| Line |
Branch |
Exec |
Source |
| 1 |
|
|
/***************************************************************************** |
| 2 |
|
|
* vim:tw=78 |
| 3 |
|
|
* |
| 4 |
|
|
* Copyright (C) 2022 Bjarne von Horn (vh at igh dot de). |
| 5 |
|
|
* |
| 6 |
|
|
* This file is part of the PdCom library. |
| 7 |
|
|
* |
| 8 |
|
|
* The PdCom library is free software: you can redistribute it and/or modify |
| 9 |
|
|
* it under the terms of the GNU Lesser General Public License as published by |
| 10 |
|
|
* the Free Software Foundation, either version 3 of the License, or (at your |
| 11 |
|
|
* option) any later version. |
| 12 |
|
|
* |
| 13 |
|
|
* The PdCom library is distributed in the hope that it will be useful, but |
| 14 |
|
|
* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY |
| 15 |
|
|
* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public |
| 16 |
|
|
* License for more details. |
| 17 |
|
|
* |
| 18 |
|
|
* You should have received a copy of the GNU Lesser General Public License |
| 19 |
|
|
* along with the PdCom library. If not, see <http://www.gnu.org/licenses/>. |
| 20 |
|
|
* |
| 21 |
|
|
*****************************************************************************/ |
| 22 |
|
|
|
| 23 |
|
|
#ifndef PDCOM5_FUTURE_H |
| 24 |
|
|
#define PDCOM5_FUTURE_H |
| 25 |
|
|
|
| 26 |
|
|
#include <functional> |
| 27 |
|
|
#include <memory> |
| 28 |
|
|
#include <pdcom5_export.h> |
| 29 |
|
|
|
| 30 |
|
|
namespace PdCom { |
| 31 |
|
|
namespace impl { |
| 32 |
|
|
template <class Exception, class... Result> |
| 33 |
|
|
struct Promise; |
| 34 |
|
|
} |
| 35 |
|
|
|
| 36 |
|
|
/** Callback management handle. |
| 37 |
|
|
* |
| 38 |
|
|
* This class can save up to two callbacks for an asynchronous operation. |
| 39 |
|
|
* When the result of the asynchronous operation arrives, |
| 40 |
|
|
* the callback set by then() is called. |
| 41 |
|
|
* On error, handle_exception() is invoked. |
| 42 |
|
|
* |
| 43 |
|
|
* Please note that this Future does not support fire-and-forget. |
| 44 |
|
|
* The Future should be kept until one of the callback was called. |
| 45 |
|
|
* If you're not interested in the result anymore, you can delete the future. |
| 46 |
|
|
* In this case, no callbacks are run. |
| 47 |
|
|
*/ |
| 48 |
|
|
template <class Exception, class... Result> |
| 49 |
|
16 |
class PDCOM5_PUBLIC Future |
| 50 |
|
|
{ |
| 51 |
|
|
public: |
| 52 |
|
|
using ResolveFn = std::function<void(Result...)>; |
| 53 |
|
|
using RejectFn = std::function<void(Exception)>; |
| 54 |
|
|
|
| 55 |
|
|
/// Default Constructor. |
| 56 |
|
43 |
Future() = default; |
| 57 |
|
8 |
Future(std::shared_ptr<impl::Promise<Exception, Result...>> impl) noexcept : |
| 58 |
|
8 |
impl_(std::move(impl)) |
| 59 |
|
8 |
{} |
| 60 |
|
16 |
Future(Future &&) = default; |
| 61 |
|
|
Future(const Future &) = delete; |
| 62 |
|
|
Future &operator=(Future &&) = default; |
| 63 |
|
|
