--- /dev/null
+<?php
+
+/*
+ * This file is part of Psy Shell.
+ *
+ * (c) 2012-2018 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\Array_;
+use PhpParser\Node\Expr\ArrayItem;
+use PhpParser\Node\Expr\Assign;
+use PhpParser\Node\Expr\List_;
+use PhpParser\Node\Expr\Variable;
+use Psy\Exception\ParseErrorException;
+
+/**
+ * Validate that the list assignment.
+ */
+class ListPass extends CodeCleanerPass
+{
+ private $atLeastPhp71;
+
+ public function __construct()
+ {
+ $this->atLeastPhp71 = version_compare(PHP_VERSION, '7.1', '>=');
+ }
+
+ /**
+ * Validate use of list assignment.
+ *
+ * @throws ParseErrorException if the user used empty with anything but a variable
+ *
+ * @param Node $node
+ */
+ public function enterNode(Node $node)
+ {
+ if (!$node instanceof Assign) {
+ return;
+ }
+
+ if (!$node->var instanceof Array_ && !$node->var instanceof List_) {
+ return;
+ }
+
+ if (!$this->atLeastPhp71 && $node->var instanceof Array_) {
+ $msg = "syntax error, unexpected '='";
+ throw new ParseErrorException($msg, $node->expr->getLine());
+ }
+
+ // Polyfill for PHP-Parser 2.x
+ $items = isset($node->var->items) ? $node->var->items : $node->var->vars;
+
+ if ($items === [] || $items === [null]) {
+ throw new ParseErrorException('Cannot use empty list', $node->var->getLine());
+ }
+
+ foreach ($items as $item) {
+ if ($item === null) {
+ throw new ParseErrorException('Cannot use empty list', $item->getLine());
+ }
+
+ // List_->$vars in PHP-Parser 2.x is Variable instead of ArrayItem.
+ if (!$this->atLeastPhp71 && $item instanceof ArrayItem && $item->key !== null) {
+ $msg = 'Syntax error, unexpected T_CONSTANT_ENCAPSED_STRING, expecting \',\' or \')\'';
+ throw new ParseErrorException($msg, $item->key->getLine());
+ }
+
+ $value = ($item instanceof ArrayItem) ? $item->value : $item;
+
+ if (!$value instanceof Variable) {
+ $msg = 'Assignments can only happen to writable values';
+ throw new ParseErrorException($msg, $item->getLine());
+ }
+ }
+ }
+}