require_concept_member.cpp
1.14 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
//
// cpp03/require_concept_member.cpp
// ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
//
// Copyright (c) 2003-2020 Christopher M. Kohlhoff (chris at kohlhoff dot com)
//
// Distributed under the Boost Software License, Version 1.0. (See accompanying
// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
//
#include "asio/require_concept.hpp"
#include <cassert>
template <int>
struct prop
{
static const bool is_requirable_concept = true;
};
template <int>
struct object
{
template <int N>
object<N> require_concept(prop<N>) const
{
return object<N>();
}
};
namespace asio {
template<int N, int M>
struct is_applicable_property<object<N>, prop<M> >
{
static const bool value = true;
};
namespace traits {
template<int N, int M>
struct require_concept_member<object<N>, prop<M> >
{
static const bool is_valid = true;
static const bool is_noexcept = true;
typedef object<M> result_type;
};
} // namespace traits
} // namespace asio
int main()
{
object<1> o1 = {};
object<2> o2 = asio::require_concept(o1, prop<2>());
(void)o2;
const object<1> o3 = {};
object<2> o4 = asio::require_concept(o3, prop<2>());
(void)o4;
}