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 com.google.common.base.Preconditions.checkArgument;
20 import static com.google.common.base.Preconditions.checkNotNull;
21 import static com.google.common.graph.Graphs.checkNonNegative;
22
23 import com.google.common.annotations.Beta;
24 import com.google.common.base.Optional;
25
26 /**
27 * A builder for constructing instances of {@link MutableValueGraph} or {@link ImmutableValueGraph}
28 * with user-defined properties.
29 *
30 * <p>A graph built by this class will have the following properties by default:
31 *
32 * <ul>
33 * <li>does not allow self-loops
34 * <li>orders {@link Graph#nodes()} in the order in which the elements were added
35 * </ul>
36 *
37 * <p>Examples of use:
38 *
39 * <pre>{@code
40 * // Building a mutable value graph
41 * MutableValueGraph<String, Double> graph =
42 * ValueGraphBuilder.undirected().allowsSelfLoops(true).build();
43 * graph.putEdgeValue("San Francisco", "San Francisco", 0.0);
44 * graph.putEdgeValue("San Jose", "San Jose", 0.0);
45 * graph.putEdgeValue("San Francisco", "San Jose", 48.4);
46 *
47 * // Building an immutable value graph
48 * ImmutableValueGraph<String, Double> immutableGraph =
49 * ValueGraphBuilder.undirected()
50 * .allowsSelfLoops(true)
51 * .<String, Double>immutable()
52 * .putEdgeValue("San Francisco", "San Francisco", 0.0)
53 * .putEdgeValue("San Jose", "San Jose", 0.0)
54 * .putEdgeValue("San Francisco", "San Jose", 48.4)
55 * .build();
56 * }</pre>
57 *
58 * @author James Sexton
59 * @author Joshua O'Madadhain
60 * @param <N> The most general node type this builder will support. This is normally {@code Object}
61 * unless it is constrained by using a method like {@link #nodeOrder}, or the builder is
62 * constructed based on an existing {@code ValueGraph} using {@link #from(ValueGraph)}.
63 * @param <V> The most general value type this builder will support. This is normally {@code Object}
64 * unless the builder is constructed based on an existing {@code Graph} using {@link
65 * #from(ValueGraph)}.
66 * @since 20.0
67 */
68 @Beta
69 @ElementTypesAreNonnullByDefault
70 public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> {
71
72 /** Creates a new instance with the specified edge directionality. */
73 private ValueGraphBuilder(boolean directed) {
74 super(directed);
75 }
76
77 /** Returns a {@link ValueGraphBuilder} for building directed graphs. */
78 public static ValueGraphBuilder<Object, Object> directed() {
79 return new ValueGraphBuilder<>(true);
80 }
81
82 /** Returns a {@link ValueGraphBuilder} for building undirected graphs. */
83 public static ValueGraphBuilder<Object, Object> undirected() {
84 return new ValueGraphBuilder<>(false);
85 }
86
87 /**
88 * Returns a {@link ValueGraphBuilder} initialized with all properties queryable from {@code
89 * graph}.
90 *
91 * <p>The "queryable" properties are those that are exposed through the {@link ValueGraph}
92 * interface, such as {@link ValueGraph#isDirected()}. Other properties, such as {@link
93 * #expectedNodeCount(int)}, are not set in the new builder.
94 */
95 public static <N, V> ValueGraphBuilder<N, V> from(ValueGraph<N, V> graph) {
96 return new ValueGraphBuilder<N, V>(graph.isDirected())
97 .allowsSelfLoops(graph.allowsSelfLoops())
98 .nodeOrder(graph.nodeOrder())
99 .incidentEdgeOrder(graph.incidentEdgeOrder());
100 }
101
102 /**
103 * Returns an {@link ImmutableValueGraph.Builder} with the properties of this {@link
104 * ValueGraphBuilder}.
105 *
106 * <p>The returned builder can be used for populating an {@link ImmutableValueGraph}.
107 *
108 * <p>Note that the returned builder will always have {@link #incidentEdgeOrder} set to {@link
109 * ElementOrder#stable()}, regardless of the value that was set in this builder.
