Function repeat_to_buffer

datafusion/functions/src/string/repeat.rs:273–286

(buffer: &mut Vec<u8>, string: &str, count: usize)

    // count must be > 0
    #[inline]
    fn repeat_to_buffer(buffer: &mut Vec<u8>, string: &str, count: usize) {
        buffer.clear();
        if !string.is_empty() {
            let src = string.as_bytes();
            // Initial copy
            buffer.extend_from_slice(src);
            // Doubling strategy: copy what we have so far until we reach the target
            while buffer.len() < src.len() * count {
                let copy_len = buffer.len().min(src.len() * count - buffer.len());
                // SAFETY: we're copying valid UTF-8 bytes that we already verified
                buffer.extend_from_within(..copy_len);
            }
        }
    }

    // Output is null IFF either input is null
    let nulls = NullBuffer::union(string_array.nulls(), number_array.nulls());