Add constraint for waypoints

Change-Id: I8156920d4d3d85aee060b9d0fe925f43f9b15ff1

@@ -40,6 +40,10 @@
             <groupId>joda-time</groupId>
             <artifactId>joda-time</artifactId>
         </dependency>
+        <dependency>
+            <groupId>org.easymock</groupId>
+            <artifactId>easymock</artifactId>
+        </dependency>
     </dependencies>
 
 </project>

+/*
+ * Copyright 2014 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.onlab.onos.net.intent.constraint;
+
+import com.google.common.base.MoreObjects;
+import com.google.common.collect.ImmutableList;
+import org.onlab.onos.net.ElementId;
+import org.onlab.onos.net.Link;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.intent.Constraint;
+import org.onlab.onos.net.resource.LinkResourceService;
+
+import java.util.LinkedList;
+import java.util.List;
+import java.util.Objects;
+
+import static com.google.common.base.Preconditions.checkArgument;
+import static com.google.common.base.Preconditions.checkNotNull;
+
+/**
+ * Constraint that evaluates elements passed through in order.
+ */
+public class WaypointConstraint implements Constraint {
+
+    private final List<ElementId> waypoints;
+
+    /**
+     * Creates a new waypoint constraint.
+     *
+     * @param waypoints waypoints
+     */
+    public WaypointConstraint(ElementId... waypoints) {
+        checkNotNull(waypoints, "waypoints cannot be null");
+        checkArgument(waypoints.length > 0, "length of waypoints should be more than 0");
+        this.waypoints = ImmutableList.copyOf(waypoints);
+    }
+
+    @Override
+    public double cost(Link link, LinkResourceService resourceService) {
+        // Always consider the number of hops
+        return 1;
+    }
+
+    @Override
+    public boolean validate(Path path, LinkResourceService resourceService) {
+        LinkedList<ElementId> waypoints = new LinkedList<>(this.waypoints);
+        ElementId current = waypoints.poll();
+        // This is safe because Path class ensures the number of links are more than 0
+        Link firstLink = path.links().get(0);
+        if (firstLink.src().elementId().equals(current)) {
+            current = waypoints.poll();
+        }
+
+        for (Link link : path.links()) {
+            if (link.dst().elementId().equals(current)) {
+                current = waypoints.poll();
+                // Empty waypoints means passing through all waypoints in the specified order
+                if (current == null) {
+                    return true;
+                }
+            }
+        }
+
+        return false;
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(waypoints);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+
+        if (!(obj instanceof WaypointConstraint)) {
+            return false;
+        }
+
+        final WaypointConstraint that = (WaypointConstraint) obj;
+        return Objects.equals(this.waypoints, that.waypoints);
+    }
+
+    @Override
+    public String toString() {
+        return MoreObjects.toStringHelper(this)
+                .add("waypoints", waypoints)
+                .toString();
+    }
+}

+/*
+ * Copyright 2014 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.onlab.onos.net.intent.constraint;
+
+import org.junit.Before;
+import org.junit.Test;
+import org.onlab.onos.net.DefaultLink;
+import org.onlab.onos.net.DefaultPath;
+import org.onlab.onos.net.DeviceId;
+import org.onlab.onos.net.Path;
+import org.onlab.onos.net.PortNumber;
+import org.onlab.onos.net.provider.ProviderId;
+import org.onlab.onos.net.resource.LinkResourceService;
+
+import java.util.Arrays;
+
+import static org.easymock.EasyMock.createMock;
+import static org.hamcrest.Matchers.is;
+import static org.junit.Assert.assertThat;
+import static org.onlab.onos.net.DefaultLinkTest.cp;
+import static org.onlab.onos.net.DeviceId.deviceId;
+import static org.onlab.onos.net.Link.Type.DIRECT;
+
+/**
+ * Test for constraint of intermediate elements.
+ */
+public class WaypointConstraintTest {
+
+    public static final DeviceId DID1 = deviceId("of:1");
+    public static final DeviceId DID2 = deviceId("of:2");
+    public static final DeviceId DID3 = deviceId("of:3");
+    public static final DeviceId DID4 = deviceId("of:4");
+    public static final PortNumber PN1 = PortNumber.portNumber(1);
+    public static final PortNumber PN2 = PortNumber.portNumber(2);
+    public static final PortNumber PN3 = PortNumber.portNumber(3);
+    public static final PortNumber PN4 = PortNumber.portNumber(4);
+    public static final ProviderId PROVIDER_ID = new ProviderId("of", "foo");
+
+    private WaypointConstraint sut;
+    private LinkResourceService linkResourceService;
+
+    private Path path;
+    private DefaultLink link2;
+    private DefaultLink link1;
+
+    @Before
+    public void setUp() {
+        linkResourceService = createMock(LinkResourceService.class);
+
+        link1 = new DefaultLink(PROVIDER_ID, cp(DID1, PN1), cp(DID2, PN2), DIRECT);
+        link2 = new DefaultLink(PROVIDER_ID, cp(DID2, PN3), cp(DID3, PN4), DIRECT);
+        path = new DefaultPath(PROVIDER_ID, Arrays.asList(link1, link2), 10);
+    }
+
+    /**
+     * Tests that all of the specified waypoints are included in the specified path in order.
+     */
+    @Test
+    public void testSatisfyWaypoints() {
+        sut = new WaypointConstraint(DID1, DID2, DID3);
+
+        assertThat(sut.validate(path, linkResourceService), is(true));
+    }
+
+    /**
+     * Tests that the specified path does not includes the specified waypoint.
+     */
+    @Test
+    public void testNotSatisfyWaypoint() {
+        sut = new WaypointConstraint(DID4);
+
+        assertThat(sut.validate(path, linkResourceService), is(false));
+    }
+}