Check if array of Objects contains second array of Objects

Question

I need to check if an array of DOMNode objects contains all the items in a similar array of DOMNode objects.

In general, to check if an array contains another array, I've tried some of the methods outlined in this question. However, both array_intersect() and array_diff() compare array items on the bases (string) $elem1 === (string) $elem2 - which throws the following error for DOMElements as they can't be converted to strings.

PHP Catchable fatal error: 
Object of class DOMElement could not be converted to string in...

What would be the proper way of handling this?

Answer 1

I've made this which seems to work, as example i filled both arrays with all kinds of objects and types just to see if it works:

$array = array(new DOMDocument(), 'foobar', 112312, new DateTime('Y'));
$array2 = array(new DOMDocument(), 'foobar',12312, false, new DateTime('Y'), 112312, true);

var_dump(array_diff_two($array,$array2)); //returns true

$array = array(new DOMDocument(), 'foobar', 112312, new DateTime('m'));
$array2 = array(new DOMDocument(), 'lorem ipsum!',12312, false, new DateTime('Y'), 112312, true);

var_dump(array_diff_two($array,$array2)); //returns false

function array_diff_two($array1, $array2){
    // serialize all values from array 2 which we will check if they contain values from array 1
    $serialized2 = array();
    foreach ($array2 as $value){
        $serialized2[] = serialize($value);
    }

    // Check if all values from array 1 are in 2, return false if it's not found
    foreach ($array1 as $value) {
        if (! in_array(serialize($value), $serialized2)) {
            return false;
        }
    }
    return true;
}

Answer 2

As I've written it now, here's an alternative solution. Tim's solution is more readable, in my opinion.

//Does array of DOMNodes contain other array DOMNodes
private function array_contains_array($haystack,$needle){
    //Create object hash array of $haystack
    $haystackHashArr = array();
    foreach ($haystack as $idx => $haystackObj) {
        $haystackHashArr[$idx] = spl_object_hash($haystackObj);
    }

    //Now search for hashes of needle array objects in Haystack-hash-Array
    foreach ($needle as $domNode) {
        $huntedForHash = spl_object_hash($domNode);
        foreach($haystackHashArr as $hsHash){
            if ($hsHash == $huntedForHash) continue 2;
        }
        //Only get here if an item not found (Due to continue statement)
        return false;
    }
    return true;
}