NAME

       XML::SemanticDiff - Perl extension for comparing XML documents.

SYNOPSIS

         use XML::SemanticDiff;
         my $diff = XML::SemanticDiff->new();

         foreach my $change ($diff->compare($file, $file2)) {
             print "$change->{message} in context $change->{context}\n";
         }

         # or, if you want line numbers:

         my $diff = XML::SemanticDiff->new(keeplinenums => 1);

         foreach my $change ($diff->compare($file, $file2)) {
             print "$change->{message} (between lines $change->{startline} and $change->{endline})\n";
         }

DESCRIPTION

       XML::SematicDiff provides a way to compare the contents and structure of two XML
       documents. By default, it returns a list of hashrefs where each hashref describes a single
       difference between the two docs.

METHODS

   $obj->new([%options])
       Ye olde object constructor.

       The new() method recognizes the following options:

       •   keeplinenums

           When this option is enabled XML::SemanticDiff will add the 'startline' and 'endline'
           properties (containing the line numbers for the reported element's start tag and end
           tag) to each warning. For attribute events these numbers reflect the start and end
           tags of the element which contains that attribute.

       •   keepdata

           When this option is enabled XML::SemanticDiff will add the 'old_value' and 'new_value'
           properties to each warning. These properties contain, surprisingly, the old and new
           values for the element or attribute being reported.

           In the case of missing elements or attributes (those in the first document, not in the
           second) only the 'old_value' property will be defined. Similarly, in the case of rogue
           elements or attributes (those in the second document but not in the first) only the
           'new_value' property will be defined.

           Note that using this option will greatly increase the amount of memory used by your
           application.

       •   diffhandler

           Taking a blessed object as it's sole argument, this option provides a way to hook the
           basic semantic diff engine into your own custom handler class.

           Please see the section on 'CUSTOM HANDLERS' below.

       •   ignorexpath

           This option takes array of strings as argument. Strings are interpreted as simple
           xpath expressions. Nodes matching these expressions are ignored during comparison. All
           xpath expressions should be absolute (start with '/').

           Current implementation ignores namespaces during comparison.

   @results = $differ->compare($xml1, $xml2)
       Compares the XMLs $xml1 and $xml2 . $xml1 and $xml2 can be:

       •   filenames

           This will be considered if it is a string that does not contain newlines and exists in
           the filesystem.

       •   the XML text itself.

           This will be considered if it's any kind of string.

       •   the results of read_xml(). (see below)

           This will be considered if it's a hash reference.

   my $doc = read_xml($xml_location)
       This will read the XML, process it for comparison and return it. See compare() for how it
       is determined.

CUSTOM HANDLERS

       Internally, XML::SemanticDiff uses an event-based model somewhat reminiscent of SAX where
       the various 'semantic diff events' are handed off to a separate handler class to cope with
       the details. For most general cases where the user only cares about reporting the
       differences between two docs, the default handler, XML::SemanticDiff::BasicHandler, will
       probably suffice. However, it is often desirable to add side-effects to the diff process
       (updating datastores, widget callbacks, etc.) and a custom handler allows you to be
       creative with what to do about differences between two XML documents and how those
       differences are reported back to the application through the compare() method.

HANDLER METHODS

       The following is a list of handler methods that can be used for your custom diff-handler
       class.

   init($self, $diff_obj)
       The "init" method is called immediately before the the two document HASHes are compared.
       The blessed XML::SemanticDiff object is passed as the sole argument, so any values that
       you wish to pass from your application to your custom handler can safely be added to the
       call to XML::SemanticDiff's constructor method.

   rogue_element($self, $element_name, $todoc_element_properties)
       The "rogue_element" method handles those cases where a given element exists in the to-file
       but not in the from-file.

   missing_element($self, $element_name, $fromdoc_element_properties)
       The "missing_element" method handles those cases where a given element exists in the from-
       file but not in the to-file.

   element_value($self, $element, $to_element_properties, $fromdoc_element_properties)
       The "element_value" method handles those cases where the text data differs between two
       elements that have the same name, namespace URI, and are at the same location in the
       document tree. Note that all whitespace is normalized and the text from mixed-content
       elements (those containing both text and child elements mixed together) is aggregated down
       to a single value.

   namespace_uri($self, $element, $todoc_element_properties, $fromdoc_element_properties)
       The "namespace_uri" method handles case where the XML namespace URI differs between a
       given element in the two documents. Note that the namespace URI is checked, not the
       element prefixes since <foo:element/> <bar:element/> and <element/> are all considered
       equivalent as long as they are bound to the same namespace URI.

   rogue_attribute($self, $attr_name, $element, $todoc_element_properties)
       The "rogue_attribute" method handles those cases where an attribute exists in a given
       element the to-file but not in the from-file.

   missing_attribute($self, $attr_name, $element, $todoc_element_properties,
       $fromdoc_element_properties)
       The "missing_attribute" method handles those cases where an attribute exists in a given
       element exists in the from-file but not in the to-file.

   attribute_value($self, $attr_name, $element, $todoc_element_properties,
       $fromdoc_element_properties)
       The "attribute_value" method handles those cases where the value of an attribute varies
       between the same element in both documents.

   final($self, $diff_obj)
       The "final" method is called immediately after the two document HASHes are compared. Like
       the "init" handler, it is passed a copy of the XML::SemanticDiff object as it's sole
       argument.

       Note that if a given method is not implemented in your custom handler class,
       XML::SemanticDiff will not complain; but it means that all of those events will be
       silently ignored. Consider yourself warned.

AUTHOR

       Originally by Kip Hampton, khampton@totalcinema.com .

       Further Maintained by Shlomi Fish, shlomif@iglu.org.il .

COPYRIGHT

       Copyright (c) 2000 Kip Hampton. All rights reserved. This program is free software; you
       can redistribute it and/or modify it under the same terms as Perl itself.

       Shlomi Fish hereby disclaims any implicit or explicit copyrights on this software.

LICENSE

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

SEE ALSO

       perl(1).