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XML::XPath(3pm)       User Contributed Perl Documentation      XML::XPath(3pm)

NAME
       XML::XPath - Parse and evaluate XPath statements.

VERSION
       Version 1.48

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.

       Currently, it supports XPath 1.0 with a small number of XPath 2.0
       functions. See XML::XPath::Function for the complete list of predefined
       functions.

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::Function, 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).

       For support, please subscribe to the Perl-XML
       <http://listserv.activestate.com/mailman/listinfo/perl-xml> mailing
       list at the URL

perl v5.34.0                      2022-08-13                   XML::XPath(3pm)

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