range/hash.hpp

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// -----------------------------------------------------------------------------------------------------
// Copyright (c) 2006-2023, Knut Reinert & Freie Universität Berlin
// Copyright (c) 2016-2023, Knut Reinert & MPI für molekulare Genetik
// This file may be used, modified and/or redistributed under the terms of the 3-clause BSD-License
// shipped with this file and also available at: https://github.com/seqan/seqan3/blob/master/LICENSE.md
// -----------------------------------------------------------------------------------------------------
 
#pragma once
 
#include <ranges>
 
#include <seqan3/alphabet/hash.hpp>
#include <seqan3/core/range/type_traits.hpp>
 
namespace std
{
template <std::ranges::input_range urng_t>
    requires seqan3::semialphabet<std::ranges::range_reference_t<urng_t>>
struct hash<urng_t>
{
    template <std::ranges::input_range urng2_t>
        requires seqan3::semialphabet<std::ranges::range_reference_t<urng2_t>>
    size_t operator()(urng2_t && range) const noexcept
    {
        using alphabet_t = std::ranges::range_reference_t<urng_t>;
        size_t result{0};
        hash<alphabet_t> h{};
        for (alphabet_t character : range)
        {
            result *= seqan3::alphabet_size<alphabet_t>;
            result += h(character);
        }
        return result;
    }
};
 
} // namespace std