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refactor: 💥 unit_symbol<fmt>(U) signature refactored and the resulting text can now also be used at runtime

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Resolves (#501)
This commit is contained in:
Mateusz Pusz
2023-10-17 09:09:18 +02:00
parent 909d9a7089
commit ff3d1e87fa
1 changed files with 28 additions and 4 deletions
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32
src/core/include/mp-units/unit.h
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@@ -809,12 +809,36 @@ constexpr Out unit_symbol_to(Out out, U u, unit_symbol_formatting fmt = unit_sym
return detail::unit_symbol_impl<CharT>(out, u, fmt, false); return detail::unit_symbol_impl<CharT>(out, u, fmt, false);
} }
template<typename CharT = char, Unit U> namespace detail {
[[nodiscard]] constexpr std::basic_string<CharT> unit_symbol(U u, unit_symbol_formatting fmt = unit_symbol_formatting{})
template<typename CharT, std::size_t N, unit_symbol_formatting fmt, Unit U>
[[nodiscard]] consteval std::array<CharT, N + 1> get_symbol_buffer(U)
{ {
std::basic_string<CharT> buffer; std::array<CharT, N + 1> buffer{};
unit_symbol_to<CharT>(std::back_inserter(buffer), u, fmt); unit_symbol_to<CharT>(buffer.begin(), U{}, fmt);
return buffer; return buffer;
} }
} // namespace detail
template<unit_symbol_formatting fmt = unit_symbol_formatting{}, typename CharT = char, Unit U>
[[nodiscard]] constexpr auto unit_symbol(U)
{
auto get_size = []() consteval {
std::basic_string<CharT> buffer;
unit_symbol_to<CharT>(std::back_inserter(buffer), U{}, fmt);
return buffer.size();
};
#if __cpp_constexpr >= 202211L // Permitting static constexpr variables in constexpr functions
static constexpr std::size_t size = get_size();
static constexpr auto buffer = detail::get_symbol_buffer<CharT, size, fmt>(U{});
return std::string_view(buffer.data(), size);
#else
constexpr std::size_t size = get_size();
constexpr auto buffer = detail::get_symbol_buffer<CharT, size, fmt>(U{});
return basic_fixed_string(buffer.data(), std::integral_constant<std::size_t, size>{});
#endif
}
} // namespace mp_units } // namespace mp_units