/*
 * 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.geom;

/**
 * Interface for classeswhich provide operations that can be applied to the
 * coordinates in a {@link CoordinateSequence}. A CoordinateSequence filter can
 * either record information about each coordinate or change the coordinate in
 * some way. CoordinateSequence filters can be used to implement such things as
 * coordinate transformations, centroid and envelope computation, and many other
 * functions. For maximum efficiency, the execution of filters can be
 * short-circuited. {@link Geometry} classes support the concept of applying a
 * <code>CoordinateSequenceFilter</code> to each {@link CoordinateSequence}s
 * they contain.
 * <p>
 * <code>CoordinateSequenceFilter</code> is an example of the Gang-of-Four
 * Visitor pattern.
 * 
 *@see Geometry#apply(CoordinateSequenceFilter)
 *@author Martin Davis
 *@version 1.7
 */
public interface CoordinateSequenceFilter {
	/**
	 * Performs an operation on a coordinate in a {@link CoordinateSequence}.
	 * 
	 *@param seq
	 *            the <code>CoordinateSequence</code> to which the filter is
	 *            applied
	 *@param i
	 *            the index of the coordinate to apply the filter to
	 */
	void filter(CoordinateSequence seq, int i);

	/**
	 * Reports whether the application of this filter can be terminated. Once
	 * this method returns <tt>false</tt>, it should continue to return
	 * <tt>false</tt> on every subsequent call.
	 * 
	 * @return true if the application of this filter can be terminated.
	 */
	boolean isDone();

	/**
	 * Reports whether the execution of this filter has modified the coordinates
	 * of the geometry. If so, {@link Geometry#geometryChanged} will be
	 * executed.
	 * <p>
	 * Most filters can simply return a constant value reflecting whether they
	 * are able to change the coordinates.
	 * 
	 * @return true if this filter has changed the coordinates of the geometry
	 */
	boolean isGeometryChanged();
}