Function array_header

nodedb-query/src/msgpack_scan/reader.rs:440–448

Return the number of elements and the offset of the first element, for the array starting at `offset`. Returns `None` if not an array.

(buf: &[u8], offset: usize)

/// Return the number of elements and the offset of the first element,
/// for the array starting at `offset`. Returns `None` if not an array.
pub fn array_header(buf: &[u8], offset: usize) -> Option<(usize, usize)> {
    let tag = get(buf, offset)?;
    match tag {
        0x90..=0x9f => Some(((tag & 0x0f) as usize, offset + 1)),
        ARRAY16 => Some((read_u16_be(buf, offset + 1)? as usize, offset + 3)),
        ARRAY32 => Some((read_u32_be(buf, offset + 1)? as usize, offset + 5)),
        _ => None,
    }
}

#[cfg(test)]
mod tests {