| /* |
| * Copyright 2016-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.onlab.graph; |
| |
| import static com.google.common.base.MoreObjects.toStringHelper; |
| |
| import com.google.common.math.DoubleMath; |
| |
| import java.util.Objects; |
| |
| /** |
| * Weight implementation based on a double value. |
| */ |
| public class ScalarWeight implements Weight { |
| |
| /** |
| * Instance of scalar weight to mark links/paths which |
| * can not be traversed. |
| */ |
| public static final ScalarWeight NON_VIABLE_WEIGHT = |
| new ScalarWeight(Double.POSITIVE_INFINITY); |
| |
| private static double samenessThreshold = Double.MIN_VALUE; |
| |
| private final double value; |
| |
| /** |
| * Creates a new scalar weight with the given double value. |
| * @param value double value |
| * @return scalar weight instance |
| */ |
| public static ScalarWeight toWeight(double value) { |
| return new ScalarWeight(value); |
| } |
| |
| /** |
| * Creates a new scalar weight with the given double value. |
| * @param value double value |
| */ |
| public ScalarWeight(double value) { |
| this.value = value; |
| } |
| |
| @Override |
| public Weight merge(Weight otherWeight) { |
| return new ScalarWeight(value + ((ScalarWeight) otherWeight).value); |
| } |
| |
| @Override |
| public Weight subtract(Weight otherWeight) { |
| return new ScalarWeight(value - ((ScalarWeight) otherWeight).value); |
| } |
| |
| @Override |
| public boolean isViable() { |
| return !this.equals(NON_VIABLE_WEIGHT); |
| } |
| |
| @Override |
| public int compareTo(Weight otherWeight) { |
| //check equality with samenessThreshold |
| if (equals(otherWeight)) { |
| return 0; |
| } |
| return Double.compare(value, ((ScalarWeight) otherWeight).value); |
| } |
| |
| @Override |
| public boolean equals(Object obj) { |
| return ((obj instanceof ScalarWeight) && |
| (DoubleMath.fuzzyEquals(value, ((ScalarWeight) obj).value, |
| samenessThreshold))); |
| } |
| |
| @Override |
| public int hashCode() { |
| return Objects.hash(value); |
| } |
| |
| @Override |
| public boolean isNegative() { |
| return value < 0; |
| } |
| |
| @Override |
| public String toString() { |
| return toStringHelper(this).add("value", value).toString(); |
| } |
| |
| /** |
| * Returns inner double value. |
| * |
| * @return double value |
| */ |
| public double value() { |
| return value; |
| } |
| |
| /** |
| * Sets a new sameness threshold for comparing cost values; default is |
| * is {@link Double#MIN_VALUE}. |
| * |
| * @param threshold fractional double value |
| */ |
| public static void setSamenessThreshold(double threshold) { |
| samenessThreshold = threshold; |
| } |
| |
| /** |
| * Returns the current sameness threshold for comparing cost values. |
| * |
| * @return current threshold |
| */ |
| public static double samenessThreshold() { |
| return samenessThreshold; |
| } |
| } |