Submit recent changes from internal branch. See CHANGES.txt for more details.

19 files changed, 4871 insertions, 1149 deletions

diff --git a/python/google/protobuf/descriptor.py b/python/google/protobuf/descriptor.py
index aa4ab969..cf609bee 100755
--- a/python/google/protobuf/descriptor.py
+++ b/python/google/protobuf/descriptor.py
@@ -28,16 +28,6 @@
 # (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 probably need to provide deep-copy methods for
-# descriptor types.  When a FieldDescriptor is passed into
-# Descriptor.__init__(), we should make a deep copy and then set
-# containing_type on it.  Alternatively, we could just get
-# rid of containing_type (iit's not needed for reflection.py, at least).
-#
-# TODO(robinson): Print method?
-#
-# TODO(robinson): Useful __repr__?
-
 """Descriptors essentially contain exactly the information found in a .proto
 file, in types that make this information accessible in Python.
 """
@@ -45,6 +35,13 @@ file, in types that make this information accessible in Python.
 __author__ = 'robinson@google.com (Will Robinson)'
 
 
+from google.protobuf.internal import api_implementation
+
+
+if api_implementation.Type() == 'cpp':
+  from google.protobuf.internal import cpp_message
+
+
 class Error(Exception):
   """Base error for this module."""
 
@@ -396,6 +393,13 @@ class FieldDescriptor(DescriptorBase):
     self.enum_type = enum_type
     self.is_extension = is_extension
     self.extension_scope = extension_scope
+    if api_implementation.Type() == 'cpp':
+      if is_extension:
+        self._cdescriptor = cpp_message.GetExtensionDescriptor(full_name)
+      else:
+        self._cdescriptor = cpp_message.GetFieldDescriptor(full_name)
+    else:
+      self._cdescriptor = None
 
 
 class EnumDescriptor(_NestedDescriptorBase):
@@ -567,9 +571,13 @@ class FileDescriptor(DescriptorBase):
     """Constructor."""
     super(FileDescriptor, self).__init__(options, 'FileOptions')
 
+    self.message_types_by_name = {}
     self.name = name
     self.package = package
     self.serialized_pb = serialized_pb
+    if (api_implementation.Type() == 'cpp' and
+        self.serialized_pb is not None):
+      cpp_message.BuildFile(self.serialized_pb)
 
   def CopyToProto(self, proto):
     """Copies this to a descriptor_pb2.FileDescriptorProto.
diff --git a/python/google/protobuf/internal/api_implementation.py b/python/google/protobuf/internal/api_implementation.py
new file mode 100755
index 00000000..b3e412e2
--- /dev/null
+++ b/python/google/protobuf/internal/api_implementation.py
@@ -0,0 +1,64 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# 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.
+
+"""
+This module is the central entity that determines which implementation of the
+API is used.
+"""
+
+__author__ = 'petar@google.com (Petar Petrov)'
+
+import os
+# This environment variable can be used to switch to a certain implementation
+# of the Python API. Right now only 'python' and 'cpp' are valid values. Any
+# other value will be ignored.
+_implementation_type = os.getenv('PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION',
+                                 'python')
+
+
+if _implementation_type != 'python':
+  # For now, by default use the pure-Python implementation.
+  # The code below checks if the C extension is available and
+  # uses it if it is available.
+  _implementation_type = 'cpp'
+  ## Determine automatically which implementation to use.
+  #try:
+  #  from google.protobuf.internal import cpp_message
+  #  _implementation_type = 'cpp'
+  #except ImportError, e:
+  #  _implementation_type = 'python'
+
+
+# Usage of this function is discouraged. Clients shouldn't care which
+# implementation of the API is in use. Note that there is no guarantee
+# that differences between APIs will be maintained.
+# Please don't use this function if possible.
+def Type():
+  return _implementation_type
diff --git a/python/google/protobuf/internal/containers.py b/python/google/protobuf/internal/containers.py
index 5cc7d6d0..097a3c26 100755
--- a/python/google/protobuf/internal/containers.py
+++ b/python/google/protobuf/internal/containers.py
@@ -72,9 +72,15 @@ class BaseContainer(object):
     # The concrete classes should define __eq__.
     return not self == other
 
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
   def __repr__(self):
     return repr(self._values)
 
+  def sort(self, sort_function=cmp):
+    self._values.sort(sort_function)
+
 
 class RepeatedScalarFieldContainer(BaseContainer):
 
@@ -198,28 +204,37 @@ class RepeatedCompositeFieldContainer(BaseContainer):
     super(RepeatedCompositeFieldContainer, self).__init__(message_listener)
     self._message_descriptor = message_descriptor
 
-  def add(self):
-    new_element = self._message_descriptor._concrete_class()
+  def add(self, **kwargs):
+    """Adds a new element at the end of the list and returns it. Keyword
+    arguments may be used to initialize the element.
+    """
+    new_element = self._message_descriptor._concrete_class(**kwargs)
     new_element._SetListener(self._message_listener)
     self._values.append(new_element)
     if not self._message_listener.dirty:
       self._message_listener.Modified()
     return new_element
 
-  def MergeFrom(self, other):
-    """Appends the contents of another repeated field of the same type to this
-    one, copying each individual message.
+  def extend(self, elem_seq):
+    """Extends by appending the given sequence of elements of the same type
+    as this one, copying each individual message.
     """
     message_class = self._message_descriptor._concrete_class
     listener = self._message_listener
     values = self._values
-    for message in other._values:
+    for message in elem_seq:
       new_element = message_class()
       new_element._SetListener(listener)
       new_element.MergeFrom(message)
       values.append(new_element)
     listener.Modified()
 
+  def MergeFrom(self, other):
+    """Appends the contents of another repeated field of the same type to this
+    one, copying each individual message.
+    """
+    self.extend(other._values)
+
   def __getslice__(self, start, stop):
     """Retrieves the subset of items from between the specified indices."""
     return self._values[start:stop]
diff --git a/python/google/protobuf/internal/cpp_message.py b/python/google/protobuf/internal/cpp_message.py
new file mode 100755
index 00000000..3f426502
--- /dev/null
+++ b/python/google/protobuf/internal/cpp_message.py
@@ -0,0 +1,616 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# 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.
+
+"""Contains helper functions used to create protocol message classes from
+Descriptor objects at runtime backed by the protocol buffer C++ API.
+"""
+
+__author__ = 'petar@google.com (Petar Petrov)'
+
+import operator
+from google.protobuf.internal import _net_proto2___python
+from google.protobuf import message
+
+
+_LABEL_REPEATED = _net_proto2___python.LABEL_REPEATED
+_LABEL_OPTIONAL = _net_proto2___python.LABEL_OPTIONAL
+_CPPTYPE_MESSAGE = _net_proto2___python.CPPTYPE_MESSAGE
+_TYPE_MESSAGE = _net_proto2___python.TYPE_MESSAGE
+
+
+def GetDescriptorPool():
+  """Creates a new DescriptorPool C++ object."""
+  return _net_proto2___python.NewCDescriptorPool()
+
+
+_pool = GetDescriptorPool()
+
+
+def GetFieldDescriptor(full_field_name):
+  """Searches for a field descriptor given a full field name."""
+  return _pool.FindFieldByName(full_field_name)
+
+
+def BuildFile(content):
+  """Registers a new proto file in the underlying C++ descriptor pool."""
+  _net_proto2___python.BuildFile(content)
+
+
+def GetExtensionDescriptor(full_extension_name):
+  """Searches for extension descriptor given a full field name."""
+  return _pool.FindExtensionByName(full_extension_name)
+
+
+def NewCMessage(full_message_name):
+  """Creates a new C++ protocol message by its name."""
+  return _net_proto2___python.NewCMessage(full_message_name)
+
+
+def ScalarProperty(cdescriptor):
+  """Returns a scalar property for the given descriptor."""
+
+  def Getter(self):
+    return self._cmsg.GetScalar(cdescriptor)
+
+  def Setter(self, value):
+    self._cmsg.SetScalar(cdescriptor, value)
+
+  return property(Getter, Setter)
+
+
+def CompositeProperty(cdescriptor, message_type):
+  """Returns a Python property the given composite field."""
+
+  def Getter(self):
+    sub_message = self._composite_fields.get(cdescriptor.name, None)
+    if sub_message is None:
+      cmessage = self._cmsg.NewSubMessage(cdescriptor)
+      sub_message = message_type._concrete_class(__cmessage=cmessage)
+      self._composite_fields[cdescriptor.name] = sub_message
+    return sub_message
+
+  return property(Getter)
+
+
+class RepeatedScalarContainer(object):
+  """Container for repeated scalar fields."""
+
+  __slots__ = ['_message', '_cfield_descriptor', '_cmsg']
+
+  def __init__(self, msg, cfield_descriptor):
+    self._message = msg
+    self._cmsg = msg._cmsg
+    self._cfield_descriptor = cfield_descriptor
+
+  def append(self, value):
+    self._cmsg.AddRepeatedScalar(
+        self._cfield_descriptor, value)
+
+  def extend(self, sequence):
+    for element in sequence:
+      self.append(element)
+
+  def insert(self, key, value):
+    values = self[slice(None, None, None)]
+    values.insert(key, value)
+    self._cmsg.AssignRepeatedScalar(self._cfield_descriptor, values)
+
+  def remove(self, value):
+    values = self[slice(None, None, None)]
+    values.remove(value)
+    self._cmsg.AssignRepeatedScalar(self._cfield_descriptor, values)
+
+  def __setitem__(self, key, value):
+    values = self[slice(None, None, None)]
+    values[key] = value
+    self._cmsg.AssignRepeatedScalar(self._cfield_descriptor, values)
+
+  def __getitem__(self, key):
+    return self._cmsg.GetRepeatedScalar(self._cfield_descriptor, key)
+
+  def __delitem__(self, key):
+    self._cmsg.DeleteRepeatedField(self._cfield_descriptor, key)
+
+  def __len__(self):
+    return len(self[slice(None, None, None)])
+
+  def __eq__(self, other):
+    if self is other:
+      return True
+    if not operator.isSequenceType(other):
+      raise TypeError(
+          'Can only compare repeated scalar fields against sequences.')
+    # We are presumably comparing against some other sequence type.
+    return other == self[slice(None, None, None)]
+
+  def __ne__(self, other):
+    return not self == other
+
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
+  def sort(self, sort_function=cmp):
+    values = self[slice(None, None, None)]
+    values.sort(sort_function)
+    self._cmsg.AssignRepeatedScalar(self._cfield_descriptor, values)
+
+
+def RepeatedScalarProperty(cdescriptor):
+  """Returns a Python property the given repeated scalar field."""
+
+  def Getter(self):
+    container = self._composite_fields.get(cdescriptor.name, None)
+    if container is None:
+      container = RepeatedScalarContainer(self, cdescriptor)
+      self._composite_fields[cdescriptor.name] = container
+    return container
+
+  def Setter(self, new_value):
+    raise AttributeError('Assignment not allowed to repeated field '
+                         '"%s" in protocol message object.' % cdescriptor.name)
+
+  doc = 'Magic attribute generated for "%s" proto field.' % cdescriptor.name
+  return property(Getter, Setter, doc=doc)
+
+
+class RepeatedCompositeContainer(object):
+  """Container for repeated composite fields."""
+
+  __slots__ = ['_message', '_subclass', '_cfield_descriptor', '_cmsg']
+
+  def __init__(self, msg, cfield_descriptor, subclass):
+    self._message = msg
+    self._cmsg = msg._cmsg
+    self._subclass = subclass
+    self._cfield_descriptor = cfield_descriptor
+
+  def add(self, **kwargs):
+    cmessage = self._cmsg.AddMessage(self._cfield_descriptor)
+    return self._subclass(__cmessage=cmessage, __owner=self._message, **kwargs)
+
+  def extend(self, elem_seq):
+    """Extends by appending the given sequence of elements of the same type
+    as this one, copying each individual message.
+    """
+    for message in elem_seq:
+      self.add().MergeFrom(message)
+
+  def MergeFrom(self, other):
+    for message in other[:]:
+      self.add().MergeFrom(message)
+
+  def __getitem__(self, key):
+    cmessages = self._cmsg.GetRepeatedMessage(
+        self._cfield_descriptor, key)
+    subclass = self._subclass
+    if not isinstance(cmessages, list):
+      return subclass(__cmessage=cmessages, __owner=self._message)
+
+    return [subclass(__cmessage=m, __owner=self._message) for m in cmessages]
+
+  def __delitem__(self, key):
+    self._cmsg.DeleteRepeatedField(
+        self._cfield_descriptor, key)
+
+  def __len__(self):
+    return self._cmsg.FieldLength(self._cfield_descriptor)
+
+  def __eq__(self, other):
+    """Compares the current instance with another one."""
+    if self is other:
+      return True
+    if not isinstance(other, self.__class__):
+      raise TypeError('Can only compare repeated composite fields against '
+                      'other repeated composite fields.')
+    messages = self[slice(None, None, None)]
+    other_messages = other[slice(None, None, None)]
+    return messages == other_messages
+
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
+  def sort(self, sort_function=cmp):
+    messages = []
+    for index in range(len(self)):
+      # messages[i][0] is where the i-th element of the new array has to come
+      # from.
+      # messages[i][1] is where the i-th element of the old array has to go.
+      messages.append([index, 0, self[index]])
+    messages.sort(lambda x,y: sort_function(x[2], y[2]))
+
+    # Remember which position each elements has to move to.
+    for i in range(len(messages)):
+      messages[messages[i][0]][1] = i
+
+    # Apply the transposition.
+    for i in range(len(messages)):
+      from_position = messages[i][0]
+      if i == from_position:
+        continue
+      self._cmsg.SwapRepeatedFieldElements(
+          self._cfield_descriptor, i, from_position)
+      messages[messages[i][1]][0] = from_position
+
+
+def RepeatedCompositeProperty(cdescriptor, message_type):
+  """Returns a Python property for the given repeated composite field."""
+
+  def Getter(self):
+    container = self._composite_fields.get(cdescriptor.name, None)
+    if container is None:
+      container = RepeatedCompositeContainer(
+          self, cdescriptor, message_type._concrete_class)
+      self._composite_fields[cdescriptor.name] = container
+    return container
+
+  def Setter(self, new_value):
+    raise AttributeError('Assignment not allowed to repeated field '
+                         '"%s" in protocol message object.' % cdescriptor.name)
+
+  doc = 'Magic attribute generated for "%s" proto field.' % cdescriptor.name
+  return property(Getter, Setter, doc=doc)
+
+
+class ExtensionDict(object):
+  """Extension dictionary added to each protocol message."""
+
+  def __init__(self, msg):
+    self._message = msg
+    self._cmsg = msg._cmsg
+    self._values = {}
+
+  def __setitem__(self, extension, value):
+    from google.protobuf import descriptor
+    if not isinstance(extension, descriptor.FieldDescriptor):
+      raise KeyError('Bad extension %r.' % (extension,))
+    cdescriptor = extension._cdescriptor
+    if (cdescriptor.label != _LABEL_OPTIONAL or
+        cdescriptor.cpp_type == _CPPTYPE_MESSAGE):
+      raise TypeError('Extension %r is repeated and/or a composite type.' % (
+          extension.full_name,))
+    self._cmsg.SetScalar(cdescriptor, value)
+    self._values[extension] = value
+
+  def __getitem__(self, extension):
+    from google.protobuf import descriptor
+    if not isinstance(extension, descriptor.FieldDescriptor):
+      raise KeyError('Bad extension %r.' % (extension,))
+
+    cdescriptor = extension._cdescriptor
+    if (cdescriptor.label != _LABEL_REPEATED and
+        cdescriptor.cpp_type != _CPPTYPE_MESSAGE):
+      return self._cmsg.GetScalar(cdescriptor)
+
+    ext = self._values.get(extension, None)
+    if ext is not None:
+      return ext
+
+    ext = self._CreateNewHandle(extension)
+    self._values[extension] = ext
+    return ext
+
+  def ClearExtension(self, extension):
+    from google.protobuf import descriptor
+    if not isinstance(extension, descriptor.FieldDescriptor):
+      raise KeyError('Bad extension %r.' % (extension,))
+    self._cmsg.ClearFieldByDescriptor(extension._cdescriptor)
+    if extension in self._values:
+      del self._values[extension]
+
+  def HasExtension(self, extension):
+    from google.protobuf import descriptor
+    if not isinstance(extension, descriptor.FieldDescriptor):
+      raise KeyError('Bad extension %r.' % (extension,))
+    return self._cmsg.HasFieldByDescriptor(extension._cdescriptor)
+
+  def _FindExtensionByName(self, name):
+    """Tries to find a known extension with the specified name.
+
+    Args:
+      name: Extension full name.
+
+    Returns:
+      Extension field descriptor.
+    """
+    return self._message._extensions_by_name.get(name, None)
+
+  def _CreateNewHandle(self, extension):
+    cdescriptor = extension._cdescriptor
+    if (cdescriptor.label != _LABEL_REPEATED and
+        cdescriptor.cpp_type == _CPPTYPE_MESSAGE):
+      cmessage = self._cmsg.NewSubMessage(cdescriptor)
+      return extension.message_type._concrete_class(__cmessage=cmessage)
+
+    if cdescriptor.label == _LABEL_REPEATED:
+      if cdescriptor.cpp_type == _CPPTYPE_MESSAGE:
+        return RepeatedCompositeContainer(
+            self._message, cdescriptor, extension.message_type._concrete_class)
+      else:
+        return RepeatedScalarContainer(self._message, cdescriptor)
+    # This shouldn't happen!
+    assert False
+    return None
+
+
+def NewMessage(message_descriptor, dictionary):
+  """Creates a new protocol message *class*."""
+  _AddClassAttributesForNestedExtensions(message_descriptor, dictionary)
+  _AddEnumValues(message_descriptor, dictionary)
+  _AddDescriptors(message_descriptor, dictionary)
+
+
+def InitMessage(message_descriptor, cls):
+  """Constructs a new message instance (called before instance's __init__)."""
+  cls._extensions_by_name = {}
+  _AddInitMethod(message_descriptor, cls)
+  _AddMessageMethods(message_descriptor, cls)
+  _AddPropertiesForExtensions(message_descriptor, cls)
+
+
+def _AddDescriptors(message_descriptor, dictionary):
+  """Sets up a new protocol message class dictionary.
+
+  Args:
+    message_descriptor: A Descriptor instance describing this message type.
+    dictionary: Class dictionary to which we'll add a '__slots__' entry.
+  """
+  dictionary['__descriptors'] = {}
+  for field in message_descriptor.fields:
+    dictionary['__descriptors'][field.name] = GetFieldDescriptor(
+        field.full_name)
+
+  dictionary['__slots__'] = list(dictionary['__descriptors'].iterkeys()) + [
+      '_cmsg', '_owner', '_composite_fields', 'Extensions']
+
+
+def _AddEnumValues(message_descriptor, dictionary):
+  """Sets class-level attributes for all enum fields defined in this message.
+
+  Args:
+    message_descriptor: Descriptor object for this message type.
+    dictionary: Class dictionary that should be populated.
+  """
+  for enum_type in message_descriptor.enum_types:
+    for enum_value in enum_type.values:
+      dictionary[enum_value.name] = enum_value.number
+
+
+def _AddClassAttributesForNestedExtensions(message_descriptor, dictionary):
+  """Adds class attributes for the nested extensions."""
+  extension_dict = message_descriptor.extensions_by_name
+  for extension_name, extension_field in extension_dict.iteritems():
+    assert extension_name not in dictionary
+    dictionary[extension_name] = extension_field
+
+
+def _AddInitMethod(message_descriptor, cls):
+  """Adds an __init__ method to cls."""
+
+  # Create and attach message field properties to the message class.
+  # This can be done just once per message class, since property setters and
+  # getters are passed the message instance.
+  # This makes message instantiation extremely fast, and at the same time it
+  # doesn't require the creation of property objects for each message instance,
+  # which saves a lot of memory.
+  for field in message_descriptor.fields:
+    field_cdescriptor = cls.__descriptors[field.name]
+    if field.label == _LABEL_REPEATED:
+      if field.cpp_type == _CPPTYPE_MESSAGE:
+        value = RepeatedCompositeProperty(field_cdescriptor, field.message_type)
+      else:
+        value = RepeatedScalarProperty(field_cdescriptor)
+    elif field.cpp_type == _CPPTYPE_MESSAGE:
+      value = CompositeProperty(field_cdescriptor, field.message_type)
+    else:
+      value = ScalarProperty(field_cdescriptor)
+    setattr(cls, field.name, value)
+
+    # Attach a constant with the field number.
+    constant_name = field.name.upper() + '_FIELD_NUMBER'
+    setattr(cls, constant_name, field.number)
+
+  def Init(self, **kwargs):
+    """Message constructor."""
+    cmessage = kwargs.pop('__cmessage', None)
+    if cmessage is None:
+      self._cmsg = NewCMessage(message_descriptor.full_name)
+    else:
+      self._cmsg = cmessage
+
+    # Keep a reference to the owner, as the owner keeps a reference to the
+    # underlying protocol buffer message.
+    owner = kwargs.pop('__owner', None)
+    if owner is not None:
+      self._owner = owner
+
+    self.Extensions = ExtensionDict(self)
+    self._composite_fields = {}
+
+    for field_name, field_value in kwargs.iteritems():
+      field_cdescriptor = self.__descriptors.get(field_name, None)
+      if field_cdescriptor is None:
+        raise ValueError('Protocol message has no "%s" field.' % field_name)
+      if field_cdescriptor.label == _LABEL_REPEATED:
+        if field_cdescriptor.cpp_type == _CPPTYPE_MESSAGE:
+          for val in field_value:
+            getattr(self, field_name).add().MergeFrom(val)
+        else:
+          getattr(self, field_name).extend(field_value)
+      elif field_cdescriptor.cpp_type == _CPPTYPE_MESSAGE:
+        getattr(self, field_name).MergeFrom(field_value)
+      else:
+        setattr(self, field_name, field_value)
+
+  Init.__module__ = None
+  Init.__doc__ = None
+  cls.__init__ = Init
+
+
+def _IsMessageSetExtension(field):
+  """Checks if a field is a message set extension."""
+  return (field.is_extension and
+          field.containing_type.has_options and
+          field.containing_type.GetOptions().message_set_wire_format and
+          field.type == _TYPE_MESSAGE and
+          field.message_type == field.extension_scope and
+          field.label == _LABEL_OPTIONAL)
+
+
+def _AddMessageMethods(message_descriptor, cls):
+  """Adds the methods to a protocol message class."""
+  if message_descriptor.is_extendable:
+
+    def ClearExtension(self, extension):
+      self.Extensions.ClearExtension(extension)
+
+    def HasExtension(self, extension):
+      return self.Extensions.HasExtension(extension)
+
+  def HasField(self, field_name):
+    return self._cmsg.HasField(field_name)
+
+  def ClearField(self, field_name):
+    if field_name in self._composite_fields:
+      del self._composite_fields[field_name]
+    self._cmsg.ClearField(field_name)
+
+  def Clear(self):
+    return self._cmsg.Clear()
+
+  def IsInitialized(self, errors=None):
+    if self._cmsg.IsInitialized():
+      return True
+    if errors is not None:
+      errors.extend(self.FindInitializationErrors());
+    return False
+
+  def SerializeToString(self):
+    if not self.IsInitialized():
+      raise message.EncodeError(
+          'Message is missing required fields: ' +
+          ','.join(self.FindInitializationErrors()))
+    return self._cmsg.SerializeToString()
+
+  def SerializePartialToString(self):
+    return self._cmsg.SerializePartialToString()
+
+  def ParseFromString(self, serialized):
+    self.Clear()
+    self.MergeFromString(serialized)
+
+  def MergeFromString(self, serialized):
+    byte_size = self._cmsg.MergeFromString(serialized)
+    if byte_size < 0:
+      raise message.DecodeError('Unable to merge from string.')
+    return byte_size
+
+  def MergeFrom(self, msg):
+    if not isinstance(msg, cls):
+      raise TypeError(
+          "Parameter to MergeFrom() must be instance of same class.")
+    self._cmsg.MergeFrom(msg._cmsg)
+
+  def CopyFrom(self, msg):
+    self._cmsg.CopyFrom(msg._cmsg)
+
+  def ByteSize(self):
+    return self._cmsg.ByteSize()
+
+  def SetInParent(self):
+    return self._cmsg.SetInParent()
+
+  def ListFields(self):
+    all_fields = []
+    field_list = self._cmsg.ListFields()
+    fields_by_name = cls.DESCRIPTOR.fields_by_name
+    for is_extension, field_name in field_list:
+      if is_extension:
+        extension = cls._extensions_by_name[field_name]
+        all_fields.append((extension, self.Extensions[extension]))
+      else:
+        field_descriptor = fields_by_name[field_name]
+        all_fields.append(
+            (field_descriptor, getattr(self, field_name)))
+    all_fields.sort(key=lambda item: item[0].number)
+    return all_fields
+
+  def FindInitializationErrors(self):
+    return self._cmsg.FindInitializationErrors()
+
+  def __str__(self):
+    return self._cmsg.DebugString()
+
+  def __eq__(self, other):
+    if self is other:
+      return True
+    if not isinstance(other, self.__class__):
+      return False
+    return self.ListFields() == other.ListFields()
+
+  def __ne__(self, other):
+    return not self == other
+
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
+  def __unicode__(self):
+    return text_format.MessageToString(self, as_utf8=True).decode('utf-8')
+
+  # Attach the local methods to the message class.
+  for key, value in locals().copy().iteritems():
+    if key not in ('key', 'value', '__builtins__', '__name__', '__doc__'):
+      setattr(cls, key, value)
+
+  # Static methods:
+
+  def RegisterExtension(extension_handle):
+    extension_handle.containing_type = cls.DESCRIPTOR
+    cls._extensions_by_name[extension_handle.full_name] = extension_handle
+
+    if _IsMessageSetExtension(extension_handle):
+      # MessageSet extension.  Also register under type name.
+      cls._extensions_by_name[
+          extension_handle.message_type.full_name] = extension_handle
+  cls.RegisterExtension = staticmethod(RegisterExtension)
+
+  def FromString(string):
+    msg = cls()
+    msg.MergeFromString(string)
+    return msg
+  cls.FromString = staticmethod(FromString)
+
+
+
+def _AddPropertiesForExtensions(message_descriptor, cls):
+  """Adds properties for all fields in this protocol message type."""
+  extension_dict = message_descriptor.extensions_by_name
+  for extension_name, extension_field in extension_dict.iteritems():
+    constant_name = extension_name.upper() + '_FIELD_NUMBER'
+    setattr(cls, constant_name, extension_field.number)
diff --git a/python/google/protobuf/internal/decoder.py b/python/google/protobuf/internal/decoder.py
index 461a30c0..55f746f5 100755
--- a/python/google/protobuf/internal/decoder.py
+++ b/python/google/protobuf/internal/decoder.py
@@ -86,6 +86,13 @@ from google.protobuf.internal import wire_format
 from google.protobuf import message
 
 
+# This will overflow and thus become IEEE-754 "infinity".  We would use
+# "float('inf')" but it doesn't work on Windows pre-Python-2.6.
+_POS_INF = 1e10000
+_NEG_INF = -_POS_INF
+_NAN = _POS_INF * 0
+
+
 # This is not for optimization, but rather to avoid conflicts with local
 # variables named "message".
 _DecodeError = message.DecodeError
@@ -269,6 +276,72 @@ def _StructPackDecoder(wire_type, format):
   return _SimpleDecoder(wire_type, InnerDecode)
 
 
+def _FloatDecoder():
+  """Returns a decoder for a float field.
+
+  This code works around a bug in struct.unpack for non-finite 32-bit
+  floating-point values.
+  """
+
+  local_unpack = struct.unpack
+
+  def InnerDecode(buffer, pos):
+    # We expect a 32-bit value in little-endian byte order.  Bit 1 is the sign
+    # bit, bits 2-9 represent the exponent, and bits 10-32 are the significand.
+    new_pos = pos + 4
+    float_bytes = buffer[pos:new_pos]
+
+    # If this value has all its exponent bits set, then it's non-finite.
+    # In Python 2.4, struct.unpack will convert it to a finite 64-bit value.
+    # To avoid that, we parse it specially.
+    if ((float_bytes[3] in '\x7F\xFF')
+        and (float_bytes[2] >= '\x80')):
+      # If at least one significand bit is set...
+      if float_bytes[0:3] != '\x00\x00\x80':
+        return (_NAN, new_pos)
+      # If sign bit is set...
+      if float_bytes[3] == '\xFF':
+        return (_NEG_INF, new_pos)
+      return (_POS_INF, new_pos)
+
+    # Note that we expect someone up-stack to catch struct.error and convert
+    # it to _DecodeError -- this way we don't have to set up exception-
+    # handling blocks every time we parse one value.
+    result = local_unpack('<f', float_bytes)[0]
+    return (result, new_pos)
+  return _SimpleDecoder(wire_format.WIRETYPE_FIXED32, InnerDecode)
+
+
+def _DoubleDecoder():
+  """Returns a decoder for a double field.
+
+  This code works around a bug in struct.unpack for not-a-number.
+  """
+
+  local_unpack = struct.unpack
+
+  def InnerDecode(buffer, pos):
+    # We expect a 64-bit value in little-endian byte order.  Bit 1 is the sign
+    # bit, bits 2-12 represent the exponent, and bits 13-64 are the significand.
+    new_pos = pos + 8
+    double_bytes = buffer[pos:new_pos]
+
+    # If this value has all its exponent bits set and at least one significand
+    # bit set, it's not a number.  In Python 2.4, struct.unpack will treat it
+    # as inf or -inf.  To avoid that, we treat it specially.
+    if ((double_bytes[7] in '\x7F\xFF')
+        and (double_bytes[6] >= '\xF0')
+        and (double_bytes[0:7] != '\x00\x00\x00\x00\x00\x00\xF0')):
+      return (_NAN, new_pos)
+
+    # Note that we expect someone up-stack to catch struct.error and convert
+    # it to _DecodeError -- this way we don't have to set up exception-
+    # handling blocks every time we parse one value.
+    result = local_unpack('<d', double_bytes)[0]
+    return (result, new_pos)
+  return _SimpleDecoder(wire_format.WIRETYPE_FIXED64, InnerDecode)
+
+
 # --------------------------------------------------------------------
 
