and_empty_args
+    template = '{{ "test" | append: "x", | upcase: }}'
+
+    with_error_modes(:strict) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+      assert_match(/is not a valid expression/, error.message)
+    end
+
+    with_error_modes(:rigid) do
+      assert_template_result('TESTX', template)
+    end
+  end
 end

test/test_helper.rb

@@ -34,7 +34,7 @@ module Minitest
 
     def assert_template_result(
       expected, template, assigns = {},
-      message: nil, partials: nil, error_mode: nil, render_errors: false,
+      message: nil, partials: nil, error_mode: Liquid::Environment.default.error_mode, render_errors: false,
       template_factory: nil
     )
       file_system = StubFileSystem.new(partials || {})
@@ -82,10 +82,12 @@ module Minitest
       Environment.dangerously_override(environment, &blk)
     end
 
-    def with_error_mode(mode)
+    def with_error_modes(*modes)
       old_mode = Liquid::Environment.default.error_mode
-      Liquid::Environment.default.error_mode = mode
-      yield
+      modes.each do |mode|
+        Liquid::Environment.default.error_mode = mode
+        yield
+      end
     ensure
       Liquid::Environment.default.error_mode = old_mode
     end
@@ -146,6 +148,35 @@ class BooleanDrop < Liquid::Drop
   end
 end
 
+class StringDrop < Liquid::Drop
+  include Comparable
+
+  def initialize(value)
+    super()
+    @value = value
+  end
+
+  def to_liquid_value
+    @value
+  end
+
+  def to_s
+    @value
+  end
+
+  def to_str
+    @value
+  end
+
+  def inspect
+    "#<StringDrop @value=#{@value.inspect}>"
+  end
+
+  def <=>(other)
+    to_liquid_value <=> Liquid::Utils.to_liquid_value(other)
+  end
+end
+
 class ErrorDrop < Liquid::Drop
   def standard_error
     raise Liquid::StandardError, 'standard error'

test/unit/block_unit_test.rb

@@ -47,12 +47,18 @@ class BlockUnitTest < Minitest::Test
     )
   end
 
-  def test_with_block
+  def test_comment_tag_with_block
     template = Liquid::Template.parse("  {% comment %} {% endcomment %} ")
     assert_equal([String, Comment, String], block_types(template.root.nodelist))
     assert_equal(3, template.root.nodelist.size)
   end
 
+  def test_doc_tag_with_block
+    template = Liquid::Template.parse("  {% doc %} {% enddoc %} ")
+    assert_equal([String, Doc, String], block_types(template.root.nodelist))
+    assert_equal(3, template.root.nodelist.size)
+  end
+
   private
 
   def block_types(nodelist)

test/unit/condition_unit_test.rb

@@ -166,6 +166,37 @@ class ConditionUnitTest < Minitest::Test
     assert_includes(err.lines.map(&:strip), expected)
   end
 
+  def test_parse_expression_in_strict_mode
+    environment = Environment.build(error_mode: :strict)
+    parse_context = ParseContext.new(environment: environment)
+    result = Condition.parse_expression(parse_context, 'product.title')
+
+    assert_instance_of(VariableLookup, result)
+    assert_equal('product', result.name)
+    assert_equal(['title'], result.lookups)
+  end
+
+  def test_parse_expression_in_rigid_mode_raises_internal_error
+    environment = Environment.build(error_mode: :rigid)
+    parse_context = ParseContext.new(environment: environment)
+
+    error = assert_raises(Liquid::InternalError) do
+      Condition.parse_expression(parse_context, 'product.title')
+    end
+
+    assert_match(/unsafe parse_expression cannot be used in rigid mode/, error.message)
+  end
+
+  def test_parse_expression_with_safe_true_in_rigid_mode
+    environment = Environment.build(error_mode: :rigid)
+    parse_context = ParseContext.new(environment: environment)
+    result = Condition.parse_expression(parse_context, 'product.title', safe: true)
+
+    assert_instance_of(VariableLookup, result)
+    assert_equal('product', result.name)
+    assert_equal(['title'], result.lookups)
+  end
+
   private
 
