/usr/include/CGAL/Combination_enumerator.h is in libcgal-dev 4.2-5ubuntu1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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// Inria Nancy - Grand Est
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org); you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 3 of the License,
// or (at your option) any later version.
//
// Licensees holding a valid commercial license may use this file in
// accordance with the commercial license agreement provided with the software.
//
// This file is provided AS IS with NO WARRANTY OF ANY KIND, INCLUDING THE
// WARRANTY OF DESIGN, MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
//
// $URL$
// $Id$
//
// Author(s) : Samuel Hornus
#ifndef CGAL_COMBINATION_ENUMERATOR_H
#define CGAL_COMBINATION_ENUMERATOR_H
#include <CGAL/basic.h>
#include <vector>
namespace CGAL {
template< typename T >
class Combination_enumerator
{
// types and member data
typedef std::vector<T> Combination;
Combination combi_;
const int k_;
const T first_;
const T beyond_;
const T max_at_pos_0_;
// protected methods
const T & element(const int i) const
{
CGAL_assertion( 0 <= i && i < k_ );
return combi_[i];
}
T & element(const int i)
{
CGAL_assertion( 0 <= i && i < k_ );
return combi_[i];
}
public:
// For generating all the combinations of |k| distinct elements in the
// interval [first, beyond] (both included)
Combination_enumerator(const int k, const T & first, const T & beyond)
: combi_(k), k_(k), first_(first), beyond_(beyond), max_at_pos_0_(beyond - k)
{
CGAL_assertion_msg( (1 <= k) && (k <= beyond - first), "wrong value of k");
reset();
}
Combination_enumerator(const Combination_enumerator & c)
: combi_(c.combi_), k_(c.k_), first_(c.first_), beyond_(c.beyond_), max_at_pos_0_(c.max_at_pos_0_)
{}
int number_of_elements() const
{
return k_;
}
const T & min_element() const
{
return first_;
}
const T & beyond_element() const
{
return beyond_;
}
void reset()
{
T elem(min_element());
for( int i = 0; i < number_of_elements(); ++i )
{
element(i) = elem;
++elem;
}
}
bool finished() const
{
return max_at_pos_0_ < element(0);
}
const T & operator[](const int i) const
{
return element(i);
}
void operator++()
{
int i(k_ - 1);
T max_at_pos_i(beyond_-1);
while( ( i >= 0 ) && ( ! (element(i) < max_at_pos_i) ) )
{
--i;
--max_at_pos_i;
}
if( -1 == i )
{
if( element(0) == max_at_pos_0_ )
++element(0); // mark then end of the enumeration with an impossible value.
// Note than when we have arrived at the end of the enumeration, applying
// operator++() again does not change anything, so it is safe to
// apply it too many times.
}
else
{
++element(i);
for( int j = i + 1; j < k_; ++j )
element(j) = element(i) + (j - i);
}
}
Combination_enumerator operator++(int)
{
Combination_enumerator tmp(*this);
++(*this);
return tmp;
}
};
} // end of namespace CGAL
#endif // CGAL_COMBINATION_ENUMERATOR_H
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