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Diffstat (limited to 'vendor/lazycell')
| -rw-r--r-- | vendor/lazycell/.cargo-checksum.json | 1 | ||||
| -rw-r--r-- | vendor/lazycell/CHANGELOG.md | 197 | ||||
| -rw-r--r-- | vendor/lazycell/Cargo.toml | 34 | ||||
| -rw-r--r-- | vendor/lazycell/LICENSE-APACHE | 201 | ||||
| -rw-r--r-- | vendor/lazycell/LICENSE-MIT | 26 | ||||
| -rw-r--r-- | vendor/lazycell/README.md | 73 | ||||
| -rw-r--r-- | vendor/lazycell/src/lib.rs | 680 | ||||
| -rw-r--r-- | vendor/lazycell/src/serde_impl.rs | 86 |
8 files changed, 1298 insertions, 0 deletions
diff --git a/vendor/lazycell/.cargo-checksum.json b/vendor/lazycell/.cargo-checksum.json new file mode 100644 index 000000000..a5316aaaf --- /dev/null +++ b/vendor/lazycell/.cargo-checksum.json @@ -0,0 +1 @@ +{"files":{"CHANGELOG.md":"54036052985525a153f9e6c9dda6a143b7494a477908fb28f5705f92dd387059","Cargo.toml":"79f5da117603f75361b9a7309f102a9ab70b66d5c1c269a30f66fdea58ccc657","LICENSE-APACHE":"a60eea817514531668d7e00765731449fe14d059d3249e0bc93b36de45f759f2","LICENSE-MIT":"03f6ccb4e6040abccf12b31551bbbd1800a5069a17950bbd6db850d85744800f","README.md":"26e4440387d4fc898f377eb5394f3432f8625ed8aa46e02ffb61aac8b2032967","src/lib.rs":"3fcef569bd4feb760925e34aef0e66739a0827cbc1b26ae033f57e322c3a2515","src/serde_impl.rs":"4903fb722748e91bdc4b481c7f3309e79e962f75c9717e7e13edcccd0242a52d"},"package":"830d08ce1d1d941e6b30645f1a0eb5643013d835ce3779a5fc208261dbe10f55"}
\ No newline at end of file diff --git a/vendor/lazycell/CHANGELOG.md b/vendor/lazycell/CHANGELOG.md new file mode 100644 index 000000000..1ac4a6e82 --- /dev/null +++ b/vendor/lazycell/CHANGELOG.md @@ -0,0 +1,197 @@ +<a name="v1.3.0"></a> +## v1.3.0 (2020-08-12) + + +#### Bug Fixes + +* Add custom `impl Default` to support non-Default-able `<T>` types ([b49f4eab](https://github.com/indiv0/lazycell/commit/b49f4eabec49c0a5146ef01017c2506a3c357180)) +* **lazycell:** Fix unsound aliasing in `LazyCell::fill` ([e789ac1a](https://github.com/indiv0/lazycell/commit/e789ac1a99010ad79c2d09c761fec6d67053647d), closes [#98](https://github.com/indiv0/lazycell/issues/98)) + +#### Features + +* Implement serde support ([e728a0b6](https://github.com/indiv0/lazycell/commit/e728a0b680e607b793a81b5af7bf7f1d2c0eb5e5)) + +#### Documentation + +* fix typo ([5f5ba9d5](https://github.com/indiv0/lazycell/commit/5f5ba9d5ac3364f8376c0c872c2e5094974385ba)) + + + +<a name="v1.2.1"></a> +## v1.2.1 (2018-12-03) + + +#### Features + +* Implement Clone for LazyCell and AtomicLazyCell ([30fe4a8f](https://github.com/indiv0/lazycell/commit/30fe4a8f568059b3c78ed149a810962a676cb2b2)) + + + +<a name="v1.2.0"></a> +## v1.2.0 (2018-09-19) + + +#### Features + +* add `LazyCell::replace` for infallible access ([a63ffb90](https://github.com/indiv0/lazycell/commit/a63ffb9040a5e0683a9bbf9d3d5ef589f2ca8b7c)) + + + +<a name="v1.1.0"></a> +## 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)) + + + +<a name="v1.0.0"></a> +## v1.0.0 (2018-06-06) + + +#### Features + +* Add #![no_std] ([e59f6b55](https://github.com/indiv0/lazycell/commit/e59f6b5531e310d3df26b0eb40b1431937f38096)) + + + +<a name="0.6.0"></a> +## 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)) + + + +<a name="v0.5.1"></a> +## 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)) + + + +<a name="v0.5.0"></a> +## v0.5.0 (2016-12-08) + + +#### Features + +* add borrow_with to LazyCell ([a15efa35](https://github.com/indiv0/lazycell/commit/a15efa359ea5a31a66ba57fc5b25f90c87b4b0dd)) + + + +<a name="v0.4.0"></a> +## (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/)) + + + +<a name="v0.3.0"></a> +## (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)) + + + +<a name="v0.2.1"></a> +## (2016-04-18) + + +#### Documentation + +* put types in between backticks ([607cf939](https://github.com/indiv0/lazycell/commit/607cf939b05e35001ba3070ec7a0b17b064e7be1)) + + + +<a name="v0.2.0"></a> +## 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)) + + + +<a name="v0.1.0"></a> +## v0.1.0 (2016-03-16) + + +#### Features + +* **lib.rs:** implement Default trait for LazyCell ([150a6304](https://github.com/indiv0/LazyCell/commit/150a6304a230ee1de8424e49c447ec1b2d6578ce)) + + + +<a name="v0.0.1"></a> +## 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)) + + + diff --git a/vendor/lazycell/Cargo.toml b/vendor/lazycell/Cargo.toml new file mode 100644 index 000000000..fce4dd511 --- /dev/null +++ b/vendor/lazycell/Cargo.toml @@ -0,0 +1,34 @@ +# 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. 