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119 lines
4.0 KiB
C++
119 lines
4.0 KiB
C++
// -*- c++ -*-
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#pragma once
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#include <type_traits>
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#include_next <functional>
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namespace std
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{
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// based on http://en.cppreference.com/w/cpp/utility/functional/invoke
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namespace detail
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{
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template <typename T>
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struct is_reference_wrapper : false_type {};
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template <typename U>
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struct is_reference_wrapper<reference_wrapper<U>> : true_type {};
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template <typename T>
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constexpr bool is_reference_wrapper_v = is_reference_wrapper<T>::value;
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#define _DEF_INVOKE(check, ret) \
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template <typename T, typename Type, typename T1, typename... Args> \
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auto INVOKE(Type T::* f, T1&& t1, Args&&... args) \
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noexcept(noexcept(ret)) \
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-> enable_if_t< \
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is_member_function_pointer_v<decltype(f)> && check, \
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decltype(ret)> \
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{ return ret; }
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_DEF_INVOKE(
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(is_base_of_v<T, decay_t<T1>>),
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(std::forward<T1>(t1).*f)(std::forward<Args>(args)...))
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_DEF_INVOKE(
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(!is_base_of_v<T, decay_t<T1>> &&
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is_reference_wrapper_v<decay_t<T1>>),
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(t1.get().*f)(std::forward<Args>(args)...))
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_DEF_INVOKE(
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(!is_base_of_v<T, decay_t<T1>> &&
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!is_reference_wrapper_v<decay_t<T1>>),
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((*std::forward<T1>(t1)).*f)(std::forward<Args>(args)...))
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#undef _DEF_INVOKE
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#define _DEF_INVOKE(check, ret) \
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template <typename T, typename Type, typename T1> \
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auto INVOKE(Type T::* f, T1&& t1) \
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noexcept(noexcept(ret)) \
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-> enable_if_t< \
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is_member_object_pointer_v<decltype(f)> && check, \
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decltype(ret)> \
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{ return ret; }
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_DEF_INVOKE(
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(is_base_of_v<T, decay_t<T1>>),
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std::forward<T1>(t1).*f)
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_DEF_INVOKE(
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(!is_base_of_v<T, decay_t<T1>> &&
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is_reference_wrapper_v<decay_t<T1>>),
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t1.get().*f)
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_DEF_INVOKE(
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(!is_base_of_v<T, decay_t<T1>> &&
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!is_reference_wrapper_v<decay_t<T1>>),
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(*std::forward<T1>(t1)).*f)
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#undef _DEF_INVOKE
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template <class F, class... Args>
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auto INVOKE(F&& f, Args&&... args)
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noexcept(noexcept(std::forward<F>(f)(std::forward<Args>(args)...)))
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-> enable_if_t<
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!is_member_function_pointer_v<F>,
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decltype(std::forward<F>(f)(std::forward<Args>(args)...))>
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{
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return std::forward<F>(f)(std::forward<Args>(args)...);
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}
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template <typename AlwaysVoid, typename F, typename... Args>
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struct invoke_result
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{
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decltype(void(INVOKE(declval<F>(), declval<Args>()...)))* x;
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};
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template <typename F, typename... Args>
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struct invoke_result<
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decltype(void(INVOKE(declval<F>(), declval<Args>()...))),
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F, Args...>
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{
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using type = decltype(INVOKE(declval<F>(), declval<Args>()...));
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};
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template <bool AlwaysTrue, typename F, typename... Args>
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struct is_nothrow_invocable : false_type {};
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template <typename F, typename... Args>
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struct is_nothrow_invocable<
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noexcept(INVOKE(declval<F>(), declval<Args>()...)),
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F, Args...> : true_type {};
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}
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template <typename F, typename... ArgTypes>
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struct invoke_result : detail::invoke_result<void, F, ArgTypes...> {};
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template <typename F, typename... ArgTypes>
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using invoke_result_t = typename invoke_result<F, ArgTypes...>::type;
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template <typename F, typename... ArgTypes>
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struct is_nothrow_invocable
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: detail::is_nothrow_invocable<true, F, ArgTypes...> {};
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template <typename F, typename... ArgTypes>
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inline constexpr bool is_nothrow_invocable_v =
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is_nothrow_invocable<F, ArgTypes...>::value;
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template <typename F, typename... Args>
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invoke_result_t<F, Args...> invoke(F&& f, Args&&... args)
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noexcept(is_nothrow_invocable_v<F, Args...>)
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{
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return detail::INVOKE(std::forward<F>(f), std::forward<Args>(args)...);
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}
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}
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