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08036331 | 1 | /* A safe iterator for GDB, the GNU debugger. |
b811d2c2 | 2 | Copyright (C) 2018-2020 Free Software Foundation, Inc. |
08036331 PA |
3 | |
4 | This file is part of GDB. | |
5 | ||
6 | This program is free software; you can redistribute it and/or modify | |
7 | it under the terms of the GNU General Public License as published by | |
8 | the Free Software Foundation; either version 3 of the License, or | |
9 | (at your option) any later version. | |
10 | ||
11 | This program is distributed in the hope that it will be useful, | |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | GNU General Public License for more details. | |
15 | ||
16 | You should have received a copy of the GNU General Public License | |
17 | along with this program. If not, see <http://www.gnu.org/licenses/>. */ | |
18 | ||
1a5c2598 TT |
19 | #ifndef COMMON_SAFE_ITERATOR_H |
20 | #define COMMON_SAFE_ITERATOR_H | |
08036331 PA |
21 | |
22 | /* A forward iterator that wraps Iterator, such that when iterating | |
23 | with iterator IT, it is possible to delete *IT without invalidating | |
24 | IT. Suitably wrapped in a range type and used with range-for, this | |
25 | allow convenient patterns like this: | |
26 | ||
27 | // range_safe() returns a range type whose begin()/end() methods | |
28 | // return safe iterators. | |
29 | for (foo *f : range_safe ()) | |
30 | { | |
31 | if (f->should_delete ()) | |
32 | { | |
33 | // The ++it operation implicitly done by the range-for is | |
34 | // still OK after this. | |
35 | delete f; | |
36 | } | |
37 | } | |
38 | */ | |
39 | ||
40 | template<typename Iterator> | |
41 | class basic_safe_iterator | |
42 | { | |
43 | public: | |
44 | typedef basic_safe_iterator self_type; | |
45 | typedef typename Iterator::value_type value_type; | |
46 | typedef typename Iterator::reference reference; | |
47 | typedef typename Iterator::pointer pointer; | |
48 | typedef typename Iterator::iterator_category iterator_category; | |
49 | typedef typename Iterator::difference_type difference_type; | |
50 | ||
13bff726 TT |
51 | /* Construct using the given argument; the end iterator is default |
52 | constructed. */ | |
53 | template<typename Arg> | |
54 | explicit basic_safe_iterator (Arg &&arg) | |
55 | : m_it (std::forward<Arg> (arg)), | |
08036331 PA |
56 | m_next (m_it) |
57 | { | |
58 | if (m_it != m_end) | |
59 | ++m_next; | |
60 | } | |
61 | ||
13bff726 TT |
62 | /* Construct the iterator using the first argument, and construct |
63 | the end iterator using the second argument. */ | |
64 | template<typename Arg> | |
65 | explicit basic_safe_iterator (Arg &&arg, Arg &&arg2) | |
66 | : m_it (std::forward<Arg> (arg)), | |
67 | m_next (m_it), | |
68 | m_end (std::forward<Arg> (arg2)) | |
69 | { | |
70 | if (m_it != m_end) | |
71 | ++m_next; | |
72 | } | |
73 | ||
08036331 PA |
74 | /* Create a one-past-end iterator. */ |
75 | basic_safe_iterator () | |
76 | {} | |
77 | ||
78 | value_type operator* () const { return *m_it; } | |
79 | ||
80 | self_type &operator++ () | |
81 | { | |
82 | m_it = m_next; | |
83 | if (m_it != m_end) | |
84 | ++m_next; | |
85 | return *this; | |
86 | } | |
87 | ||
88 | bool operator== (const self_type &other) const | |
89 | { return m_it == other.m_it; } | |
90 | ||
91 | bool operator!= (const self_type &other) const | |
92 | { return m_it != other.m_it; } | |
93 | ||
94 | private: | |
95 | /* The current element. */ | |
96 | Iterator m_it {}; | |
97 | ||
98 | /* The next element. Always one element ahead of M_IT. */ | |
99 | Iterator m_next {}; | |
100 | ||
101 | /* A one-past-end iterator. */ | |
102 | Iterator m_end {}; | |
103 | }; | |
104 | ||
13bff726 TT |
105 | /* A range adapter that wraps another range, and then returns safe |
106 | iterators wrapping the original range's iterators. */ | |
107 | ||
108 | template<typename Range> | |
109 | class basic_safe_range | |
110 | { | |
111 | public: | |
112 | ||
113 | typedef basic_safe_iterator<typename Range::iterator> iterator; | |
114 | ||
115 | explicit basic_safe_range (Range range) | |
116 | : m_range (range) | |
117 | { | |
118 | } | |
119 | ||
a5513db2 | 120 | iterator begin () |
13bff726 TT |
121 | { |
122 | return iterator (m_range.begin (), m_range.end ()); | |
123 | } | |
124 | ||
a5513db2 | 125 | iterator end () |
13bff726 TT |
126 | { |
127 | return iterator (m_range.end (), m_range.end ()); | |
128 | } | |
129 | ||
130 | private: | |
131 | ||
132 | Range m_range; | |
133 | }; | |
134 | ||
1a5c2598 | 135 | #endif /* COMMON_SAFE_ITERATOR_H */ |