Function concat_structs

arrow-select/src/concat.rs:304–343

(arrays: &[&dyn Array], fields: &Fields)

}

fn concat_structs(arrays: &[&dyn Array], fields: &Fields) -> Result<ArrayRef, ArrowError> {
    let mut len = 0;
    let mut has_nulls = false;
    let structs = arrays
        .iter()
        .map(|a| {
            len += a.len();
            has_nulls |= a.null_count() > 0;
            a.as_struct()
        })
        .collect::<Vec<_>>();

    let nulls = has_nulls.then(|| {
        let mut b = BooleanBufferBuilder::new(len);
        for s in &structs {
            match s.nulls() {
                Some(n) => b.append_buffer(n.inner()),
                None => b.append_n(s.len(), true),
            }
        }
        NullBuffer::new(b.finish())
    });

    let column_concat_result = (0..fields.len())
        .map(|i| {
            let extracted_cols = structs
                .iter()
                .map(|s| s.column(i).as_ref())
                .collect::<Vec<_>>();
            concat(&extracted_cols)
        })
        .collect::<Result<Vec<_>, ArrowError>>()?;

    Ok(Arc::new(StructArray::try_new_with_length(
        fields.clone(),
        column_concat_result,
        nulls,
        len,
    )?))
}

/// Concatenate multiple RunArray instances into a single RunArray.
///