 
@@ -294,8 +367,8 @@ Fixed32Decoder  = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<I')
 Fixed64Decoder  = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<Q')
 SFixed32Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<i')
 SFixed64Decoder = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<q')
-FloatDecoder    = _StructPackDecoder(wire_format.WIRETYPE_FIXED32, '<f')
-DoubleDecoder   = _StructPackDecoder(wire_format.WIRETYPE_FIXED64, '<d')
+FloatDecoder = _FloatDecoder()
+DoubleDecoder = _DoubleDecoder()
 
 BoolDecoder = _ModifiedDecoder(
     wire_format.WIRETYPE_VARINT, _DecodeVarint, bool)
diff --git a/python/google/protobuf/internal/encoder.py b/python/google/protobuf/internal/encoder.py
index aa05d5b3..777975e8 100755
--- a/python/google/protobuf/internal/encoder.py
+++ b/python/google/protobuf/internal/encoder.py
@@ -70,6 +70,12 @@ import struct
 from google.protobuf.internal import wire_format
 
 
+# This will overflow and thus become IEEE-754 "infinity".  We would use
+# "float('inf')" but it doesn't work on Windows pre-Python-2.6.
+_POS_INF = 1e10000
+_NEG_INF = -_POS_INF
+
+
 def _VarintSize(value):
   """Compute the size of a varint value."""
   if value <= 0x7f: return 1
@@ -502,6 +508,83 @@ def _StructPackEncoder(wire_type, format):
   return SpecificEncoder
 
 
+def _FloatingPointEncoder(wire_type, format):
+  """Return a constructor for an encoder for float fields.
+
+  This is like StructPackEncoder, but catches errors that may be due to
+  passing non-finite floating-point values to struct.pack, and makes a
+  second attempt to encode those values.
+
+  Args:
+      wire_type:  The field's wire type, for encoding tags.
+      format:  The format string to pass to struct.pack().
+  """
+
+  value_size = struct.calcsize(format)
+  if value_size == 4:
+    def EncodeNonFiniteOrRaise(write, value):
+      # Remember that the serialized form uses little-endian byte order.
+      if value == _POS_INF:
+        write('\x00\x00\x80\x7F')
+      elif value == _NEG_INF:
+        write('\x00\x00\x80\xFF')
+      elif value != value:           # NaN
+        write('\x00\x00\xC0\x7F')
+      else:
+        raise
+  elif value_size == 8:
+    def EncodeNonFiniteOrRaise(write, value):
+      if value == _POS_INF:
+        write('\x00\x00\x00\x00\x00\x00\xF0\x7F')
+      elif value == _NEG_INF:
+        write('\x00\x00\x00\x00\x00\x00\xF0\xFF')
+      elif value != value:                         # NaN
+        write('\x00\x00\x00\x00\x00\x00\xF8\x7F')
+      else:
+        raise
+  else:
+    raise ValueError('Can\'t encode floating-point values that are '
+                     '%d bytes long (only 4 or 8)' % value_size)
+
+  def SpecificEncoder(field_number, is_repeated, is_packed):
+    local_struct_pack = struct.pack
+    if is_packed:
+      tag_bytes = TagBytes(field_number, wire_format.WIRETYPE_LENGTH_DELIMITED)
+      local_EncodeVarint = _EncodeVarint
+      def EncodePackedField(write, value):
+        write(tag_bytes)
+        local_EncodeVarint(write, len(value) * value_size)
+        for element in value:
+          # This try/except block is going to be faster than any code that
+          # we could write to check whether element is finite.
+          try:
+            write(local_struct_pack(format, element))
+          except SystemError:
+            EncodeNonFiniteOrRaise(write, element)
+      return EncodePackedField
+    elif is_repeated:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeRepeatedField(write, value):
+        for element in value:
+          write(tag_bytes)
+          try:
+            write(local_struct_pack(format, element))
+          except SystemError:
+            EncodeNonFiniteOrRaise(write, element)
+      return EncodeRepeatedField
+    else:
+      tag_bytes = TagBytes(field_number, wire_type)
+      def EncodeField(write, value):
+        write(tag_bytes)
+        try:
+          write(local_struct_pack(format, value))
+        except SystemError:
+          EncodeNonFiniteOrRaise(write, value)
+      return EncodeField
+
+  return SpecificEncoder
+
+
 # ====================================================================
 # Here we declare an encoder constructor for each field type.  These work
 # very similarly to sizer constructors, described earlier.
@@ -525,8 +608,8 @@ Fixed32Encoder  = _StructPackEncoder(wire_format.WIRETYPE_FIXED32, '<I')
 Fixed64Encoder  = _StructPackEncoder(wire_format.WIRETYPE_FIXED64, '<Q')
 SFixed32Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED32, '<i')
 SFixed64Encoder = _StructPackEncoder(wire_format.WIRETYPE_FIXED64, '<q')
-FloatEncoder    = _StructPackEncoder(wire_format.WIRETYPE_FIXED32, '<f')
-DoubleEncoder   = _StructPackEncoder(wire_format.WIRETYPE_FIXED64, '<d')
+FloatEncoder    = _FloatingPointEncoder(wire_format.WIRETYPE_FIXED32, '<f')
+DoubleEncoder   = _FloatingPointEncoder(wire_format.WIRETYPE_FIXED64, '<d')
 
 
 def BoolEncoder(field_number, is_repeated, is_packed):
diff --git a/python/google/protobuf/internal/generator_test.py b/python/google/protobuf/internal/generator_test.py
index 78360b53..e4387c85 100755
--- a/python/google/protobuf/internal/generator_test.py
+++ b/python/google/protobuf/internal/generator_test.py
@@ -42,11 +42,12 @@ further ensures that we can use Python protocol message objects as we expect.
 __author__ = 'robinson@google.com (Will Robinson)'
 
 import unittest
+from google.protobuf import unittest_custom_options_pb2
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_mset_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf import unittest_no_generic_services_pb2
-
+from google.protobuf import service
 
 MAX_EXTENSION = 536870912
 
@@ -140,6 +141,13 @@ class GeneratorTest(unittest.TestCase):
     proto = unittest_mset_pb2.TestMessageSet()
     self.assertTrue(proto.DESCRIPTOR.GetOptions().message_set_wire_format)
 
+  def testMessageWithCustomOptions(self):
+    proto = unittest_custom_options_pb2.TestMessageWithCustomOptions()
+    enum_options = proto.DESCRIPTOR.enum_types_by_name['AnEnum'].GetOptions()
+    self.assertTrue(enum_options is not None)
+    # TODO(gps): We really should test for the presense of the enum_opt1
+    # extension and for its value to be set to -789.
+
   def testNestedTypes(self):
     self.assertEquals(
         set(unittest_pb2.TestAllTypes.DESCRIPTOR.nested_types),
@@ -208,12 +216,27 @@ class GeneratorTest(unittest.TestCase):
     self.assertFalse(unittest_pb2.DESCRIPTOR.serialized_pb is None)
 
   def testNoGenericServices(self):
-    # unittest_no_generic_services.proto should contain defs for everything
-    # except services.
     self.assertTrue(hasattr(unittest_no_generic_services_pb2, "TestMessage"))
     self.assertTrue(hasattr(unittest_no_generic_services_pb2, "FOO"))
     self.assertTrue(hasattr(unittest_no_generic_services_pb2, "test_extension"))
-    self.assertFalse(hasattr(unittest_no_generic_services_pb2, "TestService"))
+
+    # Make sure unittest_no_generic_services_pb2 has no services subclassing
+    # Proto2 Service class.
+    if hasattr(unittest_no_generic_services_pb2, "TestService"):
+      self.assertFalse(issubclass(unittest_no_generic_services_pb2.TestService,
+                                  service.Service))
+
+  def testMessageTypesByName(self):
+    file_type = unittest_pb2.DESCRIPTOR
+    self.assertEqual(
+        unittest_pb2._TESTALLTYPES,
+        file_type.message_types_by_name[unittest_pb2._TESTALLTYPES.name])
+
+    # Nested messages shouldn't be included in the message_types_by_name
+    # dictionary (like in the C++ API).
+    self.assertFalse(
+        unittest_pb2._TESTALLTYPES_NESTEDMESSAGE.name in
+        file_type.message_types_by_name)
 
 
 if __name__ == '__main__':
diff --git a/python/google/protobuf/internal/message_test.py b/python/google/protobuf/internal/message_test.py
index 73a9a3a3..65174373 100755
--- a/python/google/protobuf/internal/message_test.py
+++ b/python/google/protobuf/internal/message_test.py
@@ -43,11 +43,25 @@ abstract interface.
 
 __author__ = 'gps@google.com (Gregory P. Smith)'
 
+import copy
+import math
 import unittest
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_pb2
 from google.protobuf.internal import test_util
 
+# Python pre-2.6 does not have isinf() or isnan() functions, so we have
+# to provide our own.
+def isnan(val):
+  # NaN is never equal to itself.
+  return val != val
+def isinf(val):
+  # Infinity times zero equals NaN.
+  return not isnan(val) and isnan(val * 0)
+def IsPosInf(val):
+  return isinf(val) and (val > 0)
+def IsNegInf(val):
+  return isinf(val) and (val < 0)
 
 class MessageTest(unittest.TestCase):
 
@@ -57,6 +71,8 @@ class MessageTest(unittest.TestCase):
     golden_message.ParseFromString(golden_data)
     test_util.ExpectAllFieldsSet(self, golden_message)
     self.assertTrue(golden_message.SerializeToString() == golden_data)
+    golden_copy = copy.deepcopy(golden_message)
+    self.assertTrue(golden_copy.SerializeToString() == golden_data)
 
   def testGoldenExtensions(self):
     golden_data = test_util.GoldenFile('golden_message').read()
@@ -66,6 +82,8 @@ class MessageTest(unittest.TestCase):
     test_util.SetAllExtensions(all_set)
     self.assertEquals(all_set, golden_message)
     self.assertTrue(golden_message.SerializeToString() == golden_data)
+    golden_copy = copy.deepcopy(golden_message)
+    self.assertTrue(golden_copy.SerializeToString() == golden_data)
 
   def testGoldenPackedMessage(self):
     golden_data = test_util.GoldenFile('golden_packed_fields_message').read()
@@ -75,6 +93,8 @@ class MessageTest(unittest.TestCase):
     test_util.SetAllPackedFields(all_set)
     self.assertEquals(all_set, golden_message)
     self.assertTrue(all_set.SerializeToString() == golden_data)
+    golden_copy = copy.deepcopy(golden_message)
+    self.assertTrue(golden_copy.SerializeToString() == golden_data)
 
   def testGoldenPackedExtensions(self):
     golden_data = test_util.GoldenFile('golden_packed_fields_message').read()
@@ -84,6 +104,240 @@ class MessageTest(unittest.TestCase):
     test_util.SetAllPackedExtensions(all_set)
     self.assertEquals(all_set, golden_message)
     self.assertTrue(all_set.SerializeToString() == golden_data)
+    golden_copy = copy.deepcopy(golden_message)
+    self.assertTrue(golden_copy.SerializeToString() == golden_data)
+
+  def testPositiveInfinity(self):
+    golden_data = ('\x5D\x00\x00\x80\x7F'
+                   '\x61\x00\x00\x00\x00\x00\x00\xF0\x7F'
+                   '\xCD\x02\x00\x00\x80\x7F'
+                   '\xD1\x02\x00\x00\x00\x00\x00\x00\xF0\x7F')
+    golden_message = unittest_pb2.TestAllTypes()
+    golden_message.ParseFromString(golden_data)
+    self.assertTrue(IsPosInf(golden_message.optional_float))
+    self.assertTrue(IsPosInf(golden_message.optional_double))
+    self.assertTrue(IsPosInf(golden_message.repeated_float[0]))
+    self.assertTrue(IsPosInf(golden_message.repeated_double[0]))
+    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+  def testNegativeInfinity(self):
+    golden_data = ('\x5D\x00\x00\x80\xFF'
+                   '\x61\x00\x00\x00\x00\x00\x00\xF0\xFF'
+                   '\xCD\x02\x00\x00\x80\xFF'
+                   '\xD1\x02\x00\x00\x00\x00\x00\x00\xF0\xFF')
+    golden_message = unittest_pb2.TestAllTypes()
+    golden_message.ParseFromString(golden_data)
+    self.assertTrue(IsNegInf(golden_message.optional_float))
+    self.assertTrue(IsNegInf(golden_message.optional_double))
+    self.assertTrue(IsNegInf(golden_message.repeated_float[0]))
+    self.assertTrue(IsNegInf(golden_message.repeated_double[0]))
+    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+  def testNotANumber(self):
+    golden_data = ('\x5D\x00\x00\xC0\x7F'
+                   '\x61\x00\x00\x00\x00\x00\x00\xF8\x7F'
+                   '\xCD\x02\x00\x00\xC0\x7F'
+                   '\xD1\x02\x00\x00\x00\x00\x00\x00\xF8\x7F')
+    golden_message = unittest_pb2.TestAllTypes()
+    golden_message.ParseFromString(golden_data)
+    self.assertTrue(isnan(golden_message.optional_float))
+    self.assertTrue(isnan(golden_message.optional_double))
+    self.assertTrue(isnan(golden_message.repeated_float[0]))
+    self.assertTrue(isnan(golden_message.repeated_double[0]))
+    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+  def testPositiveInfinityPacked(self):
+    golden_data = ('\xA2\x06\x04\x00\x00\x80\x7F'
+                   '\xAA\x06\x08\x00\x00\x00\x00\x00\x00\xF0\x7F')
+    golden_message = unittest_pb2.TestPackedTypes()
+    golden_message.ParseFromString(golden_data)
+    self.assertTrue(IsPosInf(golden_message.packed_float[0]))
+    self.assertTrue(IsPosInf(golden_message.packed_double[0]))
+    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+  def testNegativeInfinityPacked(self):
+    golden_data = ('\xA2\x06\x04\x00\x00\x80\xFF'
+                   '\xAA\x06\x08\x00\x00\x00\x00\x00\x00\xF0\xFF')
+    golden_message = unittest_pb2.TestPackedTypes()
+    golden_message.ParseFromString(golden_data)
+    self.assertTrue(IsNegInf(golden_message.packed_float[0]))
+    self.assertTrue(IsNegInf(golden_message.packed_double[0]))
+    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+  def testNotANumberPacked(self):
+    golden_data = ('\xA2\x06\x04\x00\x00\xC0\x7F'
+                   '\xAA\x06\x08\x00\x00\x00\x00\x00\x00\xF8\x7F')
+    golden_message = unittest_pb2.TestPackedTypes()
+    golden_message.ParseFromString(golden_data)
+    self.assertTrue(isnan(golden_message.packed_float[0]))
+    self.assertTrue(isnan(golden_message.packed_double[0]))
+    self.assertTrue(golden_message.SerializeToString() == golden_data)
+
+  def testExtremeFloatValues(self):
+    message = unittest_pb2.TestAllTypes()
+
+    # Most positive exponent, no significand bits set.
+    kMostPosExponentNoSigBits = math.pow(2, 127)
+    message.optional_float = kMostPosExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == kMostPosExponentNoSigBits)
+
+    # Most positive exponent, one significand bit set.
+    kMostPosExponentOneSigBit = 1.5 * math.pow(2, 127)
+    message.optional_float = kMostPosExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == kMostPosExponentOneSigBit)
+
+    # Repeat last two cases with values of same magnitude, but negative.
+    message.optional_float = -kMostPosExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == -kMostPosExponentNoSigBits)
+
+    message.optional_float = -kMostPosExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == -kMostPosExponentOneSigBit)
+
+    # Most negative exponent, no significand bits set.
+    kMostNegExponentNoSigBits = math.pow(2, -127)
+    message.optional_float = kMostNegExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == kMostNegExponentNoSigBits)
+
+    # Most negative exponent, one significand bit set.
+    kMostNegExponentOneSigBit = 1.5 * math.pow(2, -127)
+    message.optional_float = kMostNegExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == kMostNegExponentOneSigBit)
+
+    # Repeat last two cases with values of the same magnitude, but negative.
+    message.optional_float = -kMostNegExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == -kMostNegExponentNoSigBits)
+
+    message.optional_float = -kMostNegExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_float == -kMostNegExponentOneSigBit)
+
+  def testExtremeFloatValues(self):
+    message = unittest_pb2.TestAllTypes()
+
+    # Most positive exponent, no significand bits set.
+    kMostPosExponentNoSigBits = math.pow(2, 1023)
+    message.optional_double = kMostPosExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == kMostPosExponentNoSigBits)
+
+    # Most positive exponent, one significand bit set.
+    kMostPosExponentOneSigBit = 1.5 * math.pow(2, 1023)
+    message.optional_double = kMostPosExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == kMostPosExponentOneSigBit)
+
+    # Repeat last two cases with values of same magnitude, but negative.
+    message.optional_double = -kMostPosExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == -kMostPosExponentNoSigBits)
+
+    message.optional_double = -kMostPosExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == -kMostPosExponentOneSigBit)
+
+    # Most negative exponent, no significand bits set.
+    kMostNegExponentNoSigBits = math.pow(2, -1023)
+    message.optional_double = kMostNegExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == kMostNegExponentNoSigBits)
+
+    # Most negative exponent, one significand bit set.
+    kMostNegExponentOneSigBit = 1.5 * math.pow(2, -1023)
+    message.optional_double = kMostNegExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == kMostNegExponentOneSigBit)
+
+    # Repeat last two cases with values of the same magnitude, but negative.
+    message.optional_double = -kMostNegExponentNoSigBits
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == -kMostNegExponentNoSigBits)
+
+    message.optional_double = -kMostNegExponentOneSigBit
+    message.ParseFromString(message.SerializeToString())
+    self.assertTrue(message.optional_double == -kMostNegExponentOneSigBit)
+
+  def testSortingRepeatedScalarFieldsDefaultComparator(self):
+    """Check some different types with the default comparator."""
+    message = unittest_pb2.TestAllTypes()
+
+    # TODO(mattp): would testing more scalar types strengthen test?
+    message.repeated_int32.append(1)
+    message.repeated_int32.append(3)
+    message.repeated_int32.append(2)
+    message.repeated_int32.sort()
+    self.assertEqual(message.repeated_int32[0], 1)
+    self.assertEqual(message.repeated_int32[1], 2)
+    self.assertEqual(message.repeated_int32[2], 3)
+
+    message.repeated_float.append(1.1)
+    message.repeated_float.append(1.3)
+    message.repeated_float.append(1.2)
+    message.repeated_float.sort()
+    self.assertAlmostEqual(message.repeated_float[0], 1.1)
+    self.assertAlmostEqual(message.repeated_float[1], 1.2)
+    self.assertAlmostEqual(message.repeated_float[2], 1.3)
+
+    message.repeated_string.append('a')
+    message.repeated_string.append('c')
+    message.repeated_string.append('b')
+    message.repeated_string.sort()
+    self.assertEqual(message.repeated_string[0], 'a')
+    self.assertEqual(message.repeated_string[1], 'b')
+    self.assertEqual(message.repeated_string[2], 'c')
+
+    message.repeated_bytes.append('a')
+    message.repeated_bytes.append('c')
+    message.repeated_bytes.append('b')
+    message.repeated_bytes.sort()
+    self.assertEqual(message.repeated_bytes[0], 'a')
+    self.assertEqual(message.repeated_bytes[1], 'b')
+    self.assertEqual(message.repeated_bytes[2], 'c')
+
+  def testSortingRepeatedScalarFieldsCustomComparator(self):
+    """Check some different types with custom comparator."""
+    message = unittest_pb2.TestAllTypes()
+
+    message.repeated_int32.append(-3)
+    message.repeated_int32.append(-2)
+    message.repeated_int32.append(-1)
+    message.repeated_int32.sort(lambda x,y: cmp(abs(x), abs(y)))
+    self.assertEqual(message.repeated_int32[0], -1)
+    self.assertEqual(message.repeated_int32[1], -2)
+    self.assertEqual(message.repeated_int32[2], -3)
+
+    message.repeated_string.append('aaa')
+    message.repeated_string.append('bb')
+    message.repeated_string.append('c')
+    message.repeated_string.sort(lambda x,y: cmp(len(x), len(y)))
+    self.assertEqual(message.repeated_string[0], 'c')
+    self.assertEqual(message.repeated_string[1], 'bb')
+    self.assertEqual(message.repeated_string[2], 'aaa')
+
+  def testSortingRepeatedCompositeFieldsCustomComparator(self):
+    """Check passing a custom comparator to sort a repeated composite field."""
+    message = unittest_pb2.TestAllTypes()
+
+    message.repeated_nested_message.add().bb = 1
+    message.repeated_nested_message.add().bb = 3
+    message.repeated_nested_message.add().bb = 2
+    message.repeated_nested_message.add().bb = 6
+    message.repeated_nested_message.add().bb = 5
+    message.repeated_nested_message.add().bb = 4
+    message.repeated_nested_message.sort(lambda x,y: cmp(x.bb, y.bb))
+    self.assertEqual(message.repeated_nested_message[0].bb, 1)
+    self.assertEqual(message.repeated_nested_message[1].bb, 2)
+    self.assertEqual(message.repeated_nested_message[2].bb, 3)
+    self.assertEqual(message.repeated_nested_message[3].bb, 4)
+    self.assertEqual(message.repeated_nested_message[4].bb, 5)
+    self.assertEqual(message.repeated_nested_message[5].bb, 6)
+
 
