Struct FetchObjectReader 

pub struct FetchObjectReader { /* private fields */ }

Stateful resolver for the Objects on one draft-16 fetch stream.

Draft-16 Section 10.4.4.1 lets an Object leave its Group ID, Subgroup ID, Object ID or Priority off the wire and take the value from the Object before it, so the fields of a fetch object are only meaningful in stream order. This carries that running state; FetchObjectHeader carries only what the bytes said.

Unlike a subgroup stream, nothing here is a delta: a field that is on the wire replaces the running value outright, and a field that is absent either repeats it or steps it by one, as Table 5 and Table 6 say.

Implementations

impl FetchObjectReader

pub fn new() -> Self

A reader positioned before the first Object of a fetch stream, with no prior Object to inherit from.

pub fn resolve( &mut self, header: &FetchObjectHeader, ) -> Result<FetchObjectLocation, CodecError>

Resolve one Object’s Location against the Object before it, advancing the running state.

Errors with CodecError::InvalidField when the first Object of the stream leaves out a Group ID or an Object ID, or names the prior Object’s Subgroup ID: draft-16 Section 10.4.4.1 makes a first Object that “uses a flag that references fields in the prior Object” a PROTOCOL_VIOLATION, and for these three fields there is no value to produce even if it were not. An absent Priority is the same violation by the draft’s letter and is reported by FetchObjectHeader::references_prior_object, but it is resolvable — the Location simply carries no priority — so it is not refused here.

Errors with CodecError::InvalidField when a Subgroup ID one greater than the prior Object’s would not fit a varint.

A FetchEndOfRange marker takes part in the running state like any other Object: Section 10.4.4.2 gives it a Location, and it is a “serialized Object” in the same section’s words, so the Object after it inherits its Group ID and steps from its Object ID.

Trait Implementations

impl Clone for FetchObjectReader

fn clone(&self) -> FetchObjectReader

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FetchObjectReader

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

Formats the value using the given formatter.

impl Default for FetchObjectReader

fn default() -> FetchObjectReader

Returns the “default value” for a type.