Vector cost proposed to TST on 2016-07-13
First part implemented: weight interface introduced and integrated, default weight implementation added.
Change-Id: Ia46f1b44139069aa171a3c13faf168351bd7cc56
diff --git a/utils/misc/src/main/java/org/onlab/graph/Weight.java b/utils/misc/src/main/java/org/onlab/graph/Weight.java
new file mode 100644
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+++ b/utils/misc/src/main/java/org/onlab/graph/Weight.java
@@ -0,0 +1,55 @@
+/*
+ * Copyright 2016-present 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.graph;
+
+/**
+ * Abstraction of a graph edge weight.
+ */
+public interface Weight extends Comparable<Weight> {
+
+ /**
+ * Merges the given weight with this one returning a new aggregated
+ * weight.
+ *
+ * @param otherWeight weight to add
+ * @return aggregated weight
+ */
+ Weight merge(Weight otherWeight);
+
+ /**
+ * Subtracts the given weight from this one and produces a new weight.
+ *
+ * @param otherWeight weight to subtract
+ * @return residual weight
+ */
+ Weight subtract(Weight otherWeight);
+
+ /**
+ * Returns true if the weighted subject (link/path) can be traversed; false otherwise.
+ *
+ * @return true if weight is adequate, false if weight is infinite
+ */
+ boolean isViable();
+
+ /**
+ * Returns true if the weight is negative (means that aggregated
+ * path cost will decrease if we add weighted subject to it).
+ *
+ * @return true if the weight is negative, false otherwise
+ */
+ boolean isNegative();
+}