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Sprout/sprout/functional/bind1st.hpp
2015-01-10 19:13:57 +09:00

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2.7 KiB
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/*=============================================================================
Copyright (c) 2011-2015 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_BIND1ST_HPP
#define SPROUT_FUNCTIONAL_BIND1ST_HPP
#include <type_traits>
#include <utility>
#include <sprout/config.hpp>
#include <sprout/functional/base.hpp>
#include <sprout/functional/type_traits/is_strict_function.hpp>
namespace sprout {
// D.9.1 Class template binder1st
namespace detail {
template<typename Fn, typename T = void, typename = void>
class binder1st;
template<typename Fn, typename T>
class binder1st<
Fn, T,
typename std::enable_if<sprout::is_strict_binary_function<Fn>::value>::type
>
: public sprout::unary_function<typename Fn::second_argument_type, typename Fn::result_type>
{
public:
typedef typename std::conditional<
std::is_void<T>::value,
typename Fn::first_argument_type,
T
>::type value_type;
protected:
Fn op;
value_type value;
public:
SPROUT_CONSTEXPR binder1st(Fn const& x, value_type const& y)
: op(x), value(y)
{}
SPROUT_CONSTEXPR typename Fn::result_type
operator()(typename Fn::second_argument_type const& x) const {
return op(value, x);
}
};
template<typename Fn, typename T>
class binder1st<
Fn, T,
typename std::enable_if<!sprout::is_strict_binary_function<Fn>::value>::type
> {
public:
typedef T value_type;
protected:
Fn op;
value_type value;
public:
SPROUT_CONSTEXPR binder1st(Fn const& x, value_type const& y)
: op(x), value(y)
{}
template<typename U>
SPROUT_CONSTEXPR decltype(std::declval<Fn const&>()(std::declval<value_type const&>(), std::declval<U const&>()))
operator()(U const& x) const {
return op(value, x);
}
};
} // namespace detail
template<typename Fn, typename T = void>
class binder1st
: public sprout::detail::binder1st<Fn, T>
{
public:
typedef typename sprout::detail::binder1st<Fn, T>::value_type value_type;
public:
SPROUT_CONSTEXPR binder1st(Fn const& x, value_type const& y)
: sprout::detail::binder1st<Fn, T>(x, y)
{}
};
// D.9.2 bind1st
template<typename Fn, typename T>
inline SPROUT_CONSTEXPR sprout::binder1st<Fn, T>
bind1st(Fn const& fn, T const& x) {
return sprout::binder1st<Fn, T>(fn, typename sprout::binder1st<Fn, T>::value_type(x));
}
} // namespace sprout
#endif // #ifndef SPROUT_FUNCTIONAL_BIND1ST_HPP