
/*
 * Copyright (c) 2016 Vivid Solutions.
 *
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License 2.0
 * and Eclipse Distribution License v. 1.0 which accompanies this distribution.
 * The Eclipse Public License is available at http://www.eclipse.org/legal/epl-v20.html
 * and the Eclipse Distribution License is available at
 *
 * http://www.eclipse.org/org/documents/edl-v10.php.
 */
package org.locationtech.jts.planargraph;

import java.util.Iterator;

/**
 * The base class for all graph component classes.
 * Maintains flags of use in generic graph algorithms.
 * Provides two flags:
 * <ul>
 * <li><b>marked</b> - typically this is used to indicate a state that persists
 * for the course of the graph's lifetime.  For instance, it can be
 * used to indicate that a component has been logically deleted from the graph.
 * <li><b>visited</b> - this is used to indicate that a component has been processed
 * or visited by an single graph algorithm.  For instance, a breadth-first traversal of the
 * graph might use this to indicate that a node has already been traversed.
 * The visited flag may be set and cleared many times during the lifetime of a graph.
 * </ul>
 *
 * <p>
 * Graph components support storing user context data.  This will typically be
 * used by client algorithms which use planar graphs.
 *
 * @version 1.7
 */
public abstract class GraphComponent
{
  /**
   * Sets the Visited state for all {@link GraphComponent}s in an {@link Iterator}
   *
   * @param i the Iterator to scan
   * @param visited the state to set the visited flag to
   */
  public static void setVisited(Iterator i, boolean visited)
  {
    while (i.hasNext()) {
      GraphComponent comp = (GraphComponent) i.next();
      comp.setVisited(visited);
    }
  }

  /**
   * Sets the Marked state for all {@link GraphComponent}s in an {@link Iterator}
   *
   * @param i the Iterator to scan
   * @param marked the state to set the Marked flag to
   */
  public static void setMarked(Iterator i, boolean marked)
  {
    while (i.hasNext()) {
      GraphComponent comp = (GraphComponent) i.next();
      comp.setMarked(marked);
    }
  }

  /**
   * Finds the first {@link GraphComponent} in a {@link Iterator} set
   * which has the specified visited state.
   *
   * @param i an Iterator of GraphComponents
   * @param visitedState the visited state to test
   * @return the first component found, or <code>null</code> if none found
   */
  public static GraphComponent getComponentWithVisitedState(Iterator i, boolean visitedState)
  {
    while (i.hasNext()) {
      GraphComponent comp = (GraphComponent) i.next();
      if (comp.isVisited() == visitedState)
        return comp;
    }
    return null;
  }

  protected boolean isMarked = false;
  protected boolean isVisited = false;
  private Object data;

  public GraphComponent() {
  }

  /**
   * Tests if a component has been visited during the course of a graph algorithm
   * @return <code>true</code> if the component has been visited
   */
  public boolean isVisited() { return isVisited; }

  /**
   * Sets the visited flag for this component.
   * @param isVisited the desired value of the visited flag
   */
  public void setVisited(boolean isVisited) { this.isVisited = isVisited; }

  /**
   * Tests if a component has been marked at some point during the processing
   * involving this graph.
   * @return <code>true</code> if the component has been marked
   */
  public boolean isMarked() { return isMarked; }

  /**
   * Sets the marked flag for this component.
   * @param isMarked the desired value of the marked flag
   */
  public void setMarked(boolean isMarked) { this.isMarked = isMarked; }

  /**
   * Sets the user-defined data for this component.
   *
   * @param data an Object containing user-defined data
   */
  public void setContext(Object data) { this.data = data; }

  /**
   * Gets the user-defined data for this component.
   *
   * @return the user-defined data
   */
  public Object getContext() { return data; }

  /**
   * Sets the user-defined data for this component.
   *
   * @param data an Object containing user-defined data
   */
  public void setData(Object data) { this.data = data; }

  /**
   * Gets the user-defined data for this component.
   *
   * @return the user-defined data
   */
  public Object getData() { return data; }

  /**
   * Tests whether this component has been removed from its containing graph
   *
   * @return <code>true</code> if this component is removed
   */
  public abstract boolean isRemoved();
}
