You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
105 lines
3.2 KiB
105 lines
3.2 KiB
// Copyright (c) 2012 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.
|
|
|
|
// This defines helpful methods for dealing with Callbacks. Because Callbacks
|
|
// are implemented using templates, with a class per callback signature, adding
|
|
// methods to Callback<> itself is unattractive (lots of extra code gets
|
|
// generated). Instead, consider adding methods here.
|
|
|
|
#ifndef BASE_CALLBACK_HELPERS_H_
|
|
#define BASE_CALLBACK_HELPERS_H_
|
|
|
|
#include <utility>
|
|
|
|
#include "base/atomicops.h"
|
|
#include "base/bind.h"
|
|
#include "base/callback.h"
|
|
#include "base/compiler_specific.h"
|
|
#include "base/macros.h"
|
|
#include "base/memory/ptr_util.h"
|
|
|
|
namespace base {
|
|
|
|
// Prefer std::move() over ResetAndReturn().
|
|
template <typename CallbackType>
|
|
CallbackType ResetAndReturn(CallbackType* cb) {
|
|
CallbackType ret(std::move(*cb));
|
|
DCHECK(!*cb);
|
|
return ret;
|
|
}
|
|
|
|
namespace internal {
|
|
|
|
template <typename... Args>
|
|
class AdaptCallbackForRepeatingHelper final {
|
|
public:
|
|
explicit AdaptCallbackForRepeatingHelper(OnceCallback<void(Args...)> callback)
|
|
: callback_(std::move(callback)) {
|
|
DCHECK(callback_);
|
|
}
|
|
|
|
void Run(Args... args) {
|
|
if (subtle::NoBarrier_AtomicExchange(&has_run_, 1))
|
|
return;
|
|
DCHECK(callback_);
|
|
std::move(callback_).Run(std::forward<Args>(args)...);
|
|
}
|
|
|
|
private:
|
|
volatile subtle::Atomic32 has_run_ = 0;
|
|
base::OnceCallback<void(Args...)> callback_;
|
|
|
|
DISALLOW_COPY_AND_ASSIGN(AdaptCallbackForRepeatingHelper);
|
|
};
|
|
|
|
} // namespace internal
|
|
|
|
// Wraps the given OnceCallback into a RepeatingCallback that relays its
|
|
// invocation to the original OnceCallback on the first invocation. The
|
|
// following invocations are just ignored.
|
|
//
|
|
// Note that this deliberately subverts the Once/Repeating paradigm of Callbacks
|
|
// but helps ease the migration from old-style Callbacks. Avoid if possible; use
|
|
// if necessary for migration. TODO(tzik): Remove it. https://crbug.com/730593
|
|
template <typename... Args>
|
|
RepeatingCallback<void(Args...)> AdaptCallbackForRepeating(
|
|
OnceCallback<void(Args...)> callback) {
|
|
using Helper = internal::AdaptCallbackForRepeatingHelper<Args...>;
|
|
return base::BindRepeating(&Helper::Run,
|
|
std::make_unique<Helper>(std::move(callback)));
|
|
}
|
|
|
|
// ScopedClosureRunner is akin to std::unique_ptr<> for Closures. It ensures
|
|
// that the Closure is executed no matter how the current scope exits.
|
|
class BASE_EXPORT ScopedClosureRunner {
|
|
public:
|
|
ScopedClosureRunner();
|
|
explicit ScopedClosureRunner(OnceClosure closure);
|
|
~ScopedClosureRunner();
|
|
|
|
ScopedClosureRunner(ScopedClosureRunner&& other);
|
|
|
|
// Releases the current closure if it's set and replaces it with the closure
|
|
// from |other|.
|
|
ScopedClosureRunner& operator=(ScopedClosureRunner&& other);
|
|
|
|
// Calls the current closure and resets it, so it wont be called again.
|
|
void RunAndReset();
|
|
|
|
// Replaces closure with the new one releasing the old one without calling it.
|
|
void ReplaceClosure(OnceClosure closure);
|
|
|
|
// Releases the Closure without calling.
|
|
OnceClosure Release() WARN_UNUSED_RESULT;
|
|
|
|
private:
|
|
OnceClosure closure_;
|
|
|
|
DISALLOW_COPY_AND_ASSIGN(ScopedClosureRunner);
|
|
};
|
|
|
|
} // namespace base
|
|
|
|
#endif // BASE_CALLBACK_HELPERS_H_
|