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

/*
 * This file is part of Psy Shell.
 *
 * (c) 2012-2023 Justin Hileman
 *
 * For the full copyright and license information, please view the LICENSE
 * file that was distributed with this source code.
 */

namespace Psy\CodeCleaner;

use PhpParser\Node;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Expr\Variable;
use Psy\Exception\FatalErrorException;

/**
 * Validate that the user input does not assign the `$this` variable.
 *
 * @author Martin Hasoň &lt;martin.hason@gmail.com&gt;
 */
class AssignThisVariablePass extends CodeCleanerPass
{
    /**
     * Validate that the user input does not assign the `$this` variable.
     *
     * @throws FatalErrorException if the user assign the `$this` variable
     *
     * @param Node $node
     *
     * @return int|Node|null Replacement node (or special return value)
     */
    public function enterNode(Node $node)
    {
        if ($node instanceof Assign &amp;&amp; $node-&gt;var instanceof Variable &amp;&amp; $node-&gt;var-&gt;name === 'this') {
            throw new FatalErrorException('Cannot re-assign $this', 0, \E_ERROR, null, $node-&gt;getStartLine());
        }
    }
}
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