- using ::double_conversion::DoubleToStringConverter;
- using ::double_conversion::StringBuilder;
-
- arg.validate(FormatArg::Type::FLOAT);
-
- if (arg.presentation == FormatArg::kDefaultPresentation) {
- arg.presentation = 'g';
- }
-
- const char* infinitySymbol = isupper(arg.presentation) ? "INF" : "inf";
- const char* nanSymbol = isupper(arg.presentation) ? "NAN" : "nan";
- char exponentSymbol = isupper(arg.presentation) ? 'E' : 'e';
-
- if (arg.precision == FormatArg::kDefaultPrecision) {
- arg.precision = 6;
- }
-
- // 2+: for null terminator and optional sign shenanigans.
- char buf[2 + std::max({
- (2 + DoubleToStringConverter::kMaxFixedDigitsBeforePoint +
- DoubleToStringConverter::kMaxFixedDigitsAfterPoint),
- (8 + DoubleToStringConverter::kMaxExponentialDigits),
- (7 + DoubleToStringConverter::kMaxPrecisionDigits)})];
- StringBuilder builder(buf + 1, static_cast<int> (sizeof(buf) - 1));
-
- char plusSign;
- switch (arg.sign) {
- case FormatArg::Sign::PLUS_OR_MINUS:
- plusSign = '+';
- break;
- case FormatArg::Sign::SPACE_OR_MINUS:
- plusSign = ' ';
- break;
- default:
- plusSign = '\0';
- break;
- };
-
- auto flags =
- DoubleToStringConverter::EMIT_POSITIVE_EXPONENT_SIGN |
- (arg.trailingDot ? DoubleToStringConverter::EMIT_TRAILING_DECIMAL_POINT
- : 0);
-
- double val = val_;
- switch (arg.presentation) {
- case '%':
- val *= 100;
- case 'f':
- case 'F':
- {
- if (arg.precision >
- DoubleToStringConverter::kMaxFixedDigitsAfterPoint) {
- arg.precision = DoubleToStringConverter::kMaxFixedDigitsAfterPoint;
- }
- DoubleToStringConverter conv(flags,
- infinitySymbol,
- nanSymbol,
- exponentSymbol,
- -4,
- arg.precision,
- 0,
- 0);
- arg.enforce(conv.ToFixed(val, arg.precision, &builder),
- "fixed double conversion failed");
- }
- break;
- case 'e':
- case 'E':
- {
- if (arg.precision > DoubleToStringConverter::kMaxExponentialDigits) {
- arg.precision = DoubleToStringConverter::kMaxExponentialDigits;
- }
-
- DoubleToStringConverter conv(flags,
- infinitySymbol,
- nanSymbol,
- exponentSymbol,
- -4,
- arg.precision,
- 0,
- 0);
- arg.enforce(conv.ToExponential(val, arg.precision, &builder));
- }
- break;
- case 'n': // should be locale-aware, but isn't
- case 'g':
- case 'G':
- {
- if (arg.precision < DoubleToStringConverter::kMinPrecisionDigits) {
- arg.precision = DoubleToStringConverter::kMinPrecisionDigits;
- } else if (arg.precision >
- DoubleToStringConverter::kMaxPrecisionDigits) {
- arg.precision = DoubleToStringConverter::kMaxPrecisionDigits;
- }
- DoubleToStringConverter conv(flags,
- infinitySymbol,
- nanSymbol,
- exponentSymbol,
- -4,
- arg.precision,
- 0,
- 0);
- arg.enforce(conv.ToShortest(val, &builder));
- }
- break;
- default:
- arg.error("invalid specifier '", arg.presentation, "'");
- }
-
- int len = builder.position();
- builder.Finalize();
- DCHECK_GT(len, 0);
-
- // Add '+' or ' ' sign if needed
- char* p = buf + 1;
- // anything that's neither negative nor nan
- int prefixLen = 0;
- if (plusSign && (*p != '-' && *p != 'n' && *p != 'N')) {
- *--p = plusSign;
- ++len;
- prefixLen = 1;
- } else if (*p == '-') {
- prefixLen = 1;
- }
-
- format_value::formatNumber(StringPiece(p, len), prefixLen, arg, cb);