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# Protocol Buffers - Google's data interchange format
# Copyright 2008 Google Inc. All rights reserved.
# http://code.google.com/p/protobuf/
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# * Redistributions of source code must retain the above copyright
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"""Provides DescriptorPool to use as a container for proto2 descriptors.
The DescriptorPool is used in conjection with a DescriptorDatabase to maintain
a collection of protocol buffer descriptors for use when dynamically creating
message types at runtime.
For most applications protocol buffers should be used via modules generated by
the protocol buffer compiler tool. This should only be used when the type of
protocol buffers used in an application or library cannot be predetermined.
Below is a straightforward example on how to use this class:
pool = DescriptorPool()
file_descriptor_protos = [ ... ]
for file_descriptor_proto in file_descriptor_protos:
pool.Add(file_descriptor_proto)
my_message_descriptor = pool.FindMessageTypeByName('some.package.MessageType')
The message descriptor can be used in conjunction with the message_factory
module in order to create a protocol buffer class that can be encoded and
decoded.
"""
__author__ = 'matthewtoia@google.com (Matt Toia)'
from google.protobuf import descriptor_pb2
from google.protobuf import descriptor
from google.protobuf import descriptor_database
class DescriptorPool(object):
"""A collection of protobufs dynamically constructed by descriptor protos."""
def __init__(self, descriptor_db=None):
"""Initializes a Pool of proto buffs.
The descriptor_db argument to the constructor is provided to allow
specialized file descriptor proto lookup code to be triggered on demand. An
example would be an implementation which will read and compile a file
specified in a call to FindFileByName() and not require the call to Add()
at all. Results from this database will be cached internally here as well.
Args:
descriptor_db: A secondary source of file descriptors.
"""
self._internal_db = descriptor_database.DescriptorDatabase()
self._descriptor_db = descriptor_db
self._descriptors = {}
self._enum_descriptors = {}
self._file_descriptors = {}
def Add(self, file_desc_proto):
"""Adds the FileDescriptorProto and its types to this pool.
Args:
file_desc_proto: The FileDescriptorProto to add.
"""
self._internal_db.Add(file_desc_proto)
def FindFileByName(self, file_name):
"""Gets a FileDescriptor by file name.
Args:
file_name: The path to the file to get a descriptor for.
Returns:
A FileDescriptor for the named file.
Raises:
KeyError: if the file can not be found in the pool.
"""
try:
file_proto = self._internal_db.FindFileByName(file_name)
except KeyError as error:
if self._descriptor_db:
file_proto = self._descriptor_db.FindFileByName(file_name)
else:
raise error
if not file_proto:
raise KeyError('Cannot find a file named %s' % file_name)
return self._ConvertFileProtoToFileDescriptor(file_proto)
def FindFileContainingSymbol(self, symbol):
"""Gets the FileDescriptor for the file containing the specified symbol.
Args:
symbol: The name of the symbol to search for.
Returns:
A FileDescriptor that contains the specified symbol.
Raises:
KeyError: if the file can not be found in the pool.
"""
try:
file_proto = self._internal_db.FindFileContainingSymbol(symbol)
except KeyError as error:
if self._descriptor_db:
file_proto = self._descriptor_db.FindFileContainingSymbol(symbol)
else:
raise error
if not file_proto:
raise KeyError('Cannot find a file containing %s' % symbol)
return self._ConvertFileProtoToFileDescriptor(file_proto)
def FindMessageTypeByName(self, full_name):
"""Loads the named descriptor from the pool.
Args:
full_name: The full name of the descriptor to load.
Returns:
The descriptor for the named type.
"""
full_name = full_name.lstrip('.') # fix inconsistent qualified name formats
if full_name not in self._descriptors:
self.FindFileContainingSymbol(full_name)
return self._descriptors[full_name]
def FindEnumTypeByName(self, full_name):
"""Loads the named enum descriptor from the pool.
Args:
full_name: The full name of the enum descriptor to load.
Returns:
The enum descriptor for the named type.
"""
full_name = full_name.lstrip('.') # fix inconsistent qualified name formats
if full_name not in self._enum_descriptors:
self.FindFileContainingSymbol(full_name)
return self._enum_descriptors[full_name]
def _ConvertFileProtoToFileDescriptor(self, file_proto):
"""Creates a FileDescriptor from a proto or returns a cached copy.
This method also has the side effect of loading all the symbols found in
the file into the appropriate dictionaries in the pool.
Args:
file_proto: The proto to convert.
Returns:
A FileDescriptor matching the passed in proto.
