lazycell-1.2.1/CHANGELOG.md010064400017500001750000000132161340134355700133740ustar0000000000000000 ## v1.2.1 (2018-12-03) #### Features * Implement Clone for LazyCell and AtomicLazyCell ([30fe4a8f](https://github.com/indiv0/lazycell/commit/30fe4a8f568059b3c78ed149a810962a676cb2b2)) ## v1.2.0 (2018-09-19) #### Features * add `LazyCell::replace` for infallible access ([a63ffb90](https://github.com/indiv0/lazycell/commit/a63ffb9040a5e0683a9bbf9d3d5ef589f2ca8b7c)) ## v1.1.0 (2018-09-10) #### Documentation * add note regarding LazyCell::borrow_mut ([9d634d1f](https://github.com/indiv0/lazycell/commit/9d634d1fd9a21b7aa075d407bedf9fe77ba8b79f)) * describe mutability more consistently ([b8078029](https://github.com/indiv0/lazycell/commit/b80780294611e92efddcdd33a701b3049ab5c5eb), closes [#78](https://github.com/indiv0/lazycell/issues/78)) #### Improvements * add NONE constant for an empty AtomicLazyCell ([31aff0da](https://github.com/indiv0/lazycell/commit/31aff0dacf824841c5f38ef4acf0aa71ec4c36eb), closes [#87](https://github.com/indiv0/lazycell/issues/87)) * add `LazyCell::borrow_mut_with` and `LazyCell::try_borrow_mut_with` ([fdc6d268](https://github.com/indiv0/lazycell/commit/fdc6d268f0e9a6668768302f45fe2bb4aa9a7c34), closes [#79](https://github.com/indiv0/lazycell/issues/79), [#80](https://github.com/indiv0/lazycell/issues/80)) ## v1.0.0 (2018-06-06) #### Features * Add #![no_std] ([e59f6b55](https://github.com/indiv0/lazycell/commit/e59f6b5531e310d3df26b0eb40b1431937f38096)) ## 0.6.0 (2017-11-25) #### Bug Fixes * fix soundness hole in borrow_with ([d1f46bef](https://github.com/indiv0/lazycell/commit/d1f46bef9d1397570aa9c3e87e18e0d16e6d1585)) #### Features * add Default derives ([71bc5088](https://github.com/indiv0/lazycell/commit/71bc50880cd8e20002038197c9b890f5b76ad096)) * add LazyCell::try_borrow_with ([bffa4028](https://github.com/indiv0/lazycell/commit/bffa402896670b5c78a9ec050d82a58ee98de6fb)) * add LazyCell::borrow_mut method ([fd419dea](https://github.com/indiv0/lazycell/commit/fd419dea965ff1ad3853f26f37e8d107c6ca096c)) #### Breaking Changes * add `T: Send` for `AtomicLazyCell` `Sync` impl ([668bb2fa](https://github.com/indiv0/lazycell/commit/668bb2fa974fd6707c4c7edad292c76a9017d74d), closes [#67](https://github.com/indiv0/lazycell/issues/67)) #### Improvements * add `T: Send` for `AtomicLazyCell` `Sync` impl ([668bb2fa](https://github.com/indiv0/lazycell/commit/668bb2fa974fd6707c4c7edad292c76a9017d74d), closes [#67](https://github.com/indiv0/lazycell/issues/67)) ## v0.5.1 (2017-03-24) #### Documentation * fix missing backticks ([44bafaaf](https://github.com/indiv0/lazycell/commit/44bafaaf93a91641261f58ee38adadcd4af6458e)) #### Improvements * derive `Debug` impls ([9da0a5a2](https://github.com/indiv0/lazycell/commit/9da0a5a2ffac1fef03ef02851c2c89d26d67d225)) #### Features * Add get method for Copy types ([dc8f8209](https://github.com/indiv0/lazycell/commit/dc8f8209888b6eba6d18717eba6a22614629b997)) ## v0.5.0 (2016-12-08) #### Features * add borrow_with to LazyCell ([a15efa35](https://github.com/indiv0/lazycell/commit/a15efa359ea5a31a66ba57fc5b25f90c87b4b0dd)) ## (2016-08-17) #### Breaking Changes * **LazyCell:** return Err(value) on full cell ([68f3415d](https://github.com/indiv0/lazycell/commit/68f3415dd5d6a66ba047a133b7028ebe4f1c5070), breaks [#](https://github.com/indiv0/lazycell/issues/)) #### Improvements * **LazyCell:** return Err(value) on full cell ([68f3415d](https://github.com/indiv0/lazycell/commit/68f3415dd5d6a66ba047a133b7028ebe4f1c5070), breaks [#](https://github.com/indiv0/lazycell/issues/)) ## (2016-08-16) #### Features * add AtomicLazyCell which is thread-safe ([85afbd36](https://github.com/indiv0/lazycell/commit/85afbd36d8a148e14cc53654b39ddb523980124d)) #### Improvements * Use UnsafeCell instead of RefCell ([3347a8e9](https://github.com/indiv0/lazycell/commit/3347a8e97d2215a47e25c1e2fc953e8052ad8eb6)) ## (2016-04-18) #### Documentation * put types in between backticks ([607cf939](https://github.com/indiv0/lazycell/commit/607cf939b05e35001ba3070ec7a0b17b064e7be1)) ## v0.2.0 (2016-03-28) #### Features * **lazycell:** * add tests for `LazyCell` struct ([38f1313d](https://github.com/indiv0/lazycell/commit/38f1313d98542ca8c98b424edfa9ba9c3975f99e), closes [#30](https://github.com/indiv0/lazycell/issues/30)) * remove unnecessary `Default` impl ([68c16d2d](https://github.com/indiv0/lazycell/commit/68c16d2df4e9d13d5298162c06edf918246fd758)) #### Documentation * **CHANGELOG:** removed unnecessary sections ([1cc0555d](https://github.com/indiv0/lazycell/commit/1cc0555d875898a01b0832ff967aed6b40e720eb)) * **README:** add link to documentation ([c8dc33f0](https://github.com/indiv0/lazycell/commit/c8dc33f01f2c0dc187f59ee53a2b73081053012b), closes [#13](https://github.com/indiv0/lazycell/issues/13)) ## v0.1.0 (2016-03-16) #### Features * **lib.rs:** implement Default trait for LazyCell ([150a6304](https://github.com/indiv0/LazyCell/commit/150a6304a230ee1de8424e49c447ec1b2d6578ce)) ## v0.0.1 (2016-03-16) #### Bug Fixes * **Cargo.toml:** loosen restrictions on Clippy version ([84dd8f96](https://github.com/indiv0/LazyCell/commit/84dd8f960000294f9dad47d776a41b98ed812981)) #### Features * add initial implementation ([4b39764a](https://github.com/indiv0/LazyCell/commit/4b39764a575bcb701dbd8047b966f72720fd18a4)) * add initial commit ([a80407a9](https://github.com/indiv0/LazyCell/commit/a80407a907ef7c9401f120104663172f6965521a)) lazycell-1.2.1/Cargo.toml.orig010064400017500001750000000012461340134355700144520ustar0000000000000000[package] name = "lazycell" version = "1.2.1" authors = ["Alex Crichton ", "Nikita Pekin "] description = "A library providing a lazily filled Cell struct" repository = "https://github.com/indiv0/lazycell" documentation = "http://indiv0.github.io/lazycell/lazycell/" readme = "README.md" keywords = ["lazycell", "lazy", "cell", "library"] license = "MIT/Apache-2.0" include = [ "CHANGELOG.md", "Cargo.toml", "LICENSE-MIT", "LICENSE-APACHE", "README.md", "src/**/*.rs", ] [dependencies] clippy = { version = "0.0", optional = true } [features] nightly = [] nightly-testing = ["clippy", "nightly"] lazycell-1.2.1/Cargo.toml0000644000000022040000000000000107070ustar00# THIS FILE IS AUTOMATICALLY GENERATED BY CARGO # # When uploading crates to the registry Cargo will automatically # "normalize" Cargo.toml files for maximal compatibility # with all versions of Cargo and also rewrite `path` dependencies # to registry (e.g. crates.io) dependencies # # If you believe there's an error in this file please file an # issue against the rust-lang/cargo repository. If you're # editing this file be aware that the upstream Cargo.toml # will likely look very different (and much more reasonable) [package] name = "lazycell" version = "1.2.1" authors = ["Alex Crichton ", "Nikita Pekin "] include = ["CHANGELOG.md", "Cargo.toml", "LICENSE-MIT", "LICENSE-APACHE", "README.md", "src/**/*.rs"] description = "A library providing a lazily filled Cell struct" documentation = "http://indiv0.github.io/lazycell/lazycell/" readme = "README.md" keywords = ["lazycell", "lazy", "cell", "library"] license = "MIT/Apache-2.0" repository = "https://github.com/indiv0/lazycell" [dependencies.clippy] version = "0.0" optional = true [features] nightly = [] nightly-testing = ["clippy", "nightly"] lazycell-1.2.1/LICENSE-APACHE010064400017500001750000000251371316775541000135200ustar0000000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. Definitions. "License" shall mean the terms and conditions for use, reproduction, and distribution as defined by Sections 1 through 9 of this document. "Licensor" shall mean the copyright owner or entity authorized by the copyright owner that is granting the License. "Legal Entity" shall mean the union of the acting entity and all other entities that control, are controlled by, or are under common control with that entity. For the purposes of this definition, "control" means (i) the power, direct or indirect, to cause the direction or management of such entity, whether by contract or otherwise, or (ii) ownership of fifty percent (50%) or more of the outstanding shares, or (iii) beneficial ownership of such entity. "You" (or "Your") shall mean an individual or Legal Entity exercising permissions granted by this License. "Source" form shall mean the preferred form for making modifications, including but not limited to software source code, documentation source, and configuration files. "Object" form shall mean any form resulting from mechanical transformation or translation of a Source form, including but not limited to compiled object code, generated documentation, and conversions to other media types. "Work" shall mean the work of authorship, whether in Source or Object form, made available under