fn compare_greater_byte_array_decimals()

in parquet/src/column/writer/mod.rs [1140:1185]

• 30 lines of code
• 11 McCabe index (conditional complexity)

fn compare_greater_byte_array_decimals(a: &[u8], b: &[u8]) -> bool {
    let a_length = a.len();
    let b_length = b.len();

    if a_length == 0 || b_length == 0 {
        return a_length > 0;
    }

    let first_a: u8 = a[0];
    let first_b: u8 = b[0];

    // We can short circuit for different signed numbers or
    // for equal length bytes arrays that have different first bytes.
    // The equality requirement is necessary for sign extension cases.
    // 0xFF10 should be equal to 0x10 (due to big endian sign extension).
    if (0x80 & first_a) != (0x80 & first_b)
        || (a_length == b_length && first_a != first_b)
    {
        return (first_a as i8) > (first_b as i8);
    }

    // When the lengths are unequal and the numbers are of the same
    // sign we need to do comparison by sign extending the shorter
    // value first, and once we get to equal sized arrays, lexicographical
    // unsigned comparison of everything but the first byte is sufficient.

    let extension: u8 = if (first_a as i8) < 0 { 0xFF } else { 0 };

    if a_length != b_length {
        let not_equal = if a_length > b_length {
            let lead_length = a_length - b_length;
            a[0..lead_length].iter().any(|&x| x != extension)
        } else {
            let lead_length = b_length - a_length;
            b[0..lead_length].iter().any(|&x| x != extension)
        };

        if not_equal {
            let negative_values: bool = (first_a as i8) < 0;
            let a_longer: bool = a_length > b_length;
            return if negative_values { !a_longer } else { a_longer };
        }
    }

    (a[1..]) > (b[1..])
}