python/google/protobuf/internal/type_checkers.py - third_party/github/protocolbuffers/protobuf - Git at Google

 # Protocol Buffers - Google's data interchange format
 # Copyright 2008 Google Inc.  All rights reserved.
 #
 # Use of this source code is governed by a BSD-style
 # license that can be found in the LICENSE file or at
 # https://developers.google.com/open-source/licenses/bsd

 """Provides type checking routines.

 This module defines type checking utilities in the forms of dictionaries:

 VALUE_CHECKERS: A dictionary of field types and a value validation object.
 TYPE_TO_BYTE_SIZE_FN: A dictionary with field types and a size computing
   function.
 TYPE_TO_SERIALIZE_METHOD: A dictionary with field types and serialization
   function.
 FIELD_TYPE_TO_WIRE_TYPE: A dictionary with field typed and their
   corresponding wire types.
 TYPE_TO_DESERIALIZE_METHOD: A dictionary with field types and deserialization
   function.
 """

 __author__ = 'robinson@google.com (Will Robinson)'

 import struct
 import numbers

 from google.protobuf.internal import decoder
 from google.protobuf.internal import encoder
 from google.protobuf.internal import wire_format
 from google.protobuf import descriptor

 _FieldDescriptor = descriptor.FieldDescriptor


 def TruncateToFourByteFloat(original):
   return struct.unpack('<f', struct.pack('<f', original))[0]


 def ToShortestFloat(original):
   """Returns the shortest float that has same value in wire."""
   # All 4 byte floats have between 6 and 9 significant digits, so we
   # start with 6 as the lower bound.
   # It has to be iterative because use '.9g' directly can not get rid
   # of the noises for most values. For example if set a float_field=0.9
   # use '.9g' will print 0.899999976.
   precision = 6
   rounded = float('{0:.{1}g}'.format(original, precision))
   while TruncateToFourByteFloat(rounded) != original:
     precision += 1
     rounded = float('{0:.{1}g}'.format(original, precision))
   return rounded


 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 field.enum_type.is_closed:
       return EnumValueChecker(field.enum_type)
     else:
       # When open enums are supported, any int32 can be assigned.
       return _VALUE_CHECKERS[_FieldDescriptor.CPPTYPE_INT32]
   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.
 class TypeChecker(object):

   """Type checker used to catch type errors as early as possible
   when the client is setting scalar fields in protocol messages.
   """

   def __init__(self, *acceptable_types):
     self._acceptable_types = acceptable_types

   def CheckValue(self, proposed_value):
     """Type check the provided value and return it.

     The returned value might have been normalized to another type.
     """
     if not isinstance(proposed_value, self._acceptable_types):
       message = ('%.1024r has type %s, but expected one of: %s' %
                  (proposed_value, type(proposed_value), self._acceptable_types))
       raise TypeError(message)
     return proposed_value


 class TypeCheckerWithDefault(TypeChecker):

   def __init__(self, default_value, *acceptable_types):
     TypeChecker.__init__(self, *acceptable_types)
     self._default_value = default_value

   def DefaultValue(self):
     return self._default_value


 class BoolValueChecker(object):
   """Type checker used for bool fields."""

   def CheckValue(self, proposed_value):
     if not hasattr(proposed_value, '__index__') or (
         type(proposed_value).__module__ == 'numpy' and
         type(proposed_value).__name__ == 'ndarray'):
       message = ('%.1024r has type %s, but expected one of: %s' %
                  (proposed_value, type(proposed_value), (bool, int)))
       raise TypeError(message)
     return bool(proposed_value)

   def DefaultValue(self):
     return False


 # IntValueChecker and its subclasses perform integer type-checks
 # and bounds-checks.
 class IntValueChecker(object):

   """Checker used for integer fields.  Performs type-check and range check."""

   def CheckValue(self, proposed_value):
     if not hasattr(proposed_value, '__index__') or (
         type(proposed_value).__module__ == 'numpy' and
         type(proposed_value).__name__ == 'ndarray'):
       message = ('%.1024r has type %s, but expected one of: %s' %
                  (proposed_value, type(proposed_value), (int,)))
       raise TypeError(message)

     if not self._MIN <= int(proposed_value) <= self._MAX:
       raise ValueError('Value out of range: %d' % proposed_value)
     # We force all values to int to make alternate implementations where the
     # distinction is more significant (e.g. the C++ implementation) simpler.
     proposed_value = int(proposed_value)
     return proposed_value

   def DefaultValue(self):
     return 0


 class EnumValueChecker(object):

   """Checker used for enum fields.  Performs type-check and range check."""

   def __init__(self, enum_type):
     self._enum_type = enum_type

   def CheckValue(self, proposed_value):
     if not isinstance(proposed_value, numbers.Integral):
       message = ('%.1024r has type %s, but expected one of: %s' %
                  (proposed_value, type(proposed_value), (int,)))
       raise TypeError(message)
     if int(proposed_value) not in self._enum_type.values_by_number:
       raise ValueError('Unknown enum value: %d' % proposed_value)
     return proposed_value

   def DefaultValue(self):
     return self._enum_type.values[0].number


 class UnicodeValueChecker(object):

   """Checker used for string fields.

