# Protocol Buffers - Google's data interchange format
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# https://developers.google.com/protocol-buffers/
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"""Provides a container for DescriptorProtos."""
__author__ = 'matthewtoia@google.com (Matt Toia)'
class Error(Exception):
pass
class DescriptorDatabaseConflictingDefinitionError(Error):
"""Raised when a proto is added with the same name & different descriptor."""
class DescriptorDatabase(object):
"""A container accepting FileDescriptorProtos and maps DescriptorProtos."""
def __init__(self):
self._file_desc_protos_by_file = {}
self._file_desc_protos_by_symbol = {}
def Add(self, file_desc_proto):
"""Adds the FileDescriptorProto and its types to this database.
Args:
file_desc_proto: The FileDescriptorProto to add.
Raises:
DescriptorDatabaseException: if an attempt is made to add a proto
with the same name but different definition than an exisiting
proto in the database.
"""
proto_name = file_desc_proto.name
if proto_name not in self._file_desc_protos_by_file:
self._file_desc_protos_by_file[proto_name] = file_desc_proto
elif self._file_desc_protos_by_file[proto_name] != file_desc_proto:
raise DescriptorDatabaseConflictingDefinitionError(
'%s already added, but with different descriptor.' % proto_name)
package = file_desc_proto.package
for message in file_desc_proto.message_type:
self._file_desc_protos_by_symbol.update(
(name, file_desc_proto) for name in _ExtractSymbols(message, package))
for enum in file_desc_proto.enum_type:
self._file_desc_protos_by_symbol[
'.'.join((package, enum.name))] = file_desc_proto
def FindFileByName(self, name):
"""Finds the file descriptor proto by file name.
Typically the file name is a relative path ending to a .proto file. The
proto with the given name will have to have been added to this database
using the Add method or else an error will be raised.
Args:
name: The file name to find.
Returns:
The file descriptor proto matching the name.
Raises:
KeyError if no file by the given name was added.
"""
return self._file_desc_protos_by_file[name]
def FindFileContainingSymbol(self, symbol):
"""Finds the file descriptor proto containing the specified symbol.
The symbol should be a fully qualified name including the file descriptor's
package and any containing messages. Some examples:
'some.package.name.Message'
'some.package.name.Message.NestedEnum'
The file descriptor proto containing the specified symbol must be added to
this database using the Add method or else an error will be raised.
Args:
symbol: The fully qualified symbol name.
Returns:
The file descriptor proto containing the symbol.
Raises:
KeyError if no file contains the specified symbol.
"""
return self._file_desc_protos_by_symbol[symbol]
def _ExtractSymbols(desc_proto, package):
"""Pulls out all the symbols from a descriptor proto.
Args:
desc_proto: The proto to extract symbols from.
package: The package containing the descriptor type.
Yields:
The fully qualified name found in the descriptor.
"""
message_name = '.'.join((package, desc_proto.name))
yield message_name
for nested_type in desc_proto.nested_type:
for symbol in _ExtractSymbols(nested_type, message_name):
yield symbol
for enum_type in desc_proto.enum_type:
yield '.'.join((message_name, enum_type.name))
