├── .gitignore ├── Cargo.toml ├── LICENSE-APACHE ├── LICENSE-MIT ├── README.md └── src └── lib.rs /.gitignore: -------------------------------------------------------------------------------- 1 | /target 2 | **/*.rs.bk 3 | Cargo.lock 4 | -------------------------------------------------------------------------------- /Cargo.toml: -------------------------------------------------------------------------------- 1 | [package] 2 | name = "gen-stream" 3 | version = "0.2.4" 4 | authors = ["Artem Vorotnikov "] 5 | edition = "2018" 6 | license = "MIT OR Apache-2.0" 7 | readme = "README.md" 8 | keywords = ["async"] 9 | categories = ["asynchronous", "rust-patterns"] 10 | repository = "https://github.com/vorot93/gen-stream" 11 | documentation = "https://docs.rs/gen-stream" 12 | description = """ 13 | Generator-based streams for Rust and futures 0.3. 14 | """ 15 | 16 | [dependencies] 17 | futures-core-preview = "0.3.0-alpha.16" 18 | pin-utils = "0.1.0-alpha.4" 19 | 20 | [dev-dependencies] 21 | futures-preview = { version = "0.3.0-alpha.16", features = ["compat"] } 22 | tokio = "0.1" 23 | 24 | [badges] 25 | maintenance = { status = "actively-developed" } 26 | -------------------------------------------------------------------------------- /LICENSE-APACHE: -------------------------------------------------------------------------------- 1 | Apache License 2 | Version 2.0, January 2004 3 | http://www.apache.org/licenses/ 4 | 5 | TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 6 | 7 | 1. Definitions. 8 | 9 | "License" shall mean the terms and conditions for use, reproduction, 10 | and distribution as defined by Sections 1 through 9 of this document. 11 | 12 | "Licensor" shall mean the copyright owner or entity authorized by 13 | the copyright owner that is granting the License. 14 | 15 | "Legal Entity" shall mean the union of the acting entity and all 16 | other entities that control, are controlled by, or are under common 17 | control with that entity. For the purposes of this definition, 18 | "control" means (i) the power, direct or indirect, to cause the 19 | direction or management of such entity, whether by contract or 20 | otherwise, or (ii) ownership of fifty percent (50%) or more of the 21 | outstanding shares, or (iii) beneficial ownership of such entity. 22 | 23 | "You" (or "Your") shall mean an individual or Legal Entity 24 | exercising permissions granted by this License. 25 | 26 | "Source" form shall mean the preferred form for making modifications, 27 | including but not limited to software source code, documentation 28 | source, and configuration files. 29 | 30 | "Object" form shall mean any form resulting from mechanical 31 | transformation or translation of a Source form, including but 32 | not limited to compiled object code, generated documentation, 33 | and conversions to other media types. 34 | 35 | "Work" shall mean the work of authorship, whether in Source or 36 | Object form, made available under the License, as indicated by a 37 | copyright notice that is included in or attached to the work 38 | (an example is provided in the Appendix below). 39 | 40 | "Derivative Works" shall mean any work, whether in Source or Object 41 | form, that is based on (or derived from) the Work and for which the 42 | editorial revisions, annotations, elaborations, or other modifications 43 | represent, as a whole, an original work of authorship. For the purposes 44 | of this License, Derivative Works shall not include works that remain 45 | separable from, or merely link (or bind by name) to the interfaces of, 46 | the Work and Derivative Works thereof. 47 | 48 | "Contribution" shall mean any work of authorship, including 49 | the original version of the Work and any modifications or additions 50 | to that Work or Derivative Works thereof, that is intentionally 51 | submitted to Licensor for inclusion in the Work by the copyright owner 52 | or by an individual or Legal Entity authorized to submit on behalf of 53 | the copyright owner. For the purposes of this definition, "submitted" 54 | means any form of electronic, verbal, or written communication sent 55 | to the Licensor or its representatives, including but not limited to 56 | communication on electronic mailing lists, source code control systems, 57 | and issue tracking systems that are managed by, or on behalf of, the 58 | Licensor for the purpose of discussing and improving the Work, but 59 | excluding communication that is conspicuously marked or otherwise 60 | designated in writing by the copyright owner as "Not a Contribution." 