   def assert_evaluates_true(left, op, right)

test/unit/environment_test.rb

@@ -0,0 +1,25 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class EnvironmentTest < Minitest::Test
+  include Liquid
+
+  class UnsubscribeFooter < Liquid::Tag
+    def render(_context)
+      'Unsubscribe Footer'
+    end
+  end
+
+  def test_custom_tag
+    email_environment = Liquid::Environment.build do |environment|
+      environment.register_tag("unsubscribe_footer", UnsubscribeFooter)
+    end
+
+    assert(email_environment.tags["unsubscribe_footer"])
+    assert(email_environment.tag_for_name("unsubscribe_footer"))
+    template = Liquid::Template.parse("{% unsubscribe_footer %}", environment: email_environment)
+
+    assert_equal('Unsubscribe Footer', template.render)
+  end
+end

test/unit/lexer_unit_test.rb

@@ -131,6 +131,16 @@ class LexerUnitTest < Minitest::Test
     assert_equal([[:id, "false"], [:number, "1"], [:end_of_string]], tokenize("false 1"))
   end
 
+  def test_error_with_invalid_utf8
+    error = assert_raises(SyntaxError) do
+      tokenize("\x00\xff")
+    end
+    assert_equal(
+      'Liquid syntax error: Invalid byte sequence in UTF-8',
+      error.message,
+    )
+  end
+
   private
 
   def tokenize(input)

test/unit/parse_context_unit_test.rb

@@ -0,0 +1,123 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class ParseContextUnitTest < Minitest::Test
+  include Liquid
+
+  def test_safe_parse_expression_with_variable_lookup
+    parser_strict = strict_parse_context.new_parser('product.title')
+    result_strict = strict_parse_context.safe_parse_expression(parser_strict)
+
+    parser_rigid = rigid_parse_context.new_parser('product.title')
+    result_rigid = rigid_parse_context.safe_parse_expression(parser_rigid)
+
+    assert_instance_of(VariableLookup, result_strict)
+    assert_equal('product', result_strict.name)
+    assert_equal(['title'], result_strict.lookups)
+
+    assert_instance_of(VariableLookup, result_rigid)
+    assert_equal('product', result_rigid.name)
+    assert_equal(['title'], result_rigid.lookups)
+  end
+
+  def test_safe_parse_expression_raises_syntax_error_for_invalid_expression
+    parser_strict = strict_parse_context.new_parser('')
+    parser_rigid = rigid_parse_context.new_parser('')
+
+    error_strict = assert_raises(Liquid::SyntaxError) do
+      strict_parse_context.safe_parse_expression(parser_strict)
+    end
+    assert_match(/is not a valid expression/, error_strict.message)
+
+    error_rigid = assert_raises(Liquid::SyntaxError) do
+      rigid_parse_context.safe_parse_expression(parser_rigid)
+    end
+
+    assert_match(/is not a valid expression/, error_rigid.message)
+  end
+
+  def test_parse_expression_with_variable_lookup
