$node stays as-is * * array (of Nodes) * => The return value is merged into the parent array (at the position of the $node) * * NodeTraverser::REMOVE_NODE * => $node is removed from the parent array * * NodeTraverser::DONT_TRAVERSE_CHILDREN * => Children of $node are not traversed. $node stays as-is * * NodeTraverser::DONT_TRAVERSE_CURRENT_AND_CHILDREN * => Further visitors for the current node are skipped, and its children 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 Node|Node[]|NodeTraverser::*|null Replacement node (or special return value) */ 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 Node|Node[]|NodeTraverser::REMOVE_NODE|NodeTraverser::STOP_TRAVERSAL|null Replacement node (or special return value) */ 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 Node[]|null Array of nodes */ public function afterTraverse(array $nodes): ?array; }