hakorune/apps/tests/phase286_pattern8_plan_poc.hako

box StringUtils {
    is_digit(ch) {
        return ch == "0" or ch == "1" or ch == "2" or ch == "3" or ch == "4"
            or ch == "5" or ch == "6" or ch == "7" or ch == "8" or ch == "9"
    }

    is_integer(s) {
        if s.length() == 0 {
            return false
        }

        local start = 0
        if s.substring(0, 1) == "-" {
            if s.length() == 1 {
                return false
            }
            start = 1
        }

        local i = start
        loop(i < s.length()) {
            if not me.is_digit(s.substring(i, i + 1)) {
                return false
            }
            i = i + 1
        }
        return true
    }
}

static box Main {
    main() {
        local u
        u = new StringUtils()
        if u.is_integer("123") {
            return 7
        } else {
            return 1
        }
    }
}