Enum MatcherField 

#[non_exhaustive]
pub enum MatcherField {
    TrackAlias,
    SubgroupId,
    Priority,
}

One Matcher key, named so a report about it is typed rather than a string.

Only the keys that can be unmatchable are here, and that is the whole point of the type: it is carried by ImpairmentKind::ShapeRuleUnmatchable, which fires when a rule keys on something this draft and stream kind cannot carry. The other four keys — side, group_id, object_id and every_nth — are present on every framed unit by construction, so a rule keyed on one of them that fails to match failed on its value, which is the rule working, not a rule that cannot work.

#[non_exhaustive] with no Default: a later draft that makes another key optional adds a variant, and no key is a meaningful zero.

Variants (Non-exhaustive)

Non-exhaustive enums could have additional variants added in future. Therefore, when matching against variants of non-exhaustive enums, an extra wildcard arm must be added to account for any future variants.

TrackAlias

Matcher::track_alias, against a unit whose stream carried none — every fetch stream.

SubgroupId

Matcher::subgroup_id, against a unit whose header carried none — eight drafts in first-object mode, and 17-19 in reserved mode 3.

Never reported about a datagram, which carries no subgroup ID on any draft. That is not a fact about one header, so it is a pre-run refusal — Capabilities::admit_class — rather than something a run discovers. See Matcher::unmatchable_fields_datagram.

Priority

Matcher::priority, against a unit whose header set the default-priority bit — drafts 15-19, on a subgroup object and on a datagram alike.

Implementations

impl MatcherField

pub(crate) const fn bit(self) -> u8

This field’s bit in a per-class report-once mask.

A four-variant enum fits one byte, so the “reported already” state for a whole class is one AtomicU8 and the check is one relaxed fetch_or — taken only when a field is actually absent, so a profile whose keys are all carried never touches it.

Trait Implementations

impl Clone for MatcherField

fn clone(&self) -> MatcherField

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for MatcherField

impl Debug for MatcherField

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

Formats the value using the given formatter.

impl Eq for MatcherField

impl Hash for MatcherField

fn hash<__H: Hasher>(&self, state: &mut __H)

Feeds this value into the given Hasher.

fn hash_slice<H>(data: &[Self], state: &mut H)

where H: Hasher, Self: Sized,

Feeds a slice of this type into the given Hasher.

impl PartialEq for MatcherField

fn eq(&self, other: &MatcherField) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl StructuralPartialEq for MatcherField