protected virtual void CreateControlHierarchy(bool useDataSource)

{

IEnumerable data = null; 

int dataItemCount = -1;

if (this.itemsArray != null) 

{ 

    this.itemsArray.Clear();

} 

else

{ 

    this.itemsArray = new ArrayList(); 

} 

if (!useDataSource)

{ 

    dataItemCount = (int) this.ViewState["_!ItemCount"]; 

    if (dataItemCount != -1) 

    { 

        data = new DummyDataSource(dataItemCount); 

        this.itemsArray.Capacity = dataItemCount; 

    } 

} 

else

{ 

    data = this.GetData();

    ICollection is2 = data as ICollection; 

    if (is2 != null) 

    { 

        this.itemsArray.Capacity = is2.Count; 

    } 

} 

if (data != null)

{ 

    int itemIndex = 0; 

    bool flag = this.separatorTemplate != null;//是否有分隔符模版 

    dataItemCount = 0; 

    if (this.headerTemplate != null)

    { 

        this.CreateItem(-1, ListItemType.Header, useDataSource, null);
    } 

    foreach (object obj2 in data) 

    { 

        if (flag && (dataItemCount > 0)) 

        { 

            this.CreateItem(itemIndex - 1, ListItemType.Separator, useDataSource, null);

        } 

        ListItemType itemType = ((itemIndex % 2) == 0) ? ListItemType.Item : ListItemType.AlternatingItem; 

        RepeaterItem item = this.CreateItem(itemIndex, itemType, useDataSource, obj2);//Item和Alter交替创建 

        this.itemsArray.Add(item); 

        dataItemCount++; 

        itemIndex++; 

    } 

    if (this.footerTemplate != null) 

    { 

        this.CreateItem(-1, ListItemType.Footer, useDataSource, null);//创建底部 

    } 

} 

if (useDataSource) 

{ 

    this.ViewState["_!ItemCount"] = (data != null) ? dataItemCount : -1;//给ViewState的ItemCount赋值 

} 

}
能不能给我详细解释一下上面代码的意思?