| /* |
| * Copyright (C) 2016 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.checkState; |
| import static com.google.common.graph.GraphConstants.INNER_CAPACITY; |
| import static com.google.common.graph.GraphConstants.INNER_LOAD_FACTOR; |
| |
| import com.google.common.collect.HashMultiset; |
| import com.google.common.collect.ImmutableMap; |
| import com.google.common.collect.Multiset; |
| import com.google.errorprone.annotations.concurrent.LazyInit; |
| import java.lang.ref.Reference; |
| import java.lang.ref.SoftReference; |
| import java.util.Collections; |
| import java.util.HashMap; |
| import java.util.Map; |
| import java.util.Set; |
| import org.checkerframework.checker.nullness.compatqual.NullableDecl; |
| |
| /** |
| * An implementation of {@link NetworkConnections} for undirected networks with parallel edges. |
| * |
| * @author James Sexton |
| * @param <N> Node parameter type |
| * @param <E> Edge parameter type |
| */ |
| final class UndirectedMultiNetworkConnections<N, E> |
| extends AbstractUndirectedNetworkConnections<N, E> { |
| |
| private UndirectedMultiNetworkConnections(Map<E, N> incidentEdges) { |
| super(incidentEdges); |
| } |
| |
| static <N, E> UndirectedMultiNetworkConnections<N, E> of() { |
| return new UndirectedMultiNetworkConnections<>( |
| new HashMap<E, N>(INNER_CAPACITY, INNER_LOAD_FACTOR)); |
| } |
| |
| static <N, E> UndirectedMultiNetworkConnections<N, E> ofImmutable(Map<E, N> incidentEdges) { |
| return new UndirectedMultiNetworkConnections<>(ImmutableMap.copyOf(incidentEdges)); |
| } |
| |
| @LazyInit private transient Reference<Multiset<N>> adjacentNodesReference; |
| |
| @Override |
| public Set<N> adjacentNodes() { |
| return Collections.unmodifiableSet(adjacentNodesMultiset().elementSet()); |
| } |
| |
| private Multiset<N> adjacentNodesMultiset() { |
| Multiset<N> adjacentNodes = getReference(adjacentNodesReference); |
| if (adjacentNodes == null) { |
| adjacentNodes = HashMultiset.create(incidentEdgeMap.values()); |
| adjacentNodesReference = new SoftReference<>(adjacentNodes); |
| } |
| return adjacentNodes; |
| } |
| |
| @Override |
| public Set<E> edgesConnecting(final N node) { |
| return new MultiEdgesConnecting<E>(incidentEdgeMap, node) { |
| @Override |
| public int size() { |
| return adjacentNodesMultiset().count(node); |
| } |
| }; |
| } |
| |
| @Override |
| public N removeInEdge(E edge, boolean isSelfLoop) { |
| if (!isSelfLoop) { |
| return removeOutEdge(edge); |
| } |
| return null; |
| } |
| |
| @Override |
| public N removeOutEdge(E edge) { |
| N node = super.removeOutEdge(edge); |
| Multiset<N> adjacentNodes = getReference(adjacentNodesReference); |
| if (adjacentNodes != null) { |
| checkState(adjacentNodes.remove(node)); |
| } |
| return node; |
| } |
| |
| @Override |
| public void addInEdge(E edge, N node, boolean isSelfLoop) { |
| if (!isSelfLoop) { |
| addOutEdge(edge, node); |
| } |
| } |
| |
| @Override |
| public void addOutEdge(E edge, N node) { |
| super.addOutEdge(edge, node); |
| Multiset<N> adjacentNodes = getReference(adjacentNodesReference); |
| if (adjacentNodes != null) { |
| checkState(adjacentNodes.add(node)); |
| } |
| } |
| |
| @NullableDecl |
| private static <T> T getReference(@NullableDecl Reference<T> reference) { |
| return (reference == null) ? null : reference.get(); |
| } |
| } |