Use classes for visitors

lib/PHPParser/NodeTraverser.php

@@ -2,83 +2,61 @@
 
 class PHPParser_NodeTraverser
 {
-    const ON_ENTER = 1;
-    const ON_LEAVE = 2;
-
-    protected $enterVisitors;
-    protected $leaveVisitors;
+    /**
+     * @var PHPParser_NodeVisitorInterface[] Visitors
+     */
+    protected $visitors;
 
     /**
      * Constructs a node traverser.
      */
     public function __construct() {
-        $this->enterVisitors = $this->leaveVisitors = array();
+        $this->visitors = array();
     }
 
     /**
-     * Adds a node visitor.
+     * Adds a visitor.
      *
-     * The callback gets the node passed as only argument and may return a replacement for the node
-     * or return null/nothing, in which case the node is left untouched.
-     *
-     * The mode specifies when the node should be visited:
-     *  * using self::ON_ENTER the node is visited before traversing its sub nodes
-     *  * using self::ON_LEAVE the node is visited after traversing its sub nodes
-     *  * using self::ON_ENTER | self::ON_LEAVE the node is visited both before and after traversing
-     *    its subnodes
-     * The default is to visit the node ON_ENTER.
-     *
-     * Visitors are called in the order they were registered in.
-     *
-     * @param callback $visitor Visitor callback
-     * @param int      $mode    Visitor mode (bitmap using self::ON_ENTER and self::ON_LEAVE)
-     *
-     * @throws InvalidArgumentException if visitor is not callable
+     * @param PHPParser_NodeVisitorInterface $visitor Visitor to add
      */
-    public function addVisitor($visitor, $mode = self::ON_ENTER) {
-        if (!is_callable($visitor)) {
-            throw new InvalidArgumentException('Visitor not callable');
-        }
-
-        if ($mode & self::ON_ENTER) {
-            $this->enterVisitors[] = $visitor;
-        }
-
-        if ($mode & self::ON_LEAVE) {
-            $this->leaveVisitors[] = $visitor;
-        }
+    public function addVisitor(PHPParser_NodeVisitorInterface $visitor) {
+        $this->visitors[] = $visitor;
     }
 
     /**
      * Traverses a node or an array using the registered visitors.
      *
      * @param PHPParser_NodeAbstract|array $node Node or array
-     *
-     * @return mixed Node after all visitors were applied.
      */
-    public function traverse($node) {
+    public function traverse(&$node) {
+        foreach ($this->visitors as $visitor) {
+            $visitor->beforeTraverse($node);
+        }
+
+        $this->_traverse($node);
+
+        foreach ($this->visitors as $visitor) {
+            $visitor->afterTraverse($node);
+        }
+    }
+
+    protected function _traverse(&$node) {
         if ($node instanceof PHPParser_NodeAbstract) {
-            foreach ($this->enterVisitors as $visitor) {
-                if (null !== $return = call_user_func($visitor, $node)) {
-                    $node = $return;
-                }
+            foreach ($this->visitors as $visitor) {
+                $visitor->enterNode($node);
             }
         }
 
         if (is_array($node) || $node instanceof Traversable) {
             foreach ($node as &$subNode) {
-                $subNode = $this->traverse($subNode);
+                $this->_traverse($subNode);
             }
         }
 
         if ($node instanceof PHPParser_NodeAbstract) {
-            foreach ($this->leaveVisitors as $visitor) {
-                if (null !== $return = call_user_func($visitor, $node)) {
-                    $node = $return;
-                }
+            foreach ($this->visitors as $visitor) {
+                $visitor->leaveNode($node);
             }
         }
-
-        return $node;
     }
 }

lib/PHPParser/NodeVisitorAbstract.php

@@ -0,0 +1,9 @@
+<?php
+
+class PHPParser_NodeVisitorAbstract implements PHPParser_NodeVisitorInterface
+{
+    public function beforeTraverse(&$node) { }
+    public function enterNode(PHPParser_NodeAbstract &$node) { }
+    public function leaveNode(PHPParser_NodeAbstract &$node) { }
+    public function afterTraverse(&$node) { }
+}

lib/PHPParser/NodeVisitorInterface.php

@@ -0,0 +1,32 @@
+<?php
+
+interface PHPParser_NodeVisitorInterface
+{
+    /**
+     * Called once before traversal.
+     *
+     * @param $node
+     */
+    public function beforeTraverse(&$node);
+
+    /**
+     * Called when entering a node.
+     *
+     * @param PHPParser_NodeAbstract $node
+     */
+    public function enterNode(PHPParser_NodeAbstract &$node);
+
+    /**
+     * Called when leaving a node.
+     *
+     * @param PHPParser_NodeAbstract $node
+     */
+    public function leaveNode(PHPParser_NodeAbstract &$node);
+
+    /**
+     * Called once after traversal.
+     *
+     * @param $node
+     */
+    public function afterTraverse(&$node);
+}