Index: media/base/callback_holder.h |
diff --git a/media/base/callback_holder.h b/media/base/callback_holder.h |
new file mode 100644 |
index 0000000000000000000000000000000000000000..6c827b3fbd7968b091825f73bb4ddec084a0e650 |
--- /dev/null |
+++ b/media/base/callback_holder.h |
@@ -0,0 +1,88 @@ |
+// Copyright (c) 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" |
+#include "media/base/bind_to_loop.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_|. |
+ // This method has overloaded versions to support different types of CB. |
+ void RunOrHold() { |
+ DCHECK(held_cb_.is_null()); |
+ if (hold_) |
+ held_cb_ = base::ResetAndReturn(&original_cb_); |
+ else |
+ base::ResetAndReturn(&original_cb_).Run(); |
+ } |
+ |
+ template <typename A1> void RunOrHold(A1 a1) { |
+ DCHECK(held_cb_.is_null()); |
+ if (hold_) { |
+ held_cb_ = base::Bind(base::ResetAndReturn(&original_cb_), |
+ internal::TrampolineForward(a1)); |
+ } else { |
+ base::ResetAndReturn(&original_cb_).Run(a1); |
+ } |
+ } |
+ |
+ template <typename A1, typename A2> void RunOrHold(A1 a1, A2 a2) { |
+ DCHECK(held_cb_.is_null()); |
+ if (hold_) { |
+ held_cb_ = base::Bind(base::ResetAndReturn(&original_cb_), |
+ internal::TrampolineForward(a1), |
+ internal::TrampolineForward(a2)); |
+ } else { |
+ base::ResetAndReturn(&original_cb_).Run(a1, a2); |
+ } |
+ } |
+ |
+ // 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::Closure held_cb_; |
+}; |
scherkus (not reviewing)
2013/05/28 15:56:57
DISALLOW ?
xhwang
2013/05/28 19:34:10
Done.
|
+ |
+} // namespace media |
+ |
+#endif // MEDIA_BASE_CALLBACK_HOLDER_H_ |