protobuf-src 2.1.1+27.1

# 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

"""Contains routines for printing protocol messages in JSON format.

Simple usage example:

  # Create a proto object and serialize it to a json format string.
  message = my_proto_pb2.MyMessage(foo='bar')
  json_string = json_format.MessageToJson(message)

  # Parse a json format string to proto object.
  message = json_format.Parse(json_string, my_proto_pb2.MyMessage())
"""

__author__ = 'jieluo@google.com (Jie Luo)'


import base64
from collections import OrderedDict
import json
import math
from operator import methodcaller
import re

from google.protobuf import descriptor
from google.protobuf import message_factory
from google.protobuf import symbol_database
from google.protobuf.internal import type_checkers


_INT_TYPES = frozenset([
    descriptor.FieldDescriptor.CPPTYPE_INT32,
    descriptor.FieldDescriptor.CPPTYPE_UINT32,
    descriptor.FieldDescriptor.CPPTYPE_INT64,
    descriptor.FieldDescriptor.CPPTYPE_UINT64,
])
_INT64_TYPES = frozenset([
    descriptor.FieldDescriptor.CPPTYPE_INT64,
    descriptor.FieldDescriptor.CPPTYPE_UINT64,
])
_FLOAT_TYPES = frozenset([
    descriptor.FieldDescriptor.CPPTYPE_FLOAT,
    descriptor.FieldDescriptor.CPPTYPE_DOUBLE,
])
_INFINITY = 'Infinity'
_NEG_INFINITY = '-Infinity'
_NAN = 'NaN'

_UNPAIRED_SURROGATE_PATTERN = re.compile(
    '[\ud800-\udbff](?![\udc00-\udfff])|(?<![\ud800-\udbff])[\udc00-\udfff]'
)

_VALID_EXTENSION_NAME = re.compile(r'\[[a-zA-Z0-9\._]*\]$')


class Error(Exception):
  """Top-level module error for json_format."""


class SerializeToJsonError(Error):
  """Thrown if serialization to JSON fails."""


class ParseError(Error):
  """Thrown in case of parsing error."""


class EnumStringValueParseError(ParseError):
  """Thrown if unknown string enum value is encountered.
  This exception is suppressed if ignore_unknown_fields is set.
  """


def MessageToJson(
    message,
    preserving_proto_field_name=False,
    indent=2,
    sort_keys=False,
    use_integers_for_enums=False,
    descriptor_pool=None,
    float_precision=None,
    ensure_ascii=True,
    always_print_fields_with_no_presence=False,
):
  """Converts protobuf message to JSON format.

  Args:
    message: The protocol buffers message instance to serialize.
    always_print_fields_with_no_presence: If True, fields without
      presence (implicit presence scalars, repeated fields, and map fields) will
      always be serialized. Any field that supports presence is not affected by
      this option (including singular message fields and oneof fields).
    preserving_proto_field_name: If True, use the original proto field names as
      defined in the .proto file. If False, convert the field names to
      lowerCamelCase.
    indent: The JSON object will be pretty-printed with this indent level. An
      indent level of 0 or negative will only insert newlines. If the indent
      level is None, no newlines will be inserted.
    sort_keys: If True, then the output will be sorted by field names.
    use_integers_for_enums: If true, print integers instead of enum names.
    descriptor_pool: A Descriptor Pool for resolving types. If None use the
      default.
    float_precision: If set, use this to specify float field valid digits.
    ensure_ascii: If True, strings with non-ASCII characters are escaped. If
      False, Unicode strings are returned unchanged.

  Returns:
    A string containing the JSON formatted protocol buffer message.
  """
  printer = _Printer(
      preserving_proto_field_name,
      use_integers_for_enums,
      descriptor_pool,
      float_precision,
      always_print_fields_with_no_presence
  )
  return printer.ToJsonString(message, indent, sort_keys, ensure_ascii)


def MessageToDict(
    message,
    always_print_fields_with_no_presence=False,
    preserving_proto_field_name=False,
    use_integers_for_enums=False,
    descriptor_pool=None,
    float_precision=None,
):
  """Converts protobuf message to a dictionary.

  When the dictionary is encoded to JSON, it conforms to proto3 JSON spec.

