func ParseUUID()

in uuid.go [84:106]

• 23 lines of code
• 14 McCabe index (conditional complexity)

func ParseUUID(input string) (UUID, error) {
	var u UUID
	j := 0
	for _, r := range input {
		switch {
		case r == '-' && j&1 == 0:
			continue
		case r >= '0' && r <= '9' && j < 32:
			u[j/2] |= byte(r-'0') << uint(4-j&1*4)
		case r >= 'a' && r <= 'f' && j < 32:
			u[j/2] |= byte(r-'a'+10) << uint(4-j&1*4)
		case r >= 'A' && r <= 'F' && j < 32:
			u[j/2] |= byte(r-'A'+10) << uint(4-j&1*4)
		default:
			return UUID{}, fmt.Errorf("invalid UUID %q", input)
		}
		j += 1
	}
	if j != 32 {
		return UUID{}, fmt.Errorf("invalid UUID %q", input)
	}
	return u, nil
}