Function zip_impl

arrow-select/src/zip.rs:148–201

(
    mask: &BooleanArray,
    truthy: &ArrayData,
    truthy_is_scalar: bool,
    falsy: &ArrayData,
    falsy_is_scalar: bool,
)

}

fn zip_impl(
    mask: &BooleanArray,
    truthy: &ArrayData,
    truthy_is_scalar: bool,
    falsy: &ArrayData,
    falsy_is_scalar: bool,
) -> Result<ArrayRef, ArrowError> {
    let mut mutable = MutableArrayData::new(vec![truthy, falsy], false, truthy.len());

    // the SlicesIterator slices only the true values. So the gaps left by this iterator we need to
    // fill with falsy values

    // keep track of how much is filled
    let mut filled = 0;

    let mask_buffer = maybe_prep_null_mask_filter(mask);
    SlicesIterator::from(&mask_buffer).for_each(|(start, end)| {
        // the gap needs to be filled with falsy values
        if start > filled {
            if falsy_is_scalar {
                for _ in filled..start {
                    // Copy the first item from the 'falsy' array into the output buffer.
                    mutable.extend(1, 0, 1);
                }
            } else {
                mutable.extend(1, filled, start);
            }
        }
        // fill with truthy values
        if truthy_is_scalar {
            for _ in start..end {
                // Copy the first item from the 'truthy' array into the output buffer.
                mutable.extend(0, 0, 1);
            }
        } else {
            mutable.extend(0, start, end);
        }
        filled = end;
    });
    // the remaining part is falsy
    if filled < mask.len() {
        if falsy_is_scalar {
            for _ in filled..mask.len() {
                // Copy the first item from the 'falsy' array into the output buffer.
                mutable.extend(1, 0, 1);
            }
        } else {
            mutable.extend(1, filled, mask.len());
        }
    }

    let data = mutable.freeze();
    Ok(make_array(data))
}

/// Zipper for 2 scalars
///