Chris@0: <?php declare(strict_types=1);
Chris@0: 
Chris@0: namespace PhpParser;
Chris@0: 
Chris@0: class NodeTraverser implements NodeTraverserInterface
Chris@0: {
Chris@0:     /**
Chris@0:      * If NodeVisitor::enterNode() returns DONT_TRAVERSE_CHILDREN, child nodes
Chris@0:      * of the current node will not be traversed for any visitors.
Chris@0:      *
Chris@0:      * For subsequent visitors enterNode() will still be called on the current
Chris@0:      * node and leaveNode() will also be invoked for the current node.
Chris@0:      */
Chris@0:     const DONT_TRAVERSE_CHILDREN = 1;
Chris@0: 
Chris@0:     /**
Chris@0:      * If NodeVisitor::enterNode() or NodeVisitor::leaveNode() returns
Chris@0:      * STOP_TRAVERSAL, traversal is aborted.
Chris@0:      *
Chris@0:      * The afterTraverse() method will still be invoked.
Chris@0:      */
Chris@0:     const STOP_TRAVERSAL = 2;
Chris@0: 
Chris@0:     /**
Chris@0:      * If NodeVisitor::leaveNode() returns REMOVE_NODE for a node that occurs
Chris@0:      * in an array, it will be removed from the array.
Chris@0:      *
Chris@0:      * For subsequent visitors leaveNode() will still be invoked for the
Chris@0:      * removed node.
Chris@0:      */
Chris@0:     const REMOVE_NODE = 3;
Chris@0: 
Chris@4:     /**
Chris@4:      * If NodeVisitor::enterNode() returns DONT_TRAVERSE_CURRENT_AND_CHILDREN, child nodes
Chris@4:      * of the current node will not be traversed for any visitors.
Chris@4:      *
Chris@4:      * For subsequent visitors enterNode() will not be called as well.
Chris@4:      * leaveNode() will be invoked for visitors that has enterNode() method invoked.
Chris@4:      */
Chris@4:     const DONT_TRAVERSE_CURRENT_AND_CHILDREN = 4;
Chris@4: 
Chris@0:     /** @var NodeVisitor[] Visitors */
Chris@4:     protected $visitors = [];
Chris@0: 
Chris@0:     /** @var bool Whether traversal should be stopped */
Chris@0:     protected $stopTraversal;
Chris@0: 
Chris@0:     public function __construct() {
Chris@4:         // for BC
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Adds a visitor.
Chris@0:      *
Chris@0:      * @param NodeVisitor $visitor Visitor to add
Chris@0:      */
Chris@0:     public function addVisitor(NodeVisitor $visitor) {
Chris@0:         $this->visitors[] = $visitor;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Removes an added visitor.
Chris@0:      *
Chris@0:      * @param NodeVisitor $visitor
Chris@0:      */
Chris@0:     public function removeVisitor(NodeVisitor $visitor) {
Chris@0:         foreach ($this->visitors as $index => $storedVisitor) {
Chris@0:             if ($storedVisitor === $visitor) {
Chris@0:                 unset($this->visitors[$index]);
Chris@0:                 break;
Chris@0:             }
Chris@0:         }
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Traverses an array of nodes using the registered visitors.
Chris@0:      *
Chris@0:      * @param Node[] $nodes Array of nodes
Chris@0:      *
Chris@0:      * @return Node[] Traversed array of nodes
Chris@0:      */
Chris@0:     public function traverse(array $nodes) : array {
Chris@0:         $this->stopTraversal = false;
Chris@0: 
Chris@0:         foreach ($this->visitors as $visitor) {
Chris@0:             if (null !== $return = $visitor->beforeTraverse($nodes)) {
Chris@0:                 $nodes = $return;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         $nodes = $this->traverseArray($nodes);
Chris@0: 
Chris@0:         foreach ($this->visitors as $visitor) {
Chris@0:             if (null !== $return = $visitor->afterTraverse($nodes)) {
Chris@0:                 $nodes = $return;
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return $nodes;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Recursively traverse a node.
Chris@0:      *
Chris@0:      * @param Node $node Node to traverse.
