https://github.com/lambda-fairy/wrapping_macros

:gift_heart: A macro for wrapping arithmetic
https://github.com/lambda-fairy/wrapping_macros

macros rust

Last synced: 8 months ago
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:gift_heart: A macro for wrapping arithmetic

• Host: GitHub
• URL: https://github.com/lambda-fairy/wrapping_macros
• Owner: lambda-fairy
• Created: 2015-03-31T06:51:57.000Z (over 11 years ago)
• Default Branch: master
• Last Pushed: 2017-03-12T03:36:45.000Z (over 9 years ago)
• Last Synced: 2025-04-09T10:48:43.215Z (over 1 year ago)
• Topics: macros, rust
• Language: Rust
• Homepage:
• Size: 23.4 KB
• Stars: 8
• Watchers: 2
• Forks: 1
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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README

          
# wrapping_macros [![Build Status](https://img.shields.io/travis/lfairy/wrapping_macros.svg)](http://travis-ci.org/lfairy/wrapping_macros) [![Cargo](https://img.shields.io/crates/v/wrapping_macros.svg)](https://crates.io/crates/wrapping_macros)

A macro for wrapping arithmetic.

Any code within a `wrapping! { .. }` block will be transformed as follows:

* `a + b` becomes `a.wrapping_add(b)`. Similarly for `-`, `*`, `/`, `%`, `<<`, `>>`.

* `a += b` becomes `a = a.wrapping_add(b)`. Similarly for `-=`, `*=`, `/=`, `%=`, `<<=`, `>>=`.

* `-a` becomes `a.wrapping_neg()`.

See [this Internals thread][1] for the motivation behind this crate.

[1]: http://internals.rust-lang.org/t/ergonomics-of-wrapping-operations/1756?u=lfairy

**Note:** This crate uses internal compiler APIs, and so requires the Nightly version of Rust.

## Cargo

Add this to your `Cargo.toml`:

```toml

wrapping_macros = "*"

```

## Example

```rust

#![feature(plugin)]

#![plugin(wrapping_macros)]

fn main() {

    let mut sum = 0u8;

    for x in 0u8..50 {

        wrapping! {

            sum += x;

        }

    }

}

```

## Caveats

*   This crate uses unstable APIs, and will only work on Rust Nightly.

*   You cannot nest another macro invocation within a `wrapping!` block. For example, this will not work:

    ```rust

    let x = 41i32;

    wrapping! {

        println!("The answer is {}", x + 1);  //~ ERROR

    }

    ```

    Instead, move the macro call out of the block:

    ```rust

    let x = 41i32;

    println!("The answer is {}", wrapping! { x + 1 });

    ```