/[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 1.5 by joko, Tue May 6 14:24:06 2003 UTC
# Line 7  Line 7 
7  #    $Id$  #    $Id$
8  #  #
9  #    $Log$  #    $Log$
10    #    Revision 1.5  2003/05/06 14:24:06  joko
11    #    doesn't use Carp any more
12    #    updated pod
13    #    attempt to rewrite xml to make it more human readable using helper modules from CPAN (node indentation, etc.)
14    #
15    #    Revision 1.4  2003/05/01 23:40:32  joko
16    #    minor update: commented debugging part
17    #
18    #    Revision 1.3  2003/05/01 20:11:49  joko
19    #    * added pod from xupdate.pl
20    #    - extracted xml to external files
21    #
22  #    Revision 1.1  2003/04/30 02:36:32  joko  #    Revision 1.1  2003/04/30 02:36:32  joko
23  #    initial commit  #    initial commit
24  #  #
25  #  #
26  ###############################################################################  ###############################################################################
27    
28    =pod
29    
30    
31  =head1 NAME  =head1 NAME
32    
33  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.
34    
35    
36    =head3 Overview
37    
38      This is not the same xupdate currently available from CPAN at
39      http://search.cpan.org/author/PAJAS/XML-XUpdate-LibXML-0.4.0/xupdate .
40      
41      Its intention - however - is identical:
42      xupdate - Process XUpdate commands against an XML document.
43    
44    
45    =head3 Their implementations differ:
46    
47        1. xupdate (by Petr Pajas) uses ...
48        XML::XUpdate::LibXML - Simple implementation of XUpdate format
49        
50        ... which is based on XML::LibXML which in turn is:
51        [...]
52        This module is an interface to the gnome libxml2 DOM parser (no SAX parser support yet),
53        and the DOM tree. It also provides an XML::XPath-like findnodes() interface, providing
54        access to the XPath API in libxml2.
55        [...]
56    
57        2. This xupdate attempts to implement the XUpdate specs using XSLT only.
58        
59    
60    =head3 Yet another xupdate - facts in short:
61    
62      S: It would be nice to have a pure perl thingy which does (almost) the same stuff....
63      
64      Q: Can we achieve compliance with its (XML::XUpdate::LibXML) API? (or just a subset ....)
65      
66      Q: Can we achieve the processing using CPAN's XML::XSLT?
67      S: Proposal: XML::XUpdate::XSLT!?
68      
69      Q: Can we mimic/use the interface of the - already established - 'xupdate' program???
70      
71      Q: Should we follow the CRUD path first?
72          (CRUD is the acronym for the datastore action primitives: Create, Retrieve, Update, Delete)
73      S?: Proposal: XML::XUpdate::XSLT::API uses XML::XUpdate::XSLT::CRUD
74    
75    
76    =head4 Todo
77    
78      o What about proper encoding? (ISO-8859-1 or UTF-8)
79      o Is it possible to create the required "xsl_template.xml" at runtime via XSL itself?
80      o Cache contents of external files (*.xml). Performance!
81      o Can exception / error-code handling be improved somehow?
