Revert "Add gsutil 4.13 to telemetry/third_party"

tools/telemetry/third_party/gsutil/third_party/protorpc/protorpc/messages.py

Index: tools/telemetry/third_party/gsutil/third_party/protorpc/protorpc/messages.py
diff --git a/tools/telemetry/third_party/gsutil/third_party/protorpc/protorpc/messages.py b/tools/telemetry/third_party/gsutil/third_party/protorpc/protorpc/messages.py
deleted file mode 100644
index ca918aadd1654824fa2b6ddd76fa76439531989d..0000000000000000000000000000000000000000
--- a/tools/telemetry/third_party/gsutil/third_party/protorpc/protorpc/messages.py
+++ /dev/null
@@ -1,1929 +0,0 @@
-#!/usr/bin/env python
-#
-# Copyright 2010 Google Inc.
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-#
-
-"""Stand-alone implementation of in memory protocol messages.
-
-Public Classes:
-  Enum: Represents an enumerated type.
-  Variant: Hint for wire format to determine how to serialize.
-  Message: Base class for user defined messages.
-  IntegerField: Field for integer values.
-  FloatField: Field for float values.
-  BooleanField: Field for boolean values.
-  BytesField: Field for binary string values.
-  StringField: Field for UTF-8 string values.
-  MessageField: Field for other message type values.
-  EnumField: Field for enumerated type values.
-
-Public Exceptions (indentation indications class hierarchy):
-  EnumDefinitionError: Raised when enumeration is incorrectly defined.
-  FieldDefinitionError: Raised when field is incorrectly defined.
-    InvalidVariantError: Raised when variant is not compatible with field type.
-    InvalidDefaultError: Raised when default is not compatiable with field.
-    InvalidNumberError: Raised when field number is out of range or reserved.
-  MessageDefinitionError: Raised when message is incorrectly defined.
-    DuplicateNumberError: Raised when field has duplicate number with another.
-  ValidationError: Raised when a message or field is not valid.
-  DefinitionNotFoundError: Raised when definition not found.
-"""
-import six
-
-__author__ = 'rafek@google.com (Rafe Kaplan)'
-
-
-import types
-import weakref
-
-from . import util
-
-__all__ = ['MAX_ENUM_VALUE',
-           'MAX_FIELD_NUMBER',
-           'FIRST_RESERVED_FIELD_NUMBER',
-           'LAST_RESERVED_FIELD_NUMBER',
-
-           'Enum',
-           'Field',
-           'FieldList',
-           'Variant',
-           'Message',
-           'IntegerField',
-           'FloatField',
-           'BooleanField',
-           'BytesField',
-           'StringField',
-           'MessageField',
-           'EnumField',
-           'find_definition',
-
-           'Error',
-           'DecodeError',
-           'EncodeError',
-           'EnumDefinitionError',
-           'FieldDefinitionError',
-           'InvalidVariantError',
-           'InvalidDefaultError',
-           'InvalidNumberError',
-           'MessageDefinitionError',
-           'DuplicateNumberError',
-           'ValidationError',
-           'DefinitionNotFoundError',
-          ]
-
-
-# TODO(rafek): Add extended module test to ensure all exceptions
-# in services extends Error.
-Error = util.Error
-
-
-class EnumDefinitionError(Error):
-  """Enumeration definition error."""
-
-
-class FieldDefinitionError(Error):
-  """Field definition error."""
-
-
-class InvalidVariantError(FieldDefinitionError):
-  """Invalid variant provided to field."""
-
-
-class InvalidDefaultError(FieldDefinitionError):
-  """Invalid default provided to field."""
-
-
-class InvalidNumberError(FieldDefinitionError):
-  """Invalid number provided to field."""
-
-
-class MessageDefinitionError(Error):
-  """Message definition error."""
-
-
-class DuplicateNumberError(Error):
-  """Duplicate number assigned to field."""
-
-
-class DefinitionNotFoundError(Error):
-  """Raised when definition is not found."""
-
-
-class DecodeError(Error):
-  """Error found decoding message from encoded form."""
-
-
-class EncodeError(Error):
-  """Error found when encoding message."""
-
-
-class ValidationError(Error):
-  """Invalid value for message error."""
-
-  def __str__(self):
-    """Prints string with field name if present on exception."""
-    message = Error.__str__(self)
-    try:
-      field_name = self.field_name
-    except AttributeError:
-      return message
-    else:
-      return message
-
-
-# Attributes that are reserved by a class definition that
-# may not be used by either Enum or Message class definitions.
-_RESERVED_ATTRIBUTE_NAMES = frozenset(
-    ['__module__', '__doc__', '__qualname__'])
-
-_POST_INIT_FIELD_ATTRIBUTE_NAMES = frozenset(
-    ['name',
-     '_message_definition',
-     '_MessageField__type',
-     '_EnumField__type',
-     '_EnumField__resolved_default'])
-
-_POST_INIT_ATTRIBUTE_NAMES = frozenset(
-    ['_message_definition'])
-
-# Maximum enumeration value as defined by the protocol buffers standard.
-# All enum values must be less than or equal to this value.
-MAX_ENUM_VALUE = (2 ** 29) - 1
-
-# Maximum field number as defined by the protocol buffers standard.
-# All field numbers must be less than or equal to this value.
-MAX_FIELD_NUMBER = (2 ** 29) - 1
-
-# Field numbers between 19000 and 19999 inclusive are reserved by the
-# protobuf protocol and may not be used by fields.
-FIRST_RESERVED_FIELD_NUMBER = 19000
-LAST_RESERVED_FIELD_NUMBER = 19999
-
-
-class _DefinitionClass(type):
-  """Base meta-class used for definition meta-classes.
-
-  The Enum and Message definition classes share some basic functionality.
-  Both of these classes may be contained by a Message definition.  After
-  initialization, neither class may have attributes changed
-  except for the protected _message_definition attribute, and that attribute
-  may change only once.
-  """
-
-  __initialized = False
-
-  def __init__(cls, name, bases, dct):
-    """Constructor."""
-    type.__init__(cls, name, bases, dct)
-    # Base classes may never be initialized.
-    if cls.__bases__ != (object,):
-      cls.__initialized = True
-
-  def message_definition(cls):
-    """Get outer Message definition that contains this definition.
-
-    Returns:
-      Containing Message definition if definition is contained within one,
-      else None.
-    """
-    try:
-      return cls._message_definition()
-    except AttributeError:
-      return None
-
-  def __setattr__(cls, name, value):
-    """Overridden so that cannot set variables on definition classes after init.
-
-    Setting attributes on a class must work during the period of initialization
-    to set the enumation value class variables and build the name/number maps.
-    Once __init__ has set the __initialized flag to True prohibits setting any
-    more values on the class.  The class is in effect frozen.
-
-    Args:
-      name: Name of value to set.
-      value: Value to set.
-    """
-    if cls.__initialized and name not in _POST_INIT_ATTRIBUTE_NAMES:
-      raise AttributeError('May not change values: %s' % name)
-    else:
-      type.__setattr__(cls, name, value)
-
-  def __delattr__(cls, name):
-    """Overridden so that cannot delete varaibles on definition classes."""
