#pin #macros #attribute

macro no-std pin-project-internal

Implementation detail of the pin-project crate

50 releases (8 stable)

1.0.7 Apr 16, 2021
1.0.6 Mar 25, 2021
1.0.5 Feb 3, 2021
1.0.2 Nov 18, 2020
0.4.6 Nov 20, 2019

#413 in Rust patterns

Download history 415153/week @ 2021-01-07 395088/week @ 2021-01-14 415407/week @ 2021-01-21 439892/week @ 2021-01-28 452338/week @ 2021-02-04 443173/week @ 2021-02-11 429330/week @ 2021-02-18 424671/week @ 2021-02-25 401386/week @ 2021-03-04 398667/week @ 2021-03-11 393063/week @ 2021-03-18 440566/week @ 2021-03-25 391231/week @ 2021-04-01 426439/week @ 2021-04-08 422763/week @ 2021-04-15 411760/week @ 2021-04-22

1,800,049 downloads per month
Used in 4,829 crates (via pin-project)

Apache-2.0 OR MIT

98KB
1.5K SLoC

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

~345–770KB
~19K SLoC