xmlParent {XML} | R Documentation

## Get parent node of XMLInternalNode

### Description

This operates on an XML node and returns a reference to its parent node within the document tree. This works for an internal, C-level `XMLInternalNode` object created, for examply, using `newXMLNode` and related functions or `xmlTree` or from `xmlTreeParse` with the `useInternalNodes` parameter.

It is possible to find the parent of an R-level XML node when using a tree created with, for example, `xmlHashTree` as the parent information is stored separately.

### Usage

    xmlParent(x)

### Arguments

`x` | an object of class `XMLInternalNode` whose parent is being requested.

### Details

This uses the internal libxml structures to access the parent in the DOM tree. This function is generic so that we can add methods for other types of nodes if we so want in the future.

### Value

An object of class `XMLInternalNode`.

### Author(s)

Duncan Temple Lang

### References

http://www.w3.org/XML

### See Also

`xmlChildren` `xmlTreeParse` `xmlNode`

### Examples

      top = newXMLNode("doc")
      s = newXMLNode("section", attr = c(title = "Introduction"))
      a = newXMLNode("article", s)
      addChildren(top, a)

      xmlName(xmlParent(s))
      xmlName(xmlParent(xmlParent(s)))

        # Find the root node.
      root = a
      while(!is.null(xmlParent(root)))
          root = xmlParent(root)

       # find the names of the parent nodes of each 'h' node.
       # use a global variable to "simplify" things and not use a closure.

      filename = system.file("exampleData", "branch.xml", package = "XML")
      parentNames <- character()
      xmlTreeParse(filename,
                    handlers =
                      list(h = function(x) {
                       parentNames <<- c(parentNames, xmlName(xmlParent(x)))
                      }), useInternalNodes = TRUE)

      table(parentNames)

[Package XML version 1.7-1 Index]