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
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
|
/*
Copyright (C) 2003-2006 Tommi Junttila
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License version 2
as published by the Free Software Foundation.
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.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA.
*/
/* FSF address fixed in the above notice on 1 Oct 2009 by Tamas Nepusz */
#ifndef BLISS_KQUEUE_HH
#define BLISS_KQUEUE_HH
#include "bliss_defs.hh"
#include <cstdlib> // malloc
namespace igraph {
/*
* A queue with fixed capacity
*/
template <class Type>
class KQueue
{
public:
KQueue();
~KQueue();
void init(const unsigned int k);
bool is_empty() const;
unsigned int size() const;
unsigned int capacity() const;
void clear();
Type front() const;
Type pop_front();
void push_front(Type e);
Type pop_back();
void push_back(Type e);
private:
Type *entries, *end;
Type *head, *tail;
};
template <class Type>
KQueue<Type>::KQueue()
{
entries = 0;
end = 0;
head = 0;
tail = 0;
}
template <class Type>
KQueue<Type>::~KQueue()
{
if(entries)
free(entries);
}
template <class Type>
void KQueue<Type>::init(const unsigned int k)
{
assert(k > 0);
if(entries)
free(entries);
entries = (Type*)malloc((k + 1) * sizeof(Type));
end = entries + k + 1;
head = entries;
tail = head;
}
template <class Type>
void KQueue<Type>::clear()
{
head = entries;
tail = head;
}
template <class Type>
bool KQueue<Type>::is_empty() const
{
return(head == tail);
}
template <class Type>
unsigned int KQueue<Type>::size() const
{
if(tail >= head)
return(tail - head);
return((end - head) + (tail - entries));
}
template <class Type>
Type KQueue<Type>::front() const
{
DEBUG_ASSERT(head != tail);
return *head;
}
template <class Type>
Type KQueue<Type>::pop_front()
{
DEBUG_ASSERT(head != tail);
Type *old_head = head;
head++;
if(head == end)
head = entries;
return *old_head;
}
template <class Type>
void KQueue<Type>::push_front(Type e)
{
if(head == entries)
head = end - 1;
else
head--;
DEBUG_ASSERT(head != tail);
*head = e;
}
template <class Type>
void KQueue<Type>::push_back(Type e)
{
*tail = e;
tail++;
if(tail == end)
tail = entries;
DEBUG_ASSERT(head != tail);
}
}
#endif
|
