expressions now support dict data-type

operator-dot.go

@@ -4,6 +4,8 @@
 // operator-dot.go
 package expr
 
+import "fmt"
+
 // -------- dot term
 func newDotTerm(tk *Token) (inst *term) {
 	return &term{
@@ -23,15 +25,13 @@ func evalDot(ctx ExprContext, self *term) (v any, err error) {
 	}
 
 	indexTerm := self.children[1]
-	if !isInteger(rightValue) {
-		err = indexTerm.Errorf("index expression must be integer, got %T", rightValue)
-		return
-	}
-
-	index64, _ := rightValue.(int64)
-	index := int(index64)
 
 	if isList(leftValue) {
+		var index int
+		if index, err = indexTerm.toInt(rightValue, "index expression value must be integer"); err != nil {
+			return
+		}
+
 		list, _ := leftValue.([]any)
 		if index >= 0 && index < len(list) {
 			v = list[index]
@@ -41,6 +41,11 @@ func evalDot(ctx ExprContext, self *term) (v any, err error) {
 			err = indexTerm.Errorf("index %v out of bounds", index)
 		}
 	} else if isString(leftValue) {
+		var index int
+		if index, err = indexTerm.toInt(rightValue, "index expression value must be integer"); err != nil {
+			return
+		}
+
 		s, _ := leftValue.(string)
 		if index >= 0 && index < len(s) {
 			v = string(s[index])
@@ -49,6 +54,12 @@ func evalDot(ctx ExprContext, self *term) (v any, err error) {
 		} else {
 			err = indexTerm.Errorf("index %v out of bounds", index)
 		}
+	} else if isDict(leftValue) {
+		var ok bool
+		d, _ := leftValue.(map[any]any)
+		if v, ok = d[rightValue]; !ok {
+			err = fmt.Errorf("key %v does not belong to the dictionary", rightValue)
+		}
 	} else {
 		err = self.errIncompatibleTypes(leftValue, rightValue)
 	}