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