Function map_header

nodedb-query/src/msgpack_scan/reader.rs:428–436

Return the number of key-value pairs and the offset of the first pair, for the map starting at `offset`. Returns `None` if not a map.

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

/// Return the number of key-value pairs and the offset of the first pair,
/// for the map starting at `offset`. Returns `None` if not a map.
pub fn map_header(buf: &[u8], offset: usize) -> Option<(usize, usize)> {
    let tag = get(buf, offset)?;
    match tag {
        0x80..=0x8f => Some(((tag & 0x0f) as usize, offset + 1)),
        MAP16 => Some((read_u16_be(buf, offset + 1)? as usize, offset + 3)),
        MAP32 => Some((read_u32_be(buf, offset + 1)? as usize, offset + 5)),
        _ => None,
    }
}

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