io/detail/misc.hpp

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// SPDX-FileCopyrightText: 2006-2025 Knut Reinert & Freie Universität Berlin
// SPDX-FileCopyrightText: 2016-2025 Knut Reinert & MPI für molekulare Genetik
// SPDX-License-Identifier: BSD-3-Clause
 
#pragma once
 
#include <algorithm>
#include <filesystem>
#include <iterator>
#include <variant>
#include <vector>
 
#include <seqan3/core/detail/template_inspection.hpp>
#include <seqan3/io/exception.hpp>
#include <seqan3/utility/type_list/detail/type_list_algorithm.hpp>
 
namespace seqan3::detail
{
 
template <typename list_t, template <typename...> typename output_t>
struct variant_from_tags;
 
template <template <typename...> typename output_t, typename... ts>
struct variant_from_tags<type_list<ts...>, output_t>
{
    using type = std::variant<output_t<ts>...>;
};
 
template <std::output_iterator<char> it_t>
constexpr void write_eol(it_t & it, bool const add_cr)
{
    if (add_cr)
        it = '\r';
 
    it = '\n';
}
 
template <typename format_variant_type>
void set_format(format_variant_type & format, std::filesystem::path const & file_name)
{
    using valid_formats = detail::transfer_template_args_onto_t<format_variant_type, type_list>;
 
    bool format_found = false;
    std::string extension = file_name.extension().string();
    if (extension.size() > 1)
    {
        extension = extension.substr(1); // drop leading "."
        detail::for_each<valid_formats>(
            [&](auto fmt)
            {
                using fm_type = typename decltype(fmt)::type; // remove type_identity wrapper
 
                for (auto const & ext : fm_type::file_extensions)
                {
                    if (std::ranges::equal(ext, extension))
                    {
                        format.template emplace<fm_type>();
                        format_found = true;
                        return;
                    }
                }
            });
    }
 
    if (!format_found)
        throw unhandled_extension_error("No valid format found for this extension.");
}
 
template <typename list_t>
inline constexpr bool has_member_file_extensions = false;
 
template <template <typename...> typename list_t, typename... ts>
    requires (
                 requires { ts::file_extensions; },
                 ...,
                 true)
inline constexpr bool has_member_file_extensions<list_t<ts...>> = true;
 
template <typename query_t>
inline constexpr bool has_type_valid_formats = false;
 
template <typename query_t>
    requires requires { typename query_t::valid_formats; }
inline constexpr bool has_type_valid_formats<query_t> = true;
 
template <typename formats_t>
inline std::vector<std::string> valid_file_extensions()
{
    static_assert(has_member_file_extensions<formats_t>,
                  "Expects that all formats have a static member file_extensions storing the extensions in a range");
 
    std::vector<std::string> extensions;
    detail::for_each<formats_t>(
        [&extensions](auto t_identity)
        {
            using format_t = typename decltype(t_identity)::type;
            std::ranges::copy(format_t::file_extensions, std::back_inserter(extensions));
        });
 
    return extensions;
}
} // namespace seqan3::detail