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/*
* 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.graph;
import com.google.common.collect.ImmutableList;
import java.util.ArrayList;
import java.util.List;
import java.util.Objects;
import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* Simple concrete implementation of a directed graph path.
*/
public class DefaultMutablePath<V extends Vertex, E extends Edge<V>> implements MutablePath<V, E> {
private final List<E> edges = new ArrayList<>();
private double cost = 0.0;
/**
* Creates a new empty path.
*/
public DefaultMutablePath() {
}
/**
* Creates a new path as a copy of another path.
*
* @param path path to be copied
*/
public DefaultMutablePath(Path<V, E> path) {
checkNotNull(path, "Path cannot be null");
this.cost = path.cost();
edges.addAll(path.edges());
}
@Override
public V src() {
return edges.isEmpty() ? null : edges.get(0).src();
}
@Override
public V dst() {
return edges.isEmpty() ? null : edges.get(edges.size() - 1).dst();
}
@Override
public double cost() {
return cost;
}
@Override
public List<E> edges() {
return ImmutableList.copyOf(edges);
}
@Override
public void setCost(double cost) {
this.cost = cost;
}
@Override
public Path<V, E> toImmutable() {
return new DefaultPath<>(edges, cost);
}
@Override
public void insertEdge(E edge) {
checkNotNull(edge, "Edge cannot be null");
checkArgument(edges.isEmpty() || src().equals(edge.dst()),
"Edge destination must be the same as the current path source");
edges.add(0, edge);
}
@Override
public void appendEdge(E edge) {
checkNotNull(edge, "Edge cannot be null");
checkArgument(edges.isEmpty() || dst().equals(edge.src()),
"Edge source must be the same as the current path destination");
edges.add(edge);
}
@Override
public void removeEdge(E edge) {
checkArgument(edge.src().equals(edge.dst()) ||
edges.indexOf(edge) == 0 ||
edges.lastIndexOf(edge) == edges.size() - 1,
"Edge must be at start or end of path, or it must be a cyclic edge");
edges.remove(edge);
}
@Override
public String toString() {
return toStringHelper(this)
.add("src", src())
.add("dst", dst())
.add("cost", cost)
.add("edges", edges)
.toString();
}
@Override
public int hashCode() {
return Objects.hash(edges, cost);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof DefaultMutablePath) {
final DefaultMutablePath other = (DefaultMutablePath) obj;
return Objects.equals(this.cost, other.cost) &&
Objects.equals(this.edges, other.edges);
}
return false;
}
}
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