the License, as indicated by a copyright notice that is included in or attached to the work (an example is provided in the Appendix below). "Derivative Works" shall mean any work, whether in Source or Object form, that is based on (or derived from) the Work and for which the editorial revisions, annotations, elaborations, or other modifications represent, as a whole, an original work of authorship. For the purposes of this License, Derivative Works shall not include works that remain separable from, or merely link (or bind by name) to the interfaces of, the Work and Derivative Works thereof. "Contribution" shall mean any work of authorship, including the original version of the Work and any modifications or additions to that Work or Derivative Works thereof, that is intentionally submitted to Licensor for inclusion in the Work by the copyright owner or by an individual or Legal Entity authorized to submit on behalf of the copyright owner. For the purposes of this definition, "submitted" means any form of electronic, verbal, or written communication sent to the Licensor or its representatives, including but not limited to communication on electronic mailing lists, source code control systems, and issue tracking systems that are managed by, or on behalf of, the Licensor for the purpose of discussing and improving the Work, but excluding communication that is conspicuously marked or otherwise designated in writing by the copyright owner as "Not a Contribution." "Contributor" shall mean Licensor and any individual or Legal Entity on behalf of whom a Contribution has been received by Licensor and subsequently incorporated within the Work. 2. Grant of Copyright License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable copyright license to reproduce, prepare Derivative Works of, publicly display, publicly perform, sublicense, and distribute the Work and such Derivative Works in Source or Object form. 3. Grant of Patent License. Subject to the terms and conditions of this License, each Contributor hereby grants to You a perpetual, worldwide, non-exclusive, no-charge, royalty-free, irrevocable (except as stated in this section) patent license to make, have made, use, offer to sell, sell, import, and otherwise transfer the Work, where such license applies only to those patent claims licensable by such Contributor that are necessarily infringed by their Contribution(s) alone or by combination of their Contribution(s) with the Work to which such Contribution(s) was submitted. If You institute patent litigation against any entity (including a cross-claim or counterclaim in a lawsuit) alleging that the Work or a Contribution incorporated within the Work constitutes direct or contributory patent infringement, then any patent licenses granted to You under this License for that Work shall terminate as of the date such litigation is filed. 4. Redistribution. You may reproduce and distribute copies of the Work or Derivative Works thereof in any medium, with or without modifications, and in Source or Object form, provided that You meet the following conditions: (a) You must give any other recipients of the Work or Derivative Works a copy of this License; and (b) You must cause any modified files to carry prominent notices stating that You changed the files; and (c) You must retain, in the Source form of any Derivative Works that You distribute, all copyright, patent, trademark, and attribution notices from the Source form of the Work, excluding those notices that do not pertain to any part of the Derivative Works; and (d) If the Work includes a "NOTICE" text file as part of its distribution, then any Derivative Works that You distribute must include a readable copy of the attribution notices contained within such NOTICE file, excluding those notices that do not pertain to any part of the Derivative Works, in at least one of the following places: within a NOTICE text file distributed as part of the Derivative Works; within the Source form or documentation, if provided along with the Derivative Works; or, within a display generated by the Derivative Works, if and wherever such third-party notices normally appear. The contents of the NOTICE file are for informational purposes only and do not modify the License. You may add Your own attribution notices within Derivative Works that You distribute, alongside or as an addendum to the NOTICE text from the Work, provided that such additional attribution notices cannot be construed as modifying the License. You may add Your own copyright statement to Your modifications and may provide additional or different license terms and conditions for use, reproduction, or distribution of Your modifications, or for any such Derivative Works as a whole, provided Your use, reproduction, and distribution of the Work otherwise complies with the conditions stated in this License. 