initial code for the mac-learning app

Change-Id: I04f3b17c453e502f20477e83cb7cdc796b4160ae
diff --git a/app/src/main/java/org/opencord/maclearner/app/cli/MappedDeviceIdCompleter.java b/app/src/main/java/org/opencord/maclearner/app/cli/MappedDeviceIdCompleter.java
new file mode 100644
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--- /dev/null
+++ b/app/src/main/java/org/opencord/maclearner/app/cli/MappedDeviceIdCompleter.java
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+/*
+ * Copyright 2017-present Open Networking Foundation
+ *
+ * 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.opencord.maclearner.app.cli;
+
+import org.apache.karaf.shell.api.action.lifecycle.Service;
+import org.apache.karaf.shell.api.console.CommandLine;
+import org.apache.karaf.shell.api.console.Completer;
+import org.apache.karaf.shell.api.console.Session;
+import org.apache.karaf.shell.support.completers.StringsCompleter;
+import org.onosproject.cli.AbstractShellCommand;
+import org.opencord.maclearner.api.MacLearnerService;
+import org.onosproject.net.DeviceId;
+
+import java.util.Iterator;
+import java.util.List;
+import java.util.SortedSet;
+
+/**
+ * CLI completer for mapped device ids.
+ */
+@Service
+public class MappedDeviceIdCompleter implements Completer {
+
+    @Override
+    public int complete(Session session, CommandLine commandLine, List<String> candidates) {
+        // Delegate string completer
+        StringsCompleter delegate = new StringsCompleter();
+        MacLearnerService macLearnerService = AbstractShellCommand.get(MacLearnerService.class);
+        Iterator<DeviceId> it = macLearnerService.getMappedDevices().iterator();
+        SortedSet<String> strings = delegate.getStrings();
+
+        while (it.hasNext()) {
+            strings.add(it.next().toString());
+        }
+
+        // Now let the completer do the work for figuring out what to offer.
+        return delegate.complete(session, commandLine, candidates);
+    }
+
+}