made some interfaces exportable and fixed/enhaaced some selector operator versions

parser.go

@@ -12,10 +12,10 @@ import (
 //-------- parser
 
 type parser struct {
-	ctx exprContext
+	ctx ExprContext
 }
 
-func NewParser(ctx exprContext) (p *parser) {
+func NewParser(ctx ExprContext) (p *parser) {
 	p = &parser{
 		ctx: ctx,
 	}
@@ -246,9 +246,9 @@ func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef
 				currentTerm, err = tree.addToken2(tk)
 			}
 		case SymQuestion:
-			if selectorTerm != nil {
+			/*if selectorTerm != nil {
 				err = tk.Errorf("nested selectors must be enclosed in parentheses")
-			} else if selectorTerm, err = self.parseSelector(scanner, tree, allowVarRef); err == nil {
+			} else*/if selectorTerm, err = self.parseSelector(scanner, tree, allowVarRef); err == nil {
 				currentTerm = selectorTerm
 			}
 		case SymColon, SymDoubleColon:
@@ -259,6 +259,9 @@ func (self *parser) parseGeneral(scanner *scanner, allowForest bool, allowVarRef
 				selectorTerm.children = append(selectorTerm.children, caseTerm)
 				caseTerm.parent = selectorTerm
 				currentTerm = caseTerm
+				if tk.Sym == SymDoubleColon {
+					selectorTerm = nil
+				}
 			}
 			//resetSelector = tk.Sym == SymDoubleColon
 		default: