NAME

       XML::XPath - Parse and evaluate XPath statements.

VERSION

       Version 1.42

DESCRIPTION

       This module aims to comply exactly to the XPath specification at
       http://www.w3.org/TR/xpath and yet allow extensions to be added in the form of
       functions.Modules such as XSLT and XPointer may need to do this as they support
       functionality beyond XPath.

SYNOPSIS

           use XML::XPath;
           use XML::XPath::XMLParser;

           my $xp = XML::XPath->new(filename => 'test.xhtml');

           my $nodeset = $xp->find('/html/body/p'); # find all paragraphs

           foreach my $node ($nodeset->get_nodelist) {
               print "FOUND\n\n",
                   XML::XPath::XMLParser::as_string($node),
                   "\n\n";
           }

DETAILS

       There is an awful lot to  all  of  this, so bear with it - if you stick it out it should
       be worth it. Please get a good understanding of XPath by reading  the spec before asking
       me questions. All of the classes and parts  herein are named to  be synonymous  with  the
       names in  the  specification, so consult that if you don't understand why I'm doing
       something in the code.

METHODS

       The API of XML::XPath itself is extremely simple to allow you to get going almost
       immediately. The deeper API's are more complex, but you  shouldn't  have to touch most of
       that.

   new()
       This  constructor follows  the often seen named parameter method call. Parameters you can
       use are: filename, parser, xml, ioref and context. The filename parameter specifies  an
       XML  file to parse. The xml parameter specifies a string to parse, and the ioref parameter
       specifies  an ioref to  parse. The context  option allows you to specify a context node.
       The context node has to be in the format of a node as specified in XML::XPath::XMLParser.
       The 4  parameters  filename, xml, ioref and context are mutually exclusive - you should
       only  specify one (if you specify anything other than context, the context node is the
       root of your document).  The parser  option  allows  you to pass in an already prepared
       XML::Parser object, to save you having to create more than one in your application (if,
       for example, you are doing more than just XPath).

           my $xp = XML::XPath->new( context => $node );

       It is very much recommended that you use only 1 XPath object  throughout the life of  your
       application. This is because the object (and it's sub-objects) maintain certain  bits  of
       state information that will be useful (such as XPath variables) to later  calls  to
       find().  It's also a good idea because you'll use less memory this way.

   find($path, [$context])
       The find function takes an XPath expression (a string) and returns either an
       XML::XPath::NodeSet object  containing the nodes it found (or empty if no nodes matched
       the path), or one of XML::XPath::Literal (a string), XML::XPath::Number or
       XML::XPath::Boolean.  It should always return something - and you can use ->isa()  to find
       out  what it returned. If you need to check how many nodes it found you should check
       $nodeset->size.  See XML::XPath::NodeSet. An optional second parameter of a context node
       allows you to use this method repeatedly, for example XSLT needs to do this.

   findnodes($path, [$context])
       Returns a list of nodes found by $path, optionally in context $context. In scalar context
       returns an XML::XPath::NodeSet object.

   matches($node, $path, [$context])
       Returns true if the node matches the path (optionally in context $context).

   findnodes_as_string($path, [$context])
       Returns the nodes found reproduced as XML.The result isn't guaranteed to be valid XML
       though.

   findvalue($path, [$context])
       Returns either a "XML::XPath::Literal", a "XML::XPath::Boolean" or a "XML::XPath::Number"
       object.If the path returns a NodeSet,$nodeset->to_literal is called automatically for you
       (and thus a "XML::XPath::Literal" is returned).Note that for each of the objects
       stringification is overloaded, so you can just print the  value found, or manipulate it in
       the ways you would a normal perl value (e.g. using regular expressions).

   exists($path, [$context])
       Returns true if the given path exists.

   getNodeText($path)
       Returns the XML::XPath::Literal for a particular XML node. Returns a string if exists or
       '' (empty string) if the node doesn't exist.

   setNodeText($path, $text)
       Sets the text string for a particular XML node.  The node can be an element or an
       attribute. If the node to be set is an attribute, and the attribute node does not exist,
       it will be created automatically.

   createNode($path)
       Creates the node matching the $path given. If part of the path given or all of the path do
       not exist, the necessary nodes will be created automatically.

   set_namespace($prefix, $uri)
       Sets the namespace prefix mapping to the uri.

       Normally in "XML::XPath" the prefixes in XPath node test take their context from the
       current node. This means that foo:bar will always match an element  <foo:bar> regardless
       of  the  namespace that the prefix foo is mapped to (which might even change  within  the
       document, resulting  in unexpected results). In order to make prefixes in XPath node tests
       actually map  to a real URI, you need to enable that via a call to the set_namespace
       method of your "XML::XPath" object.

   clear_namespaces()
       Clears all previously set namespace mappings.

   $XML::XPath::Namespaces
       Set this to 0  if you don't want namespace processing to occur. This will make everything
       a little (tiny) bit faster, but you'll suffer for it, probably.

Node Object Model

       See XML::XPath::Node, XML::XPath::Node::Element, XML::XPath::Node::Text,
       XML::XPath::Node::Comment, XML::XPath::Node::Attribute, XML::XPath::Node::Namespace, and
       XML::XPath::Node::PI.

On Garbage Collection

       XPath nodes  work in a special way that allows circular references, and yet still lets
       Perl's reference counting garbage collector to clean up the nodes after use.  This should
       be  totally  transparent to the user, with one caveat: If you free your tree before
       letting go of a sub-tree,consider that playing with fire and you may get burned. What does
       this mean to the average user?  Not much. Provided you don't free (or let go out of scope)
       either the tree you passed to XML::XPath->new, or if you didn't  pass a tree, and passed a
       filename or IO-ref, then provided you don't  let the XML::XPath object go out of scope
       before you let results of find() and its  friends  go out of scope, then you'll be fine.
       Even if you do let the tree go out of scope before results, you'll probably still be fine.
       The only case where  you  may  get  stung is when the last part of your path/query is
       either an ancestor or parent axis. In that case the worst that will happen is you'll end
       up with  a  circular  reference that won't get cleared until interpreter destruction
       time.You can get around that by explicitly calling $node->DESTROY on each of your result
       nodes, if you really need to do that.

       Mail me direct if that's not clear. Note that it's not doom and gloom. It's by no means
       perfect,but the worst that will happen is a long running process could leak memory. Most
       long  running  processes  will  therefore  be able to explicitly be careful not to free
       the tree (or XML::XPath object) before freeing results.AxKit, an application  that  uses
       XML::XPath,  does  this  and I didn't have to make any changes to the code - it's already
       sensible programming.

       If you really don't want all this to happen, then set the variable $XML::XPath::SafeMode,
       and call $xp->cleanup() on the XML::XPath object when you're finished, or $tree->dispose()
       if you have a tree instead.

Example

       Please see the test files in t/ for examples on how to use XPath.

AUTHOR

       Original author Matt Sergeant, "<matt at sergeant.org>"

       Currently maintained by Mohammad S Anwar, "<mohammad.anwar at yahoo.com>"

SEE ALSO

       XML::XPath::Literal, XML::XPath::Boolean, XML::XPath::Number, XML::XPath::XMLParser,
       XML::XPath::NodeSet, XML::XPath::PerlSAX, XML::XPath::Builder.

LICENSE AND COPYRIGHT

       This module is  copyright  2000 AxKit.com Ltd. This is free software, and as such comes
       with NO WARRANTY. No dates are used in this module. You may distribute this module under
       the terms  of either the Gnu GPL,  or the Artistic License (the same terms as Perl
       itself).

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