获取最后一个内部ng重复索引

    <div ng-repeat="post in vm.post track by $index">
          <button ng-click="vm.remove(post,$index)"></button>
          <div ng-repeat="comment in post.cmt track by comment._id">
               <div ng-repeat="reply in comment track by reply._id">
                    <button ng-click="vm.remove(post,'what shoud I pass here as index')"></button>
        </div>
     </div>
</div>
   vm.remove = function() {
   if (isConfirm) {
       groupFactory.updateGroupMember(data).then(function(response) {
           SweetAlert.swal('Deleted!', response.data.message);
           vm.post.splice(index, 1);
       }, function(error) {
           $scope.showError(error.data.message);
       });
   }
 }

如何在回复的最后一次内部ng重复中获取当前索引,就像在vm中一样。post的删除()