Question

I can replace ABC(10,5) with (10)%(5) using:

replaceAll("ABC\\(([^,]*)\\,([^,]*)\\)", "($1)%($2)")

but I’m unable to figure out how to do it for ABC(ABC(20,2),5) or ABC(ABC(30,2),3+2).

If I’m able to convert to ((20)%(2))%5 how can I convert back to ABC(ABC(20,2),5)?

Thanks,
j

Answer 1

I am going to answer about the first question. I was not able to do the task in a single replaceAll. I don’t think it is even achievable. However if I use loop then this should do the work for you:

    String termString = "([0-9+\\-*/()%]*)";
    String pattern = "ABC\\(" + termString + "\\," + termString + "\\)";
    String [] strings = {"ABC(10,5)", "ABC(ABC(20,2),5)", "ABC(ABC(30,2),3+2)"};
    for (String str : strings) {
        while (true) {
            String replaced = str.replaceAll(pattern, "($1)%($2)");
            if (replaced.equals(str)) {
                break;
            }
            str = replaced;
        }
        System.out.println(str);
    }

I am assuming you are writing parser for numeric expressions, thus the definition of term termString = "([0-9+\\-*/()%]*)". It outputs this:

(10)%(5)
((20)%(2))%(5)
((30)%(2))%(3+2)

EDIT As per the OP request I add the code for decoding the strings. It is a bit more hacky than the forward scenario:

    String [] encoded = {"(10)%(5)", "((20)%(2))%(5)", "((30)%(2))%(3+2)"};
    String decodeTerm = "([0-9+\\-*ABC\\[\\],]*)";
    String decodePattern = "\\(" + decodeTerm + "\\)%\\(" + decodeTerm + "\\)";
    for (String str : encoded) {
        while (true) {
            String replaced = str.replaceAll(decodePattern, "ABC[$1,$2]");
            if (replaced.equals(str)) {
                break;
            }
            str = replaced;
        }
        str = str.replaceAll("\\[", "(");
        str = str.replaceAll("\\]", ")");
        System.out.println(str);
    }

And the output is:

ABC(10,5)
ABC(ABC(20,2),5)
ABC(ABC(30,2),3+2)