File Content: message.py # 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. # TODO(robinson): We should just make these methods all "pure-virtual" and move # all implementation out, into reflection.py for now. """Contains an abstract base class for protocol messages.""" __author__ = 'robinson@google.com (Will Robinson)' class Error(Exception): pass class DecodeError(Error): pass class EncodeError(Error): pass class Message(object): """Abstract base class for protocol messages. Protocol message classes are almost always generated by the protocol compiler. These generated types subclass Message and implement the methods shown below. TODO(robinson): Link to an HTML document here. TODO(robinson): Document that instances of this class will also have an Extensions attribute with __getitem__ and __setitem__. Again, not sure how to best convey this. TODO(robinson): Document that the class must also have a static RegisterExtension(extension_field) method. Not sure how to best express at this point. """ # TODO(robinson): Document these fields and methods. __slots__ = [] DESCRIPTOR = None def __deepcopy__(self, memo=None): clone = type(self)() clone.MergeFrom(self) return clone def __eq__(self, other_msg): """Recursively compares two messages by value and structure.""" raise NotImplementedError def __ne__(self, other_msg): # Can't just say self != other_msg, since that would infinitely recurse. :) return not self == other_msg def __hash__(self): raise TypeError('unhashable object') def __str__(self): """Outputs a human-readable representation of the message.""" raise NotImplementedError def __unicode__(self): """Outputs a human-readable representation of the message.""" raise NotImplementedError def MergeFrom(self, other_msg): """Merges the contents of the specified message into current message. This method merges the contents of the specified message into the current message. Singular fields that are set in the specified message overwrite the corresponding fields in the current message. Repeated fields are appended. Singular sub-messages and groups are recursively merged. Args: other_msg: Message to merge into the current message. """ raise NotImplementedError def CopyFrom(self, other_msg): """Copies the content of the specified message into the current message. The method clears the current message and then merges the specified message using MergeFrom. Args: other_msg: Message to copy into the current one. """ if self is other_msg: return self.Clear() self.MergeFrom(other_msg) def Clear(self): """Clears all data that was set in the message.""" raise NotImplementedError def SetInParent(self): """Mark this as present in the parent. This normally happens automatically when you assign a field of a sub-message, but sometimes you want to make the sub-message present while keeping it empty. If you find yourself using this, you may want to reconsider your design.""" raise NotImplementedError def IsInitialized(self): """Checks if the message is initialized. Returns: The method returns True if the message is initialized (i.e. all of its required fields are set). """ raise NotImplementedError # TODO(robinson): MergeFromString() should probably return None and be # implemented in terms of a helper that returns the # of bytes read. Our # deserialization routines would use the helper when recursively # deserializing, but the end user would almost always just want the no-return # MergeFromString(). def MergeFromString(self, serialized): """Merges serialized protocol buffer data into this message. When we find a field in |serialized| that is already present in this message: - If it's a "repeated" field, we append to the end of our list. - Else, if it's a scalar, we overwrite our field. - Else, (it's a nonrepeated composite), we recursively merge into the existing composite. TODO(robinson): Document handling of unknown fields. Args: serialized: Any object that allows us to call buffer(serialized) to access a string of bytes using the buffer interface. TODO(robinson): When we switch to a helper, this will return None. Returns: The number of bytes read from |serialized|. For non-group messages, this will always be len(serialized), but for messages which are actually groups, this will generally be less than len(serialized), since we must stop when we reach an END_GROUP tag. Note that if we *do* stop because of an END_GROUP tag, the number of bytes returned does not include the bytes for the END_GROUP tag information. """ raise NotImplementedError def ParseFromString(self, serialized): """Parse serialized protocol buffer data into this message. Like MergeFromString(), except we clear the object first and do not return the value that MergeFromString returns. """ self.Clear() self.MergeFromString(serialized) def SerializeToString(self, **kwargs): """Serializes the protocol message to a binary string. Arguments: **kwargs: Keyword arguments to the serialize method, accepts the following keyword args: deterministic: If true, requests deterministic serialization of the protobuf, with predictable ordering of map keys. Returns: A binary string representation of the message if all of the required fields in the message are set (i.e. the message is initialized). Raises: message.EncodeError if the message isn't initialized. """ raise NotImplementedError def SerializePartialToString(self, **kwargs): """Serializes the protocol message to a binary string. This method is similar to SerializeToString but doesn't check if the message is initialized. Arguments: **kwargs: Keyword arguments to the serialize method, accepts the following keyword args: deterministic: If true, requests deterministic serialization of the protobuf, with predictable ordering of map keys. Returns: A string representation of the partial message. """ raise NotImplementedError # TODO(robinson): Decide whether we like these better # than auto-generated has_foo() and clear_foo() methods # on the instances themselves. This way is less consistent # with C++, but it makes reflection-type access easier and # reduces the number of magically autogenerated things. # # TODO(robinson): Be sure to document (and test) exactly # which field names are accepted here. Are we case-sensitive? # What do we do with fields that share names with Python keywords # like 'lambda' and 'yield'? # # nnorwitz says: # """ # Typically (in python), an underscore is appended to names that are # keywords. So they would become lambda_ or yield_. # """ def ListFields(self): """Returns a list of (FieldDescriptor, value) tuples for all fields in the message which are not empty. A message field is non-empty if HasField() would return true. A singular primitive field is non-empty if HasField() would return true in proto2 or it is non zero in proto3. A repeated field is non-empty if it contains at least one element. The fields are ordered by field number""" raise NotImplementedError def HasField(self, field_name): """Checks if a certain field is set for the message, or if any field inside a oneof group is set. Note that if the field_name is not defined in the message descriptor, ValueError will be raised.""" raise NotImplementedError def ClearField(self, field_name): """Clears the contents of a given field, or the field set inside a oneof group. If the name neither refers to a defined field or oneof group, ValueError is raised.""" raise NotImplementedError def WhichOneof(self, oneof_group): """Returns the name of the field that is set inside a oneof group, or None if no field is set. If no group with the given name exists, ValueError will be raised.""" raise NotImplementedError def HasExtension(self, extension_handle): raise NotImplementedError def ClearExtension(self, extension_handle): raise NotImplementedError def DiscardUnknownFields(self): raise NotImplementedError def ByteSize(self): """Returns the serialized size of this message. Recursively calls ByteSize() on all contained messages. """ raise NotImplementedError def _SetListener(self, message_listener): """Internal method used by the protocol message implementation. Clients should not call this directly. Sets a listener that this message will call on certain state transitions. The purpose of this method is to register back-edges from children to parents at runtime, for the purpose of setting "has" bits and byte-size-dirty bits in the parent and ancestor objects whenever a child or descendant object is modified. If the client wants to disconnect this Message from the object tree, she explicitly sets callback to None. If message_listener is None, unregisters any existing listener. Otherwise, message_listener must implement the MessageListener interface in internal/message_listener.py, and we discard any listener registered via a previous _SetListener() call. """ raise NotImplementedError def __getstate__(self): """Support the pickle protocol.""" return dict(serialized=self.SerializePartialToString()) def __setstate__(self, state): """Support the pickle protocol.""" self.__init__() self.ParseFromString(state['serialized']) Submit