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128 lines
3.6 KiB
C++
128 lines
3.6 KiB
C++
/*=========================================================================
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Program: Visualization Toolkit
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Module: vtkDirectedAcyclicGraph.cxx
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Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
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All rights reserved.
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See Copyright.txt or http://www.kitware.com/Copyright.htm 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 notice for more information.
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=========================================================================*/
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/*-------------------------------------------------------------------------
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Copyright 2008 Sandia Corporation.
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Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
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the U.S. Government retains certain rights in this software.
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-------------------------------------------------------------------------*/
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#include "vtkDirectedAcyclicGraph.h"
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#include "vtkInformation.h"
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#include "vtkInformationVector.h"
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#include "vtkObjectFactory.h"
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#include "vtkOutEdgeIterator.h"
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#include "vtkSmartPointer.h"
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#include <vector>
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vtkStandardNewMacro(vtkDirectedAcyclicGraph);
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//----------------------------------------------------------------------------
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vtkDirectedAcyclicGraph::vtkDirectedAcyclicGraph()
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{
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}
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//----------------------------------------------------------------------------
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vtkDirectedAcyclicGraph::~vtkDirectedAcyclicGraph()
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{
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}
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//----------------------------------------------------------------------------
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vtkDirectedAcyclicGraph *vtkDirectedAcyclicGraph::GetData(vtkInformation *info)
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{
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return info? vtkDirectedAcyclicGraph::SafeDownCast(info->Get(DATA_OBJECT())) : 0;
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}
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//----------------------------------------------------------------------------
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vtkDirectedAcyclicGraph *vtkDirectedAcyclicGraph::GetData(vtkInformationVector *v, int i)
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{
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return vtkDirectedAcyclicGraph::GetData(v->GetInformationObject(i));
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}
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enum { DFS_WHITE, DFS_GRAY, DFS_BLACK };
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//----------------------------------------------------------------------------
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static bool vtkDirectedAcyclicGraphDFSVisit(
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vtkGraph *g,
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vtkIdType u,
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std::vector<int> color,
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vtkOutEdgeIterator *adj)
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{
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color[u] = DFS_GRAY;
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g->GetOutEdges(u, adj);
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while (adj->HasNext())
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{
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vtkOutEdgeType e = adj->Next();
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vtkIdType v = e.Target;
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if (color[v] == DFS_WHITE)
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{
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if (!vtkDirectedAcyclicGraphDFSVisit(g, v, color, adj))
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{
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return false;
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}
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}
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else if (color[v] == DFS_GRAY)
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{
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return false;
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}
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}
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return true;
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}
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//----------------------------------------------------------------------------
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bool vtkDirectedAcyclicGraph::IsStructureValid(vtkGraph *g)
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{
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if (!g)
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{
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return false;
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}
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if (vtkDirectedAcyclicGraph::SafeDownCast(g))
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{
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return true;
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}
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// Empty graph is a valid DAG.
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if (g->GetNumberOfVertices() == 0)
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{
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return true;
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}
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// A directed graph is acyclic iff a depth-first search of
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// the graph yields no back edges.
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// (from Introduction to Algorithms.
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// Cormen, Leiserson, Rivest, p. 486).
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vtkIdType numVerts = g->GetNumberOfVertices();
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std::vector<int> color(numVerts, DFS_WHITE);
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vtkSmartPointer<vtkOutEdgeIterator> adj =
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vtkSmartPointer<vtkOutEdgeIterator>::New();
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for (vtkIdType s = 0; s < numVerts; ++s)
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{
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if (color[s] == DFS_WHITE)
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{
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if (!vtkDirectedAcyclicGraphDFSVisit(g, s, color, adj))
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{
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return false;
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}
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}
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}
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return true;
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}
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//----------------------------------------------------------------------------
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void vtkDirectedAcyclicGraph::PrintSelf(ostream& os, vtkIndent indent)
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{
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this->Superclass::PrintSelf(os,indent);
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}
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