https://github.com/ink-feather-org/const-closure-rs

Helpers for creating const callable closures.
https://github.com/ink-feather-org/const-closure-rs

Last synced: 2 days ago
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Helpers for creating const callable closures.

• Host: GitHub
• URL: https://github.com/ink-feather-org/const-closure-rs
• Owner: ink-feather-org
• License: apache-2.0
• Created: 2022-09-13T16:42:07.000Z (over 2 years ago)
• Default Branch: master
• Last Pushed: 2024-12-14T22:44:38.000Z (14 days ago)
• Last Synced: 2024-12-23T17:48:06.289Z (5 days ago)
• Language: Rust
• Homepage:
• Size: 52.7 KB
• Stars: 0
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE-APACHE

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README

        
# const-closure

[![docs.rs](https://docs.rs/const-closure/badge.svg)](https://docs.rs/const-closure)

[![crates.io](https://img.shields.io/crates/v/const-closure.svg)](https://crates.io/crates/const-closure)

[![rustc](https://img.shields.io/badge/rustc-nightly-lightgrey)](https://doc.rust-lang.org/nightly/std/)

# THIS CRATE IS BROKEN - Archive Note

The last tested working rust version is `1.71.0-nightly (nightly-2023-04-18)`.

Most const traits have been removed from the standard library.

Once they are back this crate might make a return if it is still needed.

## Description

This crate allows you to create types which represent closures in const contexts.

To do this simply create an instance of the provided closure helper: `ConstClosure`

with the associated `new` function.

A closure helper instance gets the data to capture as a tuple of same ownership (Owned, Mut or ref) and the implementation function to execute.

The implementation function must be a `const fn` that gets the captured state (a tuple of: owned values for `FnOnce`, `&mut` for `FnMut` and `&` for `Fn`)

and a tuple representing the arguments of the closure.

A closure helper instance returns the return value of the closure function on call.

## Example

```rust

#![feature(const_trait_impl)]

#![feature(const_mut_refs)] // Only required for the FnMut example

use const_closure::ConstClosure;

// FnOnce:

const _: () = {

  const fn imp((state,): (i32,), (arg,): (i32,)) -> i32 {

    state + arg

  }

  let cl = ConstClosure::new((5,), imp);

  assert!(7 == cl(2));

};

// FnMut:

const _: () = {

  const fn imp((state,): (&mut i32,), (arg,): (i32,)) -> i32 {

    *state += arg;

    *state

  }

  let mut i = 5;

  let mut cl = ConstClosure::new((&mut i,), imp);

  assert!(7 == cl(2));

  assert!(8 == cl(1));

};

// Fn:

const _: () = {

  const fn imp((state,): (&i32,), (arg,): (i32,)) -> i32 {

    *state + arg

  }

  let i = 5;

  let mut cl = ConstClosure::new((&i,), imp);

  assert!(7 == cl(2));

  assert!(8 == cl(3));

  assert!(6 == cl(1));

};

```

Note: The `const_closure` macro has been removed in favour of the new generic based approach.

Authors

-------

[raldone01](https://github.com/raldone01) and [onestacked](https://github.com/chriss0612) are the primary authors and maintainers of this library.

License

-------

This project is released under either:

- [MIT License](https://github.com/ink-feather-org/const-closure-rs/blob/master/LICENSE-MIT)

- [Apache License (Version 2.0)](https://github.com/ink-feather-org/const-closure-rs/blob/master/LICENSE-APACHE)

at your choosing.

### 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.