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| 1 // Copyright (c) 2015 The Chromium Authors. All rights reserved. | 1 // Copyright (c) 2015 The Chromium Authors. All rights reserved. |
| 2 // Use of this source code is governed by a BSD-style license that can be | 2 // Use of this source code is governed by a BSD-style license that can be |
| 3 // found in the LICENSE file. | 3 // found in the LICENSE file. |
| 4 | 4 |
| 5 #ifndef MEDIA_BASE_BIND_TO_CURRENT_LOOP_H_ | 5 #ifndef MEDIA_BASE_BIND_TO_CURRENT_LOOP_H_ |
| 6 #define MEDIA_BASE_BIND_TO_CURRENT_LOOP_H_ | 6 #define MEDIA_BASE_BIND_TO_CURRENT_LOOP_H_ |
| 7 | 7 |
| 8 #include "base/bind.h" | 8 #include "base/bind_to_task_runner.h" |
| 9 #include "base/location.h" | |
| 10 #include "base/memory/scoped_vector.h" | |
| 11 #include "base/single_thread_task_runner.h" | |
| 12 #include "base/thread_task_runner_handle.h" | |
| 13 | 9 |
| 14 // This is a helper utility for base::Bind()ing callbacks to the current | 10 // DEPRECATED. New code should use base::BindToCurrentThread() instead. |
| 15 // MessageLoop. The typical use is when |a| (of class |A|) wants to hand a | |
| 16 // callback such as base::Bind(&A::AMethod, a) to |b|, but needs to ensure that | |
| 17 // when |b| executes the callback, it does so on |a|'s current MessageLoop. | |
| 18 // | |
| 19 // Typical usage: request to be called back on the current thread: | |
| 20 // other->StartAsyncProcessAndCallMeBack( | |
| 21 // media::BindToCurrentLoop(base::Bind(&MyClass::MyMethod, this))); | |
| 22 // | |
| 23 // Note that like base::Bind(), BindToCurrentLoop() can't bind non-constant | |
| 24 // references, and that *unlike* base::Bind(), BindToCurrentLoop() makes copies | |
| 25 // of its arguments, and thus can't be used with arrays. | |
| 26 | 11 |
| 27 namespace media { | 12 namespace media { |
| 28 | 13 |
| 29 // Mimic base::internal::CallbackForward, replacing p.Pass() with | |
| 30 // base::Passed(&p) to account for the extra layer of indirection. | |
| 31 namespace internal { | |
| 32 template <typename T> | 14 template <typename T> |
| 33 T& TrampolineForward(T& t) { return t; } | 15 base::Callback<T> BindToCurrentLoop(const base::Callback<T>& cb) { |
| 34 | 16 return base::BindToCurrentThread(cb); |
| 35 template <typename T, typename R> | |
| 36 base::internal::PassedWrapper<scoped_ptr<T, R> > TrampolineForward( | |
| 37 scoped_ptr<T, R>& p) { return base::Passed(&p); } | |
| 38 | |
| 39 template <typename T> | |
| 40 base::internal::PassedWrapper<ScopedVector<T> > TrampolineForward( | |
| 41 ScopedVector<T>& p) { return base::Passed(&p); } | |
| 42 | |
| 43 // First, tell the compiler TrampolineHelper is a struct template with one | |
| 44 // type parameter. Then define specializations where the type is a function | |
| 45 // returning void and taking zero or more arguments. | |
| 46 template <typename Sig> struct TrampolineHelper; | |
| 47 | |
| 48 template <typename... Args> | |
| 49 struct TrampolineHelper<void(Args...)> { | |
| 50 static void Run( | |
| 51 const scoped_refptr<base::SingleThreadTaskRunner>& task_runner, | |
| 52 const base::Callback<void(Args...)>& cb, | |
| 53 Args... args) { | |
| 54 task_runner->PostTask(FROM_HERE, | |
| 55 base::Bind(cb, TrampolineForward(args)...)); | |
| 56 } | |
| 57 }; | |
| 58 | |
| 59 } // namespace internal | |
| 60 | |
| 61 template<typename T> | |
| 62 static base::Callback<T> BindToCurrentLoop( | |
| 63 const base::Callback<T>& cb) { | |
| 64 return base::Bind(&internal::TrampolineHelper<T>::Run, | |
| 65 base::ThreadTaskRunnerHandle::Get(), cb); | |
| 66 } | 17 } |
| 67 | 18 |
| 68 } // namespace media | 19 } // namespace media |
| 69 | 20 |
| 70 #endif // MEDIA_BASE_BIND_TO_CURRENT_LOOP_H_ | 21 #endif // MEDIA_BASE_BIND_TO_CURRENT_LOOP_H_ |
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