Regex / DOMDocument - match and replace text not in a link

Question

I need to find and replace all text matches in a case insensitive way, unless the text is within an anchor tag - for example:

Match this text and re         


        

Answer 1

This is the stackless non-recursive approach using pre-order traversal of the DOM tree.

  libxml_use_internal_errors(TRUE);
  $dom=new DOMDocument('1.0','UTF-8');

  $dom->substituteEntities=FALSE;
  $dom->recover=TRUE;
  $dom->strictErrorChecking=FALSE;

  $dom->loadHTMLFile($file);
  $root=$dom->documentElement;
  $node=$root;
  $flag=FALSE;
  for (;;) {
      if (!$flag) {
          if ($node->nodeType==XML_TEXT_NODE &&
              $node->parentNode->tagName!='a') {
              $node->nodeValue=preg_replace(
                  '/match this text/is',
                  $replacement, $node->nodeValue
              );
          }
          if ($node->firstChild) {
              $node=$node->firstChild;
              continue;
          }
     }
     if ($node->isSameNode($root)) break;
     if ($flag=$node->nextSibling)
          $node=$node->nextSibling;
     else
          $node=$node->parentNode;
 }
 echo $dom->saveHTML();

libxml_use_internal_errors(TRUE); and the 3 lines of code after $dom=new DOMDocument; should be able to handle any malformed HTML.