Python google.protobuf.descriptor.FieldDescriptor() Examples

def _InternalAddFileDescriptor(self, file_desc):
    """Adds a FileDescriptor to the pool, non-recursively.

    If the FileDescriptor contains messages or enums, the caller must explicitly
    register them.

    Args:
      file_desc: A FileDescriptor.
    """

    self._AddFileDescriptor(file_desc)
    # TODO(jieluo): This is a temporary solution for FieldDescriptor.file.
    # FieldDescriptor.file is added in code gen. Remove this solution after
    # maybe 2020 for compatibility reason (with 3.4.1 only).
    for extension in file_desc.extensions_by_name.values():
      self._file_desc_by_toplevel_extension[
          extension.full_name] = file_desc 

def FindAllExtensions(self, message_descriptor):
    """Gets all the known extension of a given message.

    Extensions have to be registered to this pool by calling
    AddExtensionDescriptor.

    Args:
      message_descriptor: descriptor of the extended message.

    Returns:
      A list of FieldDescriptor describing the extensions.
    """
    # Fallback to descriptor db if FindAllExtensionNumbers is provided.
    if self._descriptor_db and hasattr(
        self._descriptor_db, 'FindAllExtensionNumbers'):
      full_name = message_descriptor.full_name
      all_numbers = self._descriptor_db.FindAllExtensionNumbers(full_name)
      for number in all_numbers:
        if number in self._extensions_by_number[message_descriptor]:
          continue
        self._TryLoadExtensionFromDB(message_descriptor, number)

    return list(self._extensions_by_number[message_descriptor].values()) 

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 FindExtensionByName(self, full_name):
    """Loads the named extension descriptor from the pool.

    Args:
      full_name: The full name of the extension descriptor to load.

    Returns:
      A FieldDescriptor, describing the named extension.
    """
    full_name = _NormalizeFullyQualifiedName(full_name)
    message_name, _, extension_name = full_name.rpartition('.')
    try:
      # Most extensions are nested inside a message.
      scope = self.FindMessageTypeByName(message_name)
    except KeyError:
      # Some extensions are defined at file scope.
      scope = self.FindFileContainingSymbol(full_name)
    return scope.extensions_by_name[extension_name] 

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 _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 AddFileDescriptor(self, file_desc):
    """Adds a FileDescriptor to the pool, non-recursively.

    If the FileDescriptor contains messages or enums, the caller must explicitly
    register them.

    Args:
      file_desc: A FileDescriptor.
    """

    self._AddFileDescriptor(file_desc)
    # TODO(jieluo): This is a temporary solution for FieldDescriptor.file.
    # Remove it when FieldDescriptor.file is added in code gen.
    for extension in file_desc.extensions_by_name.values():
      self._file_desc_by_toplevel_extension[
          extension.full_name] = file_desc 

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 _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 _CheckConflictRegister(self, desc):
    """Check if the descriptor name conflicts with another of the same name.

    Args:
      desc: Descriptor of a message, enum, service or extension.
    """
    desc_name = desc.full_name
    for register, descriptor_type in [
        (self._descriptors, descriptor.Descriptor),
        (self._enum_descriptors, descriptor.EnumDescriptor),
        (self._service_descriptors, descriptor.ServiceDescriptor),
        (self._toplevel_extensions, descriptor.FieldDescriptor)]:
      if desc_name in register:
        file_name = register[desc_name].file.name
        if not isinstance(desc, descriptor_type) or (
            file_name != desc.file.name):
          warn_msg = ('Conflict register for file "' + desc.file.name +
                      '": ' + desc_name +
                      ' is already defined in file "' +
                      file_name + '"')
          warnings.warn(warn_msg, RuntimeWarning)
        return 

def AddFileDescriptor(self, file_desc):
    """Adds a FileDescriptor to the pool, non-recursively.

    If the FileDescriptor contains messages or enums, the caller must explicitly
    register them.

