Add constraint for waypoints
Change-Id: I8156920d4d3d85aee060b9d0fe925f43f9b15ff1
diff --git a/core/api/src/main/java/org/onlab/onos/net/intent/constraint/WaypointConstraint.java b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/WaypointConstraint.java
new file mode 100644
index 0000000..fffb66c
--- /dev/null
+++ b/core/api/src/main/java/org/onlab/onos/net/intent/constraint/WaypointConstraint.java
@@ -0,0 +1,105 @@
+/*
+ * 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();
+ }
+}