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XML::XPathEngine(3pm) User Contributed Perl DocumentationXML::XPathEngine(3pm)

NAME
       XML::XPathEngine - a re-usable XPath engine for DOM-like trees

DESCRIPTION
       This module provides an XPath engine, that can be re-used by other
       module/classes that implement trees.

       In order to use the XPath engine, nodes in the user module need to
       mimick DOM nodes. The degree of similitude between the user tree and a
       DOM dictates how much of the XPath features can be used. A module
       implementing all of the DOM should be able to use this module very
       easily (you might need to add the cmp method on nodes in order to get
       ordered result sets).

       This code is a more or less direct copy of the XML::XPath module by
       Matt Sergeant. I only removed the XML processing part to remove the
       dependency on XML::Parser, applied a couple of patches, renamed a whole
       lot of methods to make Pod::Coverage happy, and changed the docs.

       The article eXtending XML XPath,
       http://www.xmltwig.com/article/extending_xml_xpath/ should give authors
       who want to use this module enough background to do so.

       Otherwise, my email is below ;--)

       WARNING: while the underlying code is rather solid, this module mostly
       lacks docs.  As they say, "patches welcome"...

SYNOPSIS
	   use XML::XPathEngine;

	   my $tree= my_tree->new( ...);
	   my $xp = XML::XPathEngine->new();

	   my @nodeset = $xp->find('/root/kid/grandkid[1]', $tree); # find all first grankids

	   package XML::MyTree;

	   # needs to provide DOM methods

DETAILS
API
       XML::XPathEngine will provide the following methods:

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

   findnodes_as_string ($path, $context)
       Returns the nodes found as a single string. The result is not
       guaranteed to be valid XML though (it could for example be just text if
       the query returns attribute values).

   findnodes_as_strings ($path, $context)
       Returns the nodes found as a list of strings, one per node found.

   findvalue ($path, $context)
       Returns the result as a string (the concatenation of the values of the
       result nodes).

   findvalues($path, $context)
       Returns the values of the result nodes as a list of strings.

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

   matches($node, $path, $context)
       Returns true if the node matches the path.

   find ($path, $context)
       The find function takes an XPath expression (a string) and returns
       either a XML::XPathEngine::NodeSet object containing the nodes it found
       (or empty if no nodes matched the path), or one of
       XML::XPathEngine::Literal (a string), XML::XPathEngine::Number, or
       XML::XPathEngine::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::XPathEngine::NodeSet.

   getNodeText ($path)
       Returns the text string for a particular node. Returns a string, or
       undef if the node doesn't exist.

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

       Normally in XML::XPathEngine the prefixes in XPath node tests 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::XPathEngine object.

   clear_namespaces ()
       Clears all previously set namespace mappings.

   get_namespace ($prefix, $node)
       Returns the uri associated to the prefix for the node (mostly for
       internal usage)

   set_strict_namespaces ($strict)
       By default, for historical as well as convenience reasons,
       XML::XPathEngine has a slightly non-standard way of dealing with the
       default namespace.

       If you search for "//tag" it will return elements "tag". As far as I
       understand it, if the document has a default namespace, this should not
       return anything.	 You would have to first do a "set_namespace", and
       then search using the namespace.

       Passing a true value to "set_strict_namespaces" will activate this
       behaviour, passing a false value will return it to its default
       behaviour.

   set_var ($var. $val)
       Sets an XPath variable (that can be used in queries as $var)

   get_var ($var)
       Returns the value of the XPath variable (mostly for internal usage)

   $XML::XPathEngine::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
       Nodes need to provide the same API as nodes in XML::XPath (at least the
       access API, not the tree manipulation one).

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

XPath extension
       The module supports the XPath recommendation to the same extend as
       XML::XPath (that is, rather completely).

       It includes a perl-specific extension: direct support for regular
       expressions.

       You can use the usual (in Perl!) "=~" and "!~" operators. Regular
       expressions are / delimited (no other delimiter is accepted, \ inside
       regexp must be backslashed), the "imsx" modifiers can be used.

	 $xp->findnodes( '//@att[.=~ /^v.$/]'); # returns the list of attributes att
						# whose value matches ^v.$

SEE ALSO
       XML::XPath

       HTML::TreeBuilder::XPath, XML::Twig::XPath for exemples of using this
       module

       Tree::XPathEngine for a similar module for non-XML trees.

       <http://www.xmltwig.com/article/extending_xml_xpath/> for background
       information. The last section of the article summarizes how to reuse
       XML::XPath.  As XML::XPathEngine offers the same API it should help you

AUTHOR
       Michel Rodriguez, "<mirod@cpan.org>" Most code comes directly from
       XML::XPath, by Matt Sergeant.

BUGS
       Please report any bugs or feature requests to
       "bug-tree-xpathengine@rt.cpan.org", or through the web interface at
       <http://rt.cpan.org/NoAuth/ReportBug.html?Queue=XML-XPathEngine>.  I
       will be notified, and then you'll automatically be notified of progress
       on your bug as I make changes.

ACKNOWLEDGEMENTS
COPYRIGHT & LICENSE
       XML::XPath Copyright 2000 AxKit.com Ltd.	 Copyright 2006 Michel
       Rodriguez, All Rights Reserved.

       This program is free software; you can redistribute it and/or modify it
       under the same terms as Perl itself.

perl v5.10.0			  2009-08-09		 XML::XPathEngine(3pm)
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