SimpleXMLElementXpathObject.php

<?php
/**
 * Class SimpleXMLElementXpathObject
 *
 * Object properties are mapped to Xpath queries
 */
class SimpleXMLElementXpathObject implements IteratorAggregate, JsonSerializable
{
    private $anchor;
    private $props;

    public function __construct(SimpleXMLElement $anchor, array $props) {
        $this->anchor = $anchor;
        $this->props  = $props;
    }

    public function __isset($name) {
        if (!isset($this->props[$name])) {
            return false;
        }
        return null !== $this->getXpathProp($name);
    }

    public function __get($name) {
        if (!isset($this->props[$name])) {
            trigger_error(sprintf('Undefined property %s', $name));
            return NULL;
        }
        return $this->getXpathProp($name);
    }

    private function getXpathProp($name) {
        $xpath = $this->props[$name];
        $result = $this->anchor->xpath($xpath);
        if ($result === FALSE) {
            return $result;
        }
        if ($result) {
            return $result[0];
        }
        return NULL;
    }

    public function getIterator() {
        return new PropertyIterator($this, array_keys($this->props));
    }

    public function getArrayCopy() {
        return iterator_to_array($this);
    }

    public function jsonSerialize() {
        return (object)array_map('strval', $this->getArrayCopy());
    }
}