Added the dot operator

ucl/ast.go

@@ -57,9 +57,19 @@ type astCmdArg struct {
 	Block      *astBlock      `parser:"| @@"`
 }
 
+type astDotSuffix struct {
+	KeyIdent *astIdentNames `parser:"@@"`
+	Pipeline *astPipeline   `parser:"| LP @@ RP"`
+}
+
+type astDot struct {
+	Arg       astCmdArg      `parser:"@@"`
+	DotSuffix []astDotSuffix `parser:"( DOT @@ )*"`
+}
+
 type astCmd struct {
-	Name astCmdArg   `parser:"@@"`
-	Args []astCmdArg `parser:"@@*"`
+	Name astDot   `parser:"@@"`
+	Args []astDot `parser:"@@*"`
 }
 
 type astPipeline struct {
@@ -84,6 +94,7 @@ var scanner = lexer.MustStateful(lexer.Rules{
 		{"Int", `[-]?[0-9][0-9]*`, nil},
 		{"DOLLAR", `\$`, nil},
 		{"COLON", `\:`, nil},
+		{"DOT", `[.]`, nil},
 		{"LP", `\(`, nil},
 		{"RP", `\)`, nil},
 		{"LS", `\[`, nil},

ucl/builtins.go

@@ -158,6 +158,27 @@ func lenBuiltin(ctx context.Context, args invocationArgs) (object, error) {
 	return intObject(0), nil
 }
 
+func indexLookup(ctx context.Context, obj, elem object) (object, error) {
+	switch v := obj.(type) {
+	case listable:
+		intIdx, ok := elem.(intObject)
+		if !ok {
+			return nil, nil
+		}
+		if int(intIdx) >= 0 && int(intIdx) < v.Len() {
+			return v.Index(int(intIdx)), nil
+		}
+		return nil, nil
+	case hashable:
+		strIdx, ok := elem.(strObject)
+		if !ok {
+			return nil, errors.New("expected string for hashable")
+		}
+		return v.Value(string(strIdx)), nil
+	}
+	return nil, nil
+}
+
 func indexBuiltin(ctx context.Context, args invocationArgs) (object, error) {
 	if err := args.expectArgn(1); err != nil {
 		return nil, err
@@ -165,26 +186,11 @@ func indexBuiltin(ctx context.Context, args invocationArgs) (object, error) {
 
 	val := args.args[0]
 	for _, idx := range args.args[1:] {
-		switch v := val.(type) {
-		case listable:
-			intIdx, ok := idx.(intObject)
-			if !ok {
-				return nil, nil
-			}
-			if int(intIdx) >= 0 && int(intIdx) < v.Len() {
-				val = v.Index(int(intIdx))
-			} else {
-				val = nil
-			}
-		case hashable:
-			strIdx, ok := idx.(strObject)
-			if !ok {
-				return nil, errors.New("expected string for hashable")
-			}
-			val = v.Value(string(strIdx))
-		default:
-			return val, nil
+		newVal, err := indexLookup(ctx, val, idx)
+		if err != nil {
+			return nil, err
 		}
+		val = newVal
 	}
 
 	return val, nil

ucl/eval.go

@@ -71,8 +71,8 @@ func (e evaluator) evalPipeline(ctx context.Context, ec *evalCtx, n *astPipeline
 
 func (e evaluator) evalCmd(ctx context.Context, ec *evalCtx, currentPipe object, ast *astCmd) (object, error) {
 	switch {
-	case ast.Name.Ident != nil:
-		name := ast.Name.Ident.String()
+	case (ast.Name.Arg.Ident != nil) && len(ast.Name.DotSuffix) == 0:
+		name := ast.Name.Arg.Ident.String()
 
 		// Regular command
 		if cmd := ec.lookupInvokable(name); cmd != nil {
@@ -85,7 +85,7 @@ func (e evaluator) evalCmd(ctx context.Context, ec *evalCtx, currentPipe object,
 			return nil, errors.New("unknown command: " + name)
 		}
 	case len(ast.Args) > 0:
-		nameElem, err := e.evalArg(ctx, ec, ast.Name)
+		nameElem, err := e.evalDot(ctx, ec, ast.Name)
 		if err != nil {
 			return nil, err
 		}
@@ -98,7 +98,7 @@ func (e evaluator) evalCmd(ctx context.Context, ec *evalCtx, currentPipe object,
 		return e.evalInvokable(ctx, ec, currentPipe, ast, inv)
 	}
 
