| # Protocol Buffers - Google's data interchange format |
| # Copyright 2008 Google Inc. All rights reserved. |
| # https://developers.google.com/protocol-buffers/ |
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| |
| """A database of Python protocol buffer generated symbols. |
| |
| SymbolDatabase makes it easy to create new instances of a registered type, given |
| only the type's protocol buffer symbol name. Once all symbols are registered, |
| they can be accessed using either the MessageFactory interface which |
| SymbolDatabase exposes, or the DescriptorPool interface of the underlying |
| pool. |
| |
| 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')() |
| """ |
| |
| |
| from google.protobuf import descriptor_pool |
| |
| |
| class SymbolDatabase(object): |
| """A database of Python generated symbols. |
| |
| SymbolDatabase also models message_factory.MessageFactory. |
| |
| The symbol database can be used to keep a global registry of all protocol |
| buffer types used within a program. |
| """ |
| |
| def __init__(self, pool=None): |
| """Constructor.""" |
| |
| self._symbols = {} |
| self._symbols_by_file = {} |
| self.pool = pool or descriptor_pool.Default() |
| |
| def RegisterMessage(self, message): |
| """Registers the given message type in the local database. |
| |
| Args: |
| message: a message.Message, to be registered. |
| |
| Returns: |
| The provided message. |
| """ |
| |
| desc = message.DESCRIPTOR |
| self._symbols[desc.full_name] = message |
| if desc.file.name not in self._symbols_by_file: |
| self._symbols_by_file[desc.file.name] = {} |
| self._symbols_by_file[desc.file.name][desc.full_name] = message |
| self.pool.AddDescriptor(desc) |
| return message |
| |
| def RegisterEnumDescriptor(self, enum_descriptor): |
| """Registers the given enum descriptor in the local database. |
| |
| Args: |
| enum_descriptor: a descriptor.EnumDescriptor. |
| |
| Returns: |
| The provided descriptor. |
| """ |
| self.pool.AddEnumDescriptor(enum_descriptor) |
| return enum_descriptor |
| |
| def RegisterFileDescriptor(self, file_descriptor): |
| """Registers the given file descriptor in the local database. |
| |
| Args: |
| file_descriptor: a descriptor.FileDescriptor. |
| |
| Returns: |
| The provided descriptor. |
| """ |
| self.pool.AddFileDescriptor(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: A str, a protocol buffer symbol. |
| |
| Returns: |
| A Python class corresponding to the symbol. |
| |
| Raises: |
| KeyError: if the symbol could not be found. |
| """ |
| |
| return self._symbols[symbol] |
| |
| def GetPrototype(self, descriptor): |
| """Builds 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. |
| """ |
| |
| return self.GetSymbol(descriptor.full_name) |
| |
| def GetMessages(self, files): |
| """Gets all the messages from a specified file. |
| |
| This will find and resolve dependencies, failing if they are not registered |
| in the symbol database. |
| |
| |
| 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. |
| |
| Raises: |
| KeyError: if a file could not be found. |
| """ |
| |
| result = {} |
| for f in files: |
| result.update(self._symbols_by_file[f]) |
| return result |
| |
| _DEFAULT = SymbolDatabase(pool=descriptor_pool.Default()) |
| |
| |
| def Default(): |
| """Returns the default SymbolDatabase.""" |
| return _DEFAULT |