  Args:
    message: The protocol buffers message instance to serialize.
    always_print_fields_with_no_presence: If True, fields without
      presence (implicit presence scalars, repeated fields, and map fields) will
      always be serialized. Any field that supports presence is not affected by
      this option (including singular message fields and oneof fields).
    preserving_proto_field_name: If True, use the original proto field names as
      defined in the .proto file. If False, convert the field names to
      lowerCamelCase.
    use_integers_for_enums: If true, print integers instead of enum names.
    descriptor_pool: A Descriptor Pool for resolving types. If None use the
      default.
    float_precision: If set, use this to specify float field valid digits.

  Returns:
    A dict representation of the protocol buffer message.
  """
  printer = _Printer(
      preserving_proto_field_name,
      use_integers_for_enums,
      descriptor_pool,
      float_precision,
      always_print_fields_with_no_presence,
  )
  # pylint: disable=protected-access
  return printer._MessageToJsonObject(message)


def _IsMapEntry(field):
  return (
      field.type == descriptor.FieldDescriptor.TYPE_MESSAGE
      and field.message_type.has_options
      and field.message_type.GetOptions().map_entry
  )


class _Printer(object):
  """JSON format printer for protocol message."""

  def __init__(
      self,
      preserving_proto_field_name=False,
      use_integers_for_enums=False,
      descriptor_pool=None,
      float_precision=None,
      always_print_fields_with_no_presence=False,
  ):
    self.always_print_fields_with_no_presence = (
        always_print_fields_with_no_presence
    )
    self.preserving_proto_field_name = preserving_proto_field_name
    self.use_integers_for_enums = use_integers_for_enums
    self.descriptor_pool = descriptor_pool
    if float_precision:
      self.float_format = '.{}g'.format(float_precision)
    else:
      self.float_format = None

  def ToJsonString(self, message, indent, sort_keys, ensure_ascii):
    js = self._MessageToJsonObject(message)
    return json.dumps(
        js, indent=indent, sort_keys=sort_keys, ensure_ascii=ensure_ascii
    )

  def _MessageToJsonObject(self, message):
    """Converts message to an object according to Proto3 JSON Specification."""
    message_descriptor = message.DESCRIPTOR
    full_name = message_descriptor.full_name
    if _IsWrapperMessage(message_descriptor):
      return self._WrapperMessageToJsonObject(message)
    if full_name in _WKTJSONMETHODS:
      return methodcaller(_WKTJSONMETHODS[full_name][0], message)(self)
    js = {}
    return self._RegularMessageToJsonObject(message, js)

  def _RegularMessageToJsonObject(self, message, js):
    """Converts normal message according to Proto3 JSON Specification."""
    fields = message.ListFields()

    try:
      for field, value in fields:
        if self.preserving_proto_field_name:
          name = field.name
        else:
          name = field.json_name
        if _IsMapEntry(field):
          # Convert a map field.
          v_field = field.message_type.fields_by_name['value']
          js_map = {}
          for key in value:
            if isinstance(key, bool):
              if key:
                recorded_key = 'true'
              else:
                recorded_key = 'false'
            else:
              recorded_key = str(key)
            js_map[recorded_key] = self._FieldToJsonObject(v_field, value[key])
          js[name] = js_map
        elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
          # Convert a repeated field.
          js[name] = [self._FieldToJsonObject(field, k) for k in value]
        elif field.is_extension:
          name = '[%s]' % field.full_name
          js[name] = self._FieldToJsonObject(field, value)
        else:
          js[name] = self._FieldToJsonObject(field, value)

      # Serialize default value if including_default_value_fields is True.
      if (
          self.always_print_fields_with_no_presence
      ):
        message_descriptor = message.DESCRIPTOR
        for field in message_descriptor.fields:

