Support if-let in scopes

5 files changed, 108 insertions, 16 deletions

diff --git a/crates/libsyntax2/src/ast/generated.rs b/crates/libsyntax2/src/ast/generated.rs
index 1dd161f52..6891e857c 100644
--- a/crates/libsyntax2/src/ast/generated.rs
+++ b/crates/libsyntax2/src/ast/generated.rs
@@ -141,7 +141,11 @@ impl<'a> AstNode<'a> for BlockExpr<'a> {
     fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
 }
 
-impl<'a> BlockExpr<'a> {}
+impl<'a> BlockExpr<'a> {
+    pub fn block(self) -> Option<Block<'a>> {
+        super::child_opt(self)
+    }
+}
 
 // BreakExpr
 #[derive(Debug, Clone, Copy)]
@@ -197,6 +201,32 @@ impl<'a> AstNode<'a> for CastExpr<'a> {
 
 impl<'a> CastExpr<'a> {}
 
+// Condition
+#[derive(Debug, Clone, Copy)]
+pub struct Condition<'a> {
+    syntax: SyntaxNodeRef<'a>,
+}
+
+impl<'a> AstNode<'a> for Condition<'a> {
+    fn cast(syntax: SyntaxNodeRef<'a>) -> Option<Self> {
+        match syntax.kind() {
+            CONDITION => Some(Condition { syntax }),
+            _ => None,
+        }
+    }
+    fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
+}
+
+impl<'a> Condition<'a> {
+    pub fn pat(self) -> Option<Pat<'a>> {
+        super::child_opt(self)
+    }
+
+    pub fn expr(self) -> Option<Expr<'a>> {
+        super::child_opt(self)
+    }
+}
+
 // ConstDef
 #[derive(Debug, Clone, Copy)]
 pub struct ConstDef<'a> {
@@ -403,7 +433,11 @@ impl<'a> AstNode<'a> for ExprStmt<'a> {
     fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
 }
 
-impl<'a> ExprStmt<'a> {}
+impl<'a> ExprStmt<'a> {
+    pub fn expr(self) -> Option<Expr<'a>> {
+        super::child_opt(self)
+    }
+}
 
 // FieldExpr
 #[derive(Debug, Clone, Copy)]
@@ -504,7 +538,11 @@ impl<'a> AstNode<'a> for ForExpr<'a> {
     fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
 }
 
-impl<'a> ForExpr<'a> {}
+impl<'a> ForExpr<'a> {
+    pub fn body(self) -> Option<Block<'a>> {
+        super::child_opt(self)
+    }
+}
 
 // ForType
 #[derive(Debug, Clone, Copy)]
@@ -540,7 +578,11 @@ impl<'a> AstNode<'a> for IfExpr<'a> {
     fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
 }
 
-impl<'a> IfExpr<'a> {}
+impl<'a> IfExpr<'a> {
+    pub fn condition(self) -> Option<Condition<'a>> {
+        super::child_opt(self)
+    }
+}
 
 // ImplItem
 #[derive(Debug, Clone, Copy)]
@@ -674,7 +716,11 @@ impl<'a> AstNode<'a> for LoopExpr<'a> {
     fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
 }
 
-impl<'a> LoopExpr<'a> {}
+impl<'a> LoopExpr<'a> {
+    pub fn body(self) -> Option<Block<'a>> {
+        super::child_opt(self)
+    }
+}
 
 // MatchArm
 #[derive(Debug, Clone, Copy)]
@@ -1742,5 +1788,13 @@ impl<'a> AstNode<'a> for WhileExpr<'a> {
     fn syntax(self) -> SyntaxNodeRef<'a> { self.syntax }
 }
 
-impl<'a> WhileExpr<'a> {}
+impl<'a> WhileExpr<'a> {
+    pub fn condition(self) -> Option<Condition<'a>> {
+        super::child_opt(self)
+    }
+
+    pub fn body(self) -> Option<Block<'a>> {
+        super::child_opt(self)
+    }
+}
 
diff --git a/crates/libsyntax2/src/ast/mod.rs b/crates/libsyntax2/src/ast/mod.rs
index 6217c5b74..2ebee6a4f 100644
--- a/crates/libsyntax2/src/ast/mod.rs
+++ b/crates/libsyntax2/src/ast/mod.rs
@@ -115,6 +115,18 @@ impl<'a> Module<'a> {
     }
 }
 
