php: dom order nodes

order.php

<?php
$xml = "<?xml version=\"1.0\" encoding=\"UTF-8\"?>
<root>
        <zone type=\"zone_right\">
                a
        </zone>
        <zone type=\"zone_right\">
                b
        </zone>

        <zone type=\"zone_left\">
                c
        </zone>
</root>";

$dom = orderDom($xml);
echo $dom->saveXML();

// zone_right, zone_left-aren antzean jarri
function orderDom($xml)
{
	$dom = new DOMDocument('1.0', 'utf-8');
	$dom->loadXML($xml);

	$root = $dom->getElementsByTagName('root')->item(0);
	$zones = $root->getElementsByTagName('zone');

	for($i=0;$i<$zones->length;$i++)
	{
		$type = $zones->item($i)->getAttribute('type');
		if($type==='zone_right')
		{
			$j = $i+1;
			if($j<$zones->length)
			{
				$next_type = $zones->item($j)->getAttribute('type');
				if($next_type==='zone_left')
				{
					$parent = $zones->item($j)->parentNode;

					// zone left clonatu
					$tmp = $zones->item($j)->cloneNode(true);
					// zone right-en aurrean jarri
					$parent->insertBefore($tmp, $zones->item($i));
					// indizea + 1, insertBefore egiterakoan indizeak aldatu egiten dira, nodo 1 gehiago sartu dugulako
					// zone left originala ezabatu
					$parent->removeChild($zones->item($j+1));
					return orderDom($dom->saveXML());
				}
			}
		}
	}

	return $dom;
}

/* output:
<?xml version="1.0" encoding="UTF-8"?>
<root>
        <zone type="zone_left">
                c
        </zone><zone type="zone_right">
                a
        </zone>
        <zone type="zone_right">
                b
        </zone>
</root>
*/