112 lines
4.1 KiB
Python
112 lines
4.1 KiB
Python
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# Protocol Buffers - Google's data interchange format
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# Copyright 2008 Google Inc. All rights reserved.
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#
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# Use of this source code is governed by a BSD-style
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# license that can be found in the LICENSE file or at
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# https://developers.google.com/open-source/licenses/bsd
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"""Dynamic Protobuf class creator."""
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from collections import OrderedDict
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import hashlib
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import os
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from google.protobuf import descriptor_pb2
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from google.protobuf import descriptor
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from google.protobuf import descriptor_pool
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from google.protobuf import message_factory
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def _GetMessageFromFactory(pool, full_name):
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"""Get a proto class from the MessageFactory by name.
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Args:
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pool: a descriptor pool.
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full_name: str, the fully qualified name of the proto type.
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Returns:
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A class, for the type identified by full_name.
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Raises:
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KeyError, if the proto is not found in the factory's descriptor pool.
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"""
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proto_descriptor = pool.FindMessageTypeByName(full_name)
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proto_cls = message_factory.GetMessageClass(proto_descriptor)
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return proto_cls
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def MakeSimpleProtoClass(fields, full_name=None, pool=None):
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"""Create a Protobuf class whose fields are basic types.
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Note: this doesn't validate field names!
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Args:
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fields: dict of {name: field_type} mappings for each field in the proto. If
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this is an OrderedDict the order will be maintained, otherwise the
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fields will be sorted by name.
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full_name: optional str, the fully-qualified name of the proto type.
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pool: optional DescriptorPool instance.
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Returns:
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a class, the new protobuf class with a FileDescriptor.
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"""
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pool_instance = pool or descriptor_pool.DescriptorPool()
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if full_name is not None:
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try:
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proto_cls = _GetMessageFromFactory(pool_instance, full_name)
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return proto_cls
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except KeyError:
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# The factory's DescriptorPool doesn't know about this class yet.
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pass
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# Get a list of (name, field_type) tuples from the fields dict. If fields was
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# an OrderedDict we keep the order, but otherwise we sort the field to ensure
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# consistent ordering.
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field_items = fields.items()
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if not isinstance(fields, OrderedDict):
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field_items = sorted(field_items)
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# Use a consistent file name that is unlikely to conflict with any imported
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# proto files.
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fields_hash = hashlib.sha1()
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for f_name, f_type in field_items:
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fields_hash.update(f_name.encode('utf-8'))
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fields_hash.update(str(f_type).encode('utf-8'))
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proto_file_name = fields_hash.hexdigest() + '.proto'
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# If the proto is anonymous, use the same hash to name it.
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if full_name is None:
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full_name = ('net.proto2.python.public.proto_builder.AnonymousProto_' +
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fields_hash.hexdigest())
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try:
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proto_cls = _GetMessageFromFactory(pool_instance, full_name)
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return proto_cls
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except KeyError:
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# The factory's DescriptorPool doesn't know about this class yet.
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pass
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# This is the first time we see this proto: add a new descriptor to the pool.
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pool_instance.Add(
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_MakeFileDescriptorProto(proto_file_name, full_name, field_items))
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return _GetMessageFromFactory(pool_instance, full_name)
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def _MakeFileDescriptorProto(proto_file_name, full_name, field_items):
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"""Populate FileDescriptorProto for MessageFactory's DescriptorPool."""
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package, name = full_name.rsplit('.', 1)
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file_proto = descriptor_pb2.FileDescriptorProto()
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file_proto.name = os.path.join(package.replace('.', '/'), proto_file_name)
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file_proto.package = package
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desc_proto = file_proto.message_type.add()
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desc_proto.name = name
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for f_number, (f_name, f_type) in enumerate(field_items, 1):
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field_proto = desc_proto.field.add()
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field_proto.name = f_name
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# # If the number falls in the reserved range, reassign it to the correct
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# # number after the range.
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if f_number >= descriptor.FieldDescriptor.FIRST_RESERVED_FIELD_NUMBER:
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f_number += (
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descriptor.FieldDescriptor.LAST_RESERVED_FIELD_NUMBER -
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descriptor.FieldDescriptor.FIRST_RESERVED_FIELD_NUMBER + 1)
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field_proto.number = f_number
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field_proto.label = descriptor_pb2.FieldDescriptorProto.LABEL_OPTIONAL
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field_proto.type = f_type
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return file_proto
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