angular的repeat排序問題

多個並列的循環序號連續
HTML：

<div ng-repeat="line in line_list" ng-init="pre_index = preIndex($index)" style="border:1px solid #000">
	<div ng-repeat="item in line.item_list">
			<span>{{pre_index + $index + 1}}</span>
			<span>{{item.text}}</span>
	</div>
</div>

JS:

$scope.preIndex = function(index){
	if(index == 0)return 0;
	var preIndex = 0;
	for(var i = 0 ; i < index ; i++){
		preIndex += $scope.line_list[i].item_list.length;
	}
	return preIndex;
}
$scope.line_list = [
	{
		item_list:[
			{text:"1"},
			{text:"2"},
			{text:"3"},
		]
	},
	{
		item_list:[
			{text:"4"},
			{text:"5"},
			{text:"6"},
		]
	},
	{
		item_list:[
			{text:"7"},
			{text:"8"},
			{text:"9"},
		]
	}
];