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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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