1 files changed, 17 insertions, 13 deletions

diff --git a/crates/ra_syntax/src/token_set.rs b/crates/ra_syntax/src/token_set.rs
index d407dfa48..b3fe633e0 100644
--- a/crates/ra_syntax/src/token_set.rs
+++ b/crates/ra_syntax/src/token_set.rs
@@ -1,30 +1,34 @@
 use crate::SyntaxKind;
 
 #[derive(Clone, Copy)]
-pub(crate) struct TokenSet(pub(crate) u128);
-
-fn mask(kind: SyntaxKind) -> u128 {
-    1u128 << (kind as usize)
-}
+pub(crate) struct TokenSet(u128);
 
 impl TokenSet {
-    pub const EMPTY: TokenSet = TokenSet(0);
+    pub const fn empty() -> TokenSet {
+        TokenSet(0)
+    }
+
+    pub const fn singleton(kind: SyntaxKind) -> TokenSet {
+        TokenSet(mask(kind))
+    }
+
+    pub const fn union(self, other: TokenSet) -> TokenSet {
+        TokenSet(self.0 | other.0)
+    }
 
     pub fn contains(&self, kind: SyntaxKind) -> bool {
         self.0 & mask(kind) != 0
     }
 }
 
-#[macro_export]
-macro_rules! token_set {
-    ($($t:ident),*) => { TokenSet($(1u128 << ($t as usize))|*) };
-    ($($t:ident),* ,) => { token_set!($($t),*) };
+const fn mask(kind: SyntaxKind) -> u128 {
+    1u128 << (kind as usize)
 }
 
 #[macro_export]
-macro_rules! token_set_union {
-    ($($ts:expr),*) => { TokenSet($($ts.0)|*) };
-    ($($ts:expr),* ,) => { token_set_union!($($ts),*) };
+macro_rules! token_set {
+    ($($t:ident),*) => { TokenSet::empty()$(.union(TokenSet::singleton($t)))* };
+    ($($t:ident),* ,) => { token_set!($($t),*) };
 }
 
 #[test]