code: function(data){
          var _retinaObject;
          var _data = [];
          var _retinaImageList = [];
          var _retinaSliceList =[];
          var _regex = new RegExp('background-image:[\\s]*url\\(["\']?(?!http[s]?|/)[^;]*?(slice[\\w\\d\\s!./\\-\\_@]*\\.[\\w?#]+)["\']?\\)[^;}]*;?', 'ig');
          var _rregex = new RegExp('.*(slice\\/[\\w\\d\\s!./\\-\\_@]*)\\.([\\w?#]+)["\']?\\)[^;}]*;?', 'ig');
          RegExp.escape = function (s) {
              return s.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&')
          };
          _data = data.match(_regex);
          if(_data !== null){
              for(var i=0;i<_data.length;i++){
                  var _slice = _data[i];
                  var _retinaSlice = _slice.replace(_rregex,"$1")+"@2x."+_slice.replace(_rregex,"$2");
                  var _retinaSlicePath = _rootPath +"/"+_retinaSlice;
                  if(fileExists(_retinaSlicePath)){
                      var _regexClassNameString = '(\\.?[^}]*?)\\s?{\\s?[^}]*?' + RegExp.escape(_slice);
                      var _regexClassName = new RegExp(_regexClassNameString, 'ig');
                      var _classNameResult = data.match(_regexClassName);
                      var _className = _classNameResult[0].replace(_regexClassName, '$1');
                      var _retinaItem = new Object();
                      _retinaImageList.push(_retinaSlicePath);
                      _retinaItem.className = _className;
                      _retinaSliceList[_retinaSlicePath] = _retinaItem;
                  }
              }
          }
          _retinaObject = {
              slice:_retinaImageList,
              slicekey:_retinaSliceList
          }
          return _retinaObject;
      }
docs: [_getRetinaClassSliceHandler 获取retina的图片和对应的class]
  @param  {[string]} data [样式文件转换为string流的数据]
  @return {[object]}      [返回retina图片数组和class数组]