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

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+<?php
+
+/*
+ * This file is part of Psy Shell.
+ *
+ * (c) 2012-2025 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\ArrayItem;
+use PhpParser\Node\Expr\Array_;
+use PhpParser\Node\Expr\ArrayDimFetch;
+// @todo Drop PhpParser\Node\Expr\ArrayItem once we drop support for PHP-Parser 4.x
+use PhpParser\Node\Expr\ArrayItem as LegacyArrayItem;
+use PhpParser\Node\Expr\Assign;
+use PhpParser\Node\Expr\FuncCall;
+use PhpParser\Node\Expr\List_;
+use PhpParser\Node\Expr\MethodCall;
+use PhpParser\Node\Expr\PropertyFetch;
+use PhpParser\Node\Expr\Variable;
+use Psy\Exception\ParseErrorException;
+
+/**
+ * Validate that the list assignment.
+ */
+class ListPass extends CodeCleanerPass
+{
+    /**
+     * Validate use of list assignment.
+     *
+     * @throws ParseErrorException if the user used empty with anything but a variable
+     *
+     * @param Node $node
+     *
+     * @return int|Node|null Replacement node (or special return value)
+     */
+    public function enterNode(Node $node)
+    {
+        if (!$node instanceof Assign) {
+            return null;
+        }
+
+        if (!$node->var instanceof Array_ && !$node->var instanceof List_) {
+            return null;
+        }
+
+        // Polyfill for PHP-Parser 2.x
+        $items = isset($node->var->items) ? $node->var->items : (\property_exists($node->var, 'vars') ? $node->var->vars : []);
+
+        if ($items === [] || $items === [null]) {
+            throw new ParseErrorException('Cannot use empty list', ['startLine' => $node->var->getStartLine(), 'endLine' => $node->var->getEndLine()]);
+        }
+
+        $itemFound = false;
+        foreach ($items as $item) {
+            if ($item === null) {
+                continue;
+            }
+
+            $itemFound = true;
+
+            if (!self::isValidArrayItem($item)) {
+                $msg = 'Assignments can only happen to writable values';
+                throw new ParseErrorException($msg, ['startLine' => $item->getStartLine(), 'endLine' => $item->getEndLine()]);
+            }
+        }
+
+        if (!$itemFound) {
+            throw new ParseErrorException('Cannot use empty list');
+        }
+
+        return null;
+    }
+
+    /**
+     * Validate whether a given item in an array is valid for short assignment.
+     *
+     * @param Node $item
+     */
+    private static function isValidArrayItem(Node $item): bool
+    {
+        $value = ($item instanceof ArrayItem || $item instanceof LegacyArrayItem) ? $item->value : $item;
+
+        while ($value instanceof ArrayDimFetch || $value instanceof PropertyFetch) {
+            $value = $value->var;
+        }
+
+        // We just kind of give up if it's a method call. We can't tell if it's
+        // valid via static analysis.
+        return $value instanceof Variable || $value instanceof MethodCall || $value instanceof FuncCall;
+    }
+}