max_element.hpp

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//
// Created by YongGyu Lee on 01/08/24.
//
 
#ifndef VCCC_ALGORITHM_RANGES_MAX_ELEMENT_HPP
#define VCCC_ALGORITHM_RANGES_MAX_ELEMENT_HPP
 
#include <functional>
#include <type_traits>
 
#include "vccc/__algorithm/ranges/detail/check_input.hpp"
#include "vccc/__core/inline_or_static.hpp"
#include "vccc/__functional/identity.hpp"
#include "vccc/__functional/invoke.hpp"
#include "vccc/__functional/less.hpp"
#include "vccc/__iterator/forward_iterator.hpp"
#include "vccc/__iterator/indirect_strict_weak_order.hpp"
#include "vccc/__iterator/projected.hpp"
#include "vccc/__iterator/sentinel_for.hpp"
#include "vccc/__ranges/begin.hpp"
#include "vccc/__ranges/borrowed_iterator_t.hpp"
#include "vccc/__ranges/end.hpp"
#include "vccc/__ranges/forward_range.hpp"
#include "vccc/__ranges/iterator_t.hpp"
#include "vccc/__type_traits/conjunction.hpp"
 
namespace vccc {
namespace ranges {
namespace detail {
 
struct max_element_niebloid {
  template<typename I, typename S, typename Proj = identity, typename Comp = ranges::less, std::enable_if_t<
      algo_check_unary_forward_iterator<indirect_strict_weak_order, I, S, Proj, Comp>
  ::value, int> = 0>
  constexpr I operator()(I first, S last, Comp comp = {}, Proj proj = {}) const {
    if (first == last)
      return last;
 
    auto it = first;
    while (++first != last) {
      if (vccc::invoke(comp, vccc::invoke(proj, *it), vccc::invoke(proj, *first)))
        it = first;
    }
    return it;
  }
 
  template<typename R, typename Proj = identity, typename Comp = less, std::enable_if_t<
      algo_check_unary_forward_range<indirect_strict_weak_order, R, Proj, Comp>
  ::value, int> = 0>
  constexpr borrowed_iterator_t<R>
  operator()(R&& r, Comp comp = {}, Proj proj = {}) const {
    return (*this)(ranges::begin(r), ranges::end(r), std::ref(comp), std::ref(proj));
  }
};
 
} // namespace detail
 
 
VCCC_INLINE_OR_STATIC constexpr detail::max_element_niebloid max_element{};
 
 
} // namespace ranges
} // namespace vccc
 
#endif // VCCC_ALGORITHM_RANGES_MAX_ELEMENT_HPP