Future &operator=(const Future &) = delete; |
| 64 |
|
|
|
| 65 |
|
|
/** Set continuation callback. |
| 66 |
|
|
* |
| 67 |
|
|
* \param resolve The callback to be invoked with the result. |
| 68 |
|
|
* \return const Reference to \c this. |
| 69 |
|
|
*/ |
| 70 |
|
|
const Future &then(ResolveFn resolve) const &; |
| 71 |
|
|
/** Set continuation callback. |
| 72 |
|
|
* |
| 73 |
|
|
* \param resolve The callback to be invoked with the result. |
| 74 |
|
|
* \return a new Future. |
| 75 |
|
|
*/ |
| 76 |
|
|
Future then(ResolveFn resolve) &&; |
| 77 |
|
|
/** Set error handling callback |
| 78 |
|
|
* |
| 79 |
|
|
* \param reject The callback to be invoked on error. |
| 80 |
|
|
* \return const Reference to \c this. |
| 81 |
|
|
*/ |
| 82 |
|
|
const Future &handle_exception(RejectFn reject) const &; |
| 83 |
|
|
/** Set error handling callback |
| 84 |
|
|
* |
| 85 |
|
|
* \param reject The callback to be invoked on error. |
| 86 |
|
|
* \return a new Future. |
| 87 |
|
|
*/ |
| 88 |
|
|
Future handle_exception(RejectFn reject) &&; |
| 89 |
|
|
|
| 90 |
|
|
/** |
| 91 |
|
|
* \return true if the Future was default-constructed. |
| 92 |
|
|
*/ |
| 93 |
|
✗ |
bool empty() const noexcept { return !impl_.operator bool(); } |
| 94 |
|
|
|
| 95 |
|
|
/// Hash support, e.g. for \c std::unordered_set |
| 96 |
|
|
struct Hash |
| 97 |
|
|
{ |
| 98 |
|
✗ |
std::size_t operator()(Future const &future) const |
| 99 |
|
|
{ |
| 100 |
|
|
return std::hash< |
| 101 |
|
✗ |
std::shared_ptr<impl::Promise<Exception, Result...>>>()( |
| 102 |
|
✗ |
future.impl_); |
| 103 |
|
|
} |
| 104 |
|
|
}; |
| 105 |
|
|
|
| 106 |
|
|
/// Less compare support, e.g. for \c std::set |
| 107 |
|
|
struct Less |
| 108 |
|
|
{ |
| 109 |
|
✗ |
bool operator()(const Future &lhs, const Future &rhs) const noexcept |
| 110 |
|
|
{ |
| 111 |
|
|
return std::owner_less< |
| 112 |
|
✗ |
std::shared_ptr<impl::Promise<Exception, Result...>>>()( |
| 113 |
|
✗ |
lhs.impl_, rhs.impl_); |
| 114 |
|
|
} |
| 115 |
|
|
}; |
| 116 |
|
|
|
| 117 |
|
|
/// Equal comparsion. |
| 118 |
|
✗ |
bool operator==(const Future &other) const noexcept |
| 119 |
|
|
{ |
| 120 |
|
✗ |
return other.impl_ == impl_; |
| 121 |
|
|
} |
| 122 |
|
|
|
| 123 |
|
|
private: |
| 124 |
|
|
std::shared_ptr<impl::Promise<Exception, Result...>> impl_; |
| 125 |
|
|
}; |
| 126 |
|
|
} // namespace PdCom |
| 127 |
|
|
|
| 128 |
|
|
namespace std { |
| 129 |
|
|
template <class Exception, class... Result> |
| 130 |
|
|
struct hash<PdCom::Future<Exception, Result...>> : |
| 131 |
|
|
PdCom::Future<Exception, Result...>::Hash |
| 132 |
|
|
{}; |
| 133 |
|
|
|
| 134 |
|
|
template <class Exception, class... Result> |
| 135 |
|
|
struct less<PdCom::Future<Exception, Result...>> : |
| 136 |
|
|
PdCom::Future<Exception, Result...>::Less |
| 137 |
|
|
{}; |
| 138 |
|
|
|
| 139 |
|
|
} // namespace std |
| 140 |
|
|
|
| 141 |
|
|
|
| 142 |
|
|
#endif // PDCOM5_FUTURE_H |
| 143 |
|
|
|