reverse.hpp

Go to the documentation of this file.

//
// Created by yonggyulee on 2/3/24.
//
 
#ifndef VCCC_RANGES_VIEWS_REVERSE_HPP
#define VCCC_RANGES_VIEWS_REVERSE_HPP
 
#include <iterator>
#include <type_traits>
#include <utility>
 
#include "vccc/__core/inline_or_static.hpp"
#include "vccc/__ranges/range_adaptor_closure.hpp"
#include "vccc/__ranges/subrange.hpp"
#include "vccc/__ranges/viewable_range.hpp"
#include "vccc/__ranges/views/all.hpp"
#include "vccc/__ranges/views/reverse_view.hpp"
#include "vccc/__type_traits/detail/return_category.hpp"
#include "vccc/__type_traits/is_specialization.hpp"
#include "vccc/__type_traits/remove_cvref.hpp"
 
namespace vccc {
namespace ranges {
namespace views {
namespace detail {
 
using vccc::detail::return_category;
 
class reverse_adaptor_object : public range_adaptor_closure<reverse_adaptor_object> {
  template<typename R>
  struct is_reverse_subrange : return_category<0> {};
  template<typename I, subrange_kind K>
  struct is_reverse_subrange<subrange<std::reverse_iterator<I>, std::reverse_iterator<I>, K>>
      : return_category<2, subrange<I, I, K>> {};
 
  template<typename R>
  using reverse_tag = std::conditional_t<
        is_specialization<remove_cvref_t<R>, reverse_view>::value, return_category<1>,
        is_reverse_subrange<remove_cvref_t<R>>
      >;
 
  template<typename R>
  constexpr auto call(R&& r, return_category<1>) const {
    return std::forward<decltype(std::forward<R>(r).base())>(std::forward<R>(r).base());
  }
 
  template<typename R, typename I>
  constexpr auto call(R&& r, return_category<2, subrange<I, I, subrange_kind::sized>>) const {
    return subrange<I, I, subrange_kind::sized>(r.end().base(), r.begin().base(), r.size());
  }
 
  template<typename R, typename I>
  constexpr auto call(R&& r, return_category<2, subrange<I, I, subrange_kind::unsized>>) const {
    return subrange<I, I, subrange_kind::unsized>(r.end().base(), r.begin().base());
  }
 
  template<typename R>
  constexpr auto call(R&& r, return_category<0>) const {
    return reverse_view<all_t<R>>(std::forward<R>(r));
  }
 
 public:
  template<typename R, std::enable_if_t<viewable_range<R>::value, int> = 0>
  constexpr auto operator()(R&& r) const {
    return call(std::forward<R>(r), reverse_tag<R>{});
  }
};
 
} // namespace detail
 
 
VCCC_INLINE_OR_STATIC constexpr detail::reverse_adaptor_object reverse{};
 
 
} // namespace views
} // namespace ranges
} // namespace vccc
 
#endif // VCCC_RANGES_VIEWS_REVERSE_HPP