248 lines
7.0 KiB
C++
248 lines
7.0 KiB
C++
/*
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* Copyright (c) Facebook, Inc. and its affiliates.
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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// included by Future.h, do not include directly.
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namespace folly {
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template <class>
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class Promise;
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template <class T>
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class SemiFuture;
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template <typename T>
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struct isSemiFuture : std::false_type {
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using Inner = lift_unit_t<T>;
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};
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template <typename T>
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struct isSemiFuture<SemiFuture<T>> : std::true_type {
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typedef T Inner;
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};
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template <typename T>
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struct isFuture : std::false_type {
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using Inner = lift_unit_t<T>;
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};
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template <typename T>
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struct isFuture<Future<T>> : std::true_type {
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typedef T Inner;
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};
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template <typename T>
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struct isFutureOrSemiFuture : std::false_type {
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using Inner = lift_unit_t<T>;
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using Return = Inner;
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};
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template <typename T>
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struct isFutureOrSemiFuture<Try<T>> : std::false_type {
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using Inner = lift_unit_t<T>;
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using Return = Inner;
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};
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template <typename T>
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struct isFutureOrSemiFuture<Future<T>> : std::true_type {
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typedef T Inner;
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using Return = Future<Inner>;
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};
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template <typename T>
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struct isFutureOrSemiFuture<Future<Try<T>>> : std::true_type {
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typedef T Inner;
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using Return = Future<Inner>;
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};
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template <typename T>
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struct isFutureOrSemiFuture<SemiFuture<T>> : std::true_type {
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typedef T Inner;
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using Return = SemiFuture<Inner>;
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};
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template <typename T>
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struct isFutureOrSemiFuture<SemiFuture<Try<T>>> : std::true_type {
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typedef T Inner;
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using Return = SemiFuture<Inner>;
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};
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namespace futures {
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namespace detail {
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template <class>
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class Core;
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template <typename...>
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struct ArgType;
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template <typename Arg, typename... Args>
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struct ArgType<Arg, Args...> {
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typedef Arg FirstArg;
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typedef ArgType<Args...> Tail;
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};
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template <>
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struct ArgType<> {
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typedef void FirstArg;
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};
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template <bool isTry_, typename F, typename... Args>
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struct argResult {
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using Function = F;
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using ArgList = ArgType<Args...>;
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using Result = invoke_result_t<F, Args...>;
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using ArgsSize = index_constant<sizeof...(Args)>;
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static constexpr bool isTry() {
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return isTry_;
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}
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};
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template <typename T, typename F>
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struct callableResult {
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typedef typename std::conditional<
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is_invocable_v<F>,
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detail::argResult<false, F>,
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typename std::conditional<
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is_invocable_v<F, T&&>,
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detail::argResult<false, F, T&&>,
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detail::argResult<true, F, Try<T>&&>>::type>::type Arg;
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typedef isFutureOrSemiFuture<typename Arg::Result> ReturnsFuture;
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typedef Future<typename ReturnsFuture::Inner> Return;
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};
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template <typename T, typename F>
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struct executorCallableResult {
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typedef typename std::conditional<
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is_invocable_v<F, Executor::KeepAlive<>&&>,
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detail::argResult<false, F, Executor::KeepAlive<>&&>,
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typename std::conditional<
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is_invocable_v<F, Executor::KeepAlive<>&&, T&&>,
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detail::argResult<false, F, Executor::KeepAlive<>&&, T&&>,
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detail::argResult<true, F, Executor::KeepAlive<>&&, Try<T>&&>>::
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type>::type Arg;
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typedef isFutureOrSemiFuture<typename Arg::Result> ReturnsFuture;
