113 lines
3.6 KiB
C++
113 lines
3.6 KiB
C++
/*****************************************************************************
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* \file variant_traits.hpp
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*
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* \brief This internal header provides forward declarations of various
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* variant traits
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*****************************************************************************/
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/*
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The MIT License (MIT)
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Copyright (c) 2020 Matthew Rodusek All rights reserved.
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Permission is hereby granted, free of charge, to any person obtaining a copy
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of this software and associated documentation files (the "Software"), to deal
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in the Software without restriction, including without limitation the rights
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to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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copies of the Software, and to permit persons to whom the Software is
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furnished to do so, subject to the following conditions:
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The above copyright notice and this permission notice shall be included in
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all copies or substantial portions of the Software.
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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SOFTWARE.
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*/
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#ifndef BPSTD_DETAIL_VARIANT_TRAITS_HPP
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#define BPSTD_DETAIL_VARIANT_TRAITS_HPP
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#include "config.hpp"
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#include "variant_fwds.hpp"
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#include "invoke.hpp" // invoke_result
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BPSTD_COMPILER_DIAGNOSTIC_PREAMBLE
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namespace bpstd {
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namespace detail {
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template <typename Variant>
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struct variant_first_type;
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template <bool IsTrivial, typename Type0, typename...Types>
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struct variant_first_type<variant_union<IsTrivial, Type0, Types...>>
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{
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using type = Type0;
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};
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template <bool IsTrivial, typename Type0, typename...Types>
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struct variant_first_type<variant_base<IsTrivial, Type0, Types...>>
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{
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using type = Type0;
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};
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template <typename Type0, typename...Types>
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struct variant_first_type<variant<Type0, Types...>>
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{
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using type = Type0;
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};
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template <typename Variant>
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struct variant_first_type<Variant&>
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{
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using type = typename variant_first_type<Variant>::type&;
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};
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template <typename Variant>
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struct variant_first_type<Variant&&>
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{
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using type = typename variant_first_type<Variant>::type&&;
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};
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template <typename Variant>
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struct variant_first_type<const Variant>
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{
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using type = const typename variant_first_type<Variant>::type;
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};
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template <typename Variant>
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struct variant_first_type<const Variant&>
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{
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using type = const typename variant_first_type<Variant>::type&;
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};
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template <typename Variant>
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struct variant_first_type<const Variant&&>
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{
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using type = const typename variant_first_type<Variant>::type&&;
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};
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template <typename Variant>
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using variant_first_type_t = typename variant_first_type<Variant>::type;
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//--------------------------------------------------------------------------
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template <typename Visitor, typename...Variants>
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struct variant_visitor_invoke_result
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: invoke_result<Visitor,variant_first_type_t<Variants>...>{};
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template <typename Visitor, typename...Variants>
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using variant_visitor_invoke_result_t
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= typename variant_visitor_invoke_result<Visitor, Variants...>::type;
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} // namespace detail
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} // namespace bpstd
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BPSTD_COMPILER_DIAGNOSTIC_POSTAMBLE
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#endif /* BPSTD_DETAIL_VARIANT_TRAITS_HPP */
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