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# Copyright (C) 2016 by the Free Software Foundation, Inc.
#
# This file is part of GNU Mailman.
#
# GNU Mailman is free software: you can redistribute it and/or modify it under
# the terms of the GNU General Public License as published by the Free
# Software Foundation, either version 3 of the License, or (at your option)
# any later version.
#
# GNU Mailman is distributed in the hope that it will be useful, but WITHOUT
# ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
# FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
# more details.
#
# You should have received a copy of the GNU General Public License along with
# GNU Mailman. If not, see <http://www.gnu.org/licenses/>.
"""Some helpers for queries."""
from collections.abc import Sequence
from mailman import public
@public
class QuerySequence(Sequence):
"""A simple wrapper class around database query results.
Use this to provide a sequence-like API around query results, such as
being able to use len() and slicing, where the results objects don't
natively provide them.
"""
def __init__(self, query=None):
super().__init__()
self._query = query
def __len__(self):
return (0 if self._query is None else self._query.count())
def __getitem__(self, index):
if self._query is None:
raise IndexError('index out of range')
return self._query[index]
def __iter__(self):
if self._query is None:
return []
yield from self._query
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