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#ifndef OPAQUE_TYPE_TRAITS_HPP
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#define OPAQUE_TYPE_TRAITS_HPP
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//
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// Copyright (c) 2015
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// Kyle Markley. All rights reserved.
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//
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are met:
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//
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// 1. Redistributions of source code must retain the above copyright notice,
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// this list of conditions and the following disclaimer.
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// 2. Redistributions in binary form must reproduce the above copyright notice,
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// this list of conditions and the following disclaimer in the documentation
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// and/or other materials provided with the distribution.
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// 3. Neither the name of the author nor the names of any contributors may be
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// used to endorse or promote products derived from this software without
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// specific prior written permission.
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//
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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// ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
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// LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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// CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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// SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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// INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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// CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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// ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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// POSSIBILITY OF SUCH DAMAGE.
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//
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#include <type_traits>
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namespace opaque {
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/// \addtogroup internal
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/// @{
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#ifdef __cpp_lib_void_t
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using std::void_t;
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#else
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// CWG 1558
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template <typename...> struct voider { using type = void; };
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template <typename... T> using void_t = typename voider<T...>::type;
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#endif
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namespace detail {
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template <typename F, typename... Args>
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using functor_result_t = decltype(std::declval<F>()(std::declval<Args>()...));
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template <typename F, typename = void, typename... Args>
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struct functor_well_formed : std::false_type { };
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template <typename F, typename... Args>
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struct functor_well_formed<F, void_t<functor_result_t<F,Args...>>, Args...>
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: std::true_type {
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using result_type = functor_result_t<F,Args...>;
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};
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}
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template <typename F, typename... Args>
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using is_functor_call_well_formed
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= detail::functor_well_formed<F, void, Args...>;
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///
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/// Determine whether a type is decayed
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///
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template <typename T>
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struct is_decayed : std::conditional<
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std::is_same<T, typename std::decay<T>::type>::value,
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std::true_type, std::false_type>::type { };
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///
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/// Determine whether two types are related by inheritance
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///
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template <typename T, typename U>
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struct is_related : std::conditional<
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std::is_base_of<T,U>::value or std::is_base_of<U,T>::value,
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std::true_type, std::false_type>::type { };
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///
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/// Determine whether casting to T from U is free, or creates a new object
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///
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template <typename T, typename U>
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struct is_cast_free : std::conditional<
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std::is_same<T,U>::value or is_related<T,U>::value,
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std::true_type, std::false_type>::type { };
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/// @}
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}
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#endif
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