search.hpp

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//
// Created by yonggyulee on 2/3/24.
//
 
#ifndef VCCC_ALGORITHM_SEARCH_HPP
#define VCCC_ALGORITHM_SEARCH_HPP
 
#include <type_traits>
#include <utility>
 
#include "vccc/__core/inline_or_static.hpp"
#include "vccc/__functional/equal_to.hpp"
#include "vccc/__functional/identity.hpp"
#include "vccc/__functional/invoke.hpp"
#include "vccc/__iterator/forward_iterator.hpp"
#include "vccc/__iterator/indirectly_comparable.hpp"
#include "vccc/__iterator/sentinel_for.hpp"
#include "vccc/__ranges/begin.hpp"
#include "vccc/__ranges/borrowed_subrange_t.hpp"
#include "vccc/__ranges/end.hpp"
#include "vccc/__ranges/forward_range.hpp"
#include "vccc/__ranges/iterator_t.hpp"
#include "vccc/__ranges/subrange.hpp"
#include "vccc/__type_traits/conjunction.hpp"
 
namespace vccc {
namespace ranges {
namespace detail {
 
struct search_niebloid {
 private:
  template<typename R1, typename R2, typename Pred, typename Proj1, typename Proj2,
           bool = conjunction<forward_range<R1>, forward_range<R2>>::value /* false */>
  struct check_range : std::false_type {};
  template<typename R1, typename R2, typename Pred, typename Proj1, typename Proj2>
  struct check_range<R1, R2, Pred, Proj1, Proj2, true>
      : indirectly_comparable<iterator_t<R1>, iterator_t<R2>, Pred, Proj1, Proj2> {};
 
 public:
  template<
      typename I1, typename S1,
      typename I2, typename S2,
      typename Pred = equal_to, typename Proj1 = identity, typename Proj2 = identity,
      std::enable_if_t<conjunction<
          forward_iterator<I1>, sentinel_for<S1, I1>,
          forward_iterator<I2>, sentinel_for<S2, I2>,
          indirectly_comparable<I1, I2, Pred, Proj1, Proj2>
      >::value, int> = 0
  >
  constexpr subrange<I1>
  operator()(I1 first1, S1 last1, I2 first2, S2 last2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const {
    for (;; ++first1) {
      I1 it1 = first1;
      I2 it2 = first2;
      for (;; ++it1, (void)++it2) {
        if (it2 == last2)
          return {first1, it1};
        if (it1 == last1)
          return {it1, it1};
        if (!vccc::invoke(pred, vccc::invoke(proj1, *it1), vccc::invoke(proj2, *it2)))
          break;
      }
    }
 
    // unreachable
    return {last1, last1};
  }
 
  template<
      typename R1, typename R2,
      typename Pred = equal_to, typename Proj1 = identity, typename Proj2 = identity,
      std::enable_if_t<check_range<R1, R2, Pred, Proj1, Proj2>::value, int> = 0
  >
  constexpr borrowed_subrange_t<R1>
  operator()(R1&& r1, R2&& r2, Pred pred = {}, Proj1 proj1 = {}, Proj2 proj2 = {}) const {
    return (*this)(ranges::begin(r1), ranges::end(r1),
                   ranges::begin(r2), ranges::end(r2),
                   std::move(pred), std::move(proj1), std::move(proj2));
  }
};
 
} // namespace detail
 
 
VCCC_INLINE_OR_STATIC constexpr detail::search_niebloid search{};
 
 
} // namespace ranges
} // namespace vccc
 
#endif // VCCC_ALGORITHM_SEARCH_HPP