5. Submission of Contributions. Unless You explicitly state otherwise, any Contribution intentionally submitted for inclusion in the Work by You to the Licensor shall be under the terms and conditions of this License, without any additional terms or conditions. Notwithstanding the above, nothing herein shall supersede or modify the terms of any separate license agreement you may have executed with Licensor regarding such Contributions. 6. Trademarks. This License does not grant permission to use the trade names, trademarks, service marks, or product names of the Licensor, except as required for reasonable and customary use in describing the origin of the Work and reproducing the content of the NOTICE file. 7. Disclaimer of Warranty. Unless required by applicable law or agreed to in writing, Licensor provides the Work (and each Contributor provides its Contributions) on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. You are solely responsible for determining the appropriateness of using or redistributing the Work and assume any risks associated with Your exercise of permissions under this License. 8. Limitation of Liability. In no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall any Contributor be liable to You for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising as a result of this License or out of the use or inability to use the Work (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if such Contributor has been advised of the possibility of such damages. 9. Accepting Warranty or Additional Liability. While redistributing the Work or Derivative Works thereof, You may choose to offer, and charge a fee for, acceptance of support, warranty, indemnity, or other liability obligations and/or rights consistent with this License. However, in accepting such obligations, You may act only on Your own behalf and on Your sole responsibility, not on behalf of any other Contributor, and only if You agree to indemnify, defend, and hold each Contributor harmless for any liability incurred by, or claims asserted against, such Contributor by reason of your accepting any such warranty or additional liability. END OF TERMS AND CONDITIONS APPENDIX: How to apply the Apache License to your work. To apply the Apache License to your work, attach the following boilerplate notice, with the fields enclosed by brackets "[]" replaced with your own identifying information. (Don't include the brackets!) The text should be enclosed in the appropriate comment syntax for the file format. We also recommend that a file or class name and description of purpose be included on the same "printed page" as the copyright notice for easier identification within third-party archives. Copyright [yyyy] [name of copyright owner] 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. lazycell-1.2.1/LICENSE-MIT010064400017500001750000000022121340134173100132010ustar0000000000000000Original work Copyright (c) 2014 The Rust Project Developers Modified work Copyright (c) 2016-2018 Nikita Pekin and lazycell contributors Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. lazycell-1.2.1/README.md010064400017500001750000000051601335050460600130360ustar0000000000000000# lazycell
Linux travis-badge
api-docs-badge crates-io license-badge coveralls-badge