 if __name__ == '__main__':
   unittest.main()
diff --git a/python/google/protobuf/internal/python_message.py b/python/google/protobuf/internal/python_message.py
new file mode 100755
index 00000000..66fca918
--- /dev/null
+++ b/python/google/protobuf/internal/python_message.py
@@ -0,0 +1,1098 @@
+# Protocol Buffers - Google's data interchange format
+# Copyright 2008 Google Inc.  All rights reserved.
+# http://code.google.com/p/protobuf/
+#
+# 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.
+
+# This code is meant to work on Python 2.4 and above only.
+#
+# TODO(robinson): Helpers for verbose, common checks like seeing if a
+# descriptor's cpp_type is CPPTYPE_MESSAGE.
+
+"""Contains a metaclass and helper functions used to create
+protocol message classes from Descriptor objects at runtime.
+
+Recall that a metaclass is the "type" of a class.
+(A class is to a metaclass what an instance is to a class.)
+
+In this case, we use the GeneratedProtocolMessageType metaclass
+to inject all the useful functionality into the classes
+output by the protocol compiler at compile-time.
+
+The upshot of all this is that the real implementation
+details for ALL pure-Python protocol buffers are *here in
+this file*.
+"""
+
+__author__ = 'robinson@google.com (Will Robinson)'
+
+try:
+  from cStringIO import StringIO
+except ImportError:
+  from StringIO import StringIO
+import struct
+import weakref
+
+# We use "as" to avoid name collisions with variables.
+from google.protobuf.internal import containers
+from google.protobuf.internal import decoder
+from google.protobuf.internal import encoder
+from google.protobuf.internal import message_listener as message_listener_mod
+from google.protobuf.internal import type_checkers
+from google.protobuf.internal import wire_format
+from google.protobuf import descriptor as descriptor_mod
+from google.protobuf import message as message_mod
+from google.protobuf import text_format
+
+_FieldDescriptor = descriptor_mod.FieldDescriptor
+
+
+def NewMessage(descriptor, dictionary):
+  _AddClassAttributesForNestedExtensions(descriptor, dictionary)
+  _AddSlots(descriptor, dictionary)
+
+
+def InitMessage(descriptor, cls):
+  cls._decoders_by_tag = {}
+  cls._extensions_by_name = {}
+  cls._extensions_by_number = {}
+  if (descriptor.has_options and
+      descriptor.GetOptions().message_set_wire_format):
+    cls._decoders_by_tag[decoder.MESSAGE_SET_ITEM_TAG] = (
+        decoder.MessageSetItemDecoder(cls._extensions_by_number))
+
+  # Attach stuff to each FieldDescriptor for quick lookup later on.
+  for field in descriptor.fields:
+    _AttachFieldHelpers(cls, field)
+
+  _AddEnumValues(descriptor, cls)
+  _AddInitMethod(descriptor, cls)
+  _AddPropertiesForFields(descriptor, cls)
+  _AddPropertiesForExtensions(descriptor, cls)
+  _AddStaticMethods(cls)
+  _AddMessageMethods(descriptor, cls)
+  _AddPrivateHelperMethods(cls)
+
+
+# Stateless helpers for GeneratedProtocolMessageType below.
+# Outside clients should not access these directly.
+#
+# I opted not to make any of these methods on the metaclass, to make it more
+# clear that I'm not really using any state there and to keep clients from
+# thinking that they have direct access to these construction helpers.
+
+
+def _PropertyName(proto_field_name):
+  """Returns the name of the public property attribute which
+  clients can use to get and (in some cases) set the value
+  of a protocol message field.
+
+  Args:
+    proto_field_name: The protocol message field name, exactly
+      as it appears (or would appear) in a .proto file.
+  """
+  # TODO(robinson): Escape Python keywords (e.g., yield), and test this support.
+  # nnorwitz makes my day by writing:
+  # """
+  # FYI.  See the keyword module in the stdlib. This could be as simple as:
+  #
+  # if keyword.iskeyword(proto_field_name):
+  #   return proto_field_name + "_"
+  # return proto_field_name
+  # """
+  # Kenton says:  The above is a BAD IDEA.  People rely on being able to use
+  #   getattr() and setattr() to reflectively manipulate field values.  If we
+  #   rename the properties, then every such user has to also make sure to apply
+  #   the same transformation.  Note that currently if you name a field "yield",
+  #   you can still access it just fine using getattr/setattr -- it's not even
+  #   that cumbersome to do so.
+  # TODO(kenton):  Remove this method entirely if/when everyone agrees with my
+  #   position.
+  return proto_field_name
+
+
+def _VerifyExtensionHandle(message, extension_handle):
+  """Verify that the given extension handle is valid."""
+
+  if not isinstance(extension_handle, _FieldDescriptor):
+    raise KeyError('HasExtension() expects an extension handle, got: %s' %
+                   extension_handle)
+
+  if not extension_handle.is_extension:
+    raise KeyError('"%s" is not an extension.' % extension_handle.full_name)
+
+  if extension_handle.containing_type is not message.DESCRIPTOR:
+    raise KeyError('Extension "%s" extends message type "%s", but this '
+                   'message is of type "%s".' %
+                   (extension_handle.full_name,
+                    extension_handle.containing_type.full_name,
+                    message.DESCRIPTOR.full_name))
+
+
+def _AddSlots(message_descriptor, dictionary):
+  """Adds a __slots__ entry to dictionary, containing the names of all valid
+  attributes for this message type.
+
+  Args:
+    message_descriptor: A Descriptor instance describing this message type.
+    dictionary: Class dictionary to which we'll add a '__slots__' entry.
+  """
+  dictionary['__slots__'] = ['_cached_byte_size',
+                             '_cached_byte_size_dirty',
+                             '_fields',
+                             '_is_present_in_parent',
+                             '_listener',
+                             '_listener_for_children',
+                             '__weakref__']
+
+
+def _IsMessageSetExtension(field):
+  return (field.is_extension and
+          field.containing_type.has_options and
+          field.containing_type.GetOptions().message_set_wire_format and
+          field.type == _FieldDescriptor.TYPE_MESSAGE and
+          field.message_type == field.extension_scope and
+          field.label == _FieldDescriptor.LABEL_OPTIONAL)
+
+
+def _AttachFieldHelpers(cls, field_descriptor):
+  is_repeated = (field_descriptor.label == _FieldDescriptor.LABEL_REPEATED)
+  is_packed = (field_descriptor.has_options and
+               field_descriptor.GetOptions().packed)
+
+  if _IsMessageSetExtension(field_descriptor):
+    field_encoder = encoder.MessageSetItemEncoder(field_descriptor.number)
+    sizer = encoder.MessageSetItemSizer(field_descriptor.number)
+  else:
+    field_encoder = type_checkers.TYPE_TO_ENCODER[field_descriptor.type](
+        field_descriptor.number, is_repeated, is_packed)
+    sizer = type_checkers.TYPE_TO_SIZER[field_descriptor.type](
+        field_descriptor.number, is_repeated, is_packed)
+
+  field_descriptor._encoder = field_encoder
+  field_descriptor._sizer = sizer
+  field_descriptor._default_constructor = _DefaultValueConstructorForField(
+      field_descriptor)
+
+  def AddDecoder(wiretype, is_packed):
+    tag_bytes = encoder.TagBytes(field_descriptor.number, wiretype)
+    cls._decoders_by_tag[tag_bytes] = (
+        type_checkers.TYPE_TO_DECODER[field_descriptor.type](
+            field_descriptor.number, is_repeated, is_packed,
+            field_descriptor, field_descriptor._default_constructor))
+
+  AddDecoder(type_checkers.FIELD_TYPE_TO_WIRE_TYPE[field_descriptor.type],
+             False)
+
+  if is_repeated and wire_format.IsTypePackable(field_descriptor.type):
+    # To support wire compatibility of adding packed = true, add a decoder for
+    # packed values regardless of the field's options.
+    AddDecoder(wire_format.WIRETYPE_LENGTH_DELIMITED, True)
+
+
+def _AddClassAttributesForNestedExtensions(descriptor, dictionary):
+  extension_dict = descriptor.extensions_by_name
+  for extension_name, extension_field in extension_dict.iteritems():
+    assert extension_name not in dictionary
+    dictionary[extension_name] = extension_field
+
+
+def _AddEnumValues(descriptor, cls):
+  """Sets class-level attributes for all enum fields defined in this message.
+
+  Args:
+    descriptor: Descriptor object for this message type.
+    cls: Class we're constructing for this message type.
+  """
+  for enum_type in descriptor.enum_types:
+    for enum_value in enum_type.values:
+      setattr(cls, enum_value.name, enum_value.number)
+
+
+def _DefaultValueConstructorForField(field):
+  """Returns a function which returns a default value for a field.
+
+  Args:
+    field: FieldDescriptor object for this field.
+
+  The returned function has one argument:
+    message: Message instance containing this field, or a weakref proxy
+      of same.
+
+  That function in turn returns a default value for this field.  The default
+    value may refer back to |message| via a weak reference.
+  """
+
+  if field.label == _FieldDescriptor.LABEL_REPEATED:
+    if field.default_value != []:
+      raise ValueError('Repeated field default value not empty list: %s' % (
+          field.default_value))
+    if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      # We can't look at _concrete_class yet since it might not have
+      # been set.  (Depends on order in which we initialize the classes).
+      message_type = field.message_type
+      def MakeRepeatedMessageDefault(message):
+        return containers.RepeatedCompositeFieldContainer(
+            message._listener_for_children, field.message_type)
+      return MakeRepeatedMessageDefault
+    else:
+      type_checker = type_checkers.GetTypeChecker(field.cpp_type, field.type)
+      def MakeRepeatedScalarDefault(message):
+        return containers.RepeatedScalarFieldContainer(
+            message._listener_for_children, type_checker)
+      return MakeRepeatedScalarDefault
+
+  if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+    # _concrete_class may not yet be initialized.
+    message_type = field.message_type
+    def MakeSubMessageDefault(message):
+      result = message_type._concrete_class()
+      result._SetListener(message._listener_for_children)
+      return result
+    return MakeSubMessageDefault
+
+  def MakeScalarDefault(message):
+    return field.default_value
+  return MakeScalarDefault
+
+
+def _AddInitMethod(message_descriptor, cls):
+  """Adds an __init__ method to cls."""
+  fields = message_descriptor.fields
+  def init(self, **kwargs):
+    self._cached_byte_size = 0
+    self._cached_byte_size_dirty = len(kwargs) > 0
+    self._fields = {}
+    self._is_present_in_parent = False
+    self._listener = message_listener_mod.NullMessageListener()
+    self._listener_for_children = _Listener(self)
+    for field_name, field_value in kwargs.iteritems():
+      field = _GetFieldByName(message_descriptor, field_name)
+      if field is None:
+        raise TypeError("%s() got an unexpected keyword argument '%s'" %
+                        (message_descriptor.name, field_name))
+      if field.label == _FieldDescriptor.LABEL_REPEATED:
+        copy = field._default_constructor(self)
+        if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:  # Composite
+          for val in field_value:
+            copy.add().MergeFrom(val)
+        else:  # Scalar
+          copy.extend(field_value)
+        self._fields[field] = copy
+      elif field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+        copy = field._default_constructor(self)
+        copy.MergeFrom(field_value)
+        self._fields[field] = copy
+      else:
+        setattr(self, field_name, field_value)
+
+  init.__module__ = None
+  init.__doc__ = None
+  cls.__init__ = init
+
+
+def _GetFieldByName(message_descriptor, field_name):
+  """Returns a field descriptor by field name.
+
+  Args:
+    message_descriptor: A Descriptor describing all fields in message.
+    field_name: The name of the field to retrieve.
+  Returns:
+    The field descriptor associated with the field name.
+  """
+  try:
+    return message_descriptor.fields_by_name[field_name]
+  except KeyError:
+    raise ValueError('Protocol message has no "%s" field.' % field_name)
+
+
+def _AddPropertiesForFields(descriptor, cls):
+  """Adds properties for all fields in this protocol message type."""
+  for field in descriptor.fields:
+    _AddPropertiesForField(field, cls)
+
+  if descriptor.is_extendable:
+    # _ExtensionDict is just an adaptor with no state so we allocate a new one
+    # every time it is accessed.
+    cls.Extensions = property(lambda self: _ExtensionDict(self))
+
+
+def _AddPropertiesForField(field, cls):
+  """Adds a public property for a protocol message field.
+  Clients can use this property to get and (in the case
+  of non-repeated scalar fields) directly set the value
+  of a protocol message field.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  # Catch it if we add other types that we should
+  # handle specially here.
+  assert _FieldDescriptor.MAX_CPPTYPE == 10
+
+  constant_name = field.name.upper() + "_FIELD_NUMBER"
+  setattr(cls, constant_name, field.number)
+
+  if field.label == _FieldDescriptor.LABEL_REPEATED:
+    _AddPropertiesForRepeatedField(field, cls)
+  elif field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+    _AddPropertiesForNonRepeatedCompositeField(field, cls)
+  else:
+    _AddPropertiesForNonRepeatedScalarField(field, cls)
+
+
+def _AddPropertiesForRepeatedField(field, cls):
+  """Adds a public property for a "repeated" protocol message field.  Clients
+  can use this property to get the value of the field, which will be either a
+  _RepeatedScalarFieldContainer or _RepeatedCompositeFieldContainer (see
+  below).
+
+  Note that when clients add values to these containers, we perform
+  type-checking in the case of repeated scalar fields, and we also set any
+  necessary "has" bits as a side-effect.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  proto_field_name = field.name
+  property_name = _PropertyName(proto_field_name)
+
+  def getter(self):
+    field_value = self._fields.get(field)
+    if field_value is None:
+      # Construct a new object to represent this field.
+      field_value = field._default_constructor(self)
+
+      # Atomically check if another thread has preempted us and, if not, swap
+      # in the new object we just created.  If someone has preempted us, we
+      # take that object and discard ours.
+      # WARNING:  We are relying on setdefault() being atomic.  This is true
+      #   in CPython but we haven't investigated others.  This warning appears
+      #   in several other locations in this file.
+      field_value = self._fields.setdefault(field, field_value)
+    return field_value
+  getter.__module__ = None
+  getter.__doc__ = 'Getter for %s.' % proto_field_name
+
+  # We define a setter just so we can throw an exception with a more
+  # helpful error message.
+  def setter(self, new_value):
+    raise AttributeError('Assignment not allowed to repeated field '
+                         '"%s" in protocol message object.' % proto_field_name)
+
+  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
+  setattr(cls, property_name, property(getter, setter, doc=doc))
+
+
+def _AddPropertiesForNonRepeatedScalarField(field, cls):
+  """Adds a public property for a nonrepeated, scalar protocol message field.
+  Clients can use this property to get and directly set the value of the field.
+  Note that when the client sets the value of a field by using this property,
+  all necessary "has" bits are set as a side-effect, and we also perform
+  type-checking.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  proto_field_name = field.name
+  property_name = _PropertyName(proto_field_name)
+  type_checker = type_checkers.GetTypeChecker(field.cpp_type, field.type)
+  default_value = field.default_value
+  valid_values = set()
+
+  def getter(self):
+    return self._fields.get(field, default_value)
+  getter.__module__ = None
+  getter.__doc__ = 'Getter for %s.' % proto_field_name
+  def setter(self, new_value):
+    type_checker.CheckValue(new_value)
+    self._fields[field] = new_value
+    # Check _cached_byte_size_dirty inline to improve performance, since scalar
+    # setters are called frequently.
+    if not self._cached_byte_size_dirty:
+      self._Modified()
+
+  setter.__module__ = None
+  setter.__doc__ = 'Setter for %s.' % proto_field_name
+
+  # Add a property to encapsulate the getter/setter.
+  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
+  setattr(cls, property_name, property(getter, setter, doc=doc))
+
+
+def _AddPropertiesForNonRepeatedCompositeField(field, cls):
+  """Adds a public property for a nonrepeated, composite protocol message field.
+  A composite field is a "group" or "message" field.
+
+  Clients can use this property to get the value of the field, but cannot
+  assign to the property directly.
+
+  Args:
+    field: A FieldDescriptor for this field.
+    cls: The class we're constructing.
+  """
+  # TODO(robinson): Remove duplication with similar method
+  # for non-repeated scalars.
+  proto_field_name = field.name
+  property_name = _PropertyName(proto_field_name)
+  message_type = field.message_type
+
+  def getter(self):
+    field_value = self._fields.get(field)
+    if field_value is None:
+      # Construct a new object to represent this field.
+      field_value = message_type._concrete_class()
+      field_value._SetListener(self._listener_for_children)
+
+      # Atomically check if another thread has preempted us and, if not, swap
+      # in the new object we just created.  If someone has preempted us, we
+      # take that object and discard ours.
+      # WARNING:  We are relying on setdefault() being atomic.  This is true
+      #   in CPython but we haven't investigated others.  This warning appears
+      #   in several other locations in this file.
+      field_value = self._fields.setdefault(field, field_value)
+    return field_value
+  getter.__module__ = None
+  getter.__doc__ = 'Getter for %s.' % proto_field_name
+
+  # We define a setter just so we can throw an exception with a more
+  # helpful error message.
+  def setter(self, new_value):
+    raise AttributeError('Assignment not allowed to composite field '
+                         '"%s" in protocol message object.' % proto_field_name)
+
+  # Add a property to encapsulate the getter.
+  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
+  setattr(cls, property_name, property(getter, setter, doc=doc))
+
+
+def _AddPropertiesForExtensions(descriptor, cls):
+  """Adds properties for all fields in this protocol message type."""
+  extension_dict = descriptor.extensions_by_name
+  for extension_name, extension_field in extension_dict.iteritems():
+    constant_name = extension_name.upper() + "_FIELD_NUMBER"
+    setattr(cls, constant_name, extension_field.number)
+
+
+def _AddStaticMethods(cls):
+  # TODO(robinson): This probably needs to be thread-safe(?)
+  def RegisterExtension(extension_handle):
+    extension_handle.containing_type = cls.DESCRIPTOR
+    _AttachFieldHelpers(cls, extension_handle)
+
+    # Try to insert our extension, failing if an extension with the same number
+    # already exists.
+    actual_handle = cls._extensions_by_number.setdefault(
+        extension_handle.number, extension_handle)
+    if actual_handle is not extension_handle:
+      raise AssertionError(
+          'Extensions "%s" and "%s" both try to extend message type "%s" with '
+          'field number %d.' %
+          (extension_handle.full_name, actual_handle.full_name,
+           cls.DESCRIPTOR.full_name, extension_handle.number))
+
+    cls._extensions_by_name[extension_handle.full_name] = extension_handle
+
+    handle = extension_handle  # avoid line wrapping
+    if _IsMessageSetExtension(handle):
+      # MessageSet extension.  Also register under type name.
+      cls._extensions_by_name[
+          extension_handle.message_type.full_name] = extension_handle
+
+  cls.RegisterExtension = staticmethod(RegisterExtension)
+
+  def FromString(s):
+    message = cls()
+    message.MergeFromString(s)
+    return message
+  cls.FromString = staticmethod(FromString)
+
+
+def _IsPresent(item):
+  """Given a (FieldDescriptor, value) tuple from _fields, return true if the
+  value should be included in the list returned by ListFields()."""
+
+  if item[0].label == _FieldDescriptor.LABEL_REPEATED:
+    return bool(item[1])
+  elif item[0].cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+    return item[1]._is_present_in_parent
+  else:
+    return True
+
+
+def _AddListFieldsMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def ListFields(self):
+    all_fields = [item for item in self._fields.iteritems() if _IsPresent(item)]
+    all_fields.sort(key = lambda item: item[0].number)
+    return all_fields
+
+  cls.ListFields = ListFields
+
+
+def _AddHasFieldMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  singular_fields = {}
+  for field in message_descriptor.fields:
+    if field.label != _FieldDescriptor.LABEL_REPEATED:
+      singular_fields[field.name] = field
+
+  def HasField(self, field_name):
+    try:
+      field = singular_fields[field_name]
+    except KeyError:
+      raise ValueError(
+          'Protocol message has no singular "%s" field.' % field_name)
+
+    if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      value = self._fields.get(field)
+      return value is not None and value._is_present_in_parent
+    else:
+      return field in self._fields
+  cls.HasField = HasField
+
+
+def _AddClearFieldMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def ClearField(self, field_name):
+    try:
+      field = message_descriptor.fields_by_name[field_name]
+    except KeyError:
+      raise ValueError('Protocol message has no "%s" field.' % field_name)
+
+    if field in self._fields:
+      # Note:  If the field is a sub-message, its listener will still point
+      #   at us.  That's fine, because the worst than can happen is that it
+      #   will call _Modified() and invalidate our byte size.  Big deal.
+      del self._fields[field]
+
+    # Always call _Modified() -- even if nothing was changed, this is
+    # a mutating method, and thus calling it should cause the field to become
+    # present in the parent message.
+    self._Modified()
+
+  cls.ClearField = ClearField
+
+
+def _AddClearExtensionMethod(cls):
+  """Helper for _AddMessageMethods()."""
+  def ClearExtension(self, extension_handle):
+    _VerifyExtensionHandle(self, extension_handle)
+
+    # Similar to ClearField(), above.
+    if extension_handle in self._fields:
+      del self._fields[extension_handle]
+    self._Modified()
+  cls.ClearExtension = ClearExtension
+
+
+def _AddClearMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def Clear(self):
+    # Clear fields.
+    self._fields = {}
+    self._Modified()
+  cls.Clear = Clear
+
+
+def _AddHasExtensionMethod(cls):
+  """Helper for _AddMessageMethods()."""
+  def HasExtension(self, extension_handle):
+    _VerifyExtensionHandle(self, extension_handle)
+    if extension_handle.label == _FieldDescriptor.LABEL_REPEATED:
+      raise KeyError('"%s" is repeated.' % extension_handle.full_name)
+
+    if extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      value = self._fields.get(extension_handle)
+      return value is not None and value._is_present_in_parent
+    else:
+      return extension_handle in self._fields
+  cls.HasExtension = HasExtension
+
+
+def _AddEqualsMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def __eq__(self, other):
+    if (not isinstance(other, message_mod.Message) or
+        other.DESCRIPTOR != self.DESCRIPTOR):
+      return False
+
+    if self is other:
+      return True
+
+    return self.ListFields() == other.ListFields()
+
+  cls.__eq__ = __eq__
+
+
+def _AddStrMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def __str__(self):
+    return text_format.MessageToString(self)
+  cls.__str__ = __str__
+
+
+def _AddUnicodeMethod(unused_message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def __unicode__(self):
+    return text_format.MessageToString(self, as_utf8=True).decode('utf-8')
+  cls.__unicode__ = __unicode__
+
+
+def _AddSetListenerMethod(cls):
+  """Helper for _AddMessageMethods()."""
+  def SetListener(self, listener):
+    if listener is None:
+      self._listener = message_listener_mod.NullMessageListener()
+    else:
+      self._listener = listener
+  cls._SetListener = SetListener
+
+
+def _BytesForNonRepeatedElement(value, field_number, field_type):
+  """Returns the number of bytes needed to serialize a non-repeated element.
+  The returned byte count includes space for tag information and any
+  other additional space associated with serializing value.
+
+  Args:
+    value: Value we're serializing.
+    field_number: Field number of this value.  (Since the field number
+      is stored as part of a varint-encoded tag, this has an impact
+      on the total bytes required to serialize the value).
+    field_type: The type of the field.  One of the TYPE_* constants
+      within FieldDescriptor.
+  """
+  try:
+    fn = type_checkers.TYPE_TO_BYTE_SIZE_FN[field_type]
+    return fn(field_number, value)
+  except KeyError:
+    raise message_mod.EncodeError('Unrecognized field type: %d' % field_type)
+
+
+def _AddByteSizeMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def ByteSize(self):
+    if not self._cached_byte_size_dirty:
+      return self._cached_byte_size
+
+    size = 0
+    for field_descriptor, field_value in self.ListFields():
+      size += field_descriptor._sizer(field_value)
+
+    self._cached_byte_size = size
+    self._cached_byte_size_dirty = False
+    self._listener_for_children.dirty = False
+    return size
+
+  cls.ByteSize = ByteSize
+
+
+def _AddSerializeToStringMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def SerializeToString(self):
+    # Check if the message has all of its required fields set.
+    errors = []
+    if not self.IsInitialized():
+      raise message_mod.EncodeError(
+          'Message is missing required fields: ' +
+          ','.join(self.FindInitializationErrors()))
+    return self.SerializePartialToString()
+  cls.SerializeToString = SerializeToString
+
+
+def _AddSerializePartialToStringMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+
+  def SerializePartialToString(self):
+    out = StringIO()
+    self._InternalSerialize(out.write)
+    return out.getvalue()
+  cls.SerializePartialToString = SerializePartialToString
+
+  def InternalSerialize(self, write_bytes):
+    for field_descriptor, field_value in self.ListFields():
+      field_descriptor._encoder(write_bytes, field_value)
+  cls._InternalSerialize = InternalSerialize
+
+
+def _AddMergeFromStringMethod(message_descriptor, cls):
+  """Helper for _AddMessageMethods()."""
+  def MergeFromString(self, serialized):
+    length = len(serialized)
+    try:
+      if self._InternalParse(serialized, 0, length) != length:
+        # The only reason _InternalParse would return early is if it
+        # encountered an end-group tag.
+        raise message_mod.DecodeError('Unexpected end-group tag.')
+    except IndexError:
+      raise message_mod.DecodeError('Truncated message.')
+    except struct.error, e:
+      raise message_mod.DecodeError(e)
+    return length   # Return this for legacy reasons.
+  cls.MergeFromString = MergeFromString
+
+  local_ReadTag = decoder.ReadTag
+  local_SkipField = decoder.SkipField
+  decoders_by_tag = cls._decoders_by_tag
+
+  def InternalParse(self, buffer, pos, end):
+    self._Modified()
+    field_dict = self._fields
+    while pos != end:
+      (tag_bytes, new_pos) = local_ReadTag(buffer, pos)
+      field_decoder = decoders_by_tag.get(tag_bytes)
+      if field_decoder is None:
+        new_pos = local_SkipField(buffer, new_pos, end, tag_bytes)
+        if new_pos == -1:
+          return pos
+        pos = new_pos
+      else:
+        pos = field_decoder(buffer, new_pos, end, self, field_dict)
+    return pos
+  cls._InternalParse = InternalParse
+
+
+def _AddIsInitializedMethod(message_descriptor, cls):
+  """Adds the IsInitialized and FindInitializationError methods to the
+  protocol message class."""
+
+  required_fields = [field for field in message_descriptor.fields
+                           if field.label == _FieldDescriptor.LABEL_REQUIRED]
+
+  def IsInitialized(self, errors=None):
+    """Checks if all required fields of a message are set.
+
+    Args:
+      errors:  A list which, if provided, will be populated with the field
+               paths of all missing required fields.
+
+    Returns:
+      True iff the specified message has all required fields set.
+    """
+
+    # Performance is critical so we avoid HasField() and ListFields().
+
+    for field in required_fields:
+      if (field not in self._fields or
+          (field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE and
+           not self._fields[field]._is_present_in_parent)):
+        if errors is not None:
+          errors.extend(self.FindInitializationErrors())
+        return False
+
+    for field, value in self._fields.iteritems():
+      if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+        if field.label == _FieldDescriptor.LABEL_REPEATED:
+          for element in value:
+            if not element.IsInitialized():
+              if errors is not None:
+                errors.extend(self.FindInitializationErrors())
+              return False
+        elif value._is_present_in_parent and not value.IsInitialized():
+          if errors is not None:
+            errors.extend(self.FindInitializationErrors())
+          return False
+
+    return True
+
+  cls.IsInitialized = IsInitialized
+
+  def FindInitializationErrors(self):
+    """Finds required fields which are not initialized.
+
+    Returns:
+      A list of strings.  Each string is a path to an uninitialized field from
+      the top-level message, e.g. "foo.bar[5].baz".
+    """
+
+    errors = []  # simplify things
+
+    for field in required_fields:
+      if not self.HasField(field.name):
+        errors.append(field.name)
+
+    for field, value in self.ListFields():
+      if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+        if field.is_extension:
+          name = "(%s)" % field.full_name
+        else:
+          name = field.name
+
+        if field.label == _FieldDescriptor.LABEL_REPEATED:
+          for i in xrange(len(value)):
+            element = value[i]
+            prefix = "%s[%d]." % (name, i)
+            sub_errors = element.FindInitializationErrors()
+            errors += [ prefix + error for error in sub_errors ]
+        else:
+          prefix = name + "."
+          sub_errors = value.FindInitializationErrors()
+          errors += [ prefix + error for error in sub_errors ]
+
+    return errors
+
+  cls.FindInitializationErrors = FindInitializationErrors
+
+
+def _AddMergeFromMethod(cls):
+  LABEL_REPEATED = _FieldDescriptor.LABEL_REPEATED
+  CPPTYPE_MESSAGE = _FieldDescriptor.CPPTYPE_MESSAGE
+
+  def MergeFrom(self, msg):
+    if not isinstance(msg, cls):
+      raise TypeError(
+          "Parameter to MergeFrom() must be instance of same class.")
+
+    assert msg is not self
+    self._Modified()
+
+    fields = self._fields
+
+    for field, value in msg._fields.iteritems():
+      if field.label == LABEL_REPEATED:
+        field_value = fields.get(field)
+        if field_value is None:
+          # Construct a new object to represent this field.
+          field_value = field._default_constructor(self)
+          fields[field] = field_value
+        field_value.MergeFrom(value)
+      elif field.cpp_type == CPPTYPE_MESSAGE:
+        if value._is_present_in_parent:
+          field_value = fields.get(field)
+          if field_value is None:
+            # Construct a new object to represent this field.
+            field_value = field._default_constructor(self)
+            fields[field] = field_value
+          field_value.MergeFrom(value)
+      else:
+        self._fields[field] = value
+  cls.MergeFrom = MergeFrom
+
+
+def _AddMessageMethods(message_descriptor, cls):
+  """Adds implementations of all Message methods to cls."""
+  _AddListFieldsMethod(message_descriptor, cls)
+  _AddHasFieldMethod(message_descriptor, cls)
+  _AddClearFieldMethod(message_descriptor, cls)
+  if message_descriptor.is_extendable:
+    _AddClearExtensionMethod(cls)
+    _AddHasExtensionMethod(cls)
+  _AddClearMethod(message_descriptor, cls)
+  _AddEqualsMethod(message_descriptor, cls)
+  _AddStrMethod(message_descriptor, cls)
+  _AddUnicodeMethod(message_descriptor, cls)
+  _AddSetListenerMethod(cls)
+  _AddByteSizeMethod(message_descriptor, cls)
+  _AddSerializeToStringMethod(message_descriptor, cls)
+  _AddSerializePartialToStringMethod(message_descriptor, cls)
+  _AddMergeFromStringMethod(message_descriptor, cls)
+  _AddIsInitializedMethod(message_descriptor, cls)
+  _AddMergeFromMethod(cls)
+
+
+def _AddPrivateHelperMethods(cls):
+  """Adds implementation of private helper methods to cls."""
+
+  def Modified(self):
+    """Sets the _cached_byte_size_dirty bit to true,
+    and propagates this to our listener iff this was a state change.
+    """
+
+    # Note:  Some callers check _cached_byte_size_dirty before calling
+    #   _Modified() as an extra optimization.  So, if this method is ever
+    #   changed such that it does stuff even when _cached_byte_size_dirty is
+    #   already true, the callers need to be updated.
+    if not self._cached_byte_size_dirty:
+      self._cached_byte_size_dirty = True
+      self._listener_for_children.dirty = True
+      self._is_present_in_parent = True
+      self._listener.Modified()
+
+  cls._Modified = Modified
+  cls.SetInParent = Modified
+
+
+class _Listener(object):
+
+  """MessageListener implementation that a parent message registers with its
+  child message.
+
+  In order to support semantics like:
+
+    foo.bar.baz.qux = 23
+    assert foo.HasField('bar')
+
+  ...child objects must have back references to their parents.
+  This helper class is at the heart of this support.
+  """
+
+  def __init__(self, parent_message):
+    """Args:
+      parent_message: The message whose _Modified() method we should call when
+        we receive Modified() messages.
+    """
+    # This listener establishes a back reference from a child (contained) object
+    # to its parent (containing) object.  We make this a weak reference to avoid
+    # creating cyclic garbage when the client finishes with the 'parent' object
+    # in the tree.
+    if isinstance(parent_message, weakref.ProxyType):
+      self._parent_message_weakref = parent_message
+    else:
+      self._parent_message_weakref = weakref.proxy(parent_message)
+
+    # As an optimization, we also indicate directly on the listener whether
+    # or not the parent message is dirty.  This way we can avoid traversing
+    # up the tree in the common case.
+    self.dirty = False
+
+  def Modified(self):
+    if self.dirty:
+      return
+    try:
+      # Propagate the signal to our parents iff this is the first field set.
+      self._parent_message_weakref._Modified()
+    except ReferenceError:
+      # We can get here if a client has kept a reference to a child object,
+      # and is now setting a field on it, but the child's parent has been
+      # garbage-collected.  This is not an error.
+      pass
+
+
+# TODO(robinson): Move elsewhere?  This file is getting pretty ridiculous...
+# TODO(robinson): Unify error handling of "unknown extension" crap.
+# TODO(robinson): Support iteritems()-style iteration over all
+# extensions with the "has" bits turned on?
+class _ExtensionDict(object):
+
+  """Dict-like container for supporting an indexable "Extensions"
+  field on proto instances.
+
+  Note that in all cases we expect extension handles to be
+  FieldDescriptors.
+  """
+
+  def __init__(self, extended_message):
+    """extended_message: Message instance for which we are the Extensions dict.
+    """
+
+    self._extended_message = extended_message
+
+  def __getitem__(self, extension_handle):
+    """Returns the current value of the given extension handle."""
+
+    _VerifyExtensionHandle(self._extended_message, extension_handle)
+
+    result = self._extended_message._fields.get(extension_handle)
+    if result is not None:
+      return result
+
+    if extension_handle.label == _FieldDescriptor.LABEL_REPEATED:
+      result = extension_handle._default_constructor(self._extended_message)
+    elif extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
+      result = extension_handle.message_type._concrete_class()
+      try:
+        result._SetListener(self._extended_message._listener_for_children)
+      except ReferenceError:
+        pass
+    else:
+      # Singular scalar -- just return the default without inserting into the
+      # dict.
+      return extension_handle.default_value
+
+    # Atomically check if another thread has preempted us and, if not, swap
+    # in the new object we just created.  If someone has preempted us, we
+    # take that object and discard ours.
+    # WARNING:  We are relying on setdefault() being atomic.  This is true
+    #   in CPython but we haven't investigated others.  This warning appears
+    #   in several other locations in this file.
+    result = self._extended_message._fields.setdefault(
+        extension_handle, result)
+
+    return result
+
+  def __eq__(self, other):
+    if not isinstance(other, self.__class__):
+      return False
+
+    my_fields = self._extended_message.ListFields()
+    other_fields = other._extended_message.ListFields()
+
+    # Get rid of non-extension fields.
+    my_fields    = [ field for field in my_fields    if field.is_extension ]
+    other_fields = [ field for field in other_fields if field.is_extension ]
+
+    return my_fields == other_fields
+
+  def __ne__(self, other):
+    return not self == other
+
+  def __hash__(self):
+    raise TypeError('unhashable object')
+
+  # Note that this is only meaningful for non-repeated, scalar extension
+  # fields.  Note also that we may have to call _Modified() when we do
+  # successfully set a field this way, to set any necssary "has" bits in the
+  # ancestors of the extended message.
+  def __setitem__(self, extension_handle, value):
+    """If extension_handle specifies a non-repeated, scalar extension
+    field, sets the value of that field.
+    """
+
+    _VerifyExtensionHandle(self._extended_message, extension_handle)
+
+    if (extension_handle.label == _FieldDescriptor.LABEL_REPEATED or
+        extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE):
+      raise TypeError(
+          'Cannot assign to extension "%s" because it is a repeated or '
+          'composite type.' % extension_handle.full_name)
+
+    # It's slightly wasteful to lookup the type checker each time,
+    # but we expect this to be a vanishingly uncommon case anyway.
+    type_checker = type_checkers.GetTypeChecker(
+        extension_handle.cpp_type, extension_handle.type)
+    type_checker.CheckValue(value)
+    self._extended_message._fields[extension_handle] = value
+    self._extended_message._Modified()
+
+  def _FindExtensionByName(self, name):
+    """Tries to find a known extension with the specified name.
+
+    Args:
+      name: Extension full name.
+
+    Returns:
+      Extension field descriptor.
+    """
+    return self._extended_message._extensions_by_name.get(name, None)
diff --git a/python/google/protobuf/internal/reflection_test.py b/python/google/protobuf/internal/reflection_test.py
index 54eeebe6..7b9d3398 100755
--- a/python/google/protobuf/internal/reflection_test.py
+++ b/python/google/protobuf/internal/reflection_test.py
@@ -41,8 +41,6 @@ import operator
 import struct
 
 import unittest
-# TODO(robinson): When we split this test in two, only some of these imports
-# will be necessary in each test.
 from google.protobuf import unittest_import_pb2
 from google.protobuf import unittest_mset_pb2
 from google.protobuf import unittest_pb2
@@ -50,6 +48,7 @@ from google.protobuf import descriptor_pb2
 from google.protobuf import descriptor
 from google.protobuf import message
 from google.protobuf import reflection
+from google.protobuf.internal import api_implementation
 from google.protobuf.internal import more_extensions_pb2
 from google.protobuf.internal import more_messages_pb2
 from google.protobuf.internal import wire_format
@@ -104,10 +103,10 @@ class _MiniDecoder(object):
 
 class ReflectionTest(unittest.TestCase):
 
