Some more refactorings of overload dispatcher generation.

tools/dom/scripts/htmldartgenerator.py

 #!/usr/bin/python
 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 """This module provides shared functionality for the system to generate
 dart:html APIs from the IDL database."""
 
 from generator import AnalyzeOperation, ConstantOutputOrder, \
     DartDomNameOfAttribute, FindMatchingAttribute, IsDartCollectionType, \
@@ skipping 158 matching lines @@
         self.EmitOperation(info, '_item')
       return
 
     if declare_only:
       self.DeclareOperation(info,
           self.SecureOutputType(info.type_name), method_name)
     else:
       self.EmitOperation(info, method_name)
 
   def _GenerateDispatcherBody(self,
-      emitter,
       operations,
       parameter_names,
+      declaration,
       generate_call,
       is_optional,
       can_omit_type_check=lambda type, pos: False):
 
+    body_emitter = self._members_emitter.Emit(
+        '\n'
+        '  $DECLARATION {\n'
+        '$!BODY'
+        '  }\n',
+        DECLARATION=declaration)
+
+    version = [0]
+    def GenerateCall(operation, argument_count, checks):
+      if checks:
+        (stmts_emitter, call_emitter) = body_emitter.Emit(
+            '    if ($CHECKS) {\n$!STMTS$!CALL    }\n',
+            INDENT='      ',
+            CHECKS=' && '.join(checks))
+      else:
+        (stmts_emitter, call_emitter) = body_emitter.Emit(
+            '$!STMTS$!CALL',
+            INDENT='    ');
+
+      if operation.type.id == 'void':
+        call_emitter = call_emitter.Emit('$(INDENT)$!CALL;\n$(INDENT)return;\n')
+      else:
+        call_emitter = call_emitter.Emit('$(INDENT)return $!CALL;\n')
+
+      version[0] += 1
+      generate_call(
+          stmts_emitter, call_emitter, version[0], operation, argument_count)
+
     def GenerateChecksAndCall(operation, argument_count):
       checks = []
       for i in range(0, argument_count):
         argument = operation.arguments[i]
         parameter_name = parameter_names[i]
         test_type = self._DartType(argument.type.id)
         if test_type in ['dynamic', 'Object']:
           checks.append('?%s' % parameter_name)
         elif not can_omit_type_check(test_type, i):
           checks.append('(%s is %s || %s == null)' % (
               parameter_name, test_type, parameter_name))
       # There can be multiple presence checks.  We need them all since a later
       # optional argument could have been passed by name, leaving 'holes'.
       checks.extend(['!?%s' % name for name in parameter_names[argument_count:]])
 
-      generate_call(operation, argument_count, checks)
+      GenerateCall(operation, argument_count, checks)
 
     # TODO: Optimize the dispatch to avoid repeated checks.
     if len(operations) > 1:
       for operation in operations:
         for position, argument in enumerate(operation.arguments):
           if is_optional(operation, argument):
             GenerateChecksAndCall(operation, position)
         GenerateChecksAndCall(operation, len(operation.arguments))
-      emitter.Emit(
+      body_emitter.Emit(
           '    throw new ArgumentError("Incorrect number or type of arguments");'
           '\n');
     else:
       operation = operations[0]
       argument_count = len(operation.arguments)
       for position, argument in list(enumerate(operation.arguments))[::-1]:
         if is_optional(operation, argument):
           check = '?%s' % parameter_names[position]
           # argument_count instead of position + 1 is used here to cover one
           # complicated case with the effectively optional argument in the middle.
           # Consider foo(x, [Optional] y, [Optional=DefaultIsNullString] z)
           # (as of now it's modelled after HTMLMediaElement.webkitAddKey).
           # y is optional in WebCore, while z is not.
           # In this case, if y was actually passed, we'd like to emit foo(x, y, z) invocation,
           # not foo(x, y).
-          generate_call(operation, argument_count, [check])
+          GenerateCall(operation, argument_count, [check])
           argument_count = position
-      generate_call(operation, argument_count, [])
+      GenerateCall(operation, argument_count, [])
 
   def AdditionalImplementedInterfaces(self):
     # TODO: Include all implemented interfaces, including other Lists.
     implements = []
     if self._interface_type_info.is_typed_array():
       element_type = self._interface_type_info.list_item_type()
       implements.append('List<%s>' % self._DartType(element_type))
     if self._interface_type_info.list_item_type():
       item_type_info = self._type_registry.TypeInfo(
           self._interface_type_info.list_item_type())
@@ skipping 205 matching lines @@
         walk(interface.parents)
       else:
         walk(interface.parents[1:])
     return result
 
   def _DartType(self, type_name):
     return self._type_registry.DartType(type_name)
 
   def _IsPrivate(self, name):
     return name.startswith('_')