blob: 0ab0af7bb21267975270888f9702a2272df0c9e8 (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
|
// Copyright (c) 2011 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#ifndef BASE_AUTO_RESET_H_
#define BASE_AUTO_RESET_H_
#include <utility>
#include "base/macros.h"
// base::AutoReset<> is useful for setting a variable to a new value only within
// a particular scope. An base::AutoReset<> object resets a variable to its
// original value upon destruction, making it an alternative to writing
// "var = false;" or "var = old_val;" at all of a block's exit points.
//
// This should be obvious, but note that an base::AutoReset<> instance should
// have a shorter lifetime than its scoped_variable, to prevent invalid memory
// writes when the base::AutoReset<> object is destroyed.
namespace base {
template<typename T>
class AutoReset {
public:
AutoReset(T* scoped_variable, T new_value)
: scoped_variable_(scoped_variable),
original_value_(std::move(*scoped_variable)) {
*scoped_variable_ = std::move(new_value);
}
AutoReset(AutoReset&& other)
: scoped_variable_(other.scoped_variable_),
original_value_(std::move(other.original_value_)) {
other.scoped_variable_ = nullptr;
}
~AutoReset() {
if (scoped_variable_)
*scoped_variable_ = std::move(original_value_);
}
AutoReset& operator=(AutoReset&& rhs) {
if (this != &rhs) {
scoped_variable_ = rhs.scoped_variable_;
rhs.scoped_variable_ = nullptr;
original_value_ = std::move(rhs.original_value_);
}
return *this;
}
private:
T* scoped_variable_;
T original_value_;
DISALLOW_COPY_AND_ASSIGN(AutoReset);
};
} // namespace base
#endif // BASE_AUTO_RESET_H_
|
