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// Copyright (c) 2011 INRIA Sophia-Antipolis (France).
// All rights reserved.
//
// This file is part of CGAL (www.cgal.org)
//
// $URL: https://github.com/CGAL/cgal/blob/v6.1.1/Spatial_sorting/include/CGAL/Hilbert_sort_middle_d.h $
// $Id: include/CGAL/Hilbert_sort_middle_d.h 08b27d3db14 $
// SPDX-License-Identifier: LGPL-3.0-or-later OR LicenseRef-Commercial
//
// Author(s) : Olivier Devillers
#ifndef CGAL_HILBERT_SORT_MIDDLE_d_H
#define CGAL_HILBERT_SORT_MIDDLE_d_H
#include <CGAL/config.h>
#include <functional>
#include <cstddef>
#include <vector>
#include <CGAL/Hilbert_sort_middle_base.h>
namespace CGAL {
namespace internal {
template <class K>
struct Fixed_hilbert_cmp_d
: public CGAL::cpp98::binary_function<typename K::Point_d,
typename K::Point_d, bool>
{
typedef typename K::Point_d Point;
K k;
int axe;
bool orient;
double value;
Fixed_hilbert_cmp_d (int a, bool o, double v, const K &_k)
: k(_k), axe(a), orient(o), value(v) {}
bool operator() (const Point &p) const
{
return (orient
? ( to_double( k.compute_coordinate_d_object() (p,axe) ) > value)
: ( to_double( k.compute_coordinate_d_object() (p,axe) ) <= value));
}
};
}
template <class K>
class Hilbert_sort_middle_d
{
public:
typedef K Kernel;
typedef typename Kernel::Point_d Point;
typedef std::vector< bool > Starting_position;
typedef std::vector< double > Corner;
private:
Kernel _k;
std::ptrdiff_t _limit;
mutable int _dimension;
mutable int two_to_dim;
struct Cmp : public internal::Fixed_hilbert_cmp_d<Kernel>
{ Cmp (int a, bool dir, double v, const Kernel &k)
: internal::Fixed_hilbert_cmp_d<Kernel> (a,dir,v,k) {} };
public:
Hilbert_sort_middle_d (const Kernel &k, std::ptrdiff_t limit = 1)
: _k(k), _limit (limit)
{}
template <class RandomAccessIterator>
void sort (RandomAccessIterator begin, RandomAccessIterator end,
Starting_position start, int direction,
Corner mini, Corner maxi) const
{
if (end - begin <= _limit) return;
Corner med(_dimension);
for( int i=0; i<_dimension; ++i) med[i]=(mini[i]+maxi[i])/2;
Corner cmin=mini,cmax=med;
std::vector<RandomAccessIterator> places(two_to_dim +1);
std::vector<int> dir (two_to_dim +1);
places[0]=begin;
places[two_to_dim]=end;
int last_dir = (direction + _dimension) % _dimension;
int current_dir = direction;
int current_level_step =two_to_dim;
do{
int half_step = current_level_step/2;
int left=0;
int middle = half_step;
int right=current_level_step;
bool orient = start[current_dir];
do{
dir[middle] = current_dir;
places[middle] = internal::fixed_hilbert_split
(places[left], places[right],
Cmp (current_dir,orient,med[current_dir],_k));
left =right;
right+=current_level_step;
middle+=current_level_step;
orient = ! orient;
}while( left< two_to_dim);
current_level_step = half_step;
current_dir = (current_dir +1) % _dimension;
}while (current_dir != last_dir);
/////////////start recursive calls
last_dir = (direction + _dimension -1) % _dimension;
// first step is special
if (places[1]!=end)
sort( places[0], places[1], start, last_dir,cmin,cmax);
cmin[last_dir] = med[last_dir];
cmax[last_dir] = maxi[last_dir];
for(int i=1; i<two_to_dim-1; i +=2){
//std::cout<<i<<";"<<start[0]<<start[1]<<start[2]<<start[3]<<"/"<<dir[i+1]<<std::endl;
if (places[i]!=begin || places[i+1]!=end)
sort( places[i ], places[i+1], start, dir[i+1],cmin,cmax);
cmax[ dir[i+1] ] = (cmin[ dir[i+1]]==mini[ dir[i+1]])
? maxi[ dir[i+1] ] : mini[ dir[i+1] ];
cmin[ dir[i+1] ] = med[ dir[i+1] ];
if (places[i+1]!=begin || places[i+2]!=end)
sort( places[i+1], places[i+2], start, dir[i+1],cmin,cmax);
cmin[ dir[i+1] ] = cmax[ dir[i+1] ];
cmax[ dir[i+1] ] = med[ dir[i+1] ];
cmax[ last_dir ] = (cmax[last_dir]==maxi[last_dir])
? mini[ last_dir ] : maxi[ last_dir ];
start[dir[i+1]] = ! start[dir[i+1]];
start[last_dir] = ! start[last_dir];
}
//last step is special
if (places[two_to_dim-1]!=begin)
sort( places[two_to_dim-1], places[two_to_dim], start, last_dir,cmin,cmax);
}
template <class RandomAccessIterator>
void operator() (RandomAccessIterator begin, RandomAccessIterator end) const
{
_dimension = _k.point_dimension_d_object()(*begin);
two_to_dim = 1;
Starting_position start(_dimension);
Corner mini(_dimension),maxi(_dimension);
for (int i=0; i<_dimension; ++i)
mini[i]=maxi[i]=to_double( _k.compute_coordinate_d_object() (*begin,i) );
for(RandomAccessIterator it=begin+1; it<end; ++it){
for (int i=0; i<_dimension; ++i){
double d= to_double( _k.compute_coordinate_d_object() (*it,i) );
if (d < mini[i]) mini[i] = d;
if (d > maxi[i]) maxi[i] = d;
}
}
for (int i=0; i<_dimension; ++i) {
start[i]=false; // we start below in all coordinates
two_to_dim *= 2; // compute 2^_dimension
if (two_to_dim*2 <= 0) {
CGAL_assertion(end-begin < two_to_dim);//too many points in such dim
break;
}
}
// we start with direction 0;
sort (begin, end, start, 0, mini, maxi);
}
};
} // namespace CGAL
#endif//CGAL_HILBERT_SORT_MIDDLE_d_H
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