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