fix: change Macro.Expand() signature

Author: tyru

dsl/op/array.go

@@ -21,6 +21,6 @@ func (*arrayOp) String() string {
 }
 
 // Execute executes "$array" operation
-func (*arrayOp) Expand(args []types.Value) (types.Value, error) {
-	return types.NewArray(args, types.AnyValue), nil
+func (*arrayOp) Expand(args []types.Value) (types.Value, func(), error) {
+	return types.NewArray(args, types.AnyValue), noRollback, nil
 }

dsl/op/invert.go

@@ -21,9 +21,10 @@ func (*invertOp) String() string {
 }
 
 // Execute executes "$invert" operation
-func (*invertOp) Expand(args []types.Value) (types.Value, error) {
+func (*invertOp) Expand(args []types.Value) (types.Value, func(), error) {
 	if err := signature(types.AnyValue).check(args); err != nil {
-		return nil, err
+		return nil, noRollback, err
 	}
-	return args[0].Invert()
+	val, err := args[0].Invert()
+	return val, noRollback, err
 }

dsl/op/rollback.go

@@ -0,0 +1,3 @@
+package op
+
+var noRollback = func() {}

dsl/parse.go

@@ -52,7 +52,8 @@ func parseArray(array []interface{}) (types.Value, error) {
 		args = append(args, v)
 	}
 	if macro, exists := op.LookupMacro(opName); exists {
-		return macro.Expand(args)
+		val, _, err := macro.Expand(args)
+		return val, err
 	}
 	if fn, exists := op.LookupFunc(opName); exists {
 		return fn.Bind(args...)

dsl/types/op.go

@@ -24,5 +24,5 @@ type Macro interface {
 
 	// Expand expands this expression (operator + args).
 	// If argument type or arity is different, this returns non-nil error.
-	Expand(args []Value) (Value, error)
+	Expand(args []Value) (val Value, rollback func(), err error)
 }