#pin #macros #attribute

no-std pin-project

A crate for safe and ergonomic pin-projection

60 releases (7 stable)

1.0.6 Mar 25, 2021
1.0.4 Jan 9, 2021
1.0.2 Nov 18, 2020
0.4.28 Mar 28, 2021
0.3.2 Mar 30, 2019

#1 in Rust patterns

Download history 256750/week @ 2020-12-20 247139/week @ 2020-12-27 391228/week @ 2021-01-03 422085/week @ 2021-01-10 390111/week @ 2021-01-17 430881/week @ 2021-01-24 448893/week @ 2021-01-31 456246/week @ 2021-02-07 438092/week @ 2021-02-14 417127/week @ 2021-02-21 417771/week @ 2021-02-28 397526/week @ 2021-03-07 394429/week @ 2021-03-14 407889/week @ 2021-03-21 421606/week @ 2021-03-28 384325/week @ 2021-04-04

1,733,989 downloads per month
Used in 4,695 crates (281 directly)

Apache-2.0 OR MIT

63KB
205 lines

pin-project

crates.io docs.rs license rustc build status

A crate for safe and ergonomic pin-projection.

Usage

Add this to your Cargo.toml:

[dependencies]
pin-project = "1"

Compiler support: requires rustc 1.37+

Examples

#[pin_project] attribute creates projection types covering all the fields of struct or enum.

use pin_project::pin_project;
use std::pin::Pin;

#[pin_project]
struct Struct<T, U> {
    #[pin]
    pinned: T,
    unpinned: U,
}

impl<T, U> Struct<T, U> {
    fn method(self: Pin<&mut Self>) {
        let this = self.project();
        let _: Pin<&mut T> = this.pinned; // Pinned reference to the field
        let _: &mut U = this.unpinned; // Normal reference to the field
    }
}

code like this will be generated

To use #[pin_project] on enums, you need to name the projection type returned from the method.

use pin_project::pin_project;
use std::pin::Pin;

#[pin_project(project = EnumProj)]
enum Enum<T, U> {
    Pinned(#[pin] T),
    Unpinned(U),
}

impl<T, U> Enum<T, U> {
    fn method(self: Pin<&mut Self>) {
        match self.project() {
            EnumProj::Pinned(x) => {
                let _: Pin<&mut T> = x;
            }
            EnumProj::Unpinned(y) => {
                let _: &mut U = y;
            }
        }
    }
}

code like this will be generated

See documentation for more details, and see examples directory for more examples and generated code.

Related Projects

  • pin-project-lite: A lightweight version of pin-project written with declarative macros.

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 the work by you, as defined in the Apache-2.0 license, shall be dual licensed as above, without any additional terms or conditions.

Dependencies

~355–780KB
~19K SLoC