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    <h3>Editing: EmptyArrayDimFetchPass.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\ArrayDimFetch;
use PhpParser\Node\Expr\Assign;
use PhpParser\Node\Expr\AssignRef;
use PhpParser\Node\Stmt\Foreach_;
use Psy\Exception\FatalErrorException;

/**
 * Validate empty brackets are only used for assignment.
 */
class EmptyArrayDimFetchPass extends CodeCleanerPass
{
    const EXCEPTION_MESSAGE = 'Cannot use [] for reading';

    private $theseOnesAreFine = [];

    /**
     * @return Node[]|null Array of nodes
     */
    public function beforeTraverse(array $nodes)
    {
        $this-&gt;theseOnesAreFine = [];
    }

    /**
     * @throws FatalErrorException if the user used empty array dim fetch outside of assignment
     *
     * @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 ArrayDimFetch) {
            $this-&gt;theseOnesAreFine[] = $node-&gt;var;
        } elseif ($node instanceof AssignRef &amp;&amp; $node-&gt;expr instanceof ArrayDimFetch) {
            $this-&gt;theseOnesAreFine[] = $node-&gt;expr;
        } elseif ($node instanceof Foreach_ &amp;&amp; $node-&gt;valueVar instanceof ArrayDimFetch) {
            $this-&gt;theseOnesAreFine[] = $node-&gt;valueVar;
        } elseif ($node instanceof ArrayDimFetch &amp;&amp; $node-&gt;var instanceof ArrayDimFetch) {
            // $a[]['b'] = 'c'
            if (\in_array($node, $this-&gt;theseOnesAreFine)) {
                $this-&gt;theseOnesAreFine[] = $node-&gt;var;
            }
        }

        if ($node instanceof ArrayDimFetch &amp;&amp; $node-&gt;dim === null) {
            if (!\in_array($node, $this-&gt;theseOnesAreFine)) {
                throw new FatalErrorException(self::EXCEPTION_MESSAGE, $node-&gt;getStartLine());
            }
        }
    }
}
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