blob: 9af22059f90fa81c777d8a2f2725e18099bfe3c9 (
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
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
|
// Copyright 2013 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 MEDIA_BASE_CALLBACK_HOLDER_H_
#define MEDIA_BASE_CALLBACK_HOLDER_H_
#include "base/bind.h"
#include "base/callback.h"
#include "base/callback_helpers.h"
namespace media {
// A helper class that can hold a callback from being fired.
template <typename CB> class CallbackHolder {
public:
CallbackHolder() : hold_(false) {}
~CallbackHolder() {
// Make sure all callbacks are satisfied!
DCHECK(!hold_);
DCHECK(original_cb_.is_null());
DCHECK(held_cb_.is_null());
}
// Sets the callback to be potentially held.
void SetCallback(const CB& cb) {
DCHECK(original_cb_.is_null());
DCHECK(held_cb_.is_null());
original_cb_ = cb;
}
bool IsNull() const {
return original_cb_.is_null() && held_cb_.is_null();
}
// Holds the callback when Run() is called.
void HoldCallback() { hold_ = true; }
// Runs or holds the callback as specified by |hold_|.
void RunOrHold() {
DCHECK(held_cb_.is_null());
if (hold_)
held_cb_ = base::ResetAndReturn(&original_cb_);
else
base::ResetAndReturn(&original_cb_).Run();
}
template <typename... Args>
void RunOrHold(Args&&... args) {
DCHECK(held_cb_.is_null());
if (hold_) {
held_cb_ = base::BindOnce(base::ResetAndReturn(&original_cb_),
std::forward<Args>(args)...);
} else {
base::ResetAndReturn(&original_cb_).Run(std::forward<Args>(args)...);
}
}
// Releases and runs the held callback.
void RunHeldCallback() {
DCHECK(hold_);
DCHECK(!held_cb_.is_null());
hold_ = false;
base::ResetAndReturn(&held_cb_).Run();
}
private:
bool hold_;
CB original_cb_;
base::OnceClosure held_cb_;
};
} // namespace media
#endif // MEDIA_BASE_CALLBACK_HOLDER_H_
|
