codekingpro/portable-devtools

1# Protocol Buffers - Google's data interchange format2# Copyright 2008 Google Inc.  All rights reserved.3#4# Use of this source code is governed by a BSD-style5# license that can be found in the LICENSE file or at6# https://developers.google.com/open-source/licenses/bsd7 8# This code is meant to work on Python 2.4 and above only.9 10"""Contains a metaclass and helper functions used to create11protocol message classes from Descriptor objects at runtime.12 13Recall that a metaclass is the "type" of a class.14(A class is to a metaclass what an instance is to a class.)15 16In this case, we use the GeneratedProtocolMessageType metaclass17to inject all the useful functionality into the classes18output by the protocol compiler at compile-time.19 20The upshot of all this is that the real implementation21details for ALL pure-Python protocol buffers are *here in22this file*.23"""24 25__author__ = 'robinson@google.com (Will Robinson)'26 27 28from google.protobuf import message_factory29from google.protobuf import symbol_database30 31# The type of all Message classes.32# Part of the public interface, but normally only used by message factories.33GeneratedProtocolMessageType = message_factory._GENERATED_PROTOCOL_MESSAGE_TYPE34 35MESSAGE_CLASS_CACHE = {}36 37 38# Deprecated. Please NEVER use reflection.ParseMessage().39def ParseMessage(descriptor, byte_str):40  """Generate a new Message instance from this Descriptor and a byte string.41 42  DEPRECATED: ParseMessage is deprecated because it is using MakeClass().43  Please use MessageFactory.GetPrototype() instead.44 45  Args:46    descriptor: Protobuf Descriptor object47    byte_str: Serialized protocol buffer byte string48 49  Returns:50    Newly created protobuf Message object.51  """52  result_class = MakeClass(descriptor)53  new_msg = result_class()54  new_msg.ParseFromString(byte_str)55  return new_msg56 57 58# Deprecated. Please NEVER use reflection.MakeClass().59def MakeClass(descriptor):60  """Construct a class object for a protobuf described by descriptor.61 62  DEPRECATED: use MessageFactory.GetPrototype() instead.63 64  Args:65    descriptor: A descriptor.Descriptor object describing the protobuf.66  Returns:67    The Message class object described by the descriptor.68  """69  # Original implementation leads to duplicate message classes, which won't play70  # well with extensions. Message factory info is also missing.71  # Redirect to message_factory.72  return message_factory.GetMessageClass(descriptor)73