ref-cast-1.0.3/.cargo_vcs_info.json0000644000000001121374641364100126020ustar { "git": { "sha1": "e14a8d9cccf3bb3445c9e6326b7b8908b9746dc6" } } ref-cast-1.0.3/.github/FUNDING.yml010064400017500001750000000000201367150311400145460ustar 00000000000000github: dtolnay ref-cast-1.0.3/.github/workflows/ci.yml010064400017500001750000000011031365432736000161170ustar 00000000000000name: CI on: push: pull_request: schedule: [cron: "40 1 * * *"] jobs: test: name: Rust ${{matrix.rust}} runs-on: ubuntu-latest strategy: fail-fast: false matrix: rust: [nightly, beta, stable, 1.36.0] steps: - uses: actions/checkout@v2 - uses: dtolnay/rust-toolchain@master with: toolchain: ${{matrix.rust}} - run: cargo test msrv: name: Rust 1.31.0 runs-on: ubuntu-latest steps: - uses: actions/checkout@v2 - uses: dtolnay/rust-toolchain@1.31.0 - run: cargo check ref-cast-1.0.3/.gitignore010064400017500001750000000000221346021544600133670ustar 00000000000000target Cargo.lock ref-cast-1.0.3/Cargo.toml0000644000000021141374641364100106040ustar # 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] edition = "2018" name = "ref-cast" version = "1.0.3" authors = ["David Tolnay "] description = "Safely cast &T to &U where the struct U contains a single field of type T." documentation = "https://docs.rs/ref-cast" readme = "README.md" license = "MIT OR Apache-2.0" repository = "https://github.com/dtolnay/ref-cast" [package.metadata.docs.rs] targets = ["x86_64-unknown-linux-gnu"] [dependencies.ref-cast-impl] version = "=1.0.3" [dev-dependencies.rustversion] version = "1.0" [dev-dependencies.trybuild] version = "1.0.32" features = ["diff"] ref-cast-1.0.3/Cargo.toml.orig010066400017500001750000000012111374641356100142760ustar 00000000000000[package] name = "ref-cast" version = "1.0.3" # remember to update html_root_url authors = ["David Tolnay "] edition = "2018" license = "MIT OR Apache-2.0" description = "Safely cast &T to &U where the struct U contains a single field of type T." repository = "https://github.com/dtolnay/ref-cast" documentation = "https://docs.rs/ref-cast" readme = "README.md" [dependencies] ref-cast-impl = { version = "=1.0.3", path = "derive" } [dev-dependencies] rustversion = "1.0" trybuild = { version = "1.0.32", features = ["diff"] } [workspace] members = ["derive"] [package.metadata.docs.rs] targets = ["x86_64-unknown-linux-gnu"] ref-cast-1.0.3/LICENSE-APACHE010064400017500001750000000251371346021544600133410ustar 00000000000000 Apache License Version 2.0, January 2004 http://www.apache.org/licenses/ TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION 1. 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See the License for the specific language governing permissions and limitations under the License. ref-cast-1.0.3/LICENSE-MIT010064400017500001750000000020571346021544600130450ustar 00000000000000Copyright (c) 2016 The Rust Project Developers 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. 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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. ref-cast-1.0.3/README.md010064400017500001750000000105001367133513700126640ustar 00000000000000RefCast ======= [github](https://github.com/dtolnay/ref-cast) [crates.io](https://crates.io/crates/ref-cast) [docs.rs](https://docs.rs/ref-cast) [build status](https://github.com/dtolnay/ref-cast/actions?query=branch%3Amaster) Safely cast `&T` to `&U` where the struct `U` contains a single field of type `T`. ```toml [dependencies] ref-cast = "1.0" ``` ## Basic example ```rust use ref_cast::RefCast; #[derive(RefCast)] #[repr(transparent)] struct U(String); fn main() { let s = String::new(); // Safely cast from `&String` to `&U`. let u = U::ref_cast(&s); } ``` Note that either of `#[repr(C)]` or `#[repr(transparent)]` is required in order for the conversion to be sound. The derive macro will refuse to compile if neither is present. ## Realistic example Suppose we have a multidimensional array represented in a flat buffer in row-major order for performance reasons, but we want to expose an indexing operation that works in column-major order because it is more intuitive in the context of our application. ```rust const MAP_WIDTH: usize = 4; struct Tile(u8); struct TileMap { storage: Vec, } // `tilemap[x][y]` should give us `tilemap.storage[y * MAP_WIDTH + x]`. ``` The signature of the [`Index`] trait in Rust is such that the output is forced to be borrowed from the type being indexed. So something like the following is not going to work. [`Index`]: https://doc.rust-lang.org/std/ops/trait.Index.html ```rust struct Column<'a> { tilemap: &'a TileMap, x: usize, } // Does not work! The output of Index must be a reference that is // borrowed from self. Here the type Column is not a reference. impl Index for TileMap { fn index(&self, x: usize) -> Column { assert!(x < MAP_WIDTH); Column { tilemap: self, x } } } impl<'a> Index for Column<'a> { fn index(&self, y: usize) -> &Tile { &self.tilemap.storage[y * MAP_WIDTH + self.x] } } ``` Here is a working approach using `RefCast`. ```rust #[derive(RefCast)] #[repr(transparent)] struct Strided([Tile]); // Implement `tilemap[x][y]` as `tilemap[x..][y * MAP_WIDTH]`. impl Index for TileMap { type Output = Strided; fn index(&self, x: usize) -> &Self::Output { assert!(x < MAP_WIDTH); Strided::ref_cast(&self.storage[x..]) } } impl Index for Strided { type Output = Tile; fn index(&self, y: usize) -> &Self::Output { &self.0[y * MAP_WIDTH] } } ```
