Support default values for POD struct fields in mojom IDL.

mojo/public/bindings/parse/mojo_parser.py

 #!/usr/bin/env python
 # 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 a syntax tree from a Mojo IDL file."""
 
 
 import sys
 import os.path
@@ skipping 77 matching lines @@
     p[0] = ('STRUCT', p[3], p[1], p[5])
 
   def p_struct_body(self, p):
     """struct_body : field struct_body
                    | enum struct_body
                    |"""
     if len(p) > 1:
       p[0] = ListFromConcat(p[1], p[2])
 
   def p_field(self, p):
-    """field : typename NAME ordinal SEMI"""
-    p[0] = ('FIELD', p[1], p[2], p[3])
+    """field : typename NAME default ordinal SEMI"""
+    p[0] = ('FIELD', p[1], p[2], p[4], p[3])
+
+  def p_default(self, p):
+    """default : EQUALS expression
+               | """
+    if len(p) > 2:
+      p[0] = p[2]
 
   def p_interface(self, p):
     """interface : attribute_section INTERFACE NAME LBRACE interface_body RBRACE SEMI"""
     p[0] = ('INTERFACE', p[3], p[1], p[5])
 
   def p_interface_body(self, p):
     """interface_body : method interface_body
                       | enum interface_body
                       | """
     if len(p) > 1:
@@ skipping 160 matching lines @@
 def Main():
   if len(sys.argv) < 2:
     print("usage: %s filename" % (sys.argv[0]))
     sys.exit(1)
   tree = Parse(filename=sys.argv[1])
   print(tree)
 
 
 if __name__ == '__main__':
   Main()