com.google.common.graph.ImmutableNetwork Maven / Gradle / Ivy
/*
* Copyright (C) 2014 The Guava Authors
*
* 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 com.google.common.graph;
import static com.google.common.base.Preconditions.checkNotNull;
import com.google.common.annotations.Beta;
import com.google.common.base.Function;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.Maps;
import com.google.errorprone.annotations.Immutable;
import java.util.Map;
/**
* A {@link Network} whose elements and structural relationships will never change. Instances of
* this class may be obtained with {@link #copyOf(Network)}.
*
* See the Guava User's Guide's discussion
* of the {@code Immutable*} types for more information on the properties and guarantees
* provided by this class.
*
* @author James Sexton
* @author Joshua O'Madadhain
* @author Omar Darwish
* @param Node parameter type
* @param Edge parameter type
* @since 20.0
*/
@Beta
@Immutable(containerOf = {"N", "E"})
@SuppressWarnings("Immutable") // Extends ConfigurableNetwork but uses ImmutableMaps.
public final class ImmutableNetwork extends ConfigurableNetwork {
private ImmutableNetwork(Network network) {
super(
NetworkBuilder.from(network), getNodeConnections(network), getEdgeToReferenceNode(network));
}
/** Returns an immutable copy of {@code network}. */
public static ImmutableNetwork copyOf(Network network) {
return (network instanceof ImmutableNetwork)
? (ImmutableNetwork) network
: new ImmutableNetwork(network);
}
/**
* Simply returns its argument.
*
* @deprecated no need to use this
*/
@Deprecated
public static ImmutableNetwork copyOf(ImmutableNetwork network) {
return checkNotNull(network);
}
@Override
public ImmutableGraph asGraph() {
return new ImmutableGraph(super.asGraph()); // safe because the view is effectively immutable
}
private static Map> getNodeConnections(Network network) {
// ImmutableMap.Builder maintains the order of the elements as inserted, so the map will have
// whatever ordering the network's nodes do, so ImmutableSortedMap is unnecessary even if the
// input nodes are sorted.
ImmutableMap.Builder> nodeConnections = ImmutableMap.builder();
for (N node : network.nodes()) {
nodeConnections.put(node, connectionsOf(network, node));
}
return nodeConnections.build();
}
private static Map getEdgeToReferenceNode(Network network) {
// ImmutableMap.Builder maintains the order of the elements as inserted, so the map will have
// whatever ordering the network's edges do, so ImmutableSortedMap is unnecessary even if the
// input edges are sorted.
ImmutableMap.Builder edgeToReferenceNode = ImmutableMap.builder();
for (E edge : network.edges()) {
edgeToReferenceNode.put(edge, network.incidentNodes(edge).nodeU());
}
return edgeToReferenceNode.build();
}
private static NetworkConnections connectionsOf(Network network, N node) {
if (network.isDirected()) {
Map inEdgeMap = Maps.asMap(network.inEdges(node), sourceNodeFn(network));
Map outEdgeMap = Maps.asMap(network.outEdges(node), targetNodeFn(network));
int selfLoopCount = network.edgesConnecting(node, node).size();
return network.allowsParallelEdges()
? DirectedMultiNetworkConnections.ofImmutable(inEdgeMap, outEdgeMap, selfLoopCount)
: DirectedNetworkConnections.ofImmutable(inEdgeMap, outEdgeMap, selfLoopCount);
} else {
Map incidentEdgeMap =
Maps.asMap(network.incidentEdges(node), adjacentNodeFn(network, node));
return network.allowsParallelEdges()
? UndirectedMultiNetworkConnections.ofImmutable(incidentEdgeMap)
: UndirectedNetworkConnections.ofImmutable(incidentEdgeMap);
}
}
private static Function sourceNodeFn(final Network network) {
return new Function() {
@Override
public N apply(E edge) {
return network.incidentNodes(edge).source();
}
};
}
private static Function targetNodeFn(final Network network) {
return new Function() {
@Override
public N apply(E edge) {
return network.incidentNodes(edge).target();
}
};
}
private static Function adjacentNodeFn(final Network network, final N node) {
return new Function() {
@Override
public N apply(E edge) {
return network.incidentNodes(edge).adjacentNode(node);
}
};
}
}