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| # Protocol Buffers - Google's data interchange format | |
| # Copyright 2008 Google Inc. All rights reserved. | |
| # https://developers.google.com/protocol-buffers/ | |
| # | |
| # Redistribution and use in source and binary forms, with or without | |
| # modification, are permitted provided that the following conditions are | |
| # met: | |
| # | |
| # * Redistributions of source code must retain the above copyright | |
| # notice, this list of conditions and the following disclaimer. | |
| # * Redistributions in binary form must reproduce the above | |
| # copyright notice, this list of conditions and the following disclaimer | |
| # in the documentation and/or other materials provided with the | |
| # distribution. | |
| # * Neither the name of Google Inc. nor the names of its | |
| # contributors may be used to endorse or promote products derived from | |
| # this software without specific prior written permission. | |
| # | |
| # THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| # "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| # LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| # A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| # OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| # SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| # LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| # DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| # THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| # (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| """Provides a factory class for generating dynamic messages. | |
| The easiest way to use this class is if you have access to the FileDescriptor | |
| protos containing the messages you want to create you can just do the following: | |
| message_classes = message_factory.GetMessages(iterable_of_file_descriptors) | |
| my_proto_instance = message_classes['some.proto.package.MessageName']() | |
| """ | |
| __author__ = '[email protected] (Matt Toia)' | |
| from google.protobuf.internal import api_implementation | |
| from google.protobuf import descriptor_pool | |
| from google.protobuf import message | |
| if api_implementation.Type() == 'cpp': | |
| from google.protobuf.pyext import cpp_message as message_impl | |
| else: | |
| from google.protobuf.internal import python_message as message_impl | |
| # The type of all Message classes. | |
| _GENERATED_PROTOCOL_MESSAGE_TYPE = message_impl.GeneratedProtocolMessageType | |
| class MessageFactory(object): | |
| """Factory for creating Proto2 messages from descriptors in a pool.""" | |
| def __init__(self, pool=None): | |
| """Initializes a new factory.""" | |
| self.pool = pool or descriptor_pool.DescriptorPool() | |
| # local cache of all classes built from protobuf descriptors | |
| self._classes = {} | |
| def GetPrototype(self, descriptor): | |
| """Obtains a proto2 message class based on the passed in descriptor. | |
| Passing a descriptor with a fully qualified name matching a previous | |
| invocation will cause the same class to be returned. | |
| Args: | |
| descriptor: The descriptor to build from. | |
| Returns: | |
| A class describing the passed in descriptor. | |
| """ | |
| if descriptor not in self._classes: | |
| result_class = self.CreatePrototype(descriptor) | |
| # The assignment to _classes is redundant for the base implementation, but | |
| # might avoid confusion in cases where CreatePrototype gets overridden and | |
| # does not call the base implementation. | |
| self._classes[descriptor] = result_class | |
| return result_class | |
| return self._classes[descriptor] | |
| def CreatePrototype(self, descriptor): | |
| """Builds a proto2 message class based on the passed in descriptor. | |
| Don't call this function directly, it always creates a new class. Call | |
| GetPrototype() instead. This method is meant to be overridden in subblasses | |
| to perform additional operations on the newly constructed class. | |
| Args: | |
| descriptor: The descriptor to build from. | |
| Returns: | |
| A class describing the passed in descriptor. | |
| """ | |
| descriptor_name = descriptor.name | |
| result_class = _GENERATED_PROTOCOL_MESSAGE_TYPE( | |
| descriptor_name, | |
| (message.Message,), | |
| { | |
| 'DESCRIPTOR': descriptor, | |
| # If module not set, it wrongly points to message_factory module. | |
| '__module__': None, | |
| }) | |
| result_class._FACTORY = self # pylint: disable=protected-access | |
| # Assign in _classes before doing recursive calls to avoid infinite | |
| # recursion. | |
| self._classes[descriptor] = result_class | |
| for field in descriptor.fields: | |
| if field.message_type: | |
| self.GetPrototype(field.message_type) | |
| for extension in result_class.DESCRIPTOR.extensions: | |
| if extension.containing_type not in self._classes: | |
| self.GetPrototype(extension.containing_type) | |
| extended_class = self._classes[extension.containing_type] | |
| extended_class.RegisterExtension(extension) | |
| return result_class | |
| def GetMessages(self, files): | |
| """Gets all the messages from a specified file. | |
| This will find and resolve dependencies, failing if the descriptor | |
| pool cannot satisfy them. | |
| Args: | |
| files: The file names to extract messages from. | |
| Returns: | |
| A dictionary mapping proto names to the message classes. This will include | |
| any dependent messages as well as any messages defined in the same file as | |
| a specified message. | |
| """ | |
| result = {} | |
| for file_name in files: | |
| file_desc = self.pool.FindFileByName(file_name) | |
| for desc in file_desc.message_types_by_name.values(): | |
| result[desc.full_name] = self.GetPrototype(desc) | |
| # While the extension FieldDescriptors are created by the descriptor pool, | |
| # the python classes created in the factory need them to be registered | |
| # explicitly, which is done below. | |
| # | |
| # The call to RegisterExtension will specifically check if the | |
| # extension was already registered on the object and either | |
| # ignore the registration if the original was the same, or raise | |
| # an error if they were different. | |
| for extension in file_desc.extensions_by_name.values(): | |
| if extension.containing_type not in self._classes: | |
| self.GetPrototype(extension.containing_type) | |
| extended_class = self._classes[extension.containing_type] | |
| extended_class.RegisterExtension(extension) | |
| return result | |
| _FACTORY = MessageFactory() | |
| def GetMessages(file_protos): | |
| """Builds a dictionary of all the messages available in a set of files. | |
| Args: | |
| file_protos: Iterable of FileDescriptorProto to build messages out of. | |
| Returns: | |
| A dictionary mapping proto names to the message classes. This will include | |
| any dependent messages as well as any messages defined in the same file as | |
| a specified message. | |
| """ | |
| # The cpp implementation of the protocol buffer library requires to add the | |
| # message in topological order of the dependency graph. | |
| file_by_name = {file_proto.name: file_proto for file_proto in file_protos} | |
| def _AddFile(file_proto): | |
| for dependency in file_proto.dependency: | |
| if dependency in file_by_name: | |
| # Remove from elements to be visited, in order to cut cycles. | |
| _AddFile(file_by_name.pop(dependency)) | |
| _FACTORY.pool.Add(file_proto) | |
| while file_by_name: | |
| _AddFile(file_by_name.popitem()[1]) | |
| return _FACTORY.GetMessages([file_proto.name for file_proto in file_protos]) | |