110 *
111 * @since 28.0
112 */
113 public <N1 extends N, V1 extends V> ImmutableValueGraph.Builder<N1, V1> immutable() {
114 ValueGraphBuilder<N1, V1> castBuilder = cast();
115 return new ImmutableValueGraph.Builder<>(castBuilder);
116 }
117
118 /**
119 * Specifies whether the graph will allow self-loops (edges that connect a node to itself).
120 * Attempting to add a self-loop to a graph that does not allow them will throw an {@link
121 * UnsupportedOperationException}.
122 *
123 * <p>The default value is {@code false}.
124 */
125 public ValueGraphBuilder<N, V> allowsSelfLoops(boolean allowsSelfLoops) {
126 this.allowsSelfLoops = allowsSelfLoops;
127 return this;
128 }
129
130 /**
131 * Specifies the expected number of nodes in the graph.
132 *
133 * @throws IllegalArgumentException if {@code expectedNodeCount} is negative
134 */
135 public ValueGraphBuilder<N, V> expectedNodeCount(int expectedNodeCount) {
136 this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount));
137 return this;
138 }
139
140 /**
141 * Specifies the order of iteration for the elements of {@link Graph#nodes()}.
142 *
143 * <p>The default value is {@link ElementOrder#insertion() insertion order}.
144 */
145 public <N1 extends N> ValueGraphBuilder<N1, V> nodeOrder(ElementOrder<N1> nodeOrder) {
146 ValueGraphBuilder<N1, V> newBuilder = cast();
147 newBuilder.nodeOrder = checkNotNull(nodeOrder);
148 return newBuilder;
149 }
150
151 /**
152 * Specifies the order of iteration for the elements of {@link ValueGraph#edges()}, {@link
153 * ValueGraph#adjacentNodes(Object)}, {@link ValueGraph#predecessors(Object)}, {@link
154 * ValueGraph#successors(Object)} and {@link ValueGraph#incidentEdges(Object)}.
155 *
156 * <p>The default value is {@link ElementOrder#unordered() unordered} for mutable graphs. For
157 * immutable graphs, this value is ignored; they always have a {@link ElementOrder#stable()
158 * stable} order.
159 *
160 * @throws IllegalArgumentException if {@code incidentEdgeOrder} is not either {@code
161 * ElementOrder.unordered()} or {@code ElementOrder.stable()}.
162 * @since 29.0
163 */
164 public <N1 extends N> ValueGraphBuilder<N1, V> incidentEdgeOrder(
165 ElementOrder<N1> incidentEdgeOrder) {
166 checkArgument(
167 incidentEdgeOrder.type() == ElementOrder.Type.UNORDERED
168 || incidentEdgeOrder.type() == ElementOrder.Type.STABLE,
169 "The given elementOrder (%s) is unsupported. incidentEdgeOrder() only supports"
170 + " ElementOrder.unordered() and ElementOrder.stable().",
171 incidentEdgeOrder);
172 ValueGraphBuilder<N1, V> newBuilder = cast();
173 newBuilder.incidentEdgeOrder = checkNotNull(incidentEdgeOrder);
174 return newBuilder;
175 }
176 /**
177 * Returns an empty {@link MutableValueGraph} with the properties of this {@link
178 * ValueGraphBuilder}.
179 */
180 public <N1 extends N, V1 extends V> MutableValueGraph<N1, V1> build() {
181 return new StandardMutableValueGraph<>(this);
182 }
183
184 ValueGraphBuilder<N, V> copy() {
185 ValueGraphBuilder<N, V> newBuilder = new ValueGraphBuilder<>(directed);
186 newBuilder.allowsSelfLoops = allowsSelfLoops;
187 newBuilder.nodeOrder = nodeOrder;
188 newBuilder.expectedNodeCount = expectedNodeCount;
189 newBuilder.incidentEdgeOrder = incidentEdgeOrder;
190 return newBuilder;
191 }
192
193 @SuppressWarnings("unchecked")
194 private <N1 extends N, V1 extends V> ValueGraphBuilder<N1, V1> cast() {
195 return (ValueGraphBuilder<N1, V1>) this;
196 }
197 }