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vendor/psy/psysh/src/CodeCleaner/IssetPass.php

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+<?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\Isset_;
+use PhpParser\Node\Expr\NullsafePropertyFetch;
+use PhpParser\Node\Expr\PropertyFetch;
+use PhpParser\Node\Expr\Variable;
+use Psy\Exception\FatalErrorException;
+
+/**
+ * Code cleaner pass to ensure we only allow variables, array fetch and property
+ * fetch expressions in isset() calls.
+ */
+class IssetPass extends CodeCleanerPass
+{
+    const EXCEPTION_MSG = 'Cannot use isset() on the result of an expression (you can use "null !== expression" instead)';
+
+    /**
+     * @throws FatalErrorException
+     *
+     * @param Node $node
+     *
+     * @return int|Node|null Replacement node (or special return value)
+     */
+    public function enterNode(Node $node)
+    {
+        if (!$node instanceof Isset_) {
+            return;
+        }
+
+        foreach ($node->vars as $var) {
+            if (!$var instanceof Variable && !$var instanceof ArrayDimFetch && !$var instanceof PropertyFetch && !$var instanceof NullsafePropertyFetch) {
+                throw new FatalErrorException(self::EXCEPTION_MSG, 0, \E_ERROR, null, $node->getLine());
+            }
+        }
+    }
+}