RecursiveTreeIterator that accepts callback for flattening non-string items

RecursiveTreeCallbackIterator.php

<?php

use RecursiveTreeIterator, CachingIterator, RecursiveIterator, RecursiveIteratorIterator;

/**
 * RecursiveTreeIterator that accepts callback for flattening non-string items
 *
 * Class RecursiveTreeCallbackIterator
 */
class RecursiveTreeCallbackIterator extends RecursiveTreeIterator
{
	/**
	 * @var callable
	 */
	private $callback;

	/**
	 * @var int
	 */
	private $rit_flags;

	/**
	 * @param RecursiveIterator $it
	 * @param callable $callback
	 * @param int $rit_flags
	 * @param int $cit_flags
	 * @param int $mode
	 */
	public function __construct(
		RecursiveIterator $it,
		callable $callback,
		$rit_flags = RecursiveTreeIterator::BYPASS_KEY,
		$cit_flags = CachingIterator::CATCH_GET_CHILD,
		$mode = RecursiveIteratorIterator::SELF_FIRST
	) {
		$this->callback = $callback;
		$this->rit_flags = $rit_flags;
		parent::__construct($it, $rit_flags, $cit_flags, $mode);
	}

	/**
	 * @return string
	 */
	function getEntry()
	{
		return @(string)call_user_func($this->callback, RecursiveIteratorIterator::current());
	}

	/**
	 * @return string
	 */
	public function current()
	{
		if ($this->rit_flags & parent::BYPASS_CURRENT)
		{
			return call_user_func($this->callback, RecursiveIteratorIterator::current());
		}
		else
		{
			return $this->getPrefix() . $this->getEntry() .  $this->getPostfix();
		}
	}

}