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- /* scoped_restore, a simple class for saving and restoring a value
- Copyright (C) 2016-2022 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_SCOPED_RESTORE_H
- #define COMMON_SCOPED_RESTORE_H
- /* Base class for scoped_restore_tmpl. */
- class scoped_restore_base
- {
- public:
- /* This informs the (scoped_restore_tmpl<T>) dtor that you no longer
- want the original value restored. */
- void release () const
- { m_saved_var = NULL; }
- protected:
- scoped_restore_base (void *saved_var)
- : m_saved_var (saved_var)
- {}
- /* The type-erased saved variable. This is here so that clients can
- call release() on a "scoped_restore" local, which is a typedef to
- a scoped_restore_base. See below. */
- mutable void *m_saved_var;
- };
- /* A convenience typedef. Users of make_scoped_restore declare the
- local RAII object as having this type. */
- typedef const scoped_restore_base &scoped_restore;
- /* An RAII-based object that saves a variable's value, and then
- restores it again when this object is destroyed. */
- template<typename T>
- class scoped_restore_tmpl : public scoped_restore_base
- {
- public:
- /* Create a new scoped_restore object that saves the current value
- of *VAR. *VAR will be restored when this scoped_restore object
- is destroyed. */
- scoped_restore_tmpl (T *var)
- : scoped_restore_base (var),
- m_saved_value (*var)
- {
- }
- /* Create a new scoped_restore object that saves the current value
- of *VAR, and sets *VAR to VALUE. *VAR will be restored when this
- scoped_restore object is destroyed. This is templated on T2 to
- allow passing VALUEs of types convertible to T.
- E.g.: T='base'; T2='derived'. */
- template <typename T2>
- scoped_restore_tmpl (T *var, T2 value)
- : scoped_restore_base (var),
- m_saved_value (*var)
- {
- *var = value;
- }
- scoped_restore_tmpl (const scoped_restore_tmpl<T> &other)
- : scoped_restore_base {other.m_saved_var},
- m_saved_value (other.m_saved_value)
- {
- other.m_saved_var = NULL;
- }
- ~scoped_restore_tmpl ()
- {
- if (saved_var () != NULL)
- *saved_var () = m_saved_value;
- }
- private:
- /* Return a pointer to the saved variable with its type
- restored. */
- T *saved_var ()
- { return static_cast<T *> (m_saved_var); }
- /* No need for this. It is intentionally not defined anywhere. */
- scoped_restore_tmpl &operator= (const scoped_restore_tmpl &);
- /* The saved value. */
- const T m_saved_value;
- };
- /* Make a scoped_restore. This is useful because it lets template
- argument deduction work. */
- template<typename T>
- scoped_restore_tmpl<T> make_scoped_restore (T *var)
- {
- return scoped_restore_tmpl<T> (var);
- }
- /* Make a scoped_restore. This is useful because it lets template
- argument deduction work. */
- template<typename T, typename T2>
- scoped_restore_tmpl<T> make_scoped_restore (T *var, T2 value)
- {
- return scoped_restore_tmpl<T> (var, value);
- }
- #endif /* COMMON_SCOPED_RESTORE_H */
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