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.checkNotNull; 020import static com.google.common.graph.Graphs.checkNonNegative; 021 022import com.google.common.annotations.Beta; 023import com.google.common.base.Optional; 024 025/** 026 * A builder for constructing instances of {@link MutableNetwork} or {@link ImmutableNetwork} with 027 * user-defined properties. 028 * 029 * <p>A network built by this class will have the following properties by default: 030 * 031 * <ul> 032 * <li>does not allow parallel edges 033 * <li>does not allow self-loops 034 * <li>orders {@link Network#nodes()} and {@link Network#edges()} in the order in which the 035 * elements were added 036 * </ul> 037 * 038 * <p>Examples of use: 039 * 040 * <pre>{@code 041 * // Building a mutable network 042 * MutableNetwork<String, Integer> network = 043 * NetworkBuilder.directed().allowsParallelEdges(true).build(); 044 * flightNetwork.addEdge("LAX", "ATL", 3025); 045 * flightNetwork.addEdge("LAX", "ATL", 1598); 046 * flightNetwork.addEdge("ATL", "LAX", 2450); 047 * 048 * // Building a immutable network 049 * ImmutableNetwork<String, Integer> immutableNetwork = 050 * NetworkBuilder.directed() 051 * .allowsParallelEdges(true) 052 * .<String, Integer>immutable() 053 * .addEdge("LAX", "ATL", 3025) 054 * .addEdge("LAX", "ATL", 1598) 055 * .addEdge("ATL", "LAX", 2450) 056 * .build(); 057 * }</pre> 058 * 059 * @author James Sexton 060 * @author Joshua O'Madadhain 061 * @param <N> The most general node type this builder will support. This is normally {@code Object} 062 * unless it is constrained by using a method like {@link #nodeOrder}, or the builder is 063 * constructed based on an existing {@code Network} using {@link #from(Network)}. 064 * @param <E> The most general edge type this builder will support. This is normally {@code Object} 065 * unless it is constrained by using a method like {@link #edgeOrder}, or the builder is 066 * constructed based on an existing {@code Network} using {@link #from(Network)}. 067 * @since 20.0 068 */ 069@Beta 070@ElementTypesAreNonnullByDefault 071public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> { 072 boolean allowsParallelEdges = false; 073 ElementOrder<? super E> edgeOrder = ElementOrder.insertion(); 074 Optional<Integer> expectedEdgeCount = Optional.absent(); 075 076 /** Creates a new instance with the specified edge directionality. */ 077 private NetworkBuilder(boolean directed) { 078 super(directed); 079 } 080 081 /** Returns a {@link NetworkBuilder} for building directed networks. */ 082 public static NetworkBuilder<Object, Object> directed() { 083 return new NetworkBuilder<>(true); 084 } 085 086 /** Returns a {@link NetworkBuilder} for building undirected networks. */ 087 public static NetworkBuilder<Object, Object> undirected() { 088 return new NetworkBuilder<>(false); 089 } 090 091 /** 092 * Returns a {@link NetworkBuilder} initialized with all properties queryable from {@code 093 * network}. 094 * 095 * <p>The "queryable" properties are those that are exposed through the {@link Network} interface, 096 * such as {@link Network#isDirected()}. Other properties, such as {@link 097 * #expectedNodeCount(int)}, are not set in the new builder. 098 */ 099 public static <N, E> NetworkBuilder<N, E> from(Network<N, E> network) { 100 return new NetworkBuilder<N, E>(network.isDirected()) 101 .allowsParallelEdges(network.allowsParallelEdges()) 102 .allowsSelfLoops(network.allowsSelfLoops()) 103 .nodeOrder(network.nodeOrder()) 104 .edgeOrder(network.edgeOrder()); 105 } 106 107 /** 108 * Returns an {@link ImmutableNetwork.Builder} with the properties of this {@link NetworkBuilder}. 109 * 110 * <p>The returned builder can be used for populating an {@link ImmutableNetwork}. 111 * 112 * @since 28.0 113 */ 114 public <N1 extends N, E1 extends E> ImmutableNetwork.Builder<N1, E1> immutable() { 115 NetworkBuilder<N1, E1> castBuilder = cast(); 116 return new ImmutableNetwork.Builder<>(castBuilder); 117 } 118 119 /** 120 * Specifies whether the network will allow parallel edges. Attempting to add a parallel edge to a 121 * network that does not allow them will throw an {@link UnsupportedOperationException}. 122 * 123 * <p>The default value is {@code false}. 124 */ 125 public NetworkBuilder<N, E> allowsParallelEdges(boolean allowsParallelEdges) { 126 this.allowsParallelEdges = allowsParallelEdges; 127 return this; 128 } 129 130 /** 131 * Specifies whether the network will allow self-loops (edges that connect a node to itself). 132 * Attempting to add a self-loop to a network that does not allow them will throw an {@link 133 * UnsupportedOperationException}. 134 * 135 * <p>The default value is {@code false}. 136 */ 137 public NetworkBuilder<N, E> allowsSelfLoops(boolean allowsSelfLoops) { 138 this.allowsSelfLoops = allowsSelfLoops; 139 return this; 140 } 141 142 /** 143 * Specifies the expected number of nodes in the network. 144 * 145 * @throws IllegalArgumentException if {@code expectedNodeCount} is negative 146 */ 147 public NetworkBuilder<N, E> expectedNodeCount(int expectedNodeCount) { 148 this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount)); 149 return this; 150 } 151 152 /** 153 * Specifies the expected number of edges in the network. 154 * 155 * @throws IllegalArgumentException if {@code expectedEdgeCount} is negative 156 */ 157 public NetworkBuilder<N, E> expectedEdgeCount(int expectedEdgeCount) { 158 this.expectedEdgeCount = Optional.of(checkNonNegative(expectedEdgeCount)); 159 return this; 160 } 161 162 /** 163 * Specifies the order of iteration for the elements of {@link Network#nodes()}. 164 * 165 * <p>The default value is {@link ElementOrder#insertion() insertion order}. 166 */ 167 public <N1 extends N> NetworkBuilder<N1, E> nodeOrder(ElementOrder<N1> nodeOrder) { 168 NetworkBuilder<N1, E> newBuilder = cast(); 169 newBuilder.nodeOrder = checkNotNull(nodeOrder); 170 return newBuilder; 171 } 172 173 /** 174 * Specifies the order of iteration for the elements of {@link Network#edges()}. 175 * 176 * <p>The default value is {@link ElementOrder#insertion() insertion order}. 177 */ 178 public <E1 extends E> NetworkBuilder<N, E1> edgeOrder(ElementOrder<E1> edgeOrder) { 179 NetworkBuilder<N, E1> newBuilder = cast(); 180 newBuilder.edgeOrder = checkNotNull(edgeOrder); 181 return newBuilder; 182 } 183 184 /** Returns an empty {@link MutableNetwork} with the properties of this {@link NetworkBuilder}. */ 185 public <N1 extends N, E1 extends E> MutableNetwork<N1, E1> build() { 186 return new StandardMutableNetwork<>(this); 187 } 188 189 @SuppressWarnings("unchecked") 190 private <N1 extends N, E1 extends E> NetworkBuilder<N1, E1> cast() { 191 return (NetworkBuilder<N1, E1>) this; 192 } 193}