+    result_strict = strict_parse_context.parse_expression('product.title')
+
+    assert_instance_of(VariableLookup, result_strict)
+    assert_equal('product', result_strict.name)
+    assert_equal(['title'], result_strict.lookups)
+
+    error = assert_raises(Liquid::InternalError) do
+      rigid_parse_context.parse_expression('product.title')
+    end
+
+    assert_match(/unsafe parse_expression cannot be used in rigid mode/, error.message)
+  end
+
+  def test_parse_expression_with_safe_true
+    result_strict = strict_parse_context.parse_expression('product.title', safe: true)
+
+    assert_instance_of(VariableLookup, result_strict)
+    assert_equal('product', result_strict.name)
+    assert_equal(['title'], result_strict.lookups)
+
+    result_rigid = rigid_parse_context.parse_expression('product.title', safe: true)
+
+    assert_instance_of(VariableLookup, result_rigid)
+    assert_equal('product', result_rigid.name)
+    assert_equal(['title'], result_rigid.lookups)
+  end
+
+  def test_parse_expression_with_empty_string
+    result_strict = strict_parse_context.parse_expression('')
+    assert_nil(result_strict)
+
+    error = assert_raises(Liquid::InternalError) do
+      rigid_parse_context.parse_expression('')
+    end
+
+    assert_match(/unsafe parse_expression cannot be used in rigid mode/, error.message)
+  end
+
+  def test_parse_expression_with_empty_string_and_safe_true
+    result_strict = strict_parse_context.parse_expression('', safe: true)
+    assert_nil(result_strict)
+
+    result_rigid = rigid_parse_context.parse_expression('', safe: true)
+    assert_nil(result_rigid)
+  end
+
+  def test_safe_parse_expression_advances_parser_pointer
+    parser = rigid_parse_context.new_parser('foo, bar')
+
+    # safe_parse_expression consumes "foo"
+    first_result = rigid_parse_context.safe_parse_expression(parser)
+    assert_instance_of(VariableLookup, first_result)
+    assert_equal('foo', first_result.name)
+
+    parser.consume(:comma)
+
+    # safe_parse_expression consumes "bar"
+    second_result = rigid_parse_context.safe_parse_expression(parser)
+    assert_instance_of(VariableLookup, second_result)
+    assert_equal('bar', second_result.name)
+
+    parser.consume(:end_of_string)
+  end
+
+  def test_parse_expression_with_whitespace_in_rigid_mode
+    result = rigid_parse_context.parse_expression('   ', safe: true)
+    assert_nil(result)
+  end
+
+  private
+
+  def strict_parse_context
+    @strict_parse_context ||= ParseContext.new(
+      environment: Environment.build(error_mode: :strict),
+    )
+  end
+
+  def rigid_parse_context
+    @rigid_parse_context ||= ParseContext.new(
+      environment: Environment.build(error_mode: :rigid),
+    )
+  end
+end

