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 <N> 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 070public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> { 071 boolean allowsParallelEdges = false; 072 ElementOrder<? super E> edgeOrder = ElementOrder.insertion(); 073 Optional<Integer> expectedEdgeCount = Optional.absent(); 074 075 /** Creates a new instance with the specified edge directionality. */ 076 private NetworkBuilder(boolean directed) { 077 super(directed); 078 } 079 080 /** Returns a {@link NetworkBuilder} for building directed networks. */ 081 public static NetworkBuilder<Object, Object> directed() { 082 return new NetworkBuilder<>(true); 083 } 084 085 /** Returns a {@link NetworkBuilder} for building undirected networks. */ 086 public static NetworkBuilder<Object, Object> undirected() { 087 return new NetworkBuilder<>(false); 088 } 089 090 /** 091 * Returns a {@link NetworkBuilder} initialized with all properties queryable from {@code 092 * network}. 093 * 094 * <p>The "queryable" properties are those that are exposed through the {@link Network} interface, 095 * such as {@link Network#isDirected()}. Other properties, such as {@link 096 * #expectedNodeCount(int)}, are not set in the new builder. 097 */ 098 public static <N, E> NetworkBuilder<N, E> from(Network<N, E> network) { 099 return new NetworkBuilder<N, E>(network.isDirected()) 100 .allowsParallelEdges(network.allowsParallelEdges()) 101 .allowsSelfLoops(network.allowsSelfLoops()) 102 .nodeOrder(network.nodeOrder()) 103 .edgeOrder(network.edgeOrder()); 104 } 105 106 /** 107 * Returns an {@link ImmutableNetwork.Builder} with the properties of this {@link NetworkBuilder}. 108 * 109 * <p>The returned builder can be used for populating an {@link ImmutableNetwork}. 110 * 111 * @since 28.0 112 */ 113 public <N1 extends N, E1 extends E> ImmutableNetwork.Builder<N1, E1> immutable() { 114 NetworkBuilder<N1, E1> castBuilder = cast(); 115 return new ImmutableNetwork.Builder<>(castBuilder); 116 } 117 118 /** 119 * Specifies whether the network will allow parallel edges. Attempting to add a parallel edge to a 120 * network that does not allow them will throw an {@link UnsupportedOperationException}. 121 * 122 * <p>The default value is {@code false}. 123 */ 124 public NetworkBuilder<N, E> allowsParallelEdges(boolean allowsParallelEdges) { 125 this.allowsParallelEdges = allowsParallelEdges; 126 return this; 127 } 128 129 /** 130 * Specifies whether the network will allow self-loops (edges that connect a node to itself). 131 * Attempting to add a self-loop to a network that does not allow them will throw an {@link 132 * UnsupportedOperationException}. 133 * 134 * <p>The default value is {@code false}. 135 */ 136 public NetworkBuilder<N, E> allowsSelfLoops(boolean allowsSelfLoops) { 137 this.allowsSelfLoops = allowsSelfLoops; 138 return this; 139 } 140 141 /** 142 * Specifies the expected number of nodes in the network. 143 * 144 * @throws IllegalArgumentException if {@code expectedNodeCount} is negative 145 */ 146 public NetworkBuilder<N, E> expectedNodeCount(int expectedNodeCount) { 147 this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount)); 148 return this; 149 } 150 151 /** 152 * Specifies the expected number of edges in the network. 153 * 154 * @throws IllegalArgumentException if {@code expectedEdgeCount} is negative 155 */ 156 public NetworkBuilder<N, E> expectedEdgeCount(int expectedEdgeCount) { 157 this.expectedEdgeCount = Optional.of(checkNonNegative(expectedEdgeCount)); 158 return this; 159 } 160 161 /** 162 * Specifies the order of iteration for the elements of {@link Network#nodes()}. 163 * 164 * <p>The default value is {@link ElementOrder#insertion() insertion order}. 165 */ 166 public <N1 extends N> NetworkBuilder<N1, E> nodeOrder(ElementOrder<N1> nodeOrder) { 167 NetworkBuilder<N1, E> newBuilder = cast(); 168 newBuilder.nodeOrder = checkNotNull(nodeOrder); 169 return newBuilder; 170 } 171 172 /** 173 * Specifies the order of iteration for the elements of {@link Network#edges()}. 174 * 175 * <p>The default value is {@link ElementOrder#insertion() insertion order}. 176 */ 177 public <E1 extends E> NetworkBuilder<N, E1> edgeOrder(ElementOrder<E1> edgeOrder) { 178 NetworkBuilder<N, E1> newBuilder = cast(); 179 newBuilder.edgeOrder = checkNotNull(edgeOrder); 180 return newBuilder; 181 } 182 183 /** Returns an empty {@link MutableNetwork} with the properties of this {@link NetworkBuilder}. */ 184 public <N1 extends N, E1 extends E> MutableNetwork<N1, E1> build() { 185 return new ConfigurableMutableNetwork<>(this); 186 } 187 188 @SuppressWarnings("unchecked") 189 private <N1 extends N, E1 extends E> NetworkBuilder<N1, E1> cast() { 190 return (NetworkBuilder<N1, E1>) this; 191 } 192}