61 | 62 | "Contributor" shall mean Licensor and any individual or Legal Entity 63 | on behalf of whom a Contribution has been received by Licensor and 64 | subsequently incorporated within the Work. 65 | 66 | 2. Grant of Copyright License. Subject to the terms and conditions of 67 | this License, each Contributor hereby grants to You a perpetual, 68 | worldwide, non-exclusive, no-charge, royalty-free, irrevocable 69 | copyright license to reproduce, prepare Derivative Works of, 70 | publicly display, publicly perform, sublicense, and distribute the 71 | Work and such Derivative Works in Source or Object form. 72 | 73 | 3. Grant of Patent License. Subject to the terms and conditions of 74 | this License, each Contributor hereby grants to You a perpetual, 75 | worldwide, non-exclusive, no-charge, royalty-free, irrevocable 76 | (except as stated in this section) patent license to make, have made, 77 | use, offer to sell, sell, import, and otherwise transfer the Work, 78 | where such license applies only to those patent claims licensable 79 | by such Contributor that are necessarily infringed by their 80 | Contribution(s) alone or by combination of their Contribution(s) 81 | with the Work to which such Contribution(s) was submitted. If You 82 | institute patent litigation against any entity (including a 83 | cross-claim or counterclaim in a lawsuit) alleging that the Work 84 | or a Contribution incorporated within the Work constitutes direct 85 | or contributory patent infringement, then any patent licenses 86 | granted to You under this License for that Work shall terminate 87 | as of the date such litigation is filed. 88 | 89 | 4. Redistribution. You may reproduce and distribute copies of the 90 | Work or Derivative Works thereof in any medium, with or without 91 | modifications, and in Source or Object form, provided that You 92 | meet the following conditions: 93 | 94 | (a) You must give any other recipients of the Work or 95 | Derivative Works a copy of this License; and 96 | 97 | (b) You must cause any modified files to carry prominent notices 98 | stating that You changed the files; and 99 | 100 | (c) You must retain, in the Source form of any Derivative Works 101 | that You distribute, all copyright, patent, trademark, and 102 | attribution notices from the Source form of the Work, 103 | excluding those notices that do not pertain to any part of 104 | the Derivative Works; and 105 | 106 | (d) If the Work includes a "NOTICE" text file as part of its 107 | distribution, then any Derivative Works that You distribute must 108 | include a readable copy of the attribution notices contained 109 | within such NOTICE file, excluding those notices that do not 110 | pertain to any part of the Derivative Works, in at least one 111 | of the following places: within a NOTICE text file distributed 112 | as part of the Derivative Works; within the Source form or 113 | documentation, if provided along with the Derivative Works; or, 114 | within a display generated by the Derivative Works, if and 115 | wherever such third-party notices normally appear. The contents 116 | of the NOTICE file are for informational purposes only and 117 | do not modify the License. You may add Your own attribution 118 | notices within Derivative Works that You distribute, alongside 119 | or as an addendum to the NOTICE text from the Work, provided 120 | that such additional attribution notices cannot be construed 121 | as modifying the License. 122 | 123 | You may add Your own copyright statement to Your modifications and 124 | may provide additional or different license terms and conditions 125 | for use, reproduction, or distribution of Your modifications, or 126 | for any such Derivative Works as a whole, provided Your use, 127 | reproduction, and distribution of the Work otherwise complies with 128 | the conditions stated in this License. 129 | 130 | 5. Submission of Contributions. Unless You explicitly state otherwise, 131 | any Contribution intentionally submitted for inclusion in the Work 132 | by You to the Licensor shall be under the terms and conditions of 133 | this License, without any additional terms or conditions. 134 | Notwithstanding the above, nothing herein shall supersede or modify 135 | the terms of any separate license agreement you may have executed 136 | with Licensor regarding such Contributions. 