-    raise TypeError('May not delete attributes on definition class')
-
-  def definition_name(cls):
-    """Helper method for creating definition name.
-
-    Names will be generated to include the classes package name, scope (if the
-    class is nested in another definition) and class name.
-
-    By default, the package name for a definition is derived from its module
-    name.  However, this value can be overriden by placing a 'package' attribute
-    in the module that contains the definition class.  For example:
-
-      package = 'some.alternate.package'
-
-      class MyMessage(Message):
-        ...
-
-      >>> MyMessage.definition_name()
-      some.alternate.package.MyMessage
-
-    Returns:
-      Dot-separated fully qualified name of definition.
-    """
-    outer_definition_name = cls.outer_definition_name()
-    if outer_definition_name is None:
-      return six.text_type(cls.__name__)
-    else:
-      return u'%s.%s' % (outer_definition_name, cls.__name__)
-
-  def outer_definition_name(cls):
-    """Helper method for creating outer definition name.
-
-    Returns:
-      If definition is nested, will return the outer definitions name, else the
-      package name.
-    """
-    outer_definition = cls.message_definition()
-    if not outer_definition:
-      return util.get_package_for_module(cls.__module__)
-    else:
-      return outer_definition.definition_name()
-
-  def definition_package(cls):
-    """Helper method for creating creating the package of a definition.
-
-    Returns:
-      Name of package that definition belongs to.
-    """
-    outer_definition = cls.message_definition()
-    if not outer_definition:
-      return util.get_package_for_module(cls.__module__)
-    else:
-      return outer_definition.definition_package()
-
-
-class _EnumClass(_DefinitionClass):
-  """Meta-class used for defining the Enum base class.
-
-  Meta-class enables very specific behavior for any defined Enum
-  class.  All attributes defined on an Enum sub-class must be integers.
-  Each attribute defined on an Enum sub-class is translated
-  into an instance of that sub-class, with the name of the attribute
-  as its name, and the number provided as its value.  It also ensures
-  that only one level of Enum class hierarchy is possible.  In other
-  words it is not possible to delcare sub-classes of sub-classes of
-  Enum.
-
-  This class also defines some functions in order to restrict the
-  behavior of the Enum class and its sub-classes.  It is not possible
-  to change the behavior of the Enum class in later classes since
-  any new classes may be defined with only integer values, and no methods.
-  """
-
-  def __init__(cls, name, bases, dct):
-    # Can only define one level of sub-classes below Enum.
-    if not (bases == (object,) or bases == (Enum,)):
-      raise EnumDefinitionError('Enum type %s may only inherit from Enum' %
-                                (name,))
-
-    cls.__by_number = {}
-    cls.__by_name = {}
-
-    # Enum base class does not need to be initialized or locked.
-    if bases != (object,):
-      # Replace integer with number.
-      for attribute, value in dct.items():
-
-        # Module will be in every enum class.
-        if attribute in _RESERVED_ATTRIBUTE_NAMES:
-          continue
-
-        # Reject anything that is not an int.
-        if not isinstance(value, six.integer_types):
-          raise EnumDefinitionError(
-              'May only use integers in Enum definitions.  Found: %s = %s' %
-              (attribute, value))
-
-        # Protocol buffer standard recommends non-negative values.
-        # Reject negative values.
-        if value < 0:
-          raise EnumDefinitionError(
-              'Must use non-negative enum values.  Found: %s = %d' %
-              (attribute, value))
-
-        if value > MAX_ENUM_VALUE:
-          raise EnumDefinitionError(
-              'Must use enum values less than or equal %d.  Found: %s = %d' %
-              (MAX_ENUM_VALUE, attribute, value))
-
-        if value in cls.__by_number:
-          raise EnumDefinitionError(
-              'Value for %s = %d is already defined: %s' %
-              (attribute, value, cls.__by_number[value].name))
-
-        # Create enum instance and list in new Enum type.
-        instance = object.__new__(cls)
-        cls.__init__(instance, attribute, value)
-        cls.__by_name[instance.name] = instance
-        cls.__by_number[instance.number] = instance
-        setattr(cls, attribute, instance)
-
-    _DefinitionClass.__init__(cls, name, bases, dct)
-
-  def __iter__(cls):
-    """Iterate over all values of enum.
-
-    Yields:
-      Enumeration instances of the Enum class in arbitrary order.
-    """
-    return iter(cls.__by_number.values())
-
-  def names(cls):
-    """Get all names for Enum.
-
-    Returns:
-      An iterator for names of the enumeration in arbitrary order.
-    """
-    return cls.__by_name.keys()
-
-  def numbers(cls):
-    """Get all numbers for Enum.
-
-    Returns:
-      An iterator for all numbers of the enumeration in arbitrary order.
-    """
-    return cls.__by_number.keys()
-
-  def lookup_by_name(cls, name):
-    """Look up Enum by name.
-
-    Args:
-      name: Name of enum to find.
-
-    Returns:
-      Enum sub-class instance of that value.
-    """
-    return cls.__by_name[name]
-
-  def lookup_by_number(cls, number):
-    """Look up Enum by number.
-
-    Args:
-      number: Number of enum to find.
-
-    Returns:
-      Enum sub-class instance of that value.
-    """
-    return cls.__by_number[number]
-
-  def __len__(cls):
-    return len(cls.__by_name)
-
-
-class Enum(six.with_metaclass(_EnumClass, object)):
-  """Base class for all enumerated types."""
-
-  __slots__ = set(('name', 'number'))
-
-  def __new__(cls, index):
-    """Acts as look-up routine after class is initialized.
-
-    The purpose of overriding __new__ is to provide a way to treat
-    Enum subclasses as casting types, similar to how the int type
-    functions.  A program can pass a string or an integer and this
-    method with "convert" that value in to an appropriate Enum instance.
-
-    Args:
-      index: Name or number to look up.  During initialization
-        this is always the name of the new enum value.
-
-    Raises:
-      TypeError: When an inappropriate index value is passed provided.
-    """
-    # If is enum type of this class, return it.
-    if isinstance(index, cls):
-      return index
-
-    # If number, look up by number.
-    if isinstance(index, six.integer_types):
-      try:
-        return cls.lookup_by_number(index)
-      except KeyError:
-        pass
-
-    # If name, look up by name.
-    if isinstance(index, six.string_types):
-      try:
-        return cls.lookup_by_name(index)
-      except KeyError:
-        pass
-
-    raise TypeError('No such value for %s in Enum %s' %
-                    (index, cls.__name__))
-
-  def __init__(self, name, number=None):
-    """Initialize new Enum instance.
-
-    Since this should only be called during class initialization any
-    calls that happen after the class is frozen raises an exception.
-    """
-    # Immediately return if __init__ was called after _Enum.__init__().
-    # It means that casting operator version of the class constructor
-    # is being used.
-    if getattr(type(self), '_DefinitionClass__initialized'):
-      return
-    object.__setattr__(self, 'name', name)
-    object.__setattr__(self, 'number', number)
-
-  def __setattr__(self, name, value):
-    raise TypeError('May not change enum values')
-
-  def __str__(self):
-    return self.name
-
-  def __int__(self):
-    return self.number
-
-  def __repr__(self):
-    return '%s(%s, %d)' % (type(self).__name__, self.name, self.number)
-
-  def __reduce__(self):
-    """Enable pickling.
