SIRtree.java

/*
 * The JTS Topology Suite is a collection of Java classes that
 * implement the fundamental operations required to validate a given
 * geo-spatial data set to a known topological specification.
 *
 * Copyright (C) 2001 Vivid Solutions
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 * For more information, contact:
 *
 *     Vivid Solutions
 *     Suite #1A
 *     2328 Government Street
 *     Victoria BC  V8T 5G5
 *     Canada
 *
 *     (250)385-6040
 *     www.vividsolutions.com
 */
package com.vividsolutions.jts.index.strtree;

import java.util.Comparator;
import java.util.Iterator;
import java.util.List;

/**
 * One-dimensional version of an STR-packed R-tree. SIR stands for
 * "Sort-Interval-Recursive". STR-packed R-trees are described in:
 * P. Rigaux, Michel Scholl and Agnes Voisard. Spatial Databases With
 * Application To GIS. Morgan Kaufmann, San Francisco, 2002.
 * @see STRtree
 *
 * @version 1.7
 */
public class SIRtree extends AbstractSTRtree {

  private Comparator comparator = new Comparator() {
    public int compare(Object o1, Object o2) {
      return compareDoubles(
          ((Interval)((Boundable)o1).getBounds()).getCentre(),
          ((Interval)((Boundable)o2).getBounds()).getCentre());
    }
  };

  private IntersectsOp intersectsOp = new IntersectsOp() {
    public boolean intersects(Object aBounds, Object bBounds) {
      return ((Interval)aBounds).intersects((Interval)bBounds);
    }
  };
  
  /**
   * Constructs an SIRtree with the default node capacity.
   */
  public SIRtree() { this(10); }
   
  /**
   * Constructs an SIRtree with the given maximum number of child nodes that
   * a node may have
   */
  public SIRtree(int nodeCapacity) {
    super(nodeCapacity);
  }

  protected AbstractNode createNode(int level) {
    return new AbstractNode(level) {
      protected Object computeBounds() {
        Interval bounds = null;
        for (Iterator i = getChildBoundables().iterator(); i.hasNext(); ) {
          Boundable childBoundable = (Boundable) i.next();
          if (bounds == null) {
            bounds = new Interval((Interval)childBoundable.getBounds());
          }
          else {
            bounds.expandToInclude((Interval)childBoundable.getBounds());
          }
        }
        return bounds;
      }
    };
  }

  /**
   * Inserts an item having the given bounds into the tree.
   */
  public void insert(double x1, double x2, Object item) {
    super.insert(new Interval(Math.min(x1, x2), Math.max(x1, x2)), item);
  }

  /**
   * Returns items whose bounds intersect the given value.
   */
  public List query(double x) {
    return query(x, x);
  }

  /**
   * Returns items whose bounds intersect the given bounds.
   * @param x1 possibly equal to x2
   */
  public List query(double x1, double x2) {
    return super.query(new Interval(Math.min(x1, x2), Math.max(x1, x2)));
  }

  protected IntersectsOp getIntersectsOp() {
    return intersectsOp;
  }

  protected Comparator getComparator() {
    return comparator;
  }

}