001/* 002 * Copyright (C) 2016 The Guava Authors 003 * 004 * Licensed under the Apache License, Version 2.0 (the "License"); 005 * you may not use this file except in compliance with the License. 006 * You may obtain a copy of the License at 007 * 008 * http://www.apache.org/licenses/LICENSE-2.0 009 * 010 * Unless required by applicable law or agreed to in writing, software 011 * distributed under the License is distributed on an "AS IS" BASIS, 012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 013 * See the License for the specific language governing permissions and 014 * limitations under the License. 015 */ 016 017package com.google.common.graph; 018 019import static com.google.common.base.Preconditions.checkArgument; 020import static com.google.common.base.Preconditions.checkNotNull; 021import static com.google.common.graph.Graphs.checkNonNegative; 022 023import com.google.common.annotations.Beta; 024import com.google.common.base.Optional; 025import com.google.errorprone.annotations.CanIgnoreReturnValue; 026 027/** 028 * A builder for constructing instances of {@link MutableValueGraph} or {@link ImmutableValueGraph} 029 * with user-defined properties. 030 * 031 * <p>A {@code ValueGraph} built by this class has the following default properties: 032 * 033 * <ul> 034 * <li>does not allow self-loops 035 * <li>orders {@link ValueGraph#nodes()} in the order in which the elements were added (insertion 036 * order) 037 * </ul> 038 * 039 * <p>{@code ValueGraph}s built by this class also guarantee that each collection-returning accessor 040 * returns a <b>(live) unmodifiable view</b>; see <a 041 * href="https://github.com/google/guava/wiki/GraphsExplained#accessor-behavior">the external 042 * documentation</a> for details. 043 * 044 * <p>Examples of use: 045 * 046 * <pre>{@code 047 * // Building a mutable value graph 048 * MutableValueGraph<String, Double> graph = 049 * ValueGraphBuilder.undirected().allowsSelfLoops(true).build(); 050 * graph.putEdgeValue("San Francisco", "San Francisco", 0.0); 051 * graph.putEdgeValue("San Jose", "San Jose", 0.0); 052 * graph.putEdgeValue("San Francisco", "San Jose", 48.4); 053 * 054 * // Building an immutable value graph 055 * ImmutableValueGraph<String, Double> immutableGraph = 056 * ValueGraphBuilder.undirected() 057 * .allowsSelfLoops(true) 058 * .<String, Double>immutable() 059 * .putEdgeValue("San Francisco", "San Francisco", 0.0) 060 * .putEdgeValue("San Jose", "San Jose", 0.0) 061 * .putEdgeValue("San Francisco", "San Jose", 48.4) 062 * .build(); 063 * }</pre> 064 * 065 * @author James Sexton 066 * @author Joshua O'Madadhain 067 * @param <N> The most general node type this builder will support. This is normally {@code Object} 068 * unless it is constrained by using a method like {@link #nodeOrder}, or the builder is 069 * constructed based on an existing {@code ValueGraph} using {@link #from(ValueGraph)}. 070 * @param <V> The most general value type this builder will support. This is normally {@code Object} 071 * unless the builder is constructed based on an existing {@code Graph} using {@link 072 * #from(ValueGraph)}. 073 * @since 20.0 074 */ 075@Beta 076@ElementTypesAreNonnullByDefault 077public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> { 078 079 /** Creates a new instance with the specified edge directionality. */ 080 private ValueGraphBuilder(boolean directed) { 081 super(directed); 082 } 083 084 /** Returns a {@link ValueGraphBuilder} for building directed graphs. */ 085 public static ValueGraphBuilder<Object, Object> directed() { 086 return new ValueGraphBuilder<>(true); 087 } 088 089 /** Returns a {@link ValueGraphBuilder} for building undirected graphs. */ 090 public static ValueGraphBuilder<Object, Object> undirected() { 091 return new ValueGraphBuilder<>(false); 092 } 093 094 /** 095 * Returns a {@link ValueGraphBuilder} initialized with all properties queryable from {@code 096 * graph}. 097 * 098 * <p>The "queryable" properties are those that are exposed through the {@link ValueGraph} 099 * interface, such as {@link ValueGraph#isDirected()}. Other properties, such as {@link 100 * #expectedNodeCount(int)}, are not set in the new builder. 