59 lines
1.8 KiB
C++
59 lines
1.8 KiB
C++
/*!
|
|
@file
|
|
Defines `boost::hana::min`.
|
|
|
|
@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_MIN_HPP
|
|
#define BOOST_HANA_MIN_HPP
|
|
|
|
#include <boost/hana/fwd/min.hpp>
|
|
|
|
#include <boost/hana/concept/orderable.hpp>
|
|
#include <boost/hana/config.hpp>
|
|
#include <boost/hana/core/dispatch.hpp>
|
|
#include <boost/hana/if.hpp>
|
|
#include <boost/hana/less.hpp>
|
|
|
|
|
|
BOOST_HANA_NAMESPACE_BEGIN
|
|
//! @cond
|
|
template <typename X, typename Y>
|
|
constexpr decltype(auto) min_t::operator()(X&& x, Y&& y) const {
|
|
using T = typename hana::tag_of<X>::type;
|
|
using U = typename hana::tag_of<Y>::type;
|
|
using Min = BOOST_HANA_DISPATCH_IF(decltype(min_impl<T, U>{}),
|
|
hana::Orderable<T>::value &&
|
|
hana::Orderable<U>::value
|
|
);
|
|
|
|
#ifndef BOOST_HANA_CONFIG_DISABLE_CONCEPT_CHECKS
|
|
static_assert(hana::Orderable<T>::value,
|
|
"hana::min(x, y) requires 'x' to be Orderable");
|
|
|
|
static_assert(hana::Orderable<U>::value,
|
|
"hana::min(x, y) requires 'y' to be Orderable");
|
|
#endif
|
|
|
|
return Min::apply(static_cast<X&&>(x), static_cast<Y&&>(y));
|
|
}
|
|
//! @endcond
|
|
|
|
template <typename T, typename U, bool condition>
|
|
struct min_impl<T, U, when<condition>> : default_ {
|
|
template <typename X, typename Y>
|
|
static constexpr decltype(auto) apply(X&& x, Y&& y) {
|
|
decltype(auto) cond = hana::less(x, y);
|
|
return hana::if_(static_cast<decltype(cond)&&>(cond),
|
|
static_cast<X&&>(x),
|
|
static_cast<Y&&>(y)
|
|
);
|
|
}
|
|
};
|
|
BOOST_HANA_NAMESPACE_END
|
|
|
|
#endif // !BOOST_HANA_MIN_HPP
|