Function map_strings

datafusion/functions/src/unicode/substrindex.rs:477–499

(
    string_array: S,
    mut builder: GenericStringArrayBuilder<O>,
    f: F,
)

}

fn map_strings<'a, S, O, F>(
    string_array: S,
    mut builder: GenericStringArrayBuilder<O>,
    f: F,
) -> Result<ArrayRef>
where
    S: StringArrayType<'a> + Copy,
    O: OffsetSizeTrait,
    F: Fn(&'a str) -> &'a str,
{
    let nulls = string_array.nulls().cloned();
    for i in 0..string_array.len() {
        if nulls.as_ref().is_some_and(|n| n.is_null(i)) {
            builder.append_placeholder();
            continue;
        }
        // SAFETY: `i < string_array.len()` and `nulls` is valid at i, so the
        // input is also valid at i.
        let s = unsafe { string_array.value_unchecked(i) };
        builder.append_value(f(s));
    }
    Ok(Arc::new(builder.finish(nulls)?) as ArrayRef)
}

#[inline]
fn substr_index_slice<'a>(string: &'a str, delimiter: &str, count: i64) -> &'a str {