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############################################################################## |
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# |
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# Perl module: XML::XUpdate::XSLT |
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# |
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# By Andreas Motl, andreas.motl@ilo.de |
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# |
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# $Id: XSLT.pm,v 1.7 2003/05/13 09:32:22 joko Exp $ |
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# |
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# $Log: XSLT.pm,v $ |
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# Revision 1.7 2003/05/13 09:32:22 joko |
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# minor update to pod |
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# |
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# Revision 1.6 2003/05/07 03:11:28 joko |
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# updated pod: new section "References", added item to "Todo" section |
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# |
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# Revision 1.5 2003/05/06 14:24:06 joko |
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# doesn't use Carp any more |
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# updated pod |
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# attempt to rewrite xml to make it more human readable using helper modules from CPAN (node indentation, etc.) |
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# |
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# Revision 1.4 2003/05/01 23:40:32 joko |
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# minor update: commented debugging part |
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# |
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# Revision 1.3 2003/05/01 20:11:49 joko |
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# * added pod from xupdate.pl |
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# - extracted xml to external files |
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# |
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# Revision 1.1 2003/04/30 02:36:32 joko |
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# initial commit |
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# |
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# |
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############################################################################### |
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|
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=pod |
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=head1 NAME |
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XML::XUpdate::XSLT - A perl module for updating xml documents using XUpdate via XSLT. |
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=head3 Overview |
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This is not the same xupdate currently available from CPAN at |
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http://search.cpan.org/author/PAJAS/XML-XUpdate-LibXML-0.4.0/xupdate . |
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|
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Its intention - however - is identical: |
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xupdate - Process XUpdate commands against an XML document. |
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=head4 Their implementations differ: |
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1. xupdate (by Petr Pajas) uses ... |
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XML::XUpdate::LibXML - Simple implementation of XUpdate format |
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... which is based on XML::LibXML which in turn is: |
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[...] |
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This module is an interface to the gnome libxml2 DOM parser (no SAX parser support yet), |
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and the DOM tree. It also provides an XML::XPath-like findnodes() interface, providing |
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access to the XPath API in libxml2. |
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[...] |
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|
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2. This xupdate attempts to implement the XUpdate specs using XSLT only. |
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=head4 Yet another xupdate - facts in short: |
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S: It would be nice to have a pure perl thingy which does (almost) the same stuff.... |
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Q: Can we achieve compliance with its (XML::XUpdate::LibXML) API? (or just a subset ....) |
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Q: Can we achieve the processing using CPAN's XML::XSLT? |
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S: Proposal: XML::XUpdate::XSLT!? |
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Q: Can we mimic/use the interface of the - already established - 'xupdate' program??? |
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Q: Should we follow the CRUD path first? |
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(CRUD is the acronym for the datastore action primitives: Create, Retrieve, Update, Delete) |
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S?: Proposal: XML::XUpdate::XSLT::API uses XML::XUpdate::XSLT::CRUD |
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|
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=head3 References |
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|
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- XUpdate: |
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Requirements: http://www.xmldb.org/xupdate/xupdate-req.html |
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Working Draft: http://www.xmldb.org/xupdate/xupdate-wd.html |
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- XML API: |
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- XML::XUpdate::LibXML: http://search.cpan.org/author/PAJAS/XML-XUpdate-LibXML-0.4.0/lib/XML/XUpdate/LibXML.pm |
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- XSL / XSLT: |
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http://www.w3.org/TR/xslt |
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http://www.xsl-rp.de/ |
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http://xml.klute-thiemann.de/w3c-de/REC-xslt-20020318/ |
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http://xmlxslt.sourceforge.net/ |
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- misc pointers: |
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"Re: Modify XML documents": http://aspn.activestate.com/ASPN/Mail/Message/perl-xml/1265431 |
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XSL Extensions: http://xmlsoft.org/XSLT/extensions.html |
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EXSLT: http://www.exslt.org/set/functions/difference/index.html |
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"how to insert element at required position in document tree?": http://p2p.wrox.com/archive/xslt/2001-06/98.asp |
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XML APIs for Databases: http://www.javaworld.com/javaworld/jw-01-2000/jw-01-dbxml.html |
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=head3 Todo |
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o What about proper encoding? (ISO-8859-1 or UTF-8) |
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o Is it possible to create the required "xsl_template.xml" at runtime via XSL itself? |
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o Cache contents of external files (*.xml). Performance! |
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o Can exception / error-code handling be improved somehow? |
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Esp.: It would be interesting, if the XUpdate payload actually could be applied, or not... |
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o Conditional processing: <xupdate:if>, etc. |
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=cut |
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###################################################################### |
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package XML::XUpdate::XSLT; |
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###################################################################### |
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use strict; |
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use warnings; |
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use Data::Dumper; |
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use File::Basename; |
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use XML::XSLT 0.41; |
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use XML::XUpdate::Rewrite; |
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# Namespace constants |
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use constant NS_XUPDATE => 'http://www.xmldb.org/xupdate'; |
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use vars qw ( $VERSION ); |
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$VERSION = '0.01'; |
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###################################################################### |
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# PUBLIC DEFINITIONS |
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sub new { |
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my $class = shift; |
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my $self = bless {}, $class; |
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my $args = $self->__parse_args(@_); |
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$self->{DEBUG} = $args->{debug}; |
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$self->{WARNINGS} = $args->{warnings}; |