    Args:
      file_desc: A FileDescriptor.
    """

    self._AddFileDescriptor(file_desc)
    # TODO(jieluo): This is a temporary solution for FieldDescriptor.file.
    # FieldDescriptor.file is added in code gen. Remove this solution after
    # maybe 2020 for compatibility reason (with 3.4.1 only).
    for extension in file_desc.extensions_by_name.values():
      self._file_desc_by_toplevel_extension[
          extension.full_name] = file_desc 

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 FindExtensionByName(self, full_name):
    """Loads the named extension descriptor from the pool.

    Args:
      full_name: The full name of the extension descriptor to load.

    Returns:
      A FieldDescriptor, describing the named extension.
    """
    full_name = _NormalizeFullyQualifiedName(full_name)
    message_name, _, extension_name = full_name.rpartition('.')
    try:
      # Most extensions are nested inside a message.
      scope = self.FindMessageTypeByName(message_name)
    except KeyError:
      # Some extensions are defined at file scope.
      scope = self.FindFileContainingSymbol(full_name)
    return scope.extensions_by_name[extension_name] 

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 _InternalAddFileDescriptor(self, file_desc):
    """Adds a FileDescriptor to the pool, non-recursively.

    If the FileDescriptor contains messages or enums, the caller must explicitly
    register them.

    Args:
      file_desc: A FileDescriptor.
    """

    self._AddFileDescriptor(file_desc)
    # TODO(jieluo): This is a temporary solution for FieldDescriptor.file.
    # FieldDescriptor.file is added in code gen. Remove this solution after
    # maybe 2020 for compatibility reason (with 3.4.1 only).
    for extension in file_desc.extensions_by_name.values():
      self._file_desc_by_toplevel_extension[
          extension.full_name] = file_desc 

def FindAllExtensions(self, message_descriptor):
    """Gets all the known extension of a given message.

    Extensions have to be registered to this pool by calling
    AddExtensionDescriptor.

    Args:
      message_descriptor: descriptor of the extended message.

    Returns:
      A list of FieldDescriptor describing the extensions.
    """
    # Fallback to descriptor db if FindAllExtensionNumbers is provided.
    if self._descriptor_db and hasattr(
        self._descriptor_db, 'FindAllExtensionNumbers'):
      full_name = message_descriptor.full_name
      all_numbers = self._descriptor_db.FindAllExtensionNumbers(full_name)
      for number in all_numbers:
        if number in self._extensions_by_number[message_descriptor]:
          continue
        self._TryLoadExtensionFromDB(message_descriptor, number)

    return list(self._extensions_by_number[message_descriptor].values()) 

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 == descriptor.FieldDescriptor.TYPE_MESSAGE and
          field.label == descriptor.FieldDescriptor.LABEL_OPTIONAL) 

def _CheckConflictRegister(self, desc, desc_name, file_name):
    """Check if the descriptor name conflicts with another of the same name.

    Args:
      desc: Descriptor of a message, enum, service, extension or enum value.
      desc_name: the full name of desc.
      file_name: The file name of descriptor.
    """
    for register, descriptor_type in [
        (self._descriptors, descriptor.Descriptor),
        (self._enum_descriptors, descriptor.EnumDescriptor),
        (self._service_descriptors, descriptor.ServiceDescriptor),
        (self._toplevel_extensions, descriptor.FieldDescriptor),
        (self._top_enum_values, descriptor.EnumValueDescriptor)]:
      if desc_name in register:
        old_desc = register[desc_name]
        if isinstance(old_desc, descriptor.EnumValueDescriptor):
          old_file = old_desc.type.file.name
        else:
          old_file = old_desc.file.name

        if not isinstance(desc, descriptor_type) or (
            old_file != file_name):
          error_msg = ('Conflict register for file "' + file_name +
                       '": ' + desc_name +
                       ' is already defined in file "' +
                       old_file + '". Please fix the conflict by adding '
                       'package name on the proto file, or use different '
                       'name for the duplication.')
          if isinstance(desc, descriptor.EnumValueDescriptor):
            error_msg += ('\nNote: enum values appear as '
                          'siblings of the enum type instead of '
                          'children of it.')

          raise TypeError(error_msg)

        return 

def _AddExtensionDescriptor(self, extension):
    """Adds a FieldDescriptor describing an extension to the pool.

