1
2 // Copyright 2019 Peter Dimov.
3 //
4 // Distributed under the Boost Software License, Version 1.0.
5 //
6 // See accompanying file LICENSE_1_0.txt or copy at
7 // http://www.boost.org/LICENSE_1_0.txt
8
9
10 #include <boost/mp11/utility.hpp>
11 #include <boost/core/lightweight_test_trait.hpp>
12 #include <cstddef>
13
14 template<class T> using difference_type = typename T::difference_type;
15
16 struct X
17 {
18 };
19
20 struct Y
21 {
22 using difference_type = int;
23 };
24
main()25 int main()
26 {
27 using boost::mp11::mp_eval_or;
28 using boost::mp11::mp_eval_or_q;
29 using boost::mp11::mp_identity;
30 using boost::mp11::mp_quote;
31
32 BOOST_TEST_TRAIT_SAME(mp_eval_or<void, mp_identity>, void);
33 BOOST_TEST_TRAIT_SAME(mp_eval_or<void, mp_identity, int>, mp_identity<int>);
34 BOOST_TEST_TRAIT_SAME(mp_eval_or<void, mp_identity, int, int>, void);
35
36 using Q_identity = mp_quote<mp_identity>;
37
38 BOOST_TEST_TRAIT_SAME(mp_eval_or_q<void, Q_identity>, void);
39 BOOST_TEST_TRAIT_SAME(mp_eval_or_q<void, Q_identity, int>, mp_identity<int>);
40 BOOST_TEST_TRAIT_SAME(mp_eval_or_q<void, Q_identity, int, int>, void);
41
42 BOOST_TEST_TRAIT_SAME(mp_eval_or<std::ptrdiff_t, difference_type, X>, std::ptrdiff_t);
43 BOOST_TEST_TRAIT_SAME(mp_eval_or<std::ptrdiff_t, difference_type, Y>, int);
44
45 using Q_diff_type = mp_quote<difference_type>;
46
47 BOOST_TEST_TRAIT_SAME(mp_eval_or_q<std::ptrdiff_t, Q_diff_type, X>, std::ptrdiff_t);
48 BOOST_TEST_TRAIT_SAME(mp_eval_or_q<std::ptrdiff_t, Q_diff_type, Y>, int);
49
50 return boost::report_errors();
51 }
52