| 1 | /* A safe iterator for GDB, the GNU debugger. |
| 2 | Copyright (C) 2018-2021 Free Software Foundation, Inc. |
| 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 | |
| 19 | #ifndef COMMON_SAFE_ITERATOR_H |
| 20 | #define COMMON_SAFE_ITERATOR_H |
| 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 | |
| 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)), |
| 56 | m_next (m_it) |
| 57 | { |
| 58 | if (m_it != m_end) |
| 59 | ++m_next; |
| 60 | } |
| 61 | |
| 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 | |
| 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 | |
| 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 | |
| 120 | iterator begin () |
| 121 | { |
| 122 | return iterator (m_range.begin (), m_range.end ()); |
| 123 | } |
| 124 | |
| 125 | iterator end () |
| 126 | { |
| 127 | return iterator (m_range.end (), m_range.end ()); |
| 128 | } |
| 129 | |
| 130 | private: |
| 131 | |
| 132 | Range m_range; |
| 133 | }; |
| 134 | |
| 135 | #endif /* COMMON_SAFE_ITERATOR_H */ |