search_n.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2019 Tobias Hienzsch
 
#ifndef TETL_ALGORITHM_SEARCH_N_HPP
#define TETL_ALGORITHM_SEARCH_N_HPP
 
#include <etl/_functional/equal_to.hpp>
 
namespace etl {
 
/// \ingroup algorithm
/// @{
 
/// \brief Searches the range `[first, last)` for the first sequence of count
/// identical elements, each equal to the given value.
template <typename ForwardIt, typename Size, typename ValueT, typename Predicate>
[[nodiscard]] constexpr auto search_n(ForwardIt first, ForwardIt last, Size count, ValueT const& value, Predicate pred)
    -> ForwardIt
{
    if (count <= Size{}) {
        return first;
    }
 
    auto localCounter = Size{};
    ForwardIt found   = nullptr;
 
    for (; first != last; ++first) {
        if (pred(*first, value)) {
            localCounter++;
            if (found == nullptr) {
                found = first;
            }
        } else {
            localCounter = 0;
        }
 
        if (localCounter == count) {
            return found;
        }
    }
 
    return last;
}
 
template <typename ForwardIt, typename Size, typename ValueT>
[[nodiscard]] constexpr auto search_n(ForwardIt first, ForwardIt last, Size count, ValueT const& value) -> ForwardIt
{
    return etl::search_n(first, last, count, value, etl::equal_to());
}
 
/// @}
 
} // namespace etl
 
#endif // TETL_ALGORITHM_SEARCH_N_HPP