Function RunFormatterFullScan

library/cpp/yt/string/format-inl.h:1047–1124

template <CFormatter TFormatter>
void RunFormatterFullScan(
    TStringBuilderBase* builder,
    TStringBuf format,
    const TFormatter& formatter,
    int argIndex = 0)
{
    auto current = std::begin(format);
    auto end = std::end(format);
    while (true) {
        // Scan verbatim part until stop symbol.
        auto verbatimBegin = current;
        auto verbatimEnd = std::find(current, end, IntroductorySymbol);

        // Copy verbatim part, if any.
        size_t verbatimSize = verbatimEnd - verbatimBegin;
        if (verbatimSize > 0) {
            builder->AppendString(TStringBuf(verbatimBegin, verbatimSize));
        }

        // Handle stop symbol.
        current = verbatimEnd;
        if (current == end) {
            break;
        }

        YT_ASSERT(*current == IntroductorySymbol);
        ++current;

        if (*current == IntroductorySymbol) {
            // Verbatim %.
            builder->AppendChar(IntroductorySymbol);
            ++current;
            continue;
        }

        // Scan format part until stop symbol.
        auto argFormatBegin = current;
        auto argFormatEnd = argFormatBegin;
        bool singleQuotes = false;
        bool doubleQuotes = false;

        static constexpr TStringBuf conversionSpecifiers =
            "diuoxXfFeEgGaAcspn";

        while (
            argFormatEnd != end &&
            *argFormatEnd != GenericSpecSymbol &&            // value in generic format
            !conversionSpecifiers.Contains(*argFormatEnd)) // others are standard specifiers supported by printf
        {
            switch (*argFormatEnd) {
                case 'q':
                    singleQuotes = true;
                    break;
                case 'Q':
                    doubleQuotes = true;
                    break;
                case 'h':
                    break;