Chris@13: <?php
Chris@13: 
Chris@13: /*
Chris@13:  * This file is part of Psy Shell.
Chris@13:  *
Chris@13:  * (c) 2012-2018 Justin Hileman
Chris@13:  *
Chris@13:  * For the full copyright and license information, please view the LICENSE
Chris@13:  * file that was distributed with this source code.
Chris@13:  */
Chris@13: 
Chris@13: namespace Psy\CodeCleaner;
Chris@13: 
Chris@13: use PhpParser\Node;
Chris@13: use PhpParser\Node\Expr;
Chris@13: use PhpParser\Node\Expr\ClassConstFetch;
Chris@13: use PhpParser\Node\Expr\FuncCall;
Chris@13: use PhpParser\Node\Expr\MethodCall;
Chris@13: use PhpParser\Node\Expr\PropertyFetch;
Chris@13: use PhpParser\Node\Expr\StaticCall;
Chris@13: use PhpParser\Node\Expr\Variable;
Chris@13: use Psy\Exception\FatalErrorException;
Chris@13: 
Chris@13: /**
Chris@13:  * Validate that only variables (and variable-like things) are passed by reference.
Chris@13:  */
Chris@13: class PassableByReferencePass extends CodeCleanerPass
Chris@13: {
Chris@13:     const EXCEPTION_MESSAGE = 'Only variables can be passed by reference';
Chris@13: 
Chris@13:     /**
Chris@13:      * @throws FatalErrorException if non-variables are passed by reference
Chris@13:      *
Chris@13:      * @param Node $node
Chris@13:      */
Chris@13:     public function enterNode(Node $node)
Chris@13:     {
Chris@13:         // @todo support MethodCall and StaticCall as well.
Chris@13:         if ($node instanceof FuncCall) {
Chris@13:             // if function name is an expression or a variable, give it a pass for now.
Chris@13:             if ($node->name instanceof Expr || $node->name instanceof Variable) {
Chris@13:                 return;
Chris@13:             }
Chris@13: 
Chris@13:             $name = (string) $node->name;
Chris@13: 
Chris@13:             if ($name === 'array_multisort') {
Chris@13:                 return $this->validateArrayMultisort($node);
Chris@13:             }
Chris@13: 
Chris@13:             try {
Chris@13:                 $refl = new \ReflectionFunction($name);
Chris@13:             } catch (\ReflectionException $e) {
Chris@13:                 // Well, we gave it a shot!
Chris@13:                 return;
Chris@13:             }
Chris@13: 
Chris@13:             foreach ($refl->getParameters() as $key => $param) {
Chris@17:                 if (\array_key_exists($key, $node->args)) {
Chris@13:                     $arg = $node->args[$key];
Chris@13:                     if ($param->isPassedByReference() && !$this->isPassableByReference($arg)) {
Chris@13:                         throw new FatalErrorException(self::EXCEPTION_MESSAGE, 0, E_ERROR, null, $node->getLine());
Chris@13:                     }
Chris@13:                 }
Chris@13:             }
Chris@13:         }
Chris@13:     }
Chris@13: 
Chris@13:     private function isPassableByReference(Node $arg)
Chris@13:     {
Chris@13:         // FuncCall, MethodCall and StaticCall are all PHP _warnings_ not fatal errors, so we'll let
Chris@13:         // PHP handle those ones :)
Chris@13:         return $arg->value instanceof ClassConstFetch ||
Chris@13:             $arg->value instanceof PropertyFetch ||
Chris@13:             $arg->value instanceof Variable ||
Chris@13:             $arg->value instanceof FuncCall ||
Chris@13:             $arg->value instanceof MethodCall ||
Chris@13:             $arg->value instanceof StaticCall;
Chris@13:     }
Chris@13: 
Chris@13:     /**
Chris@13:      * Because array_multisort has a problematic signature...
Chris@13:      *
Chris@13:      * The argument order is all sorts of wonky, and whether something is passed
Chris@13:      * by reference or not depends on the values of the two arguments before it.
Chris@13:      * We'll do a good faith attempt at validating this, but err on the side of
Chris@13:      * permissive.
Chris@13:      *
Chris@13:      * This is why you don't design languages where core code and extensions can
Chris@13:      * implement APIs that wouldn't be possible in userland code.
Chris@13:      *
Chris@13:      * @throws FatalErrorException for clearly invalid arguments
Chris@13:      *
Chris@13:      * @param Node $node
Chris@13:      */
Chris@13:     private function validateArrayMultisort(Node $node)
Chris@13:     {
Chris@13:         $nonPassable = 2; // start with 2 because the first one has to be passable by reference
Chris@13:         foreach ($node->args as $arg) {
Chris@13:             if ($this->isPassableByReference($arg)) {
Chris@13:                 $nonPassable = 0;
Chris@13:             } elseif (++$nonPassable > 2) {
Chris@13:                 // There can be *at most* two non-passable-by-reference args in a row. This is about
Chris@13:                 // as close as we can get to validating the arguments for this function :-/
Chris@13:                 throw new FatalErrorException(self::EXCEPTION_MESSAGE, 0, E_ERROR, null, $node->getLine());
Chris@13:             }
Chris@13:         }
Chris@13:     }
Chris@13: }