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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.ImmutableSet;
import com.google.common.collect.ImmutableSetMultimap;
import java.util.Objects;
import java.util.Set;
import static com.google.common.base.MoreObjects.toStringHelper;
import static com.google.common.base.Preconditions.checkNotNull;
/**
* Immutable graph implemented using adjacency lists.
*
* @param <V> vertex type
* @param <E> edge type
*/
public class AdjacencyListsGraph<V extends Vertex, E extends Edge<V>>
implements Graph<V, E> {
private final Set<V> vertexes;
private final Set<E> edges;
private final ImmutableSetMultimap<V, E> sources;
private final ImmutableSetMultimap<V, E> destinations;
/**
* Creates a graph comprising of the specified vertexes and edges.
*
* @param vertexes set of graph vertexes
* @param edges set of graph edges
*/
public AdjacencyListsGraph(Set<V> vertexes, Set<E> edges) {
checkNotNull(vertexes, "Vertex set cannot be null");
checkNotNull(edges, "Edge set cannot be null");
// Record ingress/egress edges for each vertex.
ImmutableSetMultimap.Builder<V, E> srcMap = ImmutableSetMultimap.builder();
ImmutableSetMultimap.Builder<V, E> dstMap = ImmutableSetMultimap.builder();
// Also make sure that all edge end-points are added as vertexes
ImmutableSet.Builder<V> actualVertexes = ImmutableSet.builder();
actualVertexes.addAll(vertexes);
for (E edge : edges) {
srcMap.put(edge.src(), edge);
actualVertexes.add(edge.src());
dstMap.put(edge.dst(), edge);
actualVertexes.add(edge.dst());
}
// Make an immutable copy of the edge and vertex sets
this.edges = ImmutableSet.copyOf(edges);
this.vertexes = actualVertexes.build();
// Build immutable copies of sources and destinations edge maps
sources = srcMap.build();
destinations = dstMap.build();
}
@Override
public Set<V> getVertexes() {
return vertexes;
}
@Override
public Set<E> getEdges() {
return edges;
}
@Override
public Set<E> getEdgesFrom(V src) {
return sources.get(src);
}
@Override
public Set<E> getEdgesTo(V dst) {
return destinations.get(dst);
}
@Override
public boolean equals(Object obj) {
if (this == obj) {
return true;
}
if (obj instanceof AdjacencyListsGraph) {
AdjacencyListsGraph that = (AdjacencyListsGraph) obj;
return this.getClass() == that.getClass() &&
Objects.equals(this.vertexes, that.vertexes) &&
Objects.equals(this.edges, that.edges);
}
return false;
}
@Override
public int hashCode() {
return Objects.hash(vertexes, edges);
}
@Override
public String toString() {
return toStringHelper(this)
.add("vertexes", vertexes)
.add("edges", edges)
.toString();
}
}
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