   Always returns a unicode value, even if the input is of type str.
   """

   def CheckValue(self, proposed_value):
     if not isinstance(proposed_value, (bytes, str)):
       message = ('%.1024r has type %s, but expected one of: %s' %
                  (proposed_value, type(proposed_value), (bytes, str)))
       raise TypeError(message)

     # If the value is of type 'bytes' make sure that it is valid UTF-8 data.
     if isinstance(proposed_value, bytes):
       try:
         proposed_value = proposed_value.decode('utf-8')
       except UnicodeDecodeError:
         raise ValueError('%.1024r has type bytes, but isn\'t valid UTF-8 '
                          'encoding. Non-UTF-8 strings must be converted to '
                          'unicode objects before being added.' %
                          (proposed_value))
     else:
       try:
         proposed_value.encode('utf8')
       except UnicodeEncodeError:
         raise ValueError('%.1024r isn\'t a valid unicode string and '
                          'can\'t be encoded in UTF-8.'%
                          (proposed_value))

     return proposed_value

   def DefaultValue(self):
     return u""


 class Int32ValueChecker(IntValueChecker):
   # We're sure to use ints instead of longs here since comparison may be more
   # efficient.
   _MIN = -2147483648
   _MAX = 2147483647


 class Uint32ValueChecker(IntValueChecker):
   _MIN = 0
   _MAX = (1 << 32) - 1


 class Int64ValueChecker(IntValueChecker):
   _MIN = -(1 << 63)
   _MAX = (1 << 63) - 1


 class Uint64ValueChecker(IntValueChecker):
   _MIN = 0
   _MAX = (1 << 64) - 1


 # The max 4 bytes float is about 3.4028234663852886e+38
 _FLOAT_MAX = float.fromhex('0x1.fffffep+127')
 _FLOAT_MIN = -_FLOAT_MAX
 _INF = float('inf')
 _NEG_INF = float('-inf')


 class DoubleValueChecker(object):
   """Checker used for double fields.

   Performs type-check and range check.
   """

   def CheckValue(self, proposed_value):
     """Check and convert proposed_value to float."""
     if (not hasattr(proposed_value, '__float__') and
         not hasattr(proposed_value, '__index__')) or (
             type(proposed_value).__module__ == 'numpy' and
             type(proposed_value).__name__ == 'ndarray'):
       message = ('%.1024r has type %s, but expected one of: int, float' %
                  (proposed_value, type(proposed_value)))
       raise TypeError(message)
     return float(proposed_value)

   def DefaultValue(self):
     return 0.0


 class FloatValueChecker(DoubleValueChecker):
   """Checker used for float fields.

   Performs type-check and range check.

   Values exceeding a 32-bit float will be converted to inf/-inf.
   """

   def CheckValue(self, proposed_value):
     """Check and convert proposed_value to float."""
     converted_value = super().CheckValue(proposed_value)
     # This inf rounding matches the C++ proto SafeDoubleToFloat logic.
     if converted_value > _FLOAT_MAX:
       return _INF
     if converted_value < _FLOAT_MIN:
       return _NEG_INF

     return TruncateToFourByteFloat(converted_value)

 # Type-checkers for all scalar CPPTYPEs.
 _VALUE_CHECKERS = {
     _FieldDescriptor.CPPTYPE_INT32: Int32ValueChecker(),
     _FieldDescriptor.CPPTYPE_INT64: Int64ValueChecker(),
     _FieldDescriptor.CPPTYPE_UINT32: Uint32ValueChecker(),
     _FieldDescriptor.CPPTYPE_UINT64: Uint64ValueChecker(),
     _FieldDescriptor.CPPTYPE_DOUBLE: DoubleValueChecker(),
     _FieldDescriptor.CPPTYPE_FLOAT: FloatValueChecker(),
     _FieldDescriptor.CPPTYPE_BOOL: BoolValueChecker(),
     _FieldDescriptor.CPPTYPE_STRING: TypeCheckerWithDefault(b'', bytes),
 }


