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1 // Copyright (c) 2013 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. | |
4 | |
5 #ifndef MEDIA_BASE_CALLBACK_HOLDER_H_ | |
6 #define MEDIA_BASE_CALLBACK_HOLDER_H_ | |
7 | |
8 #include "base/bind.h" | |
9 #include "base/callback.h" | |
10 #include "base/callback_helpers.h" | |
11 #include "media/base/bind_to_loop.h" | |
12 | |
13 namespace media { | |
14 | |
15 // A helper class that can hold a callback from being fired. | |
16 template <typename CB> class CallbackHolder { | |
17 public: | |
18 CallbackHolder() : hold_(false) {} | |
19 | |
20 ~CallbackHolder() { | |
21 // Make sure all callbacks are satisfied! | |
22 DCHECK(!hold_); | |
23 DCHECK(original_cb_.is_null()); | |
24 DCHECK(held_cb_.is_null()); | |
25 } | |
26 | |
27 // Sets the callback to be potentially held. | |
28 void SetCallback(const CB& cb) { | |
29 DCHECK(original_cb_.is_null()); | |
30 DCHECK(held_cb_.is_null()); | |
31 original_cb_ = cb; | |
32 } | |
33 | |
34 bool IsNull() const { | |
35 return original_cb_.is_null() && held_cb_.is_null(); | |
36 } | |
37 | |
38 // Holds the callback when Run() is called. | |
39 void HoldCallback() { hold_ = true; } | |
40 | |
41 // Runs or holds the callback as specified by |hold_|. | |
42 // This method has overloaded versions to support different types of CB. | |
43 void RunOrHold() { | |
44 DCHECK(held_cb_.is_null()); | |
45 if (hold_) | |
46 held_cb_ = base::ResetAndReturn(&original_cb_); | |
47 else | |
48 base::ResetAndReturn(&original_cb_).Run(); | |
49 } | |
50 | |
51 template <typename A1> void RunOrHold(A1 a1) { | |
52 DCHECK(held_cb_.is_null()); | |
53 if (hold_) { | |
54 held_cb_ = base::Bind(base::ResetAndReturn(&original_cb_), | |
55 internal::TrampolineForward(a1)); | |
56 } else { | |
57 base::ResetAndReturn(&original_cb_).Run(a1); | |
58 } | |
59 } | |
60 | |
61 template <typename A1, typename A2> void RunOrHold(A1 a1, A2 a2) { | |
62 DCHECK(held_cb_.is_null()); | |
63 if (hold_) { | |
64 held_cb_ = base::Bind(base::ResetAndReturn(&original_cb_), | |
65 internal::TrampolineForward(a1), | |
66 internal::TrampolineForward(a2)); | |
67 } else { | |
68 base::ResetAndReturn(&original_cb_).Run(a1, a2); | |
69 } | |
70 } | |
71 | |
72 // Releases and runs the held callback. | |
73 void RunHeldCallback() { | |
74 DCHECK(hold_); | |
75 DCHECK(!held_cb_.is_null()); | |
76 hold_ = false; | |
77 base::ResetAndReturn(&held_cb_).Run(); | |
78 } | |
79 | |
80 private: | |
81 bool hold_; | |
82 CB original_cb_; | |
83 base::Closure held_cb_; | |
84 }; | |
scherkus (not reviewing)
2013/05/28 15:56:57
DISALLOW ?
xhwang
2013/05/28 19:34:10
Done.
| |
85 | |
86 } // namespace media | |
87 | |
88 #endif // MEDIA_BASE_CALLBACK_HOLDER_H_ | |
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