Sprout/sprout/range/adaptor/adapted_dropped.hpp

72 lines
2.3 KiB
C++

#ifndef SPROUT_RANGE_ADAPTOR_ADAPTED_DROPPED_HPP
#define SPROUT_RANGE_ADAPTOR_ADAPTED_DROPPED_HPP
#include <sprout/config.hpp>
#include <sprout/utility/lvalue_forward.hpp>
#include <sprout/range/adaptor/taken.hpp>
#include <sprout/range/adaptor/dropped.hpp>
#include <sprout/range/adaptor/jointed.hpp>
namespace sprout {
namespace adaptors {
//
// adapt_drop_holder
//
template<typename Adaptor, typename Difference>
class adapt_drop_holder {
public:
typedef Adaptor adaptor_type;
typedef Difference difference_type;
private:
adaptor_type adaptor_;
difference_type distance_;
public:
explicit SPROUT_CONSTEXPR adapt_drop_holder(adaptor_type const& adaptor, difference_type distance)
: adaptor_(adaptor), distance_(distance)
{}
SPROUT_CONSTEXPR adaptor_type const& adaptor() const {
return adaptor_;
}
SPROUT_CONSTEXPR difference_type const& distance() const {
return distance_;
}
};
//
// adapted_dropped_forwarder
//
class adapted_dropped_forwarder {
public:
template<typename Adaptor, typename Difference>
SPROUT_CONSTEXPR sprout::adaptors::adapt_drop_holder<Adaptor, Difference>
operator()(Adaptor const& adaptor, Difference distance) {
return sprout::adaptors::adapt_drop_holder<Adaptor, Difference>(adaptor, distance);
}
};
//
// adapted_dropped
//
namespace {
SPROUT_STATIC_CONSTEXPR sprout::adaptors::adapted_dropped_forwarder adapted_dropped{};
} // anonymous-namespace
//
// operator|
//
template<typename Range, typename Adaptor, typename Difference>
inline SPROUT_CONSTEXPR auto
operator|(Range&& lhs, sprout::adaptors::adapt_drop_holder<Adaptor, Difference> const& rhs)
-> decltype(
sprout::lvalue_forward<Range>(lhs) | sprout::adaptors::taken(rhs.distance())
| sprout::adaptors::jointed(sprout::lvalue_forward<Range>(lhs) | sprout::adaptors::dropped(rhs.distance()) | rhs.adaptor())
)
{
return sprout::lvalue_forward<Range>(lhs) | sprout::adaptors::taken(rhs.distance())
| sprout::adaptors::jointed(sprout::lvalue_forward<Range>(lhs) | sprout::adaptors::dropped(rhs.distance()) | rhs.adaptor())
;
}
} // namespace adaptors
} // namespace sprout
#endif // #ifndef SPROUT_RANGE_ADAPTOR_ADAPTED_DROPPED_HPP