| /* |
| * 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.CanIgnoreReturnValue; |
| 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)}. |
| * |
| * <p>See the Guava User's Guide's <a |
| * href="https://github.com/google/guava/wiki/GraphsExplained#immutable-implementations">discussion |
| * of the {@code Immutable*} types</a> for more information on the properties and guarantees |
| * provided by this class. |
| * |
| * @author James Sexton |
| * @author Joshua O'Madadhain |
| * @author Omar Darwish |
| * @author Jens Nyman |
| * @param <N> Node parameter type |
| * @param <E> Edge parameter type |
| * @since 20.0 |
| */ |
| @Beta |
| @Immutable(containerOf = {"N", "E"}) |
| @SuppressWarnings("Immutable") // Extends StandardNetwork but uses ImmutableMaps. |
| public final class ImmutableNetwork<N, E> extends StandardNetwork<N, E> { |
| |
| private ImmutableNetwork(Network<N, E> network) { |
| super( |
| NetworkBuilder.from(network), getNodeConnections(network), getEdgeToReferenceNode(network)); |
| } |
| |
| /** Returns an immutable copy of {@code network}. */ |
| public static <N, E> ImmutableNetwork<N, E> copyOf(Network<N, E> network) { |
| return (network instanceof ImmutableNetwork) |
| ? (ImmutableNetwork<N, E>) network |
| : new ImmutableNetwork<N, E>(network); |
| } |
| |
| /** |
| * Simply returns its argument. |
| * |
| * @deprecated no need to use this |
| */ |
| @Deprecated |
| public static <N, E> ImmutableNetwork<N, E> copyOf(ImmutableNetwork<N, E> network) { |
| return checkNotNull(network); |
| } |
| |
| @Override |
| public ImmutableGraph<N> asGraph() { |
| return new ImmutableGraph<N>(super.asGraph()); // safe because the view is effectively immutable |
| } |
| |
| private static <N, E> Map<N, NetworkConnections<N, E>> getNodeConnections(Network<N, E> 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<N, NetworkConnections<N, E>> nodeConnections = ImmutableMap.builder(); |
| for (N node : network.nodes()) { |
| nodeConnections.put(node, connectionsOf(network, node)); |
| } |
| return nodeConnections.build(); |
| } |
| |
| private static <N, E> Map<E, N> getEdgeToReferenceNode(Network<N, E> 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<E, N> edgeToReferenceNode = ImmutableMap.builder(); |
| for (E edge : network.edges()) { |
| edgeToReferenceNode.put(edge, network.incidentNodes(edge).nodeU()); |
| } |
| return edgeToReferenceNode.build(); |
| } |
| |
| private static <N, E> NetworkConnections<N, E> connectionsOf(Network<N, E> network, N node) { |
| if (network.isDirected()) { |
| Map<E, N> inEdgeMap = Maps.asMap(network.inEdges(node), sourceNodeFn(network)); |
| Map<E, N> 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<E, N> incidentEdgeMap = |
| Maps.asMap(network.incidentEdges(node), adjacentNodeFn(network, node)); |
| return network.allowsParallelEdges() |
| ? UndirectedMultiNetworkConnections.ofImmutable(incidentEdgeMap) |
| : UndirectedNetworkConnections.ofImmutable(incidentEdgeMap); |
| } |
| } |
| |
| private static <N, E> Function<E, N> sourceNodeFn(final Network<N, E> network) { |
| return new Function<E, N>() { |
| @Override |
| public N apply(E edge) { |
| return network.incidentNodes(edge).source(); |
| } |
| }; |
| } |
| |
| private static <N, E> Function<E, N> targetNodeFn(final Network<N, E> network) { |
| return new Function<E, N>() { |
| @Override |
| public N apply(E edge) { |
| return network.incidentNodes(edge).target(); |
| } |
| }; |
| } |
| |
| private static <N, E> Function<E, N> adjacentNodeFn(final Network<N, E> network, final N node) { |
| return new Function<E, N>() { |
| @Override |
| public N apply(E edge) { |
| return network.incidentNodes(edge).adjacentNode(node); |
| } |
| }; |
| } |
| |
| /** |
| * A builder for creating {@link ImmutableNetwork} instances, especially {@code static final} |
| * networks. Example: |
| * |
| * <pre>{@code |
| * static final ImmutableNetwork<City, Train> TRAIN_NETWORK = |
| * NetworkBuilder.undirected() |
| * .allowsParallelEdges(true) |
| * .<City, Train>immutable() |
| * .addEdge(PARIS, BRUSSELS, Thalys.trainNumber("1111")) |
