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"""Provides a factory class for generating dynamic messages.9 10The easiest way to use this class is if you have access to the FileDescriptor11protos containing the messages you want to create you can just do the following:12 13message_classes = message_factory.GetMessages(iterable_of_file_descriptors)14my_proto_instance = message_classes['some.proto.package.MessageName']()15"""16 17__author__ = 'matthewtoia@google.com (Matt Toia)'18 19import warnings20 21from google.protobuf import descriptor_pool22from google.protobuf import message23from google.protobuf.internal import api_implementation24 25if api_implementation.Type() == 'python':26  from google.protobuf.internal import python_message as message_impl27else:28  from google.protobuf.pyext import cpp_message as message_impl  # pylint: disable=g-import-not-at-top29 30 31# The type of all Message classes.32_GENERATED_PROTOCOL_MESSAGE_TYPE = message_impl.GeneratedProtocolMessageType33 34 35def GetMessageClass(descriptor):36  """Obtains a proto2 message class based on the passed in descriptor.37 38  Passing a descriptor with a fully qualified name matching a previous39  invocation will cause the same class to be returned.40 41  Args:42    descriptor: The descriptor to build from.43 44  Returns:45    A class describing the passed in descriptor.46  """47  concrete_class = getattr(descriptor, '_concrete_class', None)48  if concrete_class:49    return concrete_class50  return _InternalCreateMessageClass(descriptor)51 52 53def GetMessageClassesForFiles(files, pool):54  """Gets all the messages from specified files.55 56  This will find and resolve dependencies, failing if the descriptor57  pool cannot satisfy them.58 59  This will not return the classes for nested types within those classes, for60  those, use GetMessageClass() on the nested types within their containing61  messages.62 63  For example, for the message:64 65  message NestedTypeMessage {66    message NestedType {67      string data = 1;68    }69    NestedType nested = 1;70  }71 72  NestedTypeMessage will be in the result, but not73  NestedTypeMessage.NestedType.74 75  Args:76    files: The file names to extract messages from.77    pool: The descriptor pool to find the files including the dependent files.78 79  Returns:80    A dictionary mapping proto names to the message classes.81  """82  result = {}83  for file_name in files:84    file_desc = pool.FindFileByName(file_name)85    for desc in file_desc.message_types_by_name.values():86      result[desc.full_name] = GetMessageClass(desc)87 88    # While the extension FieldDescriptors are created by the descriptor pool,89    # the python classes created in the factory need them to be registered90    # explicitly, which is done below.91    #92    # The call to RegisterExtension will specifically check if the93    # extension was already registered on the object and either94    # ignore the registration if the original was the same, or raise95    # an error if they were different.96 97    for extension in file_desc.extensions_by_name.values():98      _ = GetMessageClass(extension.containing_type)99      if api_implementation.Type() != 'python':100        # TODO: Remove this check here. Duplicate extension101        # register check should be in descriptor_pool.102        if extension is not pool.FindExtensionByNumber(103            extension.containing_type, extension.number104        ):105          raise ValueError('Double registration of Extensions')106      # Recursively load protos for extension field, in order to be able to107      # fully represent the extension. This matches the behavior for regular108      # fields too.109      if extension.message_type:110        GetMessageClass(extension.message_type)111  return result112 113 114def _InternalCreateMessageClass(descriptor):115  """Builds a proto2 message class based on the passed in descriptor.116 117  Args:118    descriptor: The descriptor to build from.119 120  Returns:121    A class describing the passed in descriptor.122  """123  descriptor_name = descriptor.name124  result_class = _GENERATED_PROTOCOL_MESSAGE_TYPE(125      descriptor_name,126      (message.Message,),127      {128          'DESCRIPTOR': descriptor,129          # If module not set, it wrongly points to message_factory module.130          '__module__': None,131      },132  )133  for field in descriptor.fields:134    if field.message_type:135      GetMessageClass(field.message_type)136 137  for extension in result_class.DESCRIPTOR.extensions:138    extended_class = GetMessageClass(extension.containing_type)139    if api_implementation.Type() != 'python':140      # TODO: Remove this check here. Duplicate extension141      # register check should be in descriptor_pool.142      pool = extension.containing_type.file.pool143      if extension is not pool.FindExtensionByNumber(144          extension.containing_type, extension.number145      ):146        raise ValueError('Double registration of Extensions')147    if extension.message_type:148      GetMessageClass(extension.message_type)149  return result_class150 151 152# Deprecated. Please use GetMessageClass() or GetMessageClassesForFiles()153# method above instead.154class MessageFactory(object):155  """Factory for creating Proto2 messages from descriptors in a pool."""156 157  def __init__(self, pool=None):158    """Initializes a new factory."""159    self.pool = pool or descriptor_pool.DescriptorPool()160 161 162def GetMessages(file_protos, pool=None):163  """Builds a dictionary of all the messages available in a set of files.164 165  Args:166    file_protos: Iterable of FileDescriptorProto to build messages out of.167    pool: The descriptor pool to add the file protos.168 169  Returns:170    A dictionary mapping proto names to the message classes. This will include171    any dependent messages as well as any messages defined in the same file as172    a specified message.173  """174  # The cpp implementation of the protocol buffer library requires to add the175  # message in topological order of the dependency graph.176  des_pool = pool or descriptor_pool.DescriptorPool()177  file_by_name = {file_proto.name: file_proto for file_proto in file_protos}178 179  def _AddFile(file_proto):180    for dependency in file_proto.dependency:181      if dependency in file_by_name:182        # Remove from elements to be visited, in order to cut cycles.183        _AddFile(file_by_name.pop(dependency))184    des_pool.Add(file_proto)185 186  while file_by_name:187    _AddFile(file_by_name.popitem()[1])188  return GetMessageClassesForFiles(189      [file_proto.name for file_proto in file_protos], des_pool190  )191