ext/OGDF/ogdf/decomposition/PertinentGraph.h

   1 /*
   2  * $Revision: 2523 $
   3  *
   4  * last checkin:
   5  *   $Author: gutwenger $
   6  *   $Date: 2012-07-02 20:59:27 +0200 (Mon, 02 Jul 2012) $
   7  ***************************************************************/
   8
   9 /** \file
  10  * \brief Declaration of class PertinentGraph.
  11  *
  12  * \author Carsten Gutwenger
  13  *
  14  * \par License:
  15  * This file is part of the Open Graph Drawing Framework (OGDF).
  16  *
  17  * \par
  18  * Copyright (C)<br>
  19  * See README.txt in the root directory of the OGDF installation for details.
  20  *
  21  * \par
  22  * This program is free software; you can redistribute it and/or
  23  * modify it under the terms of the GNU General Public License
  24  * Version 2 or 3 as published by the Free Software Foundation;
  25  * see the file LICENSE.txt included in the packaging of this file
  26  * for details.
  27  *
  28  * \par
  29  * This program is distributed in the hope that it will be useful,
  30  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  31  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  32  * GNU General Public License for more details.
  33  *
  34  * \par
  35  * You should have received a copy of the GNU General Public
  36  * License along with this program; if not, write to the Free
  37  * Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
  38  * Boston, MA 02110-1301, USA.
  39  *
  40  * \see  http://www.gnu.org/copyleft/gpl.html
  41  ***************************************************************/
  42
  43
  44 #ifdef _MSC_VER
  45 #pragma once
  46 #endif
  47
  48
  49 #ifndef OGDF_PERTINENT_GRAPH_H
  50 #define OGDF_PERTINENT_GRAPH_H
  51
  52
  53 namespace ogdf {
  54
  55         class OGDF_EXPORT SPQRTree;
  56
  57
  58 //---------------------------------------------------------
  59 // PertinentGraph
  60 // pertinent graph of a node in an SPQR-tree
  61 //---------------------------------------------------------
  62 //! Pertinent graphs of nodes in an SPQR-tree.
  63 /**
  64  * The class PertinentGraph represents the pertinent graph \a G(\a vT)
  65  * of a node \a vT in an SPQR-tree \a T with original graph \a G.
  66  *
  67  * The expansion graph E(\a e) of a virtual skeleton edge \a e is the skeleton graph
  68  * of the twin \a e' of \a e without \a e', where each virtual edge \a eV again is
  69  * replaced by its expansion graph E(\a eV). The pertinent graph \a G(\a vT) of a tree
  70  * node \a vT is obtained from the skeleton \a S of \a vT, where each edge except for
  71  * the reference edge of \a S is replaced by its expansion graph. Hence, if \a vT
  72  * is not the root node of \a T, all but one edge in \a G(\a vT) correspond to real
  73  * edges, otherwise all edges correspond to real edges.
  74  *
  75  * If \a P is the pertinent graph of a PlanarSPQRTree, the underlying graph
  76  * represents the combinatorial embedding which is implied by the embeddings
  77  * of the skeletons of \a T.
  78  */
  79
  80 class OGDF_EXPORT PertinentGraph
  81 {
  82         friend class OGDF_EXPORT SPQRTree;
  83
  84 public:
  85
  86         // constructor
  87         // Remark: Pertinent graphs are created by the pertinentGraph()
  88         //   function of SPQRTree.
  89
  90         //! Creates an empty instance of type PertinentGraph.
  91         /**
  92          * \remarks Pertinent graphs are created by the pertinentGraph()
  93          *          function of SPQRTree.
  94          */
  95         PertinentGraph() : m_vT(0) { }
  96
  97         //! Initialization of a pertinent graph of tree node \a vT.
  98         void init(node vT) {
  99                 m_P = Graph();
 100                 m_vT = vT;
 101                 m_vEdge = m_skRefEdge = 0;
 102                 m_origV.init(m_P,0);
 103                 m_origE.init(m_P,0);
 104         }
 105
 106
 107         //! Returns the tree node \a vT in \a T whose pertinent graph is this one.
 108         node treeNode() const {
 109                 return m_vT;
 110         }
 111
 112         //! Returns a reference to \a G(\a vT).
 113         const Graph &getGraph() const {
 114                 return m_P;
 115         }
 116
 117         //! Returns a reference to \a G(\a vT).
 118         Graph &getGraph() {
 119                 return m_P;
 120         }
 121
 122         //! Returns the edge in \a G(\a vT) corresponding to the reference edge in skeleton of \a vT.
 123         /**
 124          * If \a vT is the root of \a T, then 0 is returned.
 125          */
 126         edge referenceEdge() const {
 127                 return m_vEdge;
 128         }
 129
 130         //! Returns the reference edge in skeleton of \a vT.
 131         /**
 132          * Notice that this edge may differ from the current reference edge in skeleton
 133          * of \a vT if \a T has been rerooted after the construction of \a P.
 134          */
 135         edge skeletonReferenceEdge() const {
 136                 return m_skRefEdge;
 137         }
 138
 139         //! Returns the vertex in \a G that corresponds to \a v.
 140         /**
 141          * \pre \a v is a node in \a G(\a vT)
 142          */
 143         node original(node v) const {
 144                 return m_origV[v];
 145         }
 146
 147         //! Returns the edge in \a G that corresponds to \a e.
 148         /**
 149          * If \a e is the reference edge, then 0 is returned.
 150          * \pre \a e is an edge in \a G(\a vT)
 151          */
 152         edge original(edge e) const {
 153                 return m_origE[e];
 154         }
 155
 156 protected:
 157         node  m_vT;  //!< corresponding tree node
 158         Graph m_P;   //!< actual graph
 159         edge  m_vEdge; //!< reference edge (in \a m_P)
 160         edge  m_skRefEdge; //!< reference edge (in skeleton(\a m_vT))
 161
 162         NodeArray<node> m_origV; //!< corresp. original node
 163         EdgeArray<edge> m_origE; //!< corresp. original edge
 164 };
 165
 166
 167
 168 } // end namespace ogdf
 169
 170
 171 #endif