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// 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 COBALT_MEDIA_BASE_CALLBACK_HOLDER_H_
#define COBALT_MEDIA_BASE_CALLBACK_HOLDER_H_
#include "base/bind.h"
#include "base/callback.h"
#include "base/callback_helpers.h"
#include "cobalt/media/base/bind_to_current_loop.h"
namespace cobalt {
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_;
};
} // namespace media
} // namespace cobalt
#endif // COBALT_MEDIA_BASE_CALLBACK_HOLDER_H_