/// <summary>
/// 获取此产生式结点列表（候选式）的复制品
/// </summary>
/// <returns></returns>
public object Clone()
{
var result = new ProductionNodeList();
result.AddRange(
from item in this
select(item.Clone() as ProductionNode));
return(result);
}
/// <summary>
/// From
/// </summary>
/// <param name="xProductionNodeList"></param>
/// <returns></returns>
public static ProductionNodeList From(XElement xProductionNodeList)
{
if (xProductionNodeList == null)
{
return(null);
}
if (xProductionNodeList.Name != strCandidate)
{
return(null);
}
var result = new ProductionNodeList();
result.AddRange(
from item in xProductionNodeList.Elements(ProductionNode.strProductionNode)
select ProductionNode.From(item)
);
return(result);
}