-
-    Returns:
-      A 2-tuple containing the class and __new__ args to be used for restoring
-      a pickled instance.
-    """
-    return self.__class__, (self.number,)
-
-  def __cmp__(self, other):
-    """Order is by number."""
-    if isinstance(other, type(self)):
-      return cmp(self.number, other.number)
-    return NotImplemented
-
-  def __lt__(self, other):
-    """Order is by number."""
-    if isinstance(other, type(self)):
-      return self.number < other.number
-    return NotImplemented
-
-  def __le__(self, other):
-    """Order is by number."""
-    if isinstance(other, type(self)):
-      return self.number <= other.number
-    return NotImplemented
-
-  def __eq__(self, other):
-    """Order is by number."""
-    if isinstance(other, type(self)):
-      return self.number == other.number
-    return NotImplemented
-
-  def __ne__(self, other):
-    """Order is by number."""
-    if isinstance(other, type(self)):
-      return self.number != other.number
-    return NotImplemented
-
-  def __ge__(self, other):
-    """Order is by number."""
-    if isinstance(other, type(self)):
-      return self.number >= other.number
-    return NotImplemented
-
-  def __gt__(self, other):
-    """Order is by number."""
-    if isinstance(other, type(self)):
-      return self.number > other.number
-    return NotImplemented
-
-  def __hash__(self):
-    """Hash by number."""
-    return hash(self.number)
-
-  @classmethod
-  def to_dict(cls):
-    """Make dictionary version of enumerated class.
-
-    Dictionary created this way can be used with def_num.
-
-    Returns:
-      A dict (name) -> number
-    """
-    return dict((item.name, item.number) for item in iter(cls))
-
-  @staticmethod
-  def def_enum(dct, name):
-    """Define enum class from dictionary.
-
-    Args:
-      dct: Dictionary of enumerated values for type.
-      name: Name of enum.
-    """
-    return type(name, (Enum,), dct)
-
-
-# TODO(rafek): Determine to what degree this enumeration should be compatible
-# with FieldDescriptor.Type in:
-#
-#   http://code.google.com/p/protobuf/source/browse/trunk/src/google/protobuf/descriptor.proto
-class Variant(Enum):
-  """Wire format variant.
-
-  Used by the 'protobuf' wire format to determine how to transmit
-  a single piece of data.  May be used by other formats.
-
-  See: http://code.google.com/apis/protocolbuffers/docs/encoding.html
-
-  Values:
-    DOUBLE: 64-bit floating point number.
-    FLOAT: 32-bit floating point number.
-    INT64: 64-bit signed integer.
-    UINT64: 64-bit unsigned integer.
-    INT32: 32-bit signed integer.
-    BOOL: Boolean value (True or False).
-    STRING: String of UTF-8 encoded text.
-    MESSAGE: Embedded message as byte string.
-    BYTES: String of 8-bit bytes.
-    UINT32: 32-bit unsigned integer.
-    ENUM: Enum value as integer.
-    SINT32: 32-bit signed integer.  Uses "zig-zag" encoding.
-    SINT64: 64-bit signed integer.  Uses "zig-zag" encoding.
-  """
-  DOUBLE   = 1
-  FLOAT    = 2
-  INT64    = 3
-  UINT64   = 4
-  INT32    = 5
-  BOOL     = 8
-  STRING   = 9
-  MESSAGE  = 11
-  BYTES    = 12
-  UINT32   = 13
-  ENUM     = 14
-  SINT32   = 17
-  SINT64   = 18
-
-
-class _MessageClass(_DefinitionClass):
-  """Meta-class used for defining the Message base class.
-
-  For more details about Message classes, see the Message class docstring.
-  Information contained there may help understanding this class.
-
-  Meta-class enables very specific behavior for any defined Message
-  class.  All attributes defined on an Message sub-class must be field
-  instances, Enum class definitions or other Message class definitions.  Each
-  field attribute defined on an Message sub-class is added to the set of
-  field definitions and the attribute is translated in to a slot.  It also
-  ensures that only one level of Message class hierarchy is possible.  In other
-  words it is not possible to declare sub-classes of sub-classes of
-  Message.
-
-  This class also defines some functions in order to restrict the
-  behavior of the Message class and its sub-classes.  It is not possible
-  to change the behavior of the Message class in later classes since
-  any new classes may be defined with only field, Enums and Messages, and
-  no methods.
-  """
-
-  def __new__(cls, name, bases, dct):
-    """Create new Message class instance.
-
-    The __new__ method of the _MessageClass type is overridden so as to
-    allow the translation of Field instances to slots.
-    """
-    by_number = {}
-    by_name = {}
-
-    variant_map = {}
-
-    if bases != (object,):
-      # Can only define one level of sub-classes below Message.
-      if bases != (Message,):
-        raise MessageDefinitionError(
-            'Message types may only inherit from Message')
-
-      enums = []
-      messages = []
-      # Must not use iteritems because this loop will change the state of dct.
-      for key, field in dct.items():
-
-        if key in _RESERVED_ATTRIBUTE_NAMES:
-          continue
-
-        if isinstance(field, type) and issubclass(field, Enum):
-          enums.append(key)
-          continue
-
-        if (isinstance(field, type) and
-            issubclass(field, Message) and
-            field is not Message):
-          messages.append(key)
-          continue
-
-        # Reject anything that is not a field.
-        if type(field) is Field or not isinstance(field, Field):
-          raise MessageDefinitionError(
-              'May only use fields in message definitions.  Found: %s = %s' %
-              (key, field))
-
-        if field.number in by_number:
-          raise DuplicateNumberError(
-              'Field with number %d declared more than once in %s' %
-              (field.number, name))
-
-        field.name = key
-
-        # Place in name and number maps.
-        by_name[key] = field
-        by_number[field.number] = field
-
-      # Add enums if any exist.
-      if enums:
-        dct['__enums__'] = sorted(enums)
-
-      # Add messages if any exist.
-      if messages:
-        dct['__messages__'] = sorted(messages)
-
-    dct['_Message__by_number'] = by_number
-    dct['_Message__by_name'] = by_name
-
-    return _DefinitionClass.__new__(cls, name, bases, dct)
-
-  def __init__(cls, name, bases, dct):
-    """Initializer required to assign references to new class."""
-    if bases != (object,):
-      for value in dct.values():
-        if isinstance(value, _DefinitionClass) and not value is Message:
-          value._message_definition = weakref.ref(cls)
-
-      for field in cls.all_fields():
-        field._message_definition = weakref.ref(cls)
-
-    _DefinitionClass.__init__(cls, name, bases, dct)
-
-
-class Message(six.with_metaclass(_MessageClass, object)):
-  """Base class for user defined message objects.
-
-  Used to define messages for efficient transmission across network or
-  process space.  Messages are defined using the field classes (IntegerField,
-  FloatField, EnumField, etc.).
