NodeWalker.php
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<?php
declare(strict_types=1);
/*
* This file is part of the league/commonmark package.
*
* (c) Colin O'Dell <colinodell@gmail.com>
*
* Original code based on the CommonMark JS reference parser (https://bitly.com/commonmark-js)
* - (c) John MacFarlane
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace League\CommonMark\Node;
use League\CommonMark\Node\Block\AbstractBlock;
final class NodeWalker
{
/** @psalm-readonly */
private Node $root;
/** @psalm-readonly-allow-private-mutation */
private ?Node $current = null;
/** @psalm-readonly-allow-private-mutation */
private bool $entering;
public function __construct(Node $root)
{
$this->root = $root;
$this->current = $this->root;
$this->entering = true;
}
/**
* Returns an event which contains node and entering flag
* (entering is true when we enter a Node from a parent or sibling,
* and false when we reenter it from child)
*/
public function next(): ?NodeWalkerEvent
{
$current = $this->current;
$entering = $this->entering;
if ($current === null) {
return null;
}
if ($entering && ($current instanceof AbstractBlock || $current->hasChildren())) {
if ($current->firstChild()) {
$this->current = $current->firstChild();
$this->entering = true;
} else {
$this->entering = false;
}
} elseif ($current === $this->root) {
$this->current = null;
} elseif ($current->next() === null) {
$this->current = $current->parent();
$this->entering = false;
} else {
$this->current = $current->next();
$this->entering = true;
}
return new NodeWalkerEvent($current, $entering);
}
/**
* Resets the iterator to resume at the specified node
*/
public function resumeAt(Node $node, bool $entering = true): void
{
$this->current = $node;
$this->entering = $entering;
}
}