/// <summary>
/// 收集子标签。
/// </summary>
/// <param name="tag">指定一个标签实例。</param>
/// <param name="index">指定标签索引。</param>
/// <returns>Tag</returns>
private Tag CollectForTag(Tag tag, ref int index)
{
if (tag.IsClosed) return tag;
if (string.Compare(tag.Name, "if", true) == 0) tag = new TagIf(tag.Line, tag.Col, tag.AttributeValue("test"));
Tag collectTag = tag;
for (index++; index < _Elements.Count; index++)
{
Element elem = _Elements[index];
if (elem is Text)
collectTag.InnerElements.Add(elem);
else if (elem is Expression)
collectTag.InnerElements.Add(elem);
else if (elem is Tag)
{
Tag innerTag = (Tag)elem;
if (string.Compare(innerTag.Name, "else", true) == 0)
{
if (collectTag is TagIf)
{
((TagIf)collectTag).FalseBranch = innerTag;
collectTag = innerTag;
}
else
throw new ParseException("else 标签必须包含在 if 或 elseif 之内。", innerTag.Line, innerTag.Col);
}
else if (string.Compare(innerTag.Name, "elseif", true) == 0)
{
if (collectTag is TagIf)
{
Tag newTag = new TagIf(innerTag.Line, innerTag.Col, innerTag.AttributeValue("test"));
((TagIf)collectTag).FalseBranch = newTag;
collectTag = newTag;
}
else
throw new ParseException("elseif 标签位置不正确。", innerTag.Line, innerTag.Col);
}
else
collectTag.InnerElements.Add(CollectForTag(innerTag, ref index));
}
else if (elem is TagClose)
{
TagClose tagClose = (TagClose)elem;
if (string.Compare(tag.Name, tagClose.Name, true) == 0)
return tag;
throw new ParseException("没有为闭合标签 " + tagClose.Name + " 找到合适的开始标签。", elem.Line, elem.Col);
}
else
throw new ParseException("无效标签： " + elem.GetType().ToString(), elem.Line, elem.Col);
}
throw new ParseException("没有为开始标签 " + tag.Name + " 找到合适的闭合标签。", tag.Line, tag.Col);
}
/// <summary>
/// 处理 If 语句。
/// </summary>
/// <param name="tagIf">包含 if 语句的标签实例。</param>
protected void ProcessIf(TagIf tagIf)
{
bool condition = false;
try
{
object value = this.EvalExpression(tagIf.Test);
condition = Utility.ToBool(value);
}
catch (Exception ex)
{
this.DisplayError("遭遇非法的 If 语句。" + ex.Message,
tagIf.Line, tagIf.Col);
return;
}
if (condition)
this.ProcessElements(tagIf.InnerElements);
else
this.ProcessElement(tagIf.FalseBranch);
}