https://github.com/taiki-e/pin-project

A crate for safe and ergonomic pin-projection.
https://github.com/taiki-e/pin-project

no-std proc-macro rust

Last synced: 14 days ago
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A crate for safe and ergonomic pin-projection.

• Host: GitHub
• URL: https://github.com/taiki-e/pin-project
• Owner: taiki-e
• License: apache-2.0
• Created: 2019-01-08T14:42:10.000Z (almost 6 years ago)
• Default Branch: main
• Last Pushed: 2024-10-24T17:05:12.000Z (20 days ago)
• Last Synced: 2024-10-25T06:28:15.122Z (19 days ago)
• Topics: no-std, proc-macro, rust
• Language: Rust
• Homepage: https://docs.rs/pin-project
• Size: 2.3 MB
• Stars: 606
• Watchers: 10
• Forks: 33
• Open Issues: 3
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE-APACHE

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README

        
# pin-project

[![crates.io](https://img.shields.io/crates/v/pin-project?style=flat-square&logo=rust)](https://crates.io/crates/pin-project)

[![docs.rs](https://img.shields.io/badge/docs.rs-pin--project-blue?style=flat-square&logo=docs.rs)](https://docs.rs/pin-project)

[![license](https://img.shields.io/badge/license-Apache--2.0_OR_MIT-blue?style=flat-square)](#license)

[![msrv](https://img.shields.io/badge/msrv-1.56-blue?style=flat-square&logo=rust)](https://www.rust-lang.org)

[![github actions](https://img.shields.io/github/actions/workflow/status/taiki-e/pin-project/ci.yml?branch=main&style=flat-square&logo=github)](https://github.com/taiki-e/pin-project/actions)

A crate for safe and ergonomic [pin-projection].

## Usage

Add this to your `Cargo.toml`:

```toml

[dependencies]

pin-project = "1"

```

## Examples

[`#[pin_project]`][`pin_project`] attribute creates projection types

covering all the fields of struct or enum.

```rust

use std::pin::Pin;

use pin_project::pin_project;

#[pin_project]

struct Struct {

    #[pin]

    pinned: T,

    unpinned: U,

}

impl Struct {

    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*][struct-default-expanded]

To use `#[pin_project]` on enums, you need to name the projection type

returned from the method.

```rust

use std::pin::Pin;

use pin_project::pin_project;

#[pin_project(project = EnumProj)]

enum Enum {

    Pinned(#[pin] T),

    Unpinned(U),

}

impl Enum {

    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*][enum-default-expanded]

See [`#[pin_project]`][`pin_project`] attribute 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.

[enum-default-expanded]: https://github.com/taiki-e/pin-project/blob/HEAD/examples/enum-default-expanded.rs

[examples]: https://github.com/taiki-e/pin-project/blob/HEAD/examples/README.md

[pin-project-lite]: https://github.com/taiki-e/pin-project-lite

[pin-projection]: https://doc.rust-lang.org/std/pin/index.html#projections-and-structural-pinning

[struct-default-expanded]: https://github.com/taiki-e/pin-project/blob/HEAD/examples/struct-default-expanded.rs

[`pin_project`]: https://docs.rs/pin-project/latest/pin_project/attr.pin_project.html

## License

Licensed under either of [Apache License, Version 2.0](LICENSE-APACHE) or

[MIT license](LICENSE-MIT) 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.