Add initial implementation of TreeGrid (#8572)

* Add initial implementation of TreeGrid

* Refactor TreeGrid and related classes

* Fix potential class cast exception in TreeGrid#getDataProvider

* Add smoke tests for TreeGrid

* Add communication constants for TreeGrid

Use shared constant values for hierarchy data serialization and deserialization

* Fix event ordering in TreeGrid, add javadocs, keyboard navigation test

* TreeGrid improvements

* Add TreeGrid.getDataProvider to StateGetDoesNotMarkDirtyTest exclude list

* Merge remote-tracking branch 'github/master' into tree-grid

* Remove getEscalator override from TreeGrid

4 files changed, 205 insertions, 1 deletions

diff --git a/server/src/main/java/com/vaadin/data/provider/HierarchicalDataProvider.java b/server/src/main/java/com/vaadin/data/provider/HierarchicalDataProvider.java
new file mode 100644
index 0000000000..ec54a3a138
--- /dev/null
+++ b/server/src/main/java/com/vaadin/data/provider/HierarchicalDataProvider.java
@@ -0,0 +1,39 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.data.provider;
+
+/**
+ * 
+ * @author Vaadin Ltd
+ * @since 8.1
+ * 
+ * @param <T>
+ * @param <F>
+ */
+public interface HierarchicalDataProvider<T, F> extends DataProvider<T, F> {
+
+    public int getDepth(T item);
+
+    public boolean isRoot(T item);
+
+    public T getParent(T item);
+
+    public boolean isCollapsed(T item);
+
+    public boolean hasChildren(T item);
+
+    public void setCollapsed(T item, boolean b);
+}
diff --git a/server/src/main/java/com/vaadin/ui/Grid.java b/server/src/main/java/com/vaadin/ui/Grid.java
index 186be328f4..c3456075c3 100644
--- a/server/src/main/java/com/vaadin/ui/Grid.java
+++ b/server/src/main/java/com/vaadin/ui/Grid.java
@@ -646,7 +646,7 @@ public class Grid<T> extends AbstractListing<T> implements HasComponents,
                 Type type = null;
                 try {
                     type = getState(false).getClass()
-                            .getDeclaredField(diffStateKey).getGenericType();
+                            .getField(diffStateKey).getGenericType();
                 } catch (NoSuchFieldException | SecurityException e) {
                     e.printStackTrace();
                 }
diff --git a/server/src/main/java/com/vaadin/ui/TreeGrid.java b/server/src/main/java/com/vaadin/ui/TreeGrid.java
new file mode 100644
index 0000000000..f438df4e8f
--- /dev/null
+++ b/server/src/main/java/com/vaadin/ui/TreeGrid.java
@@ -0,0 +1,164 @@
+/*
+ * Copyright 2000-2016 Vaadin Ltd.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not
+ * use this file except in compliance with the License. You may obtain a copy of
+ * the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+ * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+ * License for the specific language governing permissions and limitations under
+ * the License.
+ */
+package com.vaadin.ui;
+
+import java.util.Collection;
+import java.util.Objects;
+import java.util.stream.Stream;
+
+import com.vaadin.data.provider.DataProvider;
+import com.vaadin.data.provider.HierarchicalDataProvider;
+import com.vaadin.shared.ui.treegrid.NodeCollapseRpc;
+import com.vaadin.shared.ui.treegrid.TreeGridCommunicationConstants;
+import com.vaadin.shared.ui.treegrid.TreeGridState;
+
+import elemental.json.Json;
+import elemental.json.JsonObject;
+
+/**
+ * A grid component for displaying hierarchical tabular data.
+ * 
+ * @author Vaadin Ltd
+ * @since 8.1
+ * 
+ * @param <T>
+ *            the grid bean type
+ */
+public class TreeGrid<T> extends Grid<T> {
+
+    public TreeGrid() {
+        super();
+
+        // Attaches hierarchy data to the row
+        addDataGenerator((item, rowData) -> {
+
+            JsonObject hierarchyData = Json.createObject();
+            hierarchyData.put(TreeGridCommunicationConstants.ROW_DEPTH,
+                    getDataProvider().getDepth(item));
+
+            boolean isLeaf = !getDataProvider().hasChildren(item);
+            if (isLeaf) {
+                hierarchyData.put(TreeGridCommunicationConstants.ROW_LEAF,
+                        true);
+            } else {
+                hierarchyData.put(TreeGridCommunicationConstants.ROW_COLLAPSED,
+                        getDataProvider().isCollapsed(item));
+                hierarchyData.put(TreeGridCommunicationConstants.ROW_LEAF,
