Parse subslice patterns

cc rust-lang#1479

Author: tomjakubowski

crates/ra_parser/src/grammar/patterns.rs

@@ -36,9 +36,14 @@ pub(super) fn pattern_r(p: &mut Parser, recovery_set: TokenSet) {
         // }
         if p.at(T![...]) || p.at(T![..=]) || p.at(T![..]) {
             let m = lhs.precede(p);
+            let dots = p.current();
             p.bump();
-            atom_pat(p, recovery_set);
-            m.complete(p, RANGE_PAT);
+            if dots == T![..] && !p.at_ts(PATTERN_FIRST) {
+                m.complete(p, SUBSLICE_PAT);
+            } else {
+                atom_pat(p, recovery_set);
+                m.complete(p, RANGE_PAT);
+            }
         }
         // test marco_pat
         // fn main() {
@@ -145,7 +150,21 @@ fn path_pat(p: &mut Parser) -> CompletedMarker {
 fn tuple_pat_fields(p: &mut Parser) {
     assert!(p.at(T!['(']));
     p.bump();
-    pat_list(p, T![')']);
+    while !p.at(EOF) && !p.at(T![')']) {
+        match p.current() {
+            T![..] => p.bump(),
+            _ => {
+                if !p.at_ts(PATTERN_FIRST) {
+                    p.error("expected a pattern");
+                    break;
+                }
+                pattern(p)
+            }
+        }
+        if !p.at(T![')']) {
+            p.expect(T![,]);
+        }
+    }
     p.expect(T![')']);
 }
 
@@ -229,28 +248,30 @@ fn tuple_pat(p: &mut Parser) -> CompletedMarker {
 fn slice_pat(p: &mut Parser) -> CompletedMarker {
     assert!(p.at(T!['[']));
     let m = p.start();
+    // test subslice_pat
+    // fn main() {
+    //     let [a, b..] = [];
+    //     let &[ref a.., ref b] = [];
+    // }
     p.bump();
-    pat_list(p, T![']']);
-    p.expect(T![']']);
-    m.complete(p, SLICE_PAT)
-}
-
-fn pat_list(p: &mut Parser, ket: SyntaxKind) {
-    while !p.at(EOF) && !p.at(ket) {
+    while !p.at(EOF) && !p.at(T![']']) {
         match p.current() {
             T![..] => p.bump(),
             _ => {
                 if !p.at_ts(PATTERN_FIRST) {
                     p.error("expected a pattern");
                     break;
                 }
-                pattern(p)
+                pattern(p);
+                p.eat(T![..]);
             }
         }
-        if !p.at(ket) {
+        if !p.at(T![']']) {
             p.expect(T![,]);
         }
     }
+    p.expect(T![']']);
+    m.complete(p, SLICE_PAT)
 }
 
 // test bind_pat

crates/ra_parser/src/syntax_kind/generated.rs

@@ -165,6 +165,7 @@ pub enum SyntaxKind {
     SLICE_PAT,
     RANGE_PAT,
     LITERAL_PAT,
+    SUBSLICE_PAT,
     TUPLE_EXPR,
     ARRAY_EXPR,
     PAREN_EXPR,
@@ -632,6 +633,7 @@ impl SyntaxKind {
             SLICE_PAT => &SyntaxInfo { name: "SLICE_PAT" },
             RANGE_PAT => &SyntaxInfo { name: "RANGE_PAT" },
             LITERAL_PAT => &SyntaxInfo { name: "LITERAL_PAT" },
+            SUBSLICE_PAT => &SyntaxInfo { name: "SUBSLICE_PAT" },
             TUPLE_EXPR => &SyntaxInfo { name: "TUPLE_EXPR" },
             ARRAY_EXPR => &SyntaxInfo { name: "ARRAY_EXPR" },
             PAREN_EXPR => &SyntaxInfo { name: "PAREN_EXPR" },

crates/ra_syntax/src/grammar.ron

@@ -168,6 +168,7 @@ Grammar(
         "SLICE_PAT",
         "RANGE_PAT",
         "LITERAL_PAT",
+        "SUBSLICE_PAT",
 
