<?php
$input = <<<INP
value that I {want}, vs value "I do {NOT} want".
Lets make it's {nested {this {time}}} what's
And yes, it's even "{bullet-{proof}}" whats :)
INP;
@preg_match_all('~("|\').*?\1(*SKIP)(*FAIL)|\{(?:[^{}]|(?R))*\}~', $input, $m);
print_r($m[0]);
?>