lib: Add SimpleTree

Simple tree implementation for TreeNodes.

refs #6630

library/Icinga/Data/Tree/SimpleTree.php

@@ -0,0 +1,90 @@
+<?php
+/* Icinga Web 2 | (c) 2013-2015 Icinga Development Team | GPLv2+ */
+
+namespace Icinga\Data\Tree;
+
+use IteratorAggregate;
+use LogicException;
+
+/**
+ * A simple tree
+ */
+class SimpleTree implements IteratorAggregate
+{
+    /**
+     * Root node
+     *
+     * @type TreeNode
+     */
+    protected $sentinel;
+
+    /**
+     * Nodes
+     *
+     * @type array
+     */
+    protected $nodes = array();
+
+    /**
+     * Create a new simple tree
+     */
+    public function __construct()
+    {
+        $this->sentinel = new TreeNode();
+    }
+
+    /**
+     * Add a child node
+     *
+     * @param   TreeNode $child
+     * @param   TreeNode $parent
+     *
+     * @return $this
+     */
+    public function addChild(TreeNode $child, TreeNode $parent = null)
+    {
+        if ($parent === null) {
+            $parent = $this->sentinel;
+        } elseif (! isset($this->nodes[$parent->getId()])) {
+            throw new LogicException(sprintf(
+                'Can\'t append child node %s to parent node %s: Parent node does not exist',
+                $child->getId(),
+                $parent->getId()
+            ));
+        }
+        if (isset($this->nodes[$child->getId()])) {
+            throw new LogicException(sprintf(
+                'Can\'t append child node %s to parent node %s: Child node does already exist',
+                $child->getId(),
+                $parent->getId()
+            ));
+        }
+        $this->nodes[$child->getId()] = $child;
+        $parent->appendChild($child);
+        return $this;
+    }
+
+    /**
+     * Get a node by its ID
+     *
+     * @param   mixed   $id
+     *
+     * @return  TreeNode|null
+     */
+    public function getNode($id)
+    {
+        if (! isset($this->nodes[$id])) {
+            return null;
+        }
+        return $this->nodes[$id];
+    }
+
+    /**
+     * {@inheritdoc}
+     * @return TreeNodeIterator
+     */
+    public function getIterator()
+    {
+        return new TreeNodeIterator($this->sentinel);
+    }
+}