Enum MatcherTier 

#[non_exhaustive]
pub enum MatcherTier {
    Byte,
    Literal,
    LiteralSet,
    Regex,
}

Available on crate feature strmatch only.

Which engine class a StrMatcher is dispatching to. Tiers are ordered by cost – Byte > Literal > LiteralSet > Regex (higher means faster). Use Self::rank for min_tier comparisons.

Budgets below are typical for a modern x86 server on a ~200-byte haystack. Hardware-dependent; cold caches and pathological inputs move them around.

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.

Byte

≤ 30 ns – direct byte ops: memchr / memchr2/3 / single-byte starts_with / ends_with / ==.

Literal

≤ 200 ns – single multi-byte literal: memmem::Finder / multi-byte starts_with / ends_with / ==.

LiteralSet

≤ 500 ns – aho-corasick over ≥ 2 literals (optional uniform anchor checked after the AC scan).

Regex

Bounded by the regex engine – regex-automata::meta::Regex fall-through. Cost depends on pattern and haystack.

Implementations

impl MatcherTier

pub const fn rank(self) -> u8

Cost rank – higher means faster. Useful for min_tier comparisons without depending on the specific ns numbers.

Ordering: Byte (4) > Literal (3) > LiteralSet (2) > Regex (1).

pub const fn typical_budget_ns(self) -> Option<u64>

Indicative ns budget per is_match call on a ~200-byte haystack (modern x86 server). None for Self::Regex since the engine is unbounded.

Numbers are estimates from benchmarks in benches/strmatch.rs; real-world cost varies with haystack length, cache state, and pattern complexity.

Trait Implementations

impl Clone for MatcherTier

fn clone(&self) -> MatcherTier

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Copy for MatcherTier

impl Debug for MatcherTier

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

Formats the value using the given formatter.

impl Display for MatcherTier

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

Formats the value using the given formatter.

impl Eq for MatcherTier

impl Hash for MatcherTier

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 MatcherTier

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

Tests for self and other values to be equal, and is used by ==.

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

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl StructuralPartialEq for MatcherTier