-  def assertIs(self, values, others):
+  def assertListsEqual(self, values, others):
     self.assertEqual(len(values), len(others))
     for i in range(len(values)):
-      self.assertTrue(values[i] is others[i])
+      self.assertEqual(values[i], others[i])
 
   def testScalarConstructor(self):
     # Constructor with only scalar types should succeed.
@@ -201,15 +200,24 @@ class ReflectionTest(unittest.TestCase):
         list(proto.repeated_foreign_message))
 
   def testConstructorTypeError(self):
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, optional_int32="foo")
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, optional_string=1234)
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, optional_nested_message=1234)
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, repeated_int32=1234)
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, repeated_int32=["foo"])
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, repeated_string=1234)
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, repeated_string=[1234])
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, repeated_nested_message=1234)
-    self.assertRaises(TypeError, unittest_pb2.TestAllTypes, repeated_nested_message=[1234])
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, optional_int32="foo")
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, optional_string=1234)
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, optional_nested_message=1234)
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, repeated_int32=1234)
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, repeated_int32=["foo"])
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, repeated_string=1234)
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, repeated_string=[1234])
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, repeated_nested_message=1234)
+    self.assertRaises(
+        TypeError, unittest_pb2.TestAllTypes, repeated_nested_message=[1234])
 
   def testConstructorInvalidatesCachedByteSize(self):
     message = unittest_pb2.TestAllTypes(optional_int32 = 12)
@@ -311,11 +319,14 @@ class ReflectionTest(unittest.TestCase):
       self.assertEqual(0, getattr(composite_field, scalar_field_name))
 
       # Finally, ensure that modifications to the old composite field object
-      # don't have any effect on the parent.
+      # don't have any effect on the parent. Possible only with the pure-python
+      # implementation of the API.
       #
       # (NOTE that when we clear the composite field in the parent, we actually
       # don't recursively clear down the tree.  Instead, we just disconnect the
       # cleared composite from the tree.)
+      if api_implementation.Type() != 'python':
+        return
       self.assertTrue(old_composite_field is not composite_field)
       setattr(old_composite_field, scalar_field_name, new_val)
       self.assertTrue(not composite_field.HasField(scalar_field_name))
@@ -337,6 +348,8 @@ class ReflectionTest(unittest.TestCase):
     nested.bb = 23
 
   def testDisconnectingNestedMessageBeforeSettingField(self):
+    if api_implementation.Type() != 'python':
+      return
     proto = unittest_pb2.TestAllTypes()
     nested = proto.optional_nested_message
     proto.ClearField('optional_nested_message')  # Should disconnect from parent
@@ -526,7 +539,6 @@ class ReflectionTest(unittest.TestCase):
     # proto.nonexistent_field = 23 should fail as well.
     self.assertRaises(AttributeError, setattr, proto, 'nonexistent_field', 23)
 
-  # TODO(robinson): Add type-safety check for enums.
   def testSingleScalarTypeSafety(self):
     proto = unittest_pb2.TestAllTypes()
     self.assertRaises(TypeError, setattr, proto, 'optional_int32', 1.1)
@@ -538,7 +550,9 @@ class ReflectionTest(unittest.TestCase):
     def TestMinAndMaxIntegers(field_name, expected_min, expected_max):
       pb = unittest_pb2.TestAllTypes()
       setattr(pb, field_name, expected_min)
+      self.assertEqual(expected_min, getattr(pb, field_name))
       setattr(pb, field_name, expected_max)
+      self.assertEqual(expected_max, getattr(pb, field_name))
       self.assertRaises(ValueError, setattr, pb, field_name, expected_min - 1)
       self.assertRaises(ValueError, setattr, pb, field_name, expected_max + 1)
 
@@ -546,7 +560,33 @@ class ReflectionTest(unittest.TestCase):
     TestMinAndMaxIntegers('optional_uint32', 0, 0xffffffff)
     TestMinAndMaxIntegers('optional_int64', -(1 << 63), (1 << 63) - 1)
     TestMinAndMaxIntegers('optional_uint64', 0, 0xffffffffffffffff)
-    TestMinAndMaxIntegers('optional_nested_enum', -(1 << 31), (1 << 31) - 1)
+
+    pb = unittest_pb2.TestAllTypes()
+    pb.optional_nested_enum = 1
+    self.assertEqual(1, pb.optional_nested_enum)
+
+    # Invalid enum values.
+    pb.optional_nested_enum = 0
+    self.assertEqual(0, pb.optional_nested_enum)
+
+    bytes_size_before = pb.ByteSize()
+
+    pb.optional_nested_enum = 4
+    self.assertEqual(4, pb.optional_nested_enum)
+
+    pb.optional_nested_enum = 0
+    self.assertEqual(0, pb.optional_nested_enum)
+
+    # Make sure that setting the same enum field doesn't just add unknown
+    # fields (but overwrites them).
+    self.assertEqual(bytes_size_before, pb.ByteSize())
+
+    # Is the invalid value preserved after serialization?
+    serialized = pb.SerializeToString()
+    pb2 = unittest_pb2.TestAllTypes()
+    pb2.ParseFromString(serialized)
+    self.assertEqual(0, pb2.optional_nested_enum)
+    self.assertEqual(pb, pb2)
 
   def testRepeatedScalarTypeSafety(self):
     proto = unittest_pb2.TestAllTypes()
@@ -560,11 +600,19 @@ class ReflectionTest(unittest.TestCase):
     self.assertRaises(IndexError, proto.repeated_int32.__setitem__, 500, 23)
     self.assertRaises(TypeError, proto.repeated_int32.__setitem__, 0, 'abc')
 
+    # Repeated enums tests.
+    #proto.repeated_nested_enum.append(0)
+
   def testSingleScalarGettersAndSetters(self):
     proto = unittest_pb2.TestAllTypes()
     self.assertEqual(0, proto.optional_int32)
     proto.optional_int32 = 1
     self.assertEqual(1, proto.optional_int32)
+
+    proto.optional_uint64 = 0xffffffffffff
+    self.assertEqual(0xffffffffffff, proto.optional_uint64)
+    proto.optional_uint64 = 0xffffffffffffffff
+    self.assertEqual(0xffffffffffffffff, proto.optional_uint64)
     # TODO(robinson): Test all other scalar field types.
 
   def testSingleScalarClearField(self):
@@ -645,11 +693,38 @@ class ReflectionTest(unittest.TestCase):
     del proto.repeated_int32[2:]
     self.assertEqual([5, 35], proto.repeated_int32)
 
+    # Test extending.
+    proto.repeated_int32.extend([3, 13])
+    self.assertEqual([5, 35, 3, 13], proto.repeated_int32)
+
     # Test clearing.
     proto.ClearField('repeated_int32')
     self.assertTrue(not proto.repeated_int32)
     self.assertEqual(0, len(proto.repeated_int32))
 
+    proto.repeated_int32.append(1)
+    self.assertEqual(1, proto.repeated_int32[-1])
+    # Test assignment to a negative index.
+    proto.repeated_int32[-1] = 2
+    self.assertEqual(2, proto.repeated_int32[-1])
+
+    # Test deletion at negative indices.
+    proto.repeated_int32[:] = [0, 1, 2, 3]
+    del proto.repeated_int32[-1]
+    self.assertEqual([0, 1, 2], proto.repeated_int32)
+
+    del proto.repeated_int32[-2]
+    self.assertEqual([0, 2], proto.repeated_int32)
+
+    self.assertRaises(IndexError, proto.repeated_int32.__delitem__, -3)
+    self.assertRaises(IndexError, proto.repeated_int32.__delitem__, 300)
+
+    del proto.repeated_int32[-2:-1]
+    self.assertEqual([2], proto.repeated_int32)
+
+    del proto.repeated_int32[100:10000]
+    self.assertEqual([2], proto.repeated_int32)
+
   def testRepeatedScalarsRemove(self):
     proto = unittest_pb2.TestAllTypes()
 
@@ -687,7 +762,7 @@ class ReflectionTest(unittest.TestCase):
     m1 = proto.repeated_nested_message.add()
     self.assertTrue(proto.repeated_nested_message)
     self.assertEqual(2, len(proto.repeated_nested_message))
-    self.assertIs([m0, m1], proto.repeated_nested_message)
+    self.assertListsEqual([m0, m1], proto.repeated_nested_message)
     self.assertTrue(isinstance(m0, unittest_pb2.TestAllTypes.NestedMessage))
 
     # Test out-of-bounds indices.
@@ -706,32 +781,57 @@ class ReflectionTest(unittest.TestCase):
     m2 = proto.repeated_nested_message.add()
     m3 = proto.repeated_nested_message.add()
     m4 = proto.repeated_nested_message.add()
-    self.assertIs([m1, m2, m3], proto.repeated_nested_message[1:4])
-    self.assertIs([m0, m1, m2, m3, m4], proto.repeated_nested_message[:])
+    self.assertListsEqual(
+        [m1, m2, m3], proto.repeated_nested_message[1:4])
+    self.assertListsEqual(
+        [m0, m1, m2, m3, m4], proto.repeated_nested_message[:])
+    self.assertListsEqual(
+        [m0, m1], proto.repeated_nested_message[:2])
+    self.assertListsEqual(
+        [m2, m3, m4], proto.repeated_nested_message[2:])
+    self.assertEqual(
+        m0, proto.repeated_nested_message[0])
+    self.assertListsEqual(
+        [m0], proto.repeated_nested_message[:1])
 
     # Test that we can use the field as an iterator.
     result = []
     for i in proto.repeated_nested_message:
       result.append(i)
-    self.assertIs([m0, m1, m2, m3, m4], result)
+    self.assertListsEqual([m0, m1, m2, m3, m4], result)
 
     # Test single deletion.
     del proto.repeated_nested_message[2]
-    self.assertIs([m0, m1, m3, m4], proto.repeated_nested_message)
+    self.assertListsEqual([m0, m1, m3, m4], proto.repeated_nested_message)
 
     # Test slice deletion.
     del proto.repeated_nested_message[2:]
-    self.assertIs([m0, m1], proto.repeated_nested_message)
+    self.assertListsEqual([m0, m1], proto.repeated_nested_message)
+
+    # Test extending.
+    n1 = unittest_pb2.TestAllTypes.NestedMessage(bb=1)
+    n2 = unittest_pb2.TestAllTypes.NestedMessage(bb=2)
+    proto.repeated_nested_message.extend([n1,n2])
+    self.assertEqual(4, len(proto.repeated_nested_message))
+    self.assertEqual(n1, proto.repeated_nested_message[2])
+    self.assertEqual(n2, proto.repeated_nested_message[3])
 
     # Test clearing.
     proto.ClearField('repeated_nested_message')
     self.assertTrue(not proto.repeated_nested_message)
     self.assertEqual(0, len(proto.repeated_nested_message))
 
+    # Test constructing an element while adding it.
+    proto.repeated_nested_message.add(bb=23)
+    self.assertEqual(1, len(proto.repeated_nested_message))
+    self.assertEqual(23, proto.repeated_nested_message[0].bb)
+
   def testHandWrittenReflection(self):
-    # TODO(robinson): We probably need a better way to specify
-    # protocol types by hand.  But then again, this isn't something
-    # we expect many people to do.  Hmm.
+    # Hand written extensions are only supported by the pure-Python
+    # implementation of the API.
+    if api_implementation.Type() != 'python':
+      return
+
     FieldDescriptor = descriptor.FieldDescriptor
     foo_field_descriptor = FieldDescriptor(
         name='foo_field', full_name='MyProto.foo_field',
@@ -894,7 +994,7 @@ class ReflectionTest(unittest.TestCase):
     self.assertTrue(not toplevel.HasField('submessage'))
     foreign = toplevel.submessage.Extensions[
         more_extensions_pb2.repeated_message_extension].add()
-    self.assertTrue(foreign is toplevel.submessage.Extensions[
+    self.assertEqual(foreign, toplevel.submessage.Extensions[
         more_extensions_pb2.repeated_message_extension][0])
     self.assertTrue(toplevel.HasField('submessage'))
 
@@ -997,6 +1097,12 @@ class ReflectionTest(unittest.TestCase):
     self.assertEqual(123, proto2.repeated_nested_message[1].bb)
     self.assertEqual(321, proto2.repeated_nested_message[2].bb)
 
+    proto3 = unittest_pb2.TestAllTypes()
+    proto3.repeated_nested_message.MergeFrom(proto2.repeated_nested_message)
+    self.assertEqual(999, proto3.repeated_nested_message[0].bb)
+    self.assertEqual(123, proto3.repeated_nested_message[1].bb)
+    self.assertEqual(321, proto3.repeated_nested_message[2].bb)
+
   def testMergeFromAllFields(self):
     # With all fields set.
     proto1 = unittest_pb2.TestAllTypes()
@@ -1126,6 +1232,15 @@ class ReflectionTest(unittest.TestCase):
     self.assertEqual(2, proto1.optional_int32)
     self.assertEqual('important-text', proto1.optional_string)
 
+  def testCopyFromBadType(self):
+    # The python implementation doesn't raise an exception in this
+    # case. In theory it should.
+    if api_implementation.Type() == 'python':
+      return
+    proto1 = unittest_pb2.TestAllTypes()
+    proto2 = unittest_pb2.TestAllExtensions()
+    self.assertRaises(TypeError, proto1.CopyFrom, proto2)
+
   def testClear(self):
     proto = unittest_pb2.TestAllTypes()
     test_util.SetAllFields(proto)
@@ -1231,9 +1346,10 @@ class ReflectionTest(unittest.TestCase):
     proto.optional_string = str('Testing')
     self.assertEqual(proto.optional_string, unicode('Testing'))
 
-    # Values of type 'str' are also accepted as long as they can be encoded in
-    # UTF-8.
-    self.assertEqual(type(proto.optional_string), str)
+    if api_implementation.Type() == 'python':
+      # Values of type 'str' are also accepted as long as they can be
+      # encoded in UTF-8.
+      self.assertEqual(type(proto.optional_string), str)
 
     # Try to assign a 'str' value which contains bytes that aren't 7-bit ASCII.
     self.assertRaises(ValueError,
@@ -1271,7 +1387,7 @@ class ReflectionTest(unittest.TestCase):
     # Check that the type_id is the same as the tag ID in the .proto file.
     self.assertEqual(raw.item[0].type_id, 1547769)
 
-    # Check the actually bytes on the wire.
+    # Check the actual bytes on the wire.
     self.assertTrue(
         raw.item[0].message.endswith(test_utf8_bytes))
     message2.MergeFromString(raw.item[0].message)
@@ -1279,10 +1395,23 @@ class ReflectionTest(unittest.TestCase):
     self.assertEqual(type(message2.str), unicode)
     self.assertEqual(message2.str, test_utf8)
 
-    # How about if the bytes on the wire aren't a valid UTF-8 encoded string.
+    # The pure Python API throws an exception on MergeFromString(),
+    # if any of the string fields of the message can't be UTF-8 decoded.
+    # The C++ implementation of the API has no way to check that on
+    # MergeFromString and thus has no way to throw the exception.
+    #
+    # The pure Python API always returns objects of type 'unicode' (UTF-8
+    # encoded), or 'str' (in 7 bit ASCII).
     bytes = raw.item[0].message.replace(
         test_utf8_bytes, len(test_utf8_bytes) * '\xff')
-    self.assertRaises(UnicodeDecodeError, message2.MergeFromString, bytes)
+
+    unicode_decode_failed = False
+    try:
+      message2.MergeFromString(bytes)
+    except UnicodeDecodeError, e:
+      unicode_decode_failed = True
+    string_field = message2.str
+    self.assertTrue(unicode_decode_failed or type(string_field) == str)
 
   def testEmptyNestedMessage(self):
     proto = unittest_pb2.TestAllTypes()
@@ -1325,6 +1454,9 @@ class TestAllTypesEqualityTest(unittest.TestCase):
     self.first_proto = unittest_pb2.TestAllTypes()
     self.second_proto = unittest_pb2.TestAllTypes()
 
+  def testNotHashable(self):
+    self.assertRaises(TypeError, hash, self.first_proto)
+
   def testSelfEquality(self):
     self.assertEqual(self.first_proto, self.first_proto)
 
@@ -1342,6 +1474,9 @@ class FullProtosEqualityTest(unittest.TestCase):
     test_util.SetAllFields(self.first_proto)
     test_util.SetAllFields(self.second_proto)
 
+  def testNotHashable(self):
+    self.assertRaises(TypeError, hash, self.first_proto)
+
   def testNoneNotEqual(self):
     self.assertNotEqual(self.first_proto, None)
     self.assertNotEqual(None, self.second_proto)
@@ -1410,9 +1545,6 @@ class FullProtosEqualityTest(unittest.TestCase):
     self.first_proto.ClearField('optional_nested_message')
     self.second_proto.optional_nested_message.ClearField('bb')
     self.assertNotEqual(self.first_proto, self.second_proto)
-    # TODO(robinson): Replace next two lines with method
-    # to set the "has" bit without changing the value,
-    # if/when such a method exists.
     self.first_proto.optional_nested_message.bb = 0
     self.first_proto.optional_nested_message.ClearField('bb')
     self.assertEqual(self.first_proto, self.second_proto)
@@ -1477,6 +1609,14 @@ class ByteSizeTest(unittest.TestCase):
   def testEmptyMessage(self):
     self.assertEqual(0, self.proto.ByteSize())
 
+  def testSizedOnKwargs(self):
+    # Use a separate message to ensure testing right after creation.
+    proto = unittest_pb2.TestAllTypes()
+    self.assertEqual(0, proto.ByteSize())
+    proto_kwargs = unittest_pb2.TestAllTypes(optional_int64 = 1)
+    # One byte for the tag, one to encode varint 1.
+    self.assertEqual(2, proto_kwargs.ByteSize())
+
   def testVarints(self):
     def Test(i, expected_varint_size):
       self.proto.Clear()
@@ -1668,10 +1808,13 @@ class ByteSizeTest(unittest.TestCase):
     self.assertEqual(3, self.proto.ByteSize())
     self.proto.ClearField('optional_foreign_message')
     self.assertEqual(0, self.proto.ByteSize())
-    child = self.proto.optional_foreign_message
-    self.proto.ClearField('optional_foreign_message')
-    child.c = 128
-    self.assertEqual(0, self.proto.ByteSize())
+
+    if api_implementation.Type() == 'python':
+      # This is only possible in pure-Python implementation of the API.
+      child = self.proto.optional_foreign_message
+      self.proto.ClearField('optional_foreign_message')
+      child.c = 128
+      self.assertEqual(0, self.proto.ByteSize())
 
     # Test within extension.
     extension = more_extensions_pb2.optional_message_extension
@@ -1737,7 +1880,6 @@ class ByteSizeTest(unittest.TestCase):
     self.assertEqual(19, self.packed_extended_proto.ByteSize())
 
 
-# TODO(robinson): We need cross-language serialization consistency tests.
 # Issues to be sure to cover include:
 #   * Handling of unrecognized tags ("uninterpreted_bytes").
 #   * Handling of MessageSets.
@@ -1792,6 +1934,10 @@ class SerializationTest(unittest.TestCase):
     self.assertEqual(first_proto, second_proto)
 
   def testParseTruncated(self):
+    # This test is only applicable for the Python implementation of the API.
+    if api_implementation.Type() != 'python':
+      return
+
     first_proto = unittest_pb2.TestAllTypes()
     test_util.SetAllFields(first_proto)
     serialized = first_proto.SerializeToString()
diff --git a/python/google/protobuf/internal/text_format_test.py b/python/google/protobuf/internal/text_format_test.py
index e0991cb1..a3547782 100755
--- a/python/google/protobuf/internal/text_format_test.py
+++ b/python/google/protobuf/internal/text_format_test.py
@@ -35,6 +35,7 @@
 __author__ = 'kenton@google.com (Kenton Varda)'
 
 import difflib
+import re
 
 import unittest
 from google.protobuf import text_format
@@ -95,12 +96,13 @@ class TextFormatTest(unittest.TestCase):
 
   def testPrintExotic(self):
     message = unittest_pb2.TestAllTypes()
-    message.repeated_int64.append(-9223372036854775808);
-    message.repeated_uint64.append(18446744073709551615);
-    message.repeated_double.append(123.456);
-    message.repeated_double.append(1.23e22);
-    message.repeated_double.append(1.23e-18);
-    message.repeated_string.append('\000\001\a\b\f\n\r\t\v\\\'\"');
+    message.repeated_int64.append(-9223372036854775808)
+    message.repeated_uint64.append(18446744073709551615)
+    message.repeated_double.append(123.456)
+    message.repeated_double.append(1.23e22)
+    message.repeated_double.append(1.23e-18)
+    message.repeated_string.append('\000\001\a\b\f\n\r\t\v\\\'"')
+    message.repeated_string.append(u'\u00fc\ua71f')
     self.CompareToGoldenText(
       self.RemoveRedundantZeros(text_format.MessageToString(message)),
       'repeated_int64: -9223372036854775808\n'
@@ -109,7 +111,95 @@ class TextFormatTest(unittest.TestCase):
       'repeated_double: 1.23e+22\n'
       'repeated_double: 1.23e-18\n'
       'repeated_string: '
-        '\"\\000\\001\\007\\010\\014\\n\\r\\t\\013\\\\\\\'\\\"\"\n')
+        '"\\000\\001\\007\\010\\014\\n\\r\\t\\013\\\\\\\'\\""\n'
+      'repeated_string: "\\303\\274\\352\\234\\237"\n')
+
+  def testPrintNestedMessageAsOneLine(self):
+    message = unittest_pb2.TestAllTypes()
+    msg = message.repeated_nested_message.add()
+    msg.bb = 42;
+    self.CompareToGoldenText(
+        text_format.MessageToString(message, as_one_line=True),
+        'repeated_nested_message { bb: 42 }')
+
+  def testPrintRepeatedFieldsAsOneLine(self):
+    message = unittest_pb2.TestAllTypes()
+    message.repeated_int32.append(1)
+    message.repeated_int32.append(1)
+    message.repeated_int32.append(3)
+    message.repeated_string.append("Google")
+    message.repeated_string.append("Zurich")
+    self.CompareToGoldenText(
+        text_format.MessageToString(message, as_one_line=True),
+        'repeated_int32: 1 repeated_int32: 1 repeated_int32: 3 '
+        'repeated_string: "Google" repeated_string: "Zurich"')
+
+  def testPrintNestedNewLineInStringAsOneLine(self):
+    message = unittest_pb2.TestAllTypes()
+    message.optional_string = "a\nnew\nline"
+    self.CompareToGoldenText(
+        text_format.MessageToString(message, as_one_line=True),
+        'optional_string: "a\\nnew\\nline"')
+
+  def testPrintMessageSetAsOneLine(self):
+    message = unittest_mset_pb2.TestMessageSetContainer()
+    ext1 = unittest_mset_pb2.TestMessageSetExtension1.message_set_extension
+    ext2 = unittest_mset_pb2.TestMessageSetExtension2.message_set_extension
+    message.message_set.Extensions[ext1].i = 23
+    message.message_set.Extensions[ext2].str = 'foo'
+    self.CompareToGoldenText(
+        text_format.MessageToString(message, as_one_line=True),
+        'message_set {'
+        ' [protobuf_unittest.TestMessageSetExtension1] {'
+        ' i: 23'
+        ' }'
+        ' [protobuf_unittest.TestMessageSetExtension2] {'
+        ' str: \"foo\"'
+        ' }'
+        ' }')
+
+  def testPrintExoticAsOneLine(self):
+    message = unittest_pb2.TestAllTypes()
+    message.repeated_int64.append(-9223372036854775808)
+    message.repeated_uint64.append(18446744073709551615)
+    message.repeated_double.append(123.456)
+    message.repeated_double.append(1.23e22)
+    message.repeated_double.append(1.23e-18)
+    message.repeated_string.append('\000\001\a\b\f\n\r\t\v\\\'"')
+    message.repeated_string.append(u'\u00fc\ua71f')
+    self.CompareToGoldenText(
+      self.RemoveRedundantZeros(
+          text_format.MessageToString(message, as_one_line=True)),
+      'repeated_int64: -9223372036854775808'
+      ' repeated_uint64: 18446744073709551615'
+      ' repeated_double: 123.456'
+      ' repeated_double: 1.23e+22'
+      ' repeated_double: 1.23e-18'
+      ' repeated_string: '
+      '"\\000\\001\\007\\010\\014\\n\\r\\t\\013\\\\\\\'\\""'
+      ' repeated_string: "\\303\\274\\352\\234\\237"')
+
+  def testRoundTripExoticAsOneLine(self):
+    message = unittest_pb2.TestAllTypes()
+    message.repeated_int64.append(-9223372036854775808)
+    message.repeated_uint64.append(18446744073709551615)
+    message.repeated_double.append(123.456)
+    message.repeated_double.append(1.23e22)
+    message.repeated_double.append(1.23e-18)
+    message.repeated_string.append('\000\001\a\b\f\n\r\t\v\\\'"')
+    message.repeated_string.append(u'\u00fc\ua71f')
+
+    wire_text = text_format.MessageToString(message, as_one_line=True)
+    parsed_message = unittest_pb2.TestAllTypes()
+    text_format.Merge(wire_text, parsed_message)
+    self.assertEquals(message, parsed_message)
+
+  def testPrintRawUtf8String(self):
+    message = unittest_pb2.TestAllTypes()
+    message.repeated_string.append(u'\u00fc\ua71f')
+    self.CompareToGoldenText(
+        text_format.MessageToString(message, as_utf8 = True),
+        'repeated_string: "\303\274\352\234\237"\n')
 
   def testMessageToString(self):
     message = unittest_pb2.ForeignMessage()
@@ -119,8 +209,12 @@ class TextFormatTest(unittest.TestCase):
   def RemoveRedundantZeros(self, text):
     # Some platforms print 1e+5 as 1e+005.  This is fine, but we need to remove
     # these zeros in order to match the golden file.
-    return text.replace('e+0','e+').replace('e+0','e+') \
+    text = text.replace('e+0','e+').replace('e+0','e+') \
                .replace('e-0','e-').replace('e-0','e-')
+    # Floating point fields are printed with .0 suffix even if they are
+    # actualy integer numbers.
+    text = re.compile('\.0$', re.MULTILINE).sub('', text)
+    return text
 
   def testMergeGolden(self):
     golden_text = '\n'.join(self.ReadGolden('text_format_unittest_data.txt'))
@@ -191,8 +285,11 @@ class TextFormatTest(unittest.TestCase):
             'repeated_double: 1.23e+22\n'
             'repeated_double: 1.23e-18\n'
             'repeated_string: \n'
-            '\"\\000\\001\\007\\010\\014\\n\\r\\t\\013\\\\\\\'\\\"\"\n'
-            'repeated_string: "foo" \'corge\' "grault"')
+            '"\\000\\001\\007\\010\\014\\n\\r\\t\\013\\\\\\\'\\""\n'
+            'repeated_string: "foo" \'corge\' "grault"\n'
+            'repeated_string: "\\303\\274\\352\\234\\237"\n'
+            'repeated_string: "\\xc3\\xbc"\n'
+            'repeated_string: "\xc3\xbc"\n')
     text_format.Merge(text, message)
 
     self.assertEqual(-9223372036854775808, message.repeated_int64[0])
@@ -201,8 +298,30 @@ class TextFormatTest(unittest.TestCase):
     self.assertEqual(1.23e22, message.repeated_double[1])
     self.assertEqual(1.23e-18, message.repeated_double[2])
     self.assertEqual(
-        '\000\001\a\b\f\n\r\t\v\\\'\"', message.repeated_string[0])
+        '\000\001\a\b\f\n\r\t\v\\\'"', message.repeated_string[0])
     self.assertEqual('foocorgegrault', message.repeated_string[1])
+    self.assertEqual(u'\u00fc\ua71f', message.repeated_string[2])
+    self.assertEqual(u'\u00fc', message.repeated_string[3])
+
+  def testMergeEmptyText(self):
+    message = unittest_pb2.TestAllTypes()
+    text = ''
+    text_format.Merge(text, message)
+    self.assertEquals(unittest_pb2.TestAllTypes(), message)
+
+  def testMergeInvalidUtf8(self):
+    message = unittest_pb2.TestAllTypes()
+    text = 'repeated_string: "\\xc3\\xc3"'
+    self.assertRaises(text_format.ParseError, text_format.Merge, text, message)
+
+  def testMergeSingleWord(self):
+    message = unittest_pb2.TestAllTypes()
+    text = 'foo'
+    self.assertRaisesWithMessage(
+        text_format.ParseError,
+        ('1:1 : Message type "protobuf_unittest.TestAllTypes" has no field named '
+         '"foo".'),
+        text_format.Merge, text, message)
 
   def testMergeUnknownField(self):
     message = unittest_pb2.TestAllTypes()
@@ -297,7 +416,8 @@ class TokenizerTest(unittest.TestCase):
             'identifiER_4 : 1.1e+2 ID5:-0.23 ID6:\'aaaa\\\'bbbb\'\n'
             'ID7 : "aa\\"bb"\n\n\n\n ID8: {A:inf B:-inf C:true D:false}\n'
             'ID9: 22 ID10: -111111111111111111 ID11: -22\n'
-            'ID12: 2222222222222222222')
+            'ID12: 2222222222222222222 '
+            'false_bool:  0 true_BOOL:t \n true_bool1:  1 false_BOOL1:f ' )
     tokenizer = text_format._Tokenizer(text)
     methods = [(tokenizer.ConsumeIdentifier, 'identifier1'),
                ':',
@@ -347,7 +467,19 @@ class TokenizerTest(unittest.TestCase):
                (tokenizer.ConsumeInt32, -22),
                (tokenizer.ConsumeIdentifier, 'ID12'),
                ':',
-               (tokenizer.ConsumeUint64, 2222222222222222222)]
+               (tokenizer.ConsumeUint64, 2222222222222222222),
+               (tokenizer.ConsumeIdentifier, 'false_bool'),
+               ':',
+               (tokenizer.ConsumeBool, False),
+               (tokenizer.ConsumeIdentifier, 'true_BOOL'),
+               ':',
+               (tokenizer.ConsumeBool, True),
+               (tokenizer.ConsumeIdentifier, 'true_bool1'),
+               ':',
+               (tokenizer.ConsumeBool, True),
+               (tokenizer.ConsumeIdentifier, 'false_BOOL1'),
+               ':',
+               (tokenizer.ConsumeBool, False)]
 
     i = 0
     while not tokenizer.AtEnd():
diff --git a/python/google/protobuf/message.py b/python/google/protobuf/message.py
index f8398474..54cf35ea 100755
--- a/python/google/protobuf/message.py
+++ b/python/google/protobuf/message.py
@@ -67,6 +67,11 @@ class Message(object):
 
