Traversing a Graph using depth first search in PHP

DepthFirstSearch.php

<?php
/**
 * Created by PhpStorm.
 * User: adriano
 * Date: 09/11/19
 * Time: 13:18
 */

class Node {

	private $data;
	private $visited = false;
	private $edges = [];

	public function __construct( $data ) {
		$this->data = $data;
	}

	public function getData() {
		return $this->data;
	}

	public function getEdges(): array {
		return $this->edges;
	}

	public function setEdges( array $edges ) {
		$this->edges = $edges;
	}

	public function markVisited() {
		$this->visited = true;
	}

	public function isVisited() {
		 return $this->visited;
	}
}

class Graph {

	private $nodes;

	public function __construct( $nodes ) {
		$this->nodes = $nodes;
	}

	public function getNodes() {
		return $this->nodes;
	}

	public function traverseDFS(): void {
		$stack = [ current( $this->nodes ) ];
		$currentVertex = current( $stack );
		$currentVertex->markVisited();

		echo 'Visited:' . $currentVertex->getData() . PHP_EOL;

		while( $stack ) {
			$visitedEdges = 0;
			foreach( $currentVertex->getEdges() as $edge ) {
				if ( $edge->isVisited() ) {
					$visitedEdges++;
					continue;
				}

				$edge->markVisited();
				echo 'Visited:' . $edge->getData() . PHP_EOL;
				$stack[] = $edge;
				$currentVertex = $edge;
				break;
			}

			if ( ! $currentVertex->getEdges() || $visitedEdges === count( $currentVertex->getEdges() ) ) {
				array_pop( $stack );
				end( $stack );
				$currentVertex = current( $stack );
			}
		}
	}
}


$a = new Node( 'A' );
$b = new Node( 'B' );
$c = new Node( 'C' );
$d = new Node( 'D' );
$e = new Node( 'E' );
$f = new Node( 'F' );

$a->setEdges( [ $b, $c ] );
$b->setEdges( [ $d ] );
$d->setEdges( [ $e, $f ] );

$graph = new Graph( [ $a, $b, $c, $d, $e, $f ] );
$graph->traverseDFS();
$test = 1;