    Args:
      extension: A FieldDescriptor.

    Raises:
      AssertionError: when another extension with the same number extends the
        same message.
      TypeError: when the specified extension is not a
        descriptor.FieldDescriptor.
    """
    if not (isinstance(extension, descriptor.FieldDescriptor) and
            extension.is_extension):
      raise TypeError('Expected an extension descriptor.')

    if extension.extension_scope is None:
      self._toplevel_extensions[extension.full_name] = extension

    try:
      existing_desc = self._extensions_by_number[
          extension.containing_type][extension.number]
    except KeyError:
      pass
    else:
      if extension is not existing_desc:
        raise AssertionError(
            'Extensions "%s" and "%s" both try to extend message type "%s" '
            'with field number %d.' %
            (extension.full_name, existing_desc.full_name,
             extension.containing_type.full_name, extension.number))

    self._extensions_by_number[extension.containing_type][
        extension.number] = extension
    self._extensions_by_name[extension.containing_type][
        extension.full_name] = extension

    # Also register MessageSet extensions with the type name.
    if _IsMessageSetExtension(extension):
      self._extensions_by_name[extension.containing_type][
          extension.message_type.full_name] = extension 

def FindExtensionByName(self, full_name):
    """Loads the named extension descriptor from the pool.

    Args:
      full_name: The full name of the extension descriptor to load.

    Returns:
      A FieldDescriptor, describing the named extension.

    Raises:
      KeyError: if the extension cannot be found in the pool.
    """
    full_name = _NormalizeFullyQualifiedName(full_name)
    try:
      # The proto compiler does not give any link between the FileDescriptor
      # and top-level extensions unless the FileDescriptorProto is added to
      # the DescriptorDatabase, but this can impact memory usage.
      # So we registered these extensions by name explicitly.
      return self._toplevel_extensions[full_name]
    except KeyError:
      pass
    message_name, _, extension_name = full_name.rpartition('.')
    try:
      # Most extensions are nested inside a message.
      scope = self.FindMessageTypeByName(message_name)
    except KeyError:
      # Some extensions are defined at file scope.
      scope = self._FindFileContainingSymbolInDb(full_name)
    return scope.extensions_by_name[extension_name] 

def testHandWrittenReflection(self):
    # 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',
        index=0, number=1, type=FieldDescriptor.TYPE_INT64,
        cpp_type=FieldDescriptor.CPPTYPE_INT64,
        label=FieldDescriptor.LABEL_OPTIONAL, default_value=0,
        containing_type=None, message_type=None, enum_type=None,
        is_extension=False, extension_scope=None,
        options=descriptor_pb2.FieldOptions())
    mydescriptor = descriptor.Descriptor(
        name='MyProto', full_name='MyProto', filename='ignored',
        containing_type=None, nested_types=[], enum_types=[],
        fields=[foo_field_descriptor], extensions=[],
        options=descriptor_pb2.MessageOptions())
    class MyProtoClass(six.with_metaclass(reflection.GeneratedProtocolMessageType, message.Message)):
      DESCRIPTOR = mydescriptor
    myproto_instance = MyProtoClass()
    self.assertEqual(0, myproto_instance.foo_field)
    self.assertTrue(not myproto_instance.HasField('foo_field'))
    myproto_instance.foo_field = 23
    self.assertEqual(23, myproto_instance.foo_field)
    self.assertTrue(myproto_instance.HasField('foo_field')) 

