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\name{XMLInternalDocument-class}
\docType{class}
\alias{XMLAbstractDocument-class} %XXX put somewhere else.
\alias{XMLInternalDocument-class}
\alias{HTMLInternalDocument-class}
\alias{coerce,XMLInternalNode,XMLInternalDocument-method}
\alias{coerce,XMLInternalDocument,XMLInternalNode-method}
\alias{coerce,XMLDocument,XMLInternalDocument-method}
\title{Class to represent reference to C-level data structure for an XML
document}
\description{
This class is used to provide a handle/reference to a C-level
data structure that contains the information from parsing
parsing XML content.
This leaves the nodes in the DOM or tree as C-level nodes
rather than converting them to explicit R \code{XMLNode}
objects. One can then operate on this tree in much the same
way as one can the \code{XMLNode} representations,
but we a) avoid copying the nodes to R, and b) can navigate
the tree both down and up using \code{\link{xmlParent}}
giving greater flexibility.
Most importantly, one can use an \code{XMLInternalDocument}
class object with an XPath expression to easily and relatively efficiently
find nodes within a document that satisfy some criterion.
See \code{\link{getNodeSet}}.
}
\section{Objects from the Class}{
Objects of this type are created via
\code{\link{xmlTreeParse}}
and \code{\link{htmlTreeParse}}
with the argument \code{useInternalNodes} given as \code{TRUE}.
}
\section{Extends}{
Class \code{\linkS4class{oldClass}}, directly.
}
\section{Methods}{
There are methods to serialize (dump) a document to a file or as a
string, and to coerce it to a node by finding the top-level node of
the document.
There are functions to search the document for nodes specified by
an XPath expression.
}
\references{
XPath \url{https://www.w3.org/TR/xpath/}
}
\seealso{
\code{\link{xmlTreeParse}}
\code{\link{htmlTreeParse}}
\code{\link{getNodeSet}}
}
\examples{
f = system.file("exampleData", "mtcars.xml", package="XML")
doc = xmlParse(f)
getNodeSet(doc, "//variables[@count]")
getNodeSet(doc, "//record")
getNodeSet(doc, "//record[@id='Mazda RX4']")
# free(doc)
}
\keyword{classes}
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