          # always_print_fields_with_no_presence doesn't apply to
          # any field which supports presence.
          if (
              self.always_print_fields_with_no_presence
              and field.has_presence
          ):
            continue

          if self.preserving_proto_field_name:
            name = field.name
          else:
            name = field.json_name
          if name in js:
            # Skip the field which has been serialized already.
            continue
          if _IsMapEntry(field):
            js[name] = {}
          elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
            js[name] = []
          else:
            js[name] = self._FieldToJsonObject(field, field.default_value)

    except ValueError as e:
      raise SerializeToJsonError(
          'Failed to serialize {0} field: {1}.'.format(field.name, e)
      ) from e

    return js

  def _FieldToJsonObject(self, field, value):
    """Converts field value according to Proto3 JSON Specification."""
    if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
      return self._MessageToJsonObject(value)
    elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM:
      if self.use_integers_for_enums:
        return value
      if field.enum_type.full_name == 'google.protobuf.NullValue':
        return None
      enum_value = field.enum_type.values_by_number.get(value, None)
      if enum_value is not None:
        return enum_value.name
      else:
        if field.enum_type.is_closed:
          raise SerializeToJsonError(
              'Enum field contains an integer value '
              'which can not mapped to an enum value.'
          )
        else:
          return value
    elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
      if field.type == descriptor.FieldDescriptor.TYPE_BYTES:
        # Use base64 Data encoding for bytes
        return base64.b64encode(value).decode('utf-8')
      else:
        return str(value)
    elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
      return bool(value)
    elif field.cpp_type in _INT64_TYPES:
      return str(value)
    elif field.cpp_type in _FLOAT_TYPES:
      if math.isinf(value):
        if value < 0.0:
          return _NEG_INFINITY
        else:
          return _INFINITY
      if math.isnan(value):
        return _NAN
      if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_FLOAT:
        if self.float_format:
          return float(format(value, self.float_format))
        else:
          return type_checkers.ToShortestFloat(value)

    return value

  def _AnyMessageToJsonObject(self, message):
    """Converts Any message according to Proto3 JSON Specification."""
    if not message.ListFields():
      return {}
    # Must print @type first, use OrderedDict instead of {}
    js = OrderedDict()
    type_url = message.type_url
    js['@type'] = type_url
    sub_message = _CreateMessageFromTypeUrl(type_url, self.descriptor_pool)
    sub_message.ParseFromString(message.value)
    message_descriptor = sub_message.DESCRIPTOR
    full_name = message_descriptor.full_name
    if _IsWrapperMessage(message_descriptor):
      js['value'] = self._WrapperMessageToJsonObject(sub_message)
      return js
    if full_name in _WKTJSONMETHODS:
      js['value'] = methodcaller(_WKTJSONMETHODS[full_name][0], sub_message)(
          self
      )
      return js
    return self._RegularMessageToJsonObject(sub_message, js)

  def _GenericMessageToJsonObject(self, message):
    """Converts message according to Proto3 JSON Specification."""
    # Duration, Timestamp and FieldMask have ToJsonString method to do the
    # convert. Users can also call the method directly.
    return message.ToJsonString()

  def _ValueMessageToJsonObject(self, message):
    """Converts Value message according to Proto3 JSON Specification."""
    which = message.WhichOneof('kind')
    # If the Value message is not set treat as null_value when serialize
    # to JSON. The parse back result will be different from original message.
    if which is None or which == 'null_value':
      return None
    if which == 'list_value':
      return self._ListValueMessageToJsonObject(message.list_value)
    if which == 'number_value':
      value = message.number_value
      if math.isinf(value):
        raise ValueError(
            'Fail to serialize Infinity for Value.number_value, '
            'which would parse as string_value'
        )
      if math.isnan(value):
        raise ValueError(
            'Fail to serialize NaN for Value.number_value, '
            'which would parse as string_value'
        )
    else:
      value = getattr(message, which)
    oneof_descriptor = message.DESCRIPTOR.fields_by_name[which]
    return self._FieldToJsonObject(oneof_descriptor, value)

  def _ListValueMessageToJsonObject(self, message):
    """Converts ListValue message according to Proto3 JSON Specification."""
    return [self._ValueMessageToJsonObject(value) for value in message.values]

  def _StructMessageToJsonObject(self, message):
    """Converts Struct message according to Proto3 JSON Specification."""
    fields = message.fields
    ret = {}
    for key in fields:
      ret[key] = self._ValueMessageToJsonObject(fields[key])
    return ret

  def _WrapperMessageToJsonObject(self, message):
    return self._FieldToJsonObject(
        message.DESCRIPTOR.fields_by_name['value'], message.value
    )


