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/*
 * 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); } }; } }





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