fn hash_elements>()

in crypto/src/hash/rescue/rp64_256/mod.rs [212:245]
18 lines of code
4 McCabe index (conditional complexity)

    fn hash_elements<E: FieldElement<BaseField = Self::BaseField>>(elements: &[E]) -> Self::Digest {
        // convert the elements into a list of base field elements
        let elements = E::as_base_elements(elements);

        // initialize state to all zeros, except for the last element of the capacity part, which
        // is set to the number of elements to be hashed. this is done so that adding zero elements
        // at the end of the list always results in a different hash.
        let mut state = [BaseElement::ZERO; STATE_WIDTH];
        state[CAPACITY_RANGE.start] = BaseElement::new(elements.len() as u64);

        // absorb elements into the state one by one until the rate portion of the state is filled
        // up; then apply the Rescue permutation and start absorbing again; repeat until all
        // elements have been absorbed
        let mut i = 0;
        for &element in elements.iter() {
            state[RATE_RANGE.start + i] += element;
            i += 1;
            if i % RATE_WIDTH == 0 {
                Self::apply_permutation(&mut state);
                i = 0;
            }
        }

        // if we absorbed some elements but didn't apply a permutation to them (would happen when
        // the number of elements is not a multiple of RATE_WIDTH), apply the Rescue permutation.
        // we don't need to apply any extra padding because we injected total number of elements
        // in the input list into the capacity portion of the state during initialization.
        if i > 0 {
            Self::apply_permutation(&mut state);
        }

        // return the first 4 elements of the state as hash result
        ElementDigest::new(state[DIGEST_RANGE].try_into().unwrap())
    }