def _IsWrapperMessage(message_descriptor):
  return message_descriptor.file.name == 'google/protobuf/wrappers.proto'


def _DuplicateChecker(js):
  result = {}
  for name, value in js:
    if name in result:
      raise ParseError('Failed to load JSON: duplicate key {0}.'.format(name))
    result[name] = value
  return result


def _CreateMessageFromTypeUrl(type_url, descriptor_pool):
  """Creates a message from a type URL."""
  db = symbol_database.Default()
  pool = db.pool if descriptor_pool is None else descriptor_pool
  type_name = type_url.split('/')[-1]
  try:
    message_descriptor = pool.FindMessageTypeByName(type_name)
  except KeyError as e:
    raise TypeError(
        'Can not find message descriptor by type_url: {0}'.format(type_url)
    ) from e
  message_class = message_factory.GetMessageClass(message_descriptor)
  return message_class()


def Parse(
    text,
    message,
    ignore_unknown_fields=False,
    descriptor_pool=None,
    max_recursion_depth=100,
):
  """Parses a JSON representation of a protocol message into a message.

  Args:
    text: Message JSON representation.
    message: A protocol buffer message to merge into.
    ignore_unknown_fields: If True, do not raise errors for unknown fields.
    descriptor_pool: A Descriptor Pool for resolving types. If None use the
      default.
    max_recursion_depth: max recursion depth of JSON message to be deserialized.
      JSON messages over this depth will fail to be deserialized. Default value
      is 100.

  Returns:
    The same message passed as argument.

  Raises::
    ParseError: On JSON parsing problems.
  """
  if not isinstance(text, str):
    text = text.decode('utf-8')
  try:
    js = json.loads(text, object_pairs_hook=_DuplicateChecker)
  except ValueError as e:
    raise ParseError('Failed to load JSON: {0}.'.format(str(e))) from e
  return ParseDict(
      js, message, ignore_unknown_fields, descriptor_pool, max_recursion_depth
  )


def ParseDict(
    js_dict,
    message,
    ignore_unknown_fields=False,
    descriptor_pool=None,
    max_recursion_depth=100,
):
  """Parses a JSON dictionary representation into a message.

  Args:
    js_dict: Dict representation of a JSON message.
    message: A protocol buffer message to merge into.
    ignore_unknown_fields: If True, do not raise errors for unknown fields.
    descriptor_pool: A Descriptor Pool for resolving types. If None use the
      default.
    max_recursion_depth: max recursion depth of JSON message to be deserialized.
      JSON messages over this depth will fail to be deserialized. Default value
      is 100.

  Returns:
    The same message passed as argument.
  """
  parser = _Parser(ignore_unknown_fields, descriptor_pool, max_recursion_depth)
  parser.ConvertMessage(js_dict, message, '')
  return message


_INT_OR_FLOAT = (int, float)


class _Parser(object):
  """JSON format parser for protocol message."""

  def __init__(
      self, ignore_unknown_fields, descriptor_pool, max_recursion_depth
  ):
    self.ignore_unknown_fields = ignore_unknown_fields
    self.descriptor_pool = descriptor_pool
    self.max_recursion_depth = max_recursion_depth
    self.recursion_depth = 0

  def ConvertMessage(self, value, message, path):
    """Convert a JSON object into a message.

    Args:
      value: A JSON object.
      message: A WKT or regular protocol message to record the data.
      path: parent path to log parse error info.

    Raises:
      ParseError: In case of convert problems.
    """
    self.recursion_depth += 1
    if self.recursion_depth > self.max_recursion_depth:
      raise ParseError(
          'Message too deep. Max recursion depth is {0}'.format(
              self.max_recursion_depth
          )
      )
    message_descriptor = message.DESCRIPTOR
    full_name = message_descriptor.full_name
    if not path:
      path = message_descriptor.name
    if _IsWrapperMessage(message_descriptor):
      self._ConvertWrapperMessage(value, message, path)
    elif full_name in _WKTJSONMETHODS:
      methodcaller(_WKTJSONMETHODS[full_name][1], value, message, path)(self)
    else:
      self._ConvertFieldValuePair(value, message, path)
    self.recursion_depth -= 1

  def _ConvertFieldValuePair(self, js, message, path):
    """Convert field value pairs into regular message.

    Args:
      js: A JSON object to convert the field value pairs.
      message: A regular protocol message to record the data.
      path: parent path to log parse error info.

    Raises:
      ParseError: In case of problems converting.
    """
    names = []
    message_descriptor = message.DESCRIPTOR
    fields_by_json_name = dict(
        (f.json_name, f) for f in message_descriptor.fields
    )
    for name in js:
      try:
        field = fields_by_json_name.get(name, None)
        if not field:
          field = message_descriptor.fields_by_name.get(name, None)
        if not field and _VALID_EXTENSION_NAME.match(name):
          if not message_descriptor.is_extendable:
            raise ParseError(
                'Message type {0} does not have extensions at {1}'.format(
                    message_descriptor.full_name, path
                )
            )
          identifier = name[1:-1]  # strip [] brackets
          # pylint: disable=protected-access
          field = message.Extensions._FindExtensionByName(identifier)
          # pylint: enable=protected-access
          if not field:
            # Try looking for extension by the message type name, dropping the
            # field name following the final . separator in full_name.
            identifier = '.'.join(identifier.split('.')[:-1])
            # pylint: disable=protected-access
            field = message.Extensions._FindExtensionByName(identifier)
            # pylint: enable=protected-access
        if not field:
          if self.ignore_unknown_fields:
            continue
          raise ParseError(
              (
                  'Message type "{0}" has no field named "{1}" at "{2}".\n'
                  ' Available Fields(except extensions): "{3}"'
              ).format(
                  message_descriptor.full_name,
                  name,
                  path,
                  [f.json_name for f in message_descriptor.fields],
              )
          )
        if name in names:
          raise ParseError(
              'Message type "{0}" should not have multiple '
              '"{1}" fields at "{2}".'.format(
                  message.DESCRIPTOR.full_name, name, path
              )
          )
        names.append(name)
        value = js[name]
        # Check no other oneof field is parsed.
        if field.containing_oneof is not None and value is not None:
          oneof_name = field.containing_oneof.name
          if oneof_name in names:
            raise ParseError(
                'Message type "{0}" should not have multiple '
                '"{1}" oneof fields at "{2}".'.format(
                    message.DESCRIPTOR.full_name, oneof_name, path
                )
            )
          names.append(oneof_name)

        if value is None:
          if (
              field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE
              and field.message_type.full_name == 'google.protobuf.Value'
          ):
            sub_message = getattr(message, field.name)
            sub_message.null_value = 0
          elif (
              field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM
              and field.enum_type.full_name == 'google.protobuf.NullValue'
          ):
            setattr(message, field.name, 0)
          else:
            message.ClearField(field.name)
          continue

        # Parse field value.
        if _IsMapEntry(field):
          message.ClearField(field.name)
          self._ConvertMapFieldValue(
              value, message, field, '{0}.{1}'.format(path, name)
          )
        elif field.label == descriptor.FieldDescriptor.LABEL_REPEATED:
          message.ClearField(field.name)
          if not isinstance(value, list):
            raise ParseError(
                'repeated field {0} must be in [] which is {1} at {2}'.format(
                    name, value, path
                )
            )
          if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
            # Repeated message field.
            for index, item in enumerate(value):
              sub_message = getattr(message, field.name).add()
              # None is a null_value in Value.
              if (
                  item is None
                  and sub_message.DESCRIPTOR.full_name
                  != 'google.protobuf.Value'
              ):
                raise ParseError(
                    'null is not allowed to be used as an element'
                    ' in a repeated field at {0}.{1}[{2}]'.format(
                        path, name, index
                    )
                )
              self.ConvertMessage(
                  item, sub_message, '{0}.{1}[{2}]'.format(path, name, index)
              )
          else:
            # Repeated scalar field.
            for index, item in enumerate(value):
              if item is None:
                raise ParseError(
                    'null is not allowed to be used as an element'
                    ' in a repeated field at {0}.{1}[{2}]'.format(
                        path, name, index
                    )
                )
              self._ConvertAndAppendScalar(
                message, field, item, '{0}.{1}[{2}]'.format(path, name, index))
        elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
          if field.is_extension:
            sub_message = message.Extensions[field]
          else:
            sub_message = getattr(message, field.name)
          sub_message.SetInParent()
          self.ConvertMessage(value, sub_message, '{0}.{1}'.format(path, name))
        else:
          if field.is_extension:
            self._ConvertAndSetScalarExtension(message, field, value, '{0}.{1}'.format(path, name))
          else:
            self._ConvertAndSetScalar(message, field, value, '{0}.{1}'.format(path, name))
      except ParseError as e:
        if field and field.containing_oneof is None:
          raise ParseError(
              'Failed to parse {0} field: {1}.'.format(name, e)
          ) from e
        else:
          raise ParseError(str(e)) from e
      except ValueError as e:
        raise ParseError(
            'Failed to parse {0} field: {1}.'.format(name, e)
        ) from e
      except TypeError as e:
        raise ParseError(
            'Failed to parse {0} field: {1}.'.format(name, e)
        ) from e

