Merge #7513

7513: NFA parser for mbe matcher r=matklad a=edwin0cheng

Almost straight porting from rustc one, but a little bit slow :(

```
rust-analyzer analysis-stats -q . 
```

From:
```log
Database loaded:     636.11ms, 277minstr
  crates: 36, mods: 594, decls: 11527, fns: 9017
Item Collection:     10.99s, 60ginstr
  exprs: 249618, ??ty: 2699 (1%), ?ty: 2101 (0%), !ty: 932
Inference:           28.94s, 123ginstr
Total:               39.93s, 184ginstr
```

To:
```log
Database loaded:     630.90ms, 277minstr
  crates: 36, mods: 594, decls: 11528, fns: 9018
Item Collection:     13.70s, 77ginstr
  exprs: 249482, ??ty: 2699 (1%), ?ty: 2101 (0%), !ty: 932
Inference:           30.27s, 133ginstr
Total:               43.97s, 211ginstr
```

Fixes #4777

Co-authored-by: Edwin Cheng <[email protected]>

1 files changed, 1 insertions, 10 deletions

diff --git a/crates/mbe/src/lib.rs b/crates/mbe/src/lib.rs
index 4c298f85f..f3d2da55a 100644
--- a/crates/mbe/src/lib.rs
+++ b/crates/mbe/src/lib.rs
@@ -21,7 +21,7 @@ use test_utils::mark;
 pub use tt::{Delimiter, DelimiterKind, Punct};
 
 use crate::{
-    parser::{parse_pattern, parse_template, Op},
+    parser::{parse_pattern, parse_template, MetaTemplate, Op},
     tt_iter::TtIter,
 };
 
@@ -94,15 +94,6 @@ struct Rule {
     rhs: MetaTemplate,
 }
 
-#[derive(Clone, Debug, PartialEq, Eq)]
-struct MetaTemplate(Vec<Op>);
-
-impl<'a> MetaTemplate {
-    fn iter(&self) -> impl Iterator<Item = &Op> {
-        self.0.iter()
-    }
-}
-
 #[derive(Clone, Copy, Debug, PartialEq, Eq)]
 struct Shift(u32);