php recursive directories render

recursive_directories_render.php

<?php
/**
 * @var $splFileInfo SplFileInfo
 */
$root = '/etc/nginx';
$rdi = new RecursiveDirectoryIterator($root, FilesystemIterator::SKIP_DOTS);
$iterator = new RecursiveIteratorIterator($rdi);
//$iterator =  new RegexIterator($iterator, '/\.txt/', RegexIterator::MATCH);
$tree = [];
foreach ($iterator as $splFileInfo) {
    $fileName = $splFileInfo->getFilename();
    if ($splFileInfo->isLink() === true) {
        $fileName = sprintf('%s -> %s', $fileName, $splFileInfo->getLinkTarget());
    }
    $children = $splFileInfo->isDir() === false ? [$fileName] : [$fileName => []];
    for ($depth = $iterator->getDepth() - 1; $depth >= 0; $depth--) {
        $children = [
            $iterator->getSubIterator($depth)->current()->getFilename() => $children
        ];
    }
    $tree = array_merge_recursive($tree, $children);
}

function sortChildren(&$array)
{
    foreach ($array as &$value) {
        if (is_array($value) === true) {
            sortChildren($value);
        }
    }
    return asort($array);
}

sortChildren($tree);
ksort($tree);

$tree = [
    $root => $tree
];

var_dump($tree);

function renderTree($tree, $depth = 0) {
    $output = '';
    foreach ($tree as $parent => $children) {
        if (is_string($parent) === true) {
            $output .= '|';
            $output .= str_repeat('-', $depth * 2);
            $output .= '/';
            $output .= ltrim($parent, '/');
            $output .= PHP_EOL;
            $output .= renderTree($children, $depth + 1);
        } else {
            $output .= '|';
            $output .= str_repeat('-', $depth * 2);
            $output .= $children;
            $output .= PHP_EOL;
        }
    }
    return $output;
}

printf('<pre>%s</pre>', renderTree($tree));