Adds parent template tracking to snippet drops

Enhances snippet drops to track their parent template name, enabling better error reporting and context awareness within rendered snippets.

Updates the render tag to use parent template names for proper context variable naming and improves error handling flow.

lib/liquid.rb

@@ -67,6 +67,7 @@ require 'liquid/i18n'
 require 'liquid/drop'
 require 'liquid/tablerowloop_drop'
 require 'liquid/forloop_drop'
+require 'liquid/snippet_drop'
 require 'liquid/extensions'
 require 'liquid/errors'
 require 'liquid/interrupts'

lib/liquid/locales/en.yml

@@ -5,6 +5,7 @@
       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]"
+      snippet: "Syntax Error in 'snippet' - Valid syntax: snippet [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) "
@@ -19,6 +20,7 @@
       invalid_delimiter: "'%{tag}' is not a valid delimiter for %{block_name} tags. use %{block_delimiter}"
       invalid_template_encoding: "Invalid template encoding"
       render: "Syntax error in tag 'render' - Template name must be a quoted string"
+      render_invalid_template_name: "Syntax error in tag 'render' - Expected a string or identifier, found %{found}"
       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"
@@ -29,5 +31,6 @@
       variable_termination: "Variable '%{token}' was not properly terminated with regexp: %{tag_end}"
     argument:
       include: "Argument error in tag 'include' - Illegal template name"
+      render: "Argument error in tag 'render' - Dynamically chosen templates are not allowed"
     disabled:
       tag: "usage is not allowed in this context"

lib/liquid/snippet_drop.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module Liquid
+  class SnippetDrop < Drop
+    attr_reader :body, :name, :parent_name
+
+    def initialize(body, name, parent_name)
+      super()
+      @body = body
+      @name = name
+      @parent_name = parent_name
+    end
+
+    def to_partial
+      @body
+    end
+
+    def to_s
+      'SnippetDrop'
+    end
+  end
+end

lib/liquid/tags.rb

@@ -20,6 +20,7 @@ require_relative "tags/raw"
 require_relative "tags/render"
 require_relative "tags/cycle"
 require_relative "tags/doc"
+require_relative "tags/snippet"
 
 module Liquid
   module Tags
@@ -44,6 +45,7 @@ module Liquid
       'echo' => Echo,
       'tablerow' => TableRow,
       'doc' => Doc,
+      'snippet' => Snippet,
     }.freeze
   end
 end

lib/liquid/tags/render.rb

@@ -27,7 +27,7 @@ module Liquid
   # @liquid_syntax_keyword filename The name of the snippet to render, without the `.liquid` extension.
   class Render < Tag
     FOR = 'for'
-    SYNTAX = /(#{QuotedString}+)(\s+(with|#{FOR})\s+(#{QuotedFragment}+))?(\s+(?:as)\s+(#{VariableSegment}+))?/o
+    SYNTAX = /(#{QuotedString}+|#{VariableSegment}+)(\s+(with|#{FOR})\s+(#{QuotedFragment}+))?(\s+(?:as)\s+(#{VariableSegment}+))?/o
 
     disable_tags "include"
 
@@ -47,21 +47,25 @@ module Liquid
     end
 
     def render_tag(context, output)
-      # The expression should be a String literal, which parses to a String object
-      template_name = @template_name_expr
-      raise ::ArgumentError unless template_name.is_a?(String)
+      template = context.evaluate(@template_name_expr)
 
-      partial = PartialCache.load(
-        template_name,
-        context: context,
-        parse_context: parse_context,
-      )
+      if template.respond_to?(:to_partial)
+        partial = template.to_partial
+        template_name = template.parent_name
+        context_variable_name = @alias_name || template.name.split('/').last
 
-      context_variable_name = @alias_name || template_name.split('/').last
+      elsif @template_name_expr.is_a?(String)
+        partial = PartialCache.load(template, context: context, parse_context: parse_context)
+        template_name = partial.name
+        context_variable_name = @alias_name || template_name.split('/').last
+
+      else
+        raise ::ArgumentError, parse_context.locale.t("errors.argument.render")
+      end
 
       render_partial_func = ->(var, forloop) {
         inner_context               = context.new_isolated_subcontext
-        inner_context.template_name = partial.name
+        inner_context.template_name = template_name
         inner_context.partial       = true
         inner_context['forloop']    = forloop if forloop
 
@@ -101,14 +105,18 @@ module Liquid
         key = p.consume
         p.consume(:colon)
         @attributes[key] = safe_parse_expression(p)
-        p.consume?(:comma)
+        p.consume?(:comma) # optional comma
       end
 
       p.consume(:end_of_string)
     end
 
     def rigid_template_name(p)
-      p.consume(:string)
+      return p.consume(:string) if p.look(:string)
+      return p.consume(:id) if p.look(:id)
+
+      found = p.consume || "nothing"
+      raise SyntaxError, options[:locale].t("errors.syntax.render_invalid_template_name", found: found)
     end
 
     def strict_parse(markup)

lib/liquid/tags/snippet.rb

@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+module Liquid
+  # @liquid_public_docs
+  # @liquid_type tag
+  # @liquid_category variable
+  # @liquid_name snippet
+  # @liquid_summary
+  #   Creates a new inline snippet.
+  # @liquid_description
+  #   You can create inline snippets to make your Liquid code more modular.
+  # @liquid_syntax
+  #   {% snippet snippet_name %}
+  #     value
+  #   {% endsnippet %}
+  class Snippet < Block
+    def initialize(tag_name, markup, options)
+      super
+      p = @parse_context.new_parser(markup)
+      if p.look(:id)
+        @to = p.consume(:id)
+        p.consume(:end_of_string)
+      else
+        raise SyntaxError, options[:locale].t("errors.syntax.snippet")
+      end
+    end
+
+    def render_to_output_buffer(context, output)
+      snippet_drop = SnippetDrop.new(@body, @to, context.template_name)
+      context.scopes.last[@to] = snippet_drop
+      context.resource_limits.increment_assign_score(assign_score_of(snippet_drop))
+      output
+    end
+
+    def blank?
+      true
+    end
+
+    private
+
+    def assign_score_of(snippet_drop)
+      snippet_drop.body.nodelist.sum { |node| node.to_s.bytesize }
+    end
+  end
+end

test/integration/tags/render_tag_test.rb

@@ -101,8 +101,11 @@ class RenderTagTest < Minitest::Test
     end
   end
 
-  def test_dynamically_choosen_templates_are_not_allowed
-    assert_syntax_error("{% assign name = 'snippet' %}{% render name %}")
+  def test_dynamically_chosen_templates_are_not_allowed
+    error = assert_raises(::ArgumentError) do
+      Template.parse('{% assign name = "snippet" %}{% render name %}').render!
+    end
+    assert_equal("Argument error in tag 'render' - Dynamically chosen templates are not allowed", error.message)
   end
 
   def test_rigid_parsing_errors
@@ -294,6 +297,13 @@ class RenderTagTest < Minitest::Test
     )
   end
 
+  def test_render_tag_with_snippet_drop
+    assert_template_result(
+      "Hello from snippet",
+      "{% snippet my_snippet %}Hello from snippet{% endsnippet %}{% render my_snippet %}",
+    )
+  end
+
   def test_render_tag_renders_error_with_template_name
     assert_template_result(
       'Liquid error (foo line 1): standard error',