diff options
Diffstat (limited to 'generator/google/protobuf/reflection.py')
| -rw-r--r-- | generator/google/protobuf/reflection.py | 139 |
1 files changed, 42 insertions, 97 deletions
diff --git a/generator/google/protobuf/reflection.py b/generator/google/protobuf/reflection.py index 9570fd5..51c8332 100644 --- a/generator/google/protobuf/reflection.py +++ b/generator/google/protobuf/reflection.py @@ -1,6 +1,6 @@ # Protocol Buffers - Google's data interchange format # Copyright 2008 Google Inc. All rights reserved. -# http://code.google.com/p/protobuf/ +# 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 @@ -49,104 +49,17 @@ __author__ = 'robinson@google.com (Will Robinson)' from google.protobuf.internal import api_implementation -from google.protobuf import descriptor as descriptor_mod from google.protobuf import message -_FieldDescriptor = descriptor_mod.FieldDescriptor - if api_implementation.Type() == 'cpp': - if api_implementation.Version() == 2: - from google.protobuf.internal.cpp import cpp_message - _NewMessage = cpp_message.NewMessage - _InitMessage = cpp_message.InitMessage - else: - from google.protobuf.internal import cpp_message - _NewMessage = cpp_message.NewMessage - _InitMessage = cpp_message.InitMessage + from google.protobuf.pyext import cpp_message as message_impl else: - from google.protobuf.internal import python_message - _NewMessage = python_message.NewMessage - _InitMessage = python_message.InitMessage - - -class GeneratedProtocolMessageType(type): + from google.protobuf.internal import python_message as message_impl - """Metaclass for protocol message classes created at runtime from Descriptors. - - We add implementations for all methods described in the Message class. We - also create properties to allow getting/setting all fields in the protocol - message. Finally, we create slots to prevent users from accidentally - "setting" nonexistent fields in the protocol message, which then wouldn't get - serialized / deserialized properly. - - The protocol compiler currently uses this metaclass to create protocol - message classes at runtime. Clients can also manually create their own - classes at runtime, as in this example: - - mydescriptor = Descriptor(.....) - class MyProtoClass(Message): - __metaclass__ = GeneratedProtocolMessageType - DESCRIPTOR = mydescriptor - myproto_instance = MyProtoClass() - myproto.foo_field = 23 - ... - """ - - # Must be consistent with the protocol-compiler code in - # proto2/compiler/internal/generator.*. - _DESCRIPTOR_KEY = 'DESCRIPTOR' - - def __new__(cls, name, bases, dictionary): - """Custom allocation for runtime-generated class types. - - We override __new__ because this is apparently the only place - where we can meaningfully set __slots__ on the class we're creating(?). - (The interplay between metaclasses and slots is not very well-documented). - - Args: - name: Name of the class (ignored, but required by the - metaclass protocol). - bases: Base classes of the class we're constructing. - (Should be message.Message). We ignore this field, but - it's required by the metaclass protocol - dictionary: The class dictionary of the class we're - constructing. dictionary[_DESCRIPTOR_KEY] must contain - a Descriptor object describing this protocol message - type. - - Returns: - Newly-allocated class. - """ - descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY] - bases = _NewMessage(bases, descriptor, dictionary) - superclass = super(GeneratedProtocolMessageType, cls) - - new_class = superclass.__new__(cls, name, bases, dictionary) - setattr(descriptor, '_concrete_class', new_class) - return new_class - - def __init__(cls, name, bases, dictionary): - """Here we perform the majority of our work on the class. - We add enum getters, an __init__ method, implementations - of all Message methods, and properties for all fields - in the protocol type. - - Args: - name: Name of the class (ignored, but required by the - metaclass protocol). - bases: Base classes of the class we're constructing. - (Should be message.Message). We ignore this field, but - it's required by the metaclass protocol - dictionary: The class dictionary of the class we're - constructing. dictionary[_DESCRIPTOR_KEY] must contain - a Descriptor object describing this protocol message - type. - """ - descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY] - _InitMessage(descriptor, cls) - superclass = super(GeneratedProtocolMessageType, cls) - superclass.__init__(name, bases, dictionary) +# The type of all Message classes. +# Part of the public interface, but normally only used by message factories. +GeneratedProtocolMessageType = message_impl.GeneratedProtocolMessageType def ParseMessage(descriptor, byte_str): @@ -159,11 +72,43 @@ def ParseMessage(descriptor, byte_str): Returns: Newly created protobuf Message object. """ + result_class = MakeClass(descriptor) + new_msg = result_class() + new_msg.ParseFromString(byte_str) + return new_msg - class _ResultClass(message.Message): + +def MakeClass(descriptor): + """Construct a class object for a protobuf described by descriptor. + + Composite descriptors are handled by defining the new class as a member of the + parent class, recursing as deep as necessary. + This is the dynamic equivalent to: + + class Parent(message.Message): __metaclass__ = GeneratedProtocolMessageType DESCRIPTOR = descriptor + class Child(message.Message): + __metaclass__ = GeneratedProtocolMessageType + DESCRIPTOR = descriptor.nested_types[0] - new_msg = _ResultClass() - new_msg.ParseFromString(byte_str) - return new_msg + Sample usage: + file_descriptor = descriptor_pb2.FileDescriptorProto() + file_descriptor.ParseFromString(proto2_string) + msg_descriptor = descriptor.MakeDescriptor(file_descriptor.message_type[0]) + msg_class = reflection.MakeClass(msg_descriptor) + msg = msg_class() + + Args: + descriptor: A descriptor.Descriptor object describing the protobuf. + Returns: + The Message class object described by the descriptor. + """ + attributes = {} + for name, nested_type in descriptor.nested_types_by_name.items(): + attributes[name] = MakeClass(nested_type) + + attributes[GeneratedProtocolMessageType._DESCRIPTOR_KEY] = descriptor + + return GeneratedProtocolMessageType(str(descriptor.name), (message.Message,), + attributes) |