php给一组指定关键词添加span标签的方法

// Example use: $spanned = codeWords($string_containing_keywords);
// My site: andrew.dx.am
// Using colour==blue,but different arrays of words and different 
// colours can be added.
function onlyWholeWords(&$value,$key) {
// Ignores words after // comment delimiters.
//$value = "/b(" . $value . ")b/";  // doesn't handle comments
//$value = "/^(?:(?!//).)*Kb(" . $value . ")b/"; 
// K lookbehind alternative is not supported in PHP < 5.2.4,so use:
  $value = "/^((?:(?!//).)*)b" . $value . "b/";
}
function addSpan(&$value,$key,$color='blue') {
  $value = "$1<span style='color:$color'>" . $value . "</span>";
}
function codeWords($code) {
  $keywords = array('as','break','case','class','continue','default','do','elif','else','elseif','for','foreach','function','if','new','null','return','self','switch','this','to','typeof','until','var','void','while','with');
  $keywords2 = $keywords;
  array_walk($keywords,'onlyWholeWords');
  array_walk($keywords2,'addSpan','blue');
  $code = preg_replace($keywords,$keywords2,$code);
  return $code;
}