         // atoms
         "TUPLE_EXPR",
@@ -686,7 +687,7 @@ Grammar(
         "LifetimeArg": (),
 
         "MacroItems": (
-            traits: [ "ModuleItemOwner", "FnDefOwner" ],            
+            traits: [ "ModuleItemOwner", "FnDefOwner" ],
         ),
 
         "MacroStmts" : (

crates/ra_syntax/tests/data/parser/inline/ok/0137_subslice_pat.rs

@@ -0,0 +1,4 @@
+fn main() {
+    let [a, b..] = [];
+    let &[ref a.., ref b] = [];
+}

crates/ra_syntax/tests/data/parser/inline/ok/0137_subslice_pat.txt

@@ -0,0 +1,69 @@
+SOURCE_FILE@[0; 69)
+  FN_DEF@[0; 68)
+    FN_KW@[0; 2) "fn"
+    WHITESPACE@[2; 3) " "
+    NAME@[3; 7)
+      IDENT@[3; 7) "main"
+    PARAM_LIST@[7; 9)
+      L_PAREN@[7; 8) "("
+      R_PAREN@[8; 9) ")"
+    WHITESPACE@[9; 10) " "
+    BLOCK@[10; 68)
+      L_CURLY@[10; 11) "{"
+      WHITESPACE@[11; 16) "\n    "
+      LET_STMT@[16; 34)
+        LET_KW@[16; 19) "let"
+        WHITESPACE@[19; 20) " "
+        SLICE_PAT@[20; 28)
+          L_BRACK@[20; 21) "["
+          BIND_PAT@[21; 22)
+            NAME@[21; 22)
+              IDENT@[21; 22) "a"
+          COMMA@[22; 23) ","
+          WHITESPACE@[23; 24) " "
+          SUBSLICE_PAT@[24; 27)
+            BIND_PAT@[24; 25)
+              NAME@[24; 25)
+                IDENT@[24; 25) "b"
+            DOTDOT@[25; 27) ".."
+          R_BRACK@[27; 28) "]"
+        WHITESPACE@[28; 29) " "
+        EQ@[29; 30) "="
+        WHITESPACE@[30; 31) " "
+        ARRAY_EXPR@[31; 33)
+          L_BRACK@[31; 32) "["
+          R_BRACK@[32; 33) "]"
+        SEMI@[33; 34) ";"
+      WHITESPACE@[34; 39) "\n    "
+      LET_STMT@[39; 66)
+        LET_KW@[39; 42) "let"
+        WHITESPACE@[42; 43) " "
+        REF_PAT@[43; 60)
+          AMP@[43; 44) "&"
+          SLICE_PAT@[44; 60)
+            L_BRACK@[44; 45) "["
+            SUBSLICE_PAT@[45; 52)
+              BIND_PAT@[45; 50)
+                REF_KW@[45; 48) "ref"
+                WHITESPACE@[48; 49) " "
+                NAME@[49; 50)
+                  IDENT@[49; 50) "a"
+              DOTDOT@[50; 52) ".."
+            COMMA@[52; 53) ","
+            WHITESPACE@[53; 54) " "
+            BIND_PAT@[54; 59)
+              REF_KW@[54; 57) "ref"
+              WHITESPACE@[57; 58) " "
+              NAME@[58; 59)
+                IDENT@[58; 59) "b"
+            R_BRACK@[59; 60) "]"
+        WHITESPACE@[60; 61) " "
+        EQ@[61; 62) "="
+        WHITESPACE@[62; 63) " "
+        ARRAY_EXPR@[63; 65)
+          L_BRACK@[63; 64) "["
+          R_BRACK@[64; 65) "]"
+        SEMI@[65; 66) ";"
+      WHITESPACE@[66; 67) "\n"
+      R_CURLY@[67; 68) "}"
+  WHITESPACE@[68; 69) "\n"