Template
62 lines
1.7 KiB
C++
62 lines
1.7 KiB
C++
#pragma once
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#include <concepts>
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namespace core {
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template<typename T>
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concept callable = requires { &T::operator(); };
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template<typename T>
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struct function_traits
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{
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using return_type = void;
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using first_argument_type = void;
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};
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template<typename T>
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requires callable<T>
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struct function_traits<T>
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{
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using return_type = typename function_traits<decltype(&T::operator())>::return_type;
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using first_argument_type = typename function_traits<decltype(&T::operator())>::first_argument_type;
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};
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template<typename Ret, typename Arg0, typename... Args>
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struct function_traits<Ret(Arg0, Args...)>
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{
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using return_type = typename Ret;
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using first_argument_type = typename Arg0;
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};
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template<typename Ret, typename Arg0, typename... Args>
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struct function_traits<Ret (*)(Arg0, Args...)>
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{
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using return_type = typename Ret;
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using first_argument_type = typename Arg0;
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};
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template<typename Ret, typename Class, typename Arg0, typename... Args>
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struct function_traits<Ret (Class::*)(Arg0, Args...)>
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{
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using return_type = typename Ret;
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using first_argument_type = typename Arg0;
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};
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template<typename Ret, typename Class, typename Arg0, typename... Args>
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struct function_traits<Ret (Class::*)(Arg0, Args...) const>
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{
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using return_type = typename Ret;
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using first_argument_type = typename Arg0;
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};
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template<typename T>
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using return_type_t = typename function_traits<std::remove_cvref_t<T>>::return_type;
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template<typename T>
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using first_argument_type_t = typename function_traits<std::remove_cvref_t<T>>::first_argument_type;
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template<typename T, typename Arg>
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concept callable_with_argument_converted = requires(T&& callable, Arg&& arg) { callable(core::first_argument_type_t<T>{arg}); };
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}
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