Mojo: Mojom: Add AST type for struct fields.

mojo/public/tools/bindings/pylib/mojom/parse/parser.py

 # Copyright 2014 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 imp
 import os.path
 import sys
 
@@ skipping 163 matching lines @@
   def p_struct_body(self, p):
     """struct_body : field struct_body
                    | enum struct_body
                    | const struct_body
                    | """
     if len(p) > 1:
       p[0] = _ListFromConcat(p[1], p[2])
 
   def p_field(self, p):
     """field : typename NAME ordinal default SEMI"""
-    p[0] = ('FIELD', p[1], p[2], p[3], p[4])
+    p[0] = ast.StructField(p[2], p[3], p[1], p[4])
 
-  def p_default(self, p):
-    """default : EQUALS constant
-               | """
-    if len(p) > 2:
-      p[0] = p[2]
+  def p_default_1(self, p):
+    """default : """
+    p[0] = None
+
+  def p_default_2(self, p):
+    """default : EQUALS constant"""
+    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
                       | const interface_body
@@ skipping 23 matching lines @@
     """nonempty_parameter_list : parameter"""
     p[0] = ast.ParameterList(p[1])
 
   def p_nonempty_parameter_list_2(self, p):
     """nonempty_parameter_list : nonempty_parameter_list COMMA parameter"""
     p[0] = p[1]
     p[0].Append(p[3])
 
   def p_parameter(self, p):
     """parameter : typename NAME ordinal"""
-    p[0] = ast.Parameter(p[1], p[2], p[3],
+    p[0] = ast.Parameter(p[2], p[3], p[1],
                          filename=self.filename, lineno=p.lineno(2))
 
   def p_typename(self, p):
     """typename : basictypename
                 | array
                 | fixed_array
                 | interfacerequest"""
     p[0] = p[1]
 
   def p_basictypename(self, p):
@@ skipping 130 matching lines @@
 
 def Parse(source, filename):
   lexer = Lexer(filename)
   parser = Parser(lexer, source, filename)
 
   lex.lex(object=lexer)
   yacc.yacc(module=parser, debug=0, write_tables=0)
 
   tree = yacc.parse(source)
   return tree