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// Copyright (c) 1997
// Utrecht University (The Netherlands),
// ETH Zurich (Switzerland),
// INRIA Sophia-Antipolis (France),
// Max-Planck-Institute Saarbruecken (Germany),
// and Tel-Aviv University (Israel). All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/HalfedgeDS/include/CGAL/halfedgeds_connected_components.h $
// $Id: include/CGAL/halfedgeds_connected_components.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
//
// Author(s) : Lutz Kettner <kettner@mpi-sb.mpg.de>
#ifndef CGAL_HALFEDGEDS_CONNECTED_COMPONENTS_H
#define CGAL_HALFEDGEDS_CONNECTED_COMPONENTS_H 1
#include <CGAL/Unique_hash_map.h>
#include <CGAL/iterator.h>
#include <vector>
namespace CGAL {
template <class HDS, class Output_iterator,
class Halfedge_iterator, class Halfedge_handle>
std::size_t
halfedgeds_connected_components( HDS hds, Output_iterator result) {
Unique_hash_map< Halfedge_iterator, bool> hedge_map( false);
std::size_t count = 0;
std::vector< Halfedge_handle> hstack;
hstack.reserve( hds.size_of_halfedges() + 3/ 4);
Halfedge_iterator scan = hds.halfedges_begin();
while ( scan != hds.halfedges_end()) {
// first trace the component, then report it
hstack.clear();
hstack.push_back( scan);
while ( ! hstack.empty()) {
Halfedge_handle h = hstack.back();
hstack.pop_back();
if ( ! hedge_map[ h] ) {
hedge_map[ h] = true;
hstack.push_back( h->next());
hstack.push_back( h->opposite());
}
}
++count;
*result++ = scan;
while( hedge_map[ scan])
++scan;
}
return count;
}
template <class HDS, class Output_iterator>
std::size_t
halfedgeds_connected_components( HDS& hds, Output_iterator result) {
typedef typename HDS::Halfedge_iterator Halfedge_iterator;
typedef typename HDS::Halfedge_handle Halfedge_handle;
return halfedgeds_connected_components<HDS&, Output_iterator,
Halfedge_iterator, Halfedge_handle>( hds, result);
}
template <class HDS, class Output_iterator>
std::size_t
halfedgeds_connected_components( const HDS& hds, Output_iterator result) {
typedef typename HDS::Halfedge_const_iterator Halfedge_iterator;
typedef typename HDS::Halfedge_const_handle Halfedge_handle;
return halfedgeds_connected_components<const HDS&, Output_iterator,
Halfedge_iterator, Halfedge_handle>( hds, result);
}
template <class HDS>
std::size_t
halfedgeds_connected_components( HDS& hds) {
return halfedgeds_connected_components( hds, Emptyset_iterator());
}
} //namespace CGAL
#endif // CGAL_HALFEDGEDS_CONNECTED_COMPONENTS_H //
// EOF //
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