<?php

/*
 * This file is part of Psy Shell.
 *
 * (c) 2012-2015 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 as Node;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Expr\Variable;
use Psy\Exception\FatalErrorException;

/**
 * Validate that the user input does not assign the `$this` variable.
 *
 * @author Martin Hasoň <martin.hason@gmail.com>
 */
class AssignThisVariablePass extends CodeCleanerPass
{
    /**
     * Validate that the user input does not assign the `$this` variable.
     *
     * @throws RuntimeException if the user assign the `$this` variable.
     *
     * @param Node $node
     */
    public function enterNode(Node $node)
    {
        if ($node instanceof Assign && $node->var instanceof Variable && $node->var->name === 'this') {
            throw new FatalErrorException('Cannot re-assign $this');
        }
    }
}