   DESCRIPTOR = None
 
+  def __deepcopy__(self, memo=None):
+    clone = type(self)()
+    clone.MergeFrom(self)
+    return clone
+
   def __eq__(self, other_msg):
     raise NotImplementedError
 
@@ -74,9 +79,15 @@ class Message(object):
     # 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):
     raise NotImplementedError
 
+  def __unicode__(self):
+    raise NotImplementedError
+
   def MergeFrom(self, other_msg):
     """Merges the contents of the specified message into current message.
 
diff --git a/python/google/protobuf/pyext/python-proto2.cc b/python/google/protobuf/pyext/python-proto2.cc
new file mode 100644
index 00000000..f2799e62
--- /dev/null
+++ b/python/google/protobuf/pyext/python-proto2.cc
@@ -0,0 +1,1658 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// 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.
+
+// Author: petar@google.com (Petar Petrov)
+
+#include <Python.h>
+#include <map>
+#include <string>
+#include <vector>
+
+#include <google/protobuf/stubs/common.h>
+#include <google/protobuf/pyext/python_descriptor.h>
+#include <google/protobuf/io/coded_stream.h>
+#include <google/protobuf/descriptor.h>
+#include <google/protobuf/dynamic_message.h>
+#include <google/protobuf/message.h>
+#include <google/protobuf/unknown_field_set.h>
+#include <google/protobuf/pyext/python_protobuf.h>
+
+/* Is 64bit */
+#define IS_64BIT (SIZEOF_LONG == 8)
+
+#define FIELD_BELONGS_TO_MESSAGE(field_descriptor, message) \
+    ((message)->GetDescriptor() == (field_descriptor)->containing_type())
+
+#define FIELD_IS_REPEATED(field_descriptor)                 \
+    ((field_descriptor)->label() == google::protobuf::FieldDescriptor::LABEL_REPEATED)
+
+#define GOOGLE_CHECK_GET_INT32(arg, value)                         \
+    int32 value;                                            \
+    if (!CheckAndGetInteger(arg, &value, kint32min_py, kint32max_py)) { \
+      return NULL;                                          \
+    }
+
+#define GOOGLE_CHECK_GET_INT64(arg, value)                         \
+    int64 value;                                            \
+    if (!CheckAndGetInteger(arg, &value, kint64min_py, kint64max_py)) { \
+      return NULL;                                          \
+    }
+
+#define GOOGLE_CHECK_GET_UINT32(arg, value)                        \
+    uint32 value;                                           \
+    if (!CheckAndGetInteger(arg, &value, kPythonZero, kuint32max_py)) { \
+      return NULL;                                          \
+    }
+
+#define GOOGLE_CHECK_GET_UINT64(arg, value)                        \
+    uint64 value;                                           \
+    if (!CheckAndGetInteger(arg, &value, kPythonZero, kuint64max_py)) { \
+      return NULL;                                          \
+    }
+
+#define GOOGLE_CHECK_GET_FLOAT(arg, value)                         \
+    float value;                                            \
+    if (!CheckAndGetFloat(arg, &value)) {                   \
+      return NULL;                                          \
+    }                                                       \
+
+#define GOOGLE_CHECK_GET_DOUBLE(arg, value)                        \
+    double value;                                           \
+    if (!CheckAndGetDouble(arg, &value)) {                  \
+      return NULL;                                          \
+    }
+
+#define GOOGLE_CHECK_GET_BOOL(arg, value)                          \
+    bool value;                                             \
+    if (!CheckAndGetBool(arg, &value)) {                    \
+      return NULL;                                          \
+    }
+
+#define C(str) const_cast<char*>(str)
+
+// --- Globals:
+
+// Constants used for integer type range checking.
+static PyObject* kPythonZero;
+static PyObject* kint32min_py;
+static PyObject* kint32max_py;
+static PyObject* kuint32max_py;
+static PyObject* kint64min_py;
+static PyObject* kint64max_py;
+static PyObject* kuint64max_py;
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+// --- Support Routines:
+
+static void AddConstants(PyObject* module) {
+  struct NameValue {
+    char* name;
+    int32 value;
+  } constants[] = {
+    // Labels:
+    {"LABEL_OPTIONAL", google::protobuf::FieldDescriptor::LABEL_OPTIONAL},
+    {"LABEL_REQUIRED", google::protobuf::FieldDescriptor::LABEL_REQUIRED},
+    {"LABEL_REPEATED", google::protobuf::FieldDescriptor::LABEL_REPEATED},
+    // CPP types:
+    {"CPPTYPE_MESSAGE", google::protobuf::FieldDescriptor::CPPTYPE_MESSAGE},
+    // Field Types:
+    {"TYPE_MESSAGE", google::protobuf::FieldDescriptor::TYPE_MESSAGE},
+    // End.
+    {NULL, 0}
+  };
+
+  for (NameValue* constant = constants;
+       constant->name != NULL; constant++) {
+    PyModule_AddIntConstant(module, constant->name, constant->value);
+  }
+}
+
+// --- CMessage Custom Type:
+
+// ------ Type Forward Declaration:
+
+struct CMessage;
+struct CMessage_Type;
+
+static void CMessageDealloc(CMessage* self);
+static int CMessageInit(CMessage* self, PyObject *args, PyObject *kwds);
+static PyObject* CMessageStr(CMessage* self);
+
+static PyObject* CMessage_AddMessage(CMessage* self, PyObject* args);
+static PyObject* CMessage_AddRepeatedScalar(CMessage* self, PyObject* args);
+static PyObject* CMessage_AssignRepeatedScalar(CMessage* self, PyObject* args);
+static PyObject* CMessage_ByteSize(CMessage* self, PyObject* args);
+static PyObject* CMessage_Clear(CMessage* self, PyObject* args);
+static PyObject* CMessage_ClearField(CMessage* self, PyObject* args);
+static PyObject* CMessage_ClearFieldByDescriptor(
+    CMessage* self, PyObject* args);
+static PyObject* CMessage_CopyFrom(CMessage* self, PyObject* args);
+static PyObject* CMessage_DebugString(CMessage* self, PyObject* args);
+static PyObject* CMessage_DeleteRepeatedField(CMessage* self, PyObject* args);
+static PyObject* CMessage_Equals(CMessage* self, PyObject* args);
+static PyObject* CMessage_FieldLength(CMessage* self, PyObject* args);
+static PyObject* CMessage_FindInitializationErrors(CMessage* self);
+static PyObject* CMessage_GetRepeatedMessage(CMessage* self, PyObject* args);
+static PyObject* CMessage_GetRepeatedScalar(CMessage* self, PyObject* args);
+static PyObject* CMessage_GetScalar(CMessage* self, PyObject* args);
+static PyObject* CMessage_HasField(CMessage* self, PyObject* args);
+static PyObject* CMessage_HasFieldByDescriptor(CMessage* self, PyObject* args);
+static PyObject* CMessage_IsInitialized(CMessage* self, PyObject* args);
+static PyObject* CMessage_ListFields(CMessage* self, PyObject* args);
+static PyObject* CMessage_MergeFrom(CMessage* self, PyObject* args);
+static PyObject* CMessage_MergeFromString(CMessage* self, PyObject* args);
+static PyObject* CMessage_MutableMessage(CMessage* self, PyObject* args);
+static PyObject* CMessage_NewSubMessage(CMessage* self, PyObject* args);
+static PyObject* CMessage_SetScalar(CMessage* self, PyObject* args);
+static PyObject* CMessage_SerializePartialToString(
+    CMessage* self, PyObject* args);
+static PyObject* CMessage_SerializeToString(CMessage* self, PyObject* args);
+static PyObject* CMessage_SetInParent(CMessage* self, PyObject* args);
+static PyObject* CMessage_SwapRepeatedFieldElements(
+    CMessage* self, PyObject* args);
+
+// ------ Object Definition:
+
+typedef struct CMessage {
+  PyObject_HEAD
+
+  struct CMessage* parent;  // NULL if wasn't created from another message.
+  CFieldDescriptor* parent_field;
+  const char* full_name;
+  google::protobuf::Message* message;
+  bool free_message;
+  bool read_only;
+} CMessage;
+
+// ------ Method Table:
+
+#define CMETHOD(name, args, doc)   \
+  { C(#name), (PyCFunction)CMessage_##name, args, C(doc) }
+static PyMethodDef CMessageMethods[] = {
+  CMETHOD(AddMessage, METH_O,
+          "Adds a new message to a repeated composite field."),
+  CMETHOD(AddRepeatedScalar, METH_VARARGS,
+          "Adds a scalar to a repeated scalar field."),
+  CMETHOD(AssignRepeatedScalar, METH_VARARGS,
+          "Clears and sets the values of a repeated scalar field."),
+  CMETHOD(ByteSize, METH_NOARGS,
+          "Returns the size of the message in bytes."),
+  CMETHOD(Clear, METH_NOARGS,
+          "Clears a protocol message."),
+  CMETHOD(ClearField, METH_O,
+          "Clears a protocol message field by name."),
+  CMETHOD(ClearFieldByDescriptor, METH_O,
+          "Clears a protocol message field by descriptor."),
+  CMETHOD(CopyFrom, METH_O,
+          "Copies a protocol message into the current message."),
+  CMETHOD(DebugString, METH_NOARGS,
+          "Returns the debug string of a protocol message."),
+  CMETHOD(DeleteRepeatedField, METH_VARARGS,
+          "Deletes a slice of values from a repeated field."),
+  CMETHOD(Equals, METH_O,
+          "Checks if two protocol messages are equal (by identity)."),
+  CMETHOD(FieldLength, METH_O,
+          "Returns the number of elements in a repeated field."),
+  CMETHOD(FindInitializationErrors, METH_NOARGS,
+          "Returns the initialization errors of a message."),
+  CMETHOD(GetRepeatedMessage, METH_VARARGS,
+          "Returns a message from a repeated composite field."),
+  CMETHOD(GetRepeatedScalar, METH_VARARGS,
+          "Returns a scalar value from a repeated scalar field."),
+  CMETHOD(GetScalar, METH_O,
+          "Returns the scalar value of a field."),
+  CMETHOD(HasField, METH_O,
+          "Checks if a message field is set."),
+  CMETHOD(HasFieldByDescriptor, METH_O,
+          "Checks if a message field is set by given its descriptor"),
+  CMETHOD(IsInitialized, METH_NOARGS,
+          "Checks if all required fields of a protocol message are set."),
+  CMETHOD(ListFields, METH_NOARGS,
+          "Lists all set fields of a message."),
+  CMETHOD(MergeFrom, METH_O,
+          "Merges a protocol message into the current message."),
+  CMETHOD(MergeFromString, METH_O,
+          "Merges a serialized message into the current message."),
+  CMETHOD(MutableMessage, METH_O,
+          "Returns a new instance of a nested protocol message."),
+  CMETHOD(NewSubMessage, METH_O,
+          "Creates and returns a python message given the descriptor of a "
+          "composite field of the current message."),
+  CMETHOD(SetScalar, METH_VARARGS,
+          "Sets the value of a singular scalar field."),
+  CMETHOD(SerializePartialToString, METH_VARARGS,
+          "Serializes the message to a string, even if it isn't initialized."),
+  CMETHOD(SerializeToString, METH_NOARGS,
+          "Serializes the message to a string, only for initialized messages."),
+  CMETHOD(SetInParent, METH_NOARGS,
+          "Sets the has bit of the given field in its parent message."),
+  CMETHOD(SwapRepeatedFieldElements, METH_VARARGS,
+          "Swaps the elements in two positions in a repeated field."),
+  { NULL, NULL }
+};
+#undef CMETHOD
+
+static PyMemberDef CMessageMembers[] = {
+  { C("full_name"), T_STRING, offsetof(CMessage, full_name), 0, "Full name" },
+  { NULL }
+};
+
+// ------ Type Definition:
+
+// The definition for the type object that captures the type of CMessage
+// in Python.
+PyTypeObject CMessage_Type = {
+  PyObject_HEAD_INIT(&PyType_Type)
+  0,
+  C("google3.net.google.protobuf.python.internal."
+    "_net_proto2___python."
+    "CMessage"),                       // tp_name
+  sizeof(CMessage),                    //  tp_basicsize
+  0,                                   //  tp_itemsize
+  (destructor)CMessageDealloc,         //  tp_dealloc
+  0,                                   //  tp_print
+  0,                                   //  tp_getattr
+  0,                                   //  tp_setattr
+  0,                                   //  tp_compare
+  0,                                   //  tp_repr
+  0,                                   //  tp_as_number
+  0,                                   //  tp_as_sequence
+  0,                                   //  tp_as_mapping
+  0,                                   //  tp_hash
+  0,                                   //  tp_call
+  (reprfunc)CMessageStr,               //  tp_str
+  0,                                   //  tp_getattro
+  0,                                   //  tp_setattro
+  0,                                   //  tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                  //  tp_flags
+  C("A ProtocolMessage"),              //  tp_doc
+  0,                                   //  tp_traverse
+  0,                                   //  tp_clear
+  0,                                   //  tp_richcompare
+  0,                                   //  tp_weaklistoffset
+  0,                                   //  tp_iter
+  0,                                   //  tp_iternext
+  CMessageMethods,                     //  tp_methods
+  CMessageMembers,                     //  tp_members
+  0,                                   //  tp_getset
+  0,                                   //  tp_base
+  0,                                   //  tp_dict
+  0,                                   //  tp_descr_get
+  0,                                   //  tp_descr_set
+  0,                                   //  tp_dictoffset
+  (initproc)CMessageInit,              //  tp_init
+  PyType_GenericAlloc,                 //  tp_alloc
+  PyType_GenericNew,                   //  tp_new
+  PyObject_Del,                        //  tp_free
+};
+
+// ------ Helper Functions:
+
+static void FormatTypeError(PyObject* arg, char* expected_types) {
+  PyObject* s = PyObject_Str(PyObject_Type(arg));
+  PyObject* repr = PyObject_Repr(PyObject_Type(arg));
+  PyErr_Format(PyExc_TypeError,
+               "%.100s has type %.100s, but expected one of: %s",
+               PyString_AS_STRING(repr),
+               PyString_AS_STRING(s),
+               expected_types);
+  Py_DECREF(s);
+  Py_DECREF(repr);
+}
+
+template <class T>
+static bool CheckAndGetInteger(
+    PyObject* arg, T* value, PyObject* min, PyObject* max) {
+  bool is_long = PyLong_Check(arg);
+  if (!PyInt_Check(arg) && !is_long) {
+    FormatTypeError(arg, "int, long");
+    return false;
+  }
+
+  if (PyObject_Compare(min, arg) > 0 || PyObject_Compare(max, arg) < 0) {
+    PyObject* s = PyObject_Str(arg);
+    PyErr_Format(PyExc_ValueError,
+                 "Value out of range: %s",
+                 PyString_AS_STRING(s));
+    Py_DECREF(s);
+    return false;
+  }
+  if (is_long) {
+    if (min == kPythonZero) {
+      *value = static_cast<T>(PyLong_AsUnsignedLongLong(arg));
+    } else {
+      *value = static_cast<T>(PyLong_AsLongLong(arg));
+    }
+  } else {
+    *value = static_cast<T>(PyInt_AsLong(arg));
+  }
+  return true;
+}
+
+static bool CheckAndGetDouble(PyObject* arg, double* value) {
+  if (!PyInt_Check(arg) && !PyLong_Check(arg) &&
+      !PyFloat_Check(arg)) {
+    FormatTypeError(arg, "int, long, float");
+    return false;
+  }
+  *value = PyFloat_AsDouble(arg);
+  return true;
+}
+
+static bool CheckAndGetFloat(PyObject* arg, float* value) {
+  double double_value;
+  if (!CheckAndGetDouble(arg, &double_value)) {
+    return false;
+  }
+  *value = static_cast<float>(double_value);
+  return true;
+}
+
+static bool CheckAndGetBool(PyObject* arg, bool* value) {
+  if (!PyInt_Check(arg) && !PyBool_Check(arg) && !PyLong_Check(arg)) {
+    FormatTypeError(arg, "int, long, bool");
+    return false;
+  }
+  *value = static_cast<bool>(PyInt_AsLong(arg));
+  return true;
+}
+
+google::protobuf::DynamicMessageFactory* global_message_factory = NULL;
+static const google::protobuf::Message* CreateMessage(const char* message_type) {
+  string message_name(message_type);
+  const google::protobuf::Descriptor* descriptor =
+      GetDescriptorPool()->FindMessageTypeByName(message_name);
+  if (descriptor == NULL) {
+    return NULL;
+  }
+  return global_message_factory->GetPrototype(descriptor);
+}
+
+static bool CheckAndSetString(
+    PyObject* arg, google::protobuf::Message* message,
+    const google::protobuf::FieldDescriptor* descriptor,
+    const google::protobuf::Reflection* reflection,
+    bool append,
+    int index) {
+  GOOGLE_DCHECK(descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING ||
+         descriptor->type() == google::protobuf::FieldDescriptor::TYPE_BYTES);
+  if (descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING) {
+    if (!PyString_Check(arg) && !PyUnicode_Check(arg)) {
+      FormatTypeError(arg, "str, unicode");
+      return false;
+    }
+
+    if (PyString_Check(arg)) {
+      PyObject* unicode = PyUnicode_FromEncodedObject(arg, "ascii", NULL);
+      if (unicode == NULL) {
+        PyObject* repr = PyObject_Repr(arg);
+        PyErr_Format(PyExc_ValueError,
+                     "%s has type str, but isn't in 7-bit ASCII "
+                     "encoding. Non-ASCII strings must be converted to "
+                     "unicode objects before being added.",
+                     PyString_AS_STRING(repr));
+        Py_DECREF(repr);
+        return false;
+      } else {
+        Py_DECREF(unicode);
+      }
+    }
+  } else if (!PyString_Check(arg)) {
+    FormatTypeError(arg, "str");
+    return false;
+  }
+
+  PyObject* encoded_string = NULL;
+  if (descriptor->type() == google::protobuf::FieldDescriptor::TYPE_STRING) {
+    if (PyString_Check(arg)) {
+      encoded_string = PyString_AsEncodedObject(arg, "utf-8", NULL);
+    } else {
+      encoded_string = PyUnicode_AsEncodedObject(arg, "utf-8", NULL);
+    }
+  } else {
+    // In this case field type is "bytes".
+    encoded_string = arg;
+    Py_INCREF(encoded_string);
+  }
+
+  if (encoded_string == NULL) {
+    return false;
+  }
+
+  char* value;
+  Py_ssize_t value_len;
+  if (PyString_AsStringAndSize(encoded_string, &value, &value_len) < 0) {
+    Py_DECREF(encoded_string);
+    return false;
+  }
+
+  string value_string(value, value_len);
+  if (append) {
+    reflection->AddString(message, descriptor, value_string);
+  } else if (index < 0) {
+    reflection->SetString(message, descriptor, value_string);
+  } else {
+    reflection->SetRepeatedString(message, descriptor, index, value_string);
+  }
+  Py_DECREF(encoded_string);
+  return true;
+}
+
+static PyObject* ToStringObject(
+    const google::protobuf::FieldDescriptor* descriptor, string value) {
+  if (descriptor->type() != google::protobuf::FieldDescriptor::TYPE_STRING) {
+    return PyString_FromStringAndSize(value.c_str(), value.length());
+  }
+
+  PyObject* result = PyUnicode_DecodeUTF8(value.c_str(), value.length(), NULL);
+  // If the string can't be decoded in UTF-8, just return a string object that
+  // contains the raw bytes. This can't happen if the value was assigned using
+  // the members of the Python message object, but can happen if the values were
+  // parsed from the wire (binary).
+  if (result == NULL) {
+    PyErr_Clear();
+    result = PyString_FromStringAndSize(value.c_str(), value.length());
+  }
+  return result;
+}
+
+static void AssureWritable(CMessage* self) {
+  if (self == NULL ||
+      self->parent == NULL ||
+      self->parent_field == NULL) {
+    return;
+  }
+
+  if (!self->read_only) {
+    return;
+  }
+
+  AssureWritable(self->parent);
+
+  google::protobuf::Message* message = self->parent->message;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+  self->message = reflection->MutableMessage(
+      message, self->parent_field->descriptor, global_message_factory);
+  self->read_only = false;
+  self->parent = NULL;
+  self->parent_field = NULL;
+}
+
+static PyObject* InternalGetScalar(
+    google::protobuf::Message* message,
+    const google::protobuf::FieldDescriptor* field_descriptor) {
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+
+  if (!FIELD_BELONGS_TO_MESSAGE(field_descriptor, message)) {
+    PyErr_SetString(
+        PyExc_KeyError, "Field does not belong to message!");
+    return NULL;
+  }
+
+  PyObject* result = NULL;
+  switch (field_descriptor->cpp_type()) {
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT32: {
+      int32 value = reflection->GetInt32(*message, field_descriptor);
+      result = PyInt_FromLong(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT64: {
+      int64 value = reflection->GetInt64(*message, field_descriptor);
+#if IS_64BIT
+      result = PyInt_FromLong(value);
+#else
+      result = PyLong_FromLongLong(value);
+#endif
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT32: {
+      uint32 value = reflection->GetUInt32(*message, field_descriptor);
+#if IS_64BIT
+      result = PyInt_FromLong(value);
+#else
+      result = PyLong_FromLongLong(value);
+#endif
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT64: {
+      uint64 value = reflection->GetUInt64(*message, field_descriptor);
+#if IS_64BIT
+      if (value <= static_cast<uint64>(kint64max)) {
+        result = PyInt_FromLong(static_cast<uint64>(value));
+      }
+#else
+      if (value <= static_cast<uint32>(kint32max)) {
+        result = PyInt_FromLong(static_cast<uint32>(value));
+      }
+#endif
+      else {  // NOLINT
+        result = PyLong_FromUnsignedLongLong(value);
+      }
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_FLOAT: {
+      float value = reflection->GetFloat(*message, field_descriptor);
+      result = PyFloat_FromDouble(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_DOUBLE: {
+      double value = reflection->GetDouble(*message, field_descriptor);
+      result = PyFloat_FromDouble(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_BOOL: {
+      bool value = reflection->GetBool(*message, field_descriptor);
+      result = PyBool_FromLong(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_STRING: {
+      string value = reflection->GetString(*message, field_descriptor);
+      result = ToStringObject(field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_ENUM: {
+      if (!message->GetReflection()->HasField(*message, field_descriptor)) {
+        // Look for the value in the unknown fields.
+        google::protobuf::UnknownFieldSet* unknown_field_set =
+            message->GetReflection()->MutableUnknownFields(message);
+        for (int i = 0; i < unknown_field_set->field_count(); ++i) {
+          if (unknown_field_set->field(i).number() ==
+              field_descriptor->number()) {
+            result = PyInt_FromLong(unknown_field_set->field(i).varint());
+            break;
+          }
+        }
+      }
+
+      if (result == NULL) {
+        const google::protobuf::EnumValueDescriptor* enum_value =
+            message->GetReflection()->GetEnum(*message, field_descriptor);
+        result = PyInt_FromLong(enum_value->number());
+      }
+      break;
+    }
+    default:
+      PyErr_Format(
+          PyExc_SystemError, "Getting a value from a field of unknown type %d",
+          field_descriptor->cpp_type());
+  }
+
+  return result;
+}
+
+static PyObject* InternalSetScalar(
+    google::protobuf::Message* message, const google::protobuf::FieldDescriptor* field_descriptor,
+    PyObject* arg) {
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+
+  if (!FIELD_BELONGS_TO_MESSAGE(field_descriptor, message)) {
+    PyErr_SetString(
+        PyExc_KeyError, "Field does not belong to message!");
+    return NULL;
+  }
+
+  switch (field_descriptor->cpp_type()) {
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT32: {
+      GOOGLE_CHECK_GET_INT32(arg, value);
+      reflection->SetInt32(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT64: {
+      GOOGLE_CHECK_GET_INT64(arg, value);
+      reflection->SetInt64(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT32: {
+      GOOGLE_CHECK_GET_UINT32(arg, value);
+      reflection->SetUInt32(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT64: {
+      GOOGLE_CHECK_GET_UINT64(arg, value);
+      reflection->SetUInt64(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_FLOAT: {
+      GOOGLE_CHECK_GET_FLOAT(arg, value);
+      reflection->SetFloat(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_DOUBLE: {
+      GOOGLE_CHECK_GET_DOUBLE(arg, value);
+      reflection->SetDouble(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_BOOL: {
+      GOOGLE_CHECK_GET_BOOL(arg, value);
+      reflection->SetBool(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_STRING: {
+      if (!CheckAndSetString(
+          arg, message, field_descriptor, reflection, false, -1)) {
+        return NULL;
+      }
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_ENUM: {
+      GOOGLE_CHECK_GET_INT32(arg, value);
+      const google::protobuf::EnumDescriptor* enum_descriptor =
+          field_descriptor->enum_type();
+      const google::protobuf::EnumValueDescriptor* enum_value =
+          enum_descriptor->FindValueByNumber(value);
+      if (enum_value != NULL) {
+        reflection->SetEnum(message, field_descriptor, enum_value);
+      } else {
+        bool added = false;
+        // Add the value to the unknown fields.
+        google::protobuf::UnknownFieldSet* unknown_field_set =
+            message->GetReflection()->MutableUnknownFields(message);
+        for (int i = 0; i < unknown_field_set->field_count(); ++i) {
+          if (unknown_field_set->field(i).number() ==
+              field_descriptor->number()) {
+            unknown_field_set->mutable_field(i)->set_varint(value);
+            added = true;
+            break;
+          }
+        }
+
+        if (!added) {
+          unknown_field_set->AddVarint(field_descriptor->number(), value);
+        }
+        reflection->ClearField(message, field_descriptor);
+      }
+      break;
+    }
+    default:
+      PyErr_Format(
+          PyExc_SystemError, "Setting value to a field of unknown type %d",
+          field_descriptor->cpp_type());
+  }
+
+  Py_RETURN_NONE;
+}
+
+static PyObject* InternalAddRepeatedScalar(
+    google::protobuf::Message* message, const google::protobuf::FieldDescriptor* field_descriptor,
+    PyObject* arg) {
+
+  if (!FIELD_BELONGS_TO_MESSAGE(field_descriptor, message)) {
+    PyErr_SetString(
+        PyExc_KeyError, "Field does not belong to message!");
+    return NULL;
+  }
+
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+  switch (field_descriptor->cpp_type()) {
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT32: {
+      GOOGLE_CHECK_GET_INT32(arg, value);
+      reflection->AddInt32(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT64: {
+      GOOGLE_CHECK_GET_INT64(arg, value);
+      reflection->AddInt64(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT32: {
+      GOOGLE_CHECK_GET_UINT32(arg, value);
+      reflection->AddUInt32(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT64: {
+      GOOGLE_CHECK_GET_UINT64(arg, value);
+      reflection->AddUInt64(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_FLOAT: {
+      GOOGLE_CHECK_GET_FLOAT(arg, value);
+      reflection->AddFloat(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_DOUBLE: {
+      GOOGLE_CHECK_GET_DOUBLE(arg, value);
+      reflection->AddDouble(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_BOOL: {
+      GOOGLE_CHECK_GET_BOOL(arg, value);
+      reflection->AddBool(message, field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_STRING: {
+      if (!CheckAndSetString(
+          arg, message, field_descriptor, reflection, true, -1)) {
+        return NULL;
+      }
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_ENUM: {
+      GOOGLE_CHECK_GET_INT32(arg, value);
+      const google::protobuf::EnumDescriptor* enum_descriptor =
+          field_descriptor->enum_type();
+      const google::protobuf::EnumValueDescriptor* enum_value =
+          enum_descriptor->FindValueByNumber(value);
+      if (enum_value != NULL) {
+        reflection->AddEnum(message, field_descriptor, enum_value);
+      } else {
+        PyObject* s = PyObject_Str(arg);
+        PyErr_Format(PyExc_ValueError, "Unknown enum value: %s",
+                     PyString_AS_STRING(s));
+        Py_DECREF(s);
+        return NULL;
+      }
+      break;
+    }
+    default:
+      PyErr_Format(
+          PyExc_SystemError, "Adding value to a field of unknown type %d",
+          field_descriptor->cpp_type());
+  }
+
+  Py_RETURN_NONE;
+}
+
+static PyObject* InternalGetRepeatedScalar(
+    CMessage* cmessage, const google::protobuf::FieldDescriptor* field_descriptor,
+    int index) {
+  google::protobuf::Message* message = cmessage->message;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+
+  int field_size = reflection->FieldSize(*message, field_descriptor);
+  if (index < 0) {
+    index = field_size + index;
+  }
+  if (index < 0 || index >= field_size) {
+    PyErr_Format(PyExc_IndexError,
+                 "list assignment index (%d) out of range", index);
+    return NULL;
+  }
+
+  PyObject* result = NULL;
+  switch (field_descriptor->cpp_type()) {
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT32: {
+      int32 value = reflection->GetRepeatedInt32(
+          *message, field_descriptor, index);
+      result = PyInt_FromLong(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_INT64: {
+      int64 value = reflection->GetRepeatedInt64(
+          *message, field_descriptor, index);
+      result = PyLong_FromLongLong(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT32: {
+      uint32 value = reflection->GetRepeatedUInt32(
+          *message, field_descriptor, index);
+      result = PyLong_FromLongLong(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_UINT64: {
+      uint64 value = reflection->GetRepeatedUInt64(
+          *message, field_descriptor, index);
+      result = PyLong_FromUnsignedLongLong(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_FLOAT: {
+      float value = reflection->GetRepeatedFloat(
+          *message, field_descriptor, index);
+      result = PyFloat_FromDouble(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_DOUBLE: {
+      double value = reflection->GetRepeatedDouble(
+          *message, field_descriptor, index);
+      result = PyFloat_FromDouble(value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_BOOL: {
+      bool value = reflection->GetRepeatedBool(
+          *message, field_descriptor, index);
+      result = PyBool_FromLong(value ? 1 : 0);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_ENUM: {
+      const google::protobuf::EnumValueDescriptor* enum_value =
+          message->GetReflection()->GetRepeatedEnum(
+              *message, field_descriptor, index);
+      result = PyInt_FromLong(enum_value->number());
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_STRING: {
+      string value = reflection->GetRepeatedString(
+          *message, field_descriptor, index);
+      result = ToStringObject(field_descriptor, value);
+      break;
+    }
+    case google::protobuf::FieldDescriptor::CPPTYPE_MESSAGE: {
+      CMessage* py_cmsg = PyObject_New(CMessage, &CMessage_Type);
+      if (py_cmsg == NULL) {
+        return NULL;
+      }
+      const google::protobuf::Message& msg = reflection->GetRepeatedMessage(
+          *message, field_descriptor, index);
+      py_cmsg->parent = cmessage;
+      py_cmsg->full_name = field_descriptor->full_name().c_str();
+      py_cmsg->message = const_cast<google::protobuf::Message*>(&msg);
+      py_cmsg->free_message = false;
+      py_cmsg->read_only = false;
+      result = reinterpret_cast<PyObject*>(py_cmsg);
+      break;
+    }
+    default:
+      PyErr_Format(
+          PyExc_SystemError,
+          "Getting value from a repeated field of unknown type %d",
+          field_descriptor->cpp_type());
+  }
+
+  return result;
+}
+
+static PyObject* InternalGetRepeatedScalarSlice(
+    CMessage* cmessage, const google::protobuf::FieldDescriptor* field_descriptor,
+    PyObject* slice) {
+  Py_ssize_t from;
+  Py_ssize_t to;
+  Py_ssize_t step;
+  Py_ssize_t length;
+  bool return_list = false;
+  google::protobuf::Message* message = cmessage->message;
+
+  if (PyInt_Check(slice)) {
+    from = to = PyInt_AsLong(slice);
+  } else if (PyLong_Check(slice)) {
+    from = to = PyLong_AsLong(slice);
+  } else if (PySlice_Check(slice)) {
+    const google::protobuf::Reflection* reflection = message->GetReflection();
+    length = reflection->FieldSize(*message, field_descriptor);
+    PySlice_GetIndices(
+        reinterpret_cast<PySliceObject*>(slice), length, &from, &to, &step);
+    return_list = true;
+  } else {
+    PyErr_SetString(PyExc_TypeError, "list indices must be integers");
+    return NULL;
+  }
+
+  if (!return_list) {
+    return InternalGetRepeatedScalar(cmessage, field_descriptor, from);
+  }
+
+  PyObject* list = PyList_New(0);
+  if (list == NULL) {
+    return NULL;
+  }
+
+  if (from <= to) {
+    if (step < 0) return list;
+    for (Py_ssize_t index = from; index < to; index += step) {
+      if (index < 0 || index >= length) break;
+      PyObject* s = InternalGetRepeatedScalar(
+          cmessage, field_descriptor, index);
+      PyList_Append(list, s);
+      Py_DECREF(s);
+    }
+  } else {
+    if (step > 0) return list;
+    for (Py_ssize_t index = from; index > to; index += step) {
+      if (index < 0 || index >= length) break;
+      PyObject* s = InternalGetRepeatedScalar(
+          cmessage, field_descriptor, index);
+      PyList_Append(list, s);
+      Py_DECREF(s);
+    }
+  }
+  return list;
+}
+
+// ------ C Constructor/Destructor:
+
+static int CMessageInit(CMessage* self, PyObject *args, PyObject *kwds) {
+  self->message = NULL;
+  return 0;
+}
+
+static void CMessageDealloc(CMessage* self) {
+  if (self->free_message) {
+    if (self->read_only) {
+      PyErr_WriteUnraisable(reinterpret_cast<PyObject*>(self));
+    }
+    delete self->message;
+  }
+  self->ob_type->tp_free(reinterpret_cast<PyObject*>(self));
+}
+
+// ------ Methods:
+
+static PyObject* CMessage_Clear(CMessage* self, PyObject* args) {
+  AssureWritable(self);
+  self->message->Clear();
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_IsInitialized(CMessage* self, PyObject* args) {
+  return PyBool_FromLong(self->message->IsInitialized() ? 1 : 0);
+}
+
+static PyObject* CMessage_HasField(CMessage* self, PyObject* arg) {
+  char* field_name;
+  if (PyString_AsStringAndSize(arg, &field_name, NULL) < 0) {
+    return NULL;
+  }
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::Descriptor* descriptor = message->GetDescriptor();
+  const google::protobuf::FieldDescriptor* field_descriptor =
+      descriptor->FindFieldByName(field_name);
+  if (field_descriptor == NULL) {
+    PyErr_Format(PyExc_ValueError, "Unknown field %s.", field_name);
+    return NULL;
+  }
+
+  bool has_field =
+      message->GetReflection()->HasField(*message, field_descriptor);
+  return PyBool_FromLong(has_field ? 1 : 0);
+}
+
+static PyObject* CMessage_HasFieldByDescriptor(CMessage* self, PyObject* arg) {
+  CFieldDescriptor* cfield_descriptor = NULL;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg),
+                          &CFieldDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a field descriptor");
+    return NULL;
+  }
+  cfield_descriptor = reinterpret_cast<CFieldDescriptor*>(arg);
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::FieldDescriptor* field_descriptor =
+      cfield_descriptor->descriptor;
+
+  if (!FIELD_BELONGS_TO_MESSAGE(field_descriptor, message)) {
+    PyErr_SetString(PyExc_KeyError,
+                    "Field does not belong to message!");
+    return NULL;
+  }
+
+  if (FIELD_IS_REPEATED(field_descriptor)) {
+    PyErr_SetString(PyExc_KeyError,
+                    "Field is repeated. A singular method is required.");
+    return NULL;
+  }
+
+  bool has_field =
+      message->GetReflection()->HasField(*message, field_descriptor);
+  return PyBool_FromLong(has_field ? 1 : 0);
+}
+
+static PyObject* CMessage_ClearFieldByDescriptor(
+    CMessage* self, PyObject* arg) {
+  CFieldDescriptor* cfield_descriptor = NULL;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg),
