#count #macro #compile-time #procedural

macro count-macro

A simple Rust macro to perform compile time counting

5 releases

0.2.2 May 21, 2022
0.2.1 Feb 22, 2022
0.2.0 Feb 21, 2022
0.1.1 Jan 9, 2022
0.1.0 Jan 9, 2022

#100 in #count

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179 downloads per month
Used in 2 crates (via bool_vec)

MIT license

10KB
107 lines

Count macro

A macro to allow for compile time counting

How to use this

Every instance of _int_ will be replaced with either a literal or an ident.

count_macro::count will panic in debug mode if counter exceeds usize.

If you wish to wrap to 0, please use count_macro::wrapping_count.

Examples

Ident to literal

use count_macro::count;

let a = count!(vec![_int_, _int_, _int_]);
assert_eq!(a, vec![0, 1, 2]);

Ident to ident

use count_macro::count;

count! {
    let a_int_ = "Hello";
    let a_int_ = "World";
}

assert_eq!(a0, "Hello");
assert_eq!(a1, "World");

In macro

use count_macro::count;

macro_rules! my_macro {
    ($($v:expr),*) => {
        count!{
            $(
                let _ = $v; // Ignoring $v

                println!("{}", _int_);
            )*
        }
    };
}

my_macro!('@', '@', '@', '@'); // Will print from 0 to 3

Multiple counters

with _int_countername_ you'll be able to create a new counter called "countername".

This won't be incremented by _int_ or any other counter such as _int_0_ or _int_x_.

use count_macro::count;

// With two different counters
// _int_ does not increment _int_name_
count! {
    let a_int_ = _int_name_;
    let a_int_ = _int_name_;
    let a_int_ = _int_name_;
}

assert_eq!(a0, 0);
assert_eq!(a1, 1);
assert_eq!(a2, 2);

Dependencies

~2.1–3MB
~53K SLoC