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# 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
"""Dynamic Protobuf class creator."""
from collections import OrderedDict
import hashlib
import os
from google.protobuf import descriptor_pb2
from google.protobuf import descriptor
from google.protobuf import descriptor_pool
from google.protobuf import message_factory
def _GetMessageFromFactory(pool, full_name):
"""Get a proto class from the MessageFactory by name.
Args:
pool: a descriptor pool.
full_name: str, the fully qualified name of the proto type.
Returns:
A class, for the type identified by full_name.
Raises:
KeyError, if the proto is not found in the factory's descriptor pool.
"""
proto_descriptor = pool.FindMessageTypeByName(full_name)
proto_cls = message_factory.GetMessageClass(proto_descriptor)
return proto_cls
def MakeSimpleProtoClass(fields, full_name=None, pool=None):
"""Create a Protobuf class whose fields are basic types.
Note: this doesn't validate field names!
Args:
fields: dict of {name: field_type} mappings for each field in the proto. If
this is an OrderedDict the order will be maintained, otherwise the
fields will be sorted by name.
full_name: optional str, the fully-qualified name of the proto type.
pool: optional DescriptorPool instance.
Returns:
a class, the new protobuf class with a FileDescriptor.
"""
pool_instance = pool or descriptor_pool.DescriptorPool()
if full_name is not None:
try:
proto_cls = _GetMessageFromFactory(pool_instance, full_name)
return proto_cls
except KeyError:
# The factory's DescriptorPool doesn't know about this class yet.
pass
# Get a list of (name, field_type) tuples from the fields dict. If fields was
# an OrderedDict we keep the order, but otherwise we sort the field to ensure
# consistent ordering.
field_items = fields.items()
if not isinstance(fields, OrderedDict):
field_items = sorted(field_items)
# Use a consistent file name that is unlikely to conflict with any imported
# proto files.
fields_hash = hashlib.sha1()
for f_name, f_type in field_items:
fields_hash.update(f_name.encode('utf-8'))
fields_hash.update(str(f_type).encode('utf-8'))
proto_file_name = fields_hash.hexdigest() + '.proto'
# If the proto is anonymous, use the same hash to name it.
if full_name is None:
full_name = ('net.proto2.python.public.proto_builder.AnonymousProto_' +
fields_hash.hexdigest())
try:
proto_cls = _GetMessageFromFactory(pool_instance, full_name)
return proto_cls
except KeyError:
# The factory's DescriptorPool doesn't know about this class yet.
pass
# This is the first time we see this proto: add a new descriptor to the pool.
pool_instance.Add(
_MakeFileDescriptorProto(proto_file_name, full_name, field_items))
return _GetMessageFromFactory(pool_instance, full_name)
def _MakeFileDescriptorProto(proto_file_name, full_name, field_items):
"""Populate FileDescriptorProto for MessageFactory's DescriptorPool."""
package, name = full_name.rsplit('.', 1)
file_proto = descriptor_pb2.FileDescriptorProto()
file_proto.name = os.path.join(package.replace('.', '/'), proto_file_name)
file_proto.package = package
desc_proto = file_proto.message_type.add()
desc_proto.name = name
for f_number, (f_name, f_type) in enumerate(field_items, 1):
field_proto = desc_proto.field.add()
field_proto.name = f_name
# # If the number falls in the reserved range, reassign it to the correct
# # number after the range.
if f_number >= descriptor.FieldDescriptor.FIRST_RESERVED_FIELD_NUMBER:
f_number += (
descriptor.FieldDescriptor.LAST_RESERVED_FIELD_NUMBER -
descriptor.FieldDescriptor.FIRST_RESERVED_FIELD_NUMBER + 1)
field_proto.number = f_number
field_proto.label = descriptor_pb2.FieldDescriptorProto.LABEL_OPTIONAL
field_proto.type = f_type
return file_proto
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