index_if.cpp 879 B

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  1. // Copyright Louis Dionne 2013-2017
  2. // Copyright Jason Rice 2017
  3. // Distributed under the Boost Software License, Version 1.0.
  4. // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  5. #include <boost/hana/core/is_a.hpp>
  6. #include <boost/hana/equal.hpp>
  7. #include <boost/hana/index_if.hpp>
  8. #include <boost/hana/integral_constant.hpp>
  9. #include <boost/hana/optional.hpp>
  10. #include <boost/hana/tuple.hpp>
  11. namespace hana = boost::hana;
  12. constexpr auto xs = hana::make_tuple(0, '1', 2.0);
  13. static_assert(hana::index_if(xs, hana::is_an<int>) == hana::just(hana::size_c<0>), "");
  14. static_assert(hana::index_if(xs, hana::is_a<char>) == hana::just(hana::size_c<1>), "");
  15. static_assert(hana::index_if(xs, hana::is_a<double>) == hana::just(hana::size_c<2>), "");
  16. static_assert(hana::index_if(xs, hana::is_a<hana::tuple_tag>) == hana::nothing, "");
  17. int main() { }