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typedef Future<typename ReturnsFuture::Inner> Return;
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};
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template <
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typename T,
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typename F,
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typename = std::enable_if_t<is_invocable_v<F, Try<T>&&>>>
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struct tryCallableResult {
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typedef detail::argResult<true, F, Try<T>&&> Arg;
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typedef isFutureOrSemiFuture<typename Arg::Result> ReturnsFuture;
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typedef typename ReturnsFuture::Inner value_type;
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typedef Future<value_type> Return;
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};
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template <
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typename T,
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typename F,
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typename = std::enable_if_t<is_invocable_v<F, Executor*, Try<T>&&>>>
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struct tryExecutorCallableResult {
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typedef detail::argResult<true, F, Executor::KeepAlive<>&&, Try<T>&&> Arg;
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typedef isFutureOrSemiFuture<typename Arg::Result> ReturnsFuture;
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typedef typename ReturnsFuture::Inner value_type;
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typedef Future<value_type> Return;
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};
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template <typename T, typename F>
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struct valueCallableResult {
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typedef detail::argResult<false, F, T&&> Arg;
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typedef isFutureOrSemiFuture<typename Arg::Result> ReturnsFuture;
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typedef typename ReturnsFuture::Inner value_type;
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typedef typename Arg::ArgList::FirstArg FirstArg;
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typedef Future<value_type> Return;
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};
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template <typename T, typename F>
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struct valueExecutorCallableResult {
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typedef detail::argResult<false, F, Executor::KeepAlive<>&&, T&&> Arg;
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typedef isFutureOrSemiFuture<typename Arg::Result> ReturnsFuture;
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typedef typename ReturnsFuture::Inner value_type;
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typedef typename Arg::ArgList::Tail::FirstArg ValueArg;
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typedef Future<value_type> Return;
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};
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template <typename L>
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struct Extract : Extract<decltype(&L::operator())> {};
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template <typename Class, typename R, typename... Args>
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struct Extract<R (Class::*)(Args...) const> {
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typedef isFutureOrSemiFuture<R> ReturnsFuture;
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typedef Future<typename ReturnsFuture::Inner> Return;
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typedef typename ReturnsFuture::Inner RawReturn;
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typedef typename ArgType<Args...>::FirstArg FirstArg;
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};
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template <typename Class, typename R, typename... Args>
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struct Extract<R (Class::*)(Args...)> {
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typedef isFutureOrSemiFuture<R> ReturnsFuture;
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typedef Future<typename ReturnsFuture::Inner> Return;
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typedef typename ReturnsFuture::Inner RawReturn;
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typedef typename ArgType<Args...>::FirstArg FirstArg;
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};
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template <typename R, typename... Args>
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struct Extract<R (*)(Args...)> {
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typedef isFutureOrSemiFuture<R> ReturnsFuture;
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typedef Future<typename ReturnsFuture::Inner> Return;
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typedef typename ReturnsFuture::Inner RawReturn;
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typedef typename ArgType<Args...>::FirstArg FirstArg;
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};
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template <typename R, typename... Args>
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struct Extract<R (&)(Args...)> {
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typedef isFutureOrSemiFuture<R> ReturnsFuture;
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typedef Future<typename ReturnsFuture::Inner> Return;
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typedef typename ReturnsFuture::Inner RawReturn;
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typedef typename ArgType<Args...>::FirstArg FirstArg;
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};
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class DeferredExecutor;
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template <class T, class F>
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auto makeExecutorLambda(
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F&& func,
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typename std::enable_if<is_invocable_v<F>, int>::type = 0) {
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return
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[func = std::forward<F>(func)](Executor::KeepAlive<>&&, auto&&) mutable {
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return std::forward<F>(func)();
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};
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}
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template <class T, class F>
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auto makeExecutorLambda(
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F&& func,
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typename std::enable_if<!is_invocable_v<F>, int>::type = 0) {
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using R = futures::detail::callableResult<T, F&&>;
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return [func = std::forward<F>(func)](
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Executor::KeepAlive<>&&,
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typename R::Arg::ArgList::FirstArg&& param) mutable {
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return std::forward<F>(func)(std::forward<decltype(param)>(param));
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};
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}
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} // namespace detail
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} // namespace futures
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class Timekeeper;
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} // namespace folly
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