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Sprout/sprout/container/front.hpp
2016-04-17 16:11:43 +09:00

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2.7 KiB
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/*=============================================================================
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_CONTAINER_FRONT_HPP
#define SPROUT_CONTAINER_FRONT_HPP
#include <sprout/config.hpp>
#include <sprout/workaround/std/cstddef.hpp>
#include <sprout/container/traits_fwd.hpp>
#include <sprout/container/container_traits.hpp>
namespace sprout {
//
// front
//
// effect:
// sprout::container_range_traits<Container>::range_front(cont)
// [default]
// ADL callable range_front(cont) -> range_front(cont)
// [default]
// Container is T[N] -> cont[0]
// otherwise, Container is not const
// && sprout::is_const_cast_convertible<const_reference, reference>
// && (callable sprout::as_const(cont).front()
// || callable sprout::as_const(cont).begin()
// || ADL(without sprout) callable begin(sprout::as_const(cont))
// )
// -> const_cast<reference>(sprout::front(sprout::as_const(cont)))
// otherwise, callable cont.front() -> cont.front()
// otherwise -> *sprout::begin(cont)
//
template<typename Container>
inline SPROUT_CONSTEXPR typename sprout::container_traits<Container>::reference
front(Container& cont) {
return sprout::container_range_traits<Container>::range_front(cont);
}
template<typename Container>
inline SPROUT_CONSTEXPR typename sprout::container_traits<Container const>::reference
front(Container const& cont) {
return sprout::container_range_traits<Container const>::range_front(cont);
}
template<typename T, std::size_t N>
inline SPROUT_CONSTEXPR typename sprout::container_traits<T[N]>::reference
front(T (& arr)[N]) {
return sprout::container_range_traits<T[N]>::range_front(arr);
}
template<typename T, std::size_t N>
inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::reference
front(T const (& arr)[N]) {
return sprout::container_range_traits<T const[N]>::range_front(arr);
}
//
// cfront
//
template<typename Container>
inline SPROUT_CONSTEXPR typename sprout::container_traits<Container const>::reference
cfront(Container const& cont) {
return sprout::front(cont);
}
template<typename T, std::size_t N>
inline SPROUT_CONSTEXPR typename sprout::container_traits<T const[N]>::reference
cfront(T const (& arr)[N]) {
return sprout::front(arr);
}
} // namespace sprout
#include <sprout/container/container_range_traits.hpp>
#endif // #ifndef SPROUT_CONTAINER_FRONT_HPP