Sprout/sprout/functional/less.hpp
2014-02-22 16:32:51 +09:00

46 lines
1.3 KiB
C++

/*=============================================================================
Copyright (c) 2011-2014 Bolero MURAKAMI
Copyright (C) 2011 RiSK (sscrisk)
https://github.com/bolero-MURAKAMI/Sprout
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)
=============================================================================*/
#ifndef SPROUT_FUNCTIONAL_LESS_HPP
#define SPROUT_FUNCTIONAL_LESS_HPP
#include <utility>
#include <sprout/config.hpp>
#include <sprout/utility/forward.hpp>
namespace sprout {
// 20.8.5 Comparisons
template<typename T = void>
struct less {
public:
typedef T first_argument_type;
typedef T second_argument_type;
typedef bool result_type;
public:
SPROUT_CONSTEXPR bool operator()(T const& x, T const& y) const {
return x < y;
}
};
template<>
struct less<void> {
public:
typedef void is_transparent;
public:
template<typename T, typename U>
SPROUT_CONSTEXPR decltype(std::declval<T>() < std::declval<U>())
operator()(T&& x, U&& y)
const SPROUT_NOEXCEPT_EXPR(SPROUT_NOEXCEPT_EXPR(std::declval<T>() < std::declval<U>()))
{
return SPROUT_FORWARD(T, x) < SPROUT_FORWARD(U, y);
}
};
} // namespace sprout
#endif // #ifndef SPROUT_FUNCTIONAL_LESS_HPP