printf.peg

PrintfFormat
  = tokens:PrintfFormatToken* {
      return tokens;
  }

PrintfFormatToken
  = PrintfFormatSpecifier / PrintfFormatLiteral

PrintfFormatSpecifier
  = "%"
  flags: [-+ #0]*
  width: FormatInteger?
  prec:("." FormatInteger?)?
  length:FormatLengthModifier
  value:PrintfConversionSpecifier
  {
      const precision = prec ? (prec[1] ?? '.') : null;
      return {typ: "%", flags, width, precision, length, value};
  }

FormatInteger
  = "*" / FormatDecimalInteger

FormatDecimalInteger
  = ("0" / [1-9][0-9]*) {
    return Number(text());
  }

FormatLengthModifier
  = "hh" / "h" / "ll" / "l" / "j" / "z" / "t" / "L" / ""

PrintfFormatLiteral
  = [^\"%]+ {
      return {
          typ: "literal",
          value: text()
      };
  }

PrintfConversionSpecifier
  = [%csdioxXufFeEaAgGnp]