/*
 * 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.
 *
 * Copyright 2018 Danny Robson <danny@nerdcruft.net>
 */

#pragma once

#include <utility>


namespace util::functor {
    ///////////////////////////////////////////////////////////////////////////
    /// returns the value provided at construction time regardless of the
    /// arguments supplied in the call operator.
    template <typename ValueT>
    class constant {
    public:
        constant (const ValueT &_value):
            m_value (_value)
        { ; }


        template <typename ...Args>
        ValueT&
        operator() (Args&&...) noexcept
        { return m_value; }


        template <typename ...Args>
        const ValueT&
        operator() (Args&&...) const noexcept
        { return m_value; }


    private:
        ValueT m_value;
    };


    //-------------------------------------------------------------------------
    template <typename ValueT>
    constant (ValueT) -> constant<std::decay_t<ValueT>>;
};