3 Copyright (C) 2017 Free Software Foundation, Inc.
5 This file is part of GDB.
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 3 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program. If not, see <http://www.gnu.org/licenses/>. */
20 #ifndef GDB_OPTIONAL_H
21 #define GDB_OPTIONAL_H
26 /* This class attempts to be a compatible subset of std::optional,
27 which is slated to be available in C++17. This class optionally
28 holds an object of some type -- by default it is constructed not
29 holding an object, but later the object can be "emplaced". This is
30 similar to using std::unique_ptr, but in-object allocation is
38 : m_instantiated (false)
48 /* These aren't deleted in std::optional, but it was simpler to
49 delete them here, because currently the users of this class don't
50 need them, and making them depend on the definition of T is
51 somewhat complicated. */
52 optional (const optional
&other
) = delete;
53 optional
<T
> &operator= (const optional
&other
) = delete;
55 template<typename
... Args
>
56 void emplace (Args
&&... args
)
60 new (&m_item
) T (std::forward
<Args
>(args
)...);
61 m_instantiated
= true;
66 /* Destroy the object. */
69 gdb_assert (m_instantiated
);
70 m_instantiated
= false;
81 /* True if the object was ever emplaced. */
87 #endif /* GDB_OPTIONAL_H */
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