 # Map from field type to a function F, such that F(field_num, value)
 # gives the total byte size for a value of the given type.  This
 # byte size includes tag information and any other additional space
 # associated with serializing "value".
 TYPE_TO_BYTE_SIZE_FN = {
     _FieldDescriptor.TYPE_DOUBLE: wire_format.DoubleByteSize,
     _FieldDescriptor.TYPE_FLOAT: wire_format.FloatByteSize,
     _FieldDescriptor.TYPE_INT64: wire_format.Int64ByteSize,
     _FieldDescriptor.TYPE_UINT64: wire_format.UInt64ByteSize,
     _FieldDescriptor.TYPE_INT32: wire_format.Int32ByteSize,
     _FieldDescriptor.TYPE_FIXED64: wire_format.Fixed64ByteSize,
     _FieldDescriptor.TYPE_FIXED32: wire_format.Fixed32ByteSize,
     _FieldDescriptor.TYPE_BOOL: wire_format.BoolByteSize,
     _FieldDescriptor.TYPE_STRING: wire_format.StringByteSize,
     _FieldDescriptor.TYPE_GROUP: wire_format.GroupByteSize,
     _FieldDescriptor.TYPE_MESSAGE: wire_format.MessageByteSize,
     _FieldDescriptor.TYPE_BYTES: wire_format.BytesByteSize,
     _FieldDescriptor.TYPE_UINT32: wire_format.UInt32ByteSize,
     _FieldDescriptor.TYPE_ENUM: wire_format.EnumByteSize,
     _FieldDescriptor.TYPE_SFIXED32: wire_format.SFixed32ByteSize,
     _FieldDescriptor.TYPE_SFIXED64: wire_format.SFixed64ByteSize,
     _FieldDescriptor.TYPE_SINT32: wire_format.SInt32ByteSize,
     _FieldDescriptor.TYPE_SINT64: wire_format.SInt64ByteSize
     }


 # Maps from field types to encoder constructors.
 TYPE_TO_ENCODER = {
     _FieldDescriptor.TYPE_DOUBLE: encoder.DoubleEncoder,
     _FieldDescriptor.TYPE_FLOAT: encoder.FloatEncoder,
     _FieldDescriptor.TYPE_INT64: encoder.Int64Encoder,
     _FieldDescriptor.TYPE_UINT64: encoder.UInt64Encoder,
     _FieldDescriptor.TYPE_INT32: encoder.Int32Encoder,
     _FieldDescriptor.TYPE_FIXED64: encoder.Fixed64Encoder,
     _FieldDescriptor.TYPE_FIXED32: encoder.Fixed32Encoder,
     _FieldDescriptor.TYPE_BOOL: encoder.BoolEncoder,
     _FieldDescriptor.TYPE_STRING: encoder.StringEncoder,
     _FieldDescriptor.TYPE_GROUP: encoder.GroupEncoder,
     _FieldDescriptor.TYPE_MESSAGE: encoder.MessageEncoder,
     _FieldDescriptor.TYPE_BYTES: encoder.BytesEncoder,
     _FieldDescriptor.TYPE_UINT32: encoder.UInt32Encoder,
     _FieldDescriptor.TYPE_ENUM: encoder.EnumEncoder,
     _FieldDescriptor.TYPE_SFIXED32: encoder.SFixed32Encoder,
     _FieldDescriptor.TYPE_SFIXED64: encoder.SFixed64Encoder,
     _FieldDescriptor.TYPE_SINT32: encoder.SInt32Encoder,
     _FieldDescriptor.TYPE_SINT64: encoder.SInt64Encoder,
     }


