/[cvs]/nfo/perl/libs/XML/XUpdate/XSLT.pm
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revision 1.1 by joko, Wed Apr 30 02:36:32 2003 UTC revision 1.7 by joko, Tue May 13 09:32:22 2003 UTC
# Line 7  Line 7 
7  #    $Id$  #    $Id$
8  #  #
9  #    $Log$  #    $Log$
10    #    Revision 1.7  2003/05/13 09:32:22  joko
11    #    minor update to pod
12    #
13    #    Revision 1.6  2003/05/07 03:11:28  joko
14    #    updated pod: new section "References", added item to "Todo" section
15    #
16    #    Revision 1.5  2003/05/06 14:24:06  joko
17    #    doesn't use Carp any more
18    #    updated pod
19    #    attempt to rewrite xml to make it more human readable using helper modules from CPAN (node indentation, etc.)
20    #
21    #    Revision 1.4  2003/05/01 23:40:32  joko
22    #    minor update: commented debugging part
23    #
24    #    Revision 1.3  2003/05/01 20:11:49  joko
25    #    * added pod from xupdate.pl
26    #    - extracted xml to external files
27    #
28  #    Revision 1.1  2003/04/30 02:36:32  joko  #    Revision 1.1  2003/04/30 02:36:32  joko
29  #    initial commit  #    initial commit
30  #  #
31  #  #
32  ###############################################################################  ###############################################################################
33    
34    =pod
35    
36    
37  =head1 NAME  =head1 NAME
38    
39  XML::XUpdate::XSLT - A perl module for updating xml documents using XUpdate via XSLT.    XML::XUpdate::XSLT - A perl module for updating xml documents using XUpdate via XSLT.
40    
41    
42    =head3 Overview
43    
44      This is not the same xupdate currently available from CPAN at
45      http://search.cpan.org/author/PAJAS/XML-XUpdate-LibXML-0.4.0/xupdate .
46      
47      Its intention - however - is identical:
48      xupdate - Process XUpdate commands against an XML document.
49    
50    
51    =head4 Their implementations differ:
52    
53        1. xupdate (by Petr Pajas) uses ...
54        XML::XUpdate::LibXML - Simple implementation of XUpdate format
55        
56        ... which is based on XML::LibXML which in turn is:
57        [...]
58        This module is an interface to the gnome libxml2 DOM parser (no SAX parser support yet),
59        and the DOM tree. It also provides an XML::XPath-like findnodes() interface, providing
60        access to the XPath API in libxml2.
61        [...]
62    
63        2. This xupdate attempts to implement the XUpdate specs using XSLT only.
64        
65    
66    =head4 Yet another xupdate - facts in short:
67    
68      S: It would be nice to have a pure perl thingy which does (almost) the same stuff....
69      
70      Q: Can we achieve compliance with its (XML::XUpdate::LibXML) API? (or just a subset ....)
71      
72      Q: Can we achieve the processing using CPAN's XML::XSLT?
73      S: Proposal: XML::XUpdate::XSLT!?
74      
75      Q: Can we mimic/use the interface of the - already established - 'xupdate' program???
76      
77      Q: Should we follow the CRUD path first?
78          (CRUD is the acronym for the datastore action primitives: Create, Retrieve, Update, Delete)
79      S?: Proposal: XML::XUpdate::XSLT::API uses XML::XUpdate::XSLT::CRUD
80    
81    
82    =head3 References
83    
84        - XUpdate:
85          Requirements: http://www.xmldb.org/xupdate/xupdate-req.html
86          Working Draft: http://www.xmldb.org/xupdate/xupdate-wd.html
87        - XML API:
88        - XML::XUpdate::LibXML: http://search.cpan.org/author/PAJAS/XML-XUpdate-LibXML-0.4.0/lib/XML/XUpdate/LibXML.pm
89        - XSL / XSLT:
90          http://www.w3.org/TR/xslt
91          http://www.xsl-rp.de/
92          http://xml.klute-thiemann.de/w3c-de/REC-xslt-20020318/
93          http://xmlxslt.sourceforge.net/
94        - misc pointers:
95          "Re: Modify XML documents": http://aspn.activestate.com/ASPN/Mail/Message/perl-xml/1265431
96          XSL Extensions: http://xmlsoft.org/XSLT/extensions.html
97          EXSLT: http://www.exslt.org/set/functions/difference/index.html
98          "how to insert element at required position in document tree?": http://p2p.wrox.com/archive/xslt/2001-06/98.asp
99          XML APIs for Databases: http://www.javaworld.com/javaworld/jw-01-2000/jw-01-dbxml.html
100    
101    
102    =head3 Todo
103    
104      o What about proper encoding? (ISO-8859-1 or UTF-8)
105      o Is it possible to create the required "xsl_template.xml" at runtime via XSL itself?
106      o Cache contents of external files (*.xml). Performance!
107      o Can exception / error-code handling be improved somehow?
108          Esp.: It would be interesting, if the XUpdate payload actually could be applied, or not...
109      o Conditional processing: <xupdate:if>, etc.
110      
111    
112  =cut  =cut
113    
# Line 27  package XML::XUpdate::XSLT; Line 119  package XML::XUpdate::XSLT;
119  use strict;  use strict;
120  use warnings;  use warnings;
121    
 use XML::XSLT 0.41;  
 use Carp;  
122  use Data::Dumper;  use Data::Dumper;
123    use File::Basename;
124    use XML::XSLT 0.41;
125    use XML::XUpdate::Rewrite;
126    
127  # Namespace constants  # Namespace constants
128    
# Line 37  use constant NS_XUPDATE         => 'http Line 130  use constant NS_XUPDATE         => 'http
130    
131  use vars qw ( $VERSION );  use vars qw ( $VERSION );
132    
133  $VERSION = '0.02';  $VERSION = '0.01';
134    
135    
136  ######################################################################  ######################################################################
# Line 48  sub new { Line 141  sub new {
141    my $self = bless {}, $class;    my $self = bless {}, $class;
142    my $args = $self->__parse_args(@_);    my $args = $self->__parse_args(@_);
143        
