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// 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.
//
// ResetAndReturn(&cb) is like cb.Reset() but allows executing a callback (via a
// copy) after the original callback is Reset(). This can be handy if Run()
// reads/writes the variable holding the Callback.
#ifndef BASE_CALLBACK_HELPERS_H_
#define BASE_CALLBACK_HELPERS_H_
#include "base/callback.h"
#include "base/compiler_specific.h"
#include "base/macros.h"
namespace base {
template <typename Sig>
base::Callback<Sig> ResetAndReturn(base::Callback<Sig>* cb) {
base::Callback<Sig> ret(*cb);
cb->Reset();
return ret;
}
// 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(const Closure& 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(const Closure& closure);
// Releases the Closure without calling.
Closure Release() WARN_UNUSED_RESULT;
private:
Closure closure_;
DISALLOW_COPY_AND_ASSIGN(ScopedClosureRunner);
};
} // namespace base
#endif // BASE_CALLBACK_HELPERS_H_
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