Rust library providing a lazily filled Cell. # Table of Contents * [Usage](#usage) * [Contributing](#contributing) * [Credits](#credits) * [License](#license) ## Usage Add the following to your `Cargo.toml`: ```toml [dependencies] lazycell = "1.2" ``` And in your `lib.rs` or `main.rs`: ```rust extern crate lazycell; ``` See the [API docs][api-docs] for information on using the crate in your library. ## Contributing Contributions are always welcome! If you have an idea for something to add (code, documentation, tests, examples, etc.) feel free to give it a shot. Please read [CONTRIBUTING.md][contributing] before you start contributing. ## Credits The LazyCell library is based originally on work by The Rust Project Developers for the project [crates.io][crates-io-repo]. The list of contributors to this project can be found at [CONTRIBUTORS.md][contributors]. ## License LazyCell is distributed under the terms of both the MIT license and the Apache License (Version 2.0). See [LICENSE-APACHE][license-apache], and [LICENSE-MIT][license-mit] for details. [api-docs]: https://indiv0.github.io/lazycell/lazycell [contributing]: https://github.com/indiv0/lazycell/blob/master/CONTRIBUTING.md "Contribution Guide" [contributors]: https://github.com/indiv0/lazycell/blob/master/CONTRIBUTORS.md "List of Contributors" [crates-io-repo]: https://github.com/rust-lang/crates.io "rust-lang/crates.io: Source code for crates.io" [license-apache]: https://github.com/indiv0/lazycell/blob/master/LICENSE-APACHE "Apache-2.0 License" [license-mit]: https://github.com/indiv0/lazycell/blob/master/LICENSE-MIT "MIT License" lazycell-1.2.1/src/lib.rs010064400017500001750000000464441340134173100134670ustar0000000000000000// Original work Copyright (c) 2014 The Rust Project Developers // Modified work Copyright (c) 2016-2018 Nikita Pekin and the lazycell contributors // See the README.md file at the top-level directory of this distribution. // // Licensed under the Apache License, Version 2.0 or the MIT license // , at your // option. This file may not be copied, modified, or distributed // except according to those terms. #![cfg_attr(not(test), no_std)] #![deny(missing_docs)] #![cfg_attr(feature = "nightly", feature(plugin))] #![cfg_attr(feature = "clippy", plugin(clippy))] //! This crate provides a `LazyCell` struct which acts as a lazily filled //! `Cell`. //! //! With a `RefCell`, the inner contents cannot be borrowed for the lifetime of //! the entire object, but only of the borrows returned. A `LazyCell` is a //! variation on `RefCell` which allows borrows to be tied to the lifetime of //! the outer object. //! //! # Example //! //! The following example shows a quick example of the basic functionality of //! `LazyCell`. //! //! ``` //! use lazycell::LazyCell; //! //! let lazycell = LazyCell::new(); //! //! assert_eq!(lazycell.borrow(), None); //! assert!(!lazycell.filled()); //! lazycell.fill(1).ok(); //! assert!(lazycell.filled()); //! assert_eq!(lazycell.borrow(), Some(&1)); //! assert_eq!(lazycell.into_inner(), Some(1)); //! ``` //! //! `AtomicLazyCell` is a variant that uses an atomic variable to manage //! coordination in a thread-safe fashion. The limitation of an `AtomicLazyCell` //! is that after it is initialized, it can't be modified. #[cfg(not(test))] #[macro_use] extern crate core as std; use std::cell::UnsafeCell; use std::mem; use std::sync::atomic::{AtomicUsize, Ordering}; /// A lazily filled `Cell`, with mutable contents. /// /// A `LazyCell` is completely frozen once filled, **unless** you have `&mut` /// access to it, in which case `LazyCell::borrow_mut` may be used to mutate the /// contents. #[derive(Debug, Default)] pub struct LazyCell { inner: UnsafeCell>, } impl LazyCell { /// Creates a new, empty, `LazyCell`. pub fn new() -> LazyCell { LazyCell { inner: UnsafeCell::new(None) } } /// Put a value into this cell. /// /// This function will return `Err(value)` is the cell is already full. pub fn fill(&self, value: T) -> Result<(), T> { let slot = unsafe { &mut *self.inner.get() }; if slot.is_some() { return Err(value); } *slot = Some(value); Ok(()) } /// Put a value into this cell. /// /// Note that this function is infallible but requires `&mut self`. By /// requiring `&mut self` we're guaranteed that no active borrows to this /// cell can exist so we can always fill in the value. This may not always /// be usable, however, as `&mut self` may not be possible to borrow. /// /// # Return value /// /// This function returns the previous value, if any. pub fn replace(&mut self, value: T) -> Option { mem::replace(unsafe { &mut *self.inner.get() }, Some(value)) } /// Test whether this cell has been previously filled. pub fn filled(&self) -> bool { self.borrow().is_some() } /// Borrows the contents of this lazy cell for the duration of the cell /// itself. /// /// This function will return `Some` if the cell has been previously /// initialized, and `None` if it has not yet been initialized. pub fn