--- /dev/null
+<?php
+
+namespace PhpParser;
+
+interface NodeVisitor
+{
+ /**
+ * Called once before traversal.
+ *
+ * Return value semantics:
+ * * null: $nodes stays as-is
+ * * otherwise: $nodes is set to the return value
+ *
+ * @param Node[] $nodes Array of nodes
+ *
+ * @return null|Node[] Array of nodes
+ */
+ public function beforeTraverse(array $nodes);
+
+ /**
+ * Called when entering a node.
+ *
+ * Return value semantics:
+ * * null
+ * => $node stays as-is
+ * * NodeTraverser::DONT_TRAVERSE_CHILDREN
+ * => Children of $node are not traversed. $node stays as-is
+ * * NodeTraverser::STOP_TRAVERSAL
+ * => Traversal is aborted. $node stays as-is
+ * * otherwise
+ * => $node is set to the return value
+ *
+ * @param Node $node Node
+ *
+ * @return null|int|Node Node
+ */
+ public function enterNode(Node $node);
+
+ /**
+ * Called when leaving a node.
+ *
+ * Return value semantics:
+ * * null
+ * => $node stays as-is
+ * * NodeTraverser::REMOVE_NODE
+ * => $node is removed from the parent array
+ * * NodeTraverser::STOP_TRAVERSAL
+ * => Traversal is aborted. $node stays as-is
+ * * array (of Nodes)
+ * => The return value is merged into the parent array (at the position of the $node)
+ * * otherwise
+ * => $node is set to the return value
+ *
+ * @param Node $node Node
+ *
+ * @return null|false|int|Node|Node[] Node
+ */
+ public function leaveNode(Node $node);
+
+ /**
+ * Called once after traversal.
+ *
+ * Return value semantics:
+ * * null: $nodes stays as-is
+ * * otherwise: $nodes is set to the return value
+ *
+ * @param Node[] $nodes Array of nodes
+ *
+ * @return null|Node[] Array of nodes
+ */
+ public function afterTraverse(array $nodes);
+}
\ No newline at end of file