gistfile1.php

<?php

/**
 * Build Directory array
 */
function loopDir($path = null) {
    if($path === null) {
        $path = './';
    }
     
    $d = dir($path);
    $arr = array();
    while(false !== ($f = $d->read())) {
        if ($f === "." || $f === "..") {
            continue;
        }

        $node = array();
        $node['type'] = 'Text';
        $node['label'] = $f;
        if(is_dir($d->path . $f . '/')) {
            $node['type'] = 'MenuNode';
            $node['children'] = loopDir($d->path . $f . '/');
        }
        array_push($arr,$node);
    }
    return $arr;
}

/**
 * Custom Sort function for nodes
 */
function labelComp($a,$b) {
    return strcmp($a["label"], $b["label"]);
}

/**
 * Sort the directory based on labels
 * Sort children recursively
 */
function sortDirectory($arr) {
    usort($arr,'labelComp');

    foreach($arr as $k => $node) {
        if($node['type'] === 'MenuNode') {
            $arr[$k]['children'] = sortDirectory($node['children']);
        }
    }

    return $arr;
}

/**
 * Sample use; converts to json string
 */
print_r(json_encode(sortDirectory(loopDir('../urls/'))));