borrow(&self) -> Option<&T> { unsafe { &*self.inner.get() }.as_ref() } /// Borrows the contents of this lazy cell mutably for the duration of the cell /// itself. /// /// This function will return `Some` if the cell has been previously /// initialized, and `None` if it has not yet been initialized. pub fn borrow_mut(&mut self) -> Option<&mut T> { unsafe { &mut *self.inner.get() }.as_mut() } /// Borrows the contents of this lazy cell for the duration of the cell /// itself. /// /// If the cell has not yet been filled, the cell is first filled using the /// function provided. /// /// # Panics /// /// Panics if the cell becomes filled as a side effect of `f`. pub fn borrow_with T>(&self, f: F) -> &T { if let Some(value) = self.borrow() { return value; } let value = f(); if self.fill(value).is_err() { panic!("borrow_with: cell was filled by closure") } self.borrow().unwrap() } /// Borrows the contents of this `LazyCell` mutably for the duration of the /// cell itself. /// /// If the cell has not yet been filled, the cell is first filled using the /// function provided. /// /// # Panics /// /// Panics if the cell becomes filled as a side effect of `f`. pub fn borrow_mut_with T>(&mut self, f: F) -> &mut T { if !self.filled() { let value = f(); if self.fill(value).is_err() { panic!("borrow_mut_with: cell was filled by closure") } } self.borrow_mut().unwrap() } /// Same as `borrow_with`, but allows the initializing function to fail. /// /// # Panics /// /// Panics if the cell becomes filled as a side effect of `f`. pub fn try_borrow_with(&self, f: F) -> Result<&T, E> where F: FnOnce() -> Result { if let Some(value) = self.borrow() { return Ok(value); } let value = f()?; if self.fill(value).is_err() { panic!("try_borrow_with: cell was filled by closure") } Ok(self.borrow().unwrap()) } /// Same as `borrow_mut_with`, but allows the initializing function to fail. /// /// # Panics /// /// Panics if the cell becomes filled as a side effect of `f`. pub fn try_borrow_mut_with(&mut self, f: F) -> Result<&mut T, E> where F: FnOnce() -> Result { if self.filled() { return Ok(self.borrow_mut().unwrap()); } let value = f()?; if self.fill(value).is_err() { panic!("try_borrow_mut_with: cell was filled by closure") } Ok(self.borrow_mut().unwrap()) } /// Consumes this `LazyCell`, returning the underlying value. pub fn into_inner(self) -> Option { // Rust 1.25 changed UnsafeCell::into_inner() from unsafe to safe // function. This unsafe can be removed when supporting Rust older than // 1.25 is not needed. #[allow(unused_unsafe)] unsafe { self.inner.into_inner() } } } impl LazyCell { /// Returns a copy of the contents of the lazy cell. /// /// This function will return `Some` if the cell has been previously initialized, /// and `None` if it has not yet been initialized. pub fn get(&self) -> Option { unsafe { *self.inner.get() } } } impl Clone for LazyCell { /// Create a clone of this `LazyCell` /// /// If self has not been initialized, returns an uninitialized `LazyCell` /// otherwise returns a `LazyCell` already initialized with a clone of the /// contents of self. fn clone(&self) -> LazyCell { LazyCell { inner: UnsafeCell::new(self.borrow().map(Clone::clone) ) } } } // Tracks the AtomicLazyCell inner state const NONE: usize = 0; const LOCK: usize = 1; const SOME: usize = 2; /// A lazily filled and thread-safe `Cell`, with frozen contents. #[derive(Debug, Default)] pub struct AtomicLazyCell { inner: UnsafeCell>, state: AtomicUsize, } impl AtomicLazyCell { /// An empty `AtomicLazyCell`. pub const NONE: Self = Self { inner: UnsafeCell::new(None), state: AtomicUsize::new(NONE), }; /// Creates a new, empty, `AtomicLazyCell`. pub fn new() -> AtomicLazyCell { Self::NONE } /// Put a value into this cell. /// /// This function will return `Err(value)` is the cell is already full. pub fn fill(&self, t: T) -> Result<(), T> { if NONE != self.state.compare_and_swap(NONE, LOCK, Ordering::Acquire) { return Err(t); } unsafe { *self.inner.get() = Some(t) }; if LOCK != self.state.compare_and_swap(LOCK, SOME, Ordering::Release) { panic!("unable to release lock"); } Ok(()) } /// Put a value into this cell. /// /// Note that this function is infallible but requires `&mut self`. By /// requiring `&mut self` we're guaranteed that no active borrows to this /// cell can exist so we can always fill in the value. This may not always /// be usable, however, as `&mut self` may not be possible to borrow. /// /// # Return value /// /// This function returns the previous value, if any. pub fn replace(&mut self, value: T) -> Option { match mem::replace(self.state.get_mut(), SOME) { NONE | SOME => {} _ => panic!