Mercurial > hg > isophonics-drupal-site
view vendor/nikic/php-parser/doc/component/FAQ.markdown @ 17:129ea1e6d783
Update, including to Drupal core 8.6.10
author | Chris Cannam |
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date | Thu, 28 Feb 2019 13:21:36 +0000 |
parents | 5fb285c0d0e3 |
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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); } } ```