"""
if file_proto.name not in self._file_descriptors:
file_descriptor = descriptor.FileDescriptor(
name=file_proto.name,
package=file_proto.package,
options=file_proto.options,
serialized_pb=file_proto.SerializeToString())
scope = {}
dependencies = list(self._GetDeps(file_proto))
for dependency in dependencies:
dep_desc = self.FindFileByName(dependency.name)
dep_proto = descriptor_pb2.FileDescriptorProto.FromString(
dep_desc.serialized_pb)
package = '.' + dep_proto.package
package_prefix = package + '.'
def _strip_package(symbol):
if symbol.startswith(package_prefix):
return symbol[len(package_prefix):]
return symbol
symbols = list(self._ExtractSymbols(dep_proto.message_type, package))
scope.update(symbols)
scope.update((_strip_package(k), v) for k, v in symbols)
symbols = list(self._ExtractEnums(dep_proto.enum_type, package))
scope.update(symbols)
scope.update((_strip_package(k), v) for k, v in symbols)
for message_type in file_proto.message_type:
message_desc = self._ConvertMessageDescriptor(
message_type, file_proto.package, file_descriptor, scope)
file_descriptor.message_types_by_name[message_desc.name] = message_desc
for enum_type in file_proto.enum_type:
self._ConvertEnumDescriptor(enum_type, file_proto.package,
file_descriptor, None, scope)
for desc_proto in self._ExtractMessages(file_proto.message_type):
self._SetFieldTypes(desc_proto, scope)
for desc_proto in file_proto.message_type:
desc = scope[desc_proto.name]
file_descriptor.message_types_by_name[desc_proto.name] = desc
self.Add(file_proto)
self._file_descriptors[file_proto.name] = file_descriptor
return self._file_descriptors[file_proto.name]
def _ConvertMessageDescriptor(self, desc_proto, package=None, file_desc=None,
scope=None):
"""Adds the proto to the pool in the specified package.
Args:
desc_proto: The descriptor_pb2.DescriptorProto protobuf message.
package: The package the proto should be located in.
file_desc: The file containing this message.
scope: Dict mapping short and full symbols to message and enum types.
Returns:
The added descriptor.
"""
if package:
desc_name = '.'.join((package, desc_proto.name))
else:
desc_name = desc_proto.name
if file_desc is None:
file_name = None
else:
file_name = file_desc.name
if scope is None:
scope = {}
nested = [
self._ConvertMessageDescriptor(nested, desc_name, file_desc, scope)
for nested in desc_proto.nested_type]
enums = [
self._ConvertEnumDescriptor(enum, desc_name, file_desc, None, scope)
for enum in desc_proto.enum_type]
fields = [self._MakeFieldDescriptor(field, desc_name, index)
for index, field in enumerate(desc_proto.field)]
extensions = [self._MakeFieldDescriptor(extension, desc_name, True)
for index, extension in enumerate(desc_proto.extension)]
extension_ranges = [(r.start, r.end) for r in desc_proto.extension_range]
if extension_ranges:
is_extendable = True
else:
is_extendable = False
desc = descriptor.Descriptor(
name=desc_proto.name,
full_name=desc_name,
filename=file_name,
containing_type=None,
fields=fields,
nested_types=nested,
enum_types=enums,
extensions=extensions,
options=desc_proto.options,
is_extendable=is_extendable,
extension_ranges=extension_ranges,
file=file_desc,
serialized_start=None,
serialized_end=None)
for nested in desc.nested_types:
nested.containing_type = desc
for enum in desc.enum_types:
enum.containing_type = desc
scope[desc_proto.name] = desc
scope['.' + desc_name] = desc
self._descriptors[desc_name] = desc
return desc
def _ConvertEnumDescriptor(self, enum_proto, package=None, file_desc=None,
containing_type=None, scope=None):
"""Make a protobuf EnumDescriptor given an EnumDescriptorProto protobuf.
Args:
enum_proto: The descriptor_pb2.EnumDescriptorProto protobuf message.
package: Optional package name for the new message EnumDescriptor.
file_desc: The file containing the enum descriptor.
containing_type: The type containing this enum.
scope: Scope containing available types.
Returns:
The added descriptor
"""
if package:
enum_name = '.'.join((package, enum_proto.name))
else:
enum_name = enum_proto.name
if file_desc is None:
file_name = None
else:
file_name = file_desc.name
values = [self._MakeEnumValueDescriptor(value, index)
for index, value in enumerate(enum_proto.value)]
desc = descriptor.EnumDescriptor(name=enum_proto.name,
full_name=enum_name,
filename=file_name,
file=file_desc,
values=values,
containing_type=containing_type,
options=enum_proto.options)
scope[enum_proto.name] = desc
scope['.%s' % enum_name] = desc
self._enum_descriptors[enum_name] = desc
return desc
def _MakeFieldDescriptor(self, field_proto, message_name, index,
is_extension=False):
"""Creates a field descriptor from a FieldDescriptorProto.
For message and enum type fields, this method will do a look up
in the pool for the appropriate descriptor for that type. If it
is unavailable, it will fall back to the _source function to
create it. If this type is still unavailable, construction will
fail.
Args:
field_proto: The proto describing the field.
message_name: The name of the containing message.
index: Index of the field
is_extension: Indication that this field is for an extension.
