88 lines
2.1 KiB
C++
88 lines
2.1 KiB
C++
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// Copyright 2015 Peter Dimov.
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//
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// Distributed under the Boost Software License, Version 1.0.
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//
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// See accompanying file LICENSE_1_0.txt or copy at
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// http://www.boost.org/LICENSE_1_0.txt
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#if defined(_MSC_VER)
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#pragma warning( disable: 4244 ) // 'initializing': conversion from 'int' to 'char', possible loss of data
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#endif
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#include <boost/mp11/tuple.hpp>
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#include <boost/mp11/detail/config.hpp>
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// Technically std::tuple isn't constexpr enabled in C++11, but it works with libstdc++
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#if defined( BOOST_MP11_NO_CONSTEXPR ) || ( !defined( __GLIBCXX__ ) && __cplusplus < 201400L )
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int main() {}
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#else
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#include <tuple>
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#include <array>
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#include <utility>
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struct T1
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{
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int x, y, z;
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constexpr T1( int x = 0, int y = 0, int z = 0 ): x(x), y(y), z(z) {}
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};
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int main()
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{
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using boost::mp11::construct_from_tuple;
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{
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constexpr std::tuple<int, short, char> tp{ 1, 2, 3 };
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constexpr auto r = construct_from_tuple<T1>( tp );
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static_assert( r.x == 1, "r.x == 1" );
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static_assert( r.y == 2, "r.y == 2" );
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static_assert( r.z == 3, "r.z == 3" );
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}
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{
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constexpr std::pair<short, char> tp{ 1, 2 };
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constexpr auto r = construct_from_tuple<T1>( tp );
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static_assert( r.x == 1, "r.x == 1" );
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static_assert( r.y == 2, "r.y == 2" );
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static_assert( r.z == 0, "r.z == 0" );
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}
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{
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constexpr std::array<short, 3> tp{{ 1, 2, 3 }};
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constexpr auto r = construct_from_tuple<T1>( tp );
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static_assert( r.x == 1, "r.x == 1" );
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static_assert( r.y == 2, "r.y == 2" );
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static_assert( r.z == 3, "r.z == 3" );
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}
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#if defined( __clang_major__ ) && __clang_major__ == 3 && __clang_minor__ < 9
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// "error: default initialization of an object of const type 'const std::tuple<>' without a user-provided default constructor"
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#else
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{
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constexpr std::tuple<> tp;
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constexpr auto r = construct_from_tuple<T1>( tp );
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static_assert( r.x == 0, "r.x == 0" );
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static_assert( r.y == 0, "r.y == 0" );
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static_assert( r.z == 0, "r.z == 0" );
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}
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#endif
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}
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#endif
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