-
-  Messages are more restricted than normal classes in that they may only
-  contain field attributes and other Message and Enum definitions.  These
-  restrictions are in place because the structure of the Message class is
-  intentended to itself be transmitted across network or process space and
-  used directly by clients or even other servers.  As such methods and
-  non-field attributes could not be transmitted with the structural information
-  causing discrepancies between different languages and implementations.
-
-  Initialization and validation:
-
-    A Message object is considered to be initialized if it has all required
-    fields and any nested messages are also initialized.
-
-    Calling 'check_initialized' will raise a ValidationException if it is not
-    initialized; 'is_initialized' returns a boolean value indicating if it is
-    valid.
-
-    Validation automatically occurs when Message objects are created
-    and populated.  Validation that a given value will be compatible with
-    a field that it is assigned to can be done through the Field instances
-    validate() method.  The validate method used on a message will check that
-    all values of a message and its sub-messages are valid.  Assingning an
-    invalid value to a field will raise a ValidationException.
-
-  Example:
-
-    # Trade type.
-    class TradeType(Enum):
-      BUY = 1
-      SELL = 2
-      SHORT = 3
-      CALL = 4
-
-    class Lot(Message):
-      price = IntegerField(1, required=True)
-      quantity = IntegerField(2, required=True)
-
-    class Order(Message):
-      symbol = StringField(1, required=True)
-      total_quantity = IntegerField(2, required=True)
-      trade_type = EnumField(TradeType, 3, required=True)
-      lots = MessageField(Lot, 4, repeated=True)
-      limit = IntegerField(5)
-
-    order = Order(symbol='GOOG',
-                  total_quantity=10,
-                  trade_type=TradeType.BUY)
-
-    lot1 = Lot(price=304,
-               quantity=7)
-
-    lot2 = Lot(price = 305,
-               quantity=3)
-
-    order.lots = [lot1, lot2]
-
-    # Now object is initialized!
-    order.check_initialized()
-  """
-
-  def __init__(self, **kwargs):
-    """Initialize internal messages state.
-
-    Args:
-      A message can be initialized via the constructor by passing in keyword
-      arguments corresponding to fields.  For example:
-
-        class Date(Message):
-          day = IntegerField(1)
-          month = IntegerField(2)
-          year = IntegerField(3)
-
-      Invoking:
-
-        date = Date(day=6, month=6, year=1911)
-
-      is the same as doing:
-
-        date = Date()
-        date.day = 6
-        date.month = 6
-        date.year = 1911
-    """
-    # Tag being an essential implementation detail must be private.
-    self.__tags = {}
-    self.__unrecognized_fields = {}
-
-    assigned = set()
-    for name, value in kwargs.items():
-      setattr(self, name, value)
-      assigned.add(name)
-
-    # initialize repeated fields.
-    for field in self.all_fields():
-      if field.repeated and field.name not in assigned:
-        setattr(self, field.name, [])
-
-
-  def check_initialized(self):
-    """Check class for initialization status.
-
-    Check that all required fields are initialized
-
-    Raises:
-      ValidationError: If message is not initialized.
-    """
-    for name, field in self.__by_name.items():
-      value = getattr(self, name)
-      if value is None:
-        if field.required:
-          raise ValidationError("Message %s is missing required field %s" %
-                                (type(self).__name__, name))
-      else:
-        try:
-          if (isinstance(field, MessageField) and
-              issubclass(field.message_type, Message)):
-            if field.repeated:
-              for item in value:
-                item_message_value = field.value_to_message(item)
-                item_message_value.check_initialized()
-            else:
-              message_value = field.value_to_message(value)
-              message_value.check_initialized()
-        except ValidationError as err:
-          if not hasattr(err, 'message_name'):
-            err.message_name = type(self).__name__
-          raise
-
-  def is_initialized(self):
-    """Get initialization status.
-
-    Returns:
-      True if message is valid, else False.
-    """
-    try:
-      self.check_initialized()
-    except ValidationError:
-      return False
-    else:
-      return True
-
-  @classmethod
-  def all_fields(cls):
-    """Get all field definition objects.
-
-    Ordering is arbitrary.
-
-    Returns:
-      Iterator over all values in arbitrary order.
-    """
-    return cls.__by_name.values()
-
-  @classmethod
-  def field_by_name(cls, name):
-    """Get field by name.
-
-    Returns:
-      Field object associated with name.
-
-    Raises:
-      KeyError if no field found by that name.
-    """
-    return cls.__by_name[name]
-
-  @classmethod
-  def field_by_number(cls, number):
-    """Get field by number.
-
-    Returns:
-      Field object associated with number.
-
-    Raises:
-      KeyError if no field found by that number.
-    """
-    return cls.__by_number[number]
-
-  def get_assigned_value(self, name):
-    """Get the assigned value of an attribute.
-
-    Get the underlying value of an attribute.  If value has not been set, will
-    not return the default for the field.
-
-    Args:
-      name: Name of attribute to get.
-
-    Returns:
-      Value of attribute, None if it has not been set.
-    """
-    message_type = type(self)
-    try:
-      field = message_type.field_by_name(name)
-    except KeyError:
-      raise AttributeError('Message %s has no field %s' % (
-          message_type.__name__, name))
-    return self.__tags.get(field.number)
-
-  def reset(self, name):
-    """Reset assigned value for field.
-
-    Resetting a field will return it to its default value or None.
-
-    Args:
-      name: Name of field to reset.
-    """
-    message_type = type(self)
-    try:
-      field = message_type.field_by_name(name)
-    except KeyError:
-      if name not in message_type.__by_name:
-        raise AttributeError('Message %s has no field %s' % (
-            message_type.__name__, name))
-    if field.repeated:
-      self.__tags[field.number] = FieldList(field, [])
-    else:
-      self.__tags.pop(field.number, None)
-
-  def all_unrecognized_fields(self):
-    """Get the names of all unrecognized fields in this message."""
-    return list(self.__unrecognized_fields.keys())
-
-  def get_unrecognized_field_info(self, key, value_default=None,
-                                  variant_default=None):
-    """Get the value and variant of an unknown field in this message.
-
-    Args:
-      key: The name or number of the field to retrieve.
-      value_default: Value to be returned if the key isn't found.
-      variant_default: Value to be returned as variant if the key isn't
-        found.
-
-    Returns:
-      (value, variant), where value and variant are whatever was passed
-      to set_unrecognized_field.
-    """
-    value, variant = self.__unrecognized_fields.get(key, (value_default,
-                                                          variant_default))
-    return value, variant
-
-  def set_unrecognized_field(self, key, value, variant):
-    """Set an unrecognized field, used when decoding a message.
-
-    Args:
-      key: The name or number used to refer to this unknown value.
-      value: The value of the field.
-      variant: Type information needed to interpret the value or re-encode it.
-
-    Raises:
-      TypeError: If the variant is not an instance of messages.Variant.
-    """
-    if not isinstance(variant, Variant):
-      raise TypeError('Variant type %s is not valid.' % variant)
-    self.__unrecognized_fields[key] = value, variant
-
-  def __setattr__(self, name, value):
-    """Change set behavior for messages.
-
-    Messages may only be assigned values that are fields.
-
-    Does not try to validate field when set.
-
-    Args:
-      name: Name of field to assign to.
-      vlaue: Value to assign to field.
