--- /dev/null
+Frequently Asked Questions
+==========================
+
+ * [How can the parent of a node be obtained?](#how-can-the-parent-of-a-node-be-obtained)
+ * [How can the next/previous sibling of a node be obtained?](#how-can-the-nextprevious-sibling-of-a-node-be-obtained)
+
+How can the parent of a node be obtained?
+-----
+
+The AST does not store parent nodes by default. However, it is easy to add a custom parent node
+attribute using a custom node visitor:
+
+```php
+use PhpParser\Node;
+use PhpParser\NodeVisitorAbstract;
+
+class ParentConnector extends NodeVisitorAbstract {
+ private $stack;
+ public function beforeTraverse(array $nodes) {
+ $this->stack = [];
+ }
+ public function enterNode(Node $node) {
+ if (!empty($this->stack)) {
+ $node->setAttribute('parent', $this->stack[count($this->stack)-1]);
+ }
+ $this->stack[] = $node;
+ }
+ public function leaveNode(Node $node) {
+ array_pop($this->stack);
+ }
+}
+```
+
+After running this visitor, the parent node can be obtained through `$node->getAttribute('parent')`.
+
+How can the next/previous sibling of a node be obtained?
+-----
+
+Again, siblings are not stored by default, but the visitor from the previous entry can be easily
+extended to store the previous / next node with a common parent as well:
+
+```php
+use PhpParser\Node;
+use PhpParser\NodeVisitorAbstract;
+
+class NodeConnector extends NodeVisitorAbstract {
+ private $stack;
+ private $prev;
+ public function beforeTraverse(array $nodes) {
+ $this->stack = [];
+ $this->prev = null;
+ }
+ public function enterNode(Node $node) {
+ if (!empty($this->stack)) {
+ $node->setAttribute('parent', $this->stack[count($this->stack)-1]);
+ }
+ if ($this->prev && $this->prev->getAttribute('parent') == $node->getAttribute('parent')) {
+ $node->setAttribute('prev', $this->prev);
+ $this->prev->setAttribute('next', $node);
+ }
+ $this->stack[] = $node;
+ }
+ public function leaveNode(Node $node) {
+ $this->prev = $node;
+ array_pop($this->stack);
+ }
+}
+```