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
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
|
#pragma once
#include <functional>
#include <memory>
#include <vector>
/**
* A class to be used to make sure some functions are called when the scope
* is left, because they will be called in the ScopeGuard's destructor. It
* can for example be used to delete some pointer whenever any exception is
* called. Example:
* {
* ScopeGuard scope;
* int* number = new int(2);
* scope.add_callback([number]() { delete number; });
* // Do some other stuff with the number. But these stuff might throw an exception:
* throw std::runtime_error("Some error not caught here, but in our caller");
* return true;
* }
* In this example, our pointer will always be deleted, even when the
* exception is thrown. If we want the functions to be called only when the
* scope is left because of an unexpected exception, we can use
* ScopeGuard::disable();
*/
namespace utils
{
class ScopeGuard
{
public:
/**
* The constructor can take a callback. But additional callbacks can be
* added later with add_callback()
*/
explicit ScopeGuard(std::function<void()>&& func):
enabled(true)
{
this->add_callback(std::move(func));
}
ScopeGuard(const ScopeGuard&) = delete;
ScopeGuard& operator=(ScopeGuard&&) = delete;
ScopeGuard(ScopeGuard&&) = delete;
ScopeGuard& operator=(const ScopeGuard&) = delete;
/**
* default constructor, the scope guard is enabled but empty, use
* add_callback()
*/
explicit ScopeGuard():
enabled(true)
{
}
/**
* Call all callbacks in the desctructor, unless it has been disabled.
*/
~ScopeGuard()
{
if (this->enabled)
for (auto& func: this->callbacks)
func();
}
/**
* Add a callback to be called in our destructor, one scope guard can be
* used for more than one task, if needed.
*/
void add_callback(std::function<void()>&& func)
{
this->callbacks.emplace_back(std::move(func));
}
/**
* Disable that scope guard, nothing will be done when the scope is
* exited.
*/
void disable()
{
this->enabled = false;
}
private:
bool enabled;
std::vector<std::function<void()>> callbacks;
};
template<typename F>
auto make_scope_guard(F f)
{
static struct Empty {} empty;
auto deleter = [f = std::move(f)](Empty*) { f(); };
return std::unique_ptr<Empty, decltype(deleter)>{&empty, std::move(deleter)};
}
}
|