82          Esp.: It would be interesting, if the XUpdate payload actually could be applied, or not...
83      
84    
85  =cut  =cut
86    
# Line 27  package XML::XUpdate::XSLT; Line 92  package XML::XUpdate::XSLT;
92  use strict;  use strict;
93  use warnings;  use warnings;
94    
 use XML::XSLT 0.41;  
 use Carp;  
95  use Data::Dumper;  use Data::Dumper;
96    use File::Basename;
97    use XML::XSLT 0.41;
98    use XML::XUpdate::Rewrite;
99    
100  # Namespace constants  # Namespace constants
101    
# Line 37  use constant NS_XUPDATE         => 'http Line 103  use constant NS_XUPDATE         => 'http
103    
104  use vars qw ( $VERSION );  use vars qw ( $VERSION );
105    
106  $VERSION = '0.02';  $VERSION = '0.01';
107    
108    
109  ######################################################################  ######################################################################
# Line 48  sub new { Line 114  sub new {
114    my $self = bless {}, $class;    my $self = bless {}, $class;
115    my $args = $self->__parse_args(@_);    my $args = $self->__parse_args(@_);
116        
117    $self->__init_default_macros();    $self->{DEBUG} = $args->{debug};
118      $self->{WARNINGS} = $args->{warnings};
119    
120  #=pod    $self->__init_default_stylesheets();
   $self->{XSLT_ENGINE} = XML::XSLT->new(  
     Source => $self->get_macro("xupdate2xsl"),  
     debug => $args->{debug},  
     warnings => $args->{warnings}  
   );  
 #=cut  
121    
   #print Dumper($self);  
122    return $self;    return $self;
123    
124  }  }
125    
126  sub get_macro {  sub get_stylesheet {
127    my $self = shift;    my $self = shift;
128    my $name = shift;    my $name = shift;
129    return $self->{MACROS}->{$name};    return $self->{XML}->{xsl}->{$name};
130    }
131    
132    sub set_stylesheet {
133      my $self = shift;
134      my $name = shift;
135      my $xml = shift;
136      my $options = shift;
137      if ($options->{encap}) {
138        my $template = $self->__slurp_file("xsl_template.xml");
139        # FIXME! What about the quirky? Is there a better one?
140        $template =~ s!<xsl:quirky_placeholder />!$xml!;
141        $xml = $template;
142      }
143      $self->{XML}->{xsl}->{$name} = $xml;
144  }  }
145    
146  sub open_document {  sub open_document {
# Line 79  sub open_document { Line 153  sub open_document {
153  sub open_xupdate {  sub open_xupdate {
154    my $self = shift;    my $self = shift;
155    my $xml = shift;    my $xml = shift;
156    # FIXME: check for filename, filehandle and URL (etc.)    # FIXME: check for filename, filehandle and U<RL (etc.)
157    $self->{XML}->{xupdate} = $xml;    $self->{XML}->{xupdate} = $xml;
158  }  }
159    
160  sub process {  sub process {
161    my $self = shift;    my $self = shift;
162    # first, translate xupdate to xsl    $self->_calculate();
163    $self->{XSLT_ENGINE}->open_xml( $self->{XML}->{xupdate} );    $self->_apply();
   $self->{XSLT_ENGINE}->process();  
   $self->{XML}->{XSL} = $self->{XSLT_ENGINE}->toString();  
164  }  }
165    
166  sub toString {  # First, translate the xupdate payload to xsl.
167    # FIXME: do DOM only! (don't use "->toString")
168    sub _calculate {
169    my $self = shift;    my $self = shift;
170    return $self->{XML}->{XSL};    $self->{XSLT_ENGINE_PREP} = XML::XSLT->new(
171        Source => $self->get_stylesheet("xupdate2xsl"),
172        debug => $self->{DEBUG},
173        warnings => $self->{WARNINGS}
174      );
175      $self->{XSLT_ENGINE_PREP}->open_xml( $self->{XML}->{xupdate} );
176      $self->{XSLT_ENGINE_PREP}->process();
177      $self->set_stylesheet( "_worker", $self->{XSLT_ENGINE_PREP}->toString(), { encap => 1 } );
178  }  }
179    
180    # After that, use this worker xsl to actually apply the changes to the original document.
181    # FIXME: do DOM only!
182    sub _apply {
183      my $self = shift;
184      
185      # debug - print the calculated xsl on STDERR
186      #print STDERR $self->get_stylesheet("_worker"), "\n";
187      
188      #return;
189      $self->{XSLT_ENGINE_LIVE} = XML::XSLT->new(
190        Source => $self->get_stylesheet("_worker"),
191        debug => $self->{DEBUG},
192        warnings => $self->{WARNINGS}
193      );
194      $self->{XSLT_ENGINE_LIVE}->open_xml( $self->{XML}->{document} );
195      $self->{XSLT_ENGINE_LIVE}->process();
196      $self->{XML}->{result} = $self->{XSLT_ENