# Copyright 2018 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from enum import EnumMeta
from google.protobuf import descriptor_pb2
from google.protobuf.internal.enum_type_wrapper import EnumTypeWrapper
from proto.primitives import ProtoType
[docs]class Field:
"""A representation of a type of field in protocol buffers."""
# Fields are NOT repeated nor maps.
# The RepeatedField overrides this values.
repeated = False
def __init__(
self,
proto_type,
*,
number: int,
message=None,
enum=None,
oneof: str = None,
json_name: str = None,
optional: bool = False
):
# This class is not intended to stand entirely alone;
# data is augmented by the metaclass for Message.
self.mcls_data = None
self.parent = None
# If the proto type sent is an object or a string, it is really
# a message or enum.
if not isinstance(proto_type, int):
# Note: We only support the "shortcut syntax" for enums
# when receiving the actual class.
if isinstance(proto_type, (EnumMeta, EnumTypeWrapper)):
enum = proto_type
proto_type = ProtoType.ENUM
else:
message = proto_type
proto_type = ProtoType.MESSAGE
# Save the direct arguments.
self.number = number
self.proto_type = proto_type
self.message = message
self.enum = enum
self.json_name = json_name
self.optional = optional
self.oneof = oneof
# Once the descriptor is accessed the first time, cache it.
# This is important because in rare cases the message or enum
# types are written later.
self._descriptor = None
@property
def descriptor(self):
"""Return the descriptor for the field."""
if not self._descriptor:
# Resolve the message type, if any, to a string.
type_name = None
if isinstance(self.message, str):
if not self.message.startswith(self.package):
self.message = "{package}.{name}".format(
package=self.package,
name=self.message,
)
type_name = self.message
elif self.message:
type_name = (
self.message.DESCRIPTOR.full_name
if hasattr(self.message, "DESCRIPTOR")
else self.message._meta.full_name
)
elif isinstance(self.enum, str):
if not self.enum.startswith(self.package):
self.enum = "{package}.{name}".format(
package=self.package,
name=self.enum,
)
type_name = self.enum
elif self.enum:
type_name = (
self.enum.DESCRIPTOR.full_name
if hasattr(self.enum, "DESCRIPTOR")
else self.enum._meta.full_name
)
# Set the descriptor.
self._descriptor = descriptor_pb2.FieldDescriptorProto(
name=self.name,
number=self.number,
label=3 if self.repeated else 1,
type=self.proto_type,
type_name=type_name,
json_name=self.json_name,
proto3_optional=self.optional,
)
# Return the descriptor.
return self._descriptor
@property
def name(self) -> str:
"""Return the name of the field."""
return self.mcls_data["name"]
@property
def package(self) -> str:
"""Return the package of the field."""
return self.mcls_data["package"]
@property
def pb_type(self):
"""Return the composite type of the field, or the primitive type if a primitive."""
# For enums, return the Python enum.
if self.enum:
return self.enum
# For primitive fields, we still want to know
# what the type is.
if not self.message:
return self.proto_type
# Return the internal protobuf message.
if hasattr(self.message, "_meta"):
return self.message.pb()
return self.message
[docs]class RepeatedField(Field):
"""A representation of a repeated field in protocol buffers."""
repeated = True
[docs]class MapField(Field):
"""A representation of a map field in protocol buffers."""
def __init__(self, key_type, value_type, *, number: int, message=None, enum=None):
super().__init__(value_type, number=number, message=message, enum=enum)
self.map_key_type = key_type
__all__ = (
"Field",
"MapField",
"RepeatedField",
)