Function read_value

nodedb-query/src/msgpack_scan/reader.rs:378–424

Read a scalar msgpack value at `offset` into `nodedb_types::Value`. Handles null, bool, integers, floats, and strings. For complex types (array, map, bin, ext), returns `None` — caller should use `json_from_msgpack` for those.

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

/// (array, map, bin, ext), returns `None` — caller should use
/// `json_from_msgpack` for those.
pub fn read_value(buf: &[u8], offset: usize) -> Option<nodedb_types::Value> {
    let tag = get(buf, offset)?;
    match tag {
        NIL => Some(nodedb_types::Value::Null),
        TRUE => Some(nodedb_types::Value::Bool(true)),
        FALSE => Some(nodedb_types::Value::Bool(false)),
        // Integers
        0x00..=0x7f => Some(nodedb_types::Value::Integer(tag as i64)),
        0xe0..=0xff => Some(nodedb_types::Value::Integer((tag as i8) as i64)),
        UINT8 => Some(nodedb_types::Value::Integer(get(buf, offset + 1)? as i64)),
        UINT16 => Some(nodedb_types::Value::Integer(
            read_u16_be(buf, offset + 1)? as i64
        )),
        UINT32 => Some(nodedb_types::Value::Integer(
            read_u32_be(buf, offset + 1)? as i64
        )),
        UINT64 => Some(nodedb_types::Value::Integer(
            read_u64_be(buf, offset + 1)? as i64
        )),
        INT8 => Some(nodedb_types::Value::Integer(
            get(buf, offset + 1)? as i8 as i64
        )),
        INT16 => Some(nodedb_types::Value::Integer(
            read_u16_be(buf, offset + 1)? as i16 as i64,
        )),
        INT32 => Some(nodedb_types::Value::Integer(
            read_u32_be(buf, offset + 1)? as i32 as i64,
        )),
        INT64 => Some(nodedb_types::Value::Integer(
            read_u64_be(buf, offset + 1)? as i64
        )),
        // Floats
        FLOAT32 => {
            let bits = read_u32_be(buf, offset + 1)?;
            Some(nodedb_types::Value::Float(f32::from_bits(bits) as f64))
        }
        FLOAT64 => {
            let bits = read_u64_be(buf, offset + 1)?;
            Some(nodedb_types::Value::Float(f64::from_bits(bits)))
        }
        // Strings
        0xa0..=0xbf | STR8 | STR16 | STR32 => {
            read_str(buf, offset).map(|s| nodedb_types::Value::String(s.to_string()))
        }
        _ => None,
    }
}

/// 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.