70 lines
1.8 KiB
C++
70 lines
1.8 KiB
C++
// Copyright (c) 2011 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 BASE_BIND_HELPERS_H_
|
|
#define BASE_BIND_HELPERS_H_
|
|
|
|
#include <stddef.h>
|
|
|
|
#include <type_traits>
|
|
#include <utility>
|
|
|
|
#include "base/bind.h"
|
|
#include "base/callback.h"
|
|
#include "base/memory/weak_ptr.h"
|
|
#include "build/build_config.h"
|
|
|
|
// This defines a set of simple functions and utilities that people want when
|
|
// using {Once,Repeating}Callback<> and Bind{Once,Repeating}().
|
|
|
|
namespace base {
|
|
|
|
// Creates a null callback.
|
|
class BASE_EXPORT NullCallback {
|
|
public:
|
|
template <typename R, typename... Args>
|
|
operator RepeatingCallback<R(Args...)>() const {
|
|
return RepeatingCallback<R(Args...)>();
|
|
}
|
|
template <typename R, typename... Args>
|
|
operator OnceCallback<R(Args...)>() const {
|
|
return OnceCallback<R(Args...)>();
|
|
}
|
|
};
|
|
|
|
// Creates a callback that does nothing when called.
|
|
class BASE_EXPORT DoNothing {
|
|
public:
|
|
template <typename... Args>
|
|
operator RepeatingCallback<void(Args...)>() const {
|
|
return Repeatedly<Args...>();
|
|
}
|
|
template <typename... Args>
|
|
operator OnceCallback<void(Args...)>() const {
|
|
return Once<Args...>();
|
|
}
|
|
// Explicit way of specifying a specific callback type when the compiler can't
|
|
// deduce it.
|
|
template <typename... Args>
|
|
static RepeatingCallback<void(Args...)> Repeatedly() {
|
|
return BindRepeating([](Args... args) {});
|
|
}
|
|
template <typename... Args>
|
|
static OnceCallback<void(Args...)> Once() {
|
|
return BindOnce([](Args... args) {});
|
|
}
|
|
};
|
|
|
|
// Useful for creating a Closure that will delete a pointer when invoked. Only
|
|
// use this when necessary. In most cases MessageLoop::DeleteSoon() is a better
|
|
// fit.
|
|
template <typename T>
|
|
void DeletePointer(T* obj) {
|
|
delete obj;
|
|
}
|
|
|
|
} // namespace base
|
|
|
|
#endif // BASE_BIND_HELPERS_H_
|