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- /* 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 */
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