("cell in inconsistent state"), } mem::replace(unsafe { &mut *self.inner.get() }, Some(value)) } /// Test whether this cell has been previously filled. pub fn filled(&self) -> bool { self.state.load(Ordering::Acquire) == SOME } /// Borrows the contents of this lazy cell for the duration of the cell /// itself. /// /// This function will return `Some` if the cell has been previously /// initialized, and `None` if it has not yet been initialized. pub fn borrow(&self) -> Option<&T> { match self.state.load(Ordering::Acquire) { SOME => unsafe { &*self.inner.get() }.as_ref(), _ => None, } } /// Consumes this `LazyCell`, returning the underlying value. pub fn into_inner(self) -> Option { // Rust 1.25 changed UnsafeCell::into_inner() from unsafe to safe // function. This unsafe can be removed when supporting Rust older than // 1.25 is not needed. #[allow(unused_unsafe)] unsafe { self.inner.into_inner() } } } impl AtomicLazyCell { /// Returns a copy of the contents of the lazy cell. /// /// This function will return `Some` if the cell has been previously initialized, /// and `None` if it has not yet been initialized. pub fn get(&self) -> Option { match self.state.load(Ordering::Acquire) { SOME => unsafe { *self.inner.get() }, _ => None, } } } impl Clone for AtomicLazyCell { /// Create a clone of this `AtomicLazyCell` /// /// If self has not been initialized, returns an uninitialized `AtomicLazyCell` /// otherwise returns an `AtomicLazyCell` already initialized with a clone of the /// contents of self. fn clone(&self) -> AtomicLazyCell { self.borrow().map_or( Self::NONE, |v| AtomicLazyCell { inner: UnsafeCell::new(Some(v.clone())), state: AtomicUsize::new(SOME), } ) } } unsafe impl Sync for AtomicLazyCell {} unsafe impl Send for AtomicLazyCell {} #[cfg(test)] mod tests { use super::{AtomicLazyCell, LazyCell}; #[test] fn test_borrow_from_empty() { let lazycell: LazyCell = LazyCell::new(); let value = lazycell.borrow(); assert_eq!(value, None); let value = lazycell.get(); assert_eq!(value, None); } #[test] fn test_fill_and_borrow() { let lazycell = LazyCell::new(); assert!(!lazycell.filled()); lazycell.fill(1).unwrap(); assert!(lazycell.filled()); let value = lazycell.borrow(); assert_eq!(value, Some(&1)); let value = lazycell.get(); assert_eq!(value, Some(1)); } #[test] fn test_borrow_mut() { let mut lazycell = LazyCell::new(); assert!(lazycell.borrow_mut().is_none()); lazycell.fill(1).unwrap(); assert_eq!(lazycell.borrow_mut(), Some(&mut 1)); *lazycell.borrow_mut().unwrap() = 2; assert_eq!(lazycell.borrow_mut(), Some(&mut 2)); // official way to reset the cell lazycell = LazyCell::new(); assert!(lazycell.borrow_mut().is_none()); } #[test] fn test_already_filled_error() { let lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); assert_eq!(lazycell.fill(1), Err(1)); } #[test] fn test_borrow_with() { let lazycell = LazyCell::new(); let value = lazycell.borrow_with(|| 1); assert_eq!(&1, value); } #[test] fn test_borrow_with_already_filled() { let lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); let value = lazycell.borrow_with(|| 1); assert_eq!(&1, value); } #[test] fn test_borrow_with_not_called_when_filled() { let lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); let value = lazycell.borrow_with(|| 2); assert_eq!(&1, value); } #[test] #[should_panic] fn test_borrow_with_sound_with_reentrancy() { // Kudos to dbaupp for discovering this issue // https://www.reddit.com/r/rust/comments/5vs9rt/lazycell_a_rust_library_providing_a_lazilyfilled/de527xm/ let lazycell: LazyCell> = LazyCell::new(); let mut reference: Option<&i32> = None; lazycell.borrow_with(|| { let _ = lazycell.fill(Box::new(1)); reference = lazycell.borrow().map(|r| &**r); Box::new(2) }); } #[test] fn test_borrow_mut_with() { let mut lazycell = LazyCell::new(); { let value = lazycell.borrow_mut_with(|| 1); assert_eq!(&mut 1, value); *value = 2; } assert_eq!(&2, lazycell.borrow().unwrap()); } #[test] fn test_borrow_mut_with_already_filled() { let mut lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); let value = lazycell.borrow_mut_with(|| 1); assert_eq!