+impl<'a> IfExpr<'a> {
+    pub fn then_branch(self) -> Option<Block<'a>> {
+        self.blocks().nth(0)
+    }
+    pub fn else_branch(self) -> Option<Block<'a>> {
+        self.blocks().nth(1)
+    }
+    fn blocks(self) -> impl Iterator<Item=Block<'a>> {
+        children(self)
+    }
+}
+
 fn child_opt<'a, P: AstNode<'a>, C: AstNode<'a>>(parent: P) -> Option<C> {
     children(parent).next()
 }
diff --git a/crates/libsyntax2/src/grammar.ron b/crates/libsyntax2/src/grammar.ron
index f3c3d3036..c9e128462 100644
--- a/crates/libsyntax2/src/grammar.ron
+++ b/crates/libsyntax2/src/grammar.ron
@@ -162,9 +162,10 @@ Grammar(
         "PATH_EXPR",
         "LAMBDA_EXPR",
         "IF_EXPR",
+        "WHILE_EXPR",
+        "CONDITION",
         "LOOP_EXPR",
         "FOR_EXPR",
-        "WHILE_EXPR",
         "CONTINUE_EXPR",
         "BREAK_EXPR",
         "LABEL",
@@ -336,14 +337,27 @@ Grammar(
         "ParenExpr": (),
         "PathExpr": (),
         "LambdaExpr": (),
-        "IfExpr": (),
-        "LoopExpr": (),
-        "ForExpr": (),
-        "WhileExpr": (),
+        "IfExpr": (
+            options: [ ["condition", "Condition"] ]
+        ),
+        "LoopExpr": (
+            options: [ ["body", "Block"] ]
+        ),
+        "ForExpr": (
+            options: [ ["body", "Block"] ]
+        ),
+        "WhileExpr": (
+            options: [
+                ["condition", "Condition"],
+                ["body", "Block"],
+            ]
+        ),
         "ContinueExpr": (),
         "BreakExpr": (),
         "Label": (),
-        "BlockExpr": (),
+        "BlockExpr": (
+            options: [ ["block", "Block"] ]
+        ),
         "ReturnExpr": (),
         "MatchExpr": (),
         "MatchArmList": (),
@@ -432,11 +446,19 @@ Grammar(
         "TypeParamList": ( collections: [ ["type_params", "TypeParam" ] ]),
         "TypeParam": ( traits: ["NameOwner"] ),
         "WhereClause": (),
-        "ExprStmt": (),
+        "ExprStmt": (
+            options: [ ["expr", "Expr"] ]
+        ),
         "LetStmt": ( options: [
             ["pat", "Pat"],
             ["initializer", "Expr"],
         ]),
+        "Condition": (
+            options: [
+                [ "pat", "Pat" ],
+                [ "expr", "Expr" ],
+            ]
+        ),
         "Stmt": (
             enum: ["ExprStmt", "LetStmt"],
         ),
diff --git a/crates/libsyntax2/src/grammar/expressions/atom.rs b/crates/libsyntax2/src/grammar/expressions/atom.rs
index d9c3f998a..bb5402af7 100644
--- a/crates/libsyntax2/src/grammar/expressions/atom.rs
+++ b/crates/libsyntax2/src/grammar/expressions/atom.rs
@@ -237,11 +237,13 @@ fn for_expr(p: &mut Parser, m: Option<Marker>) -> CompletedMarker {
 // test cond
 // fn foo() { if let Some(_) = None {} }
 fn cond(p: &mut Parser) {
+    let m = p.start();
     if p.eat(LET_KW) {
         patterns::pattern(p);
         p.expect(EQ);
     }
-    expr_no_struct(p)
+    expr_no_struct(p);
+    m.complete(p, CONDITION);
 }
 
 // test match_expr
diff --git a/crates/libsyntax2/src/syntax_kinds/generated.rs b/crates/libsyntax2/src/syntax_kinds/generated.rs
index 6a24cb19e..0a22b11c2 100644
--- a/crates/libsyntax2/src/syntax_kinds/generated.rs
+++ b/crates/libsyntax2/src/syntax_kinds/generated.rs
@@ -158,9 +158,10 @@ pub enum SyntaxKind {
     PATH_EXPR,
     LAMBDA_EXPR,
     IF_EXPR,
+    WHILE_EXPR,
+    CONDITION,
     LOOP_EXPR,
     FOR_EXPR,
-    WHILE_EXPR,
     CONTINUE_EXPR,
     BREAK_EXPR,
     LABEL,
@@ -418,9 +419,10 @@ impl SyntaxKind {
             PATH_EXPR => &SyntaxInfo { name: "PATH_EXPR" },
             LAMBDA_EXPR => &SyntaxInfo { name: "LAMBDA_EXPR" },
             IF_EXPR => &SyntaxInfo { name: "IF_EXPR" },
+            WHILE_EXPR => &SyntaxInfo { name: "WHILE_EXPR" },
+            CONDITION => &SyntaxInfo { name: "CONDITION" },
             LOOP_EXPR => &SyntaxInfo { name: "LOOP_EXPR" },
             FOR_EXPR => &SyntaxInfo { name: "FOR_EXPR" },
-            WHILE_EXPR => &SyntaxInfo { name: "WHILE_EXPR" },
             CONTINUE_EXPR => &SyntaxInfo { name: "CONTINUE_EXPR" },
             BREAK_EXPR => &SyntaxInfo { name: "BREAK_EXPR" },
             LABEL => &SyntaxInfo { name: "LABEL" },