#### License Licensed under either of Apache License, Version 2.0 or MIT license at your option.
Unless you explicitly state otherwise, any contribution intentionally submitted for inclusion in this crate by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions. ref-cast-1.0.3/src/lib.rs010064400017500001750000000127241374641355400133250ustar 00000000000000//! [![github]](https://github.com/dtolnay/ref-cast) [![crates-io]](https://crates.io/crates/ref-cast) [![docs-rs]](https://docs.rs/ref-cast) //! //! [github]: https://img.shields.io/badge/github-8da0cb?style=for-the-badge&labelColor=555555&logo=github //! [crates-io]: https://img.shields.io/badge/crates.io-fc8d62?style=for-the-badge&labelColor=555555&logo=rust //! [docs-rs]: https://img.shields.io/badge/docs.rs-66c2a5?style=for-the-badge&labelColor=555555&logoColor=white&logo=data:image/svg+xml;base64,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 //! //!
//! //! This crate provides a derive macro for generating safe conversions from `&T` //! to `&U` where the struct `U` contains a single field of type `T`. //! //! # Basic example //! //! ``` //! use ref_cast::RefCast; //! //! #[derive(RefCast)] //! #[repr(transparent)] //! struct U(String); //! //! fn main() { //! let s = String::new(); //! //! // Safely cast from `&String` to `&U`. //! let u = U::ref_cast(&s); //! } //! ``` //! //! Note that either of `#[repr(C)]` or `#[repr(transparent)]` is required in //! order for the conversion to be sound. The derive macro will refuse to //! compile if neither is present. //! //! # Realistic example //! //! Suppose we have a multidimensional array represented in a flat buffer in //! row-major order for performance reasons, but we want to expose an indexing //! operation that works in column-major order because it is more intuitive in //! the context of our application. //! //! ``` //! const MAP_WIDTH: usize = 4; //! //! struct Tile(u8); //! //! struct TileMap { //! storage: Vec, //! } //! //! // `tilemap[x][y]` should give us `tilemap.storage[y * MAP_WIDTH + x]`. //! ``` //! //! The signature of the [`Index`] trait in Rust is such that the output is //! forced to be borrowed from the type being indexed. So something like the //! following is not going to work. //! //! [`Index`]: https://doc.rust-lang.org/std/ops/trait.Index.html //! //! ``` //! # const MAP_WIDTH: usize = 4; //! # //! # struct Tile(u8); //! # //! # struct TileMap { //! # storage: Vec, //! # } //! # //! struct Column<'a> { //! tilemap: &'a TileMap, //! x: usize, //! } //! //! # mod index1 { //! # use super::{TileMap, Column, MAP_WIDTH}; //! # //! # trait Index { //! # fn index(&self, idx: Idx) -> Column; //! # } //! # //! // Does not work! The output of Index must be a reference that is //! // borrowed from self. Here the type Column is not a reference. //! impl Index for TileMap { //! fn index(&self, x: usize) -> Column { //! assert!(x < MAP_WIDTH); //! Column { tilemap: self, x } //! } //! } //! # } //! //! # mod index2 { //! # use super::{Column, Tile, MAP_WIDTH}; //! # use std::ops::Index; //! # //! impl<'a> Index for Column<'a> { //! # type Output = Tile; //! fn index(&self, y: usize) -> &Tile { //! &self.tilemap.storage[y * MAP_WIDTH + self.x] //! } //! } //! # } //! # //! # fn main() {} //! ``` //! //! Here is a working approach using `RefCast`. //! //! ``` //! # use ref_cast::RefCast; //! # use std::ops::Index; //! # //! # const MAP_WIDTH: usize = 4; //! # //! # struct Tile(u8); //! # //! # struct TileMap { //! # storage: Vec, //! # } //! # //! #[derive(RefCast)] //! #[repr(transparent)] //! struct Strided([Tile]); //! //! // Implement `tilemap[x][y]` as `tilemap[x..][y * MAP_WIDTH]`. //! impl Index for TileMap { //! type Output = Strided; //! fn index(&self, x: usize) -> &Self::Output { //! assert!