Parse exclusive range pattern

Author: lowr

crates/hir-def/src/macro_expansion_tests/mbe/matching.rs

@@ -106,7 +106,6 @@ stringify!(;
 
 #[test]
 fn range_patterns() {
-    // FIXME: rustc thinks there are three patterns here, not one.
     check(
         r#"
 macro_rules! m {
@@ -118,7 +117,7 @@ m!(.. .. ..);
 macro_rules! m {
     ($($p:pat)*) => (stringify!($($p |)*);)
 }
-stringify!(.. .. .. |);
+stringify!(.. | .. | .. |);
 "#]],
     );
 }

crates/parser/src/grammar/patterns.rs

@@ -15,6 +15,10 @@ pub(super) const PATTERN_FIRST: TokenSet =
 
 const PAT_TOP_FIRST: TokenSet = PATTERN_FIRST.union(TokenSet::new(&[T![|]]));
 
+/// Set of possible tokens at the start of a range pattern's end bound.
+const RANGE_PAT_END_FIRST: TokenSet =
+    expressions::LITERAL_FIRST.union(paths::PATH_FIRST).union(TokenSet::new(&[T![-]]));
+
 pub(crate) fn pattern(p: &mut Parser<'_>) {
     pattern_r(p, PAT_RECOVERY_SET);
 }
@@ -105,6 +109,52 @@ fn pattern_single_r(p: &mut Parser<'_>, recovery_set: TokenSet) {
         return;
     }
 
+    // test exclusive_range_pat
+    // fn main() {
+    //     match 42 {
+    //         ..0 => {}
+    //         1..2 => {}
+    //     }
+    // }
+
+    // test dot_dot_pat
+    // fn main() {
+    //     let .. = ();
+    //     //
+    //     // Tuples
+    //     //
+    //     let (a, ..) = ();
+    //     let (a, ..,) = ();
+    //     let Tuple(a, ..) = ();
+    //     let Tuple(a, ..,) = ();
+    //     let (.., ..) = ();
+    //     let Tuple(.., ..) = ();
+    //     let (.., a, ..) = ();
+    //     let Tuple(.., a, ..) = ();
+    //     //
+    //     // Slices
+    //     //
+    //     let [..] = ();
+    //     let [head, ..] = ();
+    //     let [head, tail @ ..] = ();
+    //     let [head, .., cons] = ();
+    //     let [head, mid @ .., cons] = ();
+    //     let [head, .., .., cons] = ();
+    //     let [head, .., mid, tail @ ..] = ();
+    //     let [head, .., mid, .., cons] = ();
+    // }
+    if p.at(T![..]) {
+        let m = p.start();
+        p.bump(T![..]);
+        if p.at_ts(RANGE_PAT_END_FIRST) {
+            atom_pat(p, recovery_set);
+            m.complete(p, RANGE_PAT);
+        } else {
+            m.complete(p, REST_PAT);
+        }
+        return;
+    }
+
     if let Some(lhs) = atom_pat(p, recovery_set) {
         for range_op in [T![...], T![..=], T![..]] {
             if p.at(range_op) {
@@ -173,7 +223,6 @@ fn atom_pat(p: &mut Parser<'_>, recovery_set: TokenSet) -> Option<CompletedMarke
         _ if paths::is_path_start(p) => path_or_macro_pat(p),
         _ if is_literal_pat_start(p) => literal_pat(p),
 
-        T![.] if p.at(T![..]) => rest_pat(p),
         T![_] => wildcard_pat(p),
         T![&] => ref_pat(p),
         T!['('] => tuple_pat(p),
@@ -334,39 +383,6 @@ fn wildcard_pat(p: &mut Parser<'_>) -> CompletedMarker {
     m.complete(p, WILDCARD_PAT)
 }
 
-// test dot_dot_pat
-// fn main() {
-//     let .. = ();
-//     //
-//     // Tuples
-//     //
-//     let (a, ..) = ();
-//     let (a, ..,) = ();
-//     let Tuple(a, ..) = ();
-//     let Tuple(a, ..,) = ();
-//     let (.., ..) = ();
-//     let Tuple(.., ..) = ();
-//     let (.., a, ..) = ();
-//     let Tuple(.., a, ..) = ();
-//     //
-//     // Slices
-//     //
-//     let [..] = ();
-//     let [head, ..] = ();
-//     let [head, tail @ ..] = ();
-//     let [head, .., cons] = ();
-//     let [head, mid @ .., cons] = ();
-//     let [head, .., .., cons] = ();
-//     let [head, .., mid, tail @ ..] = ();
-//     let [head, .., mid, .., cons] = ();
-// }
-fn rest_pat(p: &mut Parser<'_>) -> CompletedMarker {
-    assert!(p.at(T![..]));
-    let m = p.start();
-    p.bump(T![..]);
-    m.complete(p, REST_PAT)
-}
-
 // test ref_pat
 // fn main() {
 //     let &a = ();

crates/parser/src/tests/prefix_entries.rs

@@ -33,8 +33,7 @@ fn stmt() {
 fn pat() {
     check(PrefixEntryPoint::Pat, "x y", "x");
     check(PrefixEntryPoint::Pat, "fn f() {}", "fn");
-    // FIXME: This one is wrong, we should consume only one pattern.
-    check(PrefixEntryPoint::Pat, ".. ..", ".. ..");
+    check(PrefixEntryPoint::Pat, ".. ..", "..");
 }
 
 #[test]

crates/parser/test_data/parser/inline/ok/0207_exclusive_range_pat.rast

@@ -0,0 +1,58 @@
+SOURCE_FILE
+  FN
+    FN_KW "fn"
+    WHITESPACE " "
+    NAME
+      IDENT "main"
+    PARAM_LIST
+      L_PAREN "("
+      R_PAREN ")"
+    WHITESPACE " "
+    BLOCK_EXPR
+      STMT_LIST
+        L_CURLY "{"
+        WHITESPACE "\n    "
+        MATCH_EXPR
+          MATCH_KW "match"
+          WHITESPACE " "
+          LITERAL
+            INT_NUMBER "42"
+          WHITESPACE " "
+          MATCH_ARM_LIST
+            L_CURLY "{"
+            WHITESPACE "\n        "
+            MATCH_ARM
+              RANGE_PAT
+                DOT2 ".."
+                LITERAL_PAT
+                  LITERAL
+                    INT_NUMBER "0"
+              WHITESPACE " "
+              FAT_ARROW "=>"
+              WHITESPACE " "
+              BLOCK_EXPR
+                STMT_LIST
+                  L_CURLY "{"
+                  R_CURLY "}"
+            WHITESPACE "\n        "
+            MATCH_ARM
+              RANGE_PAT
+                LITERAL_PAT
+                  LITERAL
+                    INT_NUMBER "1"
+                DOT2 ".."
+                LITERAL_PAT
+                  LITERAL
+                    INT_NUMBER "2"
+              WHITESPACE " "
+              FAT_ARROW "=>"
+              WHITESPACE " "
+              BLOCK_EXPR
+                STMT_LIST
+                  L_CURLY "{"
+                  R_CURLY "}"
+            WHITESPACE "\n    "
+            R_CURLY "}"
+        WHITESPACE "\n"
+        R_CURLY "}"
+  WHITESPACE "\n"

crates/parser/test_data/parser/inline/ok/0207_exclusive_range_pat.rs

@@ -0,0 +1,6 @@
+fn main() {
+    match 42 {
+        ..0 => {}
+        1..2 => {}
+    }
+}