101 */ 102 public static <N, V> ValueGraphBuilder<N, V> from(ValueGraph<N, V> graph) { 103 return new ValueGraphBuilder<N, V>(graph.isDirected()) 104 .allowsSelfLoops(graph.allowsSelfLoops()) 105 .nodeOrder(graph.nodeOrder()) 106 .incidentEdgeOrder(graph.incidentEdgeOrder()); 107 } 108 109 /** 110 * Returns an {@link ImmutableValueGraph.Builder} with the properties of this {@link 111 * ValueGraphBuilder}. 112 * 113 * <p>The returned builder can be used for populating an {@link ImmutableValueGraph}. 114 * 115 * <p>Note that the returned builder will always have {@link #incidentEdgeOrder} set to {@link 116 * ElementOrder#stable()}, regardless of the value that was set in this builder. 117 * 118 * @since 28.0 119 */ 120 public <N1 extends N, V1 extends V> ImmutableValueGraph.Builder<N1, V1> immutable() { 121 ValueGraphBuilder<N1, V1> castBuilder = cast(); 122 return new ImmutableValueGraph.Builder<>(castBuilder); 123 } 124 125 /** 126 * Specifies whether the graph will allow self-loops (edges that connect a node to itself). 127 * Attempting to add a self-loop to a graph that does not allow them will throw an {@link 128 * UnsupportedOperationException}. 129 * 130 * <p>The default value is {@code false}. 131 */ 132 @CanIgnoreReturnValue 133 public ValueGraphBuilder<N, V> allowsSelfLoops(boolean allowsSelfLoops) { 134 this.allowsSelfLoops = allowsSelfLoops; 135 return this; 136 } 137 138 /** 139 * Specifies the expected number of nodes in the graph. 140 * 141 * @throws IllegalArgumentException if {@code expectedNodeCount} is negative 142 */ 143 @CanIgnoreReturnValue 144 public ValueGraphBuilder<N, V> expectedNodeCount(int expectedNodeCount) { 145 this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount)); 146 return this; 147 } 148 149 /** 150 * Specifies the order of iteration for the elements of {@link Graph#nodes()}. 151 * 152 * <p>The default value is {@link ElementOrder#insertion() insertion order}. 153 */ 154 public <N1 extends N> ValueGraphBuilder<N1, V> nodeOrder(ElementOrder<N1> nodeOrder) { 155 ValueGraphBuilder<N1, V> newBuilder = cast(); 156 newBuilder.nodeOrder = checkNotNull(nodeOrder); 157 return newBuilder; 158 } 159 160 /** 161 * Specifies the order of iteration for the elements of {@link ValueGraph#edges()}, {@link 162 * ValueGraph#adjacentNodes(Object)}, {@link ValueGraph#predecessors(Object)}, {@link 163 * ValueGraph#successors(Object)} and {@link ValueGraph#incidentEdges(Object)}. 164 * 165 * <p>The default value is {@link ElementOrder#unordered() unordered} for mutable graphs. For 166 * immutable graphs, this value is ignored; they always have a {@link ElementOrder#stable() 167 * stable} order. 168 * 169 * @throws IllegalArgumentException if {@code incidentEdgeOrder} is not either {@code 170 * ElementOrder.unordered()} or {@code ElementOrder.stable()}. 171 * @since 29.0 172 */ 173 public <N1 extends N> ValueGraphBuilder<N1, V> incidentEdgeOrder( 174 ElementOrder<N1> incidentEdgeOrder) { 175 checkArgument( 176 incidentEdgeOrder.type() == ElementOrder.Type.UNORDERED 177 || incidentEdgeOrder.type() == ElementOrder.Type.STABLE, 178 "The given elementOrder (%s) is unsupported. incidentEdgeOrder() only supports" 179 + " ElementOrder.unordered() and ElementOrder.stable().", 180 incidentEdgeOrder); 181 ValueGraphBuilder<N1, V> newBuilder = cast(); 182 newBuilder.incidentEdgeOrder = checkNotNull(incidentEdgeOrder); 183 return newBuilder; 184 } 185 /** 186 * Returns an empty {@link MutableValueGraph} with the properties of this {@link 187 * ValueGraphBuilder}. 188 */ 189 public <N1 extends N, V1 extends V> MutableValueGraph<N1, V1> build() { 190 return new StandardMutableValueGraph<>(this); 191 } 192 193 ValueGraphBuilder<N, V> copy() { 194 ValueGraphBuilder<N, V> newBuilder = new ValueGraphBuilder<>(directed); 195 newBuilder.allowsSelfLoops = allowsSelfLoops; 196 newBuilder.nodeOrder = nodeOrder; 197 newBuilder.expectedNodeCount = expectedNodeCount; 198 newBuilder.incidentEdgeOrder = incidentEdgeOrder; 199 return newBuilder; 200 } 201 202 @SuppressWarnings("unchecked") 203 private <N1 extends N, V1 extends V> ValueGraphBuilder<N1, V1> cast() { 204 return (ValueGraphBuilder<N1, V1>) this; 205 } 206}