commit	47965e1155a6f280e3916c1f4a0c120f2e9849ef	[log] [tgz]
author	Xin Li <delphij@google.com>	Mon Nov 23 11:30:34 2020 -0800
committer	Xin Li <delphij@google.com>	Mon Nov 23 11:30:34 2020 -0800
tree	62e1173064643de076d5710596b3cd6d390f4d00
parent	c686a2052dc6c290860669392cdc7dceaffaf41a [diff]
parent	94ccfc7e8bf5a60afbf299bc8ef15babceffa8ef [diff]

tree: 62e1173064643de076d5710596b3cd6d390f4d00

README.md

pin-project

A crate for safe and ergonomic pin-projection.

Usage

Add this to your Cargo.toml:

[dependencies]
pin-project = "1"

The current pin-project requires Rust 1.37 or later.

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.

Contribution

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.