Simulating using/with in PHP

using.php

<?php

class Singleton // https://github.com/Trismegiste/Php-Is-Magic
{
    public static function getInstance()
    {
        static $instances = array();
        $key = get_called_class();
        if (!array_key_exists($key, $instances)) {
            $instances[$key] = new $key();
        }
        return $instances[$key];
    }
    private function __construct() {}
    private function __clone() {}
    public function __wakeup() {}
}

###############################################################################

abstract class State extends Singleton {
    private $stack = array();

    public function push($value) {
        if (count($this->stack) === 0) {
            $this->stack[] = $value;
        } else {
            $top = $this->top();
            if (!$this->supports($top)) {
                throw new \LogicException();
            }
            $data = $this->get($top, $value);
            $this->stack[] = $data;
        }
    }

    public function pop() {
        array_pop($this->stack);
    }

    public function top() {
        $num = count($this->stack) - 1;
        $top = $this->stack[$num];
        return $top;
    }

    abstract public function supports($value);

    abstract public function get($parent, $value);
}

class ObjectState extends State {
    public function supports($value) {
        return is_object($value);
    }
    public function get($parent, $value) {
        return $parent->$value;
    }
}

###############################################################################

function using(&$variable) {
    $state = ObjectState::getInstance();
    $state->push($variable);
    yield this();
    $state->pop();
}

function with($property) {
    $state = ObjectState::getInstance();
    $state->push($property);
    yield this();
    $state->pop();
}

function this() {
    return ObjectState::getInstance()->top();
}

###############################################################################

class PersonLikes extends \ArrayObject {};
class Person {
    public $name;
    public $likes;
    public function __construct($name, array $likes = array()) {
        $this->name = $name;
        $this->likes = new PersonLikes($likes);
    }
}

$person = new Person('John', ['Rugby', 'Bananas']);

###############################################################################

foreach (using($person) as $_) {
    echo this()->name;
    echo ' likes ';
    foreach (with('likes') as $_) {
        $_[] = 'PHP'; // Add PHP to likes
        echo implode(', ', (array) this());
    }
    echo '.';
    echo PHP_EOL;
}