adjacent_find.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2020 Tobias Hienzsch
 
#ifndef TETL_ALGORITHM_ADJACENT_FIND_HPP
#define TETL_ALGORITHM_ADJACENT_FIND_HPP
 
#include <etl/_functional/equal_to.hpp>
 
namespace etl {
/// \ingroup algorithm
/// @{
 
/// \brief Searches the range `[first, last)` for two consecutive equal
/// elements. Elements are compared using the given binary predicate p.
///
/// \param first The range of elements to examine.
/// \param last The range of elements to examine.
/// \param pred Binary predicate which returns ​true if the elements should be
/// treated as equal.
///
/// https://en.cppreference.com/w/cpp/algorithm/adjacent_find
template <typename ForwardIt, typename Predicate>
[[nodiscard]] constexpr auto adjacent_find(ForwardIt first, ForwardIt last, Predicate pred) -> ForwardIt
{
    if (first == last) {
        return last;
    }
 
    auto next = first;
    ++next;
 
    for (; next != last; ++next, (void)++first) {
        if (pred(*first, *next)) {
            return first;
        }
    }
 
    return last;
}
 
template <typename ForwardIt>
[[nodiscard]] constexpr auto adjacent_find(ForwardIt first, ForwardIt last) -> ForwardIt
{
    return etl::adjacent_find(first, last, etl::equal_to());
}
 
/// @}
 
} // namespace etl
 
#endif // TETL_ALGORITHM_ADJACENT_FIND_HPP