libs/hana/test/optional/maybe.cpp

   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
   5 #include <boost/hana/assert.hpp>
   6 #include <boost/hana/equal.hpp>
   7 #include <boost/hana/optional.hpp>
   8
   9 #include <laws/base.hpp>
  10 namespace hana = boost::hana;
  11
  12
  13 struct undefined { };
  14
  15 int main() {
  16     hana::test::_injection<0> f{};
  17     hana::test::ct_eq<2> x{};
  18
  19     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  20         hana::maybe(x, undefined{}, hana::nothing),
  21         x
  22     ));
  23
  24     BOOST_HANA_CONSTANT_CHECK(hana::equal(
  25         hana::maybe(undefined{}, f, hana::just(x)),
  26         f(x)
  27     ));
  28 }