1 /* scoped_restore, a simple class for saving and restoring a value
3 Copyright (C) 2016-2019 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 COMMON_SCOPED_RESTORE_H
21 #define COMMON_SCOPED_RESTORE_H
23 /* Base class for scoped_restore_tmpl. */
24 class scoped_restore_base
27 /* This informs the (scoped_restore_tmpl<T>) dtor that you no longer
28 want the original value restored. */
30 { m_saved_var
= NULL
; }
33 scoped_restore_base (void *saved_var
)
34 : m_saved_var (saved_var
)
37 /* The type-erased saved variable. This is here so that clients can
38 call release() on a "scoped_restore" local, which is a typedef to
39 a scoped_restore_base. See below. */
40 mutable void *m_saved_var
;
43 /* A convenience typedef. Users of make_scoped_restore declare the
44 local RAII object as having this type. */
45 typedef const scoped_restore_base
&scoped_restore
;
47 /* An RAII-based object that saves a variable's value, and then
48 restores it again when this object is destroyed. */
50 class scoped_restore_tmpl
: public scoped_restore_base
54 /* Create a new scoped_restore object that saves the current value
55 of *VAR. *VAR will be restored when this scoped_restore object
57 scoped_restore_tmpl (T
*var
)
58 : scoped_restore_base (var
),
63 /* Create a new scoped_restore object that saves the current value
64 of *VAR, and sets *VAR to VALUE. *VAR will be restored when this
65 scoped_restore object is destroyed. This is templated on T2 to
66 allow passing VALUEs of types convertible to T.
67 E.g.: T='base'; T2='derived'. */
68 template <typename T2
>
69 scoped_restore_tmpl (T
*var
, T2 value
)
70 : scoped_restore_base (var
),
76 scoped_restore_tmpl (const scoped_restore_tmpl
<T
> &other
)
77 : scoped_restore_base
{other
.m_saved_var
},
78 m_saved_value (other
.m_saved_value
)
80 other
.m_saved_var
= NULL
;
83 ~scoped_restore_tmpl ()
85 if (saved_var () != NULL
)
86 *saved_var () = m_saved_value
;
90 /* Return a pointer to the saved variable with its type
93 { return static_cast<T
*> (m_saved_var
); }
95 /* No need for this. It is intentionally not defined anywhere. */
96 scoped_restore_tmpl
&operator= (const scoped_restore_tmpl
&);
98 /* The saved value. */
99 const T m_saved_value
;
102 /* Make a scoped_restore. This is useful because it lets template
103 argument deduction work. */
105 scoped_restore_tmpl
<T
> make_scoped_restore (T
*var
)
107 return scoped_restore_tmpl
<T
> (var
);
110 /* Make a scoped_restore. This is useful because it lets template
111 argument deduction work. */
112 template<typename T
, typename T2
>
113 scoped_restore_tmpl
<T
> make_scoped_restore (T
*var
, T2 value
)
115 return scoped_restore_tmpl
<T
> (var
, value
);
118 #endif /* COMMON_SCOPED_RESTORE_H */
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