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https://github.com/LadybirdBrowser/ladybird.git
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fc20e61e72
We currently have a fair amount of code of the form:
if (is<Child>(parent)) {
auto& child = static_cast<Child&>(parent);
if (child.foo()) {
}
}
This new cast allows us to instead write code of the form:
if (auto* child = as_if<Child>(parent); child && child->foo()) {
}
N.B. The name "as_if" was chosen because we are considering renaming
verify_cast to "as".
Co-authored-by: Tim Ledbetter <tim.ledbetter@ladybird.org>
76 lines
2 KiB
C++
76 lines
2 KiB
C++
/*
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* Copyright (c) 2020-2021, Andreas Kling <andreas@ladybird.org>
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*
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* SPDX-License-Identifier: BSD-2-Clause
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*/
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#pragma once
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#include <AK/Assertions.h>
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#include <AK/Concepts.h>
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#include <AK/Forward.h>
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#include <AK/Platform.h>
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namespace AK {
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE bool is(InputType& input)
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{
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static_assert(!SameAs<OutputType, InputType>);
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if constexpr (requires { input.template fast_is<OutputType>(); }) {
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return input.template fast_is<OutputType>();
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}
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return dynamic_cast<CopyConst<InputType, OutputType>*>(&input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE bool is(InputType* input)
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{
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return input && is<OutputType>(*input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE bool is(NonnullRefPtr<InputType> const& input)
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{
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return is<OutputType>(*input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>* verify_cast(InputType* input)
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{
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static_assert(IsBaseOf<InputType, OutputType>);
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VERIFY(!input || is<OutputType>(*input));
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return static_cast<CopyConst<InputType, OutputType>*>(input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>& verify_cast(InputType& input)
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{
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static_assert(IsBaseOf<InputType, OutputType>);
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VERIFY(is<OutputType>(input));
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return static_cast<CopyConst<InputType, OutputType>&>(input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>* as_if(InputType& input)
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{
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if (!is<OutputType>(input))
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return nullptr;
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return static_cast<CopyConst<InputType, OutputType>*>(&input);
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}
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template<typename OutputType, typename InputType>
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ALWAYS_INLINE CopyConst<InputType, OutputType>* as_if(InputType* input)
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{
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if (!input)
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return nullptr;
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return as_if<OutputType>(*input);
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}
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}
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#if USING_AK_GLOBALLY
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using AK::as_if;
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using AK::is;
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using AK::verify_cast;
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#endif
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