  def _ConvertAnyMessage(self, value, message, path):
    """Convert a JSON representation into Any message."""
    if isinstance(value, dict) and not value:
      return
    try:
      type_url = value['@type']
    except KeyError as e:
      raise ParseError(
          '@type is missing when parsing any message at {0}'.format(path)
      ) from e

    try:
      sub_message = _CreateMessageFromTypeUrl(type_url, self.descriptor_pool)
    except TypeError as e:
      raise ParseError('{0} at {1}'.format(e, path)) from e
    message_descriptor = sub_message.DESCRIPTOR
    full_name = message_descriptor.full_name
    if _IsWrapperMessage(message_descriptor):
      self._ConvertWrapperMessage(
          value['value'], sub_message, '{0}.value'.format(path)
      )
    elif full_name in _WKTJSONMETHODS:
      methodcaller(
          _WKTJSONMETHODS[full_name][1],
          value['value'],
          sub_message,
          '{0}.value'.format(path),
      )(self)
    else:
      del value['@type']
      self._ConvertFieldValuePair(value, sub_message, path)
      value['@type'] = type_url
    # Sets Any message
    message.value = sub_message.SerializeToString()
    message.type_url = type_url

  def _ConvertGenericMessage(self, value, message, path):
    """Convert a JSON representation into message with FromJsonString."""
    # Duration, Timestamp, FieldMask have a FromJsonString method to do the
    # conversion. Users can also call the method directly.
    try:
      message.FromJsonString(value)
    except ValueError as e:
      raise ParseError('{0} at {1}'.format(e, path)) from e

  def _ConvertValueMessage(self, value, message, path):
    """Convert a JSON representation into Value message."""
    if isinstance(value, dict):
      self._ConvertStructMessage(value, message.struct_value, path)
    elif isinstance(value, list):
      self._ConvertListValueMessage(value, message.list_value, path)
    elif value is None:
      message.null_value = 0
    elif isinstance(value, bool):
      message.bool_value = value
    elif isinstance(value, str):
      message.string_value = value
    elif isinstance(value, _INT_OR_FLOAT):
      message.number_value = value
    else:
      raise ParseError(
          'Value {0} has unexpected type {1} at {2}'.format(
              value, type(value), path
          )
      )

  def _ConvertListValueMessage(self, value, message, path):
    """Convert a JSON representation into ListValue message."""
    if not isinstance(value, list):
      raise ParseError(
          'ListValue must be in [] which is {0} at {1}'.format(value, path)
      )
    message.ClearField('values')
    for index, item in enumerate(value):
      self._ConvertValueMessage(
          item, message.values.add(), '{0}[{1}]'.format(path, index)
      )

  def _ConvertStructMessage(self, value, message, path):
    """Convert a JSON representation into Struct message."""
    if not isinstance(value, dict):
      raise ParseError(
          'Struct must be in a dict which is {0} at {1}'.format(value, path)
      )
    # Clear will mark the struct as modified so it will be created even if
    # there are no values.
    message.Clear()
    for key in value:
      self._ConvertValueMessage(
          value[key], message.fields[key], '{0}.{1}'.format(path, key)
      )
    return

  def _ConvertWrapperMessage(self, value, message, path):
    """Convert a JSON representation into Wrapper message."""
    field = message.DESCRIPTOR.fields_by_name['value']
    self._ConvertAndSetScalar(message, field, value, path='{0}.value'.format(path))

  def _ConvertMapFieldValue(self, value, message, field, path):
    """Convert map field value for a message map field.

