Commit | Line | Data |
---|---|---|
b7b633e9 TT |
1 | /* scoped_restore, a simple class for saving and restoring a value |
2 | ||
e2882c85 | 3 | Copyright (C) 2016-2018 Free Software Foundation, Inc. |
b7b633e9 TT |
4 | |
5 | This file is part of GDB. | |
6 | ||
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. | |
11 | ||
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. | |
16 | ||
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/>. */ | |
19 | ||
20 | #ifndef SCOPED_RESTORE_H | |
21 | #define SCOPED_RESTORE_H | |
22 | ||
23 | /* Base class for scoped_restore_tmpl. */ | |
9bcb1f16 | 24 | class scoped_restore_base |
b7b633e9 | 25 | { |
9bcb1f16 PA |
26 | public: |
27 | /* This informs the (scoped_restore_tmpl<T>) dtor that you no longer | |
28 | want the original value restored. */ | |
29 | void release () const | |
30 | { m_saved_var = NULL; } | |
31 | ||
32 | protected: | |
33 | scoped_restore_base (void *saved_var) | |
34 | : m_saved_var (saved_var) | |
35 | {} | |
36 | ||
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; | |
b7b633e9 TT |
41 | }; |
42 | ||
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; | |
46 | ||
47 | /* An RAII-based object that saves a variable's value, and then | |
48 | restores it again when this object is destroyed. */ | |
49 | template<typename T> | |
50 | class scoped_restore_tmpl : public scoped_restore_base | |
51 | { | |
52 | public: | |
53 | ||
54 | /* Create a new scoped_restore object that saves the current value | |
55 | of *VAR. *VAR will be restored when this scoped_restore object | |
56 | is destroyed. */ | |
57 | scoped_restore_tmpl (T *var) | |
9bcb1f16 | 58 | : scoped_restore_base (var), |
b7b633e9 TT |
59 | m_saved_value (*var) |
60 | { | |
61 | } | |
62 | ||
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 | |
60adb36c PA |
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) | |
9bcb1f16 | 70 | : scoped_restore_base (var), |
b7b633e9 TT |
71 | m_saved_value (*var) |
72 | { | |
73 | *var = value; | |
74 | } | |
75 | ||
76 | scoped_restore_tmpl (const scoped_restore_tmpl<T> &other) | |
9bcb1f16 | 77 | : scoped_restore_base {other.m_saved_var}, |
b7b633e9 TT |
78 | m_saved_value (other.m_saved_value) |
79 | { | |
80 | other.m_saved_var = NULL; | |
81 | } | |
82 | ||
83 | ~scoped_restore_tmpl () | |
84 | { | |
9bcb1f16 PA |
85 | if (saved_var () != NULL) |
86 | *saved_var () = m_saved_value; | |
b7b633e9 TT |
87 | } |
88 | ||
9bcb1f16 PA |
89 | private: |
90 | /* Return a pointer to the saved variable with its type | |
91 | restored. */ | |
92 | T *saved_var () | |
93 | { return static_cast<T *> (m_saved_var); } | |
b7b633e9 TT |
94 | |
95 | /* No need for this. It is intentionally not defined anywhere. */ | |
96 | scoped_restore_tmpl &operator= (const scoped_restore_tmpl &); | |
97 | ||
b7b633e9 TT |
98 | /* The saved value. */ |
99 | const T m_saved_value; | |
100 | }; | |
101 | ||
102 | /* Make a scoped_restore. This is useful because it lets template | |
103 | argument deduction work. */ | |
104 | template<typename T> | |
105 | scoped_restore_tmpl<T> make_scoped_restore (T *var) | |
106 | { | |
107 | return scoped_restore_tmpl<T> (var); | |
108 | } | |
109 | ||
110 | /* Make a scoped_restore. This is useful because it lets template | |
111 | argument deduction work. */ | |
60adb36c PA |
112 | template<typename T, typename T2> |
113 | scoped_restore_tmpl<T> make_scoped_restore (T *var, T2 value) | |
b7b633e9 TT |
114 | { |
115 | return scoped_restore_tmpl<T> (var, value); | |
116 | } | |
117 | ||
118 | #endif /* SCOPED_RESTORE_H */ |