Function unhex_common

datafusion/spark/src/function/math/unhex.rs:84–110

Decodes a hex-encoded byte slice into binary data. Returns `true` if decoding succeeded, `false` if the input contains invalid hex characters.

(bytes: &[u8], out: &mut Vec<u8>)

/// Decodes a hex-encoded byte slice into binary data.
/// Returns `true` if decoding succeeded, `false` if the input contains invalid hex characters.
fn unhex_common(bytes: &[u8], out: &mut Vec<u8>) -> bool {
    if bytes.is_empty() {
        return true;
    }

    let mut i = 0usize;

    // If the hex string length is odd, implicitly left-pad with '0'.
    if (bytes.len() & 1) == 1 {
        match hex_nibble(bytes[0]) {
            // Equivalent to (0 << 4) | lo
            Some(lo) => out.push(lo),
            None => return false,
        }
        i = 1;
    }

    while i + 1 < bytes.len() {
        match (hex_nibble(bytes[i]), hex_nibble(bytes[i + 1])) {
            (Some(hi), Some(lo)) => out.push((hi << 4) | lo),
            _ => return false,
        }
        i += 2;
    }

    true
}

/// Converts an iterator of hex strings to a binary array.
fn unhex_array<I, T>(