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petgraph / fixedbitset

A simple bitset container for Rust
https://docs.rs/fixedbitset/
Apache License 2.0
127 stars 47 forks source link

Make a version of the fixed bitset actually fixed at compile time #82

Closed EriKWDev closed 1 year ago

EriKWDev commented 1 year ago

I don't know what part of this implementation is "Fixed" since it seems like the bitsets can grow at will and is implemented using a Vec.

It would be cool to instead have the size be known at compile time which would allow allocation-less bitsets:

type Block = usize;
pub struct CTFixedBitSet<const BLOCKS: usize> {
    pub blocks: [Block; BLOCKS],
    pub length: usize,
}

While this would make the Api dependant on blocks instead of the number of bits which might be confusing to a new user, I feel like it could improve performance. Perhaps a macro could be used to calculate the value based on bits? Don't know if that's possible without a proc-macro though.

let mut my_bitset = bitset!(128); // Would create a CTFixedBitSet<4> on 32-bit platforms and CTFixedBitSet<2> on 64-bit if Block is usize
jrraymond commented 1 year ago

I think this is a useful idea, but if implemented it should belong in a separate crate.

EriKWDev commented 1 year ago

As I will be developing this for my own needs anyways I will post it as a crate once a bit further along. Any name-suggestions? xP

I feel like a fixed bitset should preferably have had the name of this crate instead and not the other way around...

jrraymond commented 1 year ago

I've heard that is one of the 2 hardest problems in computer science ....

unlimitedsola commented 1 week ago

Hi, I'm also confused about why this crate has "fixed" in its name. Could we have some explanation on why it was named this way in the crate documentation or README.md where people can find the answer easily?