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# Protocol Buffers - Google's data interchange format
# Copyright 2008 Google Inc. All rights reserved.
#
# Use of this source code is governed by a BSD-style
# license that can be found in the LICENSE file or at
# https://developers.google.com/open-source/licenses/bsd
"""A database of Python protocol buffer generated symbols.
SymbolDatabase is the MessageFactory for messages generated at compile time,
and makes it easy to create new instances of a registered type, given only the
type's protocol buffer symbol name.
Example usage::
db = symbol_database.SymbolDatabase()
# Register symbols of interest, from one or multiple files.
db.RegisterFileDescriptor(my_proto_pb2.DESCRIPTOR)
db.RegisterMessage(my_proto_pb2.MyMessage)
db.RegisterEnumDescriptor(my_proto_pb2.MyEnum.DESCRIPTOR)
# The database can be used as a MessageFactory, to generate types based on
# their name:
types = db.GetMessages(['my_proto.proto'])
my_message_instance = types['MyMessage']()
# The database's underlying descriptor pool can be queried, so it's not
# necessary to know a type's filename to be able to generate it:
filename = db.pool.FindFileContainingSymbol('MyMessage')
my_message_instance = db.GetMessages([filename])['MyMessage']()
# This functionality is also provided directly via a convenience method:
my_message_instance = db.GetSymbol('MyMessage')()
"""
import warnings
from google.protobuf.internal import api_implementation
from google.protobuf import descriptor_pool
from google.protobuf import message_factory
class SymbolDatabase():
"""A database of Python generated symbols."""
# local cache of registered classes.
_classes = {}
def __init__(self, pool=None):
"""Initializes a new SymbolDatabase."""
self.pool = pool or descriptor_pool.DescriptorPool()
def GetPrototype(self, descriptor):
warnings.warn('SymbolDatabase.GetPrototype() is deprecated. Please '
'use message_factory.GetMessageClass() instead. '
'SymbolDatabase.GetPrototype() will be removed soon.')
return message_factory.GetMessageClass(descriptor)
def CreatePrototype(self, descriptor):
warnings.warn('Directly call CreatePrototype() is wrong. Please use '
'message_factory.GetMessageClass() instead. '
'SymbolDatabase.CreatePrototype() will be removed soon.')
return message_factory._InternalCreateMessageClass(descriptor)
def GetMessages(self, files):
warnings.warn('SymbolDatabase.GetMessages() is deprecated. Please use '
'message_factory.GetMessageClassedForFiles() instead. '
'SymbolDatabase.GetMessages() will be removed soon.')
return message_factory.GetMessageClassedForFiles(files, self.pool)
def RegisterMessage(self, message):
"""Registers the given message type in the local database.
Calls to GetSymbol() and GetMessages() will return messages registered here.
Args:
message: A :class:`google.protobuf.message.Message` subclass (or
instance); its descriptor will be registered.
Returns:
The provided message.
"""
desc = message.DESCRIPTOR
self._classes[desc] = message
self.RegisterMessageDescriptor(desc)
return message
def RegisterMessageDescriptor(self, message_descriptor):
"""Registers the given message descriptor in the local database.
Args:
message_descriptor (Descriptor): the message descriptor to add.
"""
if api_implementation.Type() == 'python':
# pylint: disable=protected-access
self.pool._AddDescriptor(message_descriptor)
def RegisterEnumDescriptor(self, enum_descriptor):
"""Registers the given enum descriptor in the local database.
Args:
enum_descriptor (EnumDescriptor): The enum descriptor to register.
Returns:
EnumDescriptor: The provided descriptor.
"""
if api_implementation.Type() == 'python':
# pylint: disable=protected-access
self.pool._AddEnumDescriptor(enum_descriptor)
return enum_descriptor
def RegisterServiceDescriptor(self, service_descriptor):
"""Registers the given service descriptor in the local database.
Args:
service_descriptor (ServiceDescriptor): the service descriptor to
register.
"""
if api_implementation.Type() == 'python':
# pylint: disable=protected-access
self.pool._AddServiceDescriptor(service_descriptor)
def RegisterFileDescriptor(self, file_descriptor):
"""Registers the given file descriptor in the local database.
Args:
file_descriptor (FileDescriptor): The file descriptor to register.
"""
if api_implementation.Type() == 'python':
# pylint: disable=protected-access
self.pool._InternalAddFileDescriptor(file_descriptor)
def GetSymbol(self, symbol):
"""Tries to find a symbol in the local database.
Currently, this method only returns message.Message instances, however, if
may be extended in future to support other symbol types.
Args:
symbol (str): a protocol buffer symbol.
Returns:
A Python class corresponding to the symbol.
Raises:
KeyError: if the symbol could not be found.
"""
return self._classes[self.pool.FindMessageTypeByName(symbol)]
def GetMessages(self, files):
# TODO: Fix the differences with MessageFactory.
"""Gets all registered messages from a specified file.
Only messages already created and registered will be returned; (this is the
case for imported _pb2 modules)
But unlike MessageFactory, this version also returns already defined nested
messages, but does not register any message extensions.
Args:
files (list[str]): The file names to extract messages from.
Returns:
A dictionary mapping proto names to the message classes.
Raises:
KeyError: if a file could not be found.
"""
def _GetAllMessages(desc):
"""Walk a message Descriptor and recursively yields all message names."""
yield desc
for msg_desc in desc.nested_types:
for nested_desc in _GetAllMessages(msg_desc):
yield nested_desc
result = {}
for file_name in files:
file_desc = self.pool.FindFileByName(file_name)
for msg_desc in file_desc.message_types_by_name.values():
for desc in _GetAllMessages(msg_desc):
try:
result[desc.full_name] = self._classes[desc]
except KeyError:
# This descriptor has no registered class, skip it.
pass
return result
_DEFAULT = SymbolDatabase(pool=descriptor_pool.Default())
def Default():
"""Returns the default SymbolDatabase."""
return _DEFAULT
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