REGEX to match the last nested token

Question

I need to create a REGEX that will capture the last expression of the 'if' clause.

For example, given the following statement:

  if ( if( (1+1 == 2, 1, 2)), 3);

I want to match:

((1+1 == 2, 1, 2))

I tried this, but it does not work:

if\(\.*^(?!if)\)

also there can be nested parenthesis inside the last if, e.g. if ( if( ( x + y) *2 > 2, 1, 2)), 3); — H H, Apr 29 '21 at 14:56

Arvind Kumar Avinash · Answer 1 · 2021-04-29T15:08:28.220

4

You can use the following regex:

if\(\s*\([^()]*\)\)

RegEx Demo

import java.util.regex.Matcher;
import java.util.regex.Pattern;

public class Main {
    public static void main(String args[]) {
        Matcher matcher = Pattern.compile("if\\(\\s*\\([^()]*\\)\\)").matcher("if ( if( (1+1 == 2, 1, 2)), 3);");
        if (matcher.find()) {
            System.out.println(matcher.group());
        }
    }
}

Output:

if( (1+1 == 2, 1, 2))

Explanation of the regex from regex101:

edited Apr 29 '21 at 15:08

answered Apr 29 '21 at 15:02

Arvind Kumar Avinash

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2

please check my comment to the question, this regex also don't work with nested parentheses – H H Apr 29 '21 at 15:12
but thanks for trying to help! – H H Apr 29 '21 at 15:12

score 0 · Answer 2 · answered Apr 29 '21 at 14:46

0

This regexp runs , the result is in in group 1 ( $1 )

^if\s?((.),.);$

answered Apr 29 '21 at 14:46

hgregoire

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i tried to run it on https://regex101.com/ but a test also failed – H H Apr 29 '21 at 15:01

REGEX to match the last nested token

2 Answers2