test/unit/partial_cache_unit_test.rb

@@ -184,7 +184,7 @@ class PartialCacheUnitTest < Minitest::Test
       },
     )
 
-    [:lax, :warn, :strict].each do |error_mode|
+    [:lax, :warn, :strict, :rigid].each do |error_mode|
       Liquid::PartialCache.load(
         'my_partial',
         context: context,
@@ -193,7 +193,7 @@ class PartialCacheUnitTest < Minitest::Test
     end
 
     assert_equal(
-      ["my_partial:lax", "my_partial:warn", "my_partial:strict"],
+      ["my_partial:lax", "my_partial:warn", "my_partial:strict", "my_partial:rigid"],
       context.registers[:cached_partials].keys,
     )
   end

test/unit/tags/case_tag_unit_test.rb

@@ -9,4 +9,120 @@ class CaseTagUnitTest < Minitest::Test
     template = Liquid::Template.parse('{% case var %}{% when true %}WHEN{% else %}ELSE{% endcase %}')
     assert_equal(['WHEN', 'ELSE'], template.root.nodelist[0].nodelist.map(&:nodelist).flatten)
   end
+
+  def test_case_with_trailing_element
+    template = <<~LIQUID
+      {%- case 1 bar -%}
+        {%- when 1 -%}
+          one
+        {%- else -%}
+          two
+      {%- endcase -%}
+    LIQUID
+
+    with_error_modes(:lax, :strict) do
+      assert_template_result("one", template)
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+
+      assert_match(/Expected end_of_string but found/, error.message)
+    end
+  end
+
+  def test_case_when_with_trailing_element
+    template = <<~LIQUID
+      {%- case 1 -%}
+        {%- when 1 bar -%}
+          one
+        {%- else -%}
+          two
+      {%- endcase -%}
+    LIQUID
+
+    with_error_modes(:lax, :strict) do
+      assert_template_result("one", template)
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+
+      assert_match(/Expected end_of_string but found/, error.message)
+    end
+  end
+
+  def test_case_when_with_comma
+    template = <<~LIQUID
+      {%- case 1 -%}
+        {%- when 2, 1 -%}
+          one
+        {%- else -%}
+          two
+      {%- endcase -%}
+    LIQUID
+
+    with_error_modes(:lax, :strict, :rigid) do
+      assert_template_result("one", template)
+    end
+  end
+
+  def test_case_when_with_or
+    template = <<~LIQUID
+      {%- case 1 -%}
+        {%- when 2 or 1 -%}
+          one
+        {%- else -%}
+          two
+      {%- endcase -%}
+    LIQUID
+
+    with_error_modes(:lax, :strict, :rigid) do
+      assert_template_result("one", template)
+    end
+  end
+
+  def test_case_with_invalid_expression
+    template = <<~LIQUID
+      {%- case foo=>bar -%}
+        {%- when 'baz' -%}
+          one
+        {%- else -%}
+          two
+      {%- endcase -%}
+    LIQUID
+    assigns = { 'foo' => { 'bar' => 'baz' } }
+
+    with_error_modes(:lax, :strict) do
+      assert_template_result("one", template, assigns)
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
+
+  def test_case_when_with_invalid_expression
+    template = <<~LIQUID
+      {%- case 'baz' -%}
+        {%- when foo=>bar -%}
+          one
+        {%- else -%}
+          two
+      {%- endcase -%}
+    LIQUID
+    assigns = { 'foo' => { 'bar' => 'baz' } }
+
+    with_error_modes(:lax, :strict) do
+      assert_template_result("one", template, assigns)
+    end
+
+    with_error_modes(:rigid) do
+      error = assert_raises(Liquid::SyntaxError) { Template.parse(template) }
+
+      assert_match(/Unexpected character =/, error.message)
+    end
+  end
 end

