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