ceph/src/seastar/include/seastar/core/apply.hh

   1 /*
   2  * This file is open source software, licensed to you under the terms
   3  * of the Apache License, Version 2.0 (the "License").  See the NOTICE file
   4  * distributed with this work for additional information regarding copyright
   5  * ownership.  You may not use this file except in compliance with the License.
   6  *
   7  * You may obtain a copy of the License at
   8  *
   9  *   http://www.apache.org/licenses/LICENSE-2.0
  10  *
  11  * Unless required by applicable law or agreed to in writing,
  12  * software distributed under the License is distributed on an
  13  * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
  14  * KIND, either express or implied.  See the License for the
  15  * specific language governing permissions and limitations
  16  * under the License.
  17  */
  18 /*
  19  * Copyright (C) 2014 Cloudius Systems, Ltd.
  20  */
  21
  22 #pragma once
  23
  24 #include <tuple>
  25 #include <utility>
  26 #include <cstddef>
  27
  28 namespace seastar {
  29
  30 template <typename Func, typename Args, typename IndexList>
  31 struct apply_helper;
  32
  33 template <typename Func, typename Tuple, size_t... I>
  34 struct apply_helper<Func, Tuple, std::index_sequence<I...>> {
  35     static auto apply(Func&& func, Tuple args) {
  36         return func(std::get<I>(std::forward<Tuple>(args))...);
  37     }
  38 };
  39
  40 template <typename Func, typename... T>
  41 [[deprecated("use std::apply() instead")]]
  42 inline
  43 auto apply(Func&& func, std::tuple<T...>&& args) {
  44     using helper = apply_helper<Func, std::tuple<T...>&&, std::index_sequence_for<T...>>;
  45     return helper::apply(std::forward<Func>(func), std::move(args));
  46 }
  47
  48 template <typename Func, typename... T>
  49 [[deprecated("use std::apply() instead")]]
  50 inline
  51 auto apply(Func&& func, std::tuple<T...>& args) {
  52     using helper = apply_helper<Func, std::tuple<T...>&, std::index_sequence_for<T...>>;
  53     return helper::apply(std::forward<Func>(func), args);
  54 }
  55
  56 template <typename Func, typename... T>
  57 [[deprecated("use std::apply() instead")]]
  58 inline
  59 auto apply(Func&& func, const std::tuple<T...>& args) {
  60     using helper = apply_helper<Func, const std::tuple<T...>&, std::index_sequence_for<T...>>;
  61     return helper::apply(std::forward<Func>(func), args);
  62 }
  63
  64 }