Function take_need

datafusion/functions-aggregate/src/first_last/state.rs:293–309

(
    bool_buf_builder: &mut BooleanBufferBuilder,
    emit_to: EmitTo,
)

}

pub(crate) fn take_need(
    bool_buf_builder: &mut BooleanBufferBuilder,
    emit_to: EmitTo,
) -> BooleanBuffer {
    let bool_buf = bool_buf_builder.finish();
    match emit_to {
        EmitTo::All => bool_buf,
        EmitTo::First(n) => {
            // split off the first N values in seen_values
            //
            let first_n: BooleanBuffer = bool_buf.slice(0, n);
            // reset the existing buffer
            bool_buf_builder.append_buffer(&bool_buf.slice(n, bool_buf.len() - n));
            first_n
        }
    }
}

#[cfg(test)]
mod tests {