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/*=========================================================================
Program: Visualization Toolkit
Module: vtkDirectedAcyclicGraph.cxx
Copyright (c) Ken Martin, Will Schroeder, Bill Lorensen
All rights reserved.
See Copyright.txt or http://www.kitware.com/Copyright.htm for details.
This software is distributed WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR
PURPOSE. See the above copyright notice for more information.
=========================================================================*/
/*-------------------------------------------------------------------------
Copyright 2008 Sandia Corporation.
Under the terms of Contract DE-AC04-94AL85000 with Sandia Corporation,
the U.S. Government retains certain rights in this software.
-------------------------------------------------------------------------*/
#include "vtkDirectedAcyclicGraph.h"
#include "vtkInformation.h"
#include "vtkInformationVector.h"
#include "vtkObjectFactory.h"
#include "vtkOutEdgeIterator.h"
#include "vtkSmartPointer.h"
#include <vtksys/stl/vector>
using vtksys_stl::vector;
vtkStandardNewMacro(vtkDirectedAcyclicGraph);
//----------------------------------------------------------------------------
vtkDirectedAcyclicGraph::vtkDirectedAcyclicGraph()
{
}
//----------------------------------------------------------------------------
vtkDirectedAcyclicGraph::~vtkDirectedAcyclicGraph()
{
}
//----------------------------------------------------------------------------
vtkDirectedAcyclicGraph *vtkDirectedAcyclicGraph::GetData(vtkInformation *info)
{
return info? vtkDirectedAcyclicGraph::SafeDownCast(info->Get(DATA_OBJECT())) : 0;
}
//----------------------------------------------------------------------------
vtkDirectedAcyclicGraph *vtkDirectedAcyclicGraph::GetData(vtkInformationVector *v, int i)
{
return vtkDirectedAcyclicGraph::GetData(v->GetInformationObject(i));
}
enum { DFS_WHITE, DFS_GRAY, DFS_BLACK };
//----------------------------------------------------------------------------
static bool vtkDirectedAcyclicGraphDFSVisit(
vtkGraph *g,
vtkIdType u,
vtksys_stl::vector<int> color,
vtkOutEdgeIterator *adj)
{
color[u] = DFS_GRAY;
g->GetOutEdges(u, adj);
while (adj->HasNext())
{
vtkOutEdgeType e = adj->Next();
vtkIdType v = e.Target;
if (color[v] == DFS_WHITE)
{
if (!vtkDirectedAcyclicGraphDFSVisit(g, v, color, adj))
{
return false;
}
}
else if (color[v] == DFS_GRAY)
{
return false;
}
}
return true;
}
//----------------------------------------------------------------------------
bool vtkDirectedAcyclicGraph::IsStructureValid(vtkGraph *g)
{
if (!g)
{
return false;
}
if (vtkDirectedAcyclicGraph::SafeDownCast(g))
{
return true;
}
// Empty graph is a valid DAG.
if (g->GetNumberOfVertices() == 0)
{
return true;
}
// A directed graph is acyclic iff a depth-first search of
// the graph yields no back edges.
// (from Introduction to Algorithms.
// Cormen, Leiserson, Rivest, p. 486).
vtkIdType numVerts = g->GetNumberOfVertices();
vector<int> color(numVerts, DFS_WHITE);
vtkSmartPointer<vtkOutEdgeIterator> adj =
vtkSmartPointer<vtkOutEdgeIterator>::New();
for (vtkIdType s = 0; s < numVerts; ++s)
{
if (color[s] == DFS_WHITE)
{
if (!vtkDirectedAcyclicGraphDFSVisit(g, s, color, adj))
{
return false;
}
}
}
return true;
}
//----------------------------------------------------------------------------
void vtkDirectedAcyclicGraph::PrintSelf(ostream& os, vtkIndent indent)
{
this->Superclass::PrintSelf(os,indent);
}
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