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