find_if.cpp 1.6 KB

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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/find_if.hpp>
  7. #include <boost/hana/map.hpp>
  8. #include <boost/hana/optional.hpp>
  9. #include <laws/base.hpp>
  10. #include <support/minimal_product.hpp>
  11. namespace hana = boost::hana;
  12. template <int i>
  13. auto key() { return hana::test::ct_eq<i>{}; }
  14. template <int i>
  15. auto val() { return hana::test::ct_eq<-i>{}; }
  16. template <int i, int j>
  17. auto p() { return ::minimal_product(key<i>(), val<j>()); }
  18. int main() {
  19. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  20. hana::find_if(hana::make_map(), hana::equal.to(key<1>())),
  21. hana::nothing
  22. ));
  23. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  24. hana::find_if(hana::make_map(p<1, 1>()), hana::equal.to(key<1>())),
  25. hana::just(val<1>())
  26. ));
  27. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  28. hana::find_if(hana::make_map(p<1, 1>()), hana::equal.to(key<2>())),
  29. hana::nothing
  30. ));
  31. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  32. hana::find_if(hana::make_map(p<1, 1>(), p<2, 2>()), hana::equal.to(key<1>())),
  33. hana::just(val<1>())
  34. ));
  35. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  36. hana::find_if(hana::make_map(p<1, 1>(), p<2, 2>()), hana::equal.to(key<2>())),
  37. hana::just(val<2>())
  38. ));
  39. BOOST_HANA_CONSTANT_CHECK(hana::equal(
  40. hana::find_if(hana::make_map(p<1, 1>(), p<2, 2>()), hana::equal.to(key<3>())),
  41. hana::nothing
  42. ));
  43. }