mirror of
https://github.com/ecency/ecency-mobile.git
synced 2024-12-21 04:11:50 +03:00
125 lines
3.9 KiB
C++
125 lines
3.9 KiB
C++
/*
|
|
* Copyright 2016 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.
|
|
*/
|
|
|
|
/*
|
|
* Defines a function folly::applyTuple, which takes a function and a
|
|
* std::tuple of arguments and calls the function with those
|
|
* arguments.
|
|
*
|
|
* Example:
|
|
*
|
|
* int x = folly::applyTuple(std::plus<int>(), std::make_tuple(12, 12));
|
|
* ASSERT(x == 24);
|
|
*/
|
|
|
|
#pragma once
|
|
|
|
#include <functional>
|
|
#include <tuple>
|
|
#include <utility>
|
|
|
|
namespace folly {
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
namespace detail {
|
|
namespace apply_tuple {
|
|
|
|
template <std::size_t...>
|
|
struct IndexSequence {};
|
|
|
|
template <std::size_t N, std::size_t... Is>
|
|
struct MakeIndexSequence : MakeIndexSequence<N - 1, N - 1, Is...> {};
|
|
|
|
template <std::size_t... Is>
|
|
struct MakeIndexSequence<0, Is...> : IndexSequence<Is...> {};
|
|
|
|
inline constexpr std::size_t sum() {
|
|
return 0;
|
|
}
|
|
template <typename... Args>
|
|
inline constexpr std::size_t sum(std::size_t v1, Args... vs) {
|
|
return v1 + sum(vs...);
|
|
}
|
|
|
|
template <typename... Tuples>
|
|
struct TupleSizeSum {
|
|
static constexpr auto value = sum(std::tuple_size<Tuples>::value...);
|
|
};
|
|
|
|
template <typename... Tuples>
|
|
using MakeIndexSequenceFromTuple = MakeIndexSequence<
|
|
TupleSizeSum<typename std::decay<Tuples>::type...>::value>;
|
|
|
|
// This is to allow using this with pointers to member functions,
|
|
// where the first argument in the tuple will be the this pointer.
|
|
template <class F>
|
|
inline constexpr F&& makeCallable(F&& f) {
|
|
return std::forward<F>(f);
|
|
}
|
|
template <class M, class C>
|
|
inline constexpr auto makeCallable(M(C::*d)) -> decltype(std::mem_fn(d)) {
|
|
return std::mem_fn(d);
|
|
}
|
|
|
|
template <class F, class Tuple, std::size_t... Indexes>
|
|
inline constexpr auto call(F&& f, Tuple&& t, IndexSequence<Indexes...>)
|
|
-> decltype(
|
|
std::forward<F>(f)(std::get<Indexes>(std::forward<Tuple>(t))...)) {
|
|
return std::forward<F>(f)(std::get<Indexes>(std::forward<Tuple>(t))...);
|
|
}
|
|
|
|
template <class Tuple, std::size_t... Indexes>
|
|
inline constexpr auto forwardTuple(Tuple&& t, IndexSequence<Indexes...>)
|
|
-> decltype(
|
|
std::forward_as_tuple(std::get<Indexes>(std::forward<Tuple>(t))...)) {
|
|
return std::forward_as_tuple(std::get<Indexes>(std::forward<Tuple>(t))...);
|
|
}
|
|
|
|
} // namespace apply_tuple
|
|
} // namespace detail
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
|
|
/**
|
|
* Invoke a callable object with a set of arguments passed as a tuple, or a
|
|
* series of tuples
|
|
*
|
|
* Example: the following lines are equivalent
|
|
* func(1, 2, 3, "foo");
|
|
* applyTuple(func, std::make_tuple(1, 2, 3, "foo"));
|
|
* applyTuple(func, std::make_tuple(1, 2), std::make_tuple(3, "foo"));
|
|
*/
|
|
|
|
template <class F, class... Tuples>
|
|
inline constexpr auto applyTuple(F&& f, Tuples&&... t)
|
|
-> decltype(detail::apply_tuple::call(
|
|
detail::apply_tuple::makeCallable(std::forward<F>(f)),
|
|
std::tuple_cat(detail::apply_tuple::forwardTuple(
|
|
std::forward<Tuples>(t),
|
|
detail::apply_tuple::MakeIndexSequenceFromTuple<Tuples>{})...),
|
|
detail::apply_tuple::MakeIndexSequenceFromTuple<Tuples...>{})) {
|
|
return detail::apply_tuple::call(
|
|
detail::apply_tuple::makeCallable(std::forward<F>(f)),
|
|
std::tuple_cat(detail::apply_tuple::forwardTuple(
|
|
std::forward<Tuples>(t),
|
|
detail::apply_tuple::MakeIndexSequenceFromTuple<Tuples>{})...),
|
|
detail::apply_tuple::MakeIndexSequenceFromTuple<Tuples...>{});
|
|
}
|
|
|
|
//////////////////////////////////////////////////////////////////////
|
|
}
|