137 | 138 | 6. Trademarks. This License does not grant permission to use the trade 139 | names, trademarks, service marks, or product names of the Licensor, 140 | except as required for reasonable and customary use in describing the 141 | origin of the Work and reproducing the content of the NOTICE file. 142 | 143 | 7. Disclaimer of Warranty. Unless required by applicable law or 144 | agreed to in writing, Licensor provides the Work (and each 145 | Contributor provides its Contributions) on an "AS IS" BASIS, 146 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or 147 | implied, including, without limitation, any warranties or conditions 148 | of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A 149 | PARTICULAR PURPOSE. You are solely responsible for determining the 150 | appropriateness of using or redistributing the Work and assume any 151 | risks associated with Your exercise of permissions under this License. 152 | 153 | 8. Limitation of Liability. In no event and under no legal theory, 154 | whether in tort (including negligence), contract, or otherwise, 155 | unless required by applicable law (such as deliberate and grossly 156 | negligent acts) or agreed to in writing, shall any Contributor be 157 | liable to You for damages, including any direct, indirect, special, 158 | incidental, or consequential damages of any character arising as a 159 | result of this License or out of the use or inability to use the 160 | Work (including but not limited to damages for loss of goodwill, 161 | work stoppage, computer failure or malfunction, or any and all 162 | other commercial damages or losses), even if such Contributor 163 | has been advised of the possibility of such damages. 164 | 165 | 9. Accepting Warranty or Additional Liability. While redistributing 166 | the Work or Derivative Works thereof, You may choose to offer, 167 | and charge a fee for, acceptance of support, warranty, indemnity, 168 | or other liability obligations and/or rights consistent with this 169 | License. However, in accepting such obligations, You may act only 170 | on Your own behalf and on Your sole responsibility, not on behalf 171 | of any other Contributor, and only if You agree to indemnify, 172 | defend, and hold each Contributor harmless for any liability 173 | incurred by, or claims asserted against, such Contributor by reason 174 | of your accepting any such warranty or additional liability. 175 | 176 | END OF TERMS AND CONDITIONS 177 | 178 | APPENDIX: How to apply the Apache License to your work. 179 | 180 | To apply the Apache License to your work, attach the following 181 | boilerplate notice, with the fields enclosed by brackets "[]" 182 | replaced with your own identifying information. (Don't include 183 | the brackets!) The text should be enclosed in the appropriate 184 | comment syntax for the file format. We also recommend that a 185 | file or class name and description of purpose be included on the 186 | same "printed page" as the copyright notice for easier 187 | identification within third-party archives. 188 | 189 | Copyright [yyyy] [name of copyright owner] 190 | 191 | Licensed under the Apache License, Version 2.0 (the "License"); 192 | you may not use this file except in compliance with the License. 193 | You may obtain a copy of the License at 194 | 195 | http://www.apache.org/licenses/LICENSE-2.0 196 | 197 | Unless required by applicable law or agreed to in writing, software 198 | distributed under the License is distributed on an "AS IS" BASIS, 199 | WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 200 | See the License for the specific language governing permissions and 201 | limitations under the License. 202 | -------------------------------------------------------------------------------- /LICENSE-MIT: -------------------------------------------------------------------------------- 1 | Copyright (c) 2019 Artem Vorotnikov 2 | 3 | Permission is hereby granted, free of charge, to any 4 | person obtaining a copy of this software and associated 5 | documentation files (the "Software"), to deal in the 6 | Software without restriction, including without 7 | limitation the rights to use, copy, modify, merge, 8 | publish, distribute, sublicense, and/or sell copies of 9 | the Software, and to permit persons to whom the Software 10 | is furnished to do so, subject to the following 11 | conditions: 12 | 13 | The above copyright notice and this permission notice 14 | shall be included in all copies or substantial portions 15 | of the Software. 