 # Maps from field types to sizer constructors.
 TYPE_TO_SIZER = {
     _FieldDescriptor.TYPE_DOUBLE: encoder.DoubleSizer,
     _FieldDescriptor.TYPE_FLOAT: encoder.FloatSizer,
     _FieldDescriptor.TYPE_INT64: encoder.Int64Sizer,
     _FieldDescriptor.TYPE_UINT64: encoder.UInt64Sizer,
     _FieldDescriptor.TYPE_INT32: encoder.Int32Sizer,
     _FieldDescriptor.TYPE_FIXED64: encoder.Fixed64Sizer,
     _FieldDescriptor.TYPE_FIXED32: encoder.Fixed32Sizer,
     _FieldDescriptor.TYPE_BOOL: encoder.BoolSizer,
     _FieldDescriptor.TYPE_STRING: encoder.StringSizer,
     _FieldDescriptor.TYPE_GROUP: encoder.GroupSizer,
     _FieldDescriptor.TYPE_MESSAGE: encoder.MessageSizer,
     _FieldDescriptor.TYPE_BYTES: encoder.BytesSizer,
     _FieldDescriptor.TYPE_UINT32: encoder.UInt32Sizer,
     _FieldDescriptor.TYPE_ENUM: encoder.EnumSizer,
     _FieldDescriptor.TYPE_SFIXED32: encoder.SFixed32Sizer,
     _FieldDescriptor.TYPE_SFIXED64: encoder.SFixed64Sizer,
     _FieldDescriptor.TYPE_SINT32: encoder.SInt32Sizer,
     _FieldDescriptor.TYPE_SINT64: encoder.SInt64Sizer,
     }


 # Maps from field type to a decoder constructor.
 TYPE_TO_DECODER = {
     _FieldDescriptor.TYPE_DOUBLE: decoder.DoubleDecoder,
     _FieldDescriptor.TYPE_FLOAT: decoder.FloatDecoder,
     _FieldDescriptor.TYPE_INT64: decoder.Int64Decoder,
     _FieldDescriptor.TYPE_UINT64: decoder.UInt64Decoder,
     _FieldDescriptor.TYPE_INT32: decoder.Int32Decoder,
     _FieldDescriptor.TYPE_FIXED64: decoder.Fixed64Decoder,
     _FieldDescriptor.TYPE_FIXED32: decoder.Fixed32Decoder,
     _FieldDescriptor.TYPE_BOOL: decoder.BoolDecoder,
     _FieldDescriptor.TYPE_STRING: decoder.StringDecoder,
     _FieldDescriptor.TYPE_GROUP: decoder.GroupDecoder,
     _FieldDescriptor.TYPE_MESSAGE: decoder.MessageDecoder,
     _FieldDescriptor.TYPE_BYTES: decoder.BytesDecoder,
     _FieldDescriptor.TYPE_UINT32: decoder.UInt32Decoder,
     _FieldDescriptor.TYPE_ENUM: decoder.EnumDecoder,
     _FieldDescriptor.TYPE_SFIXED32: decoder.SFixed32Decoder,
     _FieldDescriptor.TYPE_SFIXED64: decoder.SFixed64Decoder,
     _FieldDescriptor.TYPE_SINT32: decoder.SInt32Decoder,
     _FieldDescriptor.TYPE_SINT64: decoder.SInt64Decoder,
     }

 # Maps from field type to expected wiretype.
 FIELD_TYPE_TO_WIRE_TYPE = {
     _FieldDescriptor.TYPE_DOUBLE: wire_format.WIRETYPE_FIXED64,
     _FieldDescriptor.TYPE_FLOAT: wire_format.WIRETYPE_FIXED32,
     _FieldDescriptor.TYPE_INT64: wire_format.WIRETYPE_VARINT,
     _FieldDescriptor.TYPE_UINT64: wire_format.WIRETYPE_VARINT,
     _FieldDescriptor.TYPE_INT32: wire_format.WIRETYPE_VARINT,
     _FieldDescriptor.TYPE_FIXED64: wire_format.WIRETYPE_FIXED64,
     _FieldDescriptor.TYPE_FIXED32: wire_format.WIRETYPE_FIXED32,
     _FieldDescriptor.TYPE_BOOL: wire_format.WIRETYPE_VARINT,
     _FieldDescriptor.TYPE_STRING:
       wire_format.WIRETYPE_LENGTH_DELIMITED,
     _FieldDescriptor.TYPE_GROUP: wire_format.WIRETYPE_START_GROUP,
     _FieldDescriptor.TYPE_MESSAGE:
       wire_format.WIRETYPE_LENGTH_DELIMITED,
     _FieldDescriptor.TYPE_BYTES:
       wire_format.WIRETYPE_LENGTH_DELIMITED,
     _FieldDescriptor.TYPE_UINT32: wire_format.WIRETYPE_VARINT,
     _FieldDescriptor.TYPE_ENUM: wire_format.WIRETYPE_VARINT,
     _FieldDescriptor.TYPE_SFIXED32: wire_format.WIRETYPE_FIXED32,
     _FieldDescriptor.TYPE_SFIXED64: wire_format.WIRETYPE_FIXED64,
     _FieldDescriptor.TYPE_SINT32: wire_format.WIRETYPE_VARINT,
     _FieldDescriptor.TYPE_SINT64: wire_format.WIRETYPE_VARINT,
     }
	# Protocol Buffers - Google's data interchange format
	# Copyright 2008 Google Inc. All rights reserved.
	#
	# Use of this source code is governed by a BSD-style
	# license that can be found in the LICENSE file or at
	# https://developers.google.com/open-source/licenses/bsd

	"""Provides type checking routines.