-
-    Raises:
-      AttributeError when trying to assign value that is not a field.
-    """
-    if name in self.__by_name or name.startswith('_Message__'):
-      object.__setattr__(self, name, value)
-    else:
-      raise AttributeError("May not assign arbitrary value %s "
-                           "to message %s" % (name, type(self).__name__))
-
-  def __repr__(self):
-    """Make string representation of message.
-
-    Example:
-
-      class MyMessage(messages.Message):
-        integer_value = messages.IntegerField(1)
-        string_value = messages.StringField(2)
-
-      my_message = MyMessage()
-      my_message.integer_value = 42
-      my_message.string_value = u'A string'
-
-      print my_message
-      >>> <MyMessage
-      ...  integer_value: 42
-      ...  string_value: u'A string'>
-
-    Returns:
-      String representation of message, including the values
-      of all fields and repr of all sub-messages.
-    """
-    body = ['<', type(self).__name__]
-    for field in sorted(self.all_fields(),
-                        key=lambda f: f.number):
-      attribute = field.name
-      value = self.get_assigned_value(field.name)
-      if value is not None:
-        body.append('\n %s: %s' % (attribute, repr(value)))
-    body.append('>')
-    return ''.join(body)
-
-  def __eq__(self, other):
-    """Equality operator.
-
-    Does field by field comparison with other message.  For
-    equality, must be same type and values of all fields must be
-    equal.
-
-    Messages not required to be initialized for comparison.
-
-    Does not attempt to determine equality for values that have
-    default values that are not set.  In other words:
-
-      class HasDefault(Message):
-
-        attr1 = StringField(1, default='default value')
-
-      message1 = HasDefault()
-      message2 = HasDefault()
-      message2.attr1 = 'default value'
-
-      message1 != message2
-
-    Does not compare unknown values.
-
-    Args:
-      other: Other message to compare with.
-    """
-    # TODO(rafek): Implement "equivalent" which does comparisons
-    # taking default values in to consideration.
-    if self is other:
-      return True
-
-    if type(self) is not type(other):
-      return False
-
-    return self.__tags == other.__tags
-
-  def __ne__(self, other):
-    """Not equals operator.
-
-    Does field by field comparison with other message.  For
-    non-equality, must be different type or any value of a field must be
-    non-equal to the same field in the other instance.
-
-    Messages not required to be initialized for comparison.
-
-    Args:
-      other: Other message to compare with.
-    """
-    return not self.__eq__(other)
-
-
-class FieldList(list):
-  """List implementation that validates field values.
-
-  This list implementation overrides all methods that add values in to a list
-  in order to validate those new elements.  Attempting to add or set list
-  values that are not of the correct type will raise ValidationError.
-  """
-
-  def __init__(self, field_instance, sequence):
-    """Constructor.
-
-    Args:
-      field_instance: Instance of field that validates the list.
-      sequence: List or tuple to construct list from.
-    """
-    if not field_instance.repeated:
-      raise FieldDefinitionError('FieldList may only accept repeated fields')
-    self.__field = field_instance
-    self.__field.validate(sequence)
-    list.__init__(self, sequence)
-
-  def __getstate__(self):
-    """Enable pickling.
-
-    The assigned field instance can't be pickled if it belongs to a Message
-    definition (message_definition uses a weakref), so the Message class and
-    field number are returned in that case.
-
-    Returns:
-      A 3-tuple containing:
-        - The field instance, or None if it belongs to a Message class.
-        - The Message class that the field instance belongs to, or None.
-        - The field instance number of the Message class it belongs to, or None.
-    """
-    message_class = self.__field.message_definition()
-    if message_class is None:
-      return self.__field, None, None
-    else:
-      return None, message_class, self.__field.number
-
-  def __setstate__(self, state):
-    """Enable unpickling.
-
-    Args:
-      state: A 3-tuple containing:
-        - The field instance, or None if it belongs to a Message class.
-        - The Message class that the field instance belongs to, or None.
-        - The field instance number of the Message class it belongs to, or None.
-    """
-    field_instance, message_class, number = state
-    if field_instance is None:
-      self.__field = message_class.field_by_number(number)
-    else:
-      self.__field = field_instance
-
-  @property
-  def field(self):
-    """Field that validates list."""
-    return self.__field
-
-  def __setslice__(self, i, j, sequence):
-    """Validate slice assignment to list."""
-    self.__field.validate(sequence)
-    list.__setslice__(self, i, j, sequence)
-
-  def __setitem__(self, index, value):
-    """Validate item assignment to list."""
-    if isinstance(index, slice):
-        self.__field.validate(value)
-    else:
-        self.__field.validate_element(value)
-    list.__setitem__(self, index, value)
-
-  def append(self, value):
-    """Validate item appending to list."""
-    self.__field.validate_element(value)
-    return list.append(self, value)
-
-  def extend(self, sequence):
-    """Validate extension of list."""
-    self.__field.validate(sequence)
-    return list.extend(self, sequence)
-
-  def insert(self, index, value):
-    """Validate item insertion to list."""
-    self.__field.validate_element(value)
-    return list.insert(self, index, value)
-
-
-# TODO(rafek): Prevent additional field subclasses.
-class Field(object):
-
-  __variant_to_type = {}
-
-  class __metaclass__(type):
-
-    def __init__(cls, name, bases, dct):
-      getattr(cls, '_Field__variant_to_type').update(
-        (variant, cls) for variant in dct.get('VARIANTS', []))
-      type.__init__(cls, name, bases, dct)
-
-  __initialized = False
-
-  @util.positional(2)
-  def __init__(self,
-               number,
-               required=False,
-               repeated=False,
-               variant=None,
-               default=None):
-    """Constructor.
-
-    The required and repeated parameters are mutually exclusive.  Setting both
-    to True will raise a FieldDefinitionError.
-
-    Sub-class Attributes:
-      Each sub-class of Field must define the following:
-        VARIANTS: Set of variant types accepted by that field.
-        DEFAULT_VARIANT: Default variant type if not specified in constructor.
-
-    Args:
-      number: Number of field.  Must be unique per message class.
-      required: Whether or not field is required.  Mutually exclusive with
-        'repeated'.
-      repeated: Whether or not field is repeated.  Mutually exclusive with
-        'required'.
-      variant: Wire-format variant hint.
-      default: Default value for field if not found in stream.
-
-    Raises:
-      InvalidVariantError when invalid variant for field is provided.
-      InvalidDefaultError when invalid default for field is provided.
-      FieldDefinitionError when invalid number provided or mutually exclusive
-        fields are used.
-      InvalidNumberError when the field number is out of range or reserved.
