fn shrink_vec()

in lain/src/mutatable.rs [130:164]

• 29 lines of code
• 4 McCabe index (conditional complexity)

fn shrink_vec<T, R: Rng>(vec: &mut Vec<T>, mutator: &mut Mutator<R>) {
    if vec.is_empty() {
        return;
    }

    let resize_count = VecResizeCount::new_fuzzed(mutator, None);
    let mut num_elements = match resize_count {
        VecResizeCount::Quarter => vec.len() / 4,
        VecResizeCount::Half => vec.len() / 2,
        VecResizeCount::ThreeQuarters => vec.len() - (vec.len() / 4),
        VecResizeCount::FixedBytes => mutator.gen_range(1, 9),
        VecResizeCount::AllBytes => vec.len(),
    };

    if num_elements == 0 {
        num_elements = mutator.gen_range(0, vec.len() + 1);
    }

    num_elements = std::cmp::min(num_elements, vec.len());

    // Special case probably isn't required here, but better to be explicit
    if num_elements == vec.len() {
        vec.drain(..);
        return;
    }

    match VecResizeDirection::new_fuzzed(mutator, None) {
        VecResizeDirection::FromBeginning => {
            vec.drain(0..num_elements);
        }
        VecResizeDirection::FromEnd => {
            vec.drain(vec.len() - num_elements..);
        }
    }
}