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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. diff --git a/vendor/lazycell/LICENSE-MIT b/vendor/lazycell/LICENSE-MIT new file mode 100644 index 000000000..b4cbb4b7e --- /dev/null +++ b/vendor/lazycell/LICENSE-MIT @@ -0,0 +1,26 @@ +Original 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. diff --git a/vendor/lazycell/README.md b/vendor/lazycell/README.md new file mode 100644 index 000000000..555fe397d --- /dev/null +++ b/vendor/lazycell/README.md @@ -0,0 +1,73 @@ +# lazycell + +<table> + <tr> + <td><strong>Linux</strong></td> + <td><a href="https://travis-ci.org/indiv0/lazycell" title="Travis Build Status"><img src="https://travis-ci.org/indiv0/lazycell.svg?branch=master" alt="travis-badge"></img></a></td> + </tr> + <tr> + <td colspan="2"> + <a href="https://crates.io/crates/lazycell" title="Crates.io downloads"><img src="https://img.shields.io/crates/d/lazycell.svg" alt="cargo-downloads-badge"></img></a> + <a href="https://indiv0.github.io/lazycell/lazycell" title="API Docs"><img src="https://img.shields.io/badge/API-docs-blue.svg" alt="api-docs-badge"></img></a> + <a href="https://crates.io/crates/lazycell" title="Crates.io"><img src="https://img.shields.io/crates/v/lazycell.svg" alt="crates-io"></img></a> + <a href="#license" title="License: MIT/Apache-2.0"><img src="https://img.shields.io/crates/l/lazycell.svg" alt="license-badge"></img></a> + <a href="https://coveralls.io/github/indiv0/lazycell?branch=master" title="Coverage Status"><img src="https://coveralls.io/repos/github/indiv0/lazycell/badge.svg?branch=master" alt="coveralls-badge"></img></a> + </td> + </tr> +</table> + +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 = "1.3" +``` + +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" diff --git a/vendor/lazycell/src/lib.rs b/vendor/lazycell/src/lib.rs new file mode 100644 index 000000000..53bee073b --- /dev/null +++ b/vendor/lazycell/src/lib.rs @@ -0,0 +1,680 @@ +// Original work Copyright (c) 2014 The Rust Project Developers +// Modified work Copyright (c) 2016-2020 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 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, 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; +#[cfg(feature = "serde")] +extern crate serde; + +#[cfg(feature = "serde")] +mod serde_impl; + +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)] +pub struct LazyCell<T> { + inner: UnsafeCell<Option<T>>, +} + +impl<T> LazyCell<T> { + /// Creates a new, empty, `LazyCell`. + pub fn new() -> LazyCell<T> { + LazyCell { inner: UnsafeCell::new(None) } + } + + /// Put a value into this cell. + /// + /// This function will return `Err(value)` if the cell is already full. + pub fn fill(&self, value: T) -> Result<(), T> { + let slot = unsafe { &*self.inner.get() }; + if slot.is_some() { + return Err(value); + } + let slot = unsafe { &mut *self.inner.get() }; + *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<T> { + 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<F: FnOnce() -> 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<F: FnOnce() -> 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<E, F>(&self, f: F) -> Result<&T, E> + where F: FnOnce() -> Result<T, E> + { + 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<E, F>(&mut self, f: F) -> Result<&mut T, E> + where F: FnOnce() -> Result<T, E> + { + 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<T> { + // 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<T: Copy> LazyCell<T> { + /// 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<T> { + unsafe { *self.inner.get() } + } +} + +impl<T> Default for LazyCell<T> { + fn default() -> Self { + Self::new() + } +} + +impl <T: Clone> Clone for LazyCell<T> { + /// 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<T> { + 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)] +pub struct AtomicLazyCell<T> { + inner: UnsafeCell<Option<T>>, + state: AtomicUsize, +} + +impl<T> AtomicLazyCell<T> { + /// 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<T> { + Self::NONE + } + + /// Put a value into this cell. + /// + /// This function will return `Err(value)` if 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<T> { + 