	This module defines type checking utilities in the forms of dictionaries:

	VALUE_CHECKERS: A dictionary of field types and a value validation object.
	TYPE_TO_BYTE_SIZE_FN: A dictionary with field types and a size computing
	function.
	TYPE_TO_SERIALIZE_METHOD: A dictionary with field types and serialization
	function.
	FIELD_TYPE_TO_WIRE_TYPE: A dictionary with field typed and their
	corresponding wire types.
	TYPE_TO_DESERIALIZE_METHOD: A dictionary with field types and deserialization
	function.
	"""

	__author__ = 'robinson@google.com (Will Robinson)'

	import struct
	import numbers

	from google.protobuf.internal import decoder
	from google.protobuf.internal import encoder
	from google.protobuf.internal import wire_format
	from google.protobuf import descriptor

	_FieldDescriptor = descriptor.FieldDescriptor


	def TruncateToFourByteFloat(original):
	return struct.unpack('<f', struct.pack('<f', original))[0]


	def ToShortestFloat(original):
	"""Returns the shortest float that has same value in wire."""
	# All 4 byte floats have between 6 and 9 significant digits, so we
	# start with 6 as the lower bound.
	# It has to be iterative because use '.9g' directly can not get rid
	# of the noises for most values. For example if set a float_field=0.9
	# use '.9g' will print 0.899999976.
	precision = 6
	rounded = float('{0:.{1}g}'.format(original, precision))
	while TruncateToFourByteFloat(rounded) != original:
	precision += 1
	rounded = float('{0:.{1}g}'.format(original, precision))
	return rounded


	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 field.enum_type.is_closed:
	return EnumValueChecker(field.enum_type)
	else:
	# When open enums are supported, any int32 can be assigned.
	return _VALUE_CHECKERS[_FieldDescriptor.CPPTYPE_INT32]
	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.
	class TypeChecker(object):

	"""Type checker used to catch type errors as early as possible
	when the client is setting scalar fields in protocol messages.
	"""

	def __init__(self, *acceptable_types):
	self._acceptable_types = acceptable_types

	def CheckValue(self, proposed_value):
	"""Type check the provided value and return it.

	The returned value might have been normalized to another type.
	"""
	if not isinstance(proposed_value, self._acceptable_types):
	message = ('%.1024r has type %s, but expected one of: %s' %
	(proposed_value, type(proposed_value), self._acceptable_types))
	raise TypeError(message)
	return proposed_value


	class TypeCheckerWithDefault(TypeChecker):

	def __init__(self, default_value, *acceptable_types):
	TypeChecker.__init__(self, *acceptable_types)
	self._default_value = default_value

	def DefaultValue(self):
	return self._default_value


	class BoolValueChecker(object):
	"""Type checker used for bool fields."""

	def CheckValue(self, proposed_value):
	if not hasattr(proposed_value, '__index__') or (
	type(proposed_value).__module__ == 'numpy' and
	type(proposed_value).__name__ == 'ndarray'):
	message = ('%.1024r has type %s, but expected one of: %s' %
	(proposed_value, type(proposed_value), (bool, int)))
	raise TypeError(message)
	return bool(proposed_value)

	def DefaultValue(self):
	return False


	# IntValueChecker and its subclasses perform integer type-checks
	# and bounds-checks.
	class IntValueChecker(object):

	"""Checker used for integer fields. Performs type-check and range check."""

	def CheckValue(self, proposed_value):
	if not hasattr(proposed_value, '__index__') or (
	type(proposed_value).__module__ == 'numpy' and
	type(proposed_value).__name__ == 'ndarray'):
	message = ('%.1024r has type %s, but expected one of: %s' %
	(proposed_value, type(proposed_value), (int,)))
	raise TypeError(message)

	if not self._MIN <= int(proposed_value) <= self._MAX:
	raise ValueError('Value out of range: %d' % proposed_value)
	# We force all values to int to make alternate implementations where the
	# distinction is more significant (e.g. the C++ implementation) simpler.
	proposed_value = int(proposed_value)
	return proposed_value

	def DefaultValue(self):
	return 0


	class EnumValueChecker(object):

	"""Checker used for enum fields. Performs type-check and range check."""

	def __init__(self, enum_type):
	self._enum_type = enum_type

	def CheckValue(self, proposed_value):
	if not isinstance(proposed_value, numbers.Integral):
	message = ('%.1024r has type %s, but expected one of: %s' %
	(proposed_value, type(proposed_value), (int,)))
	raise TypeError(message)
	if int(proposed_value) not in self._enum_type.values_by_number:
	raise ValueError('Unknown enum value: %d' % proposed_value)
	return proposed_value

	def DefaultValue(self):
	return self._enum_type.values[0].number


	class UnicodeValueChecker(object):

	"""Checker used for string fields.

