/*
 * Copyright 2019, Intel Corporation
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *
 *     * 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.
 *
 *     * Neither the name of the copyright holder nor the names of its
 *       contributors may be used to endorse or promote products derived
 *       from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "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 THE COPYRIGHT
 * OWNER 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.
 */

/**
 * @file
 * Commonly used SFINAE helpers.
 */

#ifndef LIBPMEMOBJ_CPP_TEMPLATE_HELPERS_HPP
#define LIBPMEMOBJ_CPP_TEMPLATE_HELPERS_HPP

#include <type_traits>

namespace pmem
{

namespace detail
{

template <typename... Ts>
struct make_void {
	typedef void type;
};
template <typename... Ts>
using void_t = typename make_void<Ts...>::type;

/* Generic SFINAE helper for expression checks, based on the idea demonstrated
 * in ISO C++ paper n4502 */
template <typename T, typename, template <typename> class... Checks>
struct supports_impl {
	using type = std::false_type;
};
template <typename T, template <typename> class... Checks>
struct supports_impl<T, void_t<Checks<T>...>, Checks...> {
	using type = std::true_type;
};

template <typename T, template <typename> class... Checks>
using supports = typename supports_impl<T, void, Checks...>::type;

} /* namespace detail */

} /* namespace pmem */

#endif /* LIBPMEMOBJ_CPP_TEMPLATE_HELPERS_HPP */
