handler_ptr.hpp

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//
// Copyright (c) 2016-2017 Vinnie Falco (vinnie dot falco at gmail dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
// Official repository: https://github.com/boostorg/beast
//

#ifndef BOOST_BEAST_HANDLER_PTR_HPP
#define BOOST_BEAST_HANDLER_PTR_HPP

#include <boost/beast/config.hpp>
#include <boost/beast/core/detail/type_traits.hpp>
#include <atomic>
#include <cstdint>
#include <type_traits>
#include <utility>

namespace boost {
namespace beast {

template<class T, class Handler>
class handler_ptr
{
    struct P
    {
        T* t;
        std::atomic<std::uint16_t> n;

        // There's no way to put the handler anywhere else
        // without exposing ourselves to race conditions
        // and all sorts of ugliness.
        // See:
        //  https://github.com/boostorg/beast/issues/215
        Handler handler;

        template<class DeducedHandler, class... Args>
        P(DeducedHandler&& handler, Args&&... args);
    };

    P* p_;

public:
    using element_type = T;

    using handler_type = Handler;

    handler_ptr& operator=(handler_ptr const&) = delete;

    ~handler_ptr();

    handler_ptr(handler_ptr&& other);

    handler_ptr(handler_ptr const& other);

    template<class... Args>
    handler_ptr(Handler&& handler, Args&&... args);

    template<class... Args>
    handler_ptr(Handler const& handler, Args&&... args);

    handler_type&
    handler() const
    {
        return p_->handler;
    }

    explicit
    operator bool() const
    {
        return p_ && p_->t;
    }

    T*
    get() const
    {
        return p_ ? p_->t : nullptr;
    }

    T&
    operator*() const
    {
        return *p_->t;
    }

    T*
    operator->() const
    {
        return p_->t;
    }

    handler_type
    release_handler();

    template<class... Args>
    void
    invoke(Args&&... args);
};

} // beast
} // boost

#include <boost/beast/core/impl/handler_ptr.ipp>

#endif