moqtap-codec 0.5.0

//! Draft-16 specific types.

/// Object status values, from MoQ Transport draft-16 Section 10.2.1.1
/// "Object Status".
///
/// Draft-16 is where the status set narrows to three: it assigns 0x0, 0x3 and
/// 0x4 only. Object Does Not Exist (0x1), assigned by every draft from 07
/// through 15, is gone — draft-16 rewrites the section around a publisher
/// "explicitly communicate that a specific range of objects does not exist" and
/// drops the per-object form. Of every other value the section says: "Any other
/// value SHOULD be treated as a protocol error and the session SHOULD be closed
/// with a PROTOCOL_VIOLATION". [`ObjectStatus::from_u64`] answers `None` for
/// 0x1, for 0x2, and for everything else the draft leaves unassigned.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u64)]
pub enum ObjectStatus {
    /// Normal object. Implicit for any non-zero length object; zero-length
    /// objects encode it explicitly.
    Normal = 0x00,
    /// End of Group. Object ID is one greater than the largest object produced
    /// in the group identified by the Group ID; 0 means the group is empty.
    EndOfGroup = 0x03,
    /// End of Track. Either Group ID is the largest group produced in the track
    /// and Object ID is one greater than the largest object in that group, or
    /// Group ID is one greater than the largest group produced and Object ID is
    /// zero.
    EndOfTrack = 0x04,
}

impl ObjectStatus {
    /// Every status draft-16 assigns, in ascending wire order.
    ///
    /// This is exactly the set [`ObjectStatus::from_u64`] accepts. Any other
    /// value is one the draft does not assign.
    pub const ALL: &[ObjectStatus] =
        &[ObjectStatus::Normal, ObjectStatus::EndOfGroup, ObjectStatus::EndOfTrack];

    /// Convert a raw u64 to an `ObjectStatus`, or `None` if draft-16 does not
    /// assign that value.
    pub fn from_u64(v: u64) -> Option<Self> {
        match v {
            0x00 => Some(ObjectStatus::Normal),
            0x03 => Some(ObjectStatus::EndOfGroup),
            0x04 => Some(ObjectStatus::EndOfTrack),
            _ => None,
        }
    }

    /// Return the wire value.
    pub fn as_u64(self) -> u64 {
        self as u64
    }
}