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/bool.hpp>
6 #include <boost/hana/eval_if.hpp>
7 #include <boost/hana/fwd/not.hpp>
8 #include <boost/hana/fwd/while.hpp>
9 #include <boost/hana/if.hpp>
10 namespace hana = boost::hana;
11
12
13 // This test makes sure that if_ can be used with non-copyable branches.
14
15 template <bool Value>
16 struct Boolean { };
17
18 namespace boost { namespace hana {
19 template <bool Value>
20 struct while_impl<Boolean<Value>> {
21 // Not implemented
22 };
23
24 template <bool Value>
25 struct not_impl<Boolean<Value>> {
26 // Not implemented
27 };
28
29 template <bool Value>
30 struct eval_if_impl<Boolean<Value>> {
31 template <typename Cond, typename Then, typename Else>
applyboost::hana::eval_if_impl32 static constexpr decltype(auto) apply(Cond const&, Then&& t, Else&& e) {
33 return hana::eval_if(hana::bool_c<Value>, static_cast<Then&&>(t),
34 static_cast<Else&&>(e));
35 }
36 };
37 }}
38
39 template <int v>
40 struct NonCopyable {
41 static constexpr int value = v;
42 NonCopyable() = default;
43 NonCopyable(NonCopyable const&) = delete;
44 NonCopyable(NonCopyable&&) = default;
45
46 NonCopyable& operator=(NonCopyable const&) = delete;
47 NonCopyable& operator=(NonCopyable&&) = default;
48 };
49
50 static_assert(hana::if_(Boolean<true>{}, NonCopyable<3>{}, NonCopyable<4>{}).value == 3, "");
51 static_assert(hana::if_(Boolean<false>{}, NonCopyable<3>{}, NonCopyable<4>{}).value == 4, "");
52
main()53 int main() { }
54