Method apply_active_mapping

prqlc/prqlc/src/sql/pq/positional_mapping.rs:29–47

Reorder or remove columns to make `Union` happy.

(&mut self, output: Vec<CId>)

    /// Reorder or remove columns to make `Union` happy.
    pub(crate) fn apply_active_mapping(&mut self, output: Vec<CId>) -> Vec<CId> {
        if let Some(mapping) = &self.active_positional_mapping {
            // Check if the mapping indices are valid for the output
            if mapping.iter().any(|idx| *idx >= output.len()) {
                log::warn!(
                    "positional mapping indices out of bounds: mapping={mapping:?}, output_len={}",
                    output.len()
                );
                // If mapping is invalid, don't apply it
                return output;
            }

            let new_output = mapping.iter().map(|idx| output[*idx]).collect();
            log::debug!("remapping {output:?} to {new_output:?} via {mapping:?}");
            new_output
        } else {
            output
        }
    }

    pub fn compute_and_store_mapping(&mut self, before: &[CId], after: &[CId], riid: &RIId) {
        let mapping: Vec<_> = after