| /* |
| * 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 directed networks with parallel edges. |
| * |
| * @author James Sexton |
| * @param <N> Node parameter type |
| * @param <E> Edge parameter type |
| */ |
| final class DirectedMultiNetworkConnections<N, E> extends AbstractDirectedNetworkConnections<N, E> { |
| |
| private DirectedMultiNetworkConnections( |
| Map<E, N> inEdges, Map<E, N> outEdges, int selfLoopCount) { |
| super(inEdges, outEdges, selfLoopCount); |
| } |
| |
| static <N, E> DirectedMultiNetworkConnections<N, E> of() { |
| return new DirectedMultiNetworkConnections<>( |
| new HashMap<E, N>(INNER_CAPACITY, INNER_LOAD_FACTOR), |
| new HashMap<E, N>(INNER_CAPACITY, INNER_LOAD_FACTOR), |
| 0); |
| } |
| |
| static <N, E> DirectedMultiNetworkConnections<N, E> ofImmutable( |
| Map<E, N> inEdges, Map<E, N> outEdges, int selfLoopCount) { |
| return new DirectedMultiNetworkConnections<>( |
| ImmutableMap.copyOf(inEdges), ImmutableMap.copyOf(outEdges), selfLoopCount); |
| } |
| |
| @LazyInit private transient Reference<Multiset<N>> predecessorsReference; |
| |
| @Override |
| public Set<N> predecessors() { |
| return Collections.unmodifiableSet(predecessorsMultiset().elementSet()); |
| } |
| |
| private Multiset<N> predecessorsMultiset() { |
| Multiset<N> predecessors = getReference(predecessorsReference); |
| if (predecessors == null) { |
| predecessors = HashMultiset.create(inEdgeMap.values()); |
| predecessorsReference = new SoftReference<>(predecessors); |
| } |
| return predecessors; |
| } |
| |
| @LazyInit private transient Reference<Multiset<N>> successorsReference; |
| |
| @Override |
| public Set<N> successors() { |
| return Collections.unmodifiableSet(successorsMultiset().elementSet()); |
| } |
| |
| private Multiset<N> successorsMultiset() { |
| Multiset<N> successors = getReference(successorsReference); |
| if (successors == null) { |
| successors = HashMultiset.create(outEdgeMap.values()); |
| successorsReference = new SoftReference<>(successors); |
| } |
| return successors; |
| } |
| |
| @Override |
| public Set<E> edgesConnecting(final N node) { |
| return new MultiEdgesConnecting<E>(outEdgeMap, node) { |
| @Override |
| public int size() { |
| return successorsMultiset().count(node); |
| } |
| }; |
| } |
| |
| @Override |
| public N removeInEdge(E edge, boolean isSelfLoop) { |
| N node = super.removeInEdge(edge, isSelfLoop); |
| Multiset<N> predecessors = getReference(predecessorsReference); |
| if (predecessors != null) { |
| checkState(predecessors.remove(node)); |
| } |
| return node; |
| } |
| |
| @Override |
| public N removeOutEdge(E edge) { |
| N node = super.removeOutEdge(edge); |
| Multiset<N> successors = getReference(successorsReference); |
| if (successors != null) { |
| checkState(successors.remove(node)); |
| } |
| return node; |
| } |
| |
| @Override |
| public void addInEdge(E edge, N node, boolean isSelfLoop) { |
| super.addInEdge(edge, node, isSelfLoop); |
| Multiset<N> predecessors = getReference(predecessorsReference); |
| if (predecessors != null) { |
| checkState(predecessors.add(node)); |
| } |
| } |
| |
| @Override |
| public void addOutEdge(E edge, N node) { |
| super.addOutEdge(edge, node); |
| Multiset<N> successors = getReference(successorsReference); |
| if (successors != null) { |
| checkState(successors.add(node)); |
| } |
| } |
| |
| @NullableDecl |
| private static <T> T getReference(@NullableDecl Reference<T> reference) { |
| return (reference == null) ? null : reference.get(); |
| } |
| } |