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$self->__init_default_stylesheets(); |
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return $self; |
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} |
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sub get_stylesheet { |
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my $self = shift; |
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my $name = shift; |
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return $self->{XML}->{xsl}->{$name}; |
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} |
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sub set_stylesheet { |
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my $self = shift; |
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my $name = shift; |
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my $xml = shift; |
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my $options = shift; |
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if ($options->{encap}) { |
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my $template = $self->__slurp_file("xsl_template.xml"); |
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# FIXME! What about the quirky? Is there a better one? |
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$template =~ s!<xsl:quirky_placeholder />!$xml!; |
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$xml = $template; |
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} |
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$self->{XML}->{xsl}->{$name} = $xml; |
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} |
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sub open_document { |
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my $self = shift; |
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my $xml = shift; |
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# FIXME: check for filename, filehandle and URL (etc.) |
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$self->{XML}->{document} = $xml; |
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} |
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sub open_xupdate { |
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my $self = shift; |
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my $xml = shift; |
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# FIXME: check for filename, filehandle and URL (etc.) |
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$self->{XML}->{xupdate} = $xml; |
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} |
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sub process { |
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my $self = shift; |
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$self->_calculate(); |
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$self->_apply(); |
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} |
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# First, translate the xupdate payload to xsl. |
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# FIXME: do DOM only! (don't use "->toString") |
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sub _calculate { |
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my $self = shift; |
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$self->{XSLT_ENGINE_PREP} = XML::XSLT->new( |
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Source => $self->get_stylesheet("xupdate2xsl"), |
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debug => $self->{DEBUG}, |
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warnings => $self->{WARNINGS} |
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); |
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$self->{XSLT_ENGINE_PREP}->open_xml( $self->{XML}->{xupdate} ); |
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$self->{XSLT_ENGINE_PREP}->process(); |
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$self->set_stylesheet( "_worker", $self->{XSLT_ENGINE_PREP}->toString(), { encap => 1 } ); |
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} |
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# After that, use this worker xsl to actually apply the changes to the original document. |
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# FIXME: do DOM only! |
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sub _apply { |
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my $self = shift; |
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# debug - print the calculated xsl on STDERR |
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print STDERR $self->get_stylesheet("_worker"), "\n" if $self->{DEBUG}; |
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#return; |
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$self->{XSLT_ENGINE_LIVE} = XML::XSLT->new( |
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Source => $self->get_stylesheet("_worker"), |
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debug => $self->{DEBUG}, |
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warnings => $self->{WARNINGS} |
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); |
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$self->{XSLT_ENGINE_LIVE}->open_xml( $self->{XML}->{document} ); |
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$self->{XSLT_ENGINE_LIVE}->process(); |
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$self->{XML}->{result} = $self->{XSLT_ENGINE_LIVE}->toString(); |
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} |
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sub toString { |
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my $self = shift; |
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# use rest of argument list as hash of option values |
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my $options = {@_}; |
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# short circuit - just return what we have - don't modify anything |
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return $self->{XML}->{result} unless $options and $options->{rewrite}; |
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# Rewrite the xml document with certain engine to desired style. |
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# 'engine' defaults to "XMLParser" if not specified. |
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my $rewrite = XML::XUpdate::Rewrite->new( style => $options->{mode}, engine => $options->{using} ); |
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$rewrite->set_document( $self->{XML}->{result} ); |
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# TODO: Implement a configurable fallback here to return the un-rewritten payload if desired. |
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$rewrite->process() or die(__PACKAGE__ . ": Error while rewriting XML document."); |
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return $rewrite->get_document(); |
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} |
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###################################################################### |
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# AUXILIARY METHODS |
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# Argument list parsing. |
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# ... from XML::XUpdate::LibXML (w/o backwards compatibility hook). |
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# Could this make up a Class::AutoFill::__read_arglist which transparently |
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# makes object attributes from constructor arguments in a configurable way? |
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sub __parse_args { |
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my $self = shift; |
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my %args; |
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if ( @_ % 2 ) { |
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$args{dummy} = shift; |
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%args = (%args, @_); |
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} else { |
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%args = @_; |
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} |
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return \%args; |
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} |
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sub __init_default_stylesheets { |
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my $self = shift; |
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if (my $payload = $self->__slurp_file("xupdate2xsl.xml")) { |
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$self->{XML}->{xsl}->{xupdate2xsl} = $payload; |
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} |
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} |
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sub __slurp_file { |
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my $self = shift; |
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my $filename = shift; |
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# does file exist? |
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if (! -e $filename) { |
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$filename = dirname(__FILE__) . "/$filename"; |
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if (! -e $filename) { |
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die("File $filename does not exist."); |
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} |
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} |
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open(FH, "<" . $filename); |
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my @lines = <FH>; |
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my $content = join("", @lines); |
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close(FH); |
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return $content; |
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} |
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1; |
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__END__ |
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