def testPackedOptions(self):
    proto = unittest_pb2.TestAllTypes()
    proto.optional_int32 = 1
    proto.optional_double = 3.0
    for field_descriptor, _ in proto.ListFields():
      self.assertEqual(False, field_descriptor.GetOptions().packed)

    proto = unittest_pb2.TestPackedTypes()
    proto.packed_int32.append(1)
    proto.packed_double.append(3.0)
    for field_descriptor, _ in proto.ListFields():
      self.assertEqual(True, field_descriptor.GetOptions().packed)
      self.assertEqual(descriptor.FieldDescriptor.LABEL_REPEATED,
                       field_descriptor.label) 

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 GetTypeChecker(field):
  """Returns a type checker for a message field of the specified types.

  Args:
    field: FieldDescriptor object for this field.

  Returns:
    An instance of TypeChecker which can be used to verify the types
    of values assigned to a field of the specified type.
  """
  if (field.cpp_type == _FieldDescriptor.CPPTYPE_STRING and
      field.type == _FieldDescriptor.TYPE_STRING):
    return UnicodeValueChecker()
  if field.cpp_type == _FieldDescriptor.CPPTYPE_ENUM:
    if SupportsOpenEnums(field):
      # When open enums are supported, any int32 can be assigned.
      return _VALUE_CHECKERS[_FieldDescriptor.CPPTYPE_INT32]
    else:
      return EnumValueChecker(field.enum_type)
  return _VALUE_CHECKERS[field.cpp_type]


# None of the typecheckers below make any attempt to guard against people
# subclassing builtin types and doing weird things.  We're not trying to
# protect against malicious clients here, just people accidentally shooting
# themselves in the foot in obvious ways. 

def _MakeFieldDescriptor(self, field_proto, message_name, index,
                           is_extension=False):
    """Creates a field descriptor from a FieldDescriptorProto.

    For message and enum type fields, this method will do a look up
    in the pool for the appropriate descriptor for that type. If it
    is unavailable, it will fall back to the _source function to
    create it. If this type is still unavailable, construction will
    fail.

    Args:
      field_proto: The proto describing the field.
      message_name: The name of the containing message.
      index: Index of the field
      is_extension: Indication that this field is for an extension.

    Returns:
      An initialized FieldDescriptor object
    """

    if message_name:
      full_name = '.'.join((message_name, field_proto.name))
    else:
      full_name = field_proto.name

    return descriptor.FieldDescriptor(
        name=field_proto.name,
        full_name=full_name,
        index=index,
        number=field_proto.number,
        type=field_proto.type,
        cpp_type=None,
        message_type=None,
        enum_type=None,
        containing_type=None,
        label=field_proto.label,
        has_default_value=False,
        default_value=None,
        is_extension=is_extension,
        extension_scope=None,
        options=field_proto.options) 

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 GetTypeChecker(field):
  """Returns a type checker for a message field of the specified types.

  Args:
    field: FieldDescriptor object for this field.

  Returns:
    An instance of TypeChecker which can be used to verify the types
    of values assigned to a field of the specified type.
  """
  if (field.cpp_type == _FieldDescriptor.CPPTYPE_STRING and
      field.type == _FieldDescriptor.TYPE_STRING):
    return UnicodeValueChecker()
  if field.cpp_type == _FieldDescriptor.CPPTYPE_ENUM:
    if SupportsOpenEnums(field):
      # When open enums are supported, any int32 can be assigned.
      return _VALUE_CHECKERS[_FieldDescriptor.CPPTYPE_INT32]
    else:
      return EnumValueChecker(field.enum_type)
  return _VALUE_CHECKERS[field.cpp_type]


# None of the typecheckers below make any attempt to guard against people
# subclassing builtin types and doing weird things.  We're not trying to
# protect against malicious clients here, just people accidentally shooting
# themselves in the foot in obvious ways. 

