1 // Copyright (c) 2011 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
5 #ifndef BASE_AUTO_RESET_H_
6 #define BASE_AUTO_RESET_H_
10 // base::AutoReset<> is useful for setting a variable to a new value only within
11 // a particular scope. An base::AutoReset<> object resets a variable to its
12 // original value upon destruction, making it an alternative to writing
13 // "var = false;" or "var = old_val;" at all of a block's exit points.
15 // This should be obvious, but note that an base::AutoReset<> instance should
16 // have a shorter lifetime than its scoped_variable, to prevent invalid memory
17 // writes when the base::AutoReset<> object is destroyed.
25 AutoReset(T* scoped_variable, U&& new_value)
26 : scoped_variable_(scoped_variable),
28 std::exchange(*scoped_variable_, std::forward<U>(new_value))) {}
30 AutoReset(AutoReset&& other)
31 : scoped_variable_(std::exchange(other.scoped_variable_, nullptr)),
32 original_value_(std::move(other.original_value_)) {}
34 AutoReset& operator=(AutoReset&& rhs) {
35 scoped_variable_ = std::exchange(rhs.scoped_variable_, nullptr);
36 original_value_ = std::move(rhs.original_value_);
42 *scoped_variable_ = std::move(original_value_);
52 #endif // BASE_AUTO_RESET_H_