Parse arbitrarily complex box patterns.

crates/ra_hir/src/expr.rs

@@ -1020,6 +1020,7 @@ where
             }
 
             // FIXME: implement
+            ast::Pat::BoxPat(_) => Pat::Missing,
             ast::Pat::LiteralPat(_) => Pat::Missing,
             ast::Pat::SlicePat(_) | ast::Pat::RangePat(_) => Pat::Missing,
         };

crates/ra_parser/src/grammar/expressions/atom.rs

@@ -414,8 +414,6 @@ pub(crate) fn match_arm_list(p: &mut Parser) {
 //         X | Y if Z => (),
 //         | X | Y if Z => (),
 //         | X => (),
-//         box X => (),
-//         Some(box X) => (),
 //     };
 // }
 fn match_arm(p: &mut Parser) -> BlockLike {

crates/ra_parser/src/grammar/patterns.rs

@@ -56,37 +56,33 @@ const PAT_RECOVERY_SET: TokenSet =
     token_set![LET_KW, IF_KW, WHILE_KW, LOOP_KW, MATCH_KW, R_PAREN, COMMA];
 
 fn atom_pat(p: &mut Parser, recovery_set: TokenSet) -> Option<CompletedMarker> {
-    let la0 = p.nth(0);
-    let la1 = p.nth(1);
-    if la0 == T![ref]
-        || la0 == T![mut]
-        || la0 == T![box]
-        || (la0 == IDENT && !(la1 == T![::] || la1 == T!['('] || la1 == T!['{'] || la1 == T![!]))
-    {
-        return Some(bind_pat(p, true));
-    }
-    if paths::is_use_path_start(p) {
-        return Some(path_pat(p));
-    }
+    // Checks the token after an IDENT to see if a pattern is a path (Struct { .. }) or macro
+    // (T![x]).
+    let is_path_or_macro_pat =
+        |la1| la1 == T![::] || la1 == T!['('] || la1 == T!['{'] || la1 == T![!];
 
-    if is_literal_pat_start(p) {
-        return Some(literal_pat(p));
-    }
+    let m = match p.nth(0) {
+        T![box] => box_pat(p),
+        T![ref] | T![mut] | IDENT if !is_path_or_macro_pat(p.nth(1)) => bind_pat(p, true),
+
+        _ if paths::is_use_path_start(p) => path_pat(p),
+        _ if is_literal_pat_start(p) => literal_pat(p),
 
-    let m = match la0 {
         T![_] => placeholder_pat(p),
         T![&] => ref_pat(p),
         T!['('] => tuple_pat(p),
         T!['['] => slice_pat(p),
+
         _ => {
             p.err_recover("expected pattern", recovery_set);
             return None;
         }
     };
+
     Some(m)
 }
 
-fn is_literal_pat_start(p: &mut Parser) -> bool {
+fn is_literal_pat_start(p: &Parser) -> bool {
     p.at(T![-]) && (p.nth(1) == INT_NUMBER || p.nth(1) == FLOAT_NUMBER)
         || p.at_ts(expressions::LITERAL_FIRST)
 }
@@ -165,6 +161,9 @@ fn record_field_pat_list(p: &mut Parser) {
             T![..] => p.bump(),
             IDENT if p.nth(1) == T![:] => record_field_pat(p),
             T!['{'] => error_block(p, "expected ident"),
+            T![box] => {
+                box_pat(p);
+            }
             _ => {
                 bind_pat(p, false);
             }
@@ -261,11 +260,9 @@ fn pat_list(p: &mut Parser, ket: SyntaxKind) {
 //     let ref mut d = ();
 //     let e @ _ = ();
 //     let ref mut f @ g @ _ = ();
-//     let box i = Box::new(1i32);
 // }
 fn bind_pat(p: &mut Parser, with_at: bool) -> CompletedMarker {
     let m = p.start();
-    p.eat(T![box]);
     p.eat(T![ref]);
     p.eat(T![mut]);
     name(p);
@@ -274,3 +271,17 @@ fn bind_pat(p: &mut Parser, with_at: bool) -> CompletedMarker {
     }
     m.complete(p, BIND_PAT)
 }
+
+// test box_pat
+// fn main() {
+//     let box i = ();
+//     let box Outer { box i, j: box Inner(box &x) } = ();
+//     let box ref mut i = ();
+// }
+fn box_pat(p: &mut Parser) -> CompletedMarker {
+    assert!(p.at(T![box]));
+    let m = p.start();
+    p.bump();
+    pattern(p);
+    m.complete(p, BOX_PAT)
+}