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 == descriptor.FieldDescriptor.TYPE_MESSAGE and
          field.label == descriptor.FieldDescriptor.LABEL_OPTIONAL) 

def __init__(self, descriptor_db=None):
    """Initializes a Pool of proto buffs.

    The descriptor_db argument to the constructor is provided to allow
    specialized file descriptor proto lookup code to be triggered on demand. An
    example would be an implementation which will read and compile a file
    specified in a call to FindFileByName() and not require the call to Add()
    at all. Results from this database will be cached internally here as well.

    Args:
      descriptor_db: A secondary source of file descriptors.
    """

    self._internal_db = descriptor_database.DescriptorDatabase()
    self._descriptor_db = descriptor_db
    self._descriptors = {}
    self._enum_descriptors = {}
    self._service_descriptors = {}
    self._file_descriptors = {}
    self._toplevel_extensions = {}
    # TODO(jieluo): Remove _file_desc_by_toplevel_extension when
    # FieldDescriptor.file is added in code gen.
    self._file_desc_by_toplevel_extension = {}
    # We store extensions in two two-level mappings: The first key is the
    # descriptor of the message being extended, the second key is the extension
    # full name or its tag number.
    self._extensions_by_name = collections.defaultdict(dict)
    self._extensions_by_number = collections.defaultdict(dict) 

def AddExtensionDescriptor(self, extension):
    """Adds a FieldDescriptor describing an extension to the pool.

    Args:
      extension: A FieldDescriptor.

    Raises:
      AssertionError: when another extension with the same number extends the
        same message.
      TypeError: when the specified extension is not a
        descriptor.FieldDescriptor.
    """
    if not (isinstance(extension, descriptor.FieldDescriptor) and
            extension.is_extension):
      raise TypeError('Expected an extension descriptor.')

    if extension.extension_scope is None:
      self._toplevel_extensions[extension.full_name] = extension

    try:
      existing_desc = self._extensions_by_number[
          extension.containing_type][extension.number]
    except KeyError:
      pass
    else:
      if extension is not existing_desc:
        raise AssertionError(
            'Extensions "%s" and "%s" both try to extend message type "%s" '
            'with field number %d.' %
            (extension.full_name, existing_desc.full_name,
             extension.containing_type.full_name, extension.number))

    self._extensions_by_number[extension.containing_type][
        extension.number] = extension
    self._extensions_by_name[extension.containing_type][
        extension.full_name] = extension

    # Also register MessageSet extensions with the type name.
    if _IsMessageSetExtension(extension):
      self._extensions_by_name[extension.containing_type][
          extension.message_type.full_name] = extension 

def FindExtensionByName(self, full_name):
    """Loads the named extension descriptor from the pool.

    Args:
      full_name: The full name of the extension descriptor to load.

    Returns:
      A FieldDescriptor, describing the named extension.

    Raises:
      KeyError: if the extension cannot be found in the pool.
    """
    full_name = _NormalizeFullyQualifiedName(full_name)
    try:
      # The proto compiler does not give any link between the FileDescriptor
      # and top-level extensions unless the FileDescriptorProto is added to
      # the DescriptorDatabase, but this can impact memory usage.
      # So we registered these extensions by name explicitly.
      return self._toplevel_extensions[full_name]
    except KeyError:
      pass
    message_name, _, extension_name = full_name.rpartition('.')
    try:
      # Most extensions are nested inside a message.
      scope = self.FindMessageTypeByName(message_name)
    except KeyError:
      # Some extensions are defined at file scope.
      scope = self._FindFileContainingSymbolInDb(full_name)
    return scope.extensions_by_name[extension_name] 

def FindAllExtensions(self, message_descriptor):
    """Gets all the known extension of a given message.

    Extensions have to be registered to this pool by calling
    AddExtensionDescriptor.

    Args:
      message_descriptor: descriptor of the extended message.