+                          &CFieldDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a field descriptor");
+    return NULL;
+  }
+  cfield_descriptor = reinterpret_cast<CFieldDescriptor*>(arg);
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::FieldDescriptor* field_descriptor =
+      cfield_descriptor->descriptor;
+
+  if (!FIELD_BELONGS_TO_MESSAGE(field_descriptor, message)) {
+    PyErr_SetString(PyExc_KeyError,
+                    "Field does not belong to message!");
+    return NULL;
+  }
+
+  message->GetReflection()->ClearField(message, field_descriptor);
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_ClearField(CMessage* self, PyObject* arg) {
+  char* field_name;
+  if (PyString_AsStringAndSize(arg, &field_name, NULL) < 0) {
+    return NULL;
+  }
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::Descriptor* descriptor = message->GetDescriptor();
+  const google::protobuf::FieldDescriptor* field_descriptor =
+      descriptor->FindFieldByName(field_name);
+  if (field_descriptor == NULL) {
+    PyErr_Format(PyExc_ValueError, "Unknown field %s.", field_name);
+    return NULL;
+  }
+
+  message->GetReflection()->ClearField(message, field_descriptor);
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_GetScalar(CMessage* self, PyObject* arg) {
+  CFieldDescriptor* cdescriptor = NULL;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg),
+                          &CFieldDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a field descriptor");
+    return NULL;
+  }
+  cdescriptor = reinterpret_cast<CFieldDescriptor*>(arg);
+
+  google::protobuf::Message* message = self->message;
+  return InternalGetScalar(message, cdescriptor->descriptor);
+}
+
+static PyObject* CMessage_GetRepeatedScalar(CMessage* self, PyObject* args) {
+  CFieldDescriptor* cfield_descriptor;
+  PyObject* slice;
+  if (!PyArg_ParseTuple(args, C("O!O:GetRepeatedScalar"),
+                        &CFieldDescriptor_Type, &cfield_descriptor, &slice)) {
+    return NULL;
+  }
+
+  return InternalGetRepeatedScalarSlice(
+      self, cfield_descriptor->descriptor, slice);
+}
+
+static PyObject* CMessage_AssignRepeatedScalar(CMessage* self, PyObject* args) {
+  CFieldDescriptor* cfield_descriptor;
+  PyObject* slice;
+  if (!PyArg_ParseTuple(args, C("O!O:AssignRepeatedScalar"),
+                        &CFieldDescriptor_Type, &cfield_descriptor, &slice)) {
+    return NULL;
+  }
+
+  AssureWritable(self);
+  google::protobuf::Message* message = self->message;
+  message->GetReflection()->ClearField(message, cfield_descriptor->descriptor);
+
+  PyObject* iter = PyObject_GetIter(slice);
+  PyObject* next;
+  while ((next = PyIter_Next(iter)) != NULL) {
+    if (InternalAddRepeatedScalar(
+        message, cfield_descriptor->descriptor, next) == NULL) {
+      Py_DECREF(iter);
+      return NULL;
+    }
+  }
+  Py_DECREF(iter);
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_DeleteRepeatedField(CMessage* self, PyObject* args) {
+  CFieldDescriptor* cfield_descriptor;
+  PyObject* slice;
+  if (!PyArg_ParseTuple(args, C("O!O:DeleteRepeatedField"),
+                        &CFieldDescriptor_Type, &cfield_descriptor, &slice)) {
+    return NULL;
+  }
+  AssureWritable(self);
+
+  Py_ssize_t length, from, to, step, slice_length;
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::FieldDescriptor* field_descriptor =
+      cfield_descriptor->descriptor;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+  int min, max;
+  length = reflection->FieldSize(*message, field_descriptor);
+
+  if (PyInt_Check(slice) || PyLong_Check(slice)) {
+    from = to = PyLong_AsLong(slice);
+    if (from < 0) {
+      from = to = length + from;
+    }
+    step = 1;
+    min = max = from;
+
+    // Range check.
+    if (from < 0 || from >= length) {
+      PyErr_Format(PyExc_IndexError, "list assignment index out of range");
+      return NULL;
+    }
+  } else if (PySlice_Check(slice)) {
+    from = to = step = slice_length = 0;
+    PySlice_GetIndicesEx(
+        reinterpret_cast<PySliceObject*>(slice),
+        length, &from, &to, &step, &slice_length);
+    if (from < to) {
+      min = from;
+      max = to - 1;
+    } else {
+      min = to + 1;
+      max = from;
+    }
+  } else {
+    PyErr_SetString(PyExc_TypeError, "list indices must be integers");
+    return NULL;
+  }
+
+  Py_ssize_t i = from;
+  std::vector<bool> to_delete(length, false);
+  while (i >= min && i <= max) {
+    to_delete[i] = true;
+    i += step;
+  }
+
+  to = 0;
+  for (i = 0; i < length; ++i) {
+    if (!to_delete[i]) {
+      if (i != to) {
+        reflection->SwapElements(message, field_descriptor, i, to);
+      }
+      ++to;
+    }
+  }
+
+  while (i > to) {
+    reflection->RemoveLast(message, field_descriptor);
+    --i;
+  }
+
+  Py_RETURN_NONE;
+}
+
+
+static PyObject* CMessage_SetScalar(CMessage* self, PyObject* args) {
+  CFieldDescriptor* cfield_descriptor;
+  PyObject* arg;
+  if (!PyArg_ParseTuple(args, C("O!O:SetScalar"),
+                        &CFieldDescriptor_Type, &cfield_descriptor, &arg)) {
+    return NULL;
+  }
+  AssureWritable(self);
+
+  return InternalSetScalar(self->message, cfield_descriptor->descriptor, arg);
+}
+
+static PyObject* CMessage_AddRepeatedScalar(CMessage* self, PyObject* args) {
+  CFieldDescriptor* cfield_descriptor;
+  PyObject* value;
+  if (!PyArg_ParseTuple(args, C("O!O:AddRepeatedScalar"),
+                        &CFieldDescriptor_Type, &cfield_descriptor, &value)) {
+    return NULL;
+  }
+  AssureWritable(self);
+
+  return InternalAddRepeatedScalar(
+      self->message, cfield_descriptor->descriptor, value);
+}
+
+static PyObject* CMessage_FieldLength(CMessage* self, PyObject* arg) {
+  CFieldDescriptor* cfield_descriptor;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg),
+                          &CFieldDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a field descriptor");
+    return NULL;
+  }
+  cfield_descriptor = reinterpret_cast<CFieldDescriptor*>(arg);
+
+  google::protobuf::Message* message = self->message;
+  int length = message->GetReflection()->FieldSize(
+      *message, cfield_descriptor->descriptor);
+  return PyInt_FromLong(length);
+}
+
+static PyObject* CMessage_DebugString(CMessage* self, PyObject* args) {
+  return PyString_FromString(self->message->DebugString().c_str());
+}
+
+static PyObject* CMessage_SerializeToString(CMessage* self, PyObject* args) {
+  int size = self->message->ByteSize();
+  if (size <= 0) {
+    return PyString_FromString("");
+  }
+  PyObject* result = PyString_FromStringAndSize(NULL, size);
+  if (result == NULL) {
+    return NULL;
+  }
+  char* buffer = PyString_AS_STRING(result);
+  self->message->SerializeWithCachedSizesToArray(
+      reinterpret_cast<uint8*>(buffer));
+  return result;
+}
+
+static PyObject* CMessage_SerializePartialToString(
+    CMessage* self, PyObject* args) {
+  string contents;
+  self->message->SerializePartialToString(&contents);
+  return PyString_FromStringAndSize(contents.c_str(), contents.size());
+}
+
+static PyObject* CMessageStr(CMessage* self) {
+  char str[1024];
+  str[sizeof(str) - 1] = 0;
+  snprintf(str, sizeof(str) - 1, "CMessage: <%p>", self->message);
+  return PyString_FromString(str);
+}
+
+static PyObject* CMessage_MergeFrom(CMessage* self, PyObject* arg) {
+  CMessage* other_message;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg), &CMessage_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a message");
+    return NULL;
+  }
+
+  other_message = reinterpret_cast<CMessage*>(arg);
+  if (other_message->message->GetDescriptor() !=
+      self->message->GetDescriptor()) {
+    PyErr_Format(PyExc_TypeError,
+                 "Tried to merge from a message with a different type. "
+                 "to: %s, from: %s",
+                 self->message->GetDescriptor()->full_name().c_str(),
+                 other_message->message->GetDescriptor()->full_name().c_str());
+    return NULL;
+  }
+  AssureWritable(self);
+
+  self->message->MergeFrom(*other_message->message);
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_CopyFrom(CMessage* self, PyObject* arg) {
+  CMessage* other_message;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg), &CMessage_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a message");
+    return NULL;
+  }
+
+  other_message = reinterpret_cast<CMessage*>(arg);
+  if (other_message->message->GetDescriptor() !=
+      self->message->GetDescriptor()) {
+    PyErr_Format(PyExc_TypeError,
+                 "Tried to copy from a message with a different type. "
+                 "to: %s, from: %s",
+                 self->message->GetDescriptor()->full_name().c_str(),
+                 other_message->message->GetDescriptor()->full_name().c_str());
+    return NULL;
+  }
+
+  AssureWritable(self);
+
+  self->message->CopyFrom(*other_message->message);
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_MergeFromString(CMessage* self, PyObject* arg) {
+  const void* data;
+  Py_ssize_t data_length;
+  if (PyObject_AsReadBuffer(arg, &data, &data_length) < 0) {
+    return NULL;
+  }
+
+  AssureWritable(self);
+  google::protobuf::io::CodedInputStream input(
+      reinterpret_cast<const uint8*>(data), data_length);
+  bool success = self->message->MergePartialFromCodedStream(&input);
+  if (success) {
+    return PyInt_FromLong(self->message->ByteSize());
+  } else {
+    return PyInt_FromLong(-1);
+  }
+}
+
+static PyObject* CMessage_ByteSize(CMessage* self, PyObject* args) {
+  return PyLong_FromLong(self->message->ByteSize());
+}
+
+static PyObject* CMessage_SetInParent(CMessage* self, PyObject* args) {
+  AssureWritable(self);
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_SwapRepeatedFieldElements(
+    CMessage* self, PyObject* args) {
+  CFieldDescriptor* cfield_descriptor;
+  int index1, index2;
+  if (!PyArg_ParseTuple(args, C("O!ii:SwapRepeatedFieldElements"),
+                        &CFieldDescriptor_Type, &cfield_descriptor,
+                        &index1, &index2)) {
+    return NULL;
+  }
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+
+  reflection->SwapElements(
+      message, cfield_descriptor->descriptor, index1, index2);
+  Py_RETURN_NONE;
+}
+
+static PyObject* CMessage_AddMessage(CMessage* self, PyObject* arg) {
+  CFieldDescriptor* cfield_descriptor;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg),
+                          &CFieldDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a field descriptor");
+    return NULL;
+  }
+  cfield_descriptor = reinterpret_cast<CFieldDescriptor*>(arg);
+  AssureWritable(self);
+
+  CMessage* py_cmsg = PyObject_New(CMessage, &CMessage_Type);
+  if (py_cmsg == NULL) {
+    return NULL;
+  }
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+  google::protobuf::Message* sub_message =
+      reflection->AddMessage(message, cfield_descriptor->descriptor);
+
+  py_cmsg->parent = NULL;
+  py_cmsg->full_name = sub_message->GetDescriptor()->full_name().c_str();
+  py_cmsg->message = sub_message;
+  py_cmsg->free_message = false;
+  py_cmsg->read_only = false;
+  return reinterpret_cast<PyObject*>(py_cmsg);
+}
+
+static PyObject* CMessage_GetRepeatedMessage(CMessage* self, PyObject* args) {
+  CFieldDescriptor* cfield_descriptor;
+  PyObject* slice;
+  if (!PyArg_ParseTuple(args, C("O!O:GetRepeatedMessage"),
+                        &CFieldDescriptor_Type, &cfield_descriptor, &slice)) {
+    return NULL;
+  }
+
+  return InternalGetRepeatedScalarSlice(
+      self, cfield_descriptor->descriptor, slice);
+}
+
+static PyObject* CMessage_NewSubMessage(CMessage* self, PyObject* arg) {
+  CFieldDescriptor* cfield_descriptor;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg),
+                          &CFieldDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a field descriptor");
+    return NULL;
+  }
+  cfield_descriptor = reinterpret_cast<CFieldDescriptor*>(arg);
+
+  CMessage* py_cmsg = PyObject_New(CMessage, &CMessage_Type);
+  if (py_cmsg == NULL) {
+    return NULL;
+  }
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+  const google::protobuf::Message& sub_message =
+      reflection->GetMessage(*message, cfield_descriptor->descriptor,
+                             global_message_factory);
+
+  py_cmsg->full_name = sub_message.GetDescriptor()->full_name().c_str();
+  py_cmsg->parent = self;
+  py_cmsg->parent_field = cfield_descriptor;
+  py_cmsg->message = const_cast<google::protobuf::Message*>(&sub_message);
+  py_cmsg->free_message = false;
+  py_cmsg->read_only = true;
+  return reinterpret_cast<PyObject*>(py_cmsg);
+}
+
+static PyObject* CMessage_MutableMessage(CMessage* self, PyObject* arg) {
+  CFieldDescriptor* cfield_descriptor;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg),
+                          &CFieldDescriptor_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a field descriptor");
+    return NULL;
+  }
+  cfield_descriptor = reinterpret_cast<CFieldDescriptor*>(arg);
+  AssureWritable(self);
+
+  CMessage* py_cmsg = PyObject_New(CMessage, &CMessage_Type);
+  if (py_cmsg == NULL) {
+    return NULL;
+  }
+
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+  google::protobuf::Message* mutable_message =
+      reflection->MutableMessage(message, cfield_descriptor->descriptor,
+                                 global_message_factory);
+
+  py_cmsg->full_name = mutable_message->GetDescriptor()->full_name().c_str();
+  py_cmsg->message = mutable_message;
+  py_cmsg->free_message = false;
+  py_cmsg->read_only = false;
+  return reinterpret_cast<PyObject*>(py_cmsg);
+}
+
+static PyObject* CMessage_Equals(CMessage* self, PyObject* arg) {
+  CMessage* other_message;
+  if (!PyObject_TypeCheck(reinterpret_cast<PyObject *>(arg), &CMessage_Type)) {
+    PyErr_SetString(PyExc_TypeError, "Must be a message");
+    return NULL;
+  }
+  other_message = reinterpret_cast<CMessage*>(arg);
+
+  if (other_message->message == self->message) {
+    return PyBool_FromLong(1);
+  }
+
+  if (other_message->message->GetDescriptor() !=
+      self->message->GetDescriptor()) {
+    return PyBool_FromLong(0);
+  }
+
+  return PyBool_FromLong(1);
+}
+
+static PyObject* CMessage_ListFields(CMessage* self, PyObject* args) {
+  google::protobuf::Message* message = self->message;
+  const google::protobuf::Reflection* reflection = message->GetReflection();
+  vector<const google::protobuf::FieldDescriptor*> fields;
+  reflection->ListFields(*message, &fields);
+
+  PyObject* list = PyList_New(fields.size());
+  if (list == NULL) {
+    return NULL;
+  }
+
+  for (unsigned int i = 0; i < fields.size(); ++i) {
+    bool is_extension = fields[i]->is_extension();
+    PyObject* t = PyTuple_New(2);
+    if (t == NULL) {
+      Py_DECREF(list);
+      return NULL;
+    }
+
+    PyObject* is_extension_object = PyBool_FromLong(is_extension ? 1 : 0);
+
+    PyObject* field_name;
+    const string* s;
+    if (is_extension) {
+      s = &fields[i]->full_name();
+    } else {
+      s = &fields[i]->name();
+    }
+    field_name = PyString_FromStringAndSize(s->c_str(), s->length());
+    if (field_name == NULL) {
+      Py_DECREF(list);
+      Py_DECREF(t);
+      return NULL;
+    }
+
+    PyTuple_SET_ITEM(t, 0, is_extension_object);
+    PyTuple_SET_ITEM(t, 1, field_name);
+    PyList_SET_ITEM(list, i, t);
+  }
+
+  return list;
+}
+
+static PyObject* CMessage_FindInitializationErrors(CMessage* self) {
+  google::protobuf::Message* message = self->message;
+  vector<string> errors;
+  message->FindInitializationErrors(&errors);
+
+  PyObject* error_list = PyList_New(errors.size());
+  if (error_list == NULL) {
+    return NULL;
+  }
+  for (unsigned int i = 0; i < errors.size(); ++i) {
+    const string& error = errors[i];
+    PyObject* error_string = PyString_FromStringAndSize(
+        error.c_str(), error.length());
+    if (error_string == NULL) {
+      Py_DECREF(error_list);
+      return NULL;
+    }
+    PyList_SET_ITEM(error_list, i, error_string);
+  }
+  return error_list;
+}
+
+// ------ Python Constructor:
+
+PyObject* Python_NewCMessage(PyObject* ignored, PyObject* arg) {
+  const char* message_type = PyString_AsString(arg);
+  if (message_type == NULL) {
+    return NULL;
+  }
+
+  const google::protobuf::Message* message = CreateMessage(message_type);
+  if (message == NULL) {
+    PyErr_Format(PyExc_TypeError, "Couldn't create message of type %s!",
+                 message_type);
+    return NULL;
+  }
+
+  CMessage* py_cmsg = PyObject_New(CMessage, &CMessage_Type);
+  if (py_cmsg == NULL) {
+    return NULL;
+  }
+  py_cmsg->message = message->New();
+  py_cmsg->free_message = true;
+  py_cmsg->full_name = message->GetDescriptor()->full_name().c_str();
+  py_cmsg->read_only = false;
+  py_cmsg->parent = NULL;
+  py_cmsg->parent_field = NULL;
+  return reinterpret_cast<PyObject*>(py_cmsg);
+}
+
+// --- Module Functions (exposed to Python):
+
+PyMethodDef methods[] = {
+  { C("NewCMessage"), (PyCFunction)Python_NewCMessage,
+    METH_O,
+    C("Creates a new C++ protocol message, given its full name.") },
+  { C("NewCDescriptorPool"), (PyCFunction)Python_NewCDescriptorPool,
+    METH_NOARGS,
+    C("Creates a new C++ descriptor pool.") },
+  { C("BuildFile"), (PyCFunction)Python_BuildFile,
+    METH_O,
+    C("Registers a new protocol buffer file in the global C++ descriptor "
+      "pool.") },
+  {NULL}
+};
+
+// --- Exposing the C proto living inside Python proto to C code:
+
+extern const Message* (*GetCProtoInsidePyProtoPtr)(PyObject* msg);
+extern Message* (*MutableCProtoInsidePyProtoPtr)(PyObject* msg);
+
+static const google::protobuf::Message* GetCProtoInsidePyProtoImpl(PyObject* msg) {
+  PyObject* c_msg_obj = PyObject_GetAttrString(msg, "_cmsg");
+  if (c_msg_obj == NULL) {
+    PyErr_Clear();
+    return NULL;
+  }
+  Py_DECREF(c_msg_obj);
+  if (!PyObject_TypeCheck(c_msg_obj, &CMessage_Type)) {
+    return NULL;
+  }
+  CMessage* c_msg = reinterpret_cast<CMessage*>(c_msg_obj);
+  return c_msg->message;
+}
+
+static google::protobuf::Message* MutableCProtoInsidePyProtoImpl(PyObject* msg) {
+  PyObject* c_msg_obj = PyObject_GetAttrString(msg, "_cmsg");
+  if (c_msg_obj == NULL) {
+    PyErr_Clear();
+    return NULL;
+  }
+  Py_DECREF(c_msg_obj);
+  if (!PyObject_TypeCheck(c_msg_obj, &CMessage_Type)) {
+    return NULL;
+  }
+  CMessage* c_msg = reinterpret_cast<CMessage*>(c_msg_obj);
+  AssureWritable(c_msg);
+  return c_msg->message;
+}
+
+// --- Module Init Function:
+
+static const char module_docstring[] =
+"python-proto2 is a module that can be used to enhance proto2 Python API\n"
+"performance.\n"
+"\n"
+"It provides access to the protocol buffers C++ reflection API that\n"
+"implements the basic protocol buffer functions.";
+
+extern "C" {
+  void init_net_proto2___python() {
+    // Initialize constants.
+    kPythonZero = PyInt_FromLong(0);
+    kint32min_py = PyInt_FromLong(kint32min);
+    kint32max_py = PyInt_FromLong(kint32max);
+    kuint32max_py = PyLong_FromLongLong(kuint32max);
+    kint64min_py = PyLong_FromLongLong(kint64min);
+    kint64max_py = PyLong_FromLongLong(kint64max);
+    kuint64max_py = PyLong_FromUnsignedLongLong(kuint64max);
+
+    global_message_factory = new DynamicMessageFactory(GetDescriptorPool());
+    global_message_factory->SetDelegateToGeneratedFactory(true);
+
+    // Export our functions to Python.
+    PyObject *m;
+    m = Py_InitModule3(C("_net_proto2___python"), methods, C(module_docstring));
+    if (m == NULL) {
+      return;
+    }
+
+    AddConstants(m);
+
+    CMessage_Type.tp_new = PyType_GenericNew;
+    if (PyType_Ready(&CMessage_Type) < 0) {
+      return;
+    }
+
+    if (!InitDescriptor()) {
+      return;
+    }
+
+    // Override {Get,Mutable}CProtoInsidePyProto.
+    GetCProtoInsidePyProtoPtr = GetCProtoInsidePyProtoImpl;
+    MutableCProtoInsidePyProtoPtr = MutableCProtoInsidePyProtoImpl;
+  }
+}
+
+}  // namespace python
+}  // namespace protobuf
+}  // namespace google
diff --git a/python/google/protobuf/pyext/python_descriptor.cc b/python/google/protobuf/pyext/python_descriptor.cc
new file mode 100644
index 00000000..fb87bad1
--- /dev/null
+++ b/python/google/protobuf/pyext/python_descriptor.cc
@@ -0,0 +1,334 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// 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.
+
+// Author: petar@google.com (Petar Petrov)
+
+#include <Python.h>
+
+#include <google/protobuf/pyext/python_descriptor.h>
+#include <google/protobuf/descriptor.pb.h>
+
+#define C(str) const_cast<char*>(str)
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+static void CFieldDescriptorDealloc(CFieldDescriptor* self);
+
+static google::protobuf::DescriptorPool* g_descriptor_pool = NULL;
+
+static PyObject* CFieldDescriptor_GetFullName(
+    CFieldDescriptor* self, void *closure) {
+  Py_XINCREF(self->full_name);
+  return self->full_name;
+}
+
+static PyObject* CFieldDescriptor_GetName(
+    CFieldDescriptor *self, void *closure) {
+  Py_XINCREF(self->name);
+  return self->name;
+}
+
+static PyObject* CFieldDescriptor_GetCppType(
+    CFieldDescriptor *self, void *closure) {
+  Py_XINCREF(self->cpp_type);
+  return self->cpp_type;
+}
+
+static PyObject* CFieldDescriptor_GetLabel(
+    CFieldDescriptor *self, void *closure) {
+  Py_XINCREF(self->label);
+  return self->label;
+}
+
+static PyObject* CFieldDescriptor_GetID(
+    CFieldDescriptor *self, void *closure) {
+  Py_XINCREF(self->id);
+  return self->id;
+}
+
+
+static PyGetSetDef CFieldDescriptorGetters[] = {
+  { C("full_name"),
+    (getter)CFieldDescriptor_GetFullName, NULL, "Full name", NULL},
+  { C("name"),
+    (getter)CFieldDescriptor_GetName, NULL, "last name", NULL},
+  { C("cpp_type"),
+    (getter)CFieldDescriptor_GetCppType, NULL, "C++ Type", NULL},
+  { C("label"),
+    (getter)CFieldDescriptor_GetLabel, NULL, "Label", NULL},
+  { C("id"),
+    (getter)CFieldDescriptor_GetID, NULL, "ID", NULL},
+  {NULL}
+};
+
+PyTypeObject CFieldDescriptor_Type = {
+  PyObject_HEAD_INIT(&PyType_Type)
+  0,
+  C("google3.net.google.protobuf.python.internal."
+    "_net_proto2___python."
+    "CFieldDescriptor"),                // tp_name
+  sizeof(CFieldDescriptor),             // tp_basicsize
+  0,                                    // tp_itemsize
+  (destructor)CFieldDescriptorDealloc,  // tp_dealloc
+  0,                                    // tp_print
+  0,                                    // tp_getattr
+  0,                                    // tp_setattr
+  0,                                    // tp_compare
+  0,                                    // tp_repr
+  0,                                    // tp_as_number
+  0,                                    // tp_as_sequence
+  0,                                    // tp_as_mapping
+  0,                                    // tp_hash
+  0,                                    // tp_call
+  0,                                    // tp_str
+  0,                                    // tp_getattro
+  0,                                    // tp_setattro
+  0,                                    // tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                   // tp_flags
+  C("A Field Descriptor"),              // tp_doc
+  0,                                    // tp_traverse
+  0,                                    // tp_clear
+  0,                                    // tp_richcompare
+  0,                                    // tp_weaklistoffset
+  0,                                    // tp_iter
+  0,                                    // tp_iternext
+  0,                                    // tp_methods
+  0,                                    // tp_members
+  CFieldDescriptorGetters,              // tp_getset
+  0,                                    // tp_base
+  0,                                    // tp_dict
+  0,                                    // tp_descr_get
+  0,                                    // tp_descr_set
+  0,                                    // tp_dictoffset
+  0,                                    // tp_init
+  PyType_GenericAlloc,                  // tp_alloc
+  PyType_GenericNew,                    // tp_new
+  PyObject_Del,                         // tp_free
+};
+
+static void CFieldDescriptorDealloc(CFieldDescriptor* self) {
+  Py_DECREF(self->full_name);
+  Py_DECREF(self->name);
+  Py_DECREF(self->cpp_type);
+  Py_DECREF(self->label);
+  Py_DECREF(self->id);
+  self->ob_type->tp_free(reinterpret_cast<PyObject*>(self));
+}
+
+typedef struct {
+  PyObject_HEAD
+
+  const google::protobuf::DescriptorPool* pool;
+} CDescriptorPool;
+
+static void CDescriptorPoolDealloc(CDescriptorPool* self);
+
+static PyObject* CDescriptorPool_NewCDescriptor(
+    const google::protobuf::FieldDescriptor* field_descriptor) {
+  CFieldDescriptor* cfield_descriptor = PyObject_New(
+      CFieldDescriptor, &CFieldDescriptor_Type);
+  if (cfield_descriptor == NULL) {
+    return NULL;
+  }
+  cfield_descriptor->descriptor = field_descriptor;
+
+  cfield_descriptor->full_name = PyString_FromString(
+      field_descriptor->full_name().c_str());
+  cfield_descriptor->name = PyString_FromString(
+      field_descriptor->name().c_str());
+  cfield_descriptor->cpp_type = PyLong_FromLong(field_descriptor->cpp_type());
+  cfield_descriptor->label = PyLong_FromLong(field_descriptor->label());
+  cfield_descriptor->id = PyLong_FromVoidPtr(cfield_descriptor);
+  return reinterpret_cast<PyObject*>(cfield_descriptor);
+}
+
+static PyObject* CDescriptorPool_FindFieldByName(
+    CDescriptorPool* self, PyObject* arg) {
+  const char* full_field_name = PyString_AsString(arg);
+  if (full_field_name == NULL) {
+    return NULL;
+  }
+
+  const google::protobuf::FieldDescriptor* field_descriptor = NULL;
+
+  field_descriptor = self->pool->FindFieldByName(full_field_name);
+  if (field_descriptor == NULL) {
+    PyErr_Format(PyExc_TypeError, "Couldn't find field %.200s",
+                 full_field_name);
+    return NULL;
+  }
+
+  return CDescriptorPool_NewCDescriptor(field_descriptor);
+}
+
+static PyObject* CDescriptorPool_FindExtensionByName(
+    CDescriptorPool* self, PyObject* arg) {
+  const char* full_field_name = PyString_AsString(arg);
+  if (full_field_name == NULL) {
+    return NULL;
+  }
+
+  const google::protobuf::FieldDescriptor* field_descriptor =
+      self->pool->FindExtensionByName(full_field_name);
+  if (field_descriptor == NULL) {
+    PyErr_Format(PyExc_TypeError, "Couldn't find field %.200s",
+                 full_field_name);
+    return NULL;
+  }
+
+  return CDescriptorPool_NewCDescriptor(field_descriptor);
+}
+
+static PyMethodDef CDescriptorPoolMethods[] = {
+  { C("FindFieldByName"),
+    (PyCFunction)CDescriptorPool_FindFieldByName,
+    METH_O,
+    C("Searches for a field descriptor by full name.") },
+  { C("FindExtensionByName"),
+    (PyCFunction)CDescriptorPool_FindExtensionByName,
+    METH_O,
+    C("Searches for extension descriptor by full name.") },
+  {NULL}
+};
+
+PyTypeObject CDescriptorPool_Type = {
+  PyObject_HEAD_INIT(&PyType_Type)
+  0,
+  C("google3.net.google.protobuf.python.internal."
+    "_net_proto2___python."
+    "CFieldDescriptor"),               // tp_name
+  sizeof(CDescriptorPool),             // tp_basicsize
+  0,                                   // tp_itemsize
+  (destructor)CDescriptorPoolDealloc,  // tp_dealloc
+  0,                                   // tp_print
+  0,                                   // tp_getattr
+  0,                                   // tp_setattr
+  0,                                   // tp_compare
+  0,                                   // tp_repr
+  0,                                   // tp_as_number
+  0,                                   // tp_as_sequence
+  0,                                   // tp_as_mapping
+  0,                                   // tp_hash
+  0,                                   // tp_call
+  0,                                   // tp_str
+  0,                                   // tp_getattro
+  0,                                   // tp_setattro
+  0,                                   // tp_as_buffer
+  Py_TPFLAGS_DEFAULT,                  // tp_flags
+  C("A Descriptor Pool"),              // tp_doc
+  0,                                   // tp_traverse
+  0,                                   // tp_clear
+  0,                                   // tp_richcompare
+  0,                                   // tp_weaklistoffset
+  0,                                   // tp_iter
+  0,                                   // tp_iternext
+  CDescriptorPoolMethods,              // tp_methods
+  0,                                   // tp_members
+  0,                                   // tp_getset
+  0,                                   // tp_base
+  0,                                   // tp_dict
+  0,                                   // tp_descr_get
+  0,                                   // tp_descr_set
+  0,                                   // tp_dictoffset
+  0,                                   // tp_init
+  PyType_GenericAlloc,                 // tp_alloc
+  PyType_GenericNew,                   // tp_new
+  PyObject_Del,                        // tp_free
+};
+
+static void CDescriptorPoolDealloc(CDescriptorPool* self) {
+  self->ob_type->tp_free(reinterpret_cast<PyObject*>(self));
+}
+
+google::protobuf::DescriptorPool* GetDescriptorPool() {
+  if (g_descriptor_pool == NULL) {
+    g_descriptor_pool = new google::protobuf::DescriptorPool(
+        google::protobuf::DescriptorPool::generated_pool());
+  }
+  return g_descriptor_pool;
+}
+
+PyObject* Python_NewCDescriptorPool(PyObject* ignored, PyObject* args) {
+  CDescriptorPool* cdescriptor_pool = PyObject_New(
+      CDescriptorPool, &CDescriptorPool_Type);
+  if (cdescriptor_pool == NULL) {
+    return NULL;
+  }
+  cdescriptor_pool->pool = GetDescriptorPool();
+  return reinterpret_cast<PyObject*>(cdescriptor_pool);
+}
+
+PyObject* Python_BuildFile(PyObject* ignored, PyObject* arg) {
+  char* message_type;
+  Py_ssize_t message_len;
+
+  if (PyString_AsStringAndSize(arg, &message_type, &message_len) < 0) {
+    return NULL;
+  }
+
+  google::protobuf::FileDescriptorProto file_proto;
+  if (!file_proto.ParseFromArray(message_type, message_len)) {
+    PyErr_SetString(PyExc_TypeError, "Couldn't parse file content!");
+    return NULL;
+  }
+
+  // If this file is already in the generated pool, don't add it again.
+  if (google::protobuf::DescriptorPool::generated_pool()->FindFileByName(
+      file_proto.name()) != NULL) {
+    Py_RETURN_NONE;
+  }
+
+  const google::protobuf::FileDescriptor* descriptor = GetDescriptorPool()->BuildFile(
+      file_proto);
+  if (descriptor == NULL) {
+    PyErr_SetString(PyExc_TypeError,
+                    "Couldn't build proto file into descriptor pool!");
+    return NULL;
+  }
+
+  Py_RETURN_NONE;
+}
+
+bool InitDescriptor() {
+  CFieldDescriptor_Type.tp_new = PyType_GenericNew;
+  if (PyType_Ready(&CFieldDescriptor_Type) < 0)
+    return false;
+
+  CDescriptorPool_Type.tp_new = PyType_GenericNew;
+  if (PyType_Ready(&CDescriptorPool_Type) < 0)
+    return false;
+  return true;
+}
+
+}  // namespace python
+}  // namespace protobuf
+}  // namespace google
diff --git a/python/google/protobuf/pyext/python_descriptor.h b/python/google/protobuf/pyext/python_descriptor.h
new file mode 100644
index 00000000..5232680f
--- /dev/null
+++ b/python/google/protobuf/pyext/python_descriptor.h
@@ -0,0 +1,87 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// 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.
+
+// Author: petar@google.com (Petar Petrov)
+
+#ifndef GOOGLE_PROTOBUF_PYTHON_DESCRIPTOR_H__
+#define GOOGLE_PROTOBUF_PYTHON_DESCRIPTOR_H__
+
+#include <Python.h>
+#include <structmember.h>
+
+#include <google/protobuf/descriptor.h>
+
+#if PY_VERSION_HEX < 0x02050000 && !defined(PY_SSIZE_T_MIN)
+typedef int Py_ssize_t;
+#define PY_SSIZE_T_MAX INT_MAX
+#define PY_SSIZE_T_MIN INT_MIN
+#endif
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+typedef struct {
+  PyObject_HEAD
+
+  // The proto2 descriptor that this object represents.
+  const google::protobuf::FieldDescriptor* descriptor;
+
+  // Full name of the field (PyString).
+  PyObject* full_name;
+
+  // Name of the field (PyString).
+  PyObject* name;
+
+  // C++ type of the field (PyLong).
+  PyObject* cpp_type;
+
+  // Name of the field (PyLong).
+  PyObject* label;
+
+  // Identity of the descriptor (PyLong used as a poiner).
+  PyObject* id;
+} CFieldDescriptor;
+
+extern PyTypeObject CFieldDescriptor_Type;
+
+extern PyTypeObject CDescriptorPool_Type;
+
+
+PyObject* Python_NewCDescriptorPool(PyObject* ignored, PyObject* args);
+PyObject* Python_BuildFile(PyObject* ignored, PyObject* args);
+bool InitDescriptor();
+google::protobuf::DescriptorPool* GetDescriptorPool();
+
+}  // namespace python
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_PYTHON_DESCRIPTOR_H__
diff --git a/python/google/protobuf/pyext/python_protobuf.cc b/python/google/protobuf/pyext/python_protobuf.cc
new file mode 100644
index 00000000..1b1ab5d1
--- /dev/null
+++ b/python/google/protobuf/pyext/python_protobuf.cc
@@ -0,0 +1,63 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// 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.
+
+// Author: qrczak@google.com (Marcin Kowalczyk)
+
+#include <google/protobuf/pyext/python_protobuf.h>
+
+namespace google {
+namespace protobuf {
+namespace python {
+
+static const Message* GetCProtoInsidePyProtoStub(PyObject* msg) {
+  return NULL;
+}
+static Message* MutableCProtoInsidePyProtoStub(PyObject* msg) {
+  return NULL;
+}
+
+// This is initialized with a default, stub implementation.
+// If python-google.protobuf.cc is loaded, the function pointer is overridden
+// with a full implementation.
+const Message* (*GetCProtoInsidePyProtoPtr)(PyObject* msg) =
+    GetCProtoInsidePyProtoStub;
+Message* (*MutableCProtoInsidePyProtoPtr)(PyObject* msg) =
+    MutableCProtoInsidePyProtoStub;
+
+const Message* GetCProtoInsidePyProto(PyObject* msg) {
+  return GetCProtoInsidePyProtoPtr(msg);
+}
+Message* MutableCProtoInsidePyProto(PyObject* msg) {
+  return MutableCProtoInsidePyProtoPtr(msg);
+}
+
+}  // namespace python
+}  // namespace protobuf
+}  // namespace google
diff --git a/python/google/protobuf/pyext/python_protobuf.h b/python/google/protobuf/pyext/python_protobuf.h
new file mode 100644
index 00000000..c5b0b1cd
--- /dev/null
+++ b/python/google/protobuf/pyext/python_protobuf.h
@@ -0,0 +1,57 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2008 Google Inc.  All rights reserved.
+// http://code.google.com/p/protobuf/
+//
+// 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.
+
+// Author: qrczak@google.com (Marcin Kowalczyk)
+//
+// This module exposes the C proto inside the given Python proto, in
+// case the Python proto is implemented with a C proto.
+
+#ifndef GOOGLE_PROTOBUF_PYTHON_PYTHON_PROTOBUF_H__
+#define GOOGLE_PROTOBUF_PYTHON_PYTHON_PROTOBUF_H__
+
+#include <Python.h>
+
+namespace google {
+namespace protobuf {
+
+class Message;
+
+namespace python {
+
+// Return the pointer to the C proto inside the given Python proto,
+// or NULL when this is not a Python proto implemented with a C proto.
+const Message* GetCProtoInsidePyProto(PyObject* msg);
+Message* MutableCProtoInsidePyProto(PyObject* msg);
+
+}  // namespace python
+}  // namespace protobuf
+
+}  // namespace google
+#endif  // GOOGLE_PROTOBUF_PYTHON_PYTHON_PROTOBUF_H__
diff --git a/python/google/protobuf/reflection.py b/python/google/protobuf/reflection.py
index 45e5ba88..1373c882 100755
--- a/python/google/protobuf/reflection.py
+++ b/python/google/protobuf/reflection.py
@@ -29,9 +29,6 @@
 # OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 # This code is meant to work on Python 2.4 and above only.
-#
-# TODO(robinson): Helpers for verbose, common checks like seeing if a
-# descriptor's cpp_type is CPPTYPE_MESSAGE.
 
