From 05866ac5178ccb4c48059b58290e259b2b9ac53b Mon Sep 17 00:00:00 2001
From: Aleksi Hietanen <aleksi@vaadin.com>
Date: Thu, 18 May 2017 15:24:45 +0300
Subject: Add TreeData#addRootItems, getRootItems

---
 server/src/main/java/com/vaadin/data/TreeData.java | 63 ++++++++++++++++++++++
 .../vaadin/data/provider/TreeDataProviderTest.java | 17 ++++++
 2 files changed, 80 insertions(+)

diff --git a/server/src/main/java/com/vaadin/data/TreeData.java b/server/src/main/java/com/vaadin/data/TreeData.java
index 2311a71984..7f6cc095bc 100644
--- a/server/src/main/java/com/vaadin/data/TreeData.java
+++ b/server/src/main/java/com/vaadin/data/TreeData.java
@@ -96,6 +96,60 @@ public class TreeData<T> implements Serializable {
         itemToWrapperMap.put(null, new HierarchyWrapper<>(null, null));
     }
 
+    /**
+     * Adds the items as root items to this structure.
+     *
+     * @param items
+     *            the items to add
+     * @return this
+     *
+     * @throws IllegalArgumentException
+     *             if any of the given items have already been added to this
+     *             structure
+     * @throws NullPointerException
+     *             if any of the items are {code null}
+     */
+    public TreeData<T> addRootItems(T... items) {
+        addItems(null, items);
+        return this;
+    }
+
+    /**
+     * Adds the items of the given collection as root items to this structure.
+     *
+     * @param items
+     *            the collection of items to add
+     * @return this
+     *
+     * @throws IllegalArgumentException
+     *             if any of the given items have already been added to this
+     *             structure
+     * @throws NullPointerException
+     *             if any of the items are {code null}
+     */
+    public TreeData<T> addRootItems(Collection<T> items) {
+        addItems(null, items);
+        return this;
+    }
+
+    /**
+     * Adds the items of the given stream as root items to this structure.
+     *
+     * @param items
+     *            the stream of root items to add
+     * @return this
+     *
+     * @throws IllegalArgumentException
+     *             if any of the given items have already been added to this
+     *             structure
+     * @throws NullPointerException
+     *             if any of the items are {code null}
+     */
+    public TreeData<T> addRootItems(Stream<T> items) {
+        addItems(null, items);
+        return this;
+    }
+
     /**
      * Adds a data item as a child of {@code parent}. Call with {@code null} as
      * parent to add a root level item. The given parent item must already exist
@@ -283,6 +337,15 @@ public class TreeData<T> implements Serializable {
         return this;
     }
 
+    /**
+     * Gets the root items of this structure.
+     *
+     * @return the root items of this structure
+     */
+    public List<T> getRootItems() {
+        return getChildren(null);
+    }
+
     /**
      * Get the immediate child items for the given item.
      *
diff --git a/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java b/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java
index f0b2d5f81f..186ed14e8a 100644
--- a/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java
+++ b/server/src/test/java/com/vaadin/data/provider/TreeDataProviderTest.java
@@ -80,6 +80,23 @@ public class TreeDataProviderTest
         Assert.assertTrue(data.getChildren(null).contains(item));
     }
 
+    @Test
+    public void treeData_root_items() {
+        TreeData<String> data = new TreeData<>();
+        TreeData<String> dataVarargs = new TreeData<>();
+        TreeData<String> dataCollection = new TreeData<>();
+        TreeData<String> dataStream = new TreeData<>();
+
+        data.addItems(null, "a", "b", "c");
+        dataVarargs.addRootItems("a", "b", "c");
+        dataCollection.addRootItems(Arrays.asList("a", "b", "c"));
+        dataStream.addRootItems(Arrays.asList("a", "b", "c").stream());
+
+        Assert.assertEquals(data.getRootItems(), dataVarargs.getRootItems());
+        Assert.assertEquals(data.getRootItems(), dataCollection.getRootItems());
+        Assert.assertEquals(data.getRootItems(), dataStream.getRootItems());
+    }
+
     @Test
     public void populate_treeData_with_child_item_provider() {
         TreeData<String> stringData = new TreeData<>();
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