unique.hpp

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// SPDX-License-Identifier: BSL-1.0
// SPDX-FileCopyrightText: Copyright (C) 2020 Tobias Hienzsch
 
#ifndef TETL_ALGORITHM_UNIQUE_HPP
#define TETL_ALGORITHM_UNIQUE_HPP
 
#include <etl/_functional/equal_to.hpp>
#include <etl/_utility/move.hpp>
 
namespace etl {
 
/// \ingroup algorithm
/// @{
 
/// Eliminates all except the first element from every consecutive group
/// of equivalent elements from the range `[first, last)` and returns a
/// past-the-end iterator for the new logical end of the range.
template <typename ForwardIt, typename Predicate>
constexpr auto unique(ForwardIt first, ForwardIt last, Predicate pred) -> ForwardIt
{
    if (first == last) {
        return last;
    }
 
    auto result = first;
    while (++first != last) {
        if (not pred(*result, *first) and ++result != first) {
            *result = etl::move(*first);
        }
    }
    return ++result;
}
 
template <typename ForwardIt>
constexpr auto unique(ForwardIt first, ForwardIt last) -> ForwardIt
{
    return etl::unique(first, last, etl::equal_to());
}
 
/// @}
 
} // namespace etl
 
#endif // TETL_ALGORITHM_UNIQUE_HPP