	Always returns a unicode value, even if the input is of type str.
	"""

	def CheckValue(self, proposed_value):
	if not isinstance(proposed_value, (bytes, str)):
	message = ('%.1024r has type %s, but expected one of: %s' %
	(proposed_value, type(proposed_value), (bytes, str)))
	raise TypeError(message)

	# If the value is of type 'bytes' make sure that it is valid UTF-8 data.
	if isinstance(proposed_value, bytes):
	try:
	proposed_value = proposed_value.decode('utf-8')
	except UnicodeDecodeError:
	raise ValueError('%.1024r has type bytes, but isn\'t valid UTF-8 '
	'encoding. Non-UTF-8 strings must be converted to '
	'unicode objects before being added.' %
	(proposed_value))
	else:
	try:
	proposed_value.encode('utf8')
	except UnicodeEncodeError:
	raise ValueError('%.1024r isn\'t a valid unicode string and '
	'can\'t be encoded in UTF-8.'%
	(proposed_value))

	return proposed_value

	def DefaultValue(self):
	return u""


	class Int32ValueChecker(IntValueChecker):
	# We're sure to use ints instead of longs here since comparison may be more
	# efficient.
	_MIN = -2147483648
	_MAX = 2147483647


	class Uint32ValueChecker(IntValueChecker):
	_MIN = 0
	_MAX = (1 << 32) - 1


	class Int64ValueChecker(IntValueChecker):
	_MIN = -(1 << 63)
	_MAX = (1 << 63) - 1


	class Uint64ValueChecker(IntValueChecker):
	_MIN = 0
	_MAX = (1 << 64) - 1


	# The max 4 bytes float is about 3.4028234663852886e+38
	_FLOAT_MAX = float.fromhex('0x1.fffffep+127')
	_FLOAT_MIN = -_FLOAT_MAX
	_INF = float('inf')
	_NEG_INF = float('-inf')


	class DoubleValueChecker(object):
	"""Checker used for double fields.

	Performs type-check and range check.
	"""

	def CheckValue(self, proposed_value):
	"""Check and convert proposed_value to float."""
	if (not hasattr(proposed_value, '__float__') and
	not hasattr(proposed_value, '__index__')) or (
	type(proposed_value).__module__ == 'numpy' and
	type(proposed_value).__name__ == 'ndarray'):
	message = ('%.1024r has type %s, but expected one of: int, float' %
	(proposed_value, type(proposed_value)))
	raise TypeError(message)
	return float(proposed_value)

	def DefaultValue(self):
	return 0.0


	class FloatValueChecker(DoubleValueChecker):
	"""Checker used for float fields.

	Performs type-check and range check.

	Values exceeding a 32-bit float will be converted to inf/-inf.
	"""

	def CheckValue(self, proposed_value):
	"""Check and convert proposed_value to float."""
	converted_value = super().CheckValue(proposed_value)
	# This inf rounding matches the C++ proto SafeDoubleToFloat logic.
	if converted_value > _FLOAT_MAX:
	return _INF
	if converted_value < _FLOAT_MIN:
	return _NEG_INF

	return TruncateToFourByteFloat(converted_value)

	# Type-checkers for all scalar CPPTYPEs.
	_VALUE_CHECKERS = {
	_FieldDescriptor.CPPTYPE_INT32: Int32ValueChecker(),
	_FieldDescriptor.CPPTYPE_INT64: Int64ValueChecker(),
	_FieldDescriptor.CPPTYPE_UINT32: Uint32ValueChecker(),
	_FieldDescriptor.CPPTYPE_UINT64: Uint64ValueChecker(),
	_FieldDescriptor.CPPTYPE_DOUBLE: DoubleValueChecker(),
	_FieldDescriptor.CPPTYPE_FLOAT: FloatValueChecker(),
	_FieldDescriptor.CPPTYPE_BOOL: BoolValueChecker(),
	_FieldDescriptor.CPPTYPE_STRING: TypeCheckerWithDefault(b'', bytes),
	}


