如何在 HXT 中提取 XML 树的特定分支



举个例子:

<pous>
  <pou>
    <interface>
      ...
    </interface>
    <body>
      <FBD>
        ...
      </FBD>
    </body>
  </pou>
  <pou>
    <interface>
      ...
    </interface>
    <body>
      <SFC>
        ...
      </SFC>
    </body>
  </pou>
</pous>

我知道如何使用 atTag 函数获取所有"pou":

atTag:: (ArrowXml a) => String -> a XmlTree XmlTree
atTag tag = deep (isElem >>> hasName tag)

但是如何仅提取带有SFC标签的" pou"呢?有没有一种干净的方法可以做到这一点?

提前谢谢你!

您想在本例中使用filterA

application
    = processChildren
    $ getChildren                    -- Gets the children of "pous"
    >>> filterA hasSFC
    where hasSFC =  hasName "pou"    -- Include all "pou" elements
                >>> getChildren      -- that have children
                >>> getChildren      -- that have children
                >>> hasName "SFC"    -- that have a "SFC" element
main = do
    runX $
        readDocument [] "input.xml" >>>
        application                 >>>
        writeDocument [withIndent yes] "output.xml"

尝试使用 Haskell XPath 和:

/*/pou[body[SFC]]

进一步参考"XPath 查找具有特定子节点的所有元素"

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