Add method to get depth of tree's node.

Backported from 3.0.

lib/Cake/Model/Behavior/TreeBehavior.php

@@ -996,6 +996,41 @@ public function verify(Model $Model) {
 		return true;
 	}
 
+/**
+ * Returns the depth level of a node in the tree.
+ *
+ * @param Model $Model Model using this behavior
+ * @param int|string $id The primary key for record to get the level of.
+ * @return int|bool Integer of the level or false if the node does not exist.
+ */
+	public function getLevel(Model $Model, $id = null) {
+		if ($id === null) {
+			$id = $Model->id;
+		}
+
+		$node = $Model->find('first', array(
+			'conditions' => array($Model->escapeField() => $id),
+			'order' => false,
+			'recursive' => -1
+		));
+
+		if (empty($node)) {
+			return false;
+		}
+
+		extract($this->settings[$Model->alias]);
+
+		return $Model->find('count', array(
+			'conditions' => array(
+				$scope,
+				$left . ' <' => $node[$Model->alias][$left],
+				$right . ' >' => $node[$Model->alias][$right]
+			),
+			'order' => false,
+			'recursive' => -1
+		));
+	}
+
 /**
  * Sets the parent of the given node
  *

lib/Cake/Test/Case/Model/Behavior/TreeBehaviorNumberTest.php

@@ -548,6 +548,26 @@ public function testMovePromote() {
 		$this->assertTrue($validTree);
 	}
 
+/**
+ * testGetLevel method
+ *
+ * @return void
+ */
+	public function testGetLevel() {
+		extract($this->settings);
+		$this->Tree = new $modelClass();
+		$this->Tree->initialize(2, 2);
+		$this->Tree->id = null;
+
+		$result = $this->Tree->getLevel(5);
+		$this->assertEquals(1, $result);
+
+		$result = $this->Tree->getLevel(3);
+		$this->assertEquals(2, $result);
+
+		$this->assertFalse($this->Tree->getLevel(999));
+	}
+
 /**
  * testMoveWithWhitelist method
  *