Mojom: Add 'default' keyword for initializing structs to non-null value.

mojo/public/tools/bindings/generators/mojom_js_generator.py

 # Copyright 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 """Generates JavaScript source files from a mojom.Module."""
 
 import mojom.generate.generator as generator
 import mojom.generate.module as mojom
 import mojom.generate.pack as pack
 from mojom.generate.template_expander import UseJinja
@@ skipping 14 matching lines @@
   mojom.SHAREDBUFFER: "null",
   mojom.INT64:        "0",
   mojom.UINT64:       "0",
   mojom.DOUBLE:       "0",
   mojom.STRING:       '""',
 }
 
 
 def JavaScriptDefaultValue(field):
   if field.default:
-    raise Exception("Default values should've been handled in jinja.")
+    if isinstance(field.kind, mojom.Struct):
+      assert field.default == "default"
+      return "new %s()" % JavascriptType(field.kind)
+    return ExpressionToText(field.default)
   if field.kind in mojom.PRIMITIVES:
     return _kind_to_javascript_default_value[field.kind]
   if isinstance(field.kind, mojom.Struct):
     return "null"
   if isinstance(field.kind, mojom.Array):
     return "[]"
   if isinstance(field.kind, mojom.Interface) or \
      isinstance(field.kind, mojom.InterfaceRequest):
     return _kind_to_javascript_default_value[mojom.MSGPIPE]
   if isinstance(field.kind, mojom.Enum):
@@ skipping 101 matching lines @@
 
 
 class Generator(generator.Generator):
 
   js_filters = {
     "default_value": JavaScriptDefaultValue,
     "payload_size": JavaScriptPayloadSize,
     "decode_snippet": JavaScriptDecodeSnippet,
     "encode_snippet": JavaScriptEncodeSnippet,
     "expression_to_text": ExpressionToText,
-    "is_object_kind": generator.IsObjectKind,
-    "is_string_kind": generator.IsStringKind,
-    "is_array_kind": lambda kind: isinstance(kind, mojom.Array),
     "js_type": JavascriptType,
     "stylize_method": generator.StudlyCapsToCamel,
-    "verify_token_type": generator.VerifyTokenType,
   }
 
   @UseJinja("js_templates/module.js.tmpl", filters=js_filters)
   def GenerateJsModule(self):
     return {
       "imports": self.GetImports(),
       "kinds": self.module.kinds,
       "enums": self.module.enums,
       "module": self.module,
       "structs": self.GetStructs() + self.GetStructsFromMethods(),
       "interfaces": self.module.interfaces,
     }
 
   def GenerateFiles(self, args):
     self.Write(self.GenerateJsModule(), "%s.js" % self.module.name)
 
   def GetImports(self):
     # Since each import is assigned a variable in JS, they need to have unique
     # names.
     counter = 1
     for each in self.module.imports:
       each["unique_name"] = "import" + str(counter)
       counter += 1
     return self.module.imports