144    $self->__init_default_macros();    $self->{DEBUG} = $args->{debug};
145      $self->{WARNINGS} = $args->{warnings};
146    
147  #=pod    $self->__init_default_stylesheets();
   $self->{XSLT_ENGINE} = XML::XSLT->new(  
     Source => $self->get_macro("xupdate2xsl"),  
     debug => $args->{debug},  
     warnings => $args->{warnings}  
   );  
 #=cut  
148    
   #print Dumper($self);  
149    return $self;    return $self;
150    
151  }  }
152    
153  sub get_macro {  sub get_stylesheet {
154    my $self = shift;    my $self = shift;
155    my $name = shift;    my $name = shift;
156    return $self->{MACROS}->{$name};    return $self->{XML}->{xsl}->{$name};
157    }
158    
159    sub set_stylesheet {
160      my $self = shift;
161      my $name = shift;
162      my $xml = shift;
163      my $options = shift;
164      if ($options->{encap}) {
165        my $template = $self->__slurp_file("xsl_template.xml");
166        # FIXME! What about the quirky? Is there a better one?
167        $template =~ s!<xsl:quirky_placeholder />!$xml!;
168        $xml = $template;
169      }
170      $self->{XML}->{xsl}->{$name} = $xml;
171  }  }
172    
173  sub open_document {  sub open_document {
# Line 85  sub open_xupdate { Line 186  sub open_xupdate {
186    
187  sub process {  sub process {
188    my $self = shift;    my $self = shift;
189    # first, translate xupdate to xsl    $self->_calculate();
190    $self->{XSLT_ENGINE}->open_xml( $self->{XML}->{xupdate} );    $self->_apply();
   $self->{XSLT_ENGINE}->process();  
   $self->{XML}->{XSL} = $self->{XSLT_ENGINE}->toString();  
191  }  }
192    
193  sub toString {  # First, translate the xupdate payload to xsl.
194    # FIXME: do DOM only! (don't use "->toString")
195    sub _calculate {
196    my $self = shift;    my $self = shift;
197    return $self->{XML}->{XSL};    $self->{XSLT_ENGINE_PREP} = XML::XSLT->new(
198        Source => $self->get_stylesheet("xupdate2xsl"),
199        debug => $self->{DEBUG},
200        warnings => $self->{WARNINGS}
201      );
202      $self->{XSLT_ENGINE_PREP}->open_xml( $self->{XML}->{xupdate} );
203      $self->{XSLT_ENGINE_PREP}->process();
204      $self->set_stylesheet( "_worker", $self->{XSLT_ENGINE_PREP}->toString(), { encap => 1 } );
205  }  }
206    
207    # After that, use this worker xsl to actually apply the changes to the original document.
208    # FIXME: do DOM only!
209    sub _apply {
210      my $self = shift;
211      
212      # debug - print the calculated xsl on STDERR
213      print STDERR $self->get_stylesheet("_worker"), "\n";
214      
215      #return;
216      $self->{XSLT_ENGINE_LIVE} = XML::XSLT->new(
217        Source => $self->get_stylesheet("_worker"),
218        debug => $self->{DEBUG},
219        warnings => $self->{WARNINGS}
220      );
221      $self->{XSLT_ENGINE_LIVE}->open_xml( $self->{XML}->{document} );
222      $self->{XSLT_ENGINE_LIVE}->process();
223      $self->{XML}->{result} = $self->{XSLT_ENGINE_LIVE}->toString();
224    }  
225      
226    sub toString {
227      my $self = shift;
228      
229      # use rest of argument list as hash of option values
230      my $options = {@_};
231      
232      # short circuit - just return what we have - don't modify anything
233      return $self->{XML}->{result} unless $options and $options->{rewrite};
234      
235      # Rewrite the xml document with certain engine to desired style.
236      # 'engine' defaults to "XMLParser" if not specified.
237      my $rewrite = XML::XUpdate::Rewrite->new( style => $options->{mode}, engine => $options->{using} );
238      $rewrite->set_document( $self->{XML}->{result} );
239      # TODO: Implement a configurable fallback here to return the un-rewritten payload if desired.
240      $rewrite->process() or die(__PACKAGE__ . ": Error while rewriting XML document.");
241      return $rewrite->get_document();
242    }
243    
244    
245  ######################################################################  ######################################################################
246  # AUXILIARY METHODS  # AUXILIARY METHODS
247    
248  # Argument parsing with backwards compatibility.  # Argument list parsing.
249    # ... from XML::XUpdate::LibXML (w/o backwards compatibility hook).
250    # Could this make up a Class::AutoFill::__read_arglist which transparently
251    # makes object attributes from constructor arguments in a configurable way?
252  sub __parse_args {  sub __parse_args {
253    my $self = shift;    my $self = shift;
254    my %args;    my %args;
255    
256    if(@_ % 2 ) {    if ( @_ % 2 ) {
257      $args{dummy} = shift;      $args{dummy} = shift;
258      %args = (%args, @_);      %args = (%args, @_);
259    } else {    } else {
# Line 116  sub __parse_args { Line 264  sub __parse_args {
264  }  }
265    
266    
267  sub __init_default_macros {  sub __init_default_stylesheets {
268    my $self = shift;    my $self = shift;
269    $self->{MACROS}->{xupdate2xsl} = qq(<?xml version="1.0" encoding="ISO-8859-1"?>    if (my $payload = $self->__slurp_file("xupdate2xsl.xml")) {
270          $self->{XML}->{xsl}->{xupdate2xsl} = $payload;
271    <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">    }
272    }
273    
274    sub __slurp_file {
275      my $self = shift;
276      my $filename = shift;
277        
278        <!--    # does file exist?
279        Purpose of this XML Stylesheet is to implement a set of templates    if (! -e $filename) {
280        to translate XUpdate lingo into an intermediate xslt stylesheet      $filename = dirname(__FILE__) . "/$filename";
281        which actually performs the update to the original xml document.      if (! -e $filename) {
282        -->        die("File $filename does not exist.");
283              }
284        <xsl:output method="xml" />    }
     
