Question

program A {
   int x = 10;
   tuple date {
            int day;
            int month;
            int year;
   }
}

function B {
    int y = 20;
    ...
}

process C {
    more code;
}

I’d like to extract whatever is inside the outer curly braces for program, function and process. In terms of the output, I want to see three matches:

       int x = 10;
       tuple date {
                int day;
                int month;
                int year;
       } //first match

       int y = 20;
       ... //second match

       more code; //third match

I’ve achieved this using Javascript. The regular expression I use is /(program|function|process).*?{(.*?)}\n+(program|function|process)/m, which works as demonstrated by Rubular.

However, when I use the same expression in Java it wouldn’t work any more. It only returns the first match. I have a vague memory that the consumed text in a previous match will not be matched again. In my case, the keywords program and function have been consumed in the first match, resulting in no further matches. Is there a way in Java to match the consumed text?

Edit: the Java code is posted below as requested.

public class Test {
    public static void main(String[] args) throws IOException {
        String input = FileUtils.readFileToString(new File("input.txt"));
        Pattern p = Pattern.compile("(program|function|process)[^\\{]*?\\{(.*?)\\}\\s*(program|function|process)", Pattern.DOTALL);
        Matcher m = p.matcher(input);
        while(m.find()) {
            System.out.println(m.group(2));
        }
    }
}

Answer 1

You can solve your problem by using lookarounds..so your regex would be

(?<=program|function|process)[^{]*\\{(.*?)\\}\\s*(?=program|function|process|$) 

Group 1 would have your data..