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<T> { + // 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<T: Copy> AtomicLazyCell<T> { + /// 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<T> { + match self.state.load(Ordering::Acquire) { + SOME => unsafe { *self.inner.get() }, + _ => None, + } + } +} + +impl<T> Default for AtomicLazyCell<T> { + fn default() -> Self { + Self::new() + } +} + +impl<T: Clone> Clone for AtomicLazyCell<T> { + /// 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<T> { + self.borrow().map_or( + Self::NONE, + |v| AtomicLazyCell { + inner: UnsafeCell::new(Some(v.clone())), + state: AtomicUsize::new(SOME), + } + ) + } +} + +unsafe impl<T: Sync + Send> Sync for AtomicLazyCell<T> {} + +unsafe impl<T: Send> Send for AtomicLazyCell<T> {} + +#[cfg(test)] +mod tests { + use super::{AtomicLazyCell, LazyCell}; + + #[test] + fn test_borrow_from_empty() { + let lazycell: LazyCell<usize> = 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<Box<i32>> = 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<Box<i32>> = 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<usize> = 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)); + } + + #[test] + fn default() { + #[derive(Default)] + struct Defaultable; + struct NonDefaultable; + + let _: LazyCell<Defaultable> = LazyCell::default(); + let _: LazyCell<NonDefaultable> = LazyCell::default(); + + let _: AtomicLazyCell<Defaultable> = AtomicLazyCell::default(); + let _: AtomicLazyCell<NonDefaultable> = AtomicLazyCell::default(); + } +} diff --git a/vendor/lazycell/src/serde_impl.rs b/vendor/lazycell/src/serde_impl.rs new file mode 100644 index 000000000..8f08f7b03 --- /dev/null +++ b/vendor/lazycell/src/serde_impl.rs @@ -0,0 +1,86 @@ +// Copyright (c) 2020 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 <LICENSE-APACHE or +// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license +// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your +// option. This file may not be copied, modified, or distributed +// except according to those terms.use serde::ser::{Serialize, Serializer}; +use serde::ser::{Serialize, Serializer}; +use serde::de::{self, Deserialize, Deserializer, Visitor}; + +use std::fmt; +use std::marker::PhantomData; + +use super::{LazyCell, AtomicLazyCell}; + +impl<T: Serialize> Serialize for LazyCell<T> { + fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> { + match self.borrow() { + Some(val) => serializer.serialize_some(val), + None => serializer.serialize_none() + } + } +} + + +impl<T: Serialize> Serialize for AtomicLazyCell<T> { + fn serialize<S: Serializer>(&self, serializer: S) -> Result<S::Ok, S::Error> { + match self.borrow() { + Some(val) => serializer.serialize_some(val), + None => serializer.serialize_none() + } + } +} + +struct LazyCellVisitor<T>(PhantomData<*const T>); +impl<'de, T: Deserialize<'de>> Visitor<'de> for LazyCellVisitor<T> { + type Value = LazyCell<T>; + + fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + formatter.write_str("a LazyCell") + } + + fn visit_some<D: Deserializer<'de>>(self, deserializer: D) -> Result<Self::Value, D::Error> { + let mut cell = LazyCell::new(); + cell.replace(T::deserialize(deserializer)?); + Ok(cell) + } + + fn visit_none<E: de::Error>(self) -> Result<Self::Value, E> { + Ok(LazyCell::new()) + } +} + +impl<'de, T: Deserialize<'de>> Deserialize<'de> for LazyCell<T> { + fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> { + deserializer.deserialize_option(LazyCellVisitor(PhantomData)) + } +} + + +struct AtomicLazyCellVisitor<T>(PhantomData<*const T>); +impl<'de, T: Deserialize<'de>> Visitor<'de> for AtomicLazyCellVisitor<T> { + type Value = AtomicLazyCell<T>; + + fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result { + formatter.write_str("an AtomicLazyCell") + } + + fn visit_some<D: Deserializer<'de>>(self, deserializer: D) -> Result<Self::Value, D::Error> { + let mut cell = AtomicLazyCell::new(); + cell.replace(T::deserialize(deserializer)?); + Ok(cell) + } + + fn visit_none<E: de::Error>(self) -> Result<Self::Value, E> { + Ok(AtomicLazyCell::new()) + } +} + + +impl<'de, T: Deserialize<'de>> Deserialize<'de> for AtomicLazyCell<T> { + fn deserialize<D: Deserializer<'de>>(deserializer: D) -> Result<Self, D::Error> { + deserializer.deserialize_option(AtomicLazyCellVisitor(PhantomData)) + } +} |