transform.hpp

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// -----------------------------------------------------------------------------------------------------
// Copyright (c) 2006-2022, Knut Reinert & Freie Universität Berlin
// Copyright (c) 2016-2022, 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 <array>
 
#include <seqan3/utility/concept.hpp>
#include <seqan3/utility/detail/integer_traits.hpp>
 
namespace seqan3::detail
{
 
// clang-format off
template <typename char_type>
inline constexpr std::array<char_type, detail::size_in_values_v<char_type>> to_lower_table
{
    []() constexpr
    {
        std::array<char_type, detail::size_in_values_v<char_type>> ret{};
 
        for (size_t i = 0; i < detail::size_in_values_v<char_type>; ++i)
            ret[i] = i;
 
        for (size_t i = char_type{'A'}; i <= char_type{'Z'}; ++i)
            ret[i] = ret[i] - char_type{'A'} + char_type{'a'};
 
        return ret;
    }()
};
 
template <typename char_type>
inline constexpr std::array<char_type, detail::size_in_values_v<char_type>> to_upper_table
{
    []() constexpr
    {
        std::array<char_type, detail::size_in_values_v<char_type>> ret{};
 
        for (size_t i = 0; i < detail::size_in_values_v<char_type>; ++i)
            ret[i] = i;
 
        for (size_t i = char_type{'a'}; i <= char_type{'z'}; ++i)
            ret[i] = ret[i] - char_type{'a'} + char_type{'A'};
 
        return ret;
    }()
};
// clang-format on
 
} // namespace seqan3::detail
 
namespace seqan3
{
 
template <builtin_character char_type>
constexpr char_type to_lower(char_type const c) noexcept
{
    using u_t = std::make_unsigned_t<char_type>;
    return detail::to_lower_table<char_type>[static_cast<u_t>(c)];
}
 
template <builtin_character char_type>
constexpr char_type to_upper(char_type const c) noexcept
{
    using u_t = std::make_unsigned_t<char_type>;
    return detail::to_upper_table<char_type>[static_cast<u_t>(c)];
}
 
} // namespace seqan3