prev.hpp

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//
// Created by cosge on 2023-12-25.
//
 
#ifndef VCCC_ITERATOR_PREV_HPP_
#define VCCC_ITERATOR_PREV_HPP_
 
#include <type_traits>
 
#include "vccc/__core/inline_or_static.hpp"
#include "vccc/__iterator/bidirectional_iterator.hpp"
#include "vccc/__iterator/iter_difference_t.hpp"
#include "vccc/__iterator/advance.hpp"
 
namespace vccc {
namespace ranges {
namespace detail {
 
struct prev_niebloid {
  template<typename I>
  constexpr std::enable_if_t<bidirectional_iterator<I>::value, I>
  operator()(I i) const {
    --i;
    return i;
  }
 
  template<typename I>
  constexpr std::enable_if_t<bidirectional_iterator<I>::value, I>
  operator()(I i, iter_difference_t<I> n) const {
    ranges::advance(i, -n);
    return i;
  }
 
 
  template<typename I>
  constexpr std::enable_if_t<bidirectional_iterator<I>::value, I>
  operator()(I i, iter_difference_t<I> n, I bound) const {
    ranges::advance(i, -n, bound);
    return i;
  }
};
 
} // namespace detail
 
namespace niebloid {
 
 
VCCC_INLINE_OR_STATIC constexpr detail::prev_niebloid prev{};
 
 
} // namespace niebloid
using namespace niebloid;
 
} // namespace ranges
} // namespace vccc
 
#endif // VCCC_ITERATOR_PREV_HPP_