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| /* Extracted from https://github.com/facebook/folly/blob/master/folly/functional/Invoke.h */ | ||
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| /* | ||
| * Copyright 2017-present Facebook, Inc. | ||
| * | ||
| * Licensed under the Apache License, Version 2.0 (the "License"); | ||
| * you may not use this file except in compliance with the License. | ||
| * You may obtain a copy of the License at | ||
| * | ||
| * http://www.apache.org/licenses/LICENSE-2.0 | ||
| * | ||
| * Unless required by applicable law or agreed to in writing, software | ||
| * distributed under the License is distributed on an "AS IS" BASIS, | ||
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. | ||
| * See the License for the specific language governing permissions and | ||
| * limitations under the License. | ||
| */ | ||
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| #pragma once | ||
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| #include <functional> | ||
| #include <type_traits> | ||
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| #if __cpp_lib_is_invocable >= 201703 || (_MSC_VER >= 1911 && _MSVC_LANG > 201402) | ||
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| namespace backports { | ||
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| /* using override */ using std::invoke_result; | ||
| /* using override */ using std::invoke_result_t; | ||
| /* using override */ using std::is_invocable; | ||
| /* using override */ using std::is_invocable_r; | ||
| /* using override */ using std::is_invocable_r_v; | ||
| /* using override */ using std::is_invocable_v; | ||
| /* using override */ using std::is_nothrow_invocable; | ||
| /* using override */ using std::is_nothrow_invocable_r; | ||
| /* using override */ using std::is_nothrow_invocable_r_v; | ||
| /* using override */ using std::is_nothrow_invocable_v; | ||
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| } // namespace backports | ||
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| #else | ||
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| namespace backports { | ||
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| namespace invoke_detail { | ||
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| template <bool... Bs> struct Bools { | ||
| using valid_type = bool; | ||
| static constexpr std::size_t size() { | ||
| return sizeof...(Bs); | ||
| } | ||
| }; | ||
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| template <typename T> struct Negation : std::bool_constant<!T::value> {}; | ||
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| // Lighter-weight than Conjunction, but evaluates all sub-conditions eagerly. | ||
| template <class... Ts> struct StrictConjunction : std::is_same<Bools<Ts::value...>, Bools<(Ts::value || true)...>> {}; | ||
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| template <class... Ts> | ||
| struct StrictDisjunction : Negation<std::is_same<Bools<Ts::value...>, Bools<(Ts::value && false)...>>> {}; | ||
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| template <typename F, typename... Args> | ||
| using invoke_result_ = decltype(std::invoke(std::declval<F>(), std::declval<Args>()...)); | ||
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| template <typename F, typename... Args> | ||
| struct invoke_nothrow_ : std::bool_constant<noexcept(std::invoke(std::declval<F>(), std::declval<Args>()...))> {}; | ||
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| // from: http://en.cppreference.com/w/cpp/types/result_of, CC-BY-SA | ||
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| template <typename Void, typename F, typename... Args> struct invoke_result {}; | ||
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| template <typename F, typename... Args> struct invoke_result<std::void_t<invoke_result_<F, Args...>>, F, Args...> { | ||
| using type = invoke_result_<F, Args...>; | ||
| }; | ||
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| template <typename Void, typename F, typename... Args> struct is_invocable : std::false_type {}; | ||
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| template <typename F, typename... Args> | ||
| struct is_invocable<std::void_t<invoke_result_<F, Args...>>, F, Args...> : std::true_type {}; | ||
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| template <typename Void, typename R, typename F, typename... Args> struct is_invocable_r : std::false_type {}; | ||
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| template <typename R, typename F, typename... Args> | ||
| struct is_invocable_r<std::void_t<invoke_result_<F, Args...>>, R, F, Args...> | ||
| : std::is_convertible<invoke_result_<F, Args...>, R> {}; | ||
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| template <typename Void, typename F, typename... Args> struct is_nothrow_invocable : std::false_type {}; | ||
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| template <typename F, typename... Args> | ||
| struct is_nothrow_invocable<std::void_t<invoke_result_<F, Args...>>, F, Args...> : invoke_nothrow_<F, Args...> {}; | ||
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| template <typename Void, typename R, typename F, typename... Args> struct is_nothrow_invocable_r : std::false_type {}; | ||
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| template <typename R, typename F, typename... Args> | ||
| struct is_nothrow_invocable_r<std::void_t<invoke_result_<F, Args...>>, R, F, Args...> | ||
| : StrictConjunction<std::is_convertible<invoke_result_<F, Args...>, R>, invoke_nothrow_<F, Args...>> {}; | ||
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| } // namespace invoke_detail | ||
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| // mimic: std::invoke_result, C++17 | ||
| template <typename F, typename... Args> struct invoke_result : invoke_detail::invoke_result<void, F, Args...> {}; | ||
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| // mimic: std::invoke_result_t, C++17 | ||
| template <typename F, typename... Args> using invoke_result_t = typename invoke_result<F, Args...>::type; | ||
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| // mimic: std::is_invocable, C++17 | ||
| template <typename F, typename... Args> struct is_invocable : invoke_detail::is_invocable<void, F, Args...> {}; | ||
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| // mimic: std::is_invocable_r, C++17 | ||
| template <typename R, typename F, typename... Args> | ||
| struct is_invocable_r : invoke_detail::is_invocable_r<void, R, F, Args...> {}; | ||
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| // mimic: std::is_nothrow_invocable, C++17 | ||
| template <typename F, typename... Args> | ||
| struct is_nothrow_invocable : invoke_detail::is_nothrow_invocable<void, F, Args...> {}; | ||
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| // mimic: std::is_nothrow_invocable_r, C++17 | ||
| template <typename R, typename F, typename... Args> | ||
| struct is_nothrow_invocable_r : invoke_detail::is_nothrow_invocable_r<void, R, F, Args...> {}; | ||
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| template <class Fn, class... ArgTypes> inline constexpr bool is_invocable_v = is_invocable<Fn, ArgTypes...>::value; | ||
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| template <class R, class Fn, class... ArgTypes> | ||
| inline constexpr bool is_invocable_r_v = is_invocable_r<R, Fn, ArgTypes...>::value; | ||
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| template <class Fn, class... ArgTypes> | ||
| inline constexpr bool is_nothrow_invocable_v = is_nothrow_invocable<Fn, ArgTypes...>::value; | ||
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| template <class R, class Fn, class... ArgTypes> | ||
| inline constexpr bool is_nothrow_invocable_r_v = is_nothrow_invocable_r<R, Fn, ArgTypes...>::value; | ||
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| } // namespace backports | ||
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| #endif |
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