internal: simplify TokenSet implementation

Author: davidsemakula

crates/parser/src/token_set.rs

@@ -6,6 +6,9 @@ use crate::SyntaxKind;
 #[derive(Clone,Copy)]
 pub(crate)structTokenSet([u64;3]);
 
+/// `TokenSet`s should only include token `SyntaxKind`s, so the discriminant of any passed/included
+/// `SyntaxKind` must *not* be greater than that of the last token `SyntaxKind`.
+/// See #17037.
 constLAST_TOKEN_KIND_DISCRIMINANT:usize = SyntaxKind::SHEBANGasusize;
 
 implTokenSet{
@@ -15,13 +18,13 @@ impl TokenSet {
 letmut res = [0;3];
 letmut i = 0;
 while i < kinds.len(){
-letkind = kinds[i];
+letdiscriminant = kinds[i]asusize;
 debug_assert!(
-kind asusize <= LAST_TOKEN_KIND_DISCRIMINANT,
+discriminant <= LAST_TOKEN_KIND_DISCRIMINANT,
 "Expected a token `SyntaxKind`"
 );
-let idx = kind asusize / 64;
- res[idx] |= mask(kind);
+let idx = discriminant / 64;
+ res[idx] |= 1 << (discriminant % 64);
  i += 1;
 }
 TokenSet(res)
@@ -32,20 +35,17 @@ impl TokenSet {
 }
 
 pub(crate)constfncontains(&self,kind:SyntaxKind) -> bool{
+let discriminant = kind asusize;
 debug_assert!(
-kind asusize <= LAST_TOKEN_KIND_DISCRIMINANT,
+discriminant <= LAST_TOKEN_KIND_DISCRIMINANT,
 "Expected a token `SyntaxKind`"
 );
-let idx = kind asusize / 64;
-self.0[idx]&mask(kind) != 0
+let idx = discriminant / 64;
+let mask = 1 << (discriminant % 64);
+self.0[idx]& mask != 0
 }
 }
 
-constfnmask(kind:SyntaxKind) -> u64{
-debug_assert!(kind asusize <= LAST_TOKEN_KIND_DISCRIMINANT,"Expected a token `SyntaxKind`");
-1 << (kind asusize % 64)
-}
-
 #[test]
 fntoken_set_works_for_tokens(){
 usecrate::SyntaxKind::*;