comparison vendor/psy/psysh/src/CodeCleaner/PassableByReferencePass.php @ 0:c75dbcec494b

Initial commit from drush-created site

+<?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;
+use PhpParser\Node\Expr\ClassConstFetch;
+use PhpParser\Node\Expr\FuncCall;
+use PhpParser\Node\Expr\MethodCall;
+use PhpParser\Node\Expr\PropertyFetch;
+use PhpParser\Node\Expr\StaticCall;
+use PhpParser\Node\Expr\Variable;
+use Psy\Exception\FatalErrorException;
+
+/**
+ * Validate that only variables (and variable-like things) are passed by reference.
+ */
+class PassableByReferencePass extends CodeCleanerPass
+{
+    const EXCEPTION_MESSAGE = 'Only variables can be passed by reference';
+
+    /**
+     * @throws FatalErrorException if non-variables are passed by reference
+     *
+     * @param Node $node
+     */
+    public function enterNode(Node $node)
+    {
+        // @todo support MethodCall and StaticCall as well.
+        if ($node instanceof FuncCall) {
+            // if function name is an expression or a variable, give it a pass for now.
+            if ($node->name instanceof Expr || $node->name instanceof Variable) {
+                return;
+            }
+
+            $name = (string) $node->name;
+
+            if ($name === 'array_multisort') {
+                return $this->validateArrayMultisort($node);
+            }
+
+            try {
+                $refl = new \ReflectionFunction($name);
+            } catch (\ReflectionException $e) {
+                // Well, we gave it a shot!
+                return;
+            }
+
+            foreach ($refl->getParameters() as $key => $param) {
+                if (array_key_exists($key, $node->args)) {
+                    $arg = $node->args[$key];
+                    if ($param->isPassedByReference() && !$this->isPassableByReference($arg)) {
+                        throw new FatalErrorException(self::EXCEPTION_MESSAGE, 0, E_ERROR, null, $node->getLine());
+                    }
+                }
+            }
+        }
+    }
+
+    private function isPassableByReference(Node $arg)
+    {
+        // FuncCall, MethodCall and StaticCall are all PHP _warnings_ not fatal errors, so we'll let
+        // PHP handle those ones :)
+        return $arg->value instanceof ClassConstFetch ||
+            $arg->value instanceof PropertyFetch ||
+            $arg->value instanceof Variable ||
+            $arg->value instanceof FuncCall ||
+            $arg->value instanceof MethodCall ||
+            $arg->value instanceof StaticCall;
+    }
+
+    /**
+     * Because array_multisort has a problematic signature...
+     *
+     * The argument order is all sorts of wonky, and whether something is passed
+     * by reference or not depends on the values of the two arguments before it.
+     * We'll do a good faith attempt at validating this, but err on the side of
+     * permissive.
+     *
+     * This is why you don't design languages where core code and extensions can
+     * implement APIs that wouldn't be possible in userland code.
+     *
+     * @throws FatalErrorException for clearly invalid arguments
+     *
+     * @param Node $node
+     */
+    private function validateArrayMultisort(Node $node)
+    {
+        $nonPassable = 2; // start with 2 because the first one has to be passable by reference
+        foreach ($node->args as $arg) {
+            if ($this->isPassableByReference($arg)) {
+                $nonPassable = 0;
+            } elseif (++$nonPassable > 2) {
+                // There can be *at most* two non-passable-by-reference args in a row. This is about
+                // as close as we can get to validating the arguments for this function :-/
+                throw new FatalErrorException(self::EXCEPTION_MESSAGE, 0, E_ERROR, null, $node->getLine());
+            }
+        }
+    }
+}