Adds findParent method

Author: kimpepper

src/NestedSetInterface.php

@@ -71,6 +71,17 @@ public function findChildren(Node $node);
    */
   public function findAncestors(Node $node);
 
+  /**
+   * Finds the parent node.
+   *
+   * @param \PNX\NestedSet\Node $node
+   *   The node.
+   *
+   * @return Node
+   *   The parent node.
+   */
+  public function findParent(Node $node);
+
   /**
    * Gets a node for the ID and Revision ID.
    *

src/Storage/DbalNestedSet.php

@@ -152,6 +152,18 @@ public function findAncestors(Node $node) {
     return $ancestors;
   }
 
+  /**
+   * {@inheritdoc}
+   */
+  public function findParent(Node $node) {
+    $ancestors = $this->findAncestors($node);
+    if (count($ancestors) > 1) {
+      // Parent is 2nd-last element.
+      return $ancestors[count($ancestors) - 2];
+    }
+    return NULL;
+  }
+
   /**
    * {@inheritdoc}
    */

tests/Functional/DbalNestedSetTest.php

@@ -143,6 +143,22 @@ public function testFindAncestors() {
 
   }
 
+  /**
+   * Tests finding the parent node.
+   */
+  public function testFindParent() {
+
+    $node = $this->nestedSet->getNode(7, 1);
+
+    $parent = $this->nestedSet->findParent($node);
+
+    $this->assertEquals(3, $parent->getId());
+    $this->assertEquals(1, $parent->getRevisionId());
+    $this->assertEquals(10, $parent->getLeft());
+    $this->assertEquals(21, $parent->getRight());
+
+  }
+
   /**
    * Tests adding a node.
    */