1 files changed, 116 insertions, 0 deletions
diff --git a/framework/src/onos/web/gui/src/main/java/org/onosproject/ui/impl/TopoOverlayCache.java b/framework/src/onos/web/gui/src/main/java/org/onosproject/ui/impl/TopoOverlayCache.java
new file mode 100644
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--- /dev/null
+++ b/framework/src/onos/web/gui/src/main/java/org/onosproject/ui/impl/TopoOverlayCache.java
@@ -0,0 +1,116 @@
+/*
+ * Copyright 2015 Open Networking Laboratory
+ *
+ * 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 org.onosproject.ui.impl;
+
+import org.onosproject.ui.UiTopoOverlay;
+
+import java.util.HashMap;
+import java.util.Map;
+
+import static com.google.common.base.Strings.isNullOrEmpty;
+
+/**
+ * A cache of {@link org.onosproject.ui.UiTopoOverlay}'s that were registered
+ * at the time the UI connection was established.
+ */
+public class TopoOverlayCache {
+
+    private static final String EMPTY = "";
+    private static final UiTopoOverlay NONE = new NullOverlay();
+
+    private final Map<String, UiTopoOverlay> overlays = new HashMap<>();
+    private UiTopoOverlay current = NONE;
+
+    public TopoOverlayCache() {
+        overlays.put(null, NONE);
+    }
+
+    /**
+     * Adds a topology overlay to the cache.
+     *
+     * @param overlay   a topology overlay
+     */
+    public void add(UiTopoOverlay overlay) {
+        overlays.put(overlay.id(), overlay);
+    }
+
+    /**
+     * Invoked when the cache is no longer needed.
+     */
+    public void destroy() {
+        overlays.clear();
+    }
+
+    /**
+     * Switching currently selected overlay.
+     *
+     * @param deact identity of overlay to deactivate
+     * @param act identity of overlay to activate
+     */
+    public void switchOverlay(String deact, String act) {
+        UiTopoOverlay toDeactivate = getOverlay(deact);
+        UiTopoOverlay toActivate = getOverlay(act);
+
+        toDeactivate.deactivate();
+        current = toActivate;
+        current.activate();
+    }
+
+    private UiTopoOverlay getOverlay(String id) {
+        return isNullOrEmpty(id) ? NONE : overlays.get(id);
+    }
+
+    /**
+     * Returns the current overlay instance.
+     * Note that this method always returns a reference; when there is no
+     * overlay selected the "NULL" overlay instance is returned.
+     *
+     * @return the current overlay
+     */
+    public UiTopoOverlay currentOverlay() {
+        return current;
+    }
+
+    /**
+     * Returns the number of overlays in the cache. Remember that this
+     * includes the "NULL" overlay, representing "no overlay selected".
+     *
+     * @return number of overlays
+     */
+    public int size() {
+        return overlays.size();
+    }
+
+    /**
+     * Returns true if the identifier of the currently active overlay
+     * matches the given parameter.
+     *
+     * @param overlayId overlay identifier
+     * @return true if this matches the ID of currently active overlay
+     */
+    public boolean isActive(String overlayId) {
+        return currentOverlay().id().equals(overlayId);
+    }
+
+    // overlay instance representing "no overlay selected"
+    private static class NullOverlay extends UiTopoOverlay {
+        public NullOverlay() {
+            super(EMPTY);
+        }
+    }
+}