Create a BlockBody class to decouple block body parsing from tags.

lib/liquid/document.rb

@@ -1,17 +1,18 @@
 module Liquid
-  class Document < Block
-    def self.parse(tokens, options={})
-      # we don't need markup to open this block
-      super(nil, nil, tokens, options)
+  class Document < BlockBody
+    def parse(tokens)
+      super do |end_tag_name, end_tag_params|
+        unknown_tag(end_tag_name) if end_tag_name
+      end
     end
 
-    # There isn't a real delimiter
-    def block_delimiter
-      []
-    end
-
-    # Document blocks don't need to be terminated since they are not actually opened
-    def assert_missing_delimitation!
+    def unknown_tag(tag)
+      case tag
+      when 'else'.freeze, 'end'.freeze
+        raise SyntaxError.new(@options[:locale].t("errors.syntax.unexpected_outer_tag".freeze, :tag => tag))
+      else
+        raise SyntaxError.new(@options[:locale].t("errors.syntax.unknown_tag".freeze, :tag => tag))
+      end
     end
   end
 end