XML to Array (with namespaced elements)

_xml_to_array.php

<?php
/**
 * Given the URL of an XML file, fetch the contents and pass it to _xml_to_array() to be
 * converted to an associative array. The file is read into a string and then parsed via
 * simplexml_load_string() (rather than parsed directly with simplexml_load_file()),
 * because the "LIBXML_NOCDATA" parameter is required in order for CDATA to persist.
 */
function _xml_to_array_from_file($url) {
  $array = NULL;
  if ($file = file_get_contents($url)) {
    if ($xml = simplexml_load_string($file, 'SimpleXMLElement', LIBXML_NOCDATA)) $array = _xml_to_array($xml);
  }
  return $array;
}

/**
 * Convert XML to an associative array, including all namespaced XML elements. Simplified
 * and updated from https://outlandish.com/blog/tutorial/xml-to-json/
 */
function _xml_to_array($xml, $safe_key_prefix = '_xml_to_array') {
  $array = [];
  $name = $xml->getName();
  $namespaces = $xml->getDocNamespaces();
  $namespaces[''] = NULL;
  // Get attributes from all namespaces.
  $attributes = [];
  foreach ($namespaces as $prefix => $namespace) {
    foreach ($xml->attributes($namespace) as $attribute_name => $attribute) {
      if ($prefix) $attribute_name = "{$prefix}:{$attribute_name}";
      $attributes[$attribute_name] = (string)$attribute;
    }
  }
  // Get child nodes from all namespaces.
  $tags = [];
  foreach ($namespaces as $prefix => $namespace) {
    foreach ($xml->children($namespace) as $child_xml) {
      // Recurse into child nodes.
      $child_array = _xml_to_array($child_xml);
      $child_name = key($child_array);
      $child_properties = current($child_array);
      if ($prefix) $child_name = "{$prefix}:{$child_name}";
      if (!isset($tags[$child_name])) $tags[$child_name] = $child_properties;
      else {
        // This is a child element being added to a parent for which at least one simlar
        // child element already exists. If only one child already exists, that existing
        // child is directly under the parent, and thus needs to be converted to the first
        // item in an array of children before the current element can be appended. In
        // order to determine if this is the case, check if the key of the first child of
        // the parent is "0", which indicates that there is already an array of children.
        // If there's not already an array of children, the first key will be the key of
        // an element within the lone child (e.g., "['title' => ...]").
        if (array_key_first($tags[$child_name]) !== 0) $tags[$child_name] = [0 => $tags[$child_name]];
        $tags[$child_name][] = $child_properties;
      }
    }
  }
  // Get the content of the node.
  $content = [];
  $content_string = trim((string)$xml);
  if ($content_string !== '') $content["{$safe_key_prefix}_content"] = $content_string;
  if (!empty($attributes) || (!empty($tags)) || ($content_string === '')) $properties = array_merge($attributes, $tags, $content);
  else $properties = $content_string;
  $array[$name] = $properties;
  return $array;
}