Sprout/sprout/functional/equiv.hpp

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/*=============================================================================
2016-02-25 09:48:28 +00:00
Copyright (c) 2011-2016 Bolero MURAKAMI
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_EQUIV_HPP
#define SPROUT_FUNCTIONAL_EQUIV_HPP
#include <functional>
#include <utility>
#include <sprout/config.hpp>
#include <sprout/functional/type_traits/is_strict_function.hpp>
#include <sprout/functional/less.hpp>
#include <sprout/utility/forward.hpp>
namespace sprout {
namespace detail {
template<typename Compare, bool IsStrict = sprout::is_strict_binary_function<Compare>::value>
class equiv_adaptor_impl;
template<typename Compare>
class equiv_adaptor_impl<Compare, true> {
public:
typedef typename Compare::first_argument_type first_argument_type;
typedef typename Compare::second_argument_type second_argument_type;
typedef bool result_type;
protected:
Compare fn;
public:
explicit SPROUT_CONSTEXPR equiv_adaptor_impl(Compare const& comp)
: fn(comp)
{}
SPROUT_CONSTEXPR bool operator()(typename Compare::first_argument_type const& x, typename Compare::second_argument_type const& y) const {
return !fn(x, y) && !fn(y, x);
}
};
template<typename Compare>
class equiv_adaptor_impl<Compare, false> {
protected:
Compare fn;
public:
explicit SPROUT_CONSTEXPR equiv_adaptor_impl(Compare const& comp)
: fn(comp)
{}
template<typename T, typename U>
SPROUT_CONSTEXPR decltype(!std::declval<Compare const&>()(std::declval<T>(), std::declval<U>()) && !std::declval<Compare const&>()(std::declval<U>(), std::declval<T>()))
operator()(T&& x, U&& y) const {
return !fn(SPROUT_FORWARD(T, x), SPROUT_FORWARD(U, y)) && !fn(SPROUT_FORWARD(U, y), SPROUT_FORWARD(T, x));
}
};
} // namespace detail
//
// equiv_adaptor
//
template<typename Compare = void>
class equiv_adaptor
: public sprout::detail::equiv_adaptor_impl<Compare>
{
public:
explicit SPROUT_CONSTEXPR equiv_adaptor(Compare const& comp)
: sprout::detail::equiv_adaptor_impl<Compare>(comp)
{}
};
template<>
class equiv_adaptor<void>
: public sprout::detail::equiv_adaptor_impl<sprout::less<> >
{
public:
SPROUT_CONSTEXPR equiv_adaptor()
: sprout::detail::equiv_adaptor_impl<sprout::less<> >(sprout::less<>())
{}
explicit SPROUT_CONSTEXPR equiv_adaptor(sprout::less<> const& comp)
: sprout::detail::equiv_adaptor_impl<sprout::less<> >(comp)
{}
};
//
// equiv
//
template<typename Compare>
inline SPROUT_CONSTEXPR sprout::equiv_adaptor<Compare>
equiv(Compare const& comp) {
return sprout::equiv_adaptor<Compare>(comp);
}
inline SPROUT_CONSTEXPR sprout::equiv_adaptor<>
equiv() {
return sprout::equiv_adaptor<>();
}
} // namespace sprout
#endif // #ifndef SPROUT_FUNCTIONAL_EQUIV_HPP