Function decode_blocks

arrow-row/src/variable.rs:221–258

Decodes a single block of data The `f` function accepts a slice of the decoded data, it may be called multiple times

(row: &[u8], options: SortOptions, mut f: impl FnMut(&[u8]))

/// Decodes a single block of data
/// The `f` function accepts a slice of the decoded data, it may be called multiple times
pub fn decode_blocks(row: &[u8], options: SortOptions, mut f: impl FnMut(&[u8])) -> usize {
    let (non_empty_sentinel, continuation) = match options.descending {
        true => (!NON_EMPTY_SENTINEL, !BLOCK_CONTINUATION),
        false => (NON_EMPTY_SENTINEL, BLOCK_CONTINUATION),
    };

    if row[0] != non_empty_sentinel {
        // Empty or null string
        return 1;
    }

    // Extracts the block length from the sentinel
    let block_len = |sentinel: u8| match options.descending {
        true => !sentinel as usize,
        false => sentinel as usize,
    };

    let mut idx = 1;
    for _ in 0..MINI_BLOCK_COUNT {
        let sentinel = row[idx + MINI_BLOCK_SIZE];
        if sentinel != continuation {
            f(&row[idx..idx + block_len(sentinel)]);
            return idx + MINI_BLOCK_SIZE + 1;
        }
        f(&row[idx..idx + MINI_BLOCK_SIZE]);
        idx += MINI_BLOCK_SIZE + 1;
    }

    loop {
        let sentinel = row[idx + BLOCK_SIZE];
        if sentinel != continuation {
            f(&row[idx..idx + block_len(sentinel)]);
            return idx + BLOCK_SIZE + 1;
        }
        f(&row[idx..idx + BLOCK_SIZE]);
        idx += BLOCK_SIZE + 1;
    }
}

/// Returns the number of bytes of encoded data
fn decoded_len(row: &[u8], options: SortOptions) -> usize {