forked-synapse/synapse/util/iterutils.py
2020-01-16 22:25:32 +00:00

36 lines
1.2 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2014-2016 OpenMarket Ltd
# Copyright 2020 The Matrix.org Foundation C.I.C.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from itertools import islice
from typing import Iterable, Iterator, Sequence, Tuple, TypeVar
T = TypeVar("T")
def batch_iter(iterable: Iterable[T], size: int) -> Iterator[Tuple[T]]:
"""batch an iterable up into tuples with a maximum size
Args:
iterable (iterable): the iterable to slice
size (int): the maximum batch size
Returns:
an iterator over the chunks
"""
# make sure we can deal with iterables like lists too
sourceiter = iter(iterable)
# call islice until it returns an empty tuple
return iter(lambda: tuple(islice(sourceiter, size)), ())