lib: Add NodeInterface

library/Icinga/Data/Tree/NodeInterface.php

@@ -0,0 +1,38 @@
+<?php
+// {{{ICINGA_LICENSE_HEADER}}}
+// {{{ICINGA_LICENSE_HEADER}}}
+
+namespace Icinga\Data\Tree;
+
+interface NodeInterface
+{
+    /**
+     * Append a child to the node
+     *
+     * @param   mixed $value
+     *
+     * @return  self
+     */
+    public function appendChild($value);
+
+    /**
+     * Get the node's value
+     *
+     * @return mixed
+     */
+    public function getValue();
+
+    /**
+     * Whether the node has children
+     *
+     * @return bool
+     */
+    public function hasChildren();
+
+    /**
+     * Get the node's children
+     *
+     * @return array
+     */
+    public function getChildren();
+}