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util/BindMethod: simplify MakeBindFunctionWrapper()

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Max Kellermann 2021-12-02 23:25:40 +01:00 committed by Max Kellermann
parent 7e4ba3cb72
commit acab731fef
1 changed files with 21 additions and 41 deletions
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62
src/util/BindMethod.hxx
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@ -125,14 +125,16 @@ struct MethodSignatureHelper<R (T::*)(Args...) noexcept(NoExcept)> {
}; };
/** /**
* Helper class which converts a plain function signature type to a * Helper class which converts a function pointer to a wrapper
* wrapper function pointer type. * function pointer type.
*/ */
template<typename S> template<typename S>
struct MethodWrapperWithSignature; struct FunctionSignatureHelper;
template<typename R, bool NoExcept, typename... Args> template<typename R, bool NoExcept, typename... Args>
struct MethodWrapperWithSignature<R(Args...) noexcept(NoExcept)> { struct FunctionSignatureHelper<R (*)(Args...) noexcept(NoExcept)> {
typedef R plain_signature(Args...) noexcept(NoExcept);
typedef R (*function_pointer)(void *instance, typedef R (*function_pointer)(void *instance,
Args...) noexcept(NoExcept); Args...) noexcept(NoExcept);
}; };
@ -161,52 +163,27 @@ MakeBindMethodWrapper() noexcept
return BindMethodWrapperGenerator<decltype(method), method>::Invoke; return BindMethodWrapperGenerator<decltype(method), method>::Invoke;
} }
/**
* Helper class which introspects a function pointer type.
*
* @param S the function type
*/
template<typename S>
struct FunctionTraits;
template<typename R, bool NoExcept, typename... Args>
struct FunctionTraits<R(Args...) noexcept(NoExcept)> {
/**
* A function type which describes the "plain" function
* signature.
*/
typedef R function_type(Args...) noexcept(NoExcept);
/**
* A function pointer type which describes the "plain"
* function signature.
*/
typedef R (*pointer)(Args...) noexcept(NoExcept);
};
/** /**
* Generate a wrapper function. * Generate a wrapper function.
* *
* @param S the plain function signature type * @param F the function pointer type
* @param P the plain function pointer type
* @param function the function pointer * @param function the function pointer
*/ */
template<typename S, auto function> template<typename F, auto function>
struct BindFunctionWrapperGenerator; struct BindFunctionWrapperGenerator;
template<auto function, bool NoExcept, typename R, typename... Args> template<auto function, bool NoExcept, typename R, typename... Args>
struct BindFunctionWrapperGenerator<R(Args...) noexcept(NoExcept), function> { struct BindFunctionWrapperGenerator<R (*)(Args...) noexcept(NoExcept), function> {
static R Invoke(void *, Args... args) noexcept(NoExcept) { static R Invoke(void *, Args... args) noexcept(NoExcept) {
return function(std::forward<Args>(args)...); return function(std::forward<Args>(args)...);
} }
}; };
template<typename T, typename T::pointer function> template<auto function>
typename MethodWrapperWithSignature<typename T::function_type>::function_pointer typename FunctionSignatureHelper<decltype(function)>::function_pointer
MakeBindFunctionWrapper() noexcept MakeBindFunctionWrapper() noexcept
{ {
return BindFunctionWrapperGenerator<typename T::function_type, return BindFunctionWrapperGenerator<decltype(function), function>::Invoke;
function>::Invoke;
} }
} /* namespace BindMethodDetail */ } /* namespace BindMethodDetail */
@ -245,15 +222,18 @@ BindMethod(typename BindMethodDetail::MethodSignatureHelper<decltype(method)>::c
/** /**
* Construct a #BoundMethod instance for a plain function. * Construct a #BoundMethod instance for a plain function.
* *
* @param T the #FunctionTraits class
* @param function the function pointer * @param function the function pointer
*/ */
template<typename T, typename T::pointer function> template<auto function>
constexpr BoundMethod<typename T::function_type> constexpr auto
BindFunction() noexcept BindFunction() noexcept
{ {
return BoundMethod<typename T::function_type>(nullptr, using H = BindMethodDetail::FunctionSignatureHelper<decltype(function)>;
BindMethodDetail::MakeBindFunctionWrapper<T, function>()); using plain_signature = typename H::plain_signature;
return BoundMethod<plain_signature>{
nullptr,
BindMethodDetail::MakeBindFunctionWrapper<function>(),
};
} }
/** /**
@ -261,4 +241,4 @@ BindFunction() noexcept
* #BoundMethod instance. * #BoundMethod instance.
*/ */
#define BIND_FUNCTION(function) \ #define BIND_FUNCTION(function) \
BindFunction<typename BindMethodDetail::FunctionTraits<decltype(function)>, &function>() BindFunction<&function>()