Chris@0:      *
Chris@0:      * @return Node Result of traversal (may be original node or new one)
Chris@0:      */
Chris@0:     protected function traverseNode(Node $node) : Node {
Chris@0:         foreach ($node->getSubNodeNames() as $name) {
Chris@0:             $subNode =& $node->$name;
Chris@0: 
Chris@0:             if (\is_array($subNode)) {
Chris@0:                 $subNode = $this->traverseArray($subNode);
Chris@0:                 if ($this->stopTraversal) {
Chris@0:                     break;
Chris@0:                 }
Chris@0:             } elseif ($subNode instanceof Node) {
Chris@0:                 $traverseChildren = true;
Chris@4:                 $breakVisitorIndex = null;
Chris@4: 
Chris@4:                 foreach ($this->visitors as $visitorIndex => $visitor) {
Chris@0:                     $return = $visitor->enterNode($subNode);
Chris@0:                     if (null !== $return) {
Chris@0:                         if ($return instanceof Node) {
Chris@0:                             $this->ensureReplacementReasonable($subNode, $return);
Chris@0:                             $subNode = $return;
Chris@0:                         } elseif (self::DONT_TRAVERSE_CHILDREN === $return) {
Chris@0:                             $traverseChildren = false;
Chris@4:                         } elseif (self::DONT_TRAVERSE_CURRENT_AND_CHILDREN === $return) {
Chris@4:                             $traverseChildren = false;
Chris@4:                             $breakVisitorIndex = $visitorIndex;
Chris@4:                             break;
Chris@0:                         } elseif (self::STOP_TRAVERSAL === $return) {
Chris@0:                             $this->stopTraversal = true;
Chris@0:                             break 2;
Chris@0:                         } else {
Chris@0:                             throw new \LogicException(
Chris@0:                                 'enterNode() returned invalid value of type ' . gettype($return)
Chris@0:                             );
Chris@0:                         }
Chris@0:                     }
Chris@0:                 }
Chris@0: 
Chris@0:                 if ($traverseChildren) {
Chris@0:                     $subNode = $this->traverseNode($subNode);
Chris@0:                     if ($this->stopTraversal) {
Chris@0:                         break;
Chris@0:                     }
Chris@0:                 }
Chris@0: 
Chris@4:                 foreach ($this->visitors as $visitorIndex => $visitor) {
Chris@0:                     $return = $visitor->leaveNode($subNode);
Chris@4: 
Chris@0:                     if (null !== $return) {
Chris@0:                         if ($return instanceof Node) {
Chris@0:                             $this->ensureReplacementReasonable($subNode, $return);
Chris@0:                             $subNode = $return;
Chris@0:                         } elseif (self::STOP_TRAVERSAL === $return) {
Chris@0:                             $this->stopTraversal = true;
Chris@0:                             break 2;
Chris@0:                         } elseif (\is_array($return)) {
Chris@0:                             throw new \LogicException(
Chris@0:                                 'leaveNode() may only return an array ' .
Chris@0:                                 'if the parent structure is an array'
Chris@0:                             );
Chris@0:                         } else {
Chris@0:                             throw new \LogicException(
Chris@0:                                 'leaveNode() returned invalid value of type ' . gettype($return)
Chris@0:                             );
Chris@0:                         }
Chris@0:                     }
Chris@4: 
Chris@4:                     if ($breakVisitorIndex === $visitorIndex) {
Chris@4:                         break;
Chris@4:                     }
Chris@0:                 }
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return $node;
Chris@0:     }
Chris@0: 
Chris@0:     /**
Chris@0:      * Recursively traverse array (usually of nodes).
