Question

$list = array('br', 'hr', 'link', 'meta', 'title');

Using DOMXpath, how can I select nodes that are empty and their tagName is not within $list?
(I want to add a space in their textContent so they are not automatically closed)

Answer 1

You didn’t give us any XML to work with, which is not very nice, but here you go:

$xml = <<<XML
<div>
   <a>
   </a>
   <p>some text</p>
   <p></p>
   <span>no text
      <hr/>
      <ul></ul>
   </span>
   <br/>
</div>
XML;

$dom = new DOMDocument;
$dom->loadXML($xml);
$xpath = new DOMXPath($dom);
$list = array('br', 'hr', 'link', 'meta', 'title');
$expr = array();
foreach ($list as $l) {
   $expr[] = "not(self::$l)";
}
$expr = implode(' and ', $expr);

foreach ($xpath->query("//*[$expr and not(normalize-space())]") as $elem) {
   echo "$elem->nodeName\n";
}

This outputs

a
p
ul

As expected. Now you have the nodes — it’s up to you to add the space. IMO it would be easier to just use not(normalize-space()) and then see if the nodeName is not in your list, but you asked for an XPath expression, so that’s what you got.

Note that normalize-space() is used because pure whitespace may still cause the node to automatically close. If that’s not an issue, you can use node() instead.