Initial checkin.
diff --git a/python/google/protobuf/message.py b/python/google/protobuf/message.py
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+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.
+# http://code.google.com/p/protobuf/
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# 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)'
+
+from google.protobuf import text_format
+
+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 __eq__(self, other_msg):
+ 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 __str__(self):
+ return text_format.MessageToString(self)
+
+ def MergeFrom(self, other_msg):
+ raise NotImplementedError
+
+ def CopyFrom(self, other_msg):
+ raise NotImplementedError
+
+ def Clear(self):
+ raise NotImplementedError
+
+ def IsInitialized(self):
+ 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):
+ """Like MergeFromString(), except we clear the object first."""
+ self.Clear()
+ self.MergeFromString(serialized)
+
+ def SerializeToString(self):
+ 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, field_name):
+ """Returns a list of (FieldDescriptor, value) tuples for all
+ fields in the message which are not empty. A singular field is non-empty
+ if HasField() would return true, and 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):
+ raise NotImplementedError
+
+ def ClearField(self, field_name):
+ raise NotImplementedError
+
+ def HasExtension(self, extension_handle):
+ raise NotImplementedError
+
+ def ClearExtension(self, extension_handle):
+ 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