Chris@0:      *
Chris@0:      * @param array $nodes Array to traverse
Chris@0:      *
Chris@0:      * @return array Result of traversal (may be original array or changed one)
Chris@0:      */
Chris@0:     protected function traverseArray(array $nodes) : array {
Chris@0:         $doNodes = [];
Chris@0: 
Chris@0:         foreach ($nodes as $i => &$node) {
Chris@0:             if ($node instanceof Node) {
Chris@0:                 $traverseChildren = true;
Chris@4:                 $breakVisitorIndex = null;
Chris@4: 
Chris@4:                 foreach ($this->visitors as $visitorIndex => $visitor) {
Chris@0:                     $return = $visitor->enterNode($node);
Chris@0:                     if (null !== $return) {
Chris@0:                         if ($return instanceof Node) {
Chris@0:                             $this->ensureReplacementReasonable($node, $return);
Chris@0:                             $node = $return;
Chris@0:                         } elseif (self::DONT_TRAVERSE_CHILDREN === $return) {
Chris@0:                             $traverseChildren = false;
Chris@4:                         } elseif (self::DONT_TRAVERSE_CURRENT_AND_CHILDREN === $return) {
Chris@4:                             $traverseChildren = false;
Chris@4:                             $breakVisitorIndex = $visitorIndex;
Chris@4:                             break;
Chris@0:                         } elseif (self::STOP_TRAVERSAL === $return) {
Chris@0:                             $this->stopTraversal = true;
Chris@0:                             break 2;
Chris@0:                         } else {
Chris@0:                             throw new \LogicException(
Chris@0:                                 'enterNode() returned invalid value of type ' . gettype($return)
Chris@0:                             );
Chris@0:                         }
Chris@0:                     }
Chris@0:                 }
Chris@0: 
Chris@0:                 if ($traverseChildren) {
Chris@0:                     $node = $this->traverseNode($node);
Chris@0:                     if ($this->stopTraversal) {
Chris@0:                         break;
Chris@0:                     }
Chris@0:                 }
Chris@0: 
Chris@4:                 foreach ($this->visitors as $visitorIndex => $visitor) {
Chris@0:                     $return = $visitor->leaveNode($node);
Chris@4: 
Chris@0:                     if (null !== $return) {
Chris@0:                         if ($return instanceof Node) {
Chris@0:                             $this->ensureReplacementReasonable($node, $return);
Chris@0:                             $node = $return;
Chris@0:                         } elseif (\is_array($return)) {
Chris@0:                             $doNodes[] = [$i, $return];
Chris@0:                             break;
Chris@0:                         } elseif (self::REMOVE_NODE === $return) {
Chris@0:                             $doNodes[] = [$i, []];
Chris@0:                             break;
Chris@0:                         } elseif (self::STOP_TRAVERSAL === $return) {
Chris@0:                             $this->stopTraversal = true;
Chris@0:                             break 2;
Chris@0:                         } elseif (false === $return) {
Chris@0:                             throw new \LogicException(
Chris@0:                                 'bool(false) return from leaveNode() no longer supported. ' .
Chris@0:                                 'Return NodeTraverser::REMOVE_NODE instead'
Chris@0:                             );
Chris@0:                         } else {
Chris@0:                             throw new \LogicException(
Chris@0:                                 'leaveNode() returned invalid value of type ' . gettype($return)
Chris@0:                             );
Chris@0:                         }
Chris@0:                     }
Chris@4: 
Chris@4:                     if ($breakVisitorIndex === $visitorIndex) {
Chris@4:                         break;
Chris@4:                     }
Chris@0:                 }
Chris@0:             } elseif (\is_array($node)) {
Chris@0:                 throw new \LogicException('Invalid node structure: Contains nested arrays');
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         if (!empty($doNodes)) {
Chris@0:             while (list($i, $replace) = array_pop($doNodes)) {
Chris@0:                 array_splice($nodes, $i, 1, $replace);
Chris@0:             }
Chris@0:         }
Chris@0: 
Chris@0:         return $nodes;
Chris@0:     }
Chris@0: 
Chris@0:     private function ensureReplacementReasonable($old, $new) {
Chris@0:         if ($old instanceof Node\Stmt && $new instanceof Node\Expr) {
Chris@0:             throw new \LogicException(
Chris@0:                 "Trying to replace statement ({$old->getType()}) " .
Chris@0:                 "with expression ({$new->getType()}). Are you missing a " .
Chris@0:                 "Stmt_Expression wrapper?"
Chris@0:             );
Chris@0:         }
Chris@0: 
Chris@0:         if ($old instanceof Node\Expr && $new instanceof Node\Stmt) {
Chris@0:             throw new \LogicException(
Chris@0:                 "Trying to replace expression ({$old->getType()}) " .
Chris@0:                 "with statement ({$new->getType()})"
Chris@0:             );
Chris@0:         }
Chris@0:     }
Chris@0: }