-	nameElem, err := e.evalArg(ctx, ec, ast.Name)
+	nameElem, err := e.evalDot(ctx, ec, ast.Name)
 	if err != nil {
 		return nil, err
 	}
@@ -117,7 +117,7 @@ func (e evaluator) evalInvokable(ctx context.Context, ec *evalCtx, currentPipe o
 		argsPtr.Append(currentPipe)
 	}
 	for _, arg := range ast.Args {
-		if ident := arg.Ident; ident != nil && ident.String()[0] == '-' {
+		if ident := arg.Arg.Ident; len(arg.DotSuffix) == 0 && ident != nil && ident.String()[0] == '-' {
 			// Arg switch
 			if kwargs == nil {
 				kwargs = make(map[string]*listObject)
@@ -126,7 +126,7 @@ func (e evaluator) evalInvokable(ctx context.Context, ec *evalCtx, currentPipe o
 			argsPtr = &listObject{}
 			kwargs[ident.String()[1:]] = argsPtr
 		} else {
-			ae, err := e.evalArg(ctx, ec, arg)
+			ae, err := e.evalDot(ctx, ec, arg)
 			if err != nil {
 				return nil, err
 			}
@@ -148,6 +148,33 @@ func (e evaluator) evalMacro(ctx context.Context, ec *evalCtx, hasPipe bool, pip
 	})
 }
 
+func (e evaluator) evalDot(ctx context.Context, ec *evalCtx, n astDot) (object, error) {
+	res, err := e.evalArg(ctx, ec, n.Arg)
+	if err != nil {
+		return nil, err
+	} else if len(n.DotSuffix) == 0 {
+		return res, nil
+	}
+
+	for _, dot := range n.DotSuffix {
+		var idx object
+		if dot.KeyIdent != nil {
+			idx = strObject(dot.KeyIdent.String())
+		} else {
+			idx, err = e.evalPipeline(ctx, ec, dot.Pipeline)
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		res, err = indexLookup(ctx, res, idx)
+		if err != nil {
+			return nil, err
+		}
+	}
+	return res, nil
+}
+
 func (e evaluator) evalArg(ctx context.Context, ec *evalCtx, n astCmdArg) (object, error) {
 	switch {
 	case n.Literal != nil:

ucl/inst_test.go

@@ -60,6 +60,22 @@ func TestInst_Eval(t *testing.T) {
 				three:"3"
 			]`, want: map[string]any{"one": "1", "TWO": "2", "three": "3"}},
 		{desc: "map 4", expr: `firstarg [:]`, want: map[string]any{}},
+
+		// Dots
+		{desc: "dot 1", expr: `set x [1 2 3] ; $x.(0)`, want: 1},
+		{desc: "dot 2", expr: `set x [1 2 3] ; $x.(1)`, want: 2},
+		{desc: "dot 3", expr: `set x [1 2 3] ; $x.(2)`, want: 3},
+		{desc: "dot 4", expr: `set x [1 2 3] ; $x.(3)`, want: nil},
+		{desc: "dot 5", expr: `set x [1 2 3] ; $x.(add 1 1)`, want: 3},
+		{desc: "dot 6", expr: `set x [alpha:"hello" bravo:"world"] ; $x.alpha`, want: "hello"},
+		{desc: "dot 7", expr: `set x [alpha:"hello" bravo:"world"] ; $x.bravo`, want: "world"},
+		{desc: "dot 8", expr: `set x [alpha:"hello" bravo:"world"] ; $x.charlie`, want: nil},
+		{desc: "dot 9", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("alpha")`, want: "hello"},
+		{desc: "dot 10", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("bravo")`, want: "world"},
+		{desc: "dot 11", expr: `set x [alpha:"hello" bravo:"world"] ; $x.("charlie")`, want: nil},
+		{desc: "dot 12", expr: `set x [MORE:"stuff"] ; $x.("more" | toUpper)`, want: "stuff"},
+		{desc: "dot 13", expr: `set x [MORE:"stuff"] ; $x.(toUpper ("more"))`, want: "stuff"},
+		{desc: "dot 14", expr: `set x [MORE:"stuff"] ; x.y`, want: nil},
 	}
 
 	for _, tt := range tests {

ucl/objs.go

@@ -189,7 +189,11 @@ func (ma macroArgs) identIs(ctx context.Context, n int, expectedIdent string) bo
 		return false
 	}
 
-	lit := ma.ast.Args[ma.argShift+n].Ident
+	if len(ma.ast.Args[ma.argShift+n].DotSuffix) != 0 {
+		return false
+	}
+
+	lit := ma.ast.Args[ma.argShift+n].Arg.Ident
 	if lit == nil {
 		return false
 	}
@@ -202,7 +206,11 @@ func (ma *macroArgs) shiftIdent(ctx context.Context) (string, bool) {
 		return "", false
 	}
 
-	lit := ma.ast.Args[ma.argShift].Ident
+	if len(ma.ast.Args[ma.argShift].DotSuffix) != 0 {
+		return "", false
+	}
+
+	lit := ma.ast.Args[ma.argShift].Arg.Ident
 	if lit != nil {
 		ma.argShift += 1
 		return lit.String(), true
@@ -215,7 +223,7 @@ func (ma macroArgs) evalArg(ctx context.Context, n int) (object, error) {
 		return nil, errors.New("not enough arguments") // FIX
 	}
 
-	return ma.eval.evalArg(ctx, ma.ec, ma.ast.Args[ma.argShift+n])
+	return ma.eval.evalDot(ctx, ma.ec, ma.ast.Args[ma.argShift+n])
 }
 
 func (ma macroArgs) evalBlock(ctx context.Context, n int, args []object, pushScope bool) (object, error) {