cue/ast: allow parentheses as labels

changed:
- parser
- formatter
- compiler
- resolver

Change-Id: I911e22859ad696acbb37bc829154d0294761d5cf
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/9323
Reviewed-by: Paul Jolly <[email protected]>
Reviewed-by: CUE cueckoo <[email protected]>

cue/ast/ast.go

@@ -667,6 +667,7 @@ type ParenExpr struct {
 
 	comments
 	expr
+	label
 }
 
 // A SelectorExpr node represents an expression followed by a selector.

cue/ast/astutil/resolve.go

@@ -281,6 +281,9 @@ func (s *scope) Before(n ast.Node) (w visitor) {
 		}
 
 		switch label := n.(type) {
+		case *ast.ParenExpr:
+			walk(s, label)
+
 		case *ast.Interpolation:
 			walk(s, label)
 

cue/format/node.go

@@ -493,6 +493,9 @@ func (f *formatter) label(l ast.Label, optional bool) {
 	case *ast.ListLit:
 		f.expr(n)
 
+	case *ast.ParenExpr:
+		f.expr(n)
+
 	case *ast.Interpolation:
 		f.expr(n)
 

cue/format/testdata/simplify.golden

@@ -30,6 +30,8 @@ quux: 5
 // Issue #294
 "\("x")": "x"
 
+(x): "foo"
+
 a :: {
 	foo: 2
 	...

cue/format/testdata/simplify.input

@@ -32,6 +32,8 @@ a:
 // Issue #294
 "\("x")": "x"
 
+(x): "foo"
+
 a :: {
     [string]: _
     foo: 2

cue/parser/parser.go

@@ -897,7 +897,8 @@ func (p *parser) parseField() (decl ast.Decl) {
 					return a
 				}
 				switch tok {
-				case token.IDENT, token.LBRACK, token.STRING, token.INTERPOLATION,
+				case token.IDENT, token.LBRACK, token.LPAREN,
+					token.STRING, token.INTERPOLATION,
 					token.NULL, token.TRUE, token.FALSE,
 					token.FOR, token.IF, token.LET, token.IN:
 					return &ast.EmbedDecl{Expr: expr}
@@ -1011,7 +1012,7 @@ func (p *parser) parseLabel(rhs bool) (label ast.Label, expr ast.Expr, decl ast.
 		}
 		expr = ident
 
-	case token.IDENT, token.STRING, token.INTERPOLATION,
+	case token.IDENT, token.STRING, token.INTERPOLATION, token.LPAREN,
 		token.NULL, token.TRUE, token.FALSE, token.IN:
 		expr = p.parseExpr()
 

cue/parser/parser_test.go

@@ -329,6 +329,16 @@ func TestParse(t *testing.T) {
 			a:     { a: 1 }
 		}`,
 		"{[foo=_]: {a: int}, a: {a: 1}}",
+	}, {
+		"dynamic labels",
+		`{
+			(x): a: int
+			x:   "foo"
+			a: {
+				(a.b)
+			}
+		}`,
+		`{(x): {a: int}, x: "foo", a: {(a.b)}}`,
 	}, {
 		"foo",
 		`[

cue/testdata/eval/dynamic_field.txtar

@@ -12,6 +12,15 @@ c: X
 withError: {
     issue799: {key: int32} & {"\(1&2)": 123}
 }
+
+parenExprRefParent: {
+  a: (x): {}
+  x: "foo"
+}
+parenExprRefEqual: {
+  (x): {}
+  x: "foo"
+}
 -- out/eval --
 Errors:
 invalid interpolation: conflicting values 2 and 1:
@@ -34,6 +43,18 @@ Result:
       key: (int){ &(>=-2147483648, <=2147483647, int) }
     }
   }
+  parenExprRefParent: (struct){
+    a: (struct){
+      foo: (struct){
+      }
+    }
+    x: (string){ "foo" }
+  }
+  parenExprRefEqual: (struct){
+    x: (string){ "foo" }
+    foo: (struct){
+    }
+  }
   foo: (struct){
     b: (struct){
       c: (struct){
@@ -69,4 +90,14 @@ Result:
       "\((1 & 2))": 123
     })
   }
+  parenExprRefParent: {
+    a: {
+      〈1;x〉: {}
+    }
+    x: "foo"
+  }
+  parenExprRefEqual: {
+    〈0;x〉: {}
+    x: "foo"
+  }
 }

internal/core/adt/feature.go

@@ -183,7 +183,7 @@ func labelFromValue(c *OpContext, src Expr, v Value) Feature {
 	}
 	switch v.Kind() {
 	case IntKind, NumKind:
-		x, _ := v.(*Num)
+		x, _ := Unwrap(v).(*Num)
 		if x == nil {
 			c.addErrf(IncompleteError, pos(v), msgGround, v, "int")
 			return InvalidLabel
@@ -213,7 +213,7 @@ func labelFromValue(c *OpContext, src Expr, v Value) Feature {
 		}
 
 	case StringKind:
-		x, _ := v.(*String)
+		x, _ := Unwrap(v).(*String)
 		if x == nil {
 			c.addErrf(IncompleteError, pos(v), msgGround, v, "string")
 			return InvalidLabel

internal/core/compile/compile.go

@@ -574,7 +574,17 @@ func (c *compiler) decl(d ast.Decl) adt.Decl {
 				Label:  label,
 			}
 
-		case *ast.Interpolation: // *ast.ParenExpr,
+		case *ast.ParenExpr:
+			if x.Token == token.ISA {
+				c.errf(x, "definitions not supported for dynamic fields")
+			}
+			return &adt.DynamicField{
+				Src:   x,
+				Key:   c.expr(l),
+				Value: value,
+			}
+
+		case *ast.Interpolation:
 			if x.Token == token.ISA {
 				c.errf(x, "definitions not supported for interpolations")
 			}