include/geos/geom/CoordinateFilter.h

   1 /**********************************************************************
   2  *
   3  * GEOS - Geometry Engine Open Source
   4  * http://geos.osgeo.org
   5  *
   6  * Copyright (C) 2005-2006 Refractions Research Inc.
   7  *
   8  * This is free software; you can redistribute and/or modify it under
   9  * the terms of the GNU Lesser General Public Licence as published
  10  * by the Free Software Foundation.
  11  * See the COPYING file for more information.
  12  *
  13  **********************************************************************/
  14
  15 #ifndef GEOS_GEOM_COORDINATEFILTER_H
  16 #define GEOS_GEOM_COORDINATEFILTER_H
  17
  18 #include <geos/export.h>
  19 #include <geos/inline.h>
  20
  21 #include <cassert>
  22
  23 namespace geos {
  24 namespace geom { // geos::geom
  25
  26 class Coordinate;
  27
  28 /**
  29  * <code>Geometry</code> classes support the concept of applying a
  30  * coordinate filter to every coordinate in the <code>Geometry</code>.
  31  *
  32  * A  coordinate filter can either record information about each coordinate or
  33  * change the coordinate in some way. Coordinate filters implement the
  34  * interface <code>CoordinateFilter</code>. (<code>CoordinateFilter</code> is
  35  * an example of the Gang-of-Four Visitor pattern). Coordinate filters can be
  36  * used to implement such things as coordinate transformations, centroid and
  37  * envelope computation, and many other functions.
  38  *
  39  * TODO: provide geom::CoordinateInspector and geom::CoordinateMutator instead
  40  * of having the two versions of filter_rw and filter_ro
  41  *
  42  */
  43 class GEOS_DLL CoordinateFilter {
  44 public:
  45    virtual ~CoordinateFilter() {}
  46
  47    /**
  48     * Performs an operation on <code>coord</code>.
  49     *
  50     * @param  coord  a <code>Coordinate</code> to which the filter is applied.
  51     */
  52    virtual void filter_rw(Coordinate* /*coord*/) const { assert(0); }
  53
  54    /**
  55     * Performs an operation with <code>coord</code>.
  56     *
  57     * @param  coord  a <code>Coordinate</code> to which the filter is applied.
  58     */
  59    virtual void filter_ro(const Coordinate* /*coord*/) { assert(0); }
  60 };
  61
  62 } // namespace geos::geom
  63 } // namespace geos
  64
  65 //#ifdef GEOS_INLINE
  66 //# include "geos/geom/CoordinateFilter.inl"
  67 //#endif
  68
  69 #endif // ndef GEOS_GEOM_COORDINATEFILTER_H
  70
  71 /**********************************************************************
  72  * $Log$
  73  * Revision 1.4  2006/06/19 23:33:03  strk
  74  * Don't *require* CoordinateFilters to define both read-only and read-write methods.
  75  *
  76  * Revision 1.3  2006/03/24 09:52:41  strk
  77  * USE_INLINE => GEOS_INLINE
  78  *
  79  * Revision 1.2  2006/03/13 21:13:54  strk
  80  * Added comment about possible refactoring
  81  *
  82  * Revision 1.1  2006/03/09 16:46:49  strk
  83  * geos::geom namespace definition, first pass at headers split
  84  *
  85  **********************************************************************/