Struct rustc_expand::mbe::macro_parser::MatcherPos

struct MatcherPos {
    idx: usize,
    matches: Lrc<Vec<NamedMatch>>,
}

A single matcher position, representing the state of matching.

Fields

idx: usize

The index into TtParser::locs, which represents the “dot”.

matches: Lrc<Vec<NamedMatch>>

The matches made against metavar decls so far. On a successful match, this vector ends up with one element per metavar decl in the matcher. Each element records token trees matched against the relevant metavar by the black box parser. An element will be a MatchedSeq if the corresponding metavar decl is within a sequence.

It is critical to performance that this is an Lrc, because it gets cloned frequently when processing sequences. Mostly for sequence-ending possibilities that must be tried but end up failing.

Implementations

impl MatcherPos

fn push_match(&mut self, metavar_idx: usize, seq_depth: usize, m: NamedMatch)

Adds m as a named match for the metavar_idx-th metavar. There are only two call sites, and both are hot enough to be always worth inlining.

Layout

Note: Most layout information is completely unstable and may even differ between compilations. The only exception is types with certain repr(...) attributes. Please see the Rust Reference’s “Type Layout” chapter for details on type layout guarantees.

Size: 16 bytes