    Returns:
      A list of FieldDescriptor describing the extensions.
    """
    return list(self._extensions_by_number[message_descriptor].values()) 

def _MakeFieldDescriptor(self, field_proto, message_name, index,
                           is_extension=False):
    """Creates a field descriptor from a FieldDescriptorProto.

    For message and enum type fields, this method will do a look up
    in the pool for the appropriate descriptor for that type. If it
    is unavailable, it will fall back to the _source function to
    create it. If this type is still unavailable, construction will
    fail.

    Args:
      field_proto: The proto describing the field.
      message_name: The name of the containing message.
      index: Index of the field
      is_extension: Indication that this field is for an extension.

    Returns:
      An initialized FieldDescriptor object
    """

    if message_name:
      full_name = '.'.join((message_name, field_proto.name))
    else:
      full_name = field_proto.name

    return descriptor.FieldDescriptor(
        name=field_proto.name,
        full_name=full_name,
        index=index,
        number=field_proto.number,
        type=field_proto.type,
        cpp_type=None,
        message_type=None,
        enum_type=None,
        containing_type=None,
        label=field_proto.label,
        has_default_value=False,
        default_value=None,
        is_extension=is_extension,
        extension_scope=None,
        options=_OptionsOrNone(field_proto)) 

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 GetTypeChecker(field):
  """Returns a type checker for a message field of the specified types.

  Args:
    field: FieldDescriptor object for this field.

  Returns:
    An instance of TypeChecker which can be used to verify the types
    of values assigned to a field of the specified type.
  """
  if (field.cpp_type == _FieldDescriptor.CPPTYPE_STRING and
      field.type == _FieldDescriptor.TYPE_STRING):
    return UnicodeValueChecker()
  if field.cpp_type == _FieldDescriptor.CPPTYPE_ENUM:
    if SupportsOpenEnums(field):
      # When open enums are supported, any int32 can be assigned.
      return _VALUE_CHECKERS[_FieldDescriptor.CPPTYPE_INT32]
    else:
      return EnumValueChecker(field.enum_type)
  return _VALUE_CHECKERS[field.cpp_type]


# None of the typecheckers below make any attempt to guard against people
# subclassing builtin types and doing weird things.  We're not trying to
# protect against malicious clients here, just people accidentally shooting
# themselves in the foot in obvious ways. 

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 == descriptor.FieldDescriptor.TYPE_MESSAGE and
          field.label == descriptor.FieldDescriptor.LABEL_OPTIONAL) 

def FindExtensionByName(self, full_name):
    """Loads the named extension descriptor from the pool.

    Args:
      full_name: The full name of the extension descriptor to load.

    Returns:
      A FieldDescriptor, describing the named extension.

    Raises:
      KeyError: if the extension cannot be found in the pool.
    """
    full_name = _NormalizeFullyQualifiedName(full_name)
    try:
      # The proto compiler does not give any link between the FileDescriptor
      # and top-level extensions unless the FileDescriptorProto is added to
      # the DescriptorDatabase, but this can impact memory usage.
      # So we registered these extensions by name explicitly.
      return self._toplevel_extensions[full_name]
    except KeyError:
      pass
    message_name, _, extension_name = full_name.rpartition('.')
    try:
      # Most extensions are nested inside a message.
      scope = self.FindMessageTypeByName(message_name)
    except KeyError:
      # Some extensions are defined at file scope.
      scope = self._FindFileContainingSymbolInDb(full_name)
    return scope.extensions_by_name[extension_name] 

def FindAllExtensions(self, message_descriptor):
    """Gets all the known extension of a given message.

    Extensions have to be registered to this pool by calling
    AddExtensionDescriptor.

    Args:
      message_descriptor: descriptor of the extended message.

