168 lines
5.9 KiB
C++
168 lines
5.9 KiB
C++
/*
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* Copyright (C) 2017 Apple Inc. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY APPLE INC. AND ITS CONTRIBUTORS ``AS IS''
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE INC. OR ITS CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
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* THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#pragma once
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#include <wtf/Function.h>
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#include <wtf/MainThread.h>
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namespace WTF {
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template<typename> class CompletionHandler;
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enum class CompletionHandlerCallThread { MainThread, ConstructionThread };
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// Wraps a Function to make sure it is always called once and only once.
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template <typename Out, typename... In>
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class CompletionHandler<Out(In...)> {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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CompletionHandler() = default;
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template<typename CallableType, class = typename std::enable_if<std::is_rvalue_reference<CallableType&&>::value>::type>
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CompletionHandler(CallableType&& callable, CompletionHandlerCallThread callThread = CompletionHandlerCallThread::ConstructionThread)
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: m_function(WTFMove(callable))
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#if ASSERT_ENABLED
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, m_shouldBeCalledOnMainThread(callThread == CompletionHandlerCallThread::MainThread || isMainThread())
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#endif
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{
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UNUSED_PARAM(callThread);
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}
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CompletionHandler(CompletionHandler&&) = default;
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CompletionHandler& operator=(CompletionHandler&&) = default;
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~CompletionHandler()
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{
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ASSERT_WITH_MESSAGE(!m_function, "Completion handler should always be called");
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}
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explicit operator bool() const { return !!m_function; }
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Out operator()(In... in)
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{
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ASSERT(m_shouldBeCalledOnMainThread == isMainThread());
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ASSERT_WITH_MESSAGE(m_function, "Completion handler should not be called more than once");
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return std::exchange(m_function, nullptr)(std::forward<In>(in)...);
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}
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private:
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Function<Out(In...)> m_function;
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#if ASSERT_ENABLED
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bool m_shouldBeCalledOnMainThread;
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#endif
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};
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// Wraps a Function to make sure it is called at most once.
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// If the CompletionHandlerWithFinalizer is destroyed and the function hasn't yet been called,
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// the finalizer is invoked with the function as its argument.
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template<typename> class CompletionHandlerWithFinalizer;
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template <typename Out, typename... In>
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class CompletionHandlerWithFinalizer<Out(In...)> {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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template<typename CallableType, class = typename std::enable_if<std::is_rvalue_reference<CallableType&&>::value>::type>
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CompletionHandlerWithFinalizer(CallableType&& callable, Function<void(Function<Out(In...)>&)>&& finalizer)
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: m_function(WTFMove(callable))
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, m_finalizer(WTFMove(finalizer))
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{
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}
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CompletionHandlerWithFinalizer(CompletionHandlerWithFinalizer&&) = default;
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CompletionHandlerWithFinalizer& operator=(CompletionHandlerWithFinalizer&&) = default;
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~CompletionHandlerWithFinalizer()
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{
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if (!m_function)
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return;
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m_finalizer(m_function);
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}
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explicit operator bool() const { return !!m_function; }
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Out operator()(In... in)
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{
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ASSERT(m_wasConstructedOnMainThread == isMainThread());
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ASSERT_WITH_MESSAGE(m_function, "Completion handler should not be called more than once");
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return std::exchange(m_function, nullptr)(std::forward<In>(in)...);
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}
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private:
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Function<Out(In...)> m_function;
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Function<void(Function<Out(In...)>&)> m_finalizer;
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#if ASSERT_ENABLED
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bool m_wasConstructedOnMainThread { isMainThread() };
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#endif
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};
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namespace Detail {
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template<typename Out, typename... In>
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class CallableWrapper<CompletionHandler<Out(In...)>, Out, In...> : public CallableWrapperBase<Out, In...> {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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explicit CallableWrapper(CompletionHandler<Out(In...)>&& completionHandler)
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: m_completionHandler(WTFMove(completionHandler))
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{
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RELEASE_ASSERT(m_completionHandler);
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}
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Out call(In... in) final { return m_completionHandler(std::forward<In>(in)...); }
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private:
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CompletionHandler<Out(In...)> m_completionHandler;
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};
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} // namespace Detail
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class CompletionHandlerCallingScope final {
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WTF_MAKE_FAST_ALLOCATED;
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public:
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CompletionHandlerCallingScope() = default;
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CompletionHandlerCallingScope(CompletionHandler<void()>&& completionHandler)
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: m_completionHandler(WTFMove(completionHandler))
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{ }
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~CompletionHandlerCallingScope()
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{
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if (m_completionHandler)
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m_completionHandler();
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}
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CompletionHandlerCallingScope(CompletionHandlerCallingScope&&) = default;
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CompletionHandlerCallingScope& operator=(CompletionHandlerCallingScope&&) = default;
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CompletionHandler<void()> release() { return WTFMove(m_completionHandler); }
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private:
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CompletionHandler<void()> m_completionHandler;
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};
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} // namespace WTF
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using WTF::CompletionHandler;
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using WTF::CompletionHandlerCallThread;
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using WTF::CompletionHandlerCallingScope;
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using WTF::CompletionHandlerWithFinalizer;
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