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
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
|
/*!
@file
Adapts `std::pair` for use with Hana.
@copyright Louis Dionne 2013-2017
Distributed under the Boost Software License, Version 1.0.
(See accompanying file LICENSE.md or copy at http://boost.org/LICENSE_1_0.txt)
*/
#ifndef BOOST_HANA_EXT_STD_PAIR_HPP
#define BOOST_HANA_EXT_STD_PAIR_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/fwd/core/make.hpp>
#include <boost/hana/fwd/core/tag_of.hpp>
#include <boost/hana/fwd/first.hpp>
#include <boost/hana/fwd/second.hpp>
#include <utility>
#ifdef BOOST_HANA_DOXYGEN_INVOKED
namespace std {
//! @ingroup group-ext-std
//! Adaptation of `std::pair` for Hana.
//!
//!
//! Modeled concepts
//! ----------------
//! A `std::pair` models exactly the same concepts as a `hana::pair`.
//! Please refer to the documentation of `hana::pair` for details.
//!
//! @include example/ext/std/pair.cpp
template <typename First, typename Second>
struct pair { };
}
#endif
BOOST_HANA_NAMESPACE_BEGIN
namespace ext { namespace std { struct pair_tag; }}
template <typename First, typename Second>
struct tag_of<std::pair<First, Second>> {
using type = ext::std::pair_tag;
};
//////////////////////////////////////////////////////////////////////////
// Product
//////////////////////////////////////////////////////////////////////////
template <>
struct make_impl<ext::std::pair_tag> {
template <typename X, typename Y>
static constexpr decltype(auto) apply(X&& x, Y&& y) {
return std::make_pair(static_cast<X&&>(x),
static_cast<Y&&>(y));
}
};
template <>
struct first_impl<ext::std::pair_tag> {
template <typename T, typename U>
static constexpr T const& apply(std::pair<T, U> const& p)
{ return p.first; }
template <typename T, typename U>
static constexpr T& apply(std::pair<T, U>& p)
{ return p.first; }
template <typename T, typename U>
static constexpr T&& apply(std::pair<T, U>&& p)
{ return static_cast<T&&>(p.first); }
};
template <>
struct second_impl<ext::std::pair_tag> {
template <typename T, typename U>
static constexpr U const& apply(std::pair<T, U> const& p)
{ return p.second; }
template <typename T, typename U>
static constexpr U& apply(std::pair<T, U>& p)
{ return p.second; }
template <typename T, typename U>
static constexpr U&& apply(std::pair<T, U>&& p)
{ return static_cast<U&&>(p.second); }
};
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_EXT_STD_PAIR_HPP
|