 """Contains a metaclass and helper functions used to create
 protocol message classes from Descriptor objects at runtime.
@@ -50,27 +47,22 @@ this file*.
 
 __author__ = 'robinson@google.com (Will Robinson)'
 
-try:
-  from cStringIO import StringIO
-except ImportError:
-  from StringIO import StringIO
-import struct
-import weakref
 
-# We use "as" to avoid name collisions with variables.
-from google.protobuf.internal import containers
-from google.protobuf.internal import decoder
-from google.protobuf.internal import encoder
-from google.protobuf.internal import message_listener as message_listener_mod
-from google.protobuf.internal import type_checkers
-from google.protobuf.internal import wire_format
+from google.protobuf.internal import api_implementation
 from google.protobuf import descriptor as descriptor_mod
-from google.protobuf import message as message_mod
-from google.protobuf import text_format
-
 _FieldDescriptor = descriptor_mod.FieldDescriptor
 
 
+if api_implementation.Type() == 'cpp':
+  from google.protobuf.internal import cpp_message
+  _NewMessage = cpp_message.NewMessage
+  _InitMessage = cpp_message.InitMessage
+else:
+  from google.protobuf.internal import python_message
+  _NewMessage = python_message.NewMessage
+  _InitMessage = python_message.InitMessage
+
+
 class GeneratedProtocolMessageType(type):
 