test/unit/tags/doc_tag_unit_test.rb

@@ -0,0 +1,287 @@
+# frozen_string_literal: true
+
+require 'test_helper'
+
+class DocTagUnitTest < Minitest::Test
+  def test_doc_tag
+    template = <<~LIQUID.chomp
+      {% doc %}
+        Renders loading-spinner.
+
+        @param {string} foo - some foo
+        @param {string} [bar] - optional bar
+
+        @example
+        {% render 'loading-spinner', foo: 'foo' %}
+        {% render 'loading-spinner', foo: 'foo', bar: 'bar' %}
+      {% enddoc %}
+    LIQUID
+
+    assert_template_result('', template)
+  end
+
+  def test_doc_tag_body_content
+    doc_content = "  Documentation content\n  @param {string} foo - test\n"
+    template_source = "{% doc %}#{doc_content}{% enddoc %}"
+
+    doc_tag = nil
+    ParseTreeVisitor
+      .for(Template.parse(template_source).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        doc_tag = tag
+      end
+      .visit
+
+    assert_equal(doc_content, doc_tag.nodelist.first.to_s)
+  end
+
+  def test_doc_tag_does_not_support_extra_arguments
+    error = assert_raises(Liquid::SyntaxError) do
+      template = <<~LIQUID.chomp
+        {% doc extra %}
+        {% enddoc %}
+      LIQUID
+
+      Liquid::Template.parse(template)
+    end
+
+    exp_error = "Liquid syntax error: Syntax Error in 'doc' - Valid syntax: {% doc %}{% enddoc %}"
+    act_error = error.message
+
+    assert_equal(exp_error, act_error)
+  end
+
+  def test_doc_tag_must_support_valid_tags
+    assert_match_syntax_error("Liquid syntax error (line 1): 'doc' tag was never closed", '{% doc %} foo')
+    assert_match_syntax_error("Liquid syntax error (line 1): Syntax Error in 'doc' - Valid syntax: {% doc %}{% enddoc %}", '{% doc } foo {% enddoc %}')
+    assert_match_syntax_error("Liquid syntax error (line 1): Syntax Error in 'doc' - Valid syntax: {% doc %}{% enddoc %}", '{% doc } foo %}{% enddoc %}')
+  end
+
+  def test_doc_tag_ignores_liquid_nodes
+    template = <<~LIQUID.chomp
+      {% doc %}
+        {% if true %}
+        {% if ... %}
+        {%- for ? -%}
+        {% while true %}
+        {%
+          unless if
+        %}
+        {% endcase %}
+      {% enddoc %}
+    LIQUID
+
+    assert_template_result('', template)
+  end
+
+  def test_doc_tag_ignores_unclosed_liquid_tags
+    template = <<~LIQUID.chomp
+      {% doc %}
+        {% if true %}
+      {% enddoc %}
+    LIQUID
+
+    assert_template_result('', template)
+  end
+
+  def test_doc_tag_does_not_allow_nested_docs
+    error = assert_raises(Liquid::SyntaxError) do
+      template = <<~LIQUID.chomp
+        {% doc %}
+          {% doc %}
+            {% doc %}
+        {% enddoc %}
+      LIQUID
+
+      Liquid::Template.parse(template)
+    end
+
+    exp_error = "Liquid syntax error: Syntax Error in 'doc' - Nested doc tags are not allowed"
+    act_error = error.message
+
+    assert_equal(exp_error, act_error)
+  end
+
+  def test_doc_tag_ignores_nested_raw_tags
+    template = <<~LIQUID.chomp
+      {% doc %}
+        {% raw %}
+      {% enddoc %}
+    LIQUID
+
+    assert_template_result('', template)
+  end
+
+  def test_doc_tag_ignores_unclosed_assign
+    template = <<~LIQUID.chomp
+      {% doc %}
+        {% assign foo = "1"
+      {% enddoc %}
+    LIQUID
+
+    assert_template_result('', template)
+  end
+
+  def test_doc_tag_ignores_malformed_syntax
+    template = <<~LIQUID.chomp
+      {% doc %}
+      {% {{ {%- enddoc %}
+    LIQUID
+
+    assert_template_result('', template)
+  end
+
+  def test_doc_tag_captures_token_before_enddoc
+    template_source = "{% doc %}{{ incomplete{% enddoc %}"
+
+    doc_tag = nil
+    ParseTreeVisitor
+      .for(Template.parse(template_source).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        doc_tag = tag
+      end
+      .visit
+
