Implement SingleSelection on client and server

Change-Id: I48192de092c6b6e6be7ca2580720d2765962e167

2 files changed, 169 insertions, 0 deletions

diff --git a/shared/src/main/java/com/vaadin/shared/data/selection/SelectionModel.java b/shared/src/main/java/com/vaadin/shared/data/selection/SelectionModel.java
new file mode 100644
index 0000000000..8fff6ee434
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/data/selection/SelectionModel.java
@@ -0,0 +1,129 @@
+/*
+ * 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.shared.data.selection;
+
+import java.io.Serializable;
+import java.util.Collections;
+import java.util.Optional;
+import java.util.Set;
+
+/**
+ * Models the selection logic of a {@code Listing} component. Determines how
+ * items can be selected and deselected.
+ * 
+ * @author Vaadin Ltd.
+ * 
+ * @param <T>
+ *            the type of the items to select
+ * @since
+ */
+public interface SelectionModel<T> extends Serializable {
+
+    /**
+     * A selection model in which at most one item can be selected at a time.
+     * Selecting another item deselects the originally selected item.
+     *
+     * @param <T>
+     *            the type of the items to select
+     */
+    public interface Single<T> extends SelectionModel<T> {
+
+        /**
+         * Selects the given item. If another item was already selected, that
+         * item is deselected.
+         */
+        @Override
+        public void select(T item);
+
+        /**
+         * Returns the currently selected item, or an empty optional if no item
+         * is selected.
+         * 
+         * @return an optional of the selected item if any, an empty optional
+         *         otherwise
+         */
+        public Optional<T> getSelectedItem();
+
+        /**
+         * Returns a singleton set of the currently selected item or an empty
+         * set if no item is selected.
+         * 
+         * @return a singleton set of the selected item if any, an empty set
+         *         otherwise
+         */
+        @Override
+        default Set<T> getSelectedItems() {
+            return getSelectedItem().map(Collections::singleton)
+                    .orElse(Collections.emptySet());
+        }
+    }
+
+    /**
+     * A selection model in which multiple items can be selected at the same
+     * time. Selecting an item adds it to the selection.
+     *
+     * @param <T>
+     *            the type of the items to select
+     */
+    public interface Multi<T> extends SelectionModel<T> {
+
+        /**
+         * Adds the given items to the set of currently selected items.
+         */
+        @Override
+        public void select(T item);
+    }
+
+    /**
+     * Returns an immutable set of the currently selected items.
+     * <p>
+     * <i>Implementation note:</i> the iteration order of the items in the
+     * returned set should be well-defined and documented by the implementing
+     * class.
+     * 
+     * @return the items in the current selection, not null
+     */
+    public Set<T> getSelectedItems();
+
+    /**
+     * Selects the given item. Depending on the implementation, may cause other
+     * items to be deselected. If the item is already selected, does nothing.
+     * 
+     * @param item
+     *            the item to select, not null
+     */
+    public void select(T item);
+
+    /**
+     * Deselects the given item. If the item is not currently selected, does
+     * nothing.
+     * 
+     * @param item
+     *            the item to deselect, not null
+     */
+    public void deselect(T item);
+
+    /**
+     * Returns whether the given item is currently selected.
+     * 
+     * @param item
+     *            the item to check, not null
+     * @return {@code true} if the item is selected, {@code false} otherwise
+     */
+    public default boolean isSelected(T item) {
+        return getSelectedItems().contains(item);
+    }
+}
diff --git a/shared/src/main/java/com/vaadin/shared/data/selection/SelectionServerRpc.java b/shared/src/main/java/com/vaadin/shared/data/selection/SelectionServerRpc.java
new file mode 100644
index 0000000000..65cc55aebd
--- /dev/null
+++ b/shared/src/main/java/com/vaadin/shared/data/selection/SelectionServerRpc.java
@@ -0,0 +1,40 @@
+/*
+ * 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.shared.data.selection;
+
+import com.vaadin.shared.communication.ServerRpc;
+
+/**
+ * Transmits SelectionModel selection events from the client to the server.
+ */
+public interface SelectionServerRpc extends ServerRpc {
+
+    /**
+     * Selects an item based on its key.
+     * 
+     * @param key
+     *            the key of the item to select
+     */
+    void select(String key);
+
+    /**
+     * Deselects an item based on its key.
+     * 
+     * @param key
+     *            the key of the item to deselect
+     */
+    void deselect(String key);
+}