gistfile1.php

<?php
/**
 *
 * All nodes should be added from a list
 * where the nodes are ordered by parent then id
 *
 * MikeC - My favourite object
 */
class Gravitywell_Tree
{
    
    /**
     *  
     * this node's id
     */
    public $id;
    
    /**
     * 
     * parent id
     */
    public $parent;
    
    /**
     * 
     * array of hops
     */
    public $hops;
    
    /**
     * 
     * This object's data
     */
    public $data = null;
    
    /**
     * 
     * Object Reference
     */
    protected $_arrRefs = array();
    
    /**
     * 
     * Child nodes
     */
    protected $_childNodes = array();

    
    /**
     *
     * Construct
     */
    public function __construct($id = 0, $parent = 0)
    {
        $this->id = $id;
        $this->parent = $parent;
        $this->_arrRefs[$id] = &$this;
        
        // Add the root hop
        $this->hops = array(0 => $id);
    }
    
    
    /**
     * Add a child to a parent
     *
     */
    public function addChild($parent, $id, $data = null)
    {
        if($obj = $this->findParent($parent)) {
        
            // Rerun this class for the child
            $newObj = new self($id, $parent);
            
            // do hops
            $newObj->hops          = $obj->hops;
            $newObj->hops[]        = $id;
            
            // add data
            $newObj->data          = $data;
            
            // Add our child node
            $obj->_childNodes[$id] = $newObj;
            
            // Create the reference to it
            $this->_arrRefs[$id]   = &$newObj;  
        }
        else {
            // Could not find the parent
            throw new Exception('Gravitywell_Tree::addChild: Unknown parent id');
        }
    }
    
    /**
     * hasChildren
     *
     * does this obj node have children
     */
    public function hasChildren()
    {
        return (bool) count($this->_childNodes);
    }
    
    /**
     * function getChildren
     * @param $obj
     * @return array of Gravitywell_Tree objects
     */
    public function getChildren($obj = null) {
        
        if (!$obj) {
            $obj = $this;
        }
        
        if (!$obj->hasChildren()) {
            return false;
        }
        
        return $obj->_childNodes;
    }
    
    /**
     *  return the array of hops from here to root node 
     */
    public function getHops()
    {
        return $this->hops;
    }
    
     /**
     * findNode
     *
     * @param int $id
     * @return object this|false
     */
    public function findNode($id)
    {
        return $this->findParent($id);
    }
    
     /**
     * findChild
     *
     * @param int $id
     * @return object this|false
     **/
    public function findChild($id)
    {
        return $this->findParent($id);
    }
    
    
    /**
     * FindParent
     *
     * Finds the parent for a child/parent/node who cares?
     *
     * @param int $id
     * @return object this|false
     */
    public function findParent($id)
    {
        if(isset ($this->_arrRefs[$id])) {
            return $this->_arrRefs[$id];
        } else {
            return false;
        }
    }
    
    /**
     * 
     * set this nodes data property
     */
    public function setData($data)
    {
        $this->data = $data;    
    }
    
    /**
     * 
     * returns the nodes data property
     */
    public function getData()
    {
        return $this->data;    
    }
}