to_chars.hpp

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// SPDX-License-Identifier: BSL-1.0
 
#ifndef TETL_CHARCONV_TO_CHARS_HPP
#define TETL_CHARCONV_TO_CHARS_HPP
 
#include <etl/_concepts/integral.hpp>
#include <etl/_concepts/same_as.hpp>
#include <etl/_cstddef/size_t.hpp>
#include <etl/_iterator/distance.hpp>
#include <etl/_strings/from_integer.hpp>
#include <etl/_system_error/errc.hpp>
 
namespace etl {

struct to_chars_result {
    char const* ptr{nullptr};
    etl::errc ec{};
 
    [[nodiscard]] constexpr explicit operator bool() const noexcept { return ec == etl::errc{}; }
 
    friend auto operator==(to_chars_result const&, to_chars_result const&) -> bool = default;
};

template <integral T>
    requires(not same_as<T, bool>)
[[nodiscard]] constexpr auto to_chars(char* first, char* last, T val, int base = 10) -> to_chars_result
{
    constexpr auto options = strings::from_integer_options{.terminate_with_null = false};
 
    auto const len = static_cast<etl::size_t>(etl::distance(first, last));
    auto const res = strings::from_integer<T, options>(val, first, len, base);
    if (res.error == strings::from_integer_error::none) {
        return to_chars_result{res.end, {}};
    }
    return to_chars_result{
        .ptr = last,
        .ec  = errc::value_too_large,
    };
}
 
[[nodiscard]] constexpr auto to_chars(char*, char*, bool, int = 10) -> to_chars_result = delete;
 
} // namespace etl
 
#endif // TETL_CHARCONV_TO_CHARS_HPP