crates/ra_parser/src/syntax_kind/generated.rs

@@ -149,6 +149,7 @@ pub enum SyntaxKind {
     IMPL_TRAIT_TYPE,
     DYN_TRAIT_TYPE,
     REF_PAT,
+    BOX_PAT,
     BIND_PAT,
     PLACEHOLDER_PAT,
     PATH_PAT,

crates/ra_syntax/src/ast/generated.rs

@@ -307,6 +307,33 @@ impl BlockExpr {
     }
 }
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
+pub struct BoxPat {
+    pub(crate) syntax: SyntaxNode,
+}
+impl AstNode for BoxPat {
+    fn can_cast(kind: SyntaxKind) -> bool {
+        match kind {
+            BOX_PAT => true,
+            _ => false,
+        }
+    }
+    fn cast(syntax: SyntaxNode) -> Option<Self> {
+        if Self::can_cast(syntax.kind()) {
+            Some(Self { syntax })
+        } else {
+            None
+        }
+    }
+    fn syntax(&self) -> &SyntaxNode {
+        &self.syntax
+    }
+}
+impl BoxPat {
+    pub fn pat(&self) -> Option<Pat> {
+        AstChildren::new(&self.syntax).next()
+    }
+}
+#[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub struct BreakExpr {
     pub(crate) syntax: SyntaxNode,
 }
@@ -2063,6 +2090,7 @@ impl ParenType {
 #[derive(Debug, Clone, PartialEq, Eq, Hash)]
 pub enum Pat {
     RefPat(RefPat),
+    BoxPat(BoxPat),
     BindPat(BindPat),
     PlaceholderPat(PlaceholderPat),
     PathPat(PathPat),
@@ -2078,6 +2106,11 @@ impl From<RefPat> for Pat {
         Pat::RefPat(node)
     }
 }
+impl From<BoxPat> for Pat {
+    fn from(node: BoxPat) -> Pat {
+        Pat::BoxPat(node)
+    }
+}
 impl From<BindPat> for Pat {
     fn from(node: BindPat) -> Pat {
         Pat::BindPat(node)
@@ -2126,14 +2159,15 @@ impl From<LiteralPat> for Pat {
 impl AstNode for Pat {
     fn can_cast(kind: SyntaxKind) -> bool {
         match kind {
-            REF_PAT | BIND_PAT | PLACEHOLDER_PAT | PATH_PAT | RECORD_PAT | TUPLE_STRUCT_PAT
-            | TUPLE_PAT | SLICE_PAT | RANGE_PAT | LITERAL_PAT => true,
+            REF_PAT | BOX_PAT | BIND_PAT | PLACEHOLDER_PAT | PATH_PAT | RECORD_PAT
+            | TUPLE_STRUCT_PAT | TUPLE_PAT | SLICE_PAT | RANGE_PAT | LITERAL_PAT => true,
             _ => false,
         }
     }
     fn cast(syntax: SyntaxNode) -> Option<Self> {
         let res = match syntax.kind() {
             REF_PAT => Pat::RefPat(RefPat { syntax }),
+            BOX_PAT => Pat::BoxPat(BoxPat { syntax }),
             BIND_PAT => Pat::BindPat(BindPat { syntax }),
             PLACEHOLDER_PAT => Pat::PlaceholderPat(PlaceholderPat { syntax }),
             PATH_PAT => Pat::PathPat(PathPat { syntax }),
@@ -2150,6 +2184,7 @@ impl AstNode for Pat {
     fn syntax(&self) -> &SyntaxNode {
         match self {
             Pat::RefPat(it) => &it.syntax,
+            Pat::BoxPat(it) => &it.syntax,
             Pat::BindPat(it) => &it.syntax,
             Pat::PlaceholderPat(it) => &it.syntax,
             Pat::PathPat(it) => &it.syntax,

crates/ra_syntax/src/grammar.ron

@@ -158,6 +158,7 @@ Grammar(
         "DYN_TRAIT_TYPE",
 
         "REF_PAT",
+        "BOX_PAT",
         "BIND_PAT",
         "PLACEHOLDER_PAT",
         "PATH_PAT",
@@ -523,6 +524,7 @@ Grammar(
         ),
 