16 | 17 | THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF 18 | ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED 19 | TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A 20 | PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT 21 | SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY 22 | CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION 23 | OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR 24 | IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER 25 | DEALINGS IN THE SOFTWARE. 26 | -------------------------------------------------------------------------------- /README.md: -------------------------------------------------------------------------------- 1 | # gen-stream 2 | 3 | Generator-based streams for Rust and futures 0.3. 4 | 5 | [Documentation](https://docs.rs/gen-stream) 6 | 7 | ### What is this for? 8 | Rust ecosystem is currently moving towards asynchronous computation based on [Future](https://doc.rust-lang.org/nightly/std/future/trait.Future.html) trait and friends. One part of this is enabling us to write Futures-based code in synchronous fashion using [async/await](). 9 | 10 | This is only for `Future`, however. How do you write a complicated asynchronous iterator ([Stream](https://docs.rs/futures-preview/*/futures/stream/trait.Stream.html), that is) without rolling enum-based state-machine? [async yield](https://github.com/rust-lang/rfcs/blob/master/text/2394-async_await.md#generators-and-streams) functions are supposed to give us a hand eventually. But until such time comes... 11 | 12 | Just write your own generator and wrap it in one of GenStreams. 13 | 14 | ### How can I use this? 15 | You need Rust nightly 2019-05-09 or later. 16 | 17 | Add this to Cargo.toml: 18 | 19 | ```toml 20 | gen-stream = "0.2" 21 | ``` 22 | 23 | ### Example 24 | 25 | ```rust 26 | #![feature(async_await)] 27 | #![feature(never_type)] 28 | #![feature(generators)] 29 | #![feature(generator_trait)] 30 | #![feature(gen_future)] 31 | 32 | use { 33 | futures::{ 34 | compat::*, 35 | prelude::*, 36 | task::Poll, 37 | }, 38 | gen_stream::{gen_await, GenPerpetualStream}, 39 | std::{ops::Generator, time::{Duration, SystemTime}}, 40 | tokio::{runtime::current_thread::Runtime, timer::Interval}, 41 | }; 42 | 43 | fn current_time() -> impl Generator, Return = !> { 44 | static move || { 45 | let mut i = Interval::new_interval(Duration::from_millis(500)).compat(); 46 | 47 | loop { 48 | let _ = gen_await!(i.next()).unwrap().unwrap(); 49 | 50 | yield Poll::Ready(SystemTime::now()); 51 | } 52 | } 53 | } 54 | 55 | fn main() { 56 | let mut time_streamer = GenPerpetualStream::from(Box::pin(current_time())); 57 | 58 | let mut rt = Runtime::new().unwrap(); 59 | rt.spawn(Compat::new(async move { 60 | for _ in 0..3 { 61 | let current_time = time_streamer.next().await; 62 | println!("Current time is {:?}", current_time); 63 | } 64 | 65 | Ok(()) 66 | }.boxed())); 67 | rt.run(); 68 | } 69 | ``` 70 | 71 | License: MIT OR Apache-2.0 72 | -------------------------------------------------------------------------------- /src/lib.rs: -------------------------------------------------------------------------------- 1 | //! Generator-based streams for Rust and futures 0.3. 2 | //! 3 | //! ## What is this for? 4 | //! Rust ecosystem is currently moving towards asynchronous computation based on [Future](https://doc.rust-lang.org/nightly/std/future/trait.Future.html) trait and friends. One part of this is enabling us to write Futures-based code in synchronous fashion using [async/await](). 5 | //! 6 | //! This is only for `Future`, however. How do you write a complicated asynchronous iterator ([Stream](https://docs.rs/futures-preview/*/futures/stream/trait.Stream.html), that is) without rolling enum-based state-machine? [async yield](https://github.com/rust-lang/rfcs/blob/master/text/2394-async_await.md#generators-and-streams) functions are supposed to give us a hand eventually. But until such time comes... 7 | //! 8 | //! Just write your own generator and wrap it in one of GenStreams. 9 | //! 10 | //! ## How can I use this? 11 | //! You need Rust nightly 2019-05-09 or later. 12 | //! 13 | //! Add this to Cargo.toml: 14 | //! 15 | //! ```toml 16 | //! gen-stream = "0.2" 17 | //! ``` 18 | //! 19 | //! ## Example 20 | //! 21 | //! ```rust 22 | //! #![feature(async_await)] 23 | //! #![feature(never_type)] 24 | //! #![feature(generators)] 25 | //! #![feature(generator_trait)] 26 | //! #![feature(gen_future)] 27 | //! 