Update {% doc %} to no longer support nested tags (as {% comment %} does)

lib/liquid/locales/en.yml

@@ -8,6 +8,7 @@
       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"

lib/liquid/tags/comment.rb

@@ -15,8 +15,6 @@ module Liquid
   #   {% endcomment %}
   # @liquid_syntax_keyword content The content of the comment.
   class Comment < Block
-    TAG_NAME = "comment"
-
     def render_to_output_buffer(_context, output)
       output
     end
@@ -36,10 +34,7 @@ module Liquid
       end
 
       parse_context.depth += 1
-      tag_depth = 1
-
-      begin_tag = self.class::TAG_NAME
-      end_tag = "end#{self.class::TAG_NAME}"
+      comment_tag_depth = 1
 
       begin
         # Consume tokens without creating child nodes.
@@ -62,13 +57,13 @@ module Liquid
           case tag_name
           when "raw"
             parse_raw_tag_body(tokenizer)
-          when begin_tag
-            tag_depth += 1
-          when end_tag
-            tag_depth -= 1
+          when "comment"
+            comment_tag_depth += 1
+          when "endcomment"
+            comment_tag_depth -= 1
           end
 
-          if tag_depth.zero?
+          if comment_tag_depth.zero?
             parse_context.trim_whitespace = (token[-3] == WhitespaceControl) unless tokenizer.for_liquid_tag
             return false
           end

lib/liquid/tags/doc.rb

@@ -24,7 +24,48 @@ module Liquid
   #     {% render 'message', foo: 'Hello', bar: 'World' %}
   #   {% enddoc %}
   #   {{ foo }}, {{ bar }}!
-  class Doc < Comment
-    TAG_NAME = "doc"
+  class Doc < Block
+    def render_to_output_buffer(_context, output)
+      output
+    end
+
+    def unknown_tag(_tag, _markup, _tokens)
+    end
+
+    def blank?
+      true
+    end
+
+    def parse_body(body, tokenizer)
+      while (token = tokenizer.send(:shift))
+        tag_name = if tokenizer.for_liquid_tag
+          next if token.empty? || token.match?(BlockBody::WhitespaceOrNothing)
+
+          tag_name_match = BlockBody::LiquidTagToken.match(token)
+
+          next if tag_name_match.nil?
+
+          tag_name_match[1]
+        else
+          token =~ BlockBody::FullToken
+          Regexp.last_match(2)
+        end
+
+        raise_nested_doc_error if tag_name == "doc"
+
+        if tag_name == "enddoc"
+          parse_context.trim_whitespace = (token[-3] == WhitespaceControl) unless tokenizer.for_liquid_tag
+          return false
+        end
+      end
+
+      raise_tag_never_closed(block_name)
+    end
+
+    private
+
+    def raise_nested_doc_error
+      raise SyntaxError, parse_context.locale.t("errors.syntax.doc_invalid_nested")
+    end
   end
 end