       <!-- 1. This is the passthru logic (copy all untouched nodes). -->  
       <xsl:template name="passthru"><xsl:copy><xsl:apply-templates /></xsl:copy></xsl:template>  
       <!-- activate this -->  
       <xsl:template match="*"><xsl:call-template name="passthru" /></xsl:template>  
       <!-- override some builtin rules: see http://www.w3.org/TR/xslt#built-in-rule -->  
       <xsl:template match="comment()"><xsl:call-template name="passthru" /></xsl:template>  
     
       <!-- 2. This is the translation part: XUpdate becomes XSLT -->  
         
       <!-- This node "encapsulates" common infrastructure. -->  
       <xsl:template match="xupdate:modifications">  
     
           <!-- 1. This is the passthru logic (copy all untouched nodes). -->  
           <!-- in fact this is the xsl from above translated to be able to be generated by xsl itself! -->  
               <xsl:comment> 1. passthru logic </xsl:comment>  
               <xsl:element name="xsl:template">  
                   <xsl:attribute name="name">passthru</xsl:attribute>  
                   <xsl:element name="xsl:copy"><xsl:element name="xsl:apply-templates" /></xsl:element>  
               </xsl:element>  
               <xsl:element name="xsl:template">  
                   <xsl:attribute name="match">*</xsl:attribute>  
                   <xsl:element name="xsl:call-template"><xsl:attribute name="name">passthru</xsl:attribute></xsl:element>  
               </xsl:element>  
               <xsl:element name="xsl:template">  
                   <xsl:attribute name="match">comment()</xsl:attribute>  
                   <xsl:element name="xsl:call-template"><xsl:attribute name="name">passthru</xsl:attribute></xsl:element>  
               </xsl:element>  
     
           <!-- continue with all inline nodes -->  
               <xsl:apply-templates />  
     
       </xsl:template>  
     
       <!-- This node "encapsulates" infrastructure for handling the directives. -->  
       <xsl:template match="xupdate:insert-after">  
           <xsl:comment> 2. context finder </xsl:comment>  
           <xsl:apply-templates />  
       </xsl:template>  
     
       <!-- This node passes through all attributes and childnodes rewriting the tagname only. -->  
       <xsl:template match="xupdate:element">  
           <xsl:comment> 3. rewrite / vivify elements/attributes </xsl:comment>  
           <xsl:element name="xsl:element">  
               <xsl:copy-of select="@*"/>  
               <xsl:apply-templates />  
           </xsl:element>  
       </xsl:template>  
     
       <!-- This node passes through all attributes and childnodes rewriting the tagname only. -->  
       <xsl:template match="xupdate:attribute">  
           <xsl:element name="xsl:attribute">  
               <xsl:copy-of select="@*"/>  
               <xsl:apply-templates />  
           </xsl:element>  
       </xsl:template>  
     
   </xsl:stylesheet>  
285        
286    );    open(FH, "<" . $filename);
287      my @lines = <FH>;
288      my $content = join("", @lines);
289      close(FH);
290      return $content;
291  }  }
292    
293  1;  1;
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