Question

I have several navigation related functions which I would like to have no depth limits. These generate CSS menus, breadcrumb trails and the like.

I am stumped as to how I would make the functions follow each path to depth or to root without explicit looping.

The following is a typical example where I want the topmost parent of a page. The topmost will have a value of zero in its parent field.

Here is the explicitly looped version:

function topPg() {
    $p = $this->retrieve("id = '$this->parent'");
    if ($p->parent != 0) {
        $gp = $this->retrieve("id = '$p->parent'");
        if ($gp->parent != 0) {
            $ggp = $this->retrieve("id = '$gp->parent'");
            if ($ggp->parent != 0) {
                $gggp = $this->retrieve("id = '$ggp->parent'");
                // ad naseum
            } else {
                return $ggp;
            }
        } else {
            return $gp;
        }
    } else {
        return $p;
    }
} // func

Anyone have advice or similar code or a tute link to help point the way?

Answer 1

It’s easily expressable as a while loop:

$node = $this;
while ($node->parent != 0) {
  $node = $this->retrieve("id = '$node->parent'");
}

$node now contains the topmost element.