blob: 65df2bf3c4625c6d640c28c0e31a093a04400456 (
plain)
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
Forward declares `boost::hana::one`.
@copyright Louis Dionne 2013-2016
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_FWD_ONE_HPP
#define BOOST_HANA_FWD_ONE_HPP
#include <boost/hana/config.hpp>
#include <boost/hana/core/when.hpp>
BOOST_HANA_NAMESPACE_BEGIN
//! Identity of the `Ring` multiplication.
//! @ingroup group-Ring
//!
//! @tparam R
//! The tag (must be a model of `Ring`) of the returned identity.
//!
//!
//! Example
//! -------
//! @include example/one.cpp
#ifdef BOOST_HANA_DOXYGEN_INVOKED
template <typename R>
constexpr auto one = []() -> decltype(auto) {
return tag-dispatched;
};
#else
template <typename R, typename = void>
struct one_impl : one_impl<R, when<true>> { };
template <typename R>
struct one_t;
template <typename R>
constexpr one_t<R> one{};
#endif
BOOST_HANA_NAMESPACE_END
#endif // !BOOST_HANA_FWD_ONE_HPP
|
