查找符合条件的最近的祖先/兄弟姐妹 [英] Find nearest ancestor/sibling that matches criteria

问题描述

我有 XML，它由容器节点组成，其中包含各种子节点，包括其他容器节点.示例 XML 看起来像...

I have XML that is composed of container nodes holding various child nodes including other container nodes. Sample XML would look like...

<CONTAINER>
    <SEARCHFOR />
    <ITEM/>
    <ITEM/>
    <ITEM/>
    <ITEM/>
    <ITEM/>
    <CONTAINER>
        <SEARCHFOR />
        <ITEM/>
        <ITEM/>
        <CONTAINER>
            <SEARCHFOR />
            <ITEM id="1" />
            <ITEM/>
            <ITEM/>
            <CONTAINER>
                <ITEM id="2" />
            </CONTAINER>
        </CONTAINER>
    </CONTAINER>
</CONTAINER>

我想找到与 id=2 的 ITEM 最接近(在范围内)的 SEARCHFOR 节点.SEARCHFOR 节点可以是 ITEM 的前同级或祖先 CONTAINER 节点的子级.我有一个 XPath 表达式，可以定位范围内与条件匹配的所有 SEARCHFOR 节点，但我似乎无法让它只返回最近的单个元素.

I'd like to find the SEARCHFOR node that is nearest (in scope) to the ITEM having id=2. The SEARCHFOR node can be a preceding-sibling of ITEM or a child of an ancestor CONTAINER node. I have an XPath expression that can locate all SEARCHFOR nodes that are in scope that match the criteria, but I can't seem to get it to only return the single element that is nearest.

//ITEM[@id="2"]/ancestor::CONTAINER/SEARCHFOR

我正在 Sketchpath 中进行测试，并将使用可以处理 XPath 2.0 的 XML 解析器在 Delphi 中实现它，因此语法也是可以接受的.我可以通过获取我的结果并使用 Delphi 来获得感兴趣的结果在代码中完成此操作，但如果可能的话，我真的需要在 XPath 本身中完成此操作以进行我的实现.任何帮助表示赞赏.

I am testing in Sketchpath and will be implementing this in Delphi using an XML parser that can handle XPath 2.0 so that syntax is also acceptable. I can do this in code by getting my results and using Delphi to get the one of interest, but if at all possible I really need this to be done within the XPath itself for my implementation. Any help is appreciated.

谢谢，迈克尔

推荐答案

也许这个 XPath 2.0 表达式可以回答你的问题:

Maybe this XPath 2.0 expression answers your question :

(//ITEM[@id='2']/(ancestor::CONTAINER/SEARCHFOR|preceding-sibling::SEARCHFOR))[last()]

它的工作原理是按文档顺序构建一系列元素，然后选择最后一个，也就是根据您的描述，最接近的(如果我没猜错的话).

It works by building a sequence of elements in document order, then it chooses the last one, which is, given your description, the nearest (if I get you right).

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