-    """
-    if not isinstance(number, int) or not 1 <= number <= MAX_FIELD_NUMBER:
-      raise InvalidNumberError('Invalid number for field: %s\n'
-                               'Number must be 1 or greater and %d or less' %
-                               (number, MAX_FIELD_NUMBER))
-
-    if FIRST_RESERVED_FIELD_NUMBER <= number <= LAST_RESERVED_FIELD_NUMBER:
-      raise InvalidNumberError('Tag number %d is a reserved number.\n'
-                               'Numbers %d to %d are reserved' %
-                               (number, FIRST_RESERVED_FIELD_NUMBER,
-                                LAST_RESERVED_FIELD_NUMBER))
-
-    if repeated and required:
-      raise FieldDefinitionError('Cannot set both repeated and required')
-
-    if variant is None:
-      variant = self.DEFAULT_VARIANT
-
-    if repeated and default is not None:
-      raise FieldDefinitionError('Repeated fields may not have defaults')
-
-    if variant not in self.VARIANTS:
-      raise InvalidVariantError(
-          'Invalid variant: %s\nValid variants for %s are %r' %
-          (variant, type(self).__name__, sorted(self.VARIANTS)))
-
-    self.number = number
-    self.required = required
-    self.repeated = repeated
-    self.variant = variant
-
-    if default is not None:
-      try:
-        self.validate_default(default)
-      except ValidationError as err:
-        try:
-          name = self.name
-        except AttributeError:
-          # For when raising error before name initialization.
-          raise InvalidDefaultError('Invalid default value for %s: %r: %s' %
-                                    (self.__class__.__name__, default, err))
-        else:
-          raise InvalidDefaultError('Invalid default value for field %s: '
-                                    '%r: %s' % (name, default, err))
-
-    self.__default = default
-    self.__initialized = True
-
-  def __setattr__(self, name, value):
-    """Setter overidden to prevent assignment to fields after creation.
-
-    Args:
-      name: Name of attribute to set.
-      value: Value to assign.
-    """
-    # Special case post-init names.  They need to be set after constructor.
-    if name in _POST_INIT_FIELD_ATTRIBUTE_NAMES:
-      object.__setattr__(self, name, value)
-      return
-
-    # All other attributes must be set before __initialized.
-    if not self.__initialized:
-      # Not initialized yet, allow assignment.
-      object.__setattr__(self, name, value)
-    else:
-      raise AttributeError('Field objects are read-only')
-
-  def __set__(self, message_instance, value):
-    """Set value on message.
-
-    Args:
-      message_instance: Message instance to set value on.
-      value: Value to set on message.
-    """
-    # Reaches in to message instance directly to assign to private tags.
-    if value is None:
-      if self.repeated:
-        raise ValidationError(
-          'May not assign None to repeated field %s' % self.name)
-      else:
-        message_instance._Message__tags.pop(self.number, None)
-    else:
-      if self.repeated:
-        value = FieldList(self, value)
-      else:
-        self.validate(value)
-      message_instance._Message__tags[self.number] = value
-
-  def __get__(self, message_instance, message_class):
-    if message_instance is None:
-      return self
-
-    result = message_instance._Message__tags.get(self.number)
-    if result is None:
-      return self.default
-    else:
-      return result
-
-  def validate_element(self, value):
-    """Validate single element of field.
-
-    This is different from validate in that it is used on individual
-    values of repeated fields.
-
-    Args:
-      value: Value to validate.
-
-    Raises:
-      ValidationError if value is not expected type.
-    """
-    if not isinstance(value, self.type):
-      if value is None:
-        if self.required:
-          raise ValidationError('Required field is missing')
-      else:
-        try:
-          name = self.name
-        except AttributeError:
-          raise ValidationError('Expected type %s for %s, '
-                                'found %s (type %s)' %
-                                (self.type, self.__class__.__name__,
-                                 value, type(value)))
-        else:
-          raise ValidationError('Expected type %s for field %s, '
-                                'found %s (type %s)' %
-                                (self.type, name, value, type(value)))
-
-  def __validate(self, value, validate_element):
-    """Internal validation function.
-
-    Validate an internal value using a function to validate individual elements.
-
-    Args:
-      value: Value to validate.
-      validate_element: Function to use to validate individual elements.
-
-    Raises:
-      ValidationError if value is not expected type.
-    """
-    if not self.repeated:
-      validate_element(value)
-    else:
-      # Must be a list or tuple, may not be a string.
-      if isinstance(value, (list, tuple)):
-        for element in value:
-          if element is None:
-            try:
-              name = self.name
-            except AttributeError:
-              raise ValidationError('Repeated values for %s '
-                                    'may not be None' % self.__class__.__name__)
-            else:
-              raise ValidationError('Repeated values for field %s '
-                                    'may not be None' % name)
-          validate_element(element)
-      elif value is not None:
-        try:
-          name = self.name
-        except AttributeError:
-          raise ValidationError('%s is repeated. Found: %s' % (
-            self.__class__.__name__, value))
-        else:
-          raise ValidationError('Field %s is repeated. Found: %s' % (name,
-                                                                     value))
-
-  def validate(self, value):
-    """Validate value assigned to field.
-
-    Args:
-      value: Value to validate.
-
-    Raises:
-      ValidationError if value is not expected type.
-    """
-    self.__validate(value, self.validate_element)
-
-  def validate_default_element(self, value):
-    """Validate value as assigned to field default field.
-
-    Some fields may allow for delayed resolution of default types necessary
-    in the case of circular definition references.  In this case, the default
-    value might be a place holder that is resolved when needed after all the
-    message classes are defined.
-
-    Args:
-      value: Default value to validate.
-
-    Raises:
-      ValidationError if value is not expected type.
-    """
-    self.validate_element(value)
-
-  def validate_default(self, value):
-    """Validate default value assigned to field.
-
-    Args:
-      value: Value to validate.
-
-    Raises:
-      ValidationError if value is not expected type.
-    """
-    self.__validate(value, self.validate_default_element)
-
-  def message_definition(self):
-    """Get Message definition that contains this Field definition.
-
-    Returns:
-      Containing Message definition for Field.  Will return None if for
-      some reason Field is defined outside of a Message class.
-    """
-    try:
-      return self._message_definition()
-    except AttributeError:
-      return None
-
-  @property
-  def default(self):
-    """Get default value for field."""
-    return self.__default
-
-  @classmethod
-  def lookup_field_type_by_variant(cls, variant):
-    return cls.__variant_to_type[variant]
-
-
-class IntegerField(Field):
-  """Field definition for integer values."""
-
-  VARIANTS = frozenset([Variant.INT32,
-                        Variant.INT64,
-                        Variant.UINT32,
-                        Variant.UINT64,
-                        Variant.SINT32,
-                        Variant.SINT64,
-                       ])
-
-  DEFAULT_VARIANT = Variant.INT64
-
-  type = six.integer_types
-
-
-class FloatField(Field):
-  """Field definition for float values."""
-
-  VARIANTS = frozenset([Variant.FLOAT,
-                        Variant.DOUBLE,
-                       ])
-
-  DEFAULT_VARIANT = Variant.DOUBLE
-
-  type = float
-
-
-class BooleanField(Field):
-  """Field definition for boolean values."""
-
-  VARIANTS = frozenset([Variant.BOOL])
-
-  DEFAULT_VARIANT = Variant.BOOL
-
-  type = bool
-
-
-class BytesField(Field):
-  """Field definition for byte string values."""
-
-  VARIANTS = frozenset([Variant.BYTES])
-
-  DEFAULT_VARIANT = Variant.BYTES
-
-  type = bytes
-
-
-class StringField(Field):
-  """Field definition for unicode string values."""
