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 MutableValueGraph} with user-defined properties. 027 * 028 * <p>A graph built by this class will have the following properties by default: 029 * 030 * <ul> 031 * <li>does not allow self-loops 032 * <li>orders {@link Graph#nodes()} in the order in which the elements were added 033 * </ul> 034 * 035 * <p>Example of use: 036 * 037 * <pre>{@code 038 * MutableValueGraph<String, Double> graph = 039 * ValueGraphBuilder.undirected().allowsSelfLoops(true).build(); 040 * graph.putEdgeValue("San Francisco", "San Francisco", 0.0); 041 * graph.putEdgeValue("San Jose", "San Jose", 0.0); 042 * graph.putEdgeValue("San Francisco", "San Jose", 48.4); 043 * }</pre> 044 * 045 * @author James Sexton 046 * @author Joshua O'Madadhain 047 * @param <N> The most general node type this builder will support. This is normally {@code Object} 048 * unless it is constrained by using a method like {@link #nodeOrder}, or the builder is 049 * constructed based on an existing {@code ValueGraph} using {@link #from(ValueGraph)}. 050 * @param <V> The most general value type this builder will support. This is normally {@code Object} 051 * unless the builder is constructed based on an existing {@code Graph} using {@link 052 * #from(ValueGraph)}. 053 * @since 20.0 054 */ 055@Beta 056public final class ValueGraphBuilder<N, V> extends AbstractGraphBuilder<N> { 057 058 /** Creates a new instance with the specified edge directionality. */ 059 private ValueGraphBuilder(boolean directed) { 060 super(directed); 061 } 062 063 /** Returns a {@link ValueGraphBuilder} for building directed graphs. */ 064 public static ValueGraphBuilder<Object, Object> directed() { 065 return new ValueGraphBuilder<>(true); 066 } 067 068 /** Returns a {@link ValueGraphBuilder} for building undirected graphs. */ 069 public static ValueGraphBuilder<Object, Object> undirected() { 070 return new ValueGraphBuilder<>(false); 071 } 072 073 /** 074 * Returns a {@link ValueGraphBuilder} initialized with all properties queryable from {@code 075 * graph}. 076 * 077 * <p>The "queryable" properties are those that are exposed through the {@link ValueGraph} 078 * interface, such as {@link ValueGraph#isDirected()}. Other properties, such as {@link 079 * #expectedNodeCount(int)}, are not set in the new builder. 080 */ 081 public static <N, V> ValueGraphBuilder<N, V> from(ValueGraph<N, V> graph) { 082 return new ValueGraphBuilder<N, V>(graph.isDirected()) 083 .allowsSelfLoops(graph.allowsSelfLoops()) 084 .nodeOrder(graph.nodeOrder()); 085 } 086 087 /** 088 * Specifies whether the graph will allow self-loops (edges that connect a node to itself). 089 * Attempting to add a self-loop to a graph that does not allow them will throw an {@link 090 * UnsupportedOperationException}. 091 */ 092 public ValueGraphBuilder<N, V> allowsSelfLoops(boolean allowsSelfLoops) { 093 this.allowsSelfLoops = allowsSelfLoops; 094 return this; 095 } 096 097 /** 098 * Specifies the expected number of nodes in the graph. 099 * 100 * @throws IllegalArgumentException if {@code expectedNodeCount} is negative 101 */ 102 public ValueGraphBuilder<N, V> expectedNodeCount(int expectedNodeCount) { 103 this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount)); 104 return this; 105 } 106 107 /** Specifies the order of iteration for the elements of {@link Graph#nodes()}. */ 108 public <N1 extends N> ValueGraphBuilder<N1, V> nodeOrder(ElementOrder<N1> nodeOrder) { 109 ValueGraphBuilder<N1, V> newBuilder = cast(); 110 newBuilder.nodeOrder = checkNotNull(nodeOrder); 111 return newBuilder; 112 } 113 114 /** 115 * Returns an empty {@link MutableValueGraph} with the properties of this {@link 116 * ValueGraphBuilder}. 117 */ 118 public <N1 extends N, V1 extends V> MutableValueGraph<N1, V1> build() { 119 return new ConfigurableMutableValueGraph<>(this); 120 } 121 122 @SuppressWarnings("unchecked") 123 private <N1 extends N, V1 extends V> ValueGraphBuilder<N1, V1> cast() { 124 return (ValueGraphBuilder<N1, V1>) this; 125 } 126}