Help with Reverse Tree Traversal using Recursion ..

[Greg Schnippel <schnippy@xxxxxxxxx>]

I have a large data tree that I wanted to display in an outline
format. I used a textbook tree recursion function to go through the
data and display it as nested unordered lists:

function outputTree($id) {

       if (checkChildObjectExists($id)) {
               print "<ul>";
               $child = getChildArray($id);
               foreach ($child as $key => $value) {
                       print "<li><a href=\"/object/$key/\">$value</a></li>";
                       outputTree($key);
               }
               print "</ul>";
       }
}

This works as expected:

> Level 1 (Top)
   > Level 2
      > Level 3 (Bottom)

However, I also want to display a reverse tree to allow users to trace
their way back up the tree after landing on a lower branch. I tried to
be clever and reverse the function above as:

function outputReverseTree($id) {

       if (checkParentExists($id)) {
               print "<ul>";
               $parent = getParentArray($id);
               foreach ($parent as $key => $value) {
                       print "<li><a href=\"/object/$key/\">$value</a>\n";
                       outputReverseTree($key);
               }
               print "</ul>";
       }
}

Which works, but there is something wrong with my logic as the tree
comes back reversed:

> Level 3 (Bottom)
   > Level 2
      > Level 1 (Top)

Any suggestions on how to do this?

Thanks,

- Greg

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