Created ToggleSelectionModel for mobile device selection

java/com.sap.sailing.gwt.ui/src/main/java/com/sap/sailing/gwt/ui/leaderboard/ToggleSelectionModel.java

@@ -0,0 +1,92 @@
+package com.sap.sailing.gwt.ui.leaderboard;
+
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.Map;
+import java.util.Set;
+
+import com.google.gwt.view.client.ProvidesKey;
+import com.google.gwt.view.client.SelectionChangeEvent;
+import com.google.gwt.view.client.SelectionModel.AbstractSelectionModel;
+
+public class ToggleSelectionModel<T> extends AbstractSelectionModel<T> {
+
+    // Ensure one value per key
+    private final HashMap<Object, T> selectedSet = new HashMap<Object, T>();
+
+    private final HashMap<T, Boolean> selectionChanges = new HashMap<T, Boolean>();
+    
+    public ToggleSelectionModel() {
+        this(null);
+    }
+
+    public ToggleSelectionModel(ProvidesKey<T> keyProvider) {
+        super(keyProvider);
+    }
+
+    /**
+     * Get the set of selected items as a copy.
+     *
+     * @return the set of selected items
+     */
+    public Set<T> getSelectedSet() {
+      resolveChanges();
+      return new HashSet<T>(selectedSet.values());
+    }
+
+    @Override
+    public boolean isSelected(T object) {
+//        resolveChanges();
+        return selectedSet.containsKey(getKey(object));
+    }
+
+    @Override
+    public void setSelected(T object, boolean selected) {
+        if (selected) {
+            selectionChanges.put(object, !isSelected(object));
+            scheduleSelectionChangeEvent();
+        }
+    }
+
+    @Override
+    protected void fireSelectionChangeEvent() {
+      if (isEventScheduled()) {
+        setEventCancelled(true);
+      }
+      resolveChanges();
+    }
+    
+    private void resolveChanges() {
+        //TODO
+        if (selectionChanges.isEmpty()) {
+            return;
+          }
+
+          boolean changed = false;
+          for (Map.Entry<T, Boolean> entry : selectionChanges.entrySet()) {
+            T object = entry.getKey();
+            boolean selected = entry.getValue();
+
+            Object key = getKey(object);
+            T oldValue = selectedSet.get(key);
+            if (selected) {
+              if (oldValue == null || !oldValue.equals(object)) {
+                selectedSet.put(getKey(object), object);
+                changed = true;
+              }
+            } else {
+              if (oldValue != null) {
+                selectedSet.remove(key);
+                changed = true;
+              }
+            }
+          }
+          selectionChanges.clear();
+
+          // Fire a selection change event.
+          if (changed) {
+            SelectionChangeEvent.fire(this);
+          }
+    }
+
+}