A macro for wrapping arithmetic
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 for the motivation behind this crate.
Note: This crate uses internal compiler APIs, and so requires the Nightly version of Rust.
Add this to your Cargo.toml
:
wrapping_macros = "*"
#![feature(plugin)]
#![plugin(wrapping_macros)]
fn main() {
let mut sum = 0u8;
for x in 0u8..50 {
wrapping! {
sum += x;
}
}
}
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:
let x = 41i32;
wrapping! {
println!("The answer is {}", x + 1); //~ ERROR
}
Instead, move the macro call out of the block:
let x = 41i32;
println!("The answer is {}", wrapping! { x + 1 });