stackoverflow.com recursively filling multidimensional array

<?php // http://stackoverflow.com/questions/29792309/recursively-database-filling-with-multidimensional-array
//  use functions...

// Now the fun starts...
//
// To make the 'tree walk' useful we shall make it call a 'closure' function
// that has the following signature:
//
// function ($childNode, $parentNode);
//
// 1) The order that it is called in is not determined
// 2) Every node will be visited
//
// It can be used for any processing you wish.

// Helper functions for debugging:
//   showNodeProperties($node);

// -------------------------- Test Data --------------------------
// Need the ROOT to make the 'tree' complete... !important
$root = (object) array(
            'id' => 0,
            'libelle' => 'Root',
            'idTypeCategorie' => null,
            'nomImage' => null,
            'ponderation' => null,
            'fils' => null // supplied data goes here.
       );

// This is actually the  $root->fils property...
$src = array(
         (object) array(
            'id' => 288,
            'libelle' => 'Parent: 0 to here: 288',
            'idTypeCategorie' => 0,
            'nomImage' => '1905.jpg',
            'ponderation' => '1',
            'fils' => array(
                            (object) array(
                                'id' => 2228,
                                'libelle' => 'Parent 288 to here: 2228',
                                'idTypeCategorie' => 1,
                                'nomImage' => '2002.png',
                                'ponderation' => 1,
                                'mea' => 2067,
                                'fils' => array(
                                        (object) array(
                                            'id' => 1024,
                                            'libelle' => 'Parent 2228 to here: 1024',
                                            'idTypeCategorie' => 2,
                                            'nomImage' => null,
                                            'ponderation' => 1,
                                            'nbProduits' => 9,
                                            'fils' =>  Array()
                                        ),
                                        (Object) array(
                                            'id' => 1025,
                                            'libelle' => 'Parent 2228 to here: 1025',
                                            'idTypeCategorie' => 2,
                                            'nomImage' => null,
                                            'ponderation' => 2,
                                            'nbProduits' => 10,
                                            'fils' => Array()
                                        )
                                    ),
                             ),
                             (object) array(
                                'id' => 2229,
                                'libelle' => 'Parent 288 to here: 2229',
                                'idTypeCategorie' => 1,
                                'nomImage' => '2220.png',
                                'ponderation' => 1,
                                'mea' => 2229,
                                'fils' => array(
                                         (Object) array(
                                            'id' => 1036,
                                            'libelle' => 'Parent 2229 to here: 1036',
                                            'idTypeCategorie' => 2,
                                            'nomImage' => null,
                                            'ponderation' => 2,
                                            'nbProduits' => 10,
                                            'fils' => Array()
                                        ),
                                  ),
                            ),
                        ),

             ),
             (object) array(
                'id' => 289,
                'libelle' => 'Parent: 0 to here: 289',
                'idTypeCategorie' => 0,
                'nomImage' => '289.jpg',
                'ponderation' => '1',
                'fils' => array()
             ),
   );

// ---- Closure to be called for every node in the tree ----

// output of the tree walk - The closure MUST USE A REFERENCE to this!
$outWalkedTree = array();

$processNode  = function ($childNode, $parentNode) use (&$outWalkedTree) {

    $curDetails = array();
    $curDetails['parentId'] = $parentNode->id;
    $curDetails['childId'] = $childNode->id;
    $curDetails['libelle'] = $childNode->libelle;

    $outWalkedTree[] = $curDetails;
};
// -------------------------------------------------------------------

// Make the 'complete tree'... it makes the code easier to understand...
$sourceTree = $root;
$sourceTree->fils = $src;

$EOL = '<br />';

echo $EOL, '  -------- Source Tree Start ---------';
echo '<pre>';
print_r($sourceTree);
echo '</pre>';
echo $EOL, '  -------- Source Tree End ---------';


echo $EOL, '  -------- Tree walk Start ---------';
echo $EOL, 'walkTree($sourceTree, null, $processNode);';
walkTree($sourceTree, null, $processNode);
echo $EOL, '  -------- Tree walk  End ---------';

echo $EOL, '  -------- outWalkedTree Start ---------';
echo '<pre>';
print_r($outWalkedTree);
echo '</pre>';
echo $EOL, '  -------- outWalkedTree End ---------';

exit(); // redundant but a clue when reading where the main processing ends

// ------------------- Tree processing functions ------------------------

/**
 * Apply processing to the current node and it's parent node.
 *
 * @param node $currentNode
 * @param node $parentNode
 * @param closure $processNode
 * @return void This is all 'side effects'
 */
function walkTree($currentNode, $parentNode, /* closure */ $processNode)
{
    // call the closure - but only if the parent is set...
    if (is_object($parentNode)) {
        $processNode($currentNode, $parentNode);
    }

    // process the children of this node
    foreach ($currentNode->fils as $childNode) {

        walkTree($childNode, $currentNode, $processNode); // recurse for every node
    }
    return;
}


// ------------------ Helpers -----------------------
function showNodeProperties($node, $title = '')
{
    $EOL = '<br />';
    echo $EOL, '  -------- Node '.  $title .' (id: '. $node->id .') details ---------';
    foreach((array) $node as $property => $value) {

        $propValue = $value;
        if ($property == 'fils') {
             $propValue = 'Child Count: '. count($node->fils);
        }
        echo $EOL, 'Node: key: '. $property .' =>'. $propValue;
    }
    echo $EOL, '  -------- end '.  $title .' (id: '. $node->id .') end ---------';
}