Finds an extract from a string (n) words before a matched word and highlights any occurrences

HighlightExtract.php

/**
 * $str to search
 * $query word to search for
 * $words either side of first match to return
 */
 
  function highlightedExtract($str, $query, $words) {
      $pos = stripos($str,$query);
      $after = substr($str,$pos,$words); 
      $prior = explode($after,$str);
      $prior = '...' . substr($prior[0],-$words);
      return preg_replace("/".preg_quote($query, "/")."/i", "<span class='highlight'>$0</span>", $prior.$after).' ...';
  }