         "RefPat": ( options: [ "Pat" ]),
+        "BoxPat": ( options: [ "Pat" ]),
         "BindPat": (
             options: [ "Pat" ],
             traits: ["NameOwner"]
@@ -552,6 +554,7 @@ Grammar(
         "Pat": (
             enum: [
                 "RefPat",
+                "BoxPat",
                 "BindPat",
                 "PlaceholderPat",
                 "PathPat",

crates/ra_syntax/test_data/parser/err/0034_bad_box_pattern.rs

@@ -0,0 +1,6 @@
+fn main() {
+    let ref box i = ();
+    let mut box i = ();
+    let ref mut box i = ();
+}
+

crates/ra_syntax/test_data/parser/err/0034_bad_box_pattern.txt

@@ -0,0 +1,95 @@
+SOURCE_FILE@[0; 91)
+  FN_DEF@[0; 89)
+    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; 89)
+      L_CURLY@[10; 11) "{"
+      WHITESPACE@[11; 16) "\n    "
+      LET_STMT@[16; 27)
+        LET_KW@[16; 19) "let"
+        WHITESPACE@[19; 20) " "
+        BIND_PAT@[20; 27)
+          REF_KW@[20; 23) "ref"
+          WHITESPACE@[23; 24) " "
+          ERROR@[24; 27)
+            BOX_KW@[24; 27) "box"
+      WHITESPACE@[27; 28) " "
+      EXPR_STMT@[28; 35)
+        BIN_EXPR@[28; 34)
+          PATH_EXPR@[28; 29)
+            PATH@[28; 29)
+              PATH_SEGMENT@[28; 29)
+                NAME_REF@[28; 29)
+                  IDENT@[28; 29) "i"
+          WHITESPACE@[29; 30) " "
+          EQ@[30; 31) "="
+          WHITESPACE@[31; 32) " "
+          TUPLE_EXPR@[32; 34)
+            L_PAREN@[32; 33) "("
+            R_PAREN@[33; 34) ")"
+        SEMI@[34; 35) ";"
+      WHITESPACE@[35; 40) "\n    "
+      LET_STMT@[40; 51)
+        LET_KW@[40; 43) "let"
+        WHITESPACE@[43; 44) " "
+        BIND_PAT@[44; 51)
+          MUT_KW@[44; 47) "mut"
+          WHITESPACE@[47; 48) " "
+          ERROR@[48; 51)
+            BOX_KW@[48; 51) "box"
+      WHITESPACE@[51; 52) " "
+      EXPR_STMT@[52; 59)
+        BIN_EXPR@[52; 58)
+          PATH_EXPR@[52; 53)
+            PATH@[52; 53)
+              PATH_SEGMENT@[52; 53)
+                NAME_REF@[52; 53)
+                  IDENT@[52; 53) "i"
+          WHITESPACE@[53; 54) " "
+          EQ@[54; 55) "="
+          WHITESPACE@[55; 56) " "
+          TUPLE_EXPR@[56; 58)
+            L_PAREN@[56; 57) "("
+            R_PAREN@[57; 58) ")"
+        SEMI@[58; 59) ";"
+      WHITESPACE@[59; 64) "\n    "
+      LET_STMT@[64; 79)
+        LET_KW@[64; 67) "let"
+        WHITESPACE@[67; 68) " "
+        BIND_PAT@[68; 79)
+          REF_KW@[68; 71) "ref"
+          WHITESPACE@[71; 72) " "
+          MUT_KW@[72; 75) "mut"
+          WHITESPACE@[75; 76) " "
+          ERROR@[76; 79)
+            BOX_KW@[76; 79) "box"
+      WHITESPACE@[79; 80) " "
+      EXPR_STMT@[80; 87)
+        BIN_EXPR@[80; 86)
+          PATH_EXPR@[80; 81)
+            PATH@[80; 81)
+              PATH_SEGMENT@[80; 81)
+                NAME_REF@[80; 81)
+                  IDENT@[80; 81) "i"
+          WHITESPACE@[81; 82) " "
+          EQ@[82; 83) "="
+          WHITESPACE@[83; 84) " "
+          TUPLE_EXPR@[84; 86)
+            L_PAREN@[84; 85) "("
+            R_PAREN@[85; 86) ")"
+        SEMI@[86; 87) ";"
+      WHITESPACE@[87; 88) "\n"
+      R_CURLY@[88; 89) "}"
+  WHITESPACE@[89; 91) "\n\n"
+error 24: expected a name
+error 27: expected SEMI
+error 48: expected a name
+error 51: expected SEMI
+error 76: expected a name
+error 79: expected SEMI

crates/ra_syntax/test_data/parser/inline/ok/0066_match_arm.rs

@@ -5,7 +5,5 @@ fn foo() {
         X | Y if Z => (),
         | X | Y if Z => (),
         | X => (),
-        box X => (),
-        Some(box X) => (),
     };
 }