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 * @since 20.0
050 */
051@Beta
052public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> {
053  boolean allowsParallelEdges = false;
054  ElementOrder<? super E> edgeOrder = ElementOrder.insertion();
055  Optional<Integer> expectedEdgeCount = Optional.absent();
056
057  /** Creates a new instance with the specified edge directionality. */
058  private NetworkBuilder(boolean directed) {
059    super(directed);
060  }
061
062  /** Returns a {@link NetworkBuilder} for building directed networks. */
063  public static NetworkBuilder<Object, Object> directed() {
064    return new NetworkBuilder<>(true);
065  }
066
067  /** Returns a {@link NetworkBuilder} for building undirected networks. */
068  public static NetworkBuilder<Object, Object> undirected() {
069    return new NetworkBuilder<>(false);
070  }
071
072  /**
073   * Returns a {@link NetworkBuilder} initialized with all properties queryable from {@code
074   * network}.
075   *
076   * <p>The "queryable" properties are those that are exposed through the {@link Network} interface,
077   * such as {@link Network#isDirected()}. Other properties, such as {@link
078   * #expectedNodeCount(int)}, are not set in the new builder.
079   */
080  public static <N, E> NetworkBuilder<N, E> from(Network<N, E> network) {
081    return new NetworkBuilder<N, E>(network.isDirected())
082        .allowsParallelEdges(network.allowsParallelEdges())
083        .allowsSelfLoops(network.allowsSelfLoops())
084        .nodeOrder(network.nodeOrder())
085        .edgeOrder(network.edgeOrder());
086  }
087
088  /**
089   * Specifies whether the network will allow parallel edges. Attempting to add a parallel edge to a
090   * network that does not allow them will throw an {@link UnsupportedOperationException}.
091   */
092  public NetworkBuilder<N, E> allowsParallelEdges(boolean allowsParallelEdges) {
093    this.allowsParallelEdges = allowsParallelEdges;
094    return this;
095  }
096
097  /**
098   * Specifies whether the network will allow self-loops (edges that connect a node to itself).
099   * Attempting to add a self-loop to a network that does not allow them will throw an {@link
100   * UnsupportedOperationException}.
101   */
102  public NetworkBuilder<N, E> allowsSelfLoops(boolean allowsSelfLoops) {
103    this.allowsSelfLoops = allowsSelfLoops;
104    return this;
105  }
106
107  /**
108   * Specifies the expected number of nodes in the network.
109   *
110   * @throws IllegalArgumentException if {@code expectedNodeCount} is negative
111   */
112  public NetworkBuilder<N, E> expectedNodeCount(int expectedNodeCount) {
113    this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount));
114    return this;
115  }
116
117  /**
118   * Specifies the expected number of edges in the network.
119   *
120   * @throws IllegalArgumentException if {@code expectedEdgeCount} is negative
121   */
122  public NetworkBuilder<N, E> expectedEdgeCount(int expectedEdgeCount) {
123    this.expectedEdgeCount = Optional.of(checkNonNegative(expectedEdgeCount));
124    return this;
125  }
126
127  /** Specifies the order of iteration for the elements of {@link Network#nodes()}. */
128  public <N1 extends N> NetworkBuilder<N1, E> nodeOrder(ElementOrder<N1> nodeOrder) {
129    NetworkBuilder<N1, E> newBuilder = cast();
130    newBuilder.nodeOrder = checkNotNull(nodeOrder);
131    return newBuilder;
132  }
133
134  /** Specifies the order of iteration for the elements of {@link Network#edges()}. */
135  public <E1 extends E> NetworkBuilder<N, E1> edgeOrder(ElementOrder<E1> edgeOrder) {
136    NetworkBuilder<N, E1> newBuilder = cast();
137    newBuilder.edgeOrder = checkNotNull(edgeOrder);
138    return newBuilder;
139  }
140
141  /** Returns an empty {@link MutableNetwork} with the properties of this {@link NetworkBuilder}. */
142  public <N1 extends N, E1 extends E> MutableNetwork<N1, E1> build() {
143    return new ConfigurableMutableNetwork<>(this);
144  }
145
146  @SuppressWarnings("unchecked")
147  private <N1 extends N, E1 extends E> NetworkBuilder<N1, E1> cast() {
148    return (NetworkBuilder<N1, E1>) this;
149  }
150}