28 | //! use { 29 | //! futures::{ 30 | //! compat::*, 31 | //! prelude::*, 32 | //! task::Poll, 33 | //! }, 34 | //! gen_stream::{gen_await, GenPerpetualStream}, 35 | //! std::{ops::Generator, time::{Duration, SystemTime}}, 36 | //! tokio::{runtime::current_thread::Runtime, timer::Interval}, 37 | //! }; 38 | //! 39 | //! fn current_time() -> impl Generator, Return = !> { 40 | //! static move || { 41 | //! let mut i = Interval::new_interval(Duration::from_millis(500)).compat(); 42 | //! 43 | //! loop { 44 | //! let _ = gen_await!(i.next()).unwrap().unwrap(); 45 | //! 46 | //! yield Poll::Ready(SystemTime::now()); 47 | //! } 48 | //! } 49 | //! } 50 | //! 51 | //! fn main() { 52 | //! let mut time_streamer = GenPerpetualStream::from(Box::pin(current_time())); 53 | //! 54 | //! let mut rt = Runtime::new().unwrap(); 55 | //! rt.spawn(Compat::new(async move { 56 | //! for _ in 0..3 { 57 | //! let current_time = time_streamer.next().await; 58 | //! println!("Current time is {:?}", current_time); 59 | //! } 60 | //! 61 | //! Ok(()) 62 | //! }.boxed())); 63 | //! rt.run(); 64 | //! } 65 | //! ``` 66 | 67 | #![feature(generator_trait)] 68 | #![feature(gen_future)] 69 | #![feature(never_type)] 70 | 71 | use { 72 | core::{ 73 | ops::{Generator, GeneratorState}, 74 | pin::Pin, 75 | task::{Context, Poll}, 76 | }, 77 | futures_core::*, 78 | pin_utils::unsafe_pinned, 79 | std::future::set_task_context, 80 | }; 81 | 82 | /// Like await!() but for bare generators. 83 | #[macro_export] 84 | macro_rules! gen_await { 85 | ($e:expr) => {{ 86 | let mut pinned = $e; 87 | loop { 88 | if let ::core::task::Poll::Ready(x) = std::future::poll_with_tls_context(unsafe { 89 | ::core::pin::Pin::new_unchecked(&mut pinned) 90 | }) { 91 | break x; 92 | } 93 | yield ::core::task::Poll::Pending; 94 | } 95 | }}; 96 | } 97 | 98 | /// Simple generator-based stream. 99 | pub struct GenStream { 100 | inner: G, 101 | } 102 | 103 | impl GenStream { 104 | unsafe_pinned!(inner: G); 105 | } 106 | 107 | impl From for GenStream { 108 | fn from(inner: G) -> Self { 109 | Self { inner } 110 | } 111 | } 112 | 113 | impl Stream for GenStream 114 | where 115 | G: Generator, Return = ()>, 116 | { 117 | type Item = Y; 118 | 119 | fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { 120 | set_task_context(cx, || match self.inner().resume() { 121 | GeneratorState::Yielded(v) => v.map(Some), 122 | GeneratorState::Complete(_) => Poll::Ready(None), 123 | }) 124 | } 125 | } 126 | 127 | impl Unpin for GenStream {} 128 | 129 | /// Stream based on generator that never ends. 130 | pub struct GenPerpetualStream { 131 | inner: G, 132 | } 133 | 134 | impl GenPerpetualStream { 135 | unsafe_pinned!(inner: G); 136 | } 137 | 138 | impl From for GenPerpetualStream { 139 | fn from(inner: G) -> Self { 140 | Self { inner } 141 | } 142 | } 143 | 144 | impl Stream for GenPerpetualStream 145 | where 146 | G: Generator, Return = !>, 147 | { 148 | type Item = Y; 149 | 150 | fn poll_next(self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { 151 | set_task_context(cx, || match self.inner().resume() { 152 | GeneratorState::Yielded(v) => v.map(Some), 153 | GeneratorState::Complete(_) => unreachable!(), 154 | }) 155 | } 156 | } 157 | 158 | impl Unpin for GenPerpetualStream {} 159 | 160 | /// Stream based on generator that may fail. 161 | pub struct GenTryStream { 162 | inner: G, 163 | finished: bool, 164 | } 165 | 166 | impl GenTryStream { 167 | unsafe_pinned!(inner: G); 168 | unsafe_pinned!(finished: bool); 169 | } 170 | 171 | impl From for GenTryStream { 172 | fn from(inner: G) -> Self { 173 | Self { 174 | inner, 175 | finished: false, 176 | } 177 | } 178 | } 179 | 180 | impl Stream for GenTryStream 181 | where 182 | G: Generator, Return = Result<(), E>>, 183 | { 184 | type Item = Result; 185 | 186 | fn poll_next(mut self: Pin<&mut Self>, cx: &mut Context<'_>) -> Poll> { 187 | if self.finished { 188 | return Poll::Ready(None); 189 | } 190 | 191 | set_task_context(cx, || match self.as_mut().inner().resume() { 192 | GeneratorState::Yielded(v) => v.map(Ok).map(Some), 193 | GeneratorState::Complete(res) => { 194 | self.as_mut().finished().set(true); 195 | 196 | if let Err(e) = res { 197 | Poll::Ready(Some(Err(e))) 198 | } else { 199 | Poll::Ready(None) 200 | } 201 | } 202 | }) 203 | } 204 | } 205 | 206 | impl Unpin for GenTryStream {} 207 | --------------------------------------------------------------------------------