    Returns:
      A list of FieldDescriptor describing the extensions.
    """
    return list(self._extensions_by_number[message_descriptor].values()) 

def testHandWrittenReflection(self):
    # 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',
        index=0, number=1, type=FieldDescriptor.TYPE_INT64,
        cpp_type=FieldDescriptor.CPPTYPE_INT64,
        label=FieldDescriptor.LABEL_OPTIONAL, default_value=0,
        containing_type=None, message_type=None, enum_type=None,
        is_extension=False, extension_scope=None,
        options=descriptor_pb2.FieldOptions())
    mydescriptor = descriptor.Descriptor(
        name='MyProto', full_name='MyProto', filename='ignored',
        containing_type=None, nested_types=[], enum_types=[],
        fields=[foo_field_descriptor], extensions=[],
        options=descriptor_pb2.MessageOptions())
    class MyProtoClass(six.with_metaclass(reflection.GeneratedProtocolMessageType, message.Message)):
      DESCRIPTOR = mydescriptor
    myproto_instance = MyProtoClass()
    self.assertEqual(0, myproto_instance.foo_field)
    self.assertTrue(not myproto_instance.HasField('foo_field'))
    myproto_instance.foo_field = 23
    self.assertEqual(23, myproto_instance.foo_field)
    self.assertTrue(myproto_instance.HasField('foo_field')) 

def testPackedOptions(self):
    proto = unittest_pb2.TestAllTypes()
    proto.optional_int32 = 1
    proto.optional_double = 3.0
    for field_descriptor, _ in proto.ListFields():
      self.assertEqual(False, field_descriptor.GetOptions().packed)

    proto = unittest_pb2.TestPackedTypes()
    proto.packed_int32.append(1)
    proto.packed_double.append(3.0)
    for field_descriptor, _ in proto.ListFields():
      self.assertEqual(True, field_descriptor.GetOptions().packed)
      self.assertEqual(descriptor.FieldDescriptor.LABEL_REPEATED,
                       field_descriptor.label) 

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 GetTypeChecker(field):
  """Returns a type checker for a message field of the specified types.

  Args:
    field: FieldDescriptor object for this field.

  Returns:
    An instance of TypeChecker which can be used to verify the types
    of values assigned to a field of the specified type.
  """
  if (field.cpp_type == _FieldDescriptor.CPPTYPE_STRING and
      field.type == _FieldDescriptor.TYPE_STRING):
    return UnicodeValueChecker()
  if field.cpp_type == _FieldDescriptor.CPPTYPE_ENUM:
    if SupportsOpenEnums(field):
      # When open enums are supported, any int32 can be assigned.
      return _VALUE_CHECKERS[_FieldDescriptor.CPPTYPE_INT32]
    else:
      return EnumValueChecker(field.enum_type)
  return _VALUE_CHECKERS[field.cpp_type]


# None of the typecheckers below make any attempt to guard against people
# subclassing builtin types and doing weird things.  We're not trying to
# protect against malicious clients here, just people accidentally shooting
# themselves in the foot in obvious ways. 

def _MakeFieldDescriptor(self, field_proto, message_name, index,
                           is_extension=False):
    """Creates a field descriptor from a FieldDescriptorProto.

    For message and enum type fields, this method will do a look up
    in the pool for the appropriate descriptor for that type. If it
    is unavailable, it will fall back to the _source function to
    create it. If this type is still unavailable, construction will
    fail.

    Args:
      field_proto: The proto describing the field.
      message_name: The name of the containing message.
      index: Index of the field
      is_extension: Indication that this field is for an extension.

