print dir structure tree - php

<?php

function tree($path, $level = 0, $structure = '', &$onlyOnce = false)
{
    $elements = scandir($path);
    $last = end($elements);
    reset($elements);

    $onlyOnce = true;

    foreach ($elements as $element) {

        if ($element[0] == '.') {
            continue;
        }

        $isLast = $element == $last;
        $currentStructure = $structure . ($isLast ? '`' : '|') . '-- ';

        echo $currentStructure.$element.PHP_EOL;

        $subpath = $path.DIRECTORY_SEPARATOR.$element;

        if (is_dir($subpath)) {
            $sep = $isLast ? '    ' : '|   ';
            tree($subpath, $level+1, $structure.$sep, $onlyOnce);
        }

        if ($isLast && $onlyOnce) {
            echo $structure.PHP_EOL;
            $onlyOnce = false;
        }
    }
}

tree('../..');