//

// Copyright (c) 2019 Vinnie Falco (vinnie.falco@gmail.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/json

//

#ifndef BOOST_JSON_IMPL_NULL_RESOURCE_IPP

#define BOOST_JSON_IMPL_NULL_RESOURCE_IPP

#include <boost/json/null_resource.hpp>

#include <boost/throw_exception.hpp>

namespace boost {

namespace json {

namespace detail {

/** A resource which always fails.

    This memory resource always throws the exception

    `std::bad_alloc` in calls to `allocate`.

*/

class null_resource final

    : public container::pmr::memory_resource

{

public:

    /// Copy constructor (deleted)

    null_resource(

        null_resource const&) = delete;

    /// Copy assignment (deleted)

    null_resource& operator=(

        null_resource const&) = delete;

    /** Constructor

        This constructs the resource.

        @par Complexity

        Constant.

        @par Exception Safety

        No-throw guarantee.

    */

    /** @{ */

    null_resource() noexcept = default;

protected:

    void*

    do_allocate(

        std::size_t,

        std::size_t) override

    {

        throw_exception( std::bad_alloc(), BOOST_CURRENT_LOCATION );

    }

    void

    do_deallocate(

        void*,

        std::size_t,

        std::size_t) override

    {

        // do nothing

    }

    bool

    do_is_equal(

        memory_resource const& mr

            ) const noexcept override

    {

        return this == &mr;

    }

};

} // detail

container::pmr::memory_resource*

get_null_resource() noexcept

{

    static detail::null_resource mr;

    return &mr;

}

} // namespace json

} // namespace boost

#endif