XML represents as array

xml_tools.php

<?php
define('XML_RETURN_DOM_ELEMENT', 1);
define('XML_WITHOUT_DECLARATION', 2);
define('XML_PRETTY_PRINT', 4);

function xml_decode($node) {
    $node   = is_string($node) ? new \SimpleXMLElement($node) : $node;
    $result = ['tag' => $node->getName()];
    foreach ($node->attributes() as $name => $value) {
        $value = (array) $value;
        $result['@' . $name] = $value[0];
    }
    $result['children'] = [];
    foreach ($node->children() as $name => $child) {
        $result['children'][] = xml_decode($child);
    }

    return $result;
}

function xml_encode($node, $param = 0) {
    $node     = array_merge(['tag' => 'root', 'children' => []], $node);
    $document = new \DOMDocument();
    $result   = $document->createElement($node['tag']);
    foreach ($node as $name => $value) {
        if (substr($name, 0, 1) != '@') continue;
        $result->setAttribute(substr($name, 1), $value);
    }
    foreach ($node['children'] as $child) {
        $child = xml_encode($child, XML_RETURN_DOM_ELEMENT);
        $result->appendChild($document->importNode($child, true));
    }

    if ($param & XML_RETURN_DOM_ELEMENT) {
        return $result;
    }

    $document->appendChild($result);
    if ($param & XML_PRETTY_PRINT) {
        $document->formatOutput = true;
    }
    
    $result = $document->saveXML();
    if ($param & XML_WITHOUT_DECLARATION) {
        $result = str_replace("<?xml version=\"1.0\"?>\n", '', $result);
    }
    return $result;
}