#boolean #single #vec #byte #bool #store #expose

bool_vec

A crates that exposes a vector called BoolVec which allows you to store a boolean in a single bit

2 unstable releases

0.2.1 May 25, 2023
0.2.0 May 24, 2023
0.1.2 May 24, 2023
0.1.1 May 24, 2023
0.1.0 May 24, 2023

#156 in Value formatting

43 downloads per month
Used in sat_lab

MIT license

22KB
237 lines

Description

This library exposes a vector called BoolVec which allows you to store 8 booleans in a single byte. Basically a boolean only occupies a single bit.

How to use

Please check out the documentation on docs.rs and the examples below

Examples

Initializing an empty BoolVec

To create a new BoolVec you can use either BoolVec::new() or BoolVec::default():

use bool_vec::BoolVec;

let bv1 = BoolVec::new();
let bv2 = BoolVec::default();

assert_eq!(bv1, bv2);

Or, if you already know your desired capacity you can use BoolVec::with_capacity(cap):

use bool_vec::BoolVec;

let bv = BoolVec::with_capacity(3);

assert!(bv.capacity() > 0);

Initializing BoolVec from a Vec or slice

You can initialize a BoolVec from anything that implements AsRef<[bool]> with BoolVec::from(S). This includes vectors and slices:

use bool_vec::BoolVec;

let bv1 = BoolVec::from([true, false, true]);
let bv2 = BoolVec::from(vec![true, false, true]);

assert_eq!(bv1, bv2);

Initializing using boolvec![] macro

Just like Vec with the vec![] macro, you can initialize a BoolVec with the boolvec![] macro:

use bool_vec::{BoolVec, boolvec};

let bv1 = BoolVec::new();
let bv2 = boolvec![];

assert_eq!(bv1, bv2);

let bv3 = boolvec![true, true, true];
let bv4 = boolvec![true; 3];

assert_eq!(bv3, bv4);

Pushing values into the BoolVec

You can push booleans to the back of the BoolVec just like you would with a normal Vec:

use bool_vec::boolvec;

let mut bv = boolvec![true, false, true];

bv.push(true);

assert_eq!(bv, boolvec![true, false, true, true]);

Popping values off the BoolVec

Again, just like with a normal Vec, you can remove items at the end of a BoolVec with BoolVec.pop(). Do note that just like with Vec, removed values will be returned. If no value is found, None is returned instead:

use bool_vec::boolvec;

let mut bv1 = boolvec![true, false, true];
let mut bv2 = boolvec![];

assert_eq!(bv1.pop(), Some(true));
assert_eq!(bv2.pop(), None);

assert_eq!(bv1, boolvec![true, false]);

Getting values from a BoolVec

You can get a value from a BoolVec with the BoolVec.get(index) method. None will be returned if index is invalid:

use bool_vec::boolvec;

let bv = boolvec![true, false, true];

assert_eq!(bv.get(1), Some(false));
assert_eq!(bv.get(3), None);

Changing values in a BoolVec

You can change the value of any bool inside a BoolVec with the BoolVec.set(index, value) method. Just like with BoolVec.get(index), None will be returned if index is invalid.

use bool_vec::boolvec;

let mut bv = boolvec![true, false, true];

assert_eq!(bv.set(0, false), Some(()) );
assert_eq!(bv.get(0), Some(false));

assert_eq!(bv.set(3, false), None);

Negating values in a BoolVec

Negating a value is simple with the BoolVec.negate(index) method. This will update your value in the BoolVec, changing it either from true to false, or from false to true, and then return the negated value. Again, None will be returned if index is invalid.

use bool_vec::boolvec;

let mut bv = boolvec![true, false, true];

assert_eq!(bv.negate(0), Some(false));
assert_eq!(bv.get(0), Some(false));

assert_eq!(bv.negate(3), None);

Getting a Vec from a BoolVec

You can get a Vec<bool> from a BoolVec with the BoolVec.into_vec() method:

use bool_vec::boolvec;

let bv = boolvec![true, false, true];

let vector = vec![true, false, true];

assert_eq!(bv.into_vec(), vector);

WARNING: It's recommended to try and work with BoolVec when possible. Converting to Vec<bool> might drastically increase your memory usage

Iteration

You can iterate using a for loop or convert your BoolVec into a BoolVecIter directly using BoolVec.into_iter():

use bool_vec::boolvec;

let bv = boolvec![true; 3];

for boolean in &bv {
    assert_eq!(boolean, true);
}

let mut bv_iter = bv.into_iter();

while let Some(boolean) = bv_iter.next() {
    assert_eq!(boolean, true);
}

Printing

You can either debug print and pretty print your BoolVec:

use bool_vec::boolvec;

let bv = boolvec![true; 3];

println!("{bv:?}");

println!("{bv:#?}"); // This will print up to 8 booleans in a single line

Or print the underlying bytes of your BoolVec:

use bool_vec::boolvec;

let mut bv = boolvec![true; 9];
bv.set(2, false).unwrap();

assert_eq!(format!("{bv:b}"), "[11011111, 10000000]")

It's ok if you don't understand this le latter, it's mostly for debug purposes and you don't need to concern with it.

Other

Other methods you might already know from Vec are implemented, such as:

  • BoolVec.len() to get the current length of the BoolVec;
  • BoolVec.capacity() to get the capacity;
  • BoolVec.is_empty() to check whether the BoolVec is empty or not;

Dependencies

~2.2–3MB
~54K SLoC