Question

Based on Getting a modified preorder tree traversal model (nested set) into a <ul>

One of answers gave right code to display full tree. What i need is to always show first level (depth=0) and siblings+childrens for active list item. Goal is to expand visible part of tree when user selects list item which is parent for more list items.

So, if i got this list:

1. item
2. item
  2.1. item
  2.2. item
    2.2.1. item
    2.2.2. item
    2.2.3. item
  2.3. item
  2.4. item
    2.4.1. item
    2.4.2. item
3. item
4. item
  4.1. item
  4.2. item
    4.2.1. item
    4.2.2. item
5. item

and if current list item is “2.”, list should look like that:

1. item
2. item // this needs class .selected
  2.1. item
  2.2. item
  2.3. item
  2.4. item
3. item
4. item
5. item

and if current list item is “2.2.”, list should look like that:

1. item
2. item // this needs class .selected
  2.1. item
  2.2. item // this needs class .selected
    2.2.1. item
    2.2.2. item
    2.2.3. item
  2.3. item
  2.4. item
3. item
4. item
5. item

Below there is an example code which works well for me to display full tree. I also added lft/rgt/current which will be needed to solve my issue.

<?php
function MyRenderTree ( $tree = array(array('name'=>'','depth'=>'', 'lft'=>'','rgt'=>'')) , $current=false){

   $current_depth = 0;
   $counter = 0;

   $result = '<ul>';

   foreach($tree as $node){
       $node_depth = $node['depth'];
       $node_name = $node['name'];
       $node_id = $node['category_id'];

       if($node_depth == $current_depth){
           if($counter > 0) $result .= '</li>';
       }
       elseif($node_depth > $current_depth){
           $result .= '<ul>';
           $current_depth = $current_depth + ($node_depth - $current_depth);
       }
       elseif($node_depth < $current_depth){
           $result .= str_repeat('</li></ul>',$current_depth - $node_depth).'</li>';
           $current_depth = $current_depth - ($current_depth - $node_depth);
       }
       $result .= '<li id="c'.$node_id.'"';
       $result .= $node_depth < 2 ?' class="open"':'';
       $result .= '><a href="#">'.$node_name.'</a>';
       ++$counter;
   }
   $result .= str_repeat('</li></ul>',$node_depth).'</li>';

   $result .= '</ul>';

   return $result;
}

// "$current" may contain category_id, lft, rgt for active list item
print MyRenderTree($categories,$current);
?>

Answer 1

As you already managed to sort the sequence, why not just output as needed?

As some leafs need to appear closed, so the iterator should be able to skip children of non-selected nodes.

Doing so lead me to an idea to solve the problem of terminating the output tree (output = parsing). What to do if the last valid node in the sequence is at a higher depth than 0? I appended a NULL terminator for that. So still open levels can be closed before the loop finishes.

Additionally the iterator overloads nodes to offer common methods on them, like comparing against the currently selected element.

The MyRenderTree function (Demo/Full code)

Edit: The Demo Codepad has problems, here is the source-code: Gist
Getting nested set model into a but hiding “closed” subtrees

function MyRenderTree($tree = array(array('name'=>'','depth'=>'', 'lft'=>'','rgt'=>'')) , $current=false)
{
    $sequence = new SequenceTreeIterator($tree);

    echo '<ul>';
    $hasChildren = FALSE;
    foreach($sequence as $node)
    {
        if ($close = $sequence->getCloseLevels())
        {
            echo str_repeat('</ul></li>', $close);
            $hasChildren = FALSE;
        }
        if (!$node && $hasChildren)
        {
            echo '</li>', "\n";
        }
        if (!$node) break; # terminator

        $hasChildren = $node->hasChildren();
        $isSelected = $node->isSupersetOf($current);

        $classes = array();
        $isSelected && ($classes[] = 'selected') && $hasChildren && $classes[] = 'open';
        $node->isSame($current) && $classes[] = 'current';

        printf('<li class="%s">%s', implode(' ', $classes), $node['name']);

        if ($hasChildren)
            if ($isSelected)
                echo '<ul>';
            else
                $sequence->skipChildren()
            ;
        else
            echo '</li>'
        ;
    }
    echo '</ul>';
}

This can be solved as well in a single foreach and some variables, however I think for re-useablilty, the implementation based on the SPL Iterators is better.