+    assert_equal("{{ incomplete", doc_tag.nodelist.first.to_s)
+  end
+
+  def test_doc_tag_preserves_error_line_numbers
+    template = Liquid::Template.parse(<<~LIQUID.chomp, line_numbers: true)
+      {% doc %}
+        {% if true %}
+      {% enddoc %}
+      {{ errors.standard_error }}
+    LIQUID
+
+    expected = <<~TEXT.chomp
+
+      Liquid error (line 4): standard error
+    TEXT
+
+    assert_equal(expected, template.render('errors' => ErrorDrop.new))
+  end
+
+  def test_doc_tag_whitespace_control
+    # Basic whitespace control
+    assert_template_result("Hello!", "      {%- doc -%}123{%- enddoc -%}Hello!")
+    assert_template_result("Hello!", "{%- doc -%}123{%- enddoc -%}     Hello!")
+    assert_template_result("Hello!", "      {%- doc -%}123{%- enddoc -%}     Hello!")
+    assert_template_result("Hello!", <<~LIQUID.chomp)
+      {%- doc %}Whitespace control!{% enddoc -%}
+      Hello!
+    LIQUID
+  end
+
+  def test_doc_tag_delimiter_handling
+    assert_template_result('', <<~LIQUID.chomp)
+      {%- if true -%}
+        {%- doc -%}
+          {%- docEXTRA -%}wut{% enddocEXTRA -%}xyz
+        {%- enddoc -%}
+      {%- endif -%}
+    LIQUID
+
+    assert_template_result('', "{% doc %}123{% enddoc xyz %}")
+    assert_template_result('', "{% doc %}123{% enddoc\txyz %}")
+    assert_template_result('', "{% doc %}123{% enddoc\nxyz %}")
+    assert_template_result('', "{% doc %}123{% enddoc\n   xyz  enddoc %}")
+  end
+
+  def test_doc_tag_visitor
+    template_source = '{% doc %}{% enddoc %}'
+
+    assert_equal(
+      [Liquid::Doc],
+      visit(template_source),
+    )
+  end
+
+  def test_doc_tag_blank_with_empty_content
+    template_source = "{% doc %}{% enddoc %}"
+
+    doc_tag = nil
+    ParseTreeVisitor
+      .for(Template.parse(template_source).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        doc_tag = tag
+      end
+      .visit
+
+    assert_equal(true, doc_tag.blank?)
+  end
+
+  def test_doc_tag_blank_with_content
+    template_source = "{% doc %}Some documentation{% enddoc %}"
+
+    doc_tag = nil
+    ParseTreeVisitor
+      .for(Template.parse(template_source).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        doc_tag = tag
+      end
+      .visit
+
+    assert_equal(false, doc_tag.blank?)
+  end
+
+  def test_doc_tag_blank_with_whitespace_only
+    template_source = "{% doc %}    {% enddoc %}"
+
+    doc_tag = nil
+    ParseTreeVisitor
+      .for(Template.parse(template_source).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        doc_tag = tag
+      end
+      .visit
+
+    assert_equal(false, doc_tag.blank?)
+  end
+
+  def test_doc_tag_nodelist_returns_array_with_body
+    doc_content = "Documentation content\n@param {string} foo"
+    template_source = "{% doc %}#{doc_content}{% enddoc %}"
+
+    doc_tag = nil
+    ParseTreeVisitor
+      .for(Template.parse(template_source).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        doc_tag = tag
+      end
+      .visit
+
+    assert_equal([doc_content], doc_tag.nodelist)
+    assert_equal(1, doc_tag.nodelist.length)
+    assert_equal(doc_content, doc_tag.nodelist.first)
+  end
+
+  def test_doc_tag_nodelist_with_empty_content
+    template_source = "{% doc %}{% enddoc %}"
+
+    doc_tag = nil
+    ParseTreeVisitor
+      .for(Template.parse(template_source).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        doc_tag = tag
+      end
+      .visit
+
+    assert_equal([""], doc_tag.nodelist)
+    assert_equal(1, doc_tag.nodelist.length)
+  end
+
+  private
+
+  def traversal(template)
+    ParseTreeVisitor
+      .for(Template.parse(template).root)
+      .add_callback_for(Liquid::Doc) do |tag|
+        tag_class = tag.class
+        tag_class
+      end
+  end
+
+  def visit(template)
+    traversal(template).visit.flatten.compact
+  end
+end

