1 /*
2 * Copyright (C) 2016 The Guava Authors
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17 package com.google.common.graph;
18
19 import static java.util.Objects.requireNonNull;
20
21 import com.google.common.annotations.Beta;
22 import com.google.common.base.Function;
23 import com.google.common.collect.Maps;
24 import java.util.Map;
25 import java.util.Optional;
26 import java.util.Set;
27 import javax.annotation.CheckForNull;
28
29 /**
30 * This class provides a skeletal implementation of {@link ValueGraph}. It is recommended to extend
31 * this class rather than implement {@link ValueGraph} directly.
32 *
33 * <p>The methods implemented in this class should not be overridden unless the subclass admits a
34 * more efficient implementation.
35 *
36 * @author James Sexton
37 * @param <N> Node parameter type
38 * @param <V> Value parameter type
39 * @since 20.0
40 */
41 @Beta
42 @ElementTypesAreNonnullByDefault
43 public abstract class AbstractValueGraph<N, V> extends AbstractBaseGraph<N>
44 implements ValueGraph<N, V> {
45
46 @Override
47 public Graph<N> asGraph() {
48 return new AbstractGraph<N>() {
49 @Override
50 public Set<N> nodes() {
51 return AbstractValueGraph.this.nodes();
52 }
53
54 @Override
55 public Set<EndpointPair<N>> edges() {
56 return AbstractValueGraph.this.edges();
57 }
58
59 @Override
60 public boolean isDirected() {
61 return AbstractValueGraph.this.isDirected();
62 }
63
64 @Override
65 public boolean allowsSelfLoops() {
66 return AbstractValueGraph.this.allowsSelfLoops();
67 }
68
69 @Override
70 public ElementOrder<N> nodeOrder() {
71 return AbstractValueGraph.this.nodeOrder();
72 }
73
74 @Override
75 public ElementOrder<N> incidentEdgeOrder() {
76 return AbstractValueGraph.this.incidentEdgeOrder();
77 }
78
79 @Override
80 public Set<N> adjacentNodes(N node) {
81 return AbstractValueGraph.this.adjacentNodes(node);
82 }
83
84 @Override
85 public Set<N> predecessors(N node) {
86 return AbstractValueGraph.this.predecessors(node);
87 }
88
89 @Override
90 public Set<N> successors(N node) {
91 return AbstractValueGraph.this.successors(node);
92 }
93
94 @Override
95 public int degree(N node) {
96 return AbstractValueGraph.this.degree(node);
97 }
98
99 @Override
100 public int inDegree(N node) {
101 return AbstractValueGraph.this.inDegree(node);
102 }
103
104 @Override
105 public int outDegree(N node) {
106 return AbstractValueGraph.this.outDegree(node);
107 }
108 };
109 }
110
111 @Override
112 public Optional<V> edgeValue(N nodeU, N nodeV) {
113 return Optional.ofNullable(edgeValueOrDefault(nodeU, nodeV, null));
114 }
115
116 @Override
117 public Optional<V> edgeValue(EndpointPair<N> endpoints) {
118 return Optional.ofNullable(edgeValueOrDefault(endpoints, null));
119 }
120
121 @Override
122 public final boolean equals(@CheckForNull Object obj) {
123 if (obj == this) {
124 return true;
125 }
126 if (!(obj instanceof ValueGraph)) {
127 return false;
128 }
129 ValueGraph<?, ?> other = (ValueGraph<?, ?>) obj;
130
131 return isDirected() == other.isDirected()
132 && nodes().equals(other.nodes())
133 && edgeValueMap(this).equals(edgeValueMap(other));
134 }
135
136 @Override
137 public final int hashCode() {
138 return edgeValueMap(this).hashCode();
139 }
140
141 /** Returns a string representation of this graph. */
142 @Override
143 public String toString() {
144 return "isDirected: "
145 + isDirected()
146 + ", allowsSelfLoops: "
147 + allowsSelfLoops()
148 + ", nodes: "
149 + nodes()
150 + ", edges: "
151 + edgeValueMap(this);
152 }
153
154 private static <N, V> Map<EndpointPair<N>, V> edgeValueMap(final ValueGraph<N, V> graph) {
155 Function<EndpointPair<N>, V> edgeToValueFn =
156 new Function<EndpointPair<N>, V>() {
157 @Override
158 public V apply(EndpointPair<N> edge) {
159 // requireNonNull is safe because the endpoint pair comes from the graph.
160 return requireNonNull(graph.edgeValueOrDefault(edge.nodeU(), edge.nodeV(), null));
161 }
162 };
163 return Maps.asMap(graph.edges(), edgeToValueFn);
164 }
165 }