mirror of
https://github.com/SerenityOS/serenity
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a6e4482080
This commit makes the user-facing StdLibExtras templates and utilities arguably more nice-looking by removing the need to reach into the wrapper structs generated by them to get the value/type needed. The C++ standard library had to invent `_v` and `_t` variants (likely because of backwards compat), but we don't need to cater to any codebase except our own, so might as well have good things for free. :^)
123 lines
4.1 KiB
C++
123 lines
4.1 KiB
C++
/*
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* Copyright (C) 2016 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 <AK/Assertions.h>
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#include <AK/OwnPtr.h>
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#include <AK/StdLibExtras.h>
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namespace AK {
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template<typename>
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class Function;
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template<typename Out, typename... In>
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class Function<Out(In...)> {
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public:
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Function() = default;
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template<typename CallableType, class = typename EnableIf<!(IsPointer<CallableType> && IsFunction<RemovePointer<CallableType>>)&&IsRvalueReference<CallableType&&>>::Type>
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Function(CallableType&& callable)
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: m_callable_wrapper(make<CallableWrapper<CallableType>>(move(callable)))
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{
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}
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template<typename FunctionType, class = typename EnableIf<IsPointer<FunctionType> && IsFunction<RemovePointer<FunctionType>>>::Type>
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Function(FunctionType f)
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: m_callable_wrapper(make<CallableWrapper<FunctionType>>(move(f)))
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{
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}
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Out operator()(In... in) const
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{
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VERIFY(m_callable_wrapper);
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return m_callable_wrapper->call(forward<In>(in)...);
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}
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explicit operator bool() const { return !!m_callable_wrapper; }
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template<typename CallableType, class = typename EnableIf<!(IsPointer<CallableType> && IsFunction<RemovePointer<CallableType>>)&&IsRvalueReference<CallableType&&>>::Type>
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Function& operator=(CallableType&& callable)
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{
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m_callable_wrapper = make<CallableWrapper<CallableType>>(move(callable));
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return *this;
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}
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template<typename FunctionType, class = typename EnableIf<IsPointer<FunctionType> && IsFunction<RemovePointer<FunctionType>>>::Type>
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Function& operator=(FunctionType f)
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{
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m_callable_wrapper = make<CallableWrapper<FunctionType>>(move(f));
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return *this;
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}
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Function& operator=(std::nullptr_t)
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{
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m_callable_wrapper = nullptr;
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return *this;
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}
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private:
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class CallableWrapperBase {
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public:
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virtual ~CallableWrapperBase() = default;
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virtual Out call(In...) const = 0;
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};
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template<typename CallableType>
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class CallableWrapper final : public CallableWrapperBase {
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public:
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explicit CallableWrapper(CallableType&& callable)
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: m_callable(move(callable))
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{
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}
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CallableWrapper(const CallableWrapper&) = delete;
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CallableWrapper& operator=(const CallableWrapper&) = delete;
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Out call(In... in) const final override
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{
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if constexpr (requires { m_callable(forward<In>(in)...); }) {
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return m_callable(forward<In>(in)...);
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} else if constexpr (requires { m_callable(); }) {
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return m_callable();
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} else if constexpr (IsVoid<Out>) {
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return;
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} else {
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return {};
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}
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}
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private:
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CallableType m_callable;
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};
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OwnPtr<CallableWrapperBase> m_callable_wrapper;
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};
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}
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using AK::Function;
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