gistfile1.txt

static public function relativise($path, $workingpath = null) {
    if(is_null($workingpath)) $workingpath = self::CorrectPathSlashes(getcwd());
    $path = preg_replace('#([^/]+/\.\.)#', '', $path);
    $path = preg_replace('#(\./|/\.$)#', '', $path);
    $path = preg_replace('#/{2,}#', '/', $path);
    $path = preg_replace('#/$#', '', $path);

    $workingpath = preg_replace('#([^/]+/\.\.)#', '', $workingpath);
    $workingpath = preg_replace('#(\./|/\.$)#', '', $workingpath);
    $workingpath = preg_replace('#/{2,}#', '/', $workingpath);
    $workingpath = preg_replace('#/$#', '', $workingpath);


    $path = explode('/', $path);
    if($path[0] !== '') {
        return implode('/', $path);
    } else {
        $workingpath = explode('/', $workingpath);
        $i=count($workingpath);
        $relativepath = array();
        $wp = array_combine(array_reverse(array_keys($workingpath)), array_reverse($workingpath));
        foreach($wp as $n=>$part){
            if(!isset($path[$n]) || $path[$n]!=$part) {$relativepath[] = '..'; $i = $n;}
        }
        $relativepath = array_reverse($relativepath);
        for($c=count($path), $end=false; $i < $c && !$end; $i++) {
            $relativepath[] = $path[$i];
        }
        $relativepath = implode('/', $relativepath);
    }

    return $relativepath;
}