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
|
/* Copyright (c) 1997-2024
Ewgenij Gawrilow, Michael Joswig, and the polymake team
Technische Universität Berlin, Germany
https://polymake.org
This program is free software; you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation; either version 2, or (at your option) any
later version: http://www.gnu.org/licenses/gpl.txt.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
--------------------------------------------------------------------------------
*/
#pragma once
#include "polymake/internal/iterators.h"
#include "polymake/Integer.h"
namespace pm {
template <typename Number = Int> class FibonacciNumbers;
// An infinite source of Fibonacci numbers - as iterator
template <typename Number = Int>
class Fibonacci_iterator {
public:
typedef forward_iterator_tag iterator_category;
typedef Number value_type;
typedef const Number& reference;
typedef const Number* pointer;
typedef ptrdiff_t difference_type;
typedef Fibonacci_iterator iterator;
typedef iterator const_iterator;
Fibonacci_iterator() : prev(0), cur(1) { }
explicit Fibonacci_iterator(unsigned long start_index)
{
if (start_index == 0) {
rewind();
} else {
const auto start = Integer::fibonacci2(start_index);
cur = static_cast<Number>(start.first);
prev = static_cast<Number>(start.second);
}
}
reference operator* () const { return cur; }
pointer operator-> () const { return &cur; }
iterator& operator++ () { const Number p = prev; prev = cur; cur += p; return *this; }
const iterator operator++ (int) { iterator copy(*this); operator++(); return copy; }
bool operator== (const iterator& it) const { return cur == it.cur; }
bool operator!= (const iterator& it) const { return !operator==(it); }
void rewind() { prev = 0; cur = 1; }
protected:
Number prev, cur;
Fibonacci_iterator(bool at_end) : prev(0), cur(0) { }
friend class FibonacciNumbers<Number>;
};
// An infinite source of Fibonacci numbers - as container
template <typename Number>
class FibonacciNumbers {
public:
typedef Number value_type;
typedef const Number& reference;
typedef reference const_reference;
typedef Fibonacci_iterator<Number> iterator;
typedef iterator const_iterator;
iterator begin() const { return iterator(); }
iterator end() const { return iterator(true); }
reference front() const { return one_value<Number>(); }
Int size() const { return std::numeric_limits<Int>::max(); }
bool empty() const { return false; }
};
template <typename Number>
struct check_iterator_feature<Fibonacci_iterator<Number>, unlimited> : std::true_type { };
template <typename Number>
struct check_iterator_feature<Fibonacci_iterator<Number>, rewindable> : std::true_type { };
template <typename Number>
struct spec_object_traits< FibonacciNumbers<Number> > : spec_object_traits<is_container> { };
template <typename Number = Int>
Fibonacci_iterator<Number> fibonacci_numbers() { return Fibonacci_iterator<Number>(); }
}
namespace polymake {
using pm::Fibonacci_iterator;
using pm::FibonacciNumbers;
using pm::fibonacci_numbers;
}
// Local Variables:
// mode:C++
// c-basic-offset:3
// indent-tabs-mode:nil
// End:
|
