1/*
2 * Copyright 2018-present Facebook, Inc.
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#pragma once
18
19#include <type_traits>
20
21#include <folly/Traits.h>
22
23namespace folly {
24namespace detail {
25
26struct DefaultTag {};
27
28template <typename T>
29struct DefaultMake {
30 struct Heap {
31 std::unique_ptr<T> ptr{std::make_unique<T>()};
32 /* implicit */ operator T&() {
33 return *ptr;
34 }
35 };
36
37 using is_returnable = StrictDisjunction<
38 bool_constant<__cplusplus >= 201703ULL>,
39 std::is_copy_constructible<T>,
40 std::is_move_constructible<T>>;
41 using type = std::conditional_t<is_returnable::value, T, Heap>;
42
43 type operator()() const {
44 return type();
45 }
46};
47
48template <typename...>
49struct TypeTuple {};
50
51} // namespace detail
52} // namespace folly
53