How to check if dom node list already has the same node

Question

I need to get all parents of all page paragraphs and of all list items by PHP DOMDocument

Let's say, we have such html:

<div>
    <p>Some text</p>
    <p>Some text</p>
</div>
<section>
    <p>Some text</p>
    <p>Some text</p>
    <p>Some text</p>
</section>
<ul>
    <li>Item 1</li>
    <li>Item 2</li>
    <li>Item 3</li>
    <li>Item 4</li>
</ul>

If I use two following loops

$parents = [];
foreach($dom->getElementsByTagName('p') as $paragraph) {
    $parents[] = $paragraph->parentNode;
}
foreach($dom->getElementsByTagName('li') as $li) {
    $parents[] = $li->parentNode;
}

In the end I need just to add a class to each parent like

foreach($parents as $key => $parent) {
     $parent->setAttribute('class', 'prefix_'.$key);
}

and would like to get the output

<div class="prefix_0">
...
</div>
<section class="prefix_1">
...
</section>
<div class="prefix_2">
...
</div>

But I get

<div class="prefix_0 prefix_1">
...
</div>
<section class="prefix_2 prefix_3 prefix_4">
...
</section>
<div class="prefix_5 prefix_6 prefix_7 prefix_8">
...
</div>

If I add the condition

if(!in_array($paragraph->parentNode, $parents)) {

it doesn't work as I see because we have not an array but node list

So how to avoid adding the same parent?

Answer 1

Very simply function to avoid it:

function compareParentNode($compare_node,$parents){
   foreach($parents as $parent){
       if ($parent->isSameNode($compare_node)) return true;
   }
   return false;
}

Using:

$parents = [];
foreach($dom->getElementsByTagName('p') as $paragraph) {
   $parentNode = $paragraph->parentNode;
   if (!compareParentNode($parentNode,$parents)){   
      $parents[] = $paragraph->parentNode;
   }
}

See more isSameNode