(&1, value); } #[test] fn test_borrow_mut_with_not_called_when_filled() { let mut lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); let value = lazycell.borrow_mut_with(|| 2); assert_eq!(&1, value); } #[test] fn test_try_borrow_with_ok() { let lazycell = LazyCell::new(); let result = lazycell.try_borrow_with::<(), _>(|| Ok(1)); assert_eq!(result, Ok(&1)); } #[test] fn test_try_borrow_with_err() { let lazycell = LazyCell::<()>::new(); let result = lazycell.try_borrow_with(|| Err(1)); assert_eq!(result, Err(1)); } #[test] fn test_try_borrow_with_already_filled() { let lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); let result = lazycell.try_borrow_with::<(), _>(|| unreachable!()); assert_eq!(result, Ok(&1)); } #[test] #[should_panic] fn test_try_borrow_with_sound_with_reentrancy() { let lazycell: LazyCell> = LazyCell::new(); let mut reference: Option<&i32> = None; let _ = lazycell.try_borrow_with::<(), _>(|| { let _ = lazycell.fill(Box::new(1)); reference = lazycell.borrow().map(|r| &**r); Ok(Box::new(2)) }); } #[test] fn test_try_borrow_mut_with_ok() { let mut lazycell = LazyCell::new(); { let result = lazycell.try_borrow_mut_with::<(), _>(|| Ok(1)); assert_eq!(result, Ok(&mut 1)); *result.unwrap() = 2; } assert_eq!(&mut 2, lazycell.borrow().unwrap()); } #[test] fn test_try_borrow_mut_with_err() { let mut lazycell = LazyCell::<()>::new(); let result = lazycell.try_borrow_mut_with(|| Err(1)); assert_eq!(result, Err(1)); } #[test] fn test_try_borrow_mut_with_already_filled() { let mut lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); let result = lazycell.try_borrow_mut_with::<(), _>(|| unreachable!()); assert_eq!(result, Ok(&mut 1)); } #[test] fn test_into_inner() { let lazycell = LazyCell::new(); lazycell.fill(1).unwrap(); let value = lazycell.into_inner(); assert_eq!(value, Some(1)); } #[test] fn test_atomic_borrow_from_empty() { let lazycell: AtomicLazyCell = AtomicLazyCell::new(); let value = lazycell.borrow(); assert_eq!(value, None); let value = lazycell.get(); assert_eq!(value, None); } #[test] fn test_atomic_fill_and_borrow() { let lazycell = AtomicLazyCell::new(); assert!(!lazycell.filled()); lazycell.fill(1).unwrap(); assert!(lazycell.filled()); let value = lazycell.borrow(); assert_eq!(value, Some(&1)); let value = lazycell.get(); assert_eq!(value, Some(1)); } #[test] fn test_atomic_already_filled_panic() { let lazycell = AtomicLazyCell::new(); lazycell.fill(1).unwrap(); assert_eq!(1, lazycell.fill(1).unwrap_err()); } #[test] fn test_atomic_into_inner() { let lazycell = AtomicLazyCell::new(); lazycell.fill(1).unwrap(); let value = lazycell.into_inner(); assert_eq!(value, Some(1)); } #[test] fn normal_replace() { let mut cell = LazyCell::new(); assert_eq!(cell.fill(1), Ok(())); assert_eq!(cell.replace(2), Some(1)); assert_eq!(cell.replace(3), Some(2)); assert_eq!(cell.borrow(), Some(&3)); let mut cell = LazyCell::new(); assert_eq!(cell.replace(2), None); } #[test] fn atomic_replace() { let mut cell = AtomicLazyCell::new(); assert_eq!(cell.fill(1), Ok(())); assert_eq!(cell.replace(2), Some(1)); assert_eq!(cell.replace(3), Some(2)); assert_eq!(cell.borrow(), Some(&3)); } #[test] fn clone() { let mut cell = LazyCell::new(); let clone1 = cell.clone(); assert_eq!(clone1.borrow(), None); assert_eq!(cell.fill(1), Ok(())); let mut clone2 = cell.clone(); assert_eq!(clone1.borrow(), None); assert_eq!(clone2.borrow(), Some(&1)); assert_eq!(cell.replace(2), Some(1)); assert_eq!(clone1.borrow(), None); assert_eq!(clone2.borrow(), Some(&1)); assert_eq!(clone1.fill(3), Ok(())); assert_eq!(clone2.replace(4), Some(1)); assert_eq!(clone1.borrow(), Some(&3)); assert_eq!(clone2.borrow(), Some(&4)); assert_eq!(cell.borrow(), Some(&2)); } #[test] fn clone_atomic() { let mut cell = AtomicLazyCell::new(); let clone1 = cell.clone(); assert_eq!(clone1.borrow(), None); assert_eq!(cell.fill(1), Ok(())); let mut clone2 = cell.clone(); assert_eq!(clone1.borrow(), None); assert_eq!(clone2.borrow(), Some(&1)); assert_eq!(cell.replace(2), Some(1)); assert_eq!(clone1.borrow(), None); assert_eq!(clone2.borrow(), Some(&1)); assert_eq!(clone1.fill(3), Ok(())); assert_eq!(clone2.replace(4), Some(1)); assert_eq!(clone1.borrow(), Some(&3)); assert_eq!(clone2.borrow(), Some(&4)); assert_eq!(cell.borrow(), Some(&2)); } } lazycell-1.2.1/.cargo_vcs_info.json0000644000000001120000000000000127050ustar00{ "git": { "sha1": "db9289a32df4ba3b1de8c383b68b342be4a8a1ba" } }