    Args:
      value: A JSON object to convert the map field value.
      message: A protocol message to record the converted data.
      field: The descriptor of the map field to be converted.
      path: parent path to log parse error info.

    Raises:
      ParseError: In case of convert problems.
    """
    if not isinstance(value, dict):
      raise ParseError(
          'Map field {0} must be in a dict which is {1} at {2}'.format(
              field.name, value, path
          )
      )
    key_field = field.message_type.fields_by_name['key']
    value_field = field.message_type.fields_by_name['value']
    for key in value:
      key_value = _ConvertScalarFieldValue(
          key, key_field, '{0}.key'.format(path), True
      )
      if value_field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_MESSAGE:
        self.ConvertMessage(
            value[key],
            getattr(message, field.name)[key_value],
            '{0}[{1}]'.format(path, key_value),
        )
      else:
        self._ConvertAndSetScalarToMapKey(
            message,
            field,
            key_value,
            value[key],
            path='{0}[{1}]'.format(path, key_value))

  def _ConvertAndSetScalarExtension(self, message, extension_field, js_value, path):
    """Convert scalar from js_value and assign it to message.Extensions[extension_field]."""
    try:
      message.Extensions[extension_field] = _ConvertScalarFieldValue(
          js_value, extension_field, path)
    except EnumStringValueParseError:
      if not self.ignore_unknown_fields:
        raise

  def _ConvertAndSetScalar(self, message, field, js_value, path):
    """Convert scalar from js_value and assign it to message.field."""
    try:
      setattr(
          message,
          field.name,
          _ConvertScalarFieldValue(js_value, field, path))
    except EnumStringValueParseError:
      if not self.ignore_unknown_fields:
        raise

  def _ConvertAndAppendScalar(self, message, repeated_field, js_value, path):
    """Convert scalar from js_value and append it to message.repeated_field."""
    try:
      getattr(message, repeated_field.name).append(
          _ConvertScalarFieldValue(js_value, repeated_field, path))
    except EnumStringValueParseError:
      if not self.ignore_unknown_fields:
        raise

  def _ConvertAndSetScalarToMapKey(self, message, map_field, converted_key, js_value, path):
    """Convert scalar from 'js_value' and add it to message.map_field[converted_key]."""
    try:
      getattr(message, map_field.name)[converted_key] = _ConvertScalarFieldValue(
          js_value, map_field.message_type.fields_by_name['value'], path,
      )
    except EnumStringValueParseError:
      if not self.ignore_unknown_fields:
        raise


def _ConvertScalarFieldValue(value, field, path, require_str=False):
  """Convert a single scalar field value.

  Args:
    value: A scalar value to convert the scalar field value.
    field: The descriptor of the field to convert.
    path: parent path to log parse error info.
    require_str: If True, the field value must be a str.

  Returns:
    The converted scalar field value

  Raises:
    ParseError: In case of convert problems.
    EnumStringValueParseError: In case of unknown enum string value.
  """
  try:
    if field.cpp_type in _INT_TYPES:
      return _ConvertInteger(value)
    elif field.cpp_type in _FLOAT_TYPES:
      return _ConvertFloat(value, field)
    elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_BOOL:
      return _ConvertBool(value, require_str)
    elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_STRING:
      if field.type == descriptor.FieldDescriptor.TYPE_BYTES:
        if isinstance(value, str):
          encoded = value.encode('utf-8')
        else:
          encoded = value
        # Add extra padding '='
        padded_value = encoded + b'=' * (4 - len(encoded) % 4)
        return base64.urlsafe_b64decode(padded_value)
      else:
        # Checking for unpaired surrogates appears to be unreliable,
        # depending on the specific Python version, so we check manually.
        if _UNPAIRED_SURROGATE_PATTERN.search(value):
          raise ParseError('Unpaired surrogate')
        return value
    elif field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_ENUM:
      # Convert an enum value.
      enum_value = field.enum_type.values_by_name.get(value, None)
      if enum_value is None:
        try:
          number = int(value)
          enum_value = field.enum_type.values_by_number.get(number, None)
        except ValueError as e:
          # Since parsing to integer failed and lookup in values_by_name didn't
          # find this name, we have an enum string value which is unknown.
          raise EnumStringValueParseError(
              'Invalid enum value {0} for enum type {1}'.format(
                  value, field.enum_type.full_name
              )
          ) from e
        if enum_value is None:
          if field.enum_type.is_closed:
            raise ParseError(
                'Invalid enum value {0} for enum type {1}'.format(
                    value, field.enum_type.full_name
                )
            )
          else:
            return number
      return enum_value.number
  except EnumStringValueParseError as e:
    raise EnumStringValueParseError('{0} at {1}'.format(e, path)) from e
  except ParseError as e:
    raise ParseError('{0} at {1}'.format(e, path)) from e