    Returns:
      An initialized FieldDescriptor object
    """

    if message_name:
      full_name = '.'.join((message_name, field_proto.name))
    else:
      full_name = field_proto.name

    return descriptor.FieldDescriptor(
        name=field_proto.name,
        full_name=full_name,
        index=index,
        number=field_proto.number,
        type=field_proto.type,
        cpp_type=None,
        message_type=None,
        enum_type=None,
        containing_type=None,
        label=field_proto.label,
        has_default_value=False,
        default_value=None,
        is_extension=is_extension,
        extension_scope=None,
        options=_OptionsOrNone(field_proto)) 

def testHandWrittenReflection(self):
    # 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',
        index=0, number=1, type=FieldDescriptor.TYPE_INT64,
        cpp_type=FieldDescriptor.CPPTYPE_INT64,
        label=FieldDescriptor.LABEL_OPTIONAL, default_value=0,
        containing_type=None, message_type=None, enum_type=None,
        is_extension=False, extension_scope=None,
        options=descriptor_pb2.FieldOptions())
    mydescriptor = descriptor.Descriptor(
        name='MyProto', full_name='MyProto', filename='ignored',
        containing_type=None, nested_types=[], enum_types=[],
        fields=[foo_field_descriptor], extensions=[],
        options=descriptor_pb2.MessageOptions())
    class MyProtoClass(six.with_metaclass(reflection.GeneratedProtocolMessageType, message.Message)):
      DESCRIPTOR = mydescriptor
    myproto_instance = MyProtoClass()
    self.assertEqual(0, myproto_instance.foo_field)
    self.assertTrue(not myproto_instance.HasField('foo_field'))
    myproto_instance.foo_field = 23
    self.assertEqual(23, myproto_instance.foo_field)
    self.assertTrue(myproto_instance.HasField('foo_field')) 

def testPackedOptions(self):
    proto = unittest_pb2.TestAllTypes()
    proto.optional_int32 = 1
    proto.optional_double = 3.0
    for field_descriptor, _ in proto.ListFields():
      self.assertEqual(False, field_descriptor.GetOptions().packed)

    proto = unittest_pb2.TestPackedTypes()
    proto.packed_int32.append(1)
    proto.packed_double.append(3.0)
    for field_descriptor, _ in proto.ListFields():
      self.assertEqual(True, field_descriptor.GetOptions().packed)
      self.assertEqual(descriptor.FieldDescriptor.LABEL_REPEATED,
                       field_descriptor.label) 

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 GetTypeChecker(field):
  """Returns a type checker for a message field of the specified types.

  Args:
    field: FieldDescriptor object for this field.

  Returns:
    An instance of TypeChecker which can be used to verify the types
    of values assigned to a field of the specified type.
  """
  if (field.cpp_type == _FieldDescriptor.CPPTYPE_STRING and
      field.type == _FieldDescriptor.TYPE_STRING):
    return UnicodeValueChecker()
  if field.cpp_type == _FieldDescriptor.CPPTYPE_ENUM:
    if SupportsOpenEnums(field):
      # When open enums are supported, any int32 can be assigned.
      return _VALUE_CHECKERS[_FieldDescriptor.CPPTYPE_INT32]
    else:
      return EnumValueChecker(field.enum_type)
  return _VALUE_CHECKERS[field.cpp_type]


# None of the typecheckers below make any attempt to guard against people
# subclassing builtin types and doing weird things.  We're not trying to
# protect against malicious clients here, just people accidentally shooting
# themselves in the foot in obvious ways. 

def generate_type_enum():
    TYPE_ = 'TYPE_'
    a = [(x[len(TYPE_):], getattr(FieldDescriptor, x)) for x in dir(FieldDescriptor) if x.startswith(TYPE_)]

    r = '''
class PBType(Enum):
'''
    for k, v in a:
        r += f'    {k} = {v}\n'
    return r 

def generate_label_enum():
    TYPE_ = 'LABEL_'
    a = [(x[len(TYPE_):], getattr(FieldDescriptor, x)) for x in dir(FieldDescriptor) if x.startswith(TYPE_)]

    r = '''
class PBLabel(Enum):
'''
    for k, v in a:
        r += f'    {k} = {v}\n'
    return r 

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 == descriptor.FieldDescriptor.TYPE_MESSAGE and
          field.label == descriptor.FieldDescriptor.LABEL_OPTIONAL)