value_or.cpp 641 B

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  1. // Copyright Louis Dionne 2013-2017
  2. // Distributed under the Boost Software License, Version 1.0.
  3. // (See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
  4. #include <boost/hana/assert.hpp>
  5. #include <boost/hana/equal.hpp>
  6. #include <boost/hana/optional.hpp>
  7. #include <laws/base.hpp>
  8. namespace hana = boost::hana;
  9. using hana::test::ct_eq;
  10. struct undefined { };
  11. int main() {
  12. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  13. hana::nothing.value_or(ct_eq<3>{}),
  14. ct_eq<3>{}
  15. ));
  16. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  17. hana::just(ct_eq<4>{}).value_or(undefined{}),
  18. ct_eq<4>{}
  19. ));
  20. }