def _ConvertInteger(value):
  """Convert an integer.

  Args:
    value: A scalar value to convert.

  Returns:
    The integer value.

  Raises:
    ParseError: If an integer couldn't be consumed.
  """
  if isinstance(value, float) and not value.is_integer():
    raise ParseError("Couldn't parse integer: {0}".format(value))

  if isinstance(value, str) and value.find(' ') != -1:
    raise ParseError('Couldn\'t parse integer: "{0}"'.format(value))

  if isinstance(value, bool):
    raise ParseError(
        'Bool value {0} is not acceptable for integer field'.format(value)
    )

  return int(value)


def _ConvertFloat(value, field):
  """Convert an floating point number."""
  if isinstance(value, float):
    if math.isnan(value):
      raise ParseError('Couldn\'t parse NaN, use quoted "NaN" instead')
    if math.isinf(value):
      if value > 0:
        raise ParseError(
            "Couldn't parse Infinity or value too large, "
            'use quoted "Infinity" instead'
        )
      else:
        raise ParseError(
            "Couldn't parse -Infinity or value too small, "
            'use quoted "-Infinity" instead'
        )
    if field.cpp_type == descriptor.FieldDescriptor.CPPTYPE_FLOAT:
      # pylint: disable=protected-access
      if value > type_checkers._FLOAT_MAX:
        raise ParseError('Float value too large')
      # pylint: disable=protected-access
      if value < type_checkers._FLOAT_MIN:
        raise ParseError('Float value too small')
  if value == 'nan':
    raise ParseError('Couldn\'t parse float "nan", use "NaN" instead')
  try:
    # Assume Python compatible syntax.
    return float(value)
  except ValueError as e:
    # Check alternative spellings.
    if value == _NEG_INFINITY:
      return float('-inf')
    elif value == _INFINITY:
      return float('inf')
    elif value == _NAN:
      return float('nan')
    else:
      raise ParseError("Couldn't parse float: {0}".format(value)) from e


def _ConvertBool(value, require_str):
  """Convert a boolean value.

  Args:
    value: A scalar value to convert.
    require_str: If True, value must be a str.

  Returns:
    The bool parsed.

  Raises:
    ParseError: If a boolean value couldn't be consumed.
  """
  if require_str:
    if value == 'true':
      return True
    elif value == 'false':
      return False
    else:
      raise ParseError('Expected "true" or "false", not {0}'.format(value))

  if not isinstance(value, bool):
    raise ParseError('Expected true or false without quotes')
  return value


_WKTJSONMETHODS = {
    'google.protobuf.Any': ['_AnyMessageToJsonObject', '_ConvertAnyMessage'],
    'google.protobuf.Duration': [
        '_GenericMessageToJsonObject',
        '_ConvertGenericMessage',
    ],
    'google.protobuf.FieldMask': [
        '_GenericMessageToJsonObject',
        '_ConvertGenericMessage',
    ],
    'google.protobuf.ListValue': [
        '_ListValueMessageToJsonObject',
        '_ConvertListValueMessage',
    ],
    'google.protobuf.Struct': [
        '_StructMessageToJsonObject',
        '_ConvertStructMessage',
    ],
    'google.protobuf.Timestamp': [
        '_GenericMessageToJsonObject',
        '_ConvertGenericMessage',
    ],
    'google.protobuf.Value': [
        '_ValueMessageToJsonObject',
        '_ConvertValueMessage',
    ],
}