| * .addEdge(PARIS, BRUSSELS, RegionalTrain.trainNumber("2222")) |
| * .addEdge(LONDON, PARIS, Eurostar.trainNumber("3333")) |
| * .addEdge(LONDON, BRUSSELS, Eurostar.trainNumber("4444")) |
| * .addNode(REYKJAVIK) |
| * .build(); |
| * }</pre> |
| * |
| * <p>Builder instances can be reused; it is safe to call {@link #build} multiple times to build |
| * multiple networks in series. Each new network contains all the elements of the ones created |
| * before it. |
| * |
| * @since 28.0 |
| */ |
| public static class Builder<N, E> { |
| |
| private final MutableNetwork<N, E> mutableNetwork; |
| |
| Builder(NetworkBuilder<N, E> networkBuilder) { |
| this.mutableNetwork = networkBuilder.build(); |
| } |
| |
| /** |
| * Adds {@code node} if it is not already present. |
| * |
| * <p><b>Nodes must be unique</b>, just as {@code Map} keys must be. They must also be non-null. |
| * |
| * @return this {@code Builder} object |
| */ |
| @CanIgnoreReturnValue |
| public ImmutableNetwork.Builder<N, E> addNode(N node) { |
| mutableNetwork.addNode(node); |
| return this; |
| } |
| |
| /** |
| * Adds {@code edge} connecting {@code nodeU} to {@code nodeV}. |
| * |
| * <p>If the network is directed, {@code edge} will be directed in this network; otherwise, it |
| * will be undirected. |
| * |
| * <p><b>{@code edge} must be unique to this network</b>, just as a {@code Map} key must be. It |
| * must also be non-null. |
| * |
| * <p>If {@code nodeU} and {@code nodeV} are not already present in this network, this method |
| * will silently {@link #addNode(Object) add} {@code nodeU} and {@code nodeV} to the network. |
| * |
| * <p>If {@code edge} already connects {@code nodeU} to {@code nodeV} (in the specified order if |
| * this network {@link #isDirected()}, else in any order), then this method will have no effect. |
| * |
| * @return this {@code Builder} object |
| * @throws IllegalArgumentException if {@code edge} already exists in the network and does not |
| * connect {@code nodeU} to {@code nodeV} |
| * @throws IllegalArgumentException if the introduction of the edge would violate {@link |
| * #allowsParallelEdges()} or {@link #allowsSelfLoops()} |
| */ |
| @CanIgnoreReturnValue |
| public ImmutableNetwork.Builder<N, E> addEdge(N nodeU, N nodeV, E edge) { |
| mutableNetwork.addEdge(nodeU, nodeV, edge); |
| return this; |
| } |
| |
| /** |
| * Adds {@code edge} connecting {@code endpoints}. In an undirected network, {@code edge} will |
| * also connect {@code nodeV} to {@code nodeU}. |
| * |
| * <p>If this network is directed, {@code edge} will be directed in this network; if it is |
| * undirected, {@code edge} will be undirected in this network. |
| * |
| * <p>If this network is directed, {@code endpoints} must be ordered. |
| * |
| * <p><b>{@code edge} must be unique to this network</b>, just as a {@code Map} key must be. It |
| * must also be non-null. |
| * |
| * <p>If either or both endpoints are not already present in this network, this method will |
| * silently {@link #addNode(Object) add} each missing endpoint to the network. |
| * |
| * <p>If {@code edge} already connects an endpoint pair equal to {@code endpoints}, then this |
| * method will have no effect. |
| * |
| * @return this {@code Builder} object |
| * @throws IllegalArgumentException if {@code edge} already exists in the network and connects |
| * some other endpoint pair that is not equal to {@code endpoints} |
| * @throws IllegalArgumentException if the introduction of the edge would violate {@link |
| * #allowsParallelEdges()} or {@link #allowsSelfLoops()} |
| * @throws IllegalArgumentException if the endpoints are unordered and the network is directed |
| */ |
| @CanIgnoreReturnValue |
| public ImmutableNetwork.Builder<N, E> addEdge(EndpointPair<N> endpoints, E edge) { |
| mutableNetwork.addEdge(endpoints, edge); |
| return this; |
| } |
| |
| /** |
| * Returns a newly-created {@code ImmutableNetwork} based on the contents of this {@code |
| * Builder}. |
| */ |
| public ImmutableNetwork<N, E> build() { |
| return ImmutableNetwork.copyOf(mutableNetwork); |
| } |
| } |
| } |