Struct SubgroupHeader 

pub struct SubgroupHeader {
    pub header_type: u8,
    pub track_alias: VarInt,
    pub group_id: VarInt,
    pub subgroup_id: VarInt,
    pub publisher_priority: Option<u8>,
}

Fields

header_type: u8

track_alias: VarInt

group_id: VarInt

subgroup_id: VarInt

publisher_priority: Option<u8>

Implementations

impl SubgroupHeader

pub fn decode(buf: &mut impl Buf) -> Result<Self, CodecError>

Decode a subgroup header, Type Flags field included.

The field is read as a whole varint of whatever width the sender used, and the value it decodes to is what the three Section 11.4.2 conditions are applied to. A non-minimal spelling of a valid value is accepted: 0x8010 decodes to 16, which is a legal Type Flags, and this reads it. See the module documentation for why the draft leaves that open and why permissive-on-receive is the choice here; the encoder is the strict half and always writes the one-byte form.

Draft-19 refused every wide spelling before looking at the value, which is the behaviour this replaces. Reading the whole field is also what lets stream_type_error tell a padding or SETUP stream — both assigned, both several bytes wide — from a Type Table 3 does not assign.

pub fn encode(&self, buf: &mut impl BufMut)

Serialize the header exactly as its Type byte describes it.

Infallible, and so willing to write a Type draft-20 Section 11.4.2 tells an endpoint to reject — including a reserved-mode Type this module’s own Self::decode refuses to read back. Prefer Self::encode_checked, which refuses those Types instead.

pub fn encode_checked(&self, buf: &mut impl BufMut) -> Result<(), CodecError>

Serialize the header, refusing a Type value draft-20 forbids.

Errors with CodecError::InvalidField for exactly the Types draft-20 Section 11.4.2 lists as invalid (the same set Self::decode refuses), before any byte is written, so a refused header leaves buf untouched. Everything else is written by Self::encode.

The check belongs on the encode side as well as the decode side because the two halves would otherwise disagree about which streams exist: a reserved-mode header written by Self::encode cannot be read back by Self::decode, and a codec used to rewrite captured traffic would emit a stream it could not then parse.

pub fn has_properties(&self) -> bool

pub fn subgroup_id_mode(&self) -> u8

The subgroup-ID mode: (header_type & 0x06) >> 1.

0 = no subgroup ID on the wire and it is zero; 1 = the subgroup ID is the first object’s ID; 2 = an explicit ID follows the Group ID; 3 = reserved. Exposed because the mask is module-private and dispatch::AnySubgroupHeader::subgroup_id_mode cannot read it.

3 never comes back from Self::decode, which refuses the Types carrying it. header_type is a public field, so a hand-built header can still report it; Self::encode_checked is what refuses to put one on the wire.

pub fn is_end_of_group(&self) -> bool

pub fn is_first_object(&self) -> bool

true when the FIRST_OBJECT bit (0x40) is set, signaling the first object on this stream is the original publisher’s first object in the subgroup. Added in draft-18.

Trait Implementations

impl Clone for SubgroupHeader

fn clone(&self) -> SubgroupHeader

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for SubgroupHeader

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.