func parseInt()

in starlark/library.go [586:653]

• 53 lines of code
• 22 McCabe index (conditional complexity)

func parseInt(s string, base int) Value {
	// remove sign
	var neg bool
	if s != "" {
		if s[0] == '+' {
			s = s[1:]
		} else if s[0] == '-' {
			neg = true
			s = s[1:]
		}
	}

	// remove optional base prefix
	baseprefix := 0
	if len(s) > 1 && s[0] == '0' {
		if len(s) > 2 {
			switch s[1] {
			case 'o', 'O':
				baseprefix = 8
			case 'x', 'X':
				baseprefix = 16
			case 'b', 'B':
				baseprefix = 2
			}
		}
		if baseprefix != 0 {
			// Remove the base prefix if it matches
			// the explicit base, or if base=0.
			if base == 0 || baseprefix == base {
				base = baseprefix
				s = s[2:]
			}
		} else {
			// For automatic base detection,
			// a string starting with zero
			// must be all zeros.
			// Thus we reject int("0755", 0).
			if base == 0 {
				for i := 1; i < len(s); i++ {
					if s[i] != '0' {
						return nil
					}
				}
				return zero
			}
		}
	}
	if base == 0 {
		base = 10
	}

	// we explicitly handled sign above.
	// if a sign remains, it is invalid.
	if s != "" && (s[0] == '-' || s[0] == '+') {
		return nil
	}

	// s has no sign or base prefix.
	if i, ok := new(big.Int).SetString(s, base); ok {
		res := MakeBigInt(i)
		if neg {
			res = zero.Sub(res)
		}
		return res
	}

	return nil
}