-
-  VARIANTS = frozenset([Variant.STRING])
-
-  DEFAULT_VARIANT = Variant.STRING
-
-  type = six.text_type
-
-  def validate_element(self, value):
-    """Validate StringField allowing for str and unicode.
-
-    Raises:
-      ValidationError if a str value is not 7-bit ascii.
-    """
-    # If value is str is it considered valid.  Satisfies "required=True".
-    if isinstance(value, bytes):
-      try:
-        six.text_type(value, 'ascii')
-      except UnicodeDecodeError as err:
-        try:
-          name = self.name
-        except AttributeError:
-          validation_error = ValidationError(
-            'Field encountered non-ASCII string %r: %s' % (value,
-                                                           err))
-        else:
-          validation_error = ValidationError(
-            'Field %s encountered non-ASCII string %r: %s' % (self.name,
-                                                              value,
-                                                              err))
-          validation_error.field_name = self.name
-        raise validation_error
-    else:
-      super(StringField, self).validate_element(value)
-
-
-class MessageField(Field):
-  """Field definition for sub-message values.
-
-  Message fields contain instance of other messages.  Instances stored
-  on messages stored on message fields  are considered to be owned by
-  the containing message instance and should not be shared between
-  owning instances.
-
-  Message fields must be defined to reference a single type of message.
-  Normally message field are defined by passing the referenced message
-  class in to the constructor.
-
-  It is possible to define a message field for a type that does not yet
-  exist by passing the name of the message in to the constructor instead
-  of a message class.  Resolution of the actual type of the message is
-  deferred until it is needed, for example, during message verification.
-  Names provided to the constructor must refer to a class within the same
-  python module as the class that is using it.  Names refer to messages
-  relative to the containing messages scope.  For example, the two fields
-  of OuterMessage refer to the same message type:
-
-    class Outer(Message):
-
-      inner_relative = MessageField('Inner', 1)
-      inner_absolute = MessageField('Outer.Inner', 2)
-
-      class Inner(Message):
-        ...
-
-  When resolving an actual type, MessageField will traverse the entire
-  scope of nested messages to match a message name.  This makes it easy
-  for siblings to reference siblings:
-
-    class Outer(Message):
-
-      class Inner(Message):
-
-        sibling = MessageField('Sibling', 1)
-
-      class Sibling(Message):
-        ...
-  """
-
-  VARIANTS = frozenset([Variant.MESSAGE])
-
-  DEFAULT_VARIANT = Variant.MESSAGE
-
-  @util.positional(3)
-  def __init__(self,
-               message_type,
-               number,
-               required=False,
-               repeated=False,
-               variant=None):
-    """Constructor.
-
-    Args:
-      message_type: Message type for field.  Must be subclass of Message.
-      number: Number of field.  Must be unique per message class.
-      required: Whether or not field is required.  Mutually exclusive to
-        'repeated'.
-      repeated: Whether or not field is repeated.  Mutually exclusive to
-        'required'.
-      variant: Wire-format variant hint.
-
-    Raises:
-      FieldDefinitionError when invalid message_type is provided.
-    """
-    valid_type = (isinstance(message_type, six.string_types) or
-                  (message_type is not Message and
-                   isinstance(message_type, type) and
-                   issubclass(message_type, Message)))
-
-    if not valid_type:
-      raise FieldDefinitionError('Invalid message class: %s' % message_type)
-
-    if isinstance(message_type, six.string_types):
-      self.__type_name = message_type
-      self.__type = None
-    else:
-      self.__type = message_type
-
-    super(MessageField, self).__init__(number,
-                                       required=required,
-                                       repeated=repeated,
-                                       variant=variant)
-
-  def __set__(self, message_instance, value):
-    """Set value on message.
-
-    Args:
-      message_instance: Message instance to set value on.
-      value: Value to set on message.
-    """
-    message_type = self.type
-    if isinstance(message_type, type) and issubclass(message_type, Message):
-      if self.repeated:
-        if value and isinstance(value, (list, tuple)):
-          value = [(message_type(**v) if isinstance(v, dict) else v)
-                   for v in value]
-      elif isinstance(value, dict):
-        value = message_type(**value)
-    super(MessageField, self).__set__(message_instance, value)
-
-  @property
-  def type(self):
-    """Message type used for field."""
-    if self.__type is None:
-      message_type = find_definition(self.__type_name, self.message_definition())
-      if not (message_type is not Message and
-              isinstance(message_type, type) and
-              issubclass(message_type, Message)):
-        raise FieldDefinitionError('Invalid message class: %s' % message_type)
-      self.__type = message_type
-    return self.__type
-
-  @property
-  def message_type(self):
-    """Underlying message type used for serialization.
-
-    Will always be a sub-class of Message.  This is different from type
-    which represents the python value that message_type is mapped to for
-    use by the user.
-    """
-    return self.type
-
-  def value_from_message(self, message):
-    """Convert a message to a value instance.
-
-    Used by deserializers to convert from underlying messages to
-    value of expected user type.
-
-    Args:
-      message: A message instance of type self.message_type.
-
-    Returns:
-      Value of self.message_type.
-    """
-    if not isinstance(message, self.message_type):
-      raise DecodeError('Expected type %s, got %s: %r' %
-                        (self.message_type.__name__,
-                         type(message).__name__,
-                         message))
-    return message
-
-  def value_to_message(self, value):
-    """Convert a value instance to a message.
-
-    Used by serializers to convert Python user types to underlying
-    messages for transmission.
-
-    Args:
-      value: A value of type self.type.
-
-    Returns:
-      An instance of type self.message_type.
-    """
-    if not isinstance(value, self.type):
-      raise EncodeError('Expected type %s, got %s: %r' %
-                        (self.type.__name__,
-                         type(value).__name__,
-                         value))
-    return value
-
-
-class EnumField(Field):
-  """Field definition for enum values.
-
-  Enum fields may have default values that are delayed until the associated enum
-  type is resolved.  This is necessary to support certain circular references.
-
-  For example:
-
-    class Message1(Message):
-
-      class Color(Enum):
-
-        RED = 1
-        GREEN = 2
-        BLUE = 3
-
-      # This field default value  will be validated when default is accessed.
-      animal = EnumField('Message2.Animal', 1, default='HORSE')
-
-    class Message2(Message):
-
-      class Animal(Enum):
-
-        DOG = 1
-        CAT = 2
-        HORSE = 3
-
-      # This fields default value will be validated right away since Color is
-      # already fully resolved.
-      color = EnumField(Message1.Color, 1, default='RED')
-  """
-
-  VARIANTS = frozenset([Variant.ENUM])
-
-  DEFAULT_VARIANT = Variant.ENUM
-
-  def __init__(self, enum_type, number, **kwargs):
-    """Constructor.
-
-    Args:
-      enum_type: Enum type for field.  Must be subclass of Enum.
-      number: Number of field.  Must be unique per message class.
-      required: Whether or not field is required.  Mutually exclusive to
-        'repeated'.
-      repeated: Whether or not field is repeated.  Mutually exclusive to
-        'required'.
-      variant: Wire-format variant hint.
-      default: Default value for field if not found in stream.
-
-    Raises:
-      FieldDefinitionError when invalid enum_type is provided.
