Function from_utf32

example/cacheHierarchy/fkYAML/node.hpp:2048–2080

@brief Converts a UTF-32 encoded character to UTF-8 encoded bytes. @param[in] utf32 A UTF-32 encoded character. @param[out] utf8 UTF-8 encoded bytes. @param[in] encoded_size The size of UTF-encoded bytes.

/// @param[out] utf8 UTF-8 encoded bytes.
/// @param[in] encoded_size The size of UTF-encoded bytes.
inline void from_utf32(const char32_t utf32, std::array<uint8_t, 4>& utf8, uint32_t& encoded_size) {
    if (utf32 < 0x80u) {
        utf8[0] = static_cast<uint8_t>(utf32 & 0x007F);
        encoded_size = 1;
    }
    else if (utf32 <= 0x7FFu) {
        const auto utf8_chunk = static_cast<uint16_t>(0xC080u | ((utf32 & 0x07C0u) << 2) | (utf32 & 0x3Fu));
        utf8[0] = static_cast<uint8_t>(utf8_chunk >> 8);
        utf8[1] = static_cast<uint8_t>(utf8_chunk);
        encoded_size = 2;
    }
    else if (utf32 <= 0xFFFFu) {
        const auto utf8_chunk =
            static_cast<uint32_t>(0xE08080u | ((utf32 & 0xF000u) << 4) | ((utf32 & 0x0FC0u) << 2) | (utf32 & 0x3F));
        utf8[0] = static_cast<uint8_t>(utf8_chunk >> 16);
        utf8[1] = static_cast<uint8_t>(utf8_chunk >> 8);
        utf8[2] = static_cast<uint8_t>(utf8_chunk);
        encoded_size = 3;
    }
    else if (utf32 <= 0x10FFFFu) {
        const auto utf8_chunk = static_cast<uint32_t>(
            0xF0808080u | ((utf32 & 0x1C0000u) << 6) | ((utf32 & 0x03F000u) << 4) | ((utf32 & 0x0FC0u) << 2) |
            (utf32 & 0x3Fu));
        utf8[0] = static_cast<uint8_t>(utf8_chunk >> 24);
        utf8[1] = static_cast<uint8_t>(utf8_chunk >> 16);
        utf8[2] = static_cast<uint8_t>(utf8_chunk >> 8);
        utf8[3] = static_cast<uint8_t>(utf8_chunk);
        encoded_size = 4;
    }
    else {
        throw invalid_encoding("Invalid UTF-32 encoding detected.", utf32);
    }
}

} // namespace utf8