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/ext/std/integral_constant.hpp>
7 #include <boost/hana/find.hpp>
8 #include <boost/hana/find_if.hpp>
9 #include <boost/hana/functional/compose.hpp>
10 #include <boost/hana/integral_constant.hpp>
11 #include <boost/hana/optional.hpp>
12 #include <boost/hana/tuple.hpp>
13 #include <boost/hana/type.hpp>
14
15 #include <type_traits>
16 namespace hana = boost::hana;
17
18
19 // First get the type of the object, and then call the trait on it.
20 constexpr auto is_integral = hana::compose(hana::trait<std::is_integral>, hana::typeid_);
21 constexpr auto is_class = hana::compose(hana::trait<std::is_class>, hana::typeid_);
22
23 static_assert(
24 hana::find_if(hana::make_tuple(1.0, 2, '3'), is_integral)
25 ==
26 hana::just(2)
27 , "");
28
29 BOOST_HANA_CONSTANT_CHECK(
30 hana::find_if(hana::make_tuple(1.0, 2, '3'), is_class)
31 ==
32 hana::nothing
33 );
34
35 BOOST_HANA_CONSTANT_CHECK(
36 hana::find(hana::make_tuple(hana::int_c<1>, hana::char_c<'c'>, hana::type_c<void>), hana::type_c<void>)
37 ==
38 hana::just(hana::type_c<void>)
39 );
40
41 BOOST_HANA_CONSTANT_CHECK(
42 hana::find(hana::make_tuple(hana::int_c<1>, hana::char_c<'c'>, hana::type_c<void>), hana::type_c<int>)
43 ==
44 hana::nothing
45 );
46
main()47 int main() { }
48