Sprout/sprout/range/adaptor/taken.hpp
2012-12-01 03:00:46 +09:00

77 lines
2.3 KiB
C++

#ifndef SPROUT_RANGE_ADAPTOR_TAKEN_HPP
#define SPROUT_RANGE_ADAPTOR_TAKEN_HPP
#include <type_traits>
#include <sprout/config.hpp>
#include <sprout/container/traits.hpp>
#include <sprout/container/functions.hpp>
#include <sprout/iterator/next.hpp>
#include <sprout/range/adaptor/detail/adapted_range_default.hpp>
#include <sprout/type_traits/lvalue_reference.hpp>
#include <sprout/utility/lvalue_forward.hpp>
#include HDR_ALGORITHM_SSCRISK_CEL_OR_SPROUT
namespace sprout {
namespace adaptors {
//
// take_holder
//
template<typename Difference>
class take_holder {
public:
typedef Difference difference_type;
private:
difference_type distance_;
public:
explicit SPROUT_CONSTEXPR take_holder(difference_type distance)
: distance_(distance)
{}
SPROUT_CONSTEXPR difference_type const& distance() const {
return distance_;
}
};
//
// taken_forwarder
//
class taken_forwarder {
public:
template<typename Difference>
SPROUT_CONSTEXPR sprout::adaptors::take_holder<Difference>
operator()(Difference distance) {
return sprout::adaptors::take_holder<Difference>(distance);
}
};
//
// taken
//
namespace {
SPROUT_STATIC_CONSTEXPR sprout::adaptors::taken_forwarder taken{};
} // anonymous-namespace
//
// operator|
//
template<typename Range, typename Difference>
inline SPROUT_CONSTEXPR sprout::adaptors::detail::adapted_range_default<
typename std::remove_reference<typename sprout::lvalue_reference<Range>::type>::type
>
operator|(Range&& lhs, sprout::adaptors::take_holder<Difference> const& rhs) {
typedef typename sprout::container_traits<
typename std::remove_reference<typename sprout::lvalue_reference<Range>::type>::type
>::difference_type difference_type;
return sprout::adaptors::detail::adapted_range_default<
typename std::remove_reference<typename sprout::lvalue_reference<Range>::type>::type
>(
sprout::begin(sprout::lvalue_forward<Range>(lhs)),
sprout::next(
sprout::begin(sprout::lvalue_forward<Range>(lhs)),
NS_SSCRISK_CEL_OR_SPROUT::min<difference_type>(rhs.distance(), sprout::size(sprout::lvalue_forward<Range>(lhs)))
)
);
}
} // namespace adaptors
} // namespace sprout
#endif // #ifndef SPROUT_RANGE_ADAPTOR_TAKEN_HPP