ext/OGDF/ogdf/basic/GraphObserver.h

   1 /*
   2  * $Revision: 2615 $
   3  *
   4  * last checkin:
   5  *   $Author: gutwenger $
   6  *   $Date: 2012-07-16 14:23:36 +0200 (Mo, 16. Jul 2012) $
   7  ***************************************************************/
   8
   9 /** \file
  10  * \brief Abstract base class for structures on graphs, that need
  11  *        to be informed about graph changes (e.g. cluster graphs).
  12  *
  13  * Follows the observer pattern: graphs are observable
  14  * objects that can inform observers on changes made to their
  15  * structure.
  16  *
  17  * \author Karsten Klein
  18  *
  19  * \par License:
  20  * This file is part of the Open Graph Drawing Framework (OGDF).
  21  *
  22  * \par
  23  * Copyright (C)<br>
  24  * See README.txt in the root directory of the OGDF installation for details.
  25  *
  26  * \par
  27  * This program is free software; you can redistribute it and/or
  28  * modify it under the terms of the GNU General Public License
  29  * Version 2 or 3 as published by the Free Software Foundation;
  30  * see the file LICENSE.txt included in the packaging of this file
  31  * for details.
  32  *
  33  * \par
  34  * This program is distributed in the hope that it will be useful,
  35  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  36  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  37  * GNU General Public License for more details.
  38  *
  39  * \par
  40  * You should have received a copy of the GNU General Public
  41  * License along with this program; if not, write to the Free
  42  * Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  43  * Boston, MA 02110-1301, USA.
  44  *
  45  * \see  http://www.gnu.org/copyleft/gpl.html
  46  ***************************************************************/
  47
  48
  49 #ifdef _MSC_VER
  50 #pragma once
  51 #endif
  52
  53 #ifndef OGDF_GRAPH_STRUCTURE_H
  54 #define OGDF_GRAPH_STRUCTURE_H
  55
  56
  57 #include <ogdf/basic/List.h>
  58 #include <ogdf/basic/Graph.h>
  59
  60 namespace ogdf {
  61
  62 //
  63 // in embedded graphs, adjacency lists are given in clockwise order.
  64 //
  65
  66
  67 //----------------------------------------------------------
  68 // GraphObserver
  69 //----------------------------------------------------------
  70 /**
  71  * \brief Abstract Base class for classes that need to keep track
  72  * of changes in the graph like addition/deletion of nodes
  73  * or edges.
  74  * derived classes have to overload nodeDeleted, nodeAdded
  75  * edgeDeleted, edgeAdded
  76  * these functions should be called by Graph before (delete)
  77  *
  78  */
  79
  80 class OGDF_EXPORT GraphObserver {
  81         friend class Graph;
  82
  83 public:
  84         //! Constructs instance of GraphObserver class
  85         GraphObserver() : m_pGraph(0) { }
  86
  87         /**
  88          *\brief Constructs instance of GraphObserver class
  89          * \param G is the graph to be watched
  90          */
  91         GraphObserver(const Graph* G) : m_pGraph(G)
  92         {
  93                 m_itGList = G->registerStructure(this);
  94         }//constructor
  95
  96         //! Destroys the instance, unregisters it from watched graph
  97         virtual ~GraphObserver()
  98         {
  99                 if (m_pGraph) m_pGraph->unregisterStructure(m_itGList);
 100         }//destructor
 101
 102         //! Associates observer instance with graph \a G
 103         void reregister(const Graph *pG) {
 104                 //small speedup: check if == m_pGraph
 105                 if (m_pGraph) m_pGraph->unregisterStructure(m_itGList);
 106                 if ((m_pGraph = pG) != 0) m_itGList = pG->registerStructure(this);
 107         }
 108
 109         //! Called by watched graph when a node is deleted
 110         //! Has to be implemented by derived classes
 111         virtual void nodeDeleted(node v) = 0;
 112
 113         //! Called by watched graph when a node is added
 114         //! Has to be implemented by derived classes
 115         virtual void nodeAdded(node v)   = 0;
 116
 117         //! Called by watched graph when an edge is deleted
 118         //! Has to be implemented by derived classes
 119         virtual void edgeDeleted(edge e) = 0;
 120
 121         //! Called by watched graph when an edge is added
 122         //! Has to be implemented by derived classes
 123         virtual void edgeAdded(edge e)   = 0;
 124
 125         //! Called by watched graph when it is reinitialized
 126         //! Has to be implemented by derived classes
 127         virtual void reInit()            = 0;
 128
 129         //! Called by watched graph when its clear function is called
 130         //! Has to be implemented by derived classes
 131         virtual void cleared()           = 0;
 132
 133         const Graph*  getGraph() const { return m_pGraph; }
 134
 135 protected:
 136         const Graph* m_pGraph; //! watched graph
 137         ListIterator<GraphObserver*> m_itGList; //! List entry in graphs list of all registered graphobservers
 138
 139
 140 };
 141
 142 } //end namespace ogdf
 143
 144 #endif