1# Protocol Buffers - Google's data interchange format 2# Copyright 2008 Google Inc. All rights reserved. 3# https://developers.google.com/protocol-buffers/ 4# 5# Redistribution and use in source and binary forms, with or without 6# modification, are permitted provided that the following conditions are 7# met: 8# 9# * Redistributions of source code must retain the above copyright 10# notice, this list of conditions and the following disclaimer. 11# * Redistributions in binary form must reproduce the above 12# copyright notice, this list of conditions and the following disclaimer 13# in the documentation and/or other materials provided with the 14# distribution. 15# * Neither the name of Google Inc. nor the names of its 16# contributors may be used to endorse or promote products derived from 17# this software without specific prior written permission. 18# 19# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 20# "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 21# LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR 22# A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 23# OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 24# SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT 25# LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, 26# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY 27# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 28# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE 29# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 31# This code is meant to work on Python 2.4 and above only. 32 33"""Contains a metaclass and helper functions used to create 34protocol message classes from Descriptor objects at runtime. 35 36Recall that a metaclass is the "type" of a class. 37(A class is to a metaclass what an instance is to a class.) 38 39In this case, we use the GeneratedProtocolMessageType metaclass 40to inject all the useful functionality into the classes 41output by the protocol compiler at compile-time. 42 43The upshot of all this is that the real implementation 44details for ALL pure-Python protocol buffers are *here in 45this file*. 46""" 47 48__author__ = 'robinson@google.com (Will Robinson)' 49 50 51from google.protobuf import message_factory 52from google.protobuf import symbol_database 53 54# The type of all Message classes. 55# Part of the public interface, but normally only used by message factories. 56GeneratedProtocolMessageType = message_factory._GENERATED_PROTOCOL_MESSAGE_TYPE 57 58MESSAGE_CLASS_CACHE = {} 59 60 61# Deprecated. Please NEVER use reflection.ParseMessage(). 62def ParseMessage(descriptor, byte_str): 63 """Generate a new Message instance from this Descriptor and a byte string. 64 65 DEPRECATED: ParseMessage is deprecated because it is using MakeClass(). 66 Please use MessageFactory.GetPrototype() instead. 67 68 Args: 69 descriptor: Protobuf Descriptor object 70 byte_str: Serialized protocol buffer byte string 71 72 Returns: 73 Newly created protobuf Message object. 74 """ 75 result_class = MakeClass(descriptor) 76 new_msg = result_class() 77 new_msg.ParseFromString(byte_str) 78 return new_msg 79 80 81# Deprecated. Please NEVER use reflection.MakeClass(). 82def MakeClass(descriptor): 83 """Construct a class object for a protobuf described by descriptor. 84 85 DEPRECATED: use MessageFactory.GetPrototype() instead. 86 87 Args: 88 descriptor: A descriptor.Descriptor object describing the protobuf. 89 Returns: 90 The Message class object described by the descriptor. 91 """ 92 # Original implementation leads to duplicate message classes, which won't play 93 # well with extensions. Message factory info is also missing. 94 # Redirect to message_factory. 95 return symbol_database.Default().GetPrototype(descriptor) 96