Java example source code file (NetworkBuilder.java)

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Java - Java tags/keywords

beta, configurablemutablenetwork, elementorder, mutablenetwork, networkbuilder, object, optional, suppresswarnings, the

The NetworkBuilder.java Java example source code

/*
 * Copyright (C) 2016 The Guava Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.common.graph;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.Beta;
import com.google.common.base.Optional;

/**
 * A builder for constructing instances of {@link Network} with user-defined properties.
 *
 * <p>A graph built by this class will have the following properties by default:
 * <ul>
 * <li>does not allow parallel edges
 * <li>allows self-loops
 * <li>orders {@code nodes()} and {@code edges()} in the order in which the elements were added
 * </ul>
 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @since 20.0
 */
@Beta
public final class NetworkBuilder<N, E> {
  final boolean directed;
  boolean allowsParallelEdges = false;
  boolean allowsSelfLoops = true;
  ElementOrder<? super N> nodeOrder = ElementOrder.insertion();
  ElementOrder<? super E> edgeOrder = ElementOrder.insertion();
  Optional<Integer> expectedNodeCount = Optional.absent();
  Optional<Integer> expectedEdgeCount = Optional.absent();

  /**
   * Creates a new instance with the specified edge directionality.
   *
   * @param directed if true, creates an instance for graphs whose edges are each directed;
   *      if false, creates an instance for graphs whose edges are each undirected.
   */
  private NetworkBuilder(boolean directed) {
    this.directed = directed;
  }

  /**
   * Returns a {@link NetworkBuilder} for building directed graphs.
   */
  public static NetworkBuilder<Object, Object> directed() {
    return new NetworkBuilder<Object, Object>(true);
  }

  /**
   * Returns a {@link NetworkBuilder} for building undirected graphs.
   */
  public static NetworkBuilder<Object, Object> undirected() {
    return new NetworkBuilder<Object, Object>(false);
  }

  /**
   * Returns a {@link NetworkBuilder} initialized with all properties queryable from {@code graph}.
   *
   * <p>The "queryable" properties are those that are exposed through the {@link Network} interface,
   * such as {@link Network#isDirected()}. Other properties, such as
   * {@link #expectedNodeCount(int)}, are not set in the new builder.
   */
  public static <N, E> NetworkBuilder from(Network graph) {
    checkNotNull(graph);
    return new NetworkBuilder<Object, Object>(graph.isDirected())
        .allowsParallelEdges(graph.allowsParallelEdges())
        .allowsSelfLoops(graph.allowsSelfLoops())
        .nodeOrder(graph.nodeOrder())
        .edgeOrder(graph.edgeOrder())
        .cast();
  }

  /**
   * Specifies whether the graph will allow parallel edges. Attempting to add a parallel edge to
   * a graph that does not allow them will throw an {@link UnsupportedOperationException}.
   */
  public NetworkBuilder<N, E> allowsParallelEdges(boolean allowsParallelEdges) {
    this.allowsParallelEdges = allowsParallelEdges;
    return this;
  }

  /**
   * Specifies whether the graph will allow self-loops (edges that connect a node to itself).
   * Attempting to add a self-loop to a graph that does not allow them will throw an
   * {@link UnsupportedOperationException}.
   */
  public NetworkBuilder<N, E> allowsSelfLoops(boolean allowsSelfLoops) {
    this.allowsSelfLoops = allowsSelfLoops;
    return this;
  }

  /**
   * Specifies the expected number of nodes in the graph.
   *
   * @throws IllegalArgumentException if {@code expectedNodeCount} is negative
   */
  public NetworkBuilder<N, E> expectedNodeCount(int expectedNodeCount) {
    checkArgument(expectedNodeCount >= 0, "The expected number of nodes can't be negative: %s",
        expectedNodeCount);
    this.expectedNodeCount = Optional.of(expectedNodeCount);
    return this;
  }

  /**
   * Specifies the expected number of edges in the graph.
   *
   * @throws IllegalArgumentException if {@code expectedEdgeCount} is negative
   */
  public NetworkBuilder<N, E> expectedEdgeCount(int expectedEdgeCount) {
    checkArgument(expectedEdgeCount >= 0, "The expected number of edges can't be negative: %s",
        expectedEdgeCount);
    this.expectedEdgeCount = Optional.of(expectedEdgeCount);
    return this;
  }

  /**
   * Specifies the order of iteration for the elements of {@link Network#nodes()}.
   */
  public <N1 extends N> NetworkBuilder nodeOrder(ElementOrder nodeOrder) {
    checkNotNull(nodeOrder);
    NetworkBuilder<N1, E> newBuilder = cast();
    newBuilder.nodeOrder = nodeOrder;
    return newBuilder;
  }

  /**
   * Specifies the order of iteration for the elements of {@link Network#edges()}.
   */
  public <E1 extends E> NetworkBuilder edgeOrder(ElementOrder edgeOrder) {
    checkNotNull(edgeOrder);
    NetworkBuilder<N, E1> newBuilder = cast();
    newBuilder.edgeOrder = edgeOrder;
    return newBuilder;
  }

  /**
   * Returns an empty {@link MutableNetwork} with the properties of this {@link NetworkBuilder}.
   */
  public <N1 extends N, E1 extends E> MutableNetwork build() {
    return new ConfigurableMutableNetwork<N1, E1>(this);
  }

  @SuppressWarnings("unchecked")
  private <N1 extends N, E1 extends E> NetworkBuilder cast() {
    return (NetworkBuilder<N1, E1>) this;
  }
}