# pin-project
[](https://travis-ci.org/taiki-e/pin-project)
[](https://crates.io/crates/pin-project/)
[](https://docs.rs/pin-project/)
[](https://crates.io/crates/pin-project/)
An attribute that would create a projection struct covering all the fields.
[Documentation](https://docs.rs/pin-project/)
## Usage
Add this to your `Cargo.toml`:
```toml
[dependencies]
pin-project = "0.1.8"
```
Now, you can use pin-project:
```rust
use pin_project::unsafe_project;
```
The current version of pin-project requires Rust 1.33 or later.
## Examples
For structs:
```rust
use pin_project::unsafe_project;
use std::pin::Pin;
#[unsafe_project(Unpin)]
struct Foo<T, U> {
#[pin]
future: T,
field: U,
}
impl<T, U> Foo<T, U> {
fn baz(mut self: Pin<&mut Self>) {
let this = self.project();
let _: Pin<&mut T> = this.future; // Pinned reference to the field
let _: &mut U = this.field; // Normal reference to the field
}
}
// Automatically create the appropriate conditional Unpin implementation.
// impl<T, U> Unpin for Foo<T, U> where T: Unpin {} // Conditional Unpin impl
```
For enums:
```rust
use pin_project::{project, unsafe_project};
use std::pin::Pin;
#[unsafe_project(Unpin)]
enum Foo<T, U> {
Future(#[pin] T),
Done(U),
}
impl<T, U> Foo<T, U> {
#[project] // Nightly does not need a dummy attribute to the function.
fn baz(mut self: Pin<&mut Self>) {
#[project]
match self.project() {
Foo::Future(future) => {
let _: Pin<&mut T> = future;
}
Foo::Done(value) => {
let _: &mut U = value;
}
}
}
}
// Automatically create the appropriate conditional Unpin implementation.
// impl<T, U> Unpin for Foo<T, U> where T: Unpin {} // Conditional Unpin impl
```
See the [documentation](https://docs.rs/pin-project/) for more details.
## License
Licensed under either of
* Apache License, Version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or <http://www.apache.org/licenses/LICENSE-2.0>)
* MIT license ([LICENSE-MIT](LICENSE-MIT) or <http://opensource.org/licenses/MIT>)
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.