(x < MAP_WIDTH); //! Strided::ref_cast(&self.storage[x..]) //! } //! } //! //! impl Index for Strided { //! type Output = Tile; //! fn index(&self, y: usize) -> &Self::Output { //! &self.0[y * MAP_WIDTH] //! } //! } //! ``` #![doc(html_root_url = "https://docs.rs/ref-cast/1.0.3")] #![no_std] mod trivial; pub use ref_cast_impl::RefCast; /// Safely cast `&T` to `&U` where the struct `U` contains a single field of /// type `T`. /// /// ``` /// # use ref_cast::RefCast; /// # /// // `&String` can be cast to `&U`. /// #[derive(RefCast)] /// #[repr(transparent)] /// struct U(String); /// /// // `&T` can be cast to `&V`. /// #[derive(RefCast)] /// #[repr(transparent)] /// struct V { /// t: T, /// } /// ``` /// /// See the crate-level documentation for usage examples! pub trait RefCast { type From: ?Sized; fn ref_cast(from: &Self::From) -> &Self; fn ref_cast_mut(from: &mut Self::From) -> &mut Self; } // Not public API. #[doc(hidden)] pub mod private { pub use crate::trivial::assert_trivial; } ref-cast-1.0.3/src/trivial.rs010064400017500001750000000002431356166464600142270ustar 00000000000000use core::marker::PhantomData; pub trait Trivial {} impl Trivial for () {} impl Trivial for PhantomData {} pub fn assert_trivial() {} ref-cast-1.0.3/tests/compiletest.rs010066400017500001750000000002141351054112700154360ustar 00000000000000#[rustversion::attr(not(nightly), ignore)] #[test] fn ui() { let t = trybuild::TestCases::new(); t.compile_fail("tests/ui/*.rs"); } ref-cast-1.0.3/tests/test_trivial.rs010064400017500001750000000016571356167011200156340ustar 00000000000000use ref_cast::RefCast; use std::marker::PhantomData; type Marker = PhantomData; #[derive(RefCast)] #[repr(transparent)] pub struct ImplicitUnit { pub value: usize, _private: (), } #[derive(RefCast)] #[repr(transparent)] pub struct ImplicitPhantomData { pub value: T, pub marker: PhantomData, } #[derive(RefCast)] #[repr(transparent)] pub struct ExplicitTrivial { pub value: usize, #[trivial] pub marker: Marker, } #[derive(RefCast)] #[repr(C)] pub struct Override { #[trivial] pub first: PhantomData, pub second: PhantomData, } #[derive(RefCast)] #[repr(transparent)] pub struct Unsized<'a> { pub marker: PhantomData<&'a str>, pub value: str, } #[test] fn test_trivial() { ImplicitUnit::ref_cast(&0); ImplicitPhantomData::ref_cast(&0); ExplicitTrivial::ref_cast(&0); Override::::ref_cast(&PhantomData::); Unsized::ref_cast("..."); } ref-cast-1.0.3/tests/ui/no-repr.rs010064400017500001750000000001301346021544600151060ustar 00000000000000use ref_cast::RefCast; #[derive(RefCast)] struct Test { s: String, } fn main() {} ref-cast-1.0.3/tests/ui/no-repr.stderr010066400017500001750000000004001371410514400157620ustar 00000000000000error: RefCast trait requires #[repr(C)] or #[repr(transparent)] --> $DIR/no-repr.rs:3:10 | 3 | #[derive(RefCast)] | ^^^^^^^ | = note: this error originates in a derive macro (in Nightly builds, run with -Z macro-backtrace for more info) ref-cast-1.0.3/tests/ui/not-trivial.rs010064400017500001750000000002051356166757300160150ustar 00000000000000use ref_cast::RefCast; #[derive(RefCast)] #[repr(C)] struct Test { one: String, #[trivial] two: String, } fn main() {} ref-cast-1.0.3/tests/ui/not-trivial.stderr010066400017500001750000000006101374641314200166600ustar 00000000000000error[E0277]: the trait bound `String: ref_cast::trivial::Trivial` is not satisfied --> $DIR/not-trivial.rs:8:10 | 8 | two: String, | ^^^^^^ the trait `ref_cast::trivial::Trivial` is not implemented for `String` | ::: $WORKSPACE/src/trivial.rs | | pub fn assert_trivial() {} | ------- required by this bound in `assert_trivial`