Tree

Tree is a class that models a hierarchy of data items (nodes) using a parent/child relationship (tree). Each data item can have only one parent, but a parent can have any number of children. There can only be one root item.

Initialization

The library should be initialized with an array of arrays, using the init method. Each of the latter represents a node. It must contain an id (integer), a value (string) and a parent ID (integer). The parent id can be NULL to indicate the root item. Once initialized the data is read-only.

Example

The following example creates a tree with 4 nodes. Node 1 is the parent node.

$tree = new Tree();
$tree->init([
    ['id' => 2, 'parent_id' => 1, 'value' => 'David- child 1'],
    ['id' => 1, 'parent_id' => null, 'value' => 'Grandfather- root'],
    ['id' => 3, 'parent_id' => 1, 'value' => 'Sharon- child 2'],
    ['id' => 4, 'parent_id' => 2, 'value' => 'grandchild']
]);

Methods Available

getRoot Returns the id of the root node of the tree.

getValue Returns the value of the specified node.

getChildren Returns an array of the ids of all the child nodes of the specified node.

By Mark Stern (markalexstern@gmail.com)