Added new special operators like &= and <<=.

Also made a litle change to scanner function moveOn(): now it moves on
the last char passed and only if there are more than one chars.

operator-assign.go

@@ -183,6 +183,14 @@ func evalOpAssign(ctx ExprContext, opTerm *term) (v any, err error) {
 				v, err = divValues(opTerm, leftValue, rightValue)
 			case SymPercEqual:
 				v, err = remainderValues(opTerm, leftValue, rightValue)
+			case SymAmpersandEqual:
+				v, err = bitwiseAnd(opTerm, leftValue, rightValue)
+			case SymVertBarEqual:
+				v, err = bitwiseOr(opTerm, leftValue, rightValue)
+			case SymDoubleLessEqual:
+				v, err = bitLeftShift(opTerm, leftValue, rightValue)
+			case SymDoubleGreaterEqual:
+				v, err = bitRightShift(opTerm, leftValue, rightValue)
 			default:
 				err = opTerm.Errorf("unsupported assign operator %q", opTerm.source())
 			}
@@ -201,4 +209,9 @@ func init() {
 	registerTermConstructor(SymMinusEqual, newOpAssignTerm)
 	registerTermConstructor(SymStarEqual, newOpAssignTerm)
 	registerTermConstructor(SymSlashEqual, newOpAssignTerm)
+	registerTermConstructor(SymPercEqual, newOpAssignTerm)
+	registerTermConstructor(SymDoubleLessEqual, newOpAssignTerm)
+	registerTermConstructor(SymDoubleGreaterEqual, newOpAssignTerm)
+	registerTermConstructor(SymAmpersandEqual, newOpAssignTerm)
+	registerTermConstructor(SymVertBarEqual, newOpAssignTerm)
 }