1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
|
// Copyright (c) 2006-2009 Max-Planck-Institute Saarbruecken (Germany).
// 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: svn+ssh://scm.gforge.inria.fr/svn/cgal/branches/next/Algebraic_kernel_d/include/CGAL/Algebraic_kernel_d/Shear_controller.h $
// $Id: Shear_controller.h 67093 2012-01-13 11:22:39Z lrineau $
//
//
// Author(s) : Michael Kerber <mkerber@mpi-inf.mpg.de>
//
// ============================================================================
#ifndef CGAL_ACK_SHEAR_CONTROLLER
#define CGAL_ACK_SHEAR_CONTROLLER 1
#include <CGAL/basic.h>
#include<set>
namespace CGAL {
namespace internal {
/*!
* \brief A class that controls the used shear factors
*
* The objects returns positive integers that are used as shear factors.
* It choses integers from the range \c 1..max at random ,
* where \c c is a positive integer
* initially set in the constructor (8 by default). No integer is given
* twice by \c get_shear_factor(), at least if the failed ones are reported
* with the \c report_failure() method.
* If more than half of the integers in the range were bad, the range is
* enlarged to \c 1..2*max.
*/
template<typename Int,int InitialMax=8>
class Shear_controller {
public:
//! Constructor, getting the maximal absolute value of the shear factor
Shear_controller()
: m_max(InitialMax)
, pos_next_factor(0) {
CGAL_assertion(m_max>=1);
#if CGAL_ACK_STATIC_SEED
#warning Warning, uses static seed!
srand(CGAL_ACK_STATIC_SEED);
#else
srand(time(NULL));
#endif
}
//! Reports that the shear factor \c factor was bad.
void report_failure(Int factor) {
this->bad_shears.insert(factor);
long failures=static_cast<long>(this->bad_shears.size())+1;
if(2*failures>this->m_max) {
this->m_max*=2;
}
}
//! Gets a shear factor
Int get_shear_factor() {
if(pos_next_factor==static_cast<int>(value_order().size())) {
value_order().push_back(get_new_shear_factor());
}
return value_order()[pos_next_factor++];
}
private:
//! Gets a new shear factor
Int get_new_shear_factor() {
CGAL_assertion(int(this->bad_shears.size())<m_max);
while(true) {
Int s = Int(rand()%m_max)+1;
if(bad_shears.find(s)==bad_shears.end()) {
return s;
}
}
}
// Maximal absolute value
Int m_max;
static std::vector<Int>& value_order() {
static std::vector<Int> value_order_;
return value_order_;
}
int pos_next_factor;
// Unsuccessfull shear factors
std::set<Int> bad_shears;
};
} // namespace internal
} //namespace CGAL
#endif // CGAL_ACK_SHEAR_CONTROLLER
|
