fn poll_next()

in src/columnar_storage/src/read.rs [349:384]
36 lines of code
4 McCabe index (conditional complexity)

    fn poll_next(
        mut self: Pin<&mut Self>,
        ctx: &mut std::task::Context,
    ) -> Poll<Option<Self::Item>> {
        loop {
            match self.stream.poll_next_unpin(ctx) {
                Poll::Pending => return Poll::Pending,
                Poll::Ready(None) => {
                    let value = if let Some(mut pending) = self.pending_batch.take() {
                        self.maybe_remove_builtin_columns(&mut pending);
                        let res = self
                            .value_operator
                            .merge(pending)
                            .map_err(|e| DataFusionError::External(Box::new(e)));
                        Some(res)
                    } else {
                        None
                    };
                    return Poll::Ready(value);
                }
                Poll::Ready(Some(v)) => match v {
                    Ok(v) => match self.merge_batch(v) {
                        Ok(v) => {
                            if let Some(v) = v {
                                return Poll::Ready(Some(Ok(v)));
                            }
                        }
                        Err(e) => {
                            return Poll::Ready(Some(Err(DataFusionError::External(Box::new(e)))))
                        }
                    },
                    Err(e) => return Poll::Ready(Some(Err(e))),
                },
            }
        }
    }