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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
"""Contains _ExtensionDict class to represent extensions.
"""
from google.protobuf.internal import type_checkers
from google.protobuf.descriptor import FieldDescriptor
def _VerifyExtensionHandle(message, extension_handle):
"""Verify that the given extension handle is valid."""
if not isinstance(extension_handle, FieldDescriptor):
raise KeyError('HasExtension() expects an extension handle, got: %s' %
extension_handle)
if not extension_handle.is_extension:
raise KeyError('"%s" is not an extension.' % extension_handle.full_name)
if not extension_handle.containing_type:
raise KeyError('"%s" is missing a containing_type.'
% extension_handle.full_name)
if extension_handle.containing_type is not message.DESCRIPTOR:
raise KeyError('Extension "%s" extends message type "%s", but this '
'message is of type "%s".' %
(extension_handle.full_name,
extension_handle.containing_type.full_name,
message.DESCRIPTOR.full_name))
# TODO: Unify error handling of "unknown extension" crap.
# TODO: Support iteritems()-style iteration over all
# extensions with the "has" bits turned on?
class _ExtensionDict(object):
"""Dict-like container for Extension fields on proto instances.
Note that in all cases we expect extension handles to be
FieldDescriptors.
"""
def __init__(self, extended_message):
"""
Args:
extended_message: Message instance for which we are the Extensions dict.
"""
self._extended_message = extended_message
def __getitem__(self, extension_handle):
"""Returns the current value of the given extension handle."""
_VerifyExtensionHandle(self._extended_message, extension_handle)
result = self._extended_message._fields.get(extension_handle)
if result is not None:
return result
if extension_handle.label == FieldDescriptor.LABEL_REPEATED:
result = extension_handle._default_constructor(self._extended_message)
elif extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
message_type = extension_handle.message_type
if not hasattr(message_type, '_concrete_class'):
# pylint: disable=g-import-not-at-top
from google.protobuf import message_factory
message_factory.GetMessageClass(message_type)
if not hasattr(extension_handle.message_type, '_concrete_class'):
from google.protobuf import message_factory
message_factory.GetMessageClass(extension_handle.message_type)
result = extension_handle.message_type._concrete_class()
try:
result._SetListener(self._extended_message._listener_for_children)
except ReferenceError:
pass
else:
# Singular scalar -- just return the default without inserting into the
# dict.
return extension_handle.default_value
# Atomically check if another thread has preempted us and, if not, swap
# in the new object we just created. If someone has preempted us, we
# take that object and discard ours.
# WARNING: We are relying on setdefault() being atomic. This is true
# in CPython but we haven't investigated others. This warning appears
# in several other locations in this file.
result = self._extended_message._fields.setdefault(
extension_handle, result)
return result
def __eq__(self, other):
if not isinstance(other, self.__class__):
return False
my_fields = self._extended_message.ListFields()
other_fields = other._extended_message.ListFields()
# Get rid of non-extension fields.
my_fields = [field for field in my_fields if field.is_extension]
other_fields = [field for field in other_fields if field.is_extension]
return my_fields == other_fields
def __ne__(self, other):
return not self == other
def __len__(self):
fields = self._extended_message.ListFields()
# Get rid of non-extension fields.
extension_fields = [field for field in fields if field[0].is_extension]
return len(extension_fields)
def __hash__(self):
raise TypeError('unhashable object')
# Note that this is only meaningful for non-repeated, scalar extension
# fields. Note also that we may have to call _Modified() when we do
# successfully set a field this way, to set any necessary "has" bits in the
# ancestors of the extended message.
def __setitem__(self, extension_handle, value):
"""If extension_handle specifies a non-repeated, scalar extension
field, sets the value of that field.
"""
_VerifyExtensionHandle(self._extended_message, extension_handle)
if (extension_handle.label == FieldDescriptor.LABEL_REPEATED or
extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE):
raise TypeError(
'Cannot assign to extension "%s" because it is a repeated or '
'composite type.' % extension_handle.full_name)
# It's slightly wasteful to lookup the type checker each time,
# but we expect this to be a vanishingly uncommon case anyway.
type_checker = type_checkers.GetTypeChecker(extension_handle)
# pylint: disable=protected-access
self._extended_message._fields[extension_handle] = (
type_checker.CheckValue(value))
self._extended_message._Modified()
def __delitem__(self, extension_handle):
self._extended_message.ClearExtension(extension_handle)
def _FindExtensionByName(self, name):
"""Tries to find a known extension with the specified name.
Args:
name: Extension full name.
Returns:
Extension field descriptor.
"""
descriptor = self._extended_message.DESCRIPTOR
extensions = descriptor.file.pool._extensions_by_name[descriptor]
return extensions.get(name, None)
def _FindExtensionByNumber(self, number):
"""Tries to find a known extension with the field number.
Args:
number: Extension field number.
Returns:
Extension field descriptor.
"""
descriptor = self._extended_message.DESCRIPTOR
extensions = descriptor.file.pool._extensions_by_number[descriptor]
return extensions.get(number, None)
def __iter__(self):
# Return a generator over the populated extension fields
return (f[0] for f in self._extended_message.ListFields()
if f[0].is_extension)
def __contains__(self, extension_handle):
_VerifyExtensionHandle(self._extended_message, extension_handle)
if extension_handle not in self._extended_message._fields:
return False
if extension_handle.label == FieldDescriptor.LABEL_REPEATED:
return bool(self._extended_message._fields.get(extension_handle))
if extension_handle.cpp_type == FieldDescriptor.CPPTYPE_MESSAGE:
value = self._extended_message._fields.get(extension_handle)
# pylint: disable=protected-access
return value is not None and value._is_present_in_parent
return True
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