   """Metaclass for protocol message classes created at runtime from Descriptors.
@@ -120,10 +112,12 @@ class GeneratedProtocolMessageType(type):
       Newly-allocated class.
     """
     descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY]
-    _AddSlots(descriptor, dictionary)
-    _AddClassAttributesForNestedExtensions(descriptor, dictionary)
+    _NewMessage(descriptor, dictionary)
     superclass = super(GeneratedProtocolMessageType, cls)
-    return superclass.__new__(cls, name, bases, dictionary)
+
+    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.
@@ -143,1018 +137,6 @@ class GeneratedProtocolMessageType(type):
         type.
     """
     descriptor = dictionary[GeneratedProtocolMessageType._DESCRIPTOR_KEY]
-
-    cls._decoders_by_tag = {}
-    cls._extensions_by_name = {}
-    cls._extensions_by_number = {}
-    if (descriptor.has_options and
-        descriptor.GetOptions().message_set_wire_format):
-      cls._decoders_by_tag[decoder.MESSAGE_SET_ITEM_TAG] = (
-          decoder.MessageSetItemDecoder(cls._extensions_by_number))
-
-    # We act as a "friend" class of the descriptor, setting
-    # its _concrete_class attribute the first time we use a
-    # given descriptor to initialize a concrete protocol message
-    # class.  We also attach stuff to each FieldDescriptor for quick
-    # lookup later on.
-    concrete_class_attr_name = '_concrete_class'
-    if not hasattr(descriptor, concrete_class_attr_name):
-      setattr(descriptor, concrete_class_attr_name, cls)
-      for field in descriptor.fields:
-        _AttachFieldHelpers(cls, field)
-
-    _AddEnumValues(descriptor, cls)
-    _AddInitMethod(descriptor, cls)
-    _AddPropertiesForFields(descriptor, cls)
-    _AddPropertiesForExtensions(descriptor, cls)
-    _AddStaticMethods(cls)
-    _AddMessageMethods(descriptor, cls)
-    _AddPrivateHelperMethods(cls)
+    _InitMessage(descriptor, cls)
     superclass = super(GeneratedProtocolMessageType, cls)
     superclass.__init__(name, bases, dictionary)
-
-
-# Stateless helpers for GeneratedProtocolMessageType below.
-# Outside clients should not access these directly.
-#
-# I opted not to make any of these methods on the metaclass, to make it more
-# clear that I'm not really using any state there and to keep clients from
-# thinking that they have direct access to these construction helpers.
-
-
-def _PropertyName(proto_field_name):
-  """Returns the name of the public property attribute which
-  clients can use to get and (in some cases) set the value
-  of a protocol message field.
-
-  Args:
-    proto_field_name: The protocol message field name, exactly
-      as it appears (or would appear) in a .proto file.
-  """
-  # TODO(robinson): Escape Python keywords (e.g., yield), and test this support.
-  # nnorwitz makes my day by writing:
-  # """
-  # FYI.  See the keyword module in the stdlib. This could be as simple as:
-  #
-  # if keyword.iskeyword(proto_field_name):
-  #   return proto_field_name + "_"
-  # return proto_field_name
-  # """
-  # Kenton says:  The above is a BAD IDEA.  People rely on being able to use
-  #   getattr() and setattr() to reflectively manipulate field values.  If we
-  #   rename the properties, then every such user has to also make sure to apply
-  #   the same transformation.  Note that currently if you name a field "yield",
-  #   you can still access it just fine using getattr/setattr -- it's not even
-  #   that cumbersome to do so.
-  # TODO(kenton):  Remove this method entirely if/when everyone agrees with my
-  #   position.
-  return proto_field_name
-
-
-def _VerifyExtensionHandle(message, extension_handle):
-  """Verify that the given extension handle is valid."""
-
-  if not isinstance(extension_handle, _FieldDescriptor):
-    raise KeyError('HasExtension() expects an extension handle, got: %s' %
-                   extension_handle)
-
-  if not extension_handle.is_extension:
-    raise KeyError('"%s" is not an extension.' % extension_handle.full_name)
-
-  if extension_handle.containing_type is not message.DESCRIPTOR:
-    raise KeyError('Extension "%s" extends message type "%s", but this '
-                   'message is of type "%s".' %
-                   (extension_handle.full_name,
-                    extension_handle.containing_type.full_name,
-                    message.DESCRIPTOR.full_name))
-
-
-def _AddSlots(message_descriptor, dictionary):
-  """Adds a __slots__ entry to dictionary, containing the names of all valid
-  attributes for this message type.
-
-  Args:
-    message_descriptor: A Descriptor instance describing this message type.
-    dictionary: Class dictionary to which we'll add a '__slots__' entry.
-  """
-  dictionary['__slots__'] = ['_cached_byte_size',
-                             '_cached_byte_size_dirty',
-                             '_fields',
-                             '_is_present_in_parent',
-                             '_listener',
-                             '_listener_for_children',
-                             '__weakref__']
-
-
-def _IsMessageSetExtension(field):
-  return (field.is_extension and
-          field.containing_type.has_options and
-          field.containing_type.GetOptions().message_set_wire_format and
-          field.type == _FieldDescriptor.TYPE_MESSAGE and
-          field.message_type == field.extension_scope and
-          field.label == _FieldDescriptor.LABEL_OPTIONAL)
-
-
-def _AttachFieldHelpers(cls, field_descriptor):
-  is_repeated = (field_descriptor.label == _FieldDescriptor.LABEL_REPEATED)
-  is_packed = (field_descriptor.has_options and
-               field_descriptor.GetOptions().packed)
-
-  if _IsMessageSetExtension(field_descriptor):
-    field_encoder = encoder.MessageSetItemEncoder(field_descriptor.number)
-    sizer = encoder.MessageSetItemSizer(field_descriptor.number)
-  else:
-    field_encoder = type_checkers.TYPE_TO_ENCODER[field_descriptor.type](
-        field_descriptor.number, is_repeated, is_packed)
-    sizer = type_checkers.TYPE_TO_SIZER[field_descriptor.type](
-        field_descriptor.number, is_repeated, is_packed)
-
-  field_descriptor._encoder = field_encoder
-  field_descriptor._sizer = sizer
-  field_descriptor._default_constructor = _DefaultValueConstructorForField(
-      field_descriptor)
-
-  def AddDecoder(wiretype, is_packed):
-    tag_bytes = encoder.TagBytes(field_descriptor.number, wiretype)
-    cls._decoders_by_tag[tag_bytes] = (
-        type_checkers.TYPE_TO_DECODER[field_descriptor.type](
-            field_descriptor.number, is_repeated, is_packed,
-            field_descriptor, field_descriptor._default_constructor))
-
-  AddDecoder(type_checkers.FIELD_TYPE_TO_WIRE_TYPE[field_descriptor.type],
-             False)
-
-  if is_repeated and wire_format.IsTypePackable(field_descriptor.type):
-    # To support wire compatibility of adding packed = true, add a decoder for
-    # packed values regardless of the field's options.
-    AddDecoder(wire_format.WIRETYPE_LENGTH_DELIMITED, True)
-
-
-def _AddClassAttributesForNestedExtensions(descriptor, dictionary):
-  extension_dict = descriptor.extensions_by_name
-  for extension_name, extension_field in extension_dict.iteritems():
-    assert extension_name not in dictionary
-    dictionary[extension_name] = extension_field
-
-
-def _AddEnumValues(descriptor, cls):
-  """Sets class-level attributes for all enum fields defined in this message.
-
-  Args:
-    descriptor: Descriptor object for this message type.
-    cls: Class we're constructing for this message type.
-  """
-  for enum_type in descriptor.enum_types:
-    for enum_value in enum_type.values:
-      setattr(cls, enum_value.name, enum_value.number)
-
-
-def _DefaultValueConstructorForField(field):
-  """Returns a function which returns a default value for a field.
-
-  Args:
-    field: FieldDescriptor object for this field.
-
-  The returned function has one argument:
-    message: Message instance containing this field, or a weakref proxy
-      of same.
-
-  That function in turn returns a default value for this field.  The default
-    value may refer back to |message| via a weak reference.
-  """
-
-  if field.label == _FieldDescriptor.LABEL_REPEATED:
-    if field.default_value != []:
-      raise ValueError('Repeated field default value not empty list: %s' % (
-          field.default_value))
-    if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-      # We can't look at _concrete_class yet since it might not have
-      # been set.  (Depends on order in which we initialize the classes).
-      message_type = field.message_type
-      def MakeRepeatedMessageDefault(message):
-        return containers.RepeatedCompositeFieldContainer(
-            message._listener_for_children, field.message_type)
-      return MakeRepeatedMessageDefault
-    else:
-      type_checker = type_checkers.GetTypeChecker(field.cpp_type, field.type)
-      def MakeRepeatedScalarDefault(message):
-        return containers.RepeatedScalarFieldContainer(
-            message._listener_for_children, type_checker)
-      return MakeRepeatedScalarDefault
-
-  if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-    # _concrete_class may not yet be initialized.
-    message_type = field.message_type
-    def MakeSubMessageDefault(message):
-      result = message_type._concrete_class()
-      result._SetListener(message._listener_for_children)
-      return result
-    return MakeSubMessageDefault
-
-  def MakeScalarDefault(message):
-    return field.default_value
-  return MakeScalarDefault
-
-
-def _AddInitMethod(message_descriptor, cls):
-  """Adds an __init__ method to cls."""
-  fields = message_descriptor.fields
-  def init(self, **kwargs):
-    self._cached_byte_size = 0
-    self._cached_byte_size_dirty = False
-    self._fields = {}
-    self._is_present_in_parent = False
-    self._listener = message_listener_mod.NullMessageListener()
-    self._listener_for_children = _Listener(self)
-    for field_name, field_value in kwargs.iteritems():
-      field = _GetFieldByName(message_descriptor, field_name)
-      if field is None:
-        raise TypeError("%s() got an unexpected keyword argument '%s'" %
-                        (message_descriptor.name, field_name))
-      if field.label == _FieldDescriptor.LABEL_REPEATED:
-        copy = field._default_constructor(self)
-        if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:  # Composite
-          for val in field_value:
-            copy.add().MergeFrom(val)
-        else:  # Scalar
-          copy.extend(field_value)
-        self._fields[field] = copy
-      elif field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-        copy = field._default_constructor(self)
-        copy.MergeFrom(field_value)
-        self._fields[field] = copy
-      else:
-        setattr(self, field_name, field_value)
-
-  init.__module__ = None
-  init.__doc__ = None
-  cls.__init__ = init
-
-
-def _GetFieldByName(message_descriptor, field_name):
-  """Returns a field descriptor by field name.
-
-  Args:
-    message_descriptor: A Descriptor describing all fields in message.
-    field_name: The name of the field to retrieve.
-  Returns:
-    The field descriptor associated with the field name.
-  """
-  try:
-    return message_descriptor.fields_by_name[field_name]
-  except KeyError:
-    raise ValueError('Protocol message has no "%s" field.' % field_name)
-
-
-def _AddPropertiesForFields(descriptor, cls):
-  """Adds properties for all fields in this protocol message type."""
-  for field in descriptor.fields:
-    _AddPropertiesForField(field, cls)
-
-  if descriptor.is_extendable:
-    # _ExtensionDict is just an adaptor with no state so we allocate a new one
-    # every time it is accessed.
-    cls.Extensions = property(lambda self: _ExtensionDict(self))
-
-
-def _AddPropertiesForField(field, cls):
-  """Adds a public property for a protocol message field.
-  Clients can use this property to get and (in the case
-  of non-repeated scalar fields) directly set the value
-  of a protocol message field.
-
-  Args:
-    field: A FieldDescriptor for this field.
-    cls: The class we're constructing.
-  """
-  # Catch it if we add other types that we should
-  # handle specially here.
-  assert _FieldDescriptor.MAX_CPPTYPE == 10
-
-  constant_name = field.name.upper() + "_FIELD_NUMBER"
-  setattr(cls, constant_name, field.number)
-
-  if field.label == _FieldDescriptor.LABEL_REPEATED:
-    _AddPropertiesForRepeatedField(field, cls)
-  elif field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-    _AddPropertiesForNonRepeatedCompositeField(field, cls)
-  else:
-    _AddPropertiesForNonRepeatedScalarField(field, cls)
-
-
-def _AddPropertiesForRepeatedField(field, cls):
-  """Adds a public property for a "repeated" protocol message field.  Clients
-  can use this property to get the value of the field, which will be either a
-  _RepeatedScalarFieldContainer or _RepeatedCompositeFieldContainer (see
-  below).
-
-  Note that when clients add values to these containers, we perform
-  type-checking in the case of repeated scalar fields, and we also set any
-  necessary "has" bits as a side-effect.
-
-  Args:
-    field: A FieldDescriptor for this field.
-    cls: The class we're constructing.
-  """
-  proto_field_name = field.name
-  property_name = _PropertyName(proto_field_name)
-
-  def getter(self):
-    field_value = self._fields.get(field)
-    if field_value is None:
-      # Construct a new object to represent this field.
-      field_value = field._default_constructor(self)
-
-      # Atomically check if another thread has preempted us and, if not, swap
-      # in the new object we just created.  If someone has preempted us, we
-      # take that object and discard ours.
-      # WARNING:  We are relying on setdefault() being atomic.  This is true
-      #   in CPython but we haven't investigated others.  This warning appears
-      #   in several other locations in this file.
-      field_value = self._fields.setdefault(field, field_value)
-    return field_value
-  getter.__module__ = None
-  getter.__doc__ = 'Getter for %s.' % proto_field_name
-
-  # We define a setter just so we can throw an exception with a more
-  # helpful error message.
-  def setter(self, new_value):
-    raise AttributeError('Assignment not allowed to repeated field '
-                         '"%s" in protocol message object.' % proto_field_name)
-
-  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
-  setattr(cls, property_name, property(getter, setter, doc=doc))
-
-
-def _AddPropertiesForNonRepeatedScalarField(field, cls):
-  """Adds a public property for a nonrepeated, scalar protocol message field.
-  Clients can use this property to get and directly set the value of the field.
-  Note that when the client sets the value of a field by using this property,
-  all necessary "has" bits are set as a side-effect, and we also perform
-  type-checking.
-
-  Args:
-    field: A FieldDescriptor for this field.
-    cls: The class we're constructing.
-  """
-  proto_field_name = field.name
-  property_name = _PropertyName(proto_field_name)
-  type_checker = type_checkers.GetTypeChecker(field.cpp_type, field.type)
-  default_value = field.default_value
-
-  def getter(self):
-    return self._fields.get(field, default_value)
-  getter.__module__ = None
-  getter.__doc__ = 'Getter for %s.' % proto_field_name
-  def setter(self, new_value):
-    type_checker.CheckValue(new_value)
-    self._fields[field] = new_value
-    # Check _cached_byte_size_dirty inline to improve performance, since scalar
-    # setters are called frequently.
-    if not self._cached_byte_size_dirty:
-      self._Modified()
-  setter.__module__ = None
-  setter.__doc__ = 'Setter for %s.' % proto_field_name
-
-  # Add a property to encapsulate the getter/setter.
-  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
-  setattr(cls, property_name, property(getter, setter, doc=doc))
-
-
-def _AddPropertiesForNonRepeatedCompositeField(field, cls):
-  """Adds a public property for a nonrepeated, composite protocol message field.
-  A composite field is a "group" or "message" field.
-
-  Clients can use this property to get the value of the field, but cannot
-  assign to the property directly.
-
-  Args:
-    field: A FieldDescriptor for this field.
-    cls: The class we're constructing.
-  """
-  # TODO(robinson): Remove duplication with similar method
-  # for non-repeated scalars.
-  proto_field_name = field.name
-  property_name = _PropertyName(proto_field_name)
-  message_type = field.message_type
-
-  def getter(self):
-    field_value = self._fields.get(field)
-    if field_value is None:
-      # Construct a new object to represent this field.
-      field_value = message_type._concrete_class()
-      field_value._SetListener(self._listener_for_children)
-
-      # Atomically check if another thread has preempted us and, if not, swap
-      # in the new object we just created.  If someone has preempted us, we
-      # take that object and discard ours.
-      # WARNING:  We are relying on setdefault() being atomic.  This is true
-      #   in CPython but we haven't investigated others.  This warning appears
-      #   in several other locations in this file.
-      field_value = self._fields.setdefault(field, field_value)
-    return field_value
-  getter.__module__ = None
-  getter.__doc__ = 'Getter for %s.' % proto_field_name
-
-  # We define a setter just so we can throw an exception with a more
-  # helpful error message.
-  def setter(self, new_value):
-    raise AttributeError('Assignment not allowed to composite field '
-                         '"%s" in protocol message object.' % proto_field_name)
-
-  # Add a property to encapsulate the getter.
-  doc = 'Magic attribute generated for "%s" proto field.' % proto_field_name
-  setattr(cls, property_name, property(getter, setter, doc=doc))
-
-
-def _AddPropertiesForExtensions(descriptor, cls):
-  """Adds properties for all fields in this protocol message type."""
-  extension_dict = descriptor.extensions_by_name
-  for extension_name, extension_field in extension_dict.iteritems():
-    constant_name = extension_name.upper() + "_FIELD_NUMBER"
-    setattr(cls, constant_name, extension_field.number)
-
-
-def _AddStaticMethods(cls):
-  # TODO(robinson): This probably needs to be thread-safe(?)
-  def RegisterExtension(extension_handle):
-    extension_handle.containing_type = cls.DESCRIPTOR
-    _AttachFieldHelpers(cls, extension_handle)
-
-    # Try to insert our extension, failing if an extension with the same number
-    # already exists.
-    actual_handle = cls._extensions_by_number.setdefault(
-        extension_handle.number, extension_handle)
-    if actual_handle is not extension_handle:
-      raise AssertionError(
-          'Extensions "%s" and "%s" both try to extend message type "%s" with '
-          'field number %d.' %
-          (extension_handle.full_name, actual_handle.full_name,
-           cls.DESCRIPTOR.full_name, extension_handle.number))
-
-    cls._extensions_by_name[extension_handle.full_name] = extension_handle
-
-    handle = extension_handle  # avoid line wrapping
-    if _IsMessageSetExtension(handle):
-      # MessageSet extension.  Also register under type name.
-      cls._extensions_by_name[
-          extension_handle.message_type.full_name] = extension_handle
-
-  cls.RegisterExtension = staticmethod(RegisterExtension)
-
-  def FromString(s):
-    message = cls()
-    message.MergeFromString(s)
-    return message
-  cls.FromString = staticmethod(FromString)
-
-
-def _IsPresent(item):
-  """Given a (FieldDescriptor, value) tuple from _fields, return true if the
-  value should be included in the list returned by ListFields()."""
-
-  if item[0].label == _FieldDescriptor.LABEL_REPEATED:
-    return bool(item[1])
-  elif item[0].cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-    return item[1]._is_present_in_parent
-  else:
-    return True
-
-
-def _AddListFieldsMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-
-  def ListFields(self):
-    all_fields = [item for item in self._fields.iteritems() if _IsPresent(item)]
-    all_fields.sort(key = lambda item: item[0].number)
-    return all_fields
-
-  cls.ListFields = ListFields
-
-
-def _AddHasFieldMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-
-  singular_fields = {}
-  for field in message_descriptor.fields:
-    if field.label != _FieldDescriptor.LABEL_REPEATED:
-      singular_fields[field.name] = field
-
-  def HasField(self, field_name):
-    try:
-      field = singular_fields[field_name]
-    except KeyError:
-      raise ValueError(
-          'Protocol message has no singular "%s" field.' % field_name)
-
-    if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-      value = self._fields.get(field)
-      return value is not None and value._is_present_in_parent
-    else:
-      return field in self._fields
-  cls.HasField = HasField
-
-
-def _AddClearFieldMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-  def ClearField(self, field_name):
-    try:
-      field = message_descriptor.fields_by_name[field_name]
-    except KeyError:
-      raise ValueError('Protocol message has no "%s" field.' % field_name)
-
-    if field in self._fields:
-      # Note:  If the field is a sub-message, its listener will still point
-      #   at us.  That's fine, because the worst than can happen is that it
-      #   will call _Modified() and invalidate our byte size.  Big deal.
-      del self._fields[field]
-
-    # Always call _Modified() -- even if nothing was changed, this is
-    # a mutating method, and thus calling it should cause the field to become
-    # present in the parent message.
-    self._Modified()
-
-  cls.ClearField = ClearField
-
-
-def _AddClearExtensionMethod(cls):
-  """Helper for _AddMessageMethods()."""
-  def ClearExtension(self, extension_handle):
-    _VerifyExtensionHandle(self, extension_handle)
-
-    # Similar to ClearField(), above.
-    if extension_handle in self._fields:
-      del self._fields[extension_handle]
-    self._Modified()
-  cls.ClearExtension = ClearExtension
-
-
-def _AddClearMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-  def Clear(self):
-    # Clear fields.
-    self._fields = {}
-    self._Modified()
-  cls.Clear = Clear
-
-
-def _AddHasExtensionMethod(cls):
-  """Helper for _AddMessageMethods()."""
-  def HasExtension(self, extension_handle):
-    _VerifyExtensionHandle(self, extension_handle)
-    if extension_handle.label == _FieldDescriptor.LABEL_REPEATED:
-      raise KeyError('"%s" is repeated.' % extension_handle.full_name)
-
-    if extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-      value = self._fields.get(extension_handle)
-      return value is not None and value._is_present_in_parent
-    else:
-      return extension_handle in self._fields
-  cls.HasExtension = HasExtension
-
-
-def _AddEqualsMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-  def __eq__(self, other):
-    if (not isinstance(other, message_mod.Message) or
-        other.DESCRIPTOR != self.DESCRIPTOR):
-      return False
-
-    if self is other:
-      return True
-
-    return self.ListFields() == other.ListFields()
-
-  cls.__eq__ = __eq__
-
-
-def _AddStrMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-  def __str__(self):
-    return text_format.MessageToString(self)
-  cls.__str__ = __str__
-
-
-def _AddSetListenerMethod(cls):
-  """Helper for _AddMessageMethods()."""
-  def SetListener(self, listener):
-    if listener is None:
-      self._listener = message_listener_mod.NullMessageListener()
-    else:
-      self._listener = listener
-  cls._SetListener = SetListener
-
-
-def _BytesForNonRepeatedElement(value, field_number, field_type):
-  """Returns the number of bytes needed to serialize a non-repeated element.
-  The returned byte count includes space for tag information and any
-  other additional space associated with serializing value.
-
-  Args:
-    value: Value we're serializing.
-    field_number: Field number of this value.  (Since the field number
-      is stored as part of a varint-encoded tag, this has an impact
-      on the total bytes required to serialize the value).
-    field_type: The type of the field.  One of the TYPE_* constants
-      within FieldDescriptor.
-  """
-  try:
-    fn = type_checkers.TYPE_TO_BYTE_SIZE_FN[field_type]
-    return fn(field_number, value)
-  except KeyError:
-    raise message_mod.EncodeError('Unrecognized field type: %d' % field_type)
-
-
-def _AddByteSizeMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-
-  def ByteSize(self):
-    if not self._cached_byte_size_dirty:
-      return self._cached_byte_size
-
-    size = 0
-    for field_descriptor, field_value in self.ListFields():
-      size += field_descriptor._sizer(field_value)
-
-    self._cached_byte_size = size
-    self._cached_byte_size_dirty = False
-    self._listener_for_children.dirty = False
-    return size
-
-  cls.ByteSize = ByteSize
-
-
-def _AddSerializeToStringMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-
-  def SerializeToString(self):
-    # Check if the message has all of its required fields set.
-    errors = []
-    if not self.IsInitialized():
-      raise message_mod.EncodeError(
-          'Message is missing required fields: ' +
-          ','.join(self.FindInitializationErrors()))
-    return self.SerializePartialToString()
-  cls.SerializeToString = SerializeToString
-
-
-def _AddSerializePartialToStringMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-
-  def SerializePartialToString(self):
-    out = StringIO()
-    self._InternalSerialize(out.write)
-    return out.getvalue()
-  cls.SerializePartialToString = SerializePartialToString
-
-  def InternalSerialize(self, write_bytes):
-    for field_descriptor, field_value in self.ListFields():
-      field_descriptor._encoder(write_bytes, field_value)
-  cls._InternalSerialize = InternalSerialize
-
-
-def _AddMergeFromStringMethod(message_descriptor, cls):
-  """Helper for _AddMessageMethods()."""
-  def MergeFromString(self, serialized):
-    length = len(serialized)
-    try:
-      if self._InternalParse(serialized, 0, length) != length:
-        # The only reason _InternalParse would return early is if it
-        # encountered an end-group tag.
-        raise message_mod.DecodeError('Unexpected end-group tag.')
-    except IndexError:
-      raise message_mod.DecodeError('Truncated message.')
-    except struct.error, e:
-      raise message_mod.DecodeError(e)
-    return length   # Return this for legacy reasons.
-  cls.MergeFromString = MergeFromString
-
-  local_ReadTag = decoder.ReadTag
-  local_SkipField = decoder.SkipField
-  decoders_by_tag = cls._decoders_by_tag
-
-  def InternalParse(self, buffer, pos, end):
-    self._Modified()
-    field_dict = self._fields
-    while pos != end:
-      (tag_bytes, new_pos) = local_ReadTag(buffer, pos)
-      field_decoder = decoders_by_tag.get(tag_bytes)
-      if field_decoder is None:
-        new_pos = local_SkipField(buffer, new_pos, end, tag_bytes)
-        if new_pos == -1:
-          return pos
-        pos = new_pos
-      else:
-        pos = field_decoder(buffer, new_pos, end, self, field_dict)
-    return pos
-  cls._InternalParse = InternalParse
-
-
-def _AddIsInitializedMethod(message_descriptor, cls):
-  """Adds the IsInitialized and FindInitializationError methods to the
-  protocol message class."""
-
-  required_fields = [field for field in message_descriptor.fields
-                           if field.label == _FieldDescriptor.LABEL_REQUIRED]
-
-  def IsInitialized(self, errors=None):
-    """Checks if all required fields of a message are set.
-
-    Args:
-      errors:  A list which, if provided, will be populated with the field
-               paths of all missing required fields.
-
-    Returns:
-      True iff the specified message has all required fields set.
-    """
-
-    # Performance is critical so we avoid HasField() and ListFields().
-
-    for field in required_fields:
-      if (field not in self._fields or
-          (field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE and
-           not self._fields[field]._is_present_in_parent)):
-        if errors is not None:
-          errors.extend(self.FindInitializationErrors())
-        return False
-
-    for field, value in self._fields.iteritems():
-      if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-        if field.label == _FieldDescriptor.LABEL_REPEATED:
-          for element in value:
-            if not element.IsInitialized():
-              if errors is not None:
-                errors.extend(self.FindInitializationErrors())
-              return False
-        elif value._is_present_in_parent and not value.IsInitialized():
-          if errors is not None:
-            errors.extend(self.FindInitializationErrors())
-          return False
-
-    return True
-
-  cls.IsInitialized = IsInitialized
-
-  def FindInitializationErrors(self):
-    """Finds required fields which are not initialized.
-
-    Returns:
-      A list of strings.  Each string is a path to an uninitialized field from
-      the top-level message, e.g. "foo.bar[5].baz".
-    """
-
-    errors = []  # simplify things
-
-    for field in required_fields:
-      if not self.HasField(field.name):
-        errors.append(field.name)
-
-    for field, value in self.ListFields():
-      if field.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-        if field.is_extension:
-          name = "(%s)" % field.full_name
-        else:
-          name = field.name
-
-        if field.label == _FieldDescriptor.LABEL_REPEATED:
-          for i in xrange(len(value)):
-            element = value[i]
-            prefix = "%s[%d]." % (name, i)
-            sub_errors = element.FindInitializationErrors()
-            errors += [ prefix + error for error in sub_errors ]
-        else:
-          prefix = name + "."
-          sub_errors = value.FindInitializationErrors()
-          errors += [ prefix + error for error in sub_errors ]
-
-    return errors
-
-  cls.FindInitializationErrors = FindInitializationErrors
-
-
-def _AddMergeFromMethod(cls):
-  LABEL_REPEATED = _FieldDescriptor.LABEL_REPEATED
-  CPPTYPE_MESSAGE = _FieldDescriptor.CPPTYPE_MESSAGE
-
-  def MergeFrom(self, msg):
-    if not isinstance(msg, cls):
-      raise TypeError(
-          "Parameter to MergeFrom() must be instance of same class.")
-
-    assert msg is not self
-    self._Modified()
-
-    fields = self._fields
-
-    for field, value in msg._fields.iteritems():
-      if field.label == LABEL_REPEATED:
-        field_value = fields.get(field)
-        if field_value is None:
-          # Construct a new object to represent this field.
-          field_value = field._default_constructor(self)
-          fields[field] = field_value
-        field_value.MergeFrom(value)
-      elif field.cpp_type == CPPTYPE_MESSAGE:
-        if value._is_present_in_parent:
-          field_value = fields.get(field)
-          if field_value is None:
-            # Construct a new object to represent this field.
-            field_value = field._default_constructor(self)
-            fields[field] = field_value
-          field_value.MergeFrom(value)
-      else:
-        self._fields[field] = value
-  cls.MergeFrom = MergeFrom
-
-
-def _AddMessageMethods(message_descriptor, cls):
-  """Adds implementations of all Message methods to cls."""
-  _AddListFieldsMethod(message_descriptor, cls)
-  _AddHasFieldMethod(message_descriptor, cls)
-  _AddClearFieldMethod(message_descriptor, cls)
-  if message_descriptor.is_extendable:
-    _AddClearExtensionMethod(cls)
-    _AddHasExtensionMethod(cls)
-  _AddClearMethod(message_descriptor, cls)
-  _AddEqualsMethod(message_descriptor, cls)
-  _AddStrMethod(message_descriptor, cls)
-  _AddSetListenerMethod(cls)
-  _AddByteSizeMethod(message_descriptor, cls)
-  _AddSerializeToStringMethod(message_descriptor, cls)
-  _AddSerializePartialToStringMethod(message_descriptor, cls)
-  _AddMergeFromStringMethod(message_descriptor, cls)
-  _AddIsInitializedMethod(message_descriptor, cls)
-  _AddMergeFromMethod(cls)
-
-
-def _AddPrivateHelperMethods(cls):
-  """Adds implementation of private helper methods to cls."""
-
-  def Modified(self):
-    """Sets the _cached_byte_size_dirty bit to true,
-    and propagates this to our listener iff this was a state change.
-    """
-
-    # Note:  Some callers check _cached_byte_size_dirty before calling
-    #   _Modified() as an extra optimization.  So, if this method is ever
-    #   changed such that it does stuff even when _cached_byte_size_dirty is
-    #   already true, the callers need to be updated.
-    if not self._cached_byte_size_dirty:
-      self._cached_byte_size_dirty = True
-      self._listener_for_children.dirty = True
-      self._is_present_in_parent = True
-      self._listener.Modified()
-
-  cls._Modified = Modified
-  cls.SetInParent = Modified
-
-
-class _Listener(object):
-
-  """MessageListener implementation that a parent message registers with its
-  child message.
-
-  In order to support semantics like:
-
-    foo.bar.baz.qux = 23
-    assert foo.HasField('bar')
-
-  ...child objects must have back references to their parents.
-  This helper class is at the heart of this support.
-  """
-
-  def __init__(self, parent_message):
-    """Args:
-      parent_message: The message whose _Modified() method we should call when
-        we receive Modified() messages.
-    """
-    # This listener establishes a back reference from a child (contained) object
-    # to its parent (containing) object.  We make this a weak reference to avoid
-    # creating cyclic garbage when the client finishes with the 'parent' object
-    # in the tree.
-    if isinstance(parent_message, weakref.ProxyType):
-      self._parent_message_weakref = parent_message
-    else:
-      self._parent_message_weakref = weakref.proxy(parent_message)
-
-    # As an optimization, we also indicate directly on the listener whether
-    # or not the parent message is dirty.  This way we can avoid traversing
-    # up the tree in the common case.
-    self.dirty = False
-
-  def Modified(self):
-    if self.dirty:
-      return
-    try:
-      # Propagate the signal to our parents iff this is the first field set.
-      self._parent_message_weakref._Modified()
-    except ReferenceError:
-      # We can get here if a client has kept a reference to a child object,
-      # and is now setting a field on it, but the child's parent has been
-      # garbage-collected.  This is not an error.
-      pass
-
-
-# TODO(robinson): Move elsewhere?  This file is getting pretty ridiculous...
-# TODO(robinson): Unify error handling of "unknown extension" crap.
-# TODO(robinson): Support iteritems()-style iteration over all
-# extensions with the "has" bits turned on?
-class _ExtensionDict(object):
-
-  """Dict-like container for supporting an indexable "Extensions"
-  field on proto instances.
-
-  Note that in all cases we expect extension handles to be
-  FieldDescriptors.
-  """
-
-  def __init__(self, extended_message):
-    """extended_message: Message instance for which we are the Extensions dict.
-    """
-
-    self._extended_message = extended_message
-
-  def __getitem__(self, extension_handle):
-    """Returns the current value of the given extension handle."""
-
-    _VerifyExtensionHandle(self._extended_message, extension_handle)
-
-    result = self._extended_message._fields.get(extension_handle)
-    if result is not None:
-      return result
-
-    if extension_handle.label == _FieldDescriptor.LABEL_REPEATED:
-      result = extension_handle._default_constructor(self._extended_message)
-    elif extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE:
-      result = extension_handle.message_type._concrete_class()
-      try:
-        result._SetListener(self._extended_message._listener_for_children)
-      except ReferenceError:
-        pass
-    else:
-      # Singular scalar -- just return the default without inserting into the
-      # dict.
-      return extension_handle.default_value
-
-    # Atomically check if another thread has preempted us and, if not, swap
-    # in the new object we just created.  If someone has preempted us, we
-    # take that object and discard ours.
-    # WARNING:  We are relying on setdefault() being atomic.  This is true
-    #   in CPython but we haven't investigated others.  This warning appears
-    #   in several other locations in this file.
-    result = self._extended_message._fields.setdefault(
-        extension_handle, result)
-
-    return result
-
-  def __eq__(self, other):
-    if not isinstance(other, self.__class__):
-      return False
-
-    my_fields = self._extended_message.ListFields()
-    other_fields = other._extended_message.ListFields()
-
-    # Get rid of non-extension fields.
-    my_fields    = [ field for field in my_fields    if field.is_extension ]
-    other_fields = [ field for field in other_fields if field.is_extension ]
-
-    return my_fields == other_fields
-
-  def __ne__(self, other):
-    return not self == other
-
-  # Note that this is only meaningful for non-repeated, scalar extension
-  # fields.  Note also that we may have to call _Modified() when we do
-  # successfully set a field this way, to set any necssary "has" bits in the
-  # ancestors of the extended message.
-  def __setitem__(self, extension_handle, value):
-    """If extension_handle specifies a non-repeated, scalar extension
-    field, sets the value of that field.
-    """
-
-    _VerifyExtensionHandle(self._extended_message, extension_handle)
-
-    if (extension_handle.label == _FieldDescriptor.LABEL_REPEATED or
-        extension_handle.cpp_type == _FieldDescriptor.CPPTYPE_MESSAGE):
-      raise TypeError(
-          'Cannot assign to extension "%s" because it is a repeated or '
-          'composite type.' % extension_handle.full_name)
-
-    # It's slightly wasteful to lookup the type checker each time,
-    # but we expect this to be a vanishingly uncommon case anyway.
-    type_checker = type_checkers.GetTypeChecker(
-        extension_handle.cpp_type, extension_handle.type)
-    type_checker.CheckValue(value)
-    self._extended_message._fields[extension_handle] = value
-    self._extended_message._Modified()
-
-  def _FindExtensionByName(self, name):
-    """Tries to find a known extension with the specified name.
-
-    Args:
-      name: Extension full name.
-
-    Returns:
-      Extension field descriptor.
-    """
-    return self._extended_message._extensions_by_name.get(name, None)
diff --git a/python/google/protobuf/text_format.py b/python/google/protobuf/text_format.py
index cc6ac902..6d77b543 100755
--- a/python/google/protobuf/text_format.py
+++ b/python/google/protobuf/text_format.py
@@ -53,24 +53,26 @@ class ParseError(Exception):
   """Thrown in case of ASCII parsing error."""
 
 
-def MessageToString(message):
+def MessageToString(message, as_utf8=False, as_one_line=False):
   out = cStringIO.StringIO()
-  PrintMessage(message, out)
+  PrintMessage(message, out, as_utf8=as_utf8, as_one_line=as_one_line)
   result = out.getvalue()
   out.close()
+  if as_one_line:
+    return result.rstrip()
   return result
 
 
-def PrintMessage(message, out, indent = 0):
+def PrintMessage(message, out, indent=0, as_utf8=False, as_one_line=False):
   for field, value in message.ListFields():
     if field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
       for element in value:
-        PrintField(field, element, out, indent)
+        PrintField(field, element, out, indent, as_utf8, as_one_line)
     else:
-      PrintField(field, value, out, indent)
+      PrintField(field, value, out, indent, as_utf8, as_one_line)
 
 
-def PrintField(field, value, out, indent = 0):
+def PrintField(field, value, out, indent=0, as_utf8=False, as_one_line=False):
   """Print a single field name/value pair.  For repeated fields, the value
   should be a single element."""
 
@@ -96,23 +98,35 @@ def PrintField(field, value, out, indent = 0):
     # don't include it.
     out.write(': ')
 
-  PrintFieldValue(field, value, out, indent)
-  out.write('\n')
+  PrintFieldValue(field, value, out, indent, as_utf8, as_one_line)
+  if as_one_line:
+    out.write(' ')
+  else:
+    out.write('\n')
 
 
-def PrintFieldValue(field, value, out, indent = 0):
+def PrintFieldValue(field, value, out, indent=0,
+                    as_utf8=False, as_one_line=False):
   """Print a single field value (not including name).  For repeated fields,
   the value should be a single element."""
 
   if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
-    out.write(' {\n')
-    PrintMessage(value, out, indent + 2)
-    out.write(' ' * indent + '}')
+    if as_one_line:
+      out.write(' { ')
+      PrintMessage(value, out, indent, as_utf8, as_one_line)
+      out.write('}')
+    else:
+      out.write(' {\n')
+      PrintMessage(value, out, indent + 2, as_utf8, as_one_line)
+      out.write(' ' * indent + '}')
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM:
     out.write(field.enum_type.values_by_number[value].name)
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
     out.write('\"')
-    out.write(_CEscape(value))
+    if type(value) is unicode:
+      out.write(_CEscape(value.encode('utf-8'), as_utf8))
+    else:
+      out.write(_CEscape(value, as_utf8))
     out.write('\"')
   elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
     if value:
@@ -334,10 +348,10 @@ class _Tokenizer(object):
     Returns:
       True iff the end was reached.
     """
-    return not self._lines and not self._current_line
+    return self.token == ''
 
   def _PopLine(self):
-    while not self._current_line:
+    while len(self._current_line) <= self._column:
       if not self._lines:
         self._current_line = ''
         return
@@ -348,11 +362,10 @@ class _Tokenizer(object):
   def _SkipWhitespace(self):
     while True:
       self._PopLine()
-      match = re.match(self._WHITESPACE, self._current_line)
+      match = self._WHITESPACE.match(self._current_line, self._column)
       if not match:
         break
       length = len(match.group(0))
-      self._current_line = self._current_line[length:]
       self._column += length
 
   def TryConsume(self, token):
@@ -402,7 +415,7 @@ class _Tokenizer(object):
       ParseError: If an identifier couldn't be consumed.
     """
     result = self.token
-    if not re.match(self._IDENTIFIER, result):
+    if not self._IDENTIFIER.match(result):
       raise self._ParseError('Expected identifier.')
     self.NextToken()
     return result
@@ -481,13 +494,13 @@ class _Tokenizer(object):
       ParseError: If a floating point number couldn't be consumed.
     """
     text = self.token
-    if re.match(self._FLOAT_INFINITY, text):
+    if self._FLOAT_INFINITY.match(text):
       self.NextToken()
       if text.startswith('-'):
         return -_INFINITY
       return _INFINITY
 
-    if re.match(self._FLOAT_NAN, text):
+    if self._FLOAT_NAN.match(text):
       self.NextToken()
       return _NAN
 
@@ -507,10 +520,10 @@ class _Tokenizer(object):
     Raises:
       ParseError: If a boolean value couldn't be consumed.
     """
-    if self.token == 'true':
+    if self.token in ('true', 't', '1'):
       self.NextToken()
       return True
-    elif self.token == 'false':
+    elif self.token in ('false', 'f', '0'):
       self.NextToken()
       return False
     else:
@@ -525,7 +538,11 @@ class _Tokenizer(object):
     Raises:
       ParseError: If a string value couldn't be consumed.
     """
-    return unicode(self.ConsumeByteString(), 'utf-8')
+    bytes = self.ConsumeByteString()
+    try:
+      return unicode(bytes, 'utf-8')
+    except UnicodeDecodeError, e:
+      raise self._StringParseError(e)
 
   def ConsumeByteString(self):
     """Consumes a byte array value.
@@ -609,7 +626,7 @@ class _Tokenizer(object):
   def _ParseError(self, message):
     """Creates and *returns* a ParseError for the current token."""
     return ParseError('%d:%d : %s' % (
-        self._line + 1, self._column + 1, message))
+        self._line + 1, self._column - len(self.token) + 1, message))
 
   def _IntegerParseError(self, e):
     return self._ParseError('Couldn\'t parse integer: ' + str(e))
@@ -617,27 +634,27 @@ class _Tokenizer(object):
   def _FloatParseError(self, e):
     return self._ParseError('Couldn\'t parse number: ' + str(e))
 
+  def _StringParseError(self, e):
+    return self._ParseError('Couldn\'t parse string: ' + str(e))
+
   def NextToken(self):
     """Reads the next meaningful token."""
     self._previous_line = self._line
     self._previous_column = self._column
-    if self.AtEnd():
-      self.token = ''
-      return
+
     self._column += len(self.token)
+    self._SkipWhitespace()
 
-    # Make sure there is data to work on.
-    self._PopLine()
+    if not self._lines and len(self._current_line) <= self._column:
+      self.token = ''
+      return
 
-    match = re.match(self._TOKEN, self._current_line)
+    match = self._TOKEN.match(self._current_line, self._column)
     if match:
       token = match.group(0)
-      self._current_line = self._current_line[len(token):]
       self.token = token
     else:
-      self.token = self._current_line[0]
-      self._current_line = self._current_line[1:]
-    self._SkipWhitespace()
+      self.token = self._current_line[self._column]
 
 
 # text.encode('string_escape') does not seem to satisfy our needs as it
@@ -645,7 +662,7 @@ class _Tokenizer(object):
 # C++ unescaping function allows hex escapes to be any length.  So,
 # "\0011".encode('string_escape') ends up being "\\x011", which will be
 # decoded in C++ as a single-character string with char code 0x11.
-def _CEscape(text):
+def _CEscape(text, as_utf8):
   def escape(c):
     o = ord(c)
     if o == 10: return r"\n"   # optional escape
@@ -656,12 +673,13 @@ def _CEscape(text):
     if o == 34: return r'\"'   # necessary escape
     if o == 92: return r"\\"   # necessary escape
 
-    if o >= 127 or o < 32: return "\\%03o" % o # necessary escapes
+    # necessary escapes
+    if not as_utf8 and (o >= 127 or o < 32): return "\\%03o" % o
     return c
   return "".join([escape(c) for c in text])
 
 
-_CUNESCAPE_HEX = re.compile('\\\\x([0-9a-fA-F]{2}|[0-9a-f-A-F])')
+_CUNESCAPE_HEX = re.compile('\\\\x([0-9a-fA-F]{2}|[0-9a-fA-F])')
 
 
 def _CUnescape(text):