	# Map from field type to a function F, such that F(field_num, value)
	# gives the total byte size for a value of the given type. This
	# byte size includes tag information and any other additional space
	# associated with serializing "value".
	TYPE_TO_BYTE_SIZE_FN = {
	_FieldDescriptor.TYPE_DOUBLE: wire_format.DoubleByteSize,
	_FieldDescriptor.TYPE_FLOAT: wire_format.FloatByteSize,
	_FieldDescriptor.TYPE_INT64: wire_format.Int64ByteSize,
	_FieldDescriptor.TYPE_UINT64: wire_format.UInt64ByteSize,
	_FieldDescriptor.TYPE_INT32: wire_format.Int32ByteSize,
	_FieldDescriptor.TYPE_FIXED64: wire_format.Fixed64ByteSize,
	_FieldDescriptor.TYPE_FIXED32: wire_format.Fixed32ByteSize,
	_FieldDescriptor.TYPE_BOOL: wire_format.BoolByteSize,
	_FieldDescriptor.TYPE_STRING: wire_format.StringByteSize,
	_FieldDescriptor.TYPE_GROUP: wire_format.GroupByteSize,
	_FieldDescriptor.TYPE_MESSAGE: wire_format.MessageByteSize,
	_FieldDescriptor.TYPE_BYTES: wire_format.BytesByteSize,
	_FieldDescriptor.TYPE_UINT32: wire_format.UInt32ByteSize,
	_FieldDescriptor.TYPE_ENUM: wire_format.EnumByteSize,
	_FieldDescriptor.TYPE_SFIXED32: wire_format.SFixed32ByteSize,
	_FieldDescriptor.TYPE_SFIXED64: wire_format.SFixed64ByteSize,
	_FieldDescriptor.TYPE_SINT32: wire_format.SInt32ByteSize,
	_FieldDescriptor.TYPE_SINT64: wire_format.SInt64ByteSize
	}


	# Maps from field types to encoder constructors.
	TYPE_TO_ENCODER = {
	_FieldDescriptor.TYPE_DOUBLE: encoder.DoubleEncoder,
	_FieldDescriptor.TYPE_FLOAT: encoder.FloatEncoder,
	_FieldDescriptor.TYPE_INT64: encoder.Int64Encoder,
	_FieldDescriptor.TYPE_UINT64: encoder.UInt64Encoder,
	_FieldDescriptor.TYPE_INT32: encoder.Int32Encoder,
	_FieldDescriptor.TYPE_FIXED64: encoder.Fixed64Encoder,
	_FieldDescriptor.TYPE_FIXED32: encoder.Fixed32Encoder,
	_FieldDescriptor.TYPE_BOOL: encoder.BoolEncoder,
	_FieldDescriptor.TYPE_STRING: encoder.StringEncoder,
	_FieldDescriptor.TYPE_GROUP: encoder.GroupEncoder,
	_FieldDescriptor.TYPE_MESSAGE: encoder.MessageEncoder,
	_FieldDescriptor.TYPE_BYTES: encoder.BytesEncoder,
	_FieldDescriptor.TYPE_UINT32: encoder.UInt32Encoder,
	_FieldDescriptor.TYPE_ENUM: encoder.EnumEncoder,
	_FieldDescriptor.TYPE_SFIXED32: encoder.SFixed32Encoder,
	_FieldDescriptor.TYPE_SFIXED64: encoder.SFixed64Encoder,
	_FieldDescriptor.TYPE_SINT32: encoder.SInt32Encoder,
	_FieldDescriptor.TYPE_SINT64: encoder.SInt64Encoder,
	}


	# Maps from field types to sizer constructors.
	TYPE_TO_SIZER = {
	_FieldDescriptor.TYPE_DOUBLE: encoder.DoubleSizer,
	_FieldDescriptor.TYPE_FLOAT: encoder.FloatSizer,
	_FieldDescriptor.TYPE_INT64: encoder.Int64Sizer,
	_FieldDescriptor.TYPE_UINT64: encoder.UInt64Sizer,
	_FieldDescriptor.TYPE_INT32: encoder.Int32Sizer,
	_FieldDescriptor.TYPE_FIXED64: encoder.Fixed64Sizer,
	_FieldDescriptor.TYPE_FIXED32: encoder.Fixed32Sizer,
	_FieldDescriptor.TYPE_BOOL: encoder.BoolSizer,
	_FieldDescriptor.TYPE_STRING: encoder.StringSizer,
	_FieldDescriptor.TYPE_GROUP: encoder.GroupSizer,
	_FieldDescriptor.TYPE_MESSAGE: encoder.MessageSizer,
	_FieldDescriptor.TYPE_BYTES: encoder.BytesSizer,
	_FieldDescriptor.TYPE_UINT32: encoder.UInt32Sizer,
	_FieldDescriptor.TYPE_ENUM: encoder.EnumSizer,
	_FieldDescriptor.TYPE_SFIXED32: encoder.SFixed32Sizer,
	_FieldDescriptor.TYPE_SFIXED64: encoder.SFixed64Sizer,
	_FieldDescriptor.TYPE_SINT32: encoder.SInt32Sizer,
	_FieldDescriptor.TYPE_SINT64: encoder.SInt64Sizer,
	}


