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88 lines
2.6 KiB
88 lines
2.6 KiB
/*=========================================================================
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Program: CMake - Cross-Platform Makefile Generator
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Module: $RCSfile: cmComputeComponentGraph.h,v $
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Language: C++
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Date: $Date: 2008-02-07 21:14:05 $
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Version: $Revision: 1.1 $
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Copyright (c) 2002 Kitware, Inc., Insight Consortium. All rights reserved.
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See Copyright.txt or http://www.cmake.org/HTML/Copyright.html for details.
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This software is distributed WITHOUT ANY WARRANTY; without even
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the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
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PURPOSE. See the above copyright notices for more information.
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=========================================================================*/
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#ifndef cmComputeComponentGraph_h
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#define cmComputeComponentGraph_h
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#include "cmStandardIncludes.h"
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#include "cmGraphAdjacencyList.h"
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#include <stack>
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/** \class cmComputeComponentGraph
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* \brief Analyze a graph to determine strongly connected components.
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*
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* Convert a directed graph into a directed acyclic graph whose nodes
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* correspond to strongly connected components of the original graph.
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*
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* We use Tarjan's algorithm to enumerate the components efficiently.
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* An advantage of this approach is that the components are identified
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* in a topologically sorted order.
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*/
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class cmComputeComponentGraph
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{
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public:
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// Represent the graph with an adjacency list.
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typedef cmGraphNodeList NodeList;
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typedef cmGraphAdjacencyList Graph;
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cmComputeComponentGraph(Graph const& input);
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~cmComputeComponentGraph();
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/** Get the adjacency list of the component graph. */
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Graph const& GetComponentGraph() const
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{ return this->ComponentGraph; }
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NodeList const& GetComponentGraphEdges(int c) const
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{ return this->ComponentGraph[c]; }
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/** Get map from component index to original node indices. */
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std::vector<NodeList> const& GetComponents() const
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{ return this->Components; }
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NodeList const& GetComponent(int c) const
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{ return this->Components[c]; }
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/** Get map from original node index to component index. */
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std::vector<int> const& GetComponentMap() const
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{ return this->TarjanComponents; }
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private:
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void TransferEdges();
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Graph const& InputGraph;
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Graph ComponentGraph;
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// Tarjan's algorithm.
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struct TarjanEntry
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{
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int Root;
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int VisitIndex;
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};
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int TarjanWalkId;
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std::vector<int> TarjanVisited;
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std::vector<int> TarjanComponents;
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std::vector<TarjanEntry> TarjanEntries;
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std::stack<int> TarjanStack;
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int TarjanIndex;
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void Tarjan();
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void TarjanVisit(int i);
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// Connected components.
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std::vector<NodeList> Components;
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};
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#endif
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