Question

I need a regex in php that allows the following:

here is the given example
1. aaa aaa{bb b {c cc}{d dd}e ee}xxx
2. 123{asd{asd{asd{asd}asd}}asd}qwe

the output will be:
1. {bb b {c cc}{d dd}e ee}
2. {asd{asd{asd{asd}asd}}asd}

I tried this but does not work

preg_match_all('/{(.*?)}/', $resonse, $matches);

its basically getting rid of anything outside the main curly braces eventhought there are curly braces inside of it. I really need you help. thanks so much.

Answer 1

You will need PCRE’s recursion capabilities to do this.

<?php
$pattern = '!
  { # patterns start with curly brace
      (?:           # ?: means that this is only for grouping, not for capturing
                    # the { } contain 
        [^{}]*      # not-curly-braces-characters
      |             # or
        (?R)        # this pattern again, i.e. {^[{}] | (?R) } again
      )*
  } # patterns ends with curly brace
!x';

foreach( array('aaa aaa{bb b {c cc}{d dd}e ee}xxx', '123{asd{asd{asd{asd}asd}}asd}qwe') as $subject ) {
    echo "\n$subject: ";
    if ( preg_match($pattern, $subject, $m) ) {
        echo $m[0];
    }
    else {
        echo '--no match--';
    }
}

prints

aaa aaa{bb b {c cc}{d dd}e ee}xxx: {bb b {c cc}{d dd}e ee}
123{asd{asd{asd{asd}asd}}asd}qwe: {asd{asd{asd{asd}asd}}asd}