Source/WTF/wtf/RecursableLambda.h

/*
 * Copyright (C) 2017 Yusuke Suzuki <utatane.tea@gmail.com>. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY APPLE INC. ``AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL APPLE INC. OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
 * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#pragma once

#include <type_traits>

namespace WTF {

template<typename Functor>
class RecursableLambda {
    WTF_MAKE_FAST_ALLOCATED;
public:
    explicit RecursableLambda(Functor&& functor)
        : m_functor(std::forward<Functor>(functor))
    {
    }

    template<typename... Args>
    decltype(auto) operator()(Args&&... args) const
    {
        return m_functor(std::ref(*this), std::forward<Args>(args)...);
    }

private:
    Functor m_functor;
};

template<typename Functor>
decltype(auto) recursableLambda(Functor&& f)
{
    return RecursableLambda<std::decay_t<Functor>>(std::forward<Functor>(f));
}

} // namespace WTF

using WTF::recursableLambda;