| 1 | // Copyright Louis Dionne 2013-2022 |
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| 2 | // Distributed under the Boost Software License, Version 1.0. |
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| 3 | // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt) |
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| 4 | |
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| 5 | #include <boost/hana/assert.hpp> |
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| 6 | #include <boost/hana/concept/metafunction.hpp> |
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| 7 | #include <boost/hana/equal.hpp> |
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| 8 | #include <boost/hana/not.hpp> |
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| 9 | #include <boost/hana/type.hpp> |
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| 10 | |
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| 11 | #include <type_traits> |
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| 12 | namespace hana = boost::hana; |
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| 13 | |
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| 14 | |
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| 15 | struct x1; struct x2; struct x3; |
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| 16 | struct y1 { }; struct y2 { }; struct y3 { }; |
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| 17 | template <typename ...> struct f { struct type; }; |
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| 18 | |
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| 19 | template <typename F, typename ...T> |
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| 20 | constexpr auto valid_call(F f, T ...t) -> decltype(((void)f(t...)), true) |
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| 21 | { return true; } |
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| 22 | constexpr auto valid_call(...) |
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| 23 | { return false; } |
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| 24 | |
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| 25 | BOOST_HANA_CONSTANT_CHECK(hana::equal( |
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| 26 | hana::metafunction<f>(), |
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| 27 | hana::type_c<f<>::type> |
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| 28 | )); |
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| 29 | |
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| 30 | BOOST_HANA_CONSTANT_CHECK(hana::equal( |
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| 31 | hana::metafunction<f>(hana::type_c<x1>), |
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| 32 | hana::type_c<f<x1>::type> |
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| 33 | )); |
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| 34 | |
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| 35 | BOOST_HANA_CONSTANT_CHECK(hana::equal( |
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| 36 | hana::metafunction<f>(hana::type_c<x1>, hana::type_c<x2>), |
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| 37 | hana::type_c<f<x1, x2>::type> |
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| 38 | )); |
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| 39 | |
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| 40 | BOOST_HANA_CONSTANT_CHECK(hana::equal( |
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| 41 | hana::metafunction<f>(hana::type_c<x1>, hana::type_c<x2>, hana::type_c<x3>), |
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| 42 | hana::type_c<f<x1, x2, x3>::type> |
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| 43 | )); |
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| 44 | |
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| 45 | using F = decltype(hana::metafunction<f>); |
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| 46 | static_assert(std::is_same<F::apply<>, f<>>::value, "" ); |
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| 47 | static_assert(std::is_same<F::apply<x1>, f<x1>>::value, "" ); |
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| 48 | static_assert(std::is_same<F::apply<x1, x2>, f<x1, x2>>::value, "" ); |
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| 49 | static_assert(std::is_same<F::apply<x1, x2, x3>, f<x1, x2, x3>>::value, "" ); |
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| 50 | |
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| 51 | // Make sure we're SFINAE-friendly |
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| 52 | template <typename ...T> struct no_type { }; |
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| 53 | static_assert(!valid_call(hana::metafunction<no_type>), "" ); |
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| 54 | static_assert(!valid_call(hana::metafunction<no_type>, hana::type_c<x1>), "" ); |
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| 55 | |
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| 56 | // Make sure we model the Metafunction concept |
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| 57 | static_assert(hana::Metafunction<decltype(hana::metafunction<f>)>::value, "" ); |
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| 58 | static_assert(hana::Metafunction<decltype(hana::metafunction<f>)&>::value, "" ); |
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| 59 | |
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| 60 | // Make sure metafunction is SFINAE-friendly |
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| 61 | template <typename T> struct not_a_metafunction { }; |
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| 62 | BOOST_HANA_CONSTANT_CHECK(hana::not_( |
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| 63 | hana::is_valid(hana::metafunction<not_a_metafunction>)(hana::type_c<void>) |
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| 64 | )); |
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| 65 | |
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| 66 | |
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| 67 | // Make sure we don't read from a non-constexpr variable |
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| 68 | int main() { |
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| 69 | auto t = hana::type_c<x1>; |
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| 70 | constexpr auto r = hana::metafunction<f>(t); |
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| 71 | (void)r; |
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| 72 | } |
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| 73 | |
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