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/*
 * 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 static com.google.common.graph.Graphs.checkNonNegative;

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

/**
 * A builder for constructing instances of {@link MutableGraph} or {@link ImmutableGraph} with
 * user-defined properties.
 *
 * 
A graph built by this class will have the following properties by default:
 *
 * 
    
 *   
  • does not allow self-loops
 *   
  • orders {@link Graph#nodes()} in the order in which the elements were added
 * 

 *
 * 
Examples of use:
 *
 * 
{@code
 * // Building a mutable graph
 * MutableGraph graph = GraphBuilder.undirected().allowsSelfLoops(true).build();
 * graph.putEdge("bread", "bread");
 * graph.putEdge("chocolate", "peanut butter");
 * graph.putEdge("peanut butter", "jelly");
 *
 * // Building an immutable graph
 * ImmutableGraph immutableGraph =
 *     GraphBuilder.undirected()
 *         .allowsSelfLoops(true)
 *         .immutable()
 *         .putEdge("bread", "bread")
 *         .putEdge("chocolate", "peanut butter")
 *         .putEdge("peanut butter", "jelly")
 *         .build();
 * }

 *
 * @author James Sexton
 * @author Joshua O'Madadhain
 * @param  The most general node type this builder will support. This is normally {@code Object}
 *     unless it is constrained by using a method like {@link #nodeOrder}, or the builder is
 *     constructed based on an existing {@code Graph} using {@link #from(Graph)}.
 * @since 20.0
 */
@Beta
public final class GraphBuilder extends AbstractGraphBuilder {

  /** Creates a new instance with the specified edge directionality. */
  private GraphBuilder(boolean directed) {
    super(directed);
  }

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

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

  /**
   * Returns a {@link GraphBuilder} initialized with all properties queryable from {@code graph}.
   *
   * 
The "queryable" properties are those that are exposed through the {@link Graph} interface,
   * such as {@link Graph#isDirected()}. Other properties, such as {@link #expectedNodeCount(int)},
   * are not set in the new builder.
   */
  public static  GraphBuilder from(Graph graph) {
    return new GraphBuilder(graph.isDirected())
        .allowsSelfLoops(graph.allowsSelfLoops())
        .nodeOrder(graph.nodeOrder());
    // TODO(b/142723300): Add incidentEdgeOrder
  }

  /**
   * Returns an {@link ImmutableGraph.Builder} with the properties of this {@link GraphBuilder}.
   *
   * 
The returned builder can be used for populating an {@link ImmutableGraph}.
   *
   * 
Note that the returned builder will always have {@link #incidentEdgeOrder} set to {@link
   * ElementOrder#stable()}, regardless of the value that was set in this builder.
   *
   * @since 28.0
   */
  public  ImmutableGraph.Builder immutable() {
    GraphBuilder castBuilder = cast();
    return new ImmutableGraph.Builder<>(castBuilder);
  }

  /**
   * 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}.
   *
   * 
The default value is {@code false}.
   */
  public GraphBuilder 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 GraphBuilder expectedNodeCount(int expectedNodeCount) {
    this.expectedNodeCount = Optional.of(checkNonNegative(expectedNodeCount));
    return this;
  }

  /**
   * Specifies the order of iteration for the elements of {@link Graph#nodes()}.
   *
   * 
The default value is {@link ElementOrder#insertion() insertion order}.
   */
  public  GraphBuilder nodeOrder(ElementOrder nodeOrder) {
    GraphBuilder newBuilder = cast();
    newBuilder.nodeOrder = checkNotNull(nodeOrder);
    return newBuilder;
  }

  /**
   * Specifies the order of iteration for the elements of {@link Graph#edges()}, {@link
   * Graph#adjacentNodes(Object)}, {@link Graph#predecessors(Object)}, {@link
   * Graph#successors(Object)} and {@link Graph#incidentEdges(Object)}.
   *
   * 
The default value is {@link ElementOrder#unordered() unordered} for mutable graphs. For
   * immutable graphs, this value is ignored; they always have a {@link ElementOrder#stable()
   * stable} order.
   *
   * @throws IllegalArgumentException if {@code incidentEdgeOrder} is not either {@code
   *     ElementOrder.unordered()} or {@code ElementOrder.stable()}.
   */
  // TODO(b/142723300): Make this method public
   GraphBuilder incidentEdgeOrder(ElementOrder incidentEdgeOrder) {
    checkArgument(
        incidentEdgeOrder.type() == ElementOrder.Type.UNORDERED
            || incidentEdgeOrder.type() == ElementOrder.Type.STABLE,
        "The given elementOrder (%s) is unsupported. incidentEdgeOrder() only supports"
            + " ElementOrder.unordered() and ElementOrder.stable().",
        incidentEdgeOrder);
    GraphBuilder newBuilder = cast();
    newBuilder.incidentEdgeOrder = checkNotNull(incidentEdgeOrder);
    return newBuilder;
  }

  /** Returns an empty {@link MutableGraph} with the properties of this {@link GraphBuilder}. */
  public  MutableGraph build() {
    return new ConfigurableMutableGraph(this);
  }

  GraphBuilder copy() {
    GraphBuilder newBuilder = new GraphBuilder<>(directed);
    newBuilder.allowsSelfLoops = allowsSelfLoops;
    newBuilder.nodeOrder = nodeOrder;
    newBuilder.expectedNodeCount = expectedNodeCount;
    newBuilder.incidentEdgeOrder = incidentEdgeOrder;
    return newBuilder;
  }

  @SuppressWarnings("unchecked")
  private  GraphBuilder cast() {
    return (GraphBuilder) this;
  }
}
    

    

    

            

    

            



    
    






    
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