func()

in syntax/scan.go [910:1068]

• 137 lines of code
• 52 McCabe index (conditional complexity)

func (sc *scanner) scanNumber(val *tokenValue, c rune) Token {
	// https://github.com/google/starlark-go/blob/master/doc/spec.md#lexical-elements
	//
	// Python features not supported:
	// - integer literals of >64 bits of precision
	// - 123L or 123l long suffix
	// - traditional octal: 0755
	// https://docs.python.org/2/reference/lexical_analysis.html#integer-and-long-integer-literals

	start := sc.pos
	fraction, exponent := false, false

	if c == '.' {
		// dot or start of fraction
		sc.readRune()
		c = sc.peekRune()
		if !isdigit(c) {
			sc.endToken(val)
			return DOT
		}
		fraction = true
	} else if c == '0' {
		// hex, octal, binary or float
		sc.readRune()
		c = sc.peekRune()

		if c == '.' {
			fraction = true
		} else if c == 'x' || c == 'X' {
			// hex
			sc.readRune()
			c = sc.peekRune()
			if !isxdigit(c) {
				sc.error(start, "invalid hex literal")
			}
			for isxdigit(c) {
				sc.readRune()
				c = sc.peekRune()
			}
		} else if c == 'o' || c == 'O' {
			// octal
			sc.readRune()
			c = sc.peekRune()
			if !isodigit(c) {
				sc.error(sc.pos, "invalid octal literal")
			}
			for isodigit(c) {
				sc.readRune()
				c = sc.peekRune()
			}
		} else if c == 'b' || c == 'B' {
			// binary
			sc.readRune()
			c = sc.peekRune()
			if !isbdigit(c) {
				sc.error(sc.pos, "invalid binary literal")
			}
			for isbdigit(c) {
				sc.readRune()
				c = sc.peekRune()
			}
		} else {
			// float (or obsolete octal "0755")
			allzeros, octal := true, true
			for isdigit(c) {
				if c != '0' {
					allzeros = false
				}
				if c > '7' {
					octal = false
				}
				sc.readRune()
				c = sc.peekRune()
			}
			if c == '.' {
				fraction = true
			} else if c == 'e' || c == 'E' {
				exponent = true
			} else if octal && !allzeros {
				sc.endToken(val)
				sc.errorf(sc.pos, "obsolete form of octal literal; use 0o%s", val.raw[1:])
			}
		}
	} else {
		// decimal
		for isdigit(c) {
			sc.readRune()
			c = sc.peekRune()
		}

		if c == '.' {
			fraction = true
		} else if c == 'e' || c == 'E' {
			exponent = true
		}
	}

	if fraction {
		sc.readRune() // consume '.'
		c = sc.peekRune()
		for isdigit(c) {
			sc.readRune()
			c = sc.peekRune()
		}

		if c == 'e' || c == 'E' {
			exponent = true
		}
	}

	if exponent {
		sc.readRune() // consume [eE]
		c = sc.peekRune()
		if c == '+' || c == '-' {
			sc.readRune()
			c = sc.peekRune()
			if !isdigit(c) {
				sc.error(sc.pos, "invalid float literal")
			}
		}
		for isdigit(c) {
			sc.readRune()
			c = sc.peekRune()
		}
	}

	sc.endToken(val)
	if fraction || exponent {
		var err error
		val.float, err = strconv.ParseFloat(val.raw, 64)
		if err != nil {
			sc.error(sc.pos, "invalid float literal")
		}
		return FLOAT
	} else {
		var err error
		s := val.raw
		val.bigInt = nil
		if len(s) > 2 && s[0] == '0' && (s[1] == 'o' || s[1] == 'O') {
			val.int, err = strconv.ParseInt(s[2:], 8, 64)
		} else if len(s) > 2 && s[0] == '0' && (s[1] == 'b' || s[1] == 'B') {
			val.int, err = strconv.ParseInt(s[2:], 2, 64)
		} else {
			val.int, err = strconv.ParseInt(s, 0, 64)
			if err != nil {
				num := new(big.Int)
				var ok bool
				val.bigInt, ok = num.SetString(s, 0)
				if ok {
					err = nil
				}
			}
		}
		if err != nil {
			sc.error(start, "invalid int literal")
		}
		return INT
	}
}