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.annotations.GwtIncompatible;
024import com.google.common.base.Optional;
025
026/**
027 * A builder for constructing instances of {@link MutableNetwork} with 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>Example of use:
039 *
040 * <pre>{@code
041 * MutableNetwork<String, Integer> flightNetwork =
042 *     NetworkBuilder.directed().allowsParallelEdges(true).build();
043 * flightNetwork.addEdge("LAX", "ATL", 3025);
044 * flightNetwork.addEdge("LAX", "ATL", 1598);
045 * flightNetwork.addEdge("ATL", "LAX", 2450);
046 * }</pre>
047 *
048 * @author James Sexton
049 * @author Joshua O'Madadhain
050 * @since 20.0
051 */
052@Beta
053@GwtIncompatible
054public final class NetworkBuilder<N, E> extends AbstractGraphBuilder<N> {
055  boolean allowsParallelEdges = false;
056  ElementOrder<? super E> edgeOrder = ElementOrder.insertion();
057  Optional<Integer> expectedEdgeCount = Optional.absent();
058
059  /** Creates a new instance with the specified edge directionality. */
060  private NetworkBuilder(boolean directed) {
061    super(directed);
062  }
063
064  /** Returns a {@link NetworkBuilder} for building directed networks. */
065  public static NetworkBuilder<Object, Object> directed() {
066    return new NetworkBuilder<Object, Object>(true);
067  }
068
069  /** Returns a {@link NetworkBuilder} for building undirected networks. */
070  public static NetworkBuilder<Object, Object> undirected() {
071    return new NetworkBuilder<Object, Object>(false);
072  }
073
074  /**
075   * Returns a {@link NetworkBuilder} initialized with all properties queryable from {@code
076   * network}.
077   *
078   * <p>The "queryable" properties are those that are exposed through the {@link Network} interface,
079   * such as {@link Network#isDirected()}. Other properties, such as {@link
080   * #expectedNodeCount(int)}, are not set in the new builder.
081   */
082  public static <N, E> NetworkBuilder<N, E> from(Network<N, E> network) {
083    return new NetworkBuilder<N, E>(network.isDirected())
084        .allowsParallelEdges(network.allowsParallelEdges())
085        .allowsSelfLoops(network.allowsSelfLoops())
086        .nodeOrder(network.nodeOrder())
087        .edgeOrder(network.edgeOrder());
088  }
089
090  /**
091   * Specifies whether the network will allow parallel edges. Attempting to add a parallel edge to a
092   * network that does not allow them will throw an {@link UnsupportedOperationException}.
093   */
094  public NetworkBuilder<N, E> allowsParallelEdges(boolean allowsParallelEdges) {
095    this.allowsParallelEdges = allowsParallelEdges;
096    return this;
097  }
098
099  /**
100   * Specifies whether the network will allow self-loops (edges that connect a node to itself).
101   * Attempting to add a self-loop to a network that does not allow them will throw an {@link
102   * UnsupportedOperationException}.
103   */
104  public NetworkBuilder<N, E> allowsSelfLoops(boolean allowsSelfLoops) {
105    this.allowsSelfLoops = allowsSelfLoops;
106    return this;
107  }
108
109  /**
110   * Specifies the expected number of nodes in the network.
111   *
112   * @throws IllegalArgumentException if {@code expectedNodeCount} is negative
113   */
114  public NetworkBuilder<N, E> expectedNodeCount(int expectedNodeCount) {
115    this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount));
116    return this;
117  }
118
119  /**
120   * Specifies the expected number of edges in the network.
121   *
122   * @throws IllegalArgumentException if {@code expectedEdgeCount} is negative
123   */
124  public NetworkBuilder<N, E> expectedEdgeCount(int expectedEdgeCount) {
125    this.expectedEdgeCount = Optional.of(checkNonNegative(expectedEdgeCount));
126    return this;
127  }
128
129  /** Specifies the order of iteration for the elements of {@link Network#nodes()}. */
130  public <N1 extends N> NetworkBuilder<N1, E> nodeOrder(ElementOrder<N1> nodeOrder) {
131    NetworkBuilder<N1, E> newBuilder = cast();
132    newBuilder.nodeOrder = checkNotNull(nodeOrder);
133    return newBuilder;
134  }
135
136  /** Specifies the order of iteration for the elements of {@link Network#edges()}. */
137  public <E1 extends E> NetworkBuilder<N, E1> edgeOrder(ElementOrder<E1> edgeOrder) {
138    NetworkBuilder<N, E1> newBuilder = cast();
139    newBuilder.edgeOrder = checkNotNull(edgeOrder);
140    return newBuilder;
141  }
142
143  /** Returns an empty {@link MutableNetwork} with the properties of this {@link NetworkBuilder}. */
144  public <N1 extends N, E1 extends E> MutableNetwork<N1, E1> build() {
145    return new ConfigurableMutableNetwork<N1, E1>(this);
146  }
147
148  @SuppressWarnings("unchecked")
149  private <N1 extends N, E1 extends E> NetworkBuilder<N1, E1> cast() {
150    return (NetworkBuilder<N1, E1>) this;
151  }
152}