XML::LibXML::Reader 1.63

XML::LibXML::Reader is a Perl interface to libxml2 pull parser.

SYNOPSIS

use XML::LibXML::Reader;

$reader = new XML::LibXML::Reader("file.xml")
or die "cannot read file.xmln";
while ($reader->read) {
processNode($reader);
}


sub processNode {
$reader = shift;
printf "%d %d %s %dn", ($reader->depth,
$reader->nodeType,
$reader->name,
$reader->isEmptyElement);
}
or
$reader = new XML::LibXML::Reader("file.xml")
or die "cannot read file.xmln";
$reader->preservePattern(//table/tr);
$reader->finish;
print $reader->document->toString(1);

This is a perl interface to libxml2s pull-parser implementation xmlTextReader http://xmlsoft.org/html/libxml-xmlreader.html. This feature requires at least libxml2-2.6.21. Pull-parser (StAX in Java, XmlReader in C#) use an iterator approach to parse a xml-file. They are easier to program than event-based parser (SAX) and much more lightweight than tree-based parser (DOM), which load the complete tree into memory.

The Reader acts as a cursor going forward on the document stream and stopping at each node in the way. At every point DOM-like methods of the Reader object allow to examine the current node (name, namespace, attributes, etc.)

The users code keeps control of the progress and simply calls the read() function repeatedly to progress to the next node in the document order. Other functions provide means for skipping complete sub-trees, or nodes until a specific element, etc.

At every time, only a very limited portion of the document is kept in the memory, which makes the API more memory-efficient than using DOM. However, it is also possible to mix Reader with DOM. At every point the user may copy the current node (optionally expanded into a complete sub-tree) from the processed document to another DOM tree, or to instruct the Reader to collect sub-document in form of a DOM tree consisting of selected nodes.

Reader API also supports namespaces, xml:base, entity handling, and DTD validation. Schema and RelaxNG validation support will probably be added in some later revision of the Perl interface.

The naming of methods compared to libxml2 and C# XmlTextReader has been changed slightly to match the conventions of XML::LibXML. Some functions have been changed or added with respect to the C interface.