Returns:
An initialized FieldDescriptor object
"""
if message_name:
full_name = '.'.join((message_name, field_proto.name))
else:
full_name = field_proto.name
return descriptor.FieldDescriptor(
name=field_proto.name,
full_name=full_name,
index=index,
number=field_proto.number,
type=field_proto.type,
cpp_type=None,
message_type=None,
enum_type=None,
containing_type=None,
label=field_proto.label,
has_default_value=False,
default_value=None,
is_extension=is_extension,
extension_scope=None,
options=field_proto.options)
def _SetFieldTypes(self, desc_proto, scope):
"""Sets the field's type, cpp_type, message_type and enum_type.
Args:
desc_proto: The message descriptor to update.
scope: Enclosing scope of available types.
"""
desc = scope[desc_proto.name]
for field_proto, field_desc in zip(desc_proto.field, desc.fields):
if field_proto.type_name:
type_name = field_proto.type_name
if type_name not in scope:
type_name = '.' + type_name
desc = scope[type_name]
else:
desc = None
if not field_proto.HasField('type'):
if isinstance(desc, descriptor.Descriptor):
field_proto.type = descriptor.FieldDescriptor.TYPE_MESSAGE
else:
field_proto.type = descriptor.FieldDescriptor.TYPE_ENUM
field_desc.cpp_type = descriptor.FieldDescriptor.ProtoTypeToCppProtoType(
field_proto.type)
if (field_proto.type == descriptor.FieldDescriptor.TYPE_MESSAGE
or field_proto.type == descriptor.FieldDescriptor.TYPE_GROUP):
field_desc.message_type = desc
if field_proto.type == descriptor.FieldDescriptor.TYPE_ENUM:
field_desc.enum_type = desc
if field_proto.label == descriptor.FieldDescriptor.LABEL_REPEATED:
field_desc.has_default = False
field_desc.default_value = []
elif field_proto.HasField('default_value'):
field_desc.has_default = True
if (field_proto.type == descriptor.FieldDescriptor.TYPE_DOUBLE or
field_proto.type == descriptor.FieldDescriptor.TYPE_FLOAT):
field_desc.default_value = float(field_proto.default_value)
elif field_proto.type == descriptor.FieldDescriptor.TYPE_STRING:
field_desc.default_value = field_proto.default_value
elif field_proto.type == descriptor.FieldDescriptor.TYPE_BOOL:
field_desc.default_value = field_proto.default_value.lower() == 'true'
elif field_proto.type == descriptor.FieldDescriptor.TYPE_ENUM:
field_desc.default_value = field_desc.enum_type.values_by_name[
field_proto.default_value].index
else:
field_desc.default_value = int(field_proto.default_value)
else:
field_desc.has_default = False
field_desc.default_value = None
field_desc.type = field_proto.type
for nested_type in desc_proto.nested_type:
self._SetFieldTypes(nested_type, scope)
def _MakeEnumValueDescriptor(self, value_proto, index):
"""Creates a enum value descriptor object from a enum value proto.
Args:
value_proto: The proto describing the enum value.
index: The index of the enum value.
Returns:
An initialized EnumValueDescriptor object.
"""
return descriptor.EnumValueDescriptor(
name=value_proto.name,
index=index,
number=value_proto.number,
options=value_proto.options,
type=None)
def _ExtractSymbols(self, desc_protos, package):
"""Pulls out all the symbols from descriptor protos.
Args:
desc_protos: The protos to extract symbols from.
package: The package containing the descriptor type.
Yields:
A two element tuple of the type name and descriptor object.
"""
for desc_proto in desc_protos:
if package:
message_name = '.'.join((package, desc_proto.name))
else:
message_name = desc_proto.name
message_desc = self.FindMessageTypeByName(message_name)
yield (message_name, message_desc)
for symbol in self._ExtractSymbols(desc_proto.nested_type, message_name):
yield symbol
for symbol in self._ExtractEnums(desc_proto.enum_type, message_name):
yield symbol
def _ExtractEnums(self, enum_protos, package):
"""Pulls out all the symbols from enum protos.
Args:
enum_protos: The protos to extract symbols from.
package: The package containing the enum type.
Yields:
A two element tuple of the type name and enum descriptor object.
"""
for enum_proto in enum_protos:
if package:
enum_name = '.'.join((package, enum_proto.name))
else:
enum_name = enum_proto.name
enum_desc = self.FindEnumTypeByName(enum_name)
yield (enum_name, enum_desc)
def _ExtractMessages(self, desc_protos):
"""Pulls out all the message protos from descriptos.
Args:
desc_protos: The protos to extract symbols from.
Yields:
Descriptor protos.
"""
for desc_proto in desc_protos:
yield desc_proto
for message in self._ExtractMessages(desc_proto.nested_type):
yield message
def _GetDeps(self, file_proto):
"""Recursively finds dependencies for file protos.
Args:
file_proto: The proto to get dependencies from.
Yields:
Each direct and indirect dependency.
"""
for dependency in file_proto.dependency:
dep_desc = self.FindFileByName(dependency)
dep_proto = descriptor_pb2.FileDescriptorProto.FromString(
dep_desc.serialized_pb)
yield dep_proto
for parent_dep in self._GetDeps(dep_proto):
yield parent_dep
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