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
|
/* A safe iterator for GDB, the GNU debugger.
Copyright (C) 2018-2022 Free Software Foundation, Inc.
This file is part of GDB.
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 3 of the License, or
(at your option) any later version.
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, see <http://www.gnu.org/licenses/>. */
#ifndef COMMON_SAFE_ITERATOR_H
#define COMMON_SAFE_ITERATOR_H
/* A forward iterator that wraps Iterator, such that when iterating
with iterator IT, it is possible to delete *IT without invalidating
IT. Suitably wrapped in a range type and used with range-for, this
allow convenient patterns like this:
// range_safe() returns a range type whose begin()/end() methods
// return safe iterators.
for (foo *f : range_safe ())
{
if (f->should_delete ())
{
// The ++it operation implicitly done by the range-for is
// still OK after this.
delete f;
}
}
*/
template<typename Iterator>
class basic_safe_iterator
{
public:
typedef basic_safe_iterator self_type;
typedef typename Iterator::value_type value_type;
typedef typename Iterator::reference reference;
typedef typename Iterator::pointer pointer;
typedef typename Iterator::iterator_category iterator_category;
typedef typename Iterator::difference_type difference_type;
/* Construct the begin iterator using the given arguments; the end iterator is
default constructed. */
template<typename... Args>
explicit basic_safe_iterator (Args &&...args)
: m_it (std::forward<Args> (args)...),
m_next (m_it)
{
if (m_it != m_end)
++m_next;
}
/* Construct the iterator using the first argument, and construct
the end iterator using the second argument. */
template<typename Arg>
explicit basic_safe_iterator (Arg &&arg, Arg &&arg2)
: m_it (std::forward<Arg> (arg)),
m_next (m_it),
m_end (std::forward<Arg> (arg2))
{
if (m_it != m_end)
++m_next;
}
/* Create a one-past-end iterator. */
basic_safe_iterator ()
{}
value_type operator* () const { return *m_it; }
self_type &operator++ ()
{
m_it = m_next;
if (m_it != m_end)
++m_next;
return *this;
}
bool operator== (const self_type &other) const
{ return m_it == other.m_it; }
bool operator!= (const self_type &other) const
{ return m_it != other.m_it; }
private:
/* The current element. */
Iterator m_it {};
/* The next element. Always one element ahead of M_IT. */
Iterator m_next {};
/* A one-past-end iterator. */
Iterator m_end {};
};
/* A range adapter that wraps another range, and then returns safe
iterators wrapping the original range's iterators. */
template<typename Range>
class basic_safe_range
{
public:
typedef basic_safe_iterator<typename Range::iterator> iterator;
explicit basic_safe_range (Range range)
: m_range (range)
{
}
iterator begin ()
{
return iterator (m_range.begin (), m_range.end ());
}
iterator end ()
{
return iterator (m_range.end (), m_range.end ());
}
private:
Range m_range;
};
#endif /* COMMON_SAFE_ITERATOR_H */
|
