<?php
/*
* This file is part of the league/commonmark package.
*
* (c) Colin O'Dell <[email protected]>
*
* 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;
final class NodeWalker
{
/**
* @var Node
*/
private $root;
/**
* @var Node|null
*/
private $current;
/**
* @var bool
*/
private $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)
*
* @return NodeWalkerEvent|null
*/
public function next(): ?NodeWalkerEvent
{
$current = $this->current;
$entering = $this->entering;
if (null === $current) {
return null;
}
if ($entering && $current->isContainer()) {
if ($current->firstChild()) {
$this->current = $current->firstChild();
$this->entering = true;
} else {
$this->entering = false;
}
} elseif ($current === $this->root) {
$this->current = null;
} elseif (null === $current->next()) {
$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
*
* @param Node $node
* @param bool $entering
*
* @return void
*/
public function resumeAt(Node $node, bool $entering = true)
{
$this->current = $node;
$this->entering = $entering;
}
}