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    <h3>Editing: Session.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php

/*
 * This file is part of the Symfony package.
 *
 * (c) Fabien Potencier &lt;fabien@symfony.com&gt;
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Symfony\Component\HttpFoundation\Session;

use Symfony\Component\HttpFoundation\Session\Attribute\AttributeBag;
use Symfony\Component\HttpFoundation\Session\Attribute\AttributeBagInterface;
use Symfony\Component\HttpFoundation\Session\Flash\FlashBag;
use Symfony\Component\HttpFoundation\Session\Flash\FlashBagInterface;
use Symfony\Component\HttpFoundation\Session\Storage\NativeSessionStorage;
use Symfony\Component\HttpFoundation\Session\Storage\SessionStorageInterface;

// Help opcache.preload discover always-needed symbols
class_exists(AttributeBag::class);
class_exists(FlashBag::class);
class_exists(SessionBagProxy::class);

/**
 * @author Fabien Potencier &lt;fabien@symfony.com&gt;
 * @author Drak &lt;drak@zikula.org&gt;
 *
 * @implements \IteratorAggregate&lt;string, mixed&gt;
 */
class Session implements SessionInterface, \IteratorAggregate, \Countable
{
    protected $storage;

    private $flashName;
    private $attributeName;
    private $data = [];
    private $usageIndex = 0;
    private $usageReporter;

    public function __construct(?SessionStorageInterface $storage = null, ?AttributeBagInterface $attributes = null, ?FlashBagInterface $flashes = null, ?callable $usageReporter = null)
    {
        $this-&gt;storage = $storage ?? new NativeSessionStorage();
        $this-&gt;usageReporter = $usageReporter;

        $attributes = $attributes ?? new AttributeBag();
        $this-&gt;attributeName = $attributes-&gt;getName();
        $this-&gt;registerBag($attributes);

        $flashes = $flashes ?? new FlashBag();
        $this-&gt;flashName = $flashes-&gt;getName();
        $this-&gt;registerBag($flashes);
    }

    /**
     * {@inheritdoc}
     */
    public function start()
    {
        return $this-&gt;storage-&gt;start();
    }

    /**
     * {@inheritdoc}
     */
    public function has(string $name)
    {
        return $this-&gt;getAttributeBag()-&gt;has($name);
    }

    /**
     * {@inheritdoc}
     */
    public function get(string $name, $default = null)
    {
        return $this-&gt;getAttributeBag()-&gt;get($name, $default);
    }

    /**
     * {@inheritdoc}
     */
    public function set(string $name, $value)
    {
        $this-&gt;getAttributeBag()-&gt;set($name, $value);
    }

    /**
     * {@inheritdoc}
     */
    public function all()
    {
        return $this-&gt;getAttributeBag()-&gt;all();
    }

    /**
     * {@inheritdoc}
     */
    public function replace(array $attributes)
    {
        $this-&gt;getAttributeBag()-&gt;replace($attributes);
    }

    /**
     * {@inheritdoc}
     */
    public function remove(string $name)
    {
        return $this-&gt;getAttributeBag()-&gt;remove($name);
    }

    /**
     * {@inheritdoc}
     */
    public function clear()
    {
        $this-&gt;getAttributeBag()-&gt;clear();
    }

    /**
     * {@inheritdoc}
     */
    public function isStarted()
    {
        return $this-&gt;storage-&gt;isStarted();
    }

    /**
     * Returns an iterator for attributes.
     *
     * @return \ArrayIterator&lt;string, mixed&gt;
     */
    #[\ReturnTypeWillChange]
    public function getIterator()
    {
        return new \ArrayIterator($this-&gt;getAttributeBag()-&gt;all());
    }

    /**
     * Returns the number of attributes.
     *
     * @return int
     */
    #[\ReturnTypeWillChange]
    public function count()
    {
        return \count($this-&gt;getAttributeBag()-&gt;all());
    }

    public function &amp;getUsageIndex(): int
    {
        return $this-&gt;usageIndex;
    }

    /**
     * @internal
     */
    public function isEmpty(): bool
    {
        if ($this-&gt;isStarted()) {
            ++$this-&gt;usageIndex;
            if ($this-&gt;usageReporter &amp;&amp; 0 &lt;= $this-&gt;usageIndex) {
                ($this-&gt;usageReporter)();
            }
        }
        foreach ($this-&gt;data as &amp;$data) {
            if (!empty($data)) {
                return false;
            }
        }

        return true;
    }

    /**
     * {@inheritdoc}
     */
    public function invalidate(?int $lifetime = null)
    {
        $this-&gt;storage-&gt;clear();

        return $this-&gt;migrate(true, $lifetime);
    }

    /**
     * {@inheritdoc}
     */
    public function migrate(bool $destroy = false, ?int $lifetime = null)
    {
        return $this-&gt;storage-&gt;regenerate($destroy, $lifetime);
    }

    /**
     * {@inheritdoc}
     */
    public function save()
    {
        $this-&gt;storage-&gt;save();
    }

    /**
     * {@inheritdoc}
     */
    public function getId()
    {
        return $this-&gt;storage-&gt;getId();
    }

    /**
     * {@inheritdoc}
     */
    public function setId(string $id)
    {
        if ($this-&gt;storage-&gt;getId() !== $id) {
            $this-&gt;storage-&gt;setId($id);
        }
    }

    /**
     * {@inheritdoc}
     */
    public function getName()
    {
        return $this-&gt;storage-&gt;getName();
    }

    /**
     * {@inheritdoc}
     */
    public function setName(string $name)
    {
        $this-&gt;storage-&gt;setName($name);
    }

    /**
     * {@inheritdoc}
     */
    public function getMetadataBag()
    {
        ++$this-&gt;usageIndex;
        if ($this-&gt;usageReporter &amp;&amp; 0 &lt;= $this-&gt;usageIndex) {
            ($this-&gt;usageReporter)();
        }

        return $this-&gt;storage-&gt;getMetadataBag();
    }

    /**
     * {@inheritdoc}
     */
    public function registerBag(SessionBagInterface $bag)
    {
        $this-&gt;storage-&gt;registerBag(new SessionBagProxy($bag, $this-&gt;data, $this-&gt;usageIndex, $this-&gt;usageReporter));
    }

    /**
     * {@inheritdoc}
     */
    public function getBag(string $name)
    {
        $bag = $this-&gt;storage-&gt;getBag($name);

        return method_exists($bag, 'getBag') ? $bag-&gt;getBag() : $bag;
    }

    /**
     * Gets the flashbag interface.
     *
     * @return FlashBagInterface
     */
    public function getFlashBag()
    {
        return $this-&gt;getBag($this-&gt;flashName);
    }

    /**
     * Gets the attributebag interface.
     *
     * Note that this method was added to help with IDE autocompletion.
     */
    private function getAttributeBag(): AttributeBagInterface
    {
        return $this-&gt;getBag($this-&gt;attributeName);
    }
}
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