	# Maps from field type to a decoder constructor.
	TYPE_TO_DECODER = {
	_FieldDescriptor.TYPE_DOUBLE: decoder.DoubleDecoder,
	_FieldDescriptor.TYPE_FLOAT: decoder.FloatDecoder,
	_FieldDescriptor.TYPE_INT64: decoder.Int64Decoder,
	_FieldDescriptor.TYPE_UINT64: decoder.UInt64Decoder,
	_FieldDescriptor.TYPE_INT32: decoder.Int32Decoder,
	_FieldDescriptor.TYPE_FIXED64: decoder.Fixed64Decoder,
	_FieldDescriptor.TYPE_FIXED32: decoder.Fixed32Decoder,
	_FieldDescriptor.TYPE_BOOL: decoder.BoolDecoder,
	_FieldDescriptor.TYPE_STRING: decoder.StringDecoder,
	_FieldDescriptor.TYPE_GROUP: decoder.GroupDecoder,
	_FieldDescriptor.TYPE_MESSAGE: decoder.MessageDecoder,
	_FieldDescriptor.TYPE_BYTES: decoder.BytesDecoder,
	_FieldDescriptor.TYPE_UINT32: decoder.UInt32Decoder,
	_FieldDescriptor.TYPE_ENUM: decoder.EnumDecoder,
	_FieldDescriptor.TYPE_SFIXED32: decoder.SFixed32Decoder,
	_FieldDescriptor.TYPE_SFIXED64: decoder.SFixed64Decoder,
	_FieldDescriptor.TYPE_SINT32: decoder.SInt32Decoder,
	_FieldDescriptor.TYPE_SINT64: decoder.SInt64Decoder,
	}

	# Maps from field type to expected wiretype.
	FIELD_TYPE_TO_WIRE_TYPE = {
	_FieldDescriptor.TYPE_DOUBLE: wire_format.WIRETYPE_FIXED64,
	_FieldDescriptor.TYPE_FLOAT: wire_format.WIRETYPE_FIXED32,
	_FieldDescriptor.TYPE_INT64: wire_format.WIRETYPE_VARINT,
	_FieldDescriptor.TYPE_UINT64: wire_format.WIRETYPE_VARINT,
	_FieldDescriptor.TYPE_INT32: wire_format.WIRETYPE_VARINT,
	_FieldDescriptor.TYPE_FIXED64: wire_format.WIRETYPE_FIXED64,
	_FieldDescriptor.TYPE_FIXED32: wire_format.WIRETYPE_FIXED32,
	_FieldDescriptor.TYPE_BOOL: wire_format.WIRETYPE_VARINT,
	_FieldDescriptor.TYPE_STRING:
	wire_format.WIRETYPE_LENGTH_DELIMITED,
	_FieldDescriptor.TYPE_GROUP: wire_format.WIRETYPE_START_GROUP,
	_FieldDescriptor.TYPE_MESSAGE:
	wire_format.WIRETYPE_LENGTH_DELIMITED,
	_FieldDescriptor.TYPE_BYTES:
	wire_format.WIRETYPE_LENGTH_DELIMITED,
	_FieldDescriptor.TYPE_UINT32: wire_format.WIRETYPE_VARINT,
	_FieldDescriptor.TYPE_ENUM: wire_format.WIRETYPE_VARINT,
	_FieldDescriptor.TYPE_SFIXED32: wire_format.WIRETYPE_FIXED32,
	_FieldDescriptor.TYPE_SFIXED64: wire_format.WIRETYPE_FIXED64,
	_FieldDescriptor.TYPE_SINT32: wire_format.WIRETYPE_VARINT,
	_FieldDescriptor.TYPE_SINT64: wire_format.WIRETYPE_VARINT,
	}