test/unit/template_unit_test.rb

@@ -35,4 +35,15 @@ class TemplateUnitTest < Minitest::Test
   def test_template_inheritance
     assert_equal("foo", TemplateSubclass.parse("foo").render)
   end
+
+  def test_invalid_utf8
+    input = "\xff\x00"
+    error = assert_raises(SyntaxError) do
+      Liquid::Tokenizer.new(source: input, string_scanner: StringScanner.new(input))
+    end
+    assert_equal(
+      'Liquid syntax error: Invalid byte sequence in UTF-8',
+      error.message,
+    )
+  end
 end

test/unit/variable_unit_test.rb

@@ -108,7 +108,7 @@ class VariableUnitTest < Minitest::Test
     assert_equal(VariableLookup.new('foo-bar'), create_variable('foo-bar').name)
     assert_equal(VariableLookup.new('foo-bar-2'), create_variable('foo-bar-2').name)
 
-    with_error_mode(:strict) do
+    with_error_modes(:strict) do
       assert_raises(Liquid::SyntaxError) { create_variable('foo - bar') }
       assert_raises(Liquid::SyntaxError) { create_variable('-foo') }
       assert_raises(Liquid::SyntaxError) { create_variable('2foo') }
@@ -135,16 +135,68 @@ class VariableUnitTest < Minitest::Test
     var = create_variable(%( number_of_comments | pluralize: 'comment': 'comments' ), error_mode: :lax)
     assert_equal(VariableLookup.new('number_of_comments'), var.name)
     assert_equal([['pluralize', ['comment', 'comments']]], var.filters)
+
+    # missing does not throws error
+    create_variable(%(n | f1: ,), error_mode: :lax)
+    create_variable(%(n | f1: ,| f2), error_mode: :lax)
+
+    # arg does not require colon, but ignores args :O, also ignores first kwarg since it splits on ':'
+    var = create_variable(%(n | f1 1 | f2 k1: v1), error_mode: :lax)
+    assert_equal([['f1', []], ['f2', [VariableLookup.new('v1')]]], var.filters)
+
+    # positional and kwargs parsing
+    var = create_variable(%(n | filter: 1, 2, 3 | filter2: k1: 1, k2: 2), error_mode: :lax)
+    assert_equal([['filter', [1, 2, 3]], ['filter2', [], { "k1" => 1, "k2" => 2 }]], var.filters)
+
+    # positional and kwargs intermixed (pos1, key1: val1, pos2)
+    var = create_variable(%(n | link_to: class: "black", "https://example.com", title: "title"), error_mode: :lax)
+    assert_equal([['link_to', ["https://example.com"], { "class" => "black", "title" => "title" }]], var.filters)
   end
 
   def test_strict_filter_argument_parsing
-    with_error_mode(:strict) do
+    with_error_modes(:strict) do
       assert_raises(SyntaxError) do
         create_variable(%( number_of_comments | pluralize: 'comment': 'comments' ))
       end
     end
   end
 
+  def test_rigid_filter_argument_parsing
+    with_error_modes(:rigid) do
+      # optional colon
+      var = create_variable(%(n | f1 | f2:))
+      assert_equal([['f1', []], ['f2', []]], var.filters)
+
+      # missing argument throws error
+      assert_raises(SyntaxError) { create_variable(%(n | f1: ,)) }
+      assert_raises(SyntaxError) { create_variable(%(n | f1: ,| f2)) }
+
+      # arg requires colon
+      assert_raises(SyntaxError) { create_variable(%(n | f1 1)) }
+
+      # trailing comma doesn't throw
+      create_variable(%(n | f1: 1, 2, 3, | f2:))
+
+      # missing comma throws error
+      assert_raises(SyntaxError) { create_variable(%(n | filter: 1 2, 3)) }
+
+      # positional and kwargs parsing
+      var = create_variable(%(n | filter: 1, 2, 3 | filter2: k1: 1, k2: 2))
+      assert_equal([['filter', [1, 2, 3]], ['filter2', [], { "k1" => 1, "k2" => 2 }]], var.filters)
+
+      # positional and kwargs mixed
+      var = create_variable(%(n | filter: 'a', 'b', key1: 1, key2: 2, 'c'))
+      assert_equal([["filter", ["a", "b", "c"], { "key1" => 1, "key2" => 2 }]], var.filters)
+
+      # positional and kwargs intermixed (pos1, key1: val1, pos2)
+      var = create_variable(%(n | link_to: class: "black", "https://example.com", title: "title"))
+      assert_equal([['link_to', ["https://example.com"], { "class" => "black", "title" => "title" }]], var.filters)
+
+      # string key throws
+      assert_raises(SyntaxError) { create_variable(%(n | pluralize: 'comment': 'comments')) }
+    end
+  end
+
   def test_output_raw_source_of_variable
     var = create_variable(%( name_of_variable | upcase ))
     assert_equal(" name_of_variable | upcase ", var.raw)