1// Copyright Louis Dionne 2013-2022
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/concat.hpp>
7#include <boost/hana/equal.hpp>
8#include <boost/hana/optional.hpp>
9
10#include <laws/base.hpp>
11namespace hana = boost::hana;
12using hana::test::ct_eq;
13
14
15int main() {
16 auto rv_nothing = [] { return hana::nothing; }; // rvalue nothing
17
18 BOOST_HANA_CONSTANT_CHECK(hana::equal(
19 hana::concat(rv_nothing(), hana::nothing),
20 hana::nothing
21 ));
22 BOOST_HANA_CONSTANT_CHECK(hana::equal(
23 hana::concat(hana::nothing, rv_nothing()),
24 hana::nothing
25 ));
26 BOOST_HANA_CONSTANT_CHECK(hana::equal(
27 hana::concat(rv_nothing(), rv_nothing()),
28 hana::nothing
29 ));
30 BOOST_HANA_CONSTANT_CHECK(hana::equal(
31 hana::concat(rv_nothing(), hana::just(ct_eq<0>{})),
32 hana::just(ct_eq<0>{})
33 ));
34 BOOST_HANA_CONSTANT_CHECK(hana::equal(
35 hana::concat(hana::just(ct_eq<0>{}), rv_nothing()),
36 hana::just(ct_eq<0>{})
37 ));
38
39 BOOST_HANA_CONSTANT_CHECK(hana::equal(
40 hana::concat(hana::nothing, hana::nothing),
41 hana::nothing
42 ));
43 BOOST_HANA_CONSTANT_CHECK(hana::equal(
44 hana::concat(hana::nothing, hana::just(ct_eq<0>{})),
45 hana::just(ct_eq<0>{})
46 ));
47 BOOST_HANA_CONSTANT_CHECK(hana::equal(
48 hana::concat(hana::just(ct_eq<0>{}), hana::nothing),
49 hana::just(ct_eq<0>{})
50 ));
51 BOOST_HANA_CONSTANT_CHECK(hana::equal(
52 hana::concat(hana::just(ct_eq<0>{}), hana::just(ct_eq<1>{})),
53 hana::just(ct_eq<0>{})
54 ));
55}
56

source code of boost/libs/hana/test/optional/concat.cpp