Method readNumber

scanner.go:235–300

()

}

func (s *scanner) readNumber() token {
	const bits64, base10 = 64, 10
	c := s.current
	s.assert(isDecimal(c))
	s.saveAndAdvance()
	if c == '0' && s.checkNext("Xx") { // hexadecimal
		prefix := s.buffer.String()
		s.assert(prefix == "0x" || prefix == "0X")
		s.buffer.Reset()
		var exponent int
		fraction, c, i := s.readHexNumber(0)
		if c == '.' {
			s.advance()
			fraction, c, exponent = s.readHexNumber(fraction)
		}
		if i == 0 && exponent == 0 {
			s.numberError()
		}
		exponent *= -4
		if c == 'p' || c == 'P' {
			s.advance()
			var negativeExponent bool
			if c = s.current; c == '+' || c == '-' {
				negativeExponent = c == '-'
				s.advance()
			}
			if !isDecimal(s.current) {
				s.numberError()
			}
			_ = s.readDigits()
			if e, err := strconv.ParseInt(s.buffer.String(), base10, bits64); err != nil {
				s.numberError()
			} else if negativeExponent {
				exponent += int(-e)
			} else {
				exponent += int(e)
			}
			s.buffer.Reset()
		}
		return token{t: tkNumber, n: math.Ldexp(fraction, exponent)}
	}
	c = s.readDigits()
	if c == '.' {
		s.saveAndAdvance()
		c = s.readDigits()
	}
	if c == 'e' || c == 'E' {
		s.saveAndAdvance()
		if c = s.current; c == '+' || c == '-' {
			s.saveAndAdvance()
		}
		_ = s.readDigits()
	}
	str := s.buffer.String()
	if strings.HasPrefix(str, "0") {
		if str = strings.TrimLeft(str, "0"); str == "" || !isDecimal(rune(str[0])) {
			str = "0" + str
		}