# Copyright (c) 2016 PaddlePaddle Authors. All Rights Reserved
#
# 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.


def batch(reader, batch_size):
    """
    Create a batch reader.
    :param reader: the data reader to read from.
    :param batch_size: batch_size
    :return: the batch reader.
    """

    def batch_reader():
        r = reader()
        batch = []
        for instance in r:
            batch.append(instance)
            if len(batch) == batch_size:
                yield batch
                batch = []
        if batch:
            yield batch

    return batch_reader