#######################################################################
# Copyright (C) 2017 Shangtong Zhang(zhangshangtong.cpp@gmail.com)    #
# Permission given to modify the code as long as you keep this        #
# declaration at the top                                              #
#######################################################################
# Copyright 2021 Huawei Technologies Co., Ltd
#
# Licensed under the BSD 3-Clause License  (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# https://opensource.org/licenses/BSD-3-Clause
#
# 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.

class ConstantSchedule:
    def __init__(self, val):
        self.val = val

    def __call__(self, steps=1):
        return self.val


class LinearSchedule:
    def __init__(self, start, end=None, steps=None):
        if end is None:
            end = start
            steps = 1
        self.inc = (end - start) / float(steps)
        self.current = start
        self.end = end
        if end > start:
            self.bound = min
        else:
            self.bound = max

    def __call__(self, steps=1):
        val = self.current
        self.current = self.bound(self.current + self.inc * steps, self.end)
        return val