title: Logical operator AND with php regular expression
body: <p>I'd like to use a kind of logical operator "AND" in my regular expression.
  I tried this:</p>
  
  <pre><code>(?=exp1)(?=exp2)
  </code></pre>
  
  <p>But in PHP <code>?=</code> doesn't work and need to write my program in PHP language. Is there another method? The expression has to match if there are present all the conditions and in any order.
  I don't wanna write every permutation like:</p>
  
  <pre><code>(exp1)(exp2)(exp3)|(exp1)(exp3)(exp2)|....
  </code></pre>