Add ability to move subtree to root (#11)

Author: kimpepper

src/NestedSetInterface.php

@@ -132,6 +132,14 @@ public function findParent(Node $node);
    */
   public function getNode($id, $revision_id);
 
+  /**
+   * Moves a subtree to be a new root of the tree.
+   *
+   * @param \PNX\NestedSet\Node $node
+   *   The node to become the new root node.
+   */
+  public function moveSubTreeToRoot(Node $node);
+
   /**
    * Moves a node and its sub-tree below the target node.
    *

src/Storage/DbalNestedSet.php

@@ -15,10 +15,7 @@ class DbalNestedSet extends BaseDbalStorage implements NestedSetInterface {
    * {@inheritdoc}
    */
   public function addRootNode(Node $node) {
-    $maxRight = $this->connection->fetchColumn('SELECT MAX(right_pos) FROM ' . $this->tableName);
-    if ($maxRight === FALSE) {
-      $maxRight = 0;
-    }
+    $maxRight = $this->findMaxRightPosition();
     return $this->doInsertNode($node->getId(), $node->getRevisionId(), $maxRight + 1, $maxRight + 2, 0);
   }
 
@@ -305,6 +302,14 @@ public function deleteSubTree(Node $node) {
 
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function moveSubTreeToRoot(Node $node) {
+    $root = $this->findRoot($node);
+    $this->moveSubTreeBefore($root, $node);
+  }
+
   /**
    * {@inheritdoc}
    */
@@ -401,4 +406,18 @@ public function getNodeAtPosition($left) {
     }
   }
 
+  /**
+   * Finds the maximum right position of the tree.
+   *
+   * @return int
+   *   The max right position.
+   */
+  protected function findMaxRightPosition() {
+    $maxRight = $this->connection->fetchColumn('SELECT MAX(right_pos) FROM ' . $this->tableName);
+    if ($maxRight === FALSE) {
+      $maxRight = 0;
+    }
+    return $maxRight;
+  }
+
 }

tests/Functional/DbalNestedSetTest.php

@@ -346,6 +346,29 @@ public function testMoveSubTreeBelow() {
 
   }
 
+  /**
+   * Tests moving a sub-tree to the root.
+   */
+  public function testMoveSubTreeToRoot() {
+
+    $node = $this->nestedSet->getNode(7, 1);
+
+    $this->nestedSet->moveSubTreeToRoot($node);
+
+    // Assert we are at the root now.
+    $newRoot = $this->nestedSet->getNode(7, 1);
+    $this->assertEquals(1, $newRoot->getLeft());
+    $this->assertEquals(6, $newRoot->getRight());
+    $this->assertEquals(0, $newRoot->getDepth());
+
+    // Assert old root has had left and right updated.
+    $oldRoot = $this->nestedSet->getNode(1, 1);
+    $this->assertEquals(7, $oldRoot->getLeft());
+    $this->assertEquals(22, $oldRoot->getRight());
+    $this->assertEquals(0, $oldRoot->getDepth());
+
+  }
+
   /**
    * Tests moving a sub-tree before a target node.
    */