598bfd3f
 Hu Chunming
提交_GLIBCXX_USE_CX...
|
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
|
/*!
@file
Defines `boost::hana::second`.
Copyright Louis Dionne 2013-2022
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_SECOND_HPP
#define BOOST_HANA_SECOND_HPP
#include <boost/hana/fwd/second.hpp>
#include <boost/hana/concept/product.hpp>
#include <boost/hana/config.hpp>
#include <boost/hana/core/dispatch.hpp>
namespace boost { namespace hana {
//! @cond
template <typename Pair>
constexpr decltype(auto) second_t::operator()(Pair&& pair) const {
using P = typename hana::tag_of<Pair>::type;
using Second = BOOST_HANA_DISPATCH_IF(second_impl<P>,
hana::Product<P>::value
);
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
static_assert(hana::Product<P>::value,
"hana::second(pair) requires 'pair' to be a Product");
#endif
return Second::apply(static_cast<Pair&&>(pair));
}
//! @endcond
template <typename P, bool condition>
struct second_impl<P, when<condition>> : default_ {
template <typename ...Args>
static constexpr auto apply(Args&& ...) = delete;
};
}} // end namespace boost::hana
#endif // !BOOST_HANA_SECOND_HPP
|