+                        false);
+            }
+
+            // add hierarchy information to row as metadata
+            rowData.put(
+                    TreeGridCommunicationConstants.ROW_HIERARCHY_DESCRIPTION,
+                    hierarchyData);
+        });
+
+        registerRpc(new NodeCollapseRpc() {
+            @Override
+            public void toggleCollapse(String rowKey) {
+                T item = getDataCommunicator().getKeyMapper().get(rowKey);
+                TreeGrid.this.toggleCollapse(item);
+            }
+        });
+    }
+
+    // TODO: construct a "flat" in memory hierarchical data provider?
+    @Override
+    public void setItems(Collection<T> items) {
+        throw new UnsupportedOperationException("Not implemented");
+    }
+
+    @Override
+    public void setItems(Stream<T> items) {
+        throw new UnsupportedOperationException("Not implemented");
+    }
+
+    @Override
+    public void setItems(T... items) {
+        throw new UnsupportedOperationException("Not implemented");
+    }
+
+    @Override
+    public void setDataProvider(DataProvider<T, ?> dataProvider) {
+        if (!(dataProvider instanceof HierarchicalDataProvider)) {
+            throw new IllegalArgumentException(
+                    "TreeGrid only accepts hierarchical data providers");
+        }
+        super.setDataProvider(dataProvider);
+    }
+
+    /**
+     * Set the column that displays the hierarchy of this grid's data. By
+     * default the hierarchy will be displayed in the first column.
+     * <p>
+     * Setting a hierarchy column by calling this method also sets the column to
+     * be visible and not hidable.
+     * 
+     * @see Column#setId(String)
+     * 
+     * @param id
+     *            id of the column to use for displaying hierarchy
+     */
+    public void setHierarchyColumn(String id) {
+        Objects.requireNonNull(id, "id may not be null");
+        if (getColumn(id) == null) {
+            throw new IllegalArgumentException("No column found for given id");
+        }
+        getColumn(id).setHidden(false);
+        getColumn(id).setHidable(false);
+        getState().hierarchyColumnId = getInternalIdForColumn(getColumn(id));
+    }
+
+    @Override
+    protected TreeGridState getState() {
+        return (TreeGridState) super.getState();
+    }
+
+    @Override
+    protected TreeGridState getState(boolean markAsDirty) {
+        return (TreeGridState) super.getState(markAsDirty);
+    }
+
+    /**
+     * Toggle the expansion of an item in this grid. If the item is already
+     * expanded, it will be collapsed.
+     * <p>
+     * Toggling expansion on a leaf item in the hierarchy will have no effect.
+     * 
+     * @param item
+     *            the item to toggle expansion for
+     */
+    public void toggleCollapse(T item) {
+        getDataProvider().setCollapsed(item,
+                !getDataProvider().isCollapsed(item));
+        getDataCommunicator().reset();
+    }
+
+    @Override
+    public HierarchicalDataProvider<T, ?> getDataProvider() {
+        DataProvider<T, ?> dataProvider = super.getDataProvider();
+        // FIXME DataCommunicator by default has a CallbackDataProvider if no
+        // DataProvider is set, resulting in a class cast exception if we don't
+        // check it here.
+
+        // Once fixed, remove this method from the exclude list in
+        // StateGetDoesNotMarkDirtyTest
+        if (!(dataProvider instanceof HierarchicalDataProvider)) {
+            throw new IllegalStateException("No data provider has been set.");
+        }
+        return (HierarchicalDataProvider<T, ?>) dataProvider;
+    }
+}
diff --git a/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java b/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java
index 7a11cf4df6..3b4c2413f9 100644
--- a/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java
+++ b/server/src/test/java/com/vaadin/tests/server/component/StateGetDoesNotMarkDirtyTest.java
@@ -31,6 +31,7 @@ public class StateGetDoesNotMarkDirtyTest {
         excludedMethods.add("getConnectorId");
         excludedMethods.add("getContent");
         excludedMethods.add("com.vaadin.ui.Grid:getSelectAllCheckBoxVisible");
+        excludedMethods.add("com.vaadin.ui.TreeGrid:getDataProvider");
     }
 
     @Test