-    """
-    valid_type = (isinstance(enum_type, six.string_types) or
-                  (enum_type is not Enum and
-                   isinstance(enum_type, type) and
-                   issubclass(enum_type, Enum)))
-
-    if not valid_type:
-      raise FieldDefinitionError('Invalid enum type: %s' % enum_type)
-
-    if isinstance(enum_type, six.string_types):
-      self.__type_name = enum_type
-      self.__type = None
-    else:
-      self.__type = enum_type
-
-    super(EnumField, self).__init__(number, **kwargs)
-
-  def validate_default_element(self, value):
-    """Validate default element of Enum field.
-
-    Enum fields allow for delayed resolution of default values when the type
-    of the field has not been resolved.  The default value of a field may be
-    a string or an integer.  If the Enum type of the field has been resolved,
-    the default value is validated against that type.
-
-    Args:
-      value: Value to validate.
-
-    Raises:
-      ValidationError if value is not expected message type.
-    """
-    if isinstance(value, (six.string_types, six.integer_types)):
-      # Validation of the value does not happen for delayed resolution
-      # enumerated types.  Ignore if type is not yet resolved.
-      if self.__type:
-        self.__type(value)
-      return
-
-    super(EnumField, self).validate_default_element(value)
-
-  @property
-  def type(self):
-    """Enum type used for field."""
-    if self.__type is None:
-      found_type = find_definition(self.__type_name, self.message_definition())
-      if not (found_type is not Enum and
-              isinstance(found_type, type) and
-              issubclass(found_type, Enum)):
-        raise FieldDefinitionError('Invalid enum type: %s' % found_type)
-
-      self.__type = found_type
-    return self.__type
-
-  @property
-  def default(self):
-    """Default for enum field.
-
-    Will cause resolution of Enum type and unresolved default value.
-    """
-    try:
-      return self.__resolved_default
-    except AttributeError:
-      resolved_default = super(EnumField, self).default
-      if isinstance(resolved_default, (six.string_types, six.integer_types)):
-        resolved_default = self.type(resolved_default)
-      self.__resolved_default = resolved_default
-      return self.__resolved_default
-
-
-@util.positional(2)
-def find_definition(name, relative_to=None, importer=__import__):
-  """Find definition by name in module-space.
-
-  The find algorthm will look for definitions by name relative to a message
-  definition or by fully qualfied name.  If no definition is found relative
-  to the relative_to parameter it will do the same search against the container
-  of relative_to.  If relative_to is a nested Message, it will search its
-  message_definition().  If that message has no message_definition() it will
-  search its module.  If relative_to is a module, it will attempt to look for
-  the containing module and search relative to it.  If the module is a top-level
-  module, it will look for the a message using a fully qualified name.  If
-  no message is found then, the search fails and DefinitionNotFoundError is
-  raised.
-
-  For example, when looking for any definition 'foo.bar.ADefinition' relative to
-  an actual message definition abc.xyz.SomeMessage:
-
-    find_definition('foo.bar.ADefinition', SomeMessage)
-
-  It is like looking for the following fully qualified names:
-
-    abc.xyz.SomeMessage. foo.bar.ADefinition
-    abc.xyz. foo.bar.ADefinition
-    abc. foo.bar.ADefinition
-    foo.bar.ADefinition
-
-  When resolving the name relative to Message definitions and modules, the
-  algorithm searches any Messages or sub-modules found in its path.
-  Non-Message values are not searched.
-
-  A name that begins with '.' is considered to be a fully qualified name.  The
-  name is always searched for from the topmost package.  For example, assume
-  two message types:
-
-    abc.xyz.SomeMessage
-    xyz.SomeMessage
-
-  Searching for '.xyz.SomeMessage' relative to 'abc' will resolve to
-  'xyz.SomeMessage' and not 'abc.xyz.SomeMessage'.  For this kind of name,
-  the relative_to parameter is effectively ignored and always set to None.
-
-  For more information about package name resolution, please see:
-
-    http://code.google.com/apis/protocolbuffers/docs/proto.html#packages
-
-  Args:
-    name: Name of definition to find.  May be fully qualified or relative name.
-    relative_to: Search for definition relative to message definition or module.
-      None will cause a fully qualified name search.
-    importer: Import function to use for resolving modules.
-
-  Returns:
-    Enum or Message class definition associated with name.
-
-  Raises:
-    DefinitionNotFoundError if no definition is found in any search path.
-  """
-  # Check parameters.
-  if not (relative_to is None or
-          isinstance(relative_to, types.ModuleType) or
-          isinstance(relative_to, type) and issubclass(relative_to, Message)):
-    raise TypeError('relative_to must be None, Message definition or module.  '
-                    'Found: %s' % relative_to)
-
-  name_path = name.split('.')
-
-  # Handle absolute path reference.
-  if not name_path[0]:
-    relative_to = None
-    name_path = name_path[1:]
-
-  def search_path():
-    """Performs a single iteration searching the path from relative_to.
-
-    This is the function that searches up the path from a relative object.
-
-      fully.qualified.object . relative.or.nested.Definition
-                               ---------------------------->
-                                                  ^
-                                                  |
-                            this part of search --+
-
-    Returns:
-      Message or Enum at the end of name_path, else None.
-    """
-    next = relative_to
-    for node in name_path:
-      # Look for attribute first.
-      attribute = getattr(next, node, None)
-
-      if attribute is not None:
-        next = attribute
-      else:
-        # If module, look for sub-module.
-        if next is None or isinstance(next, types.ModuleType):
-          if next is None:
-            module_name = node
-          else:
-            module_name = '%s.%s' % (next.__name__, node)
-
-          try:
-            fromitem = module_name.split('.')[-1]
-            next = importer(module_name, '', '', [str(fromitem)])
-          except ImportError:
-            return None
-        else:
-          return None
-
-      if (not isinstance(next, types.ModuleType) and
-          not (isinstance(next, type) and
-               issubclass(next, (Message, Enum)))):
-        return None
-
-    return next
-
-  while True:
-    found = search_path()
-    if isinstance(found, type) and issubclass(found, (Enum, Message)):
-      return found
-    else:
-      # Find next relative_to to search against.
-      #
-      #   fully.qualified.object . relative.or.nested.Definition
-      #   <---------------------
-      #           ^
-      #           |
-      #   does this part of search
-      if relative_to is None:
-        # Fully qualified search was done.  Nothing found.  Fail.
-        raise DefinitionNotFoundError('Could not find definition for %s'
-                                      % (name,))
-      else:
-        if isinstance(relative_to, types.ModuleType):
-          # Find parent module.
-          module_path = relative_to.__name__.split('.')[:-1]
-          if not module_path:
-            relative_to = None
-          else:
-            # Should not raise ImportError.  If it does... weird and
-            # unexepected.  Propagate.
-            relative_to = importer(
-              '.'.join(module_path), '', '', [module_path[-1]])
-        elif (isinstance(relative_to, type) and
-              issubclass(relative_to, Message)):
-          parent = relative_to.message_definition()
-          if parent is None:
-            last_module_name = relative_to.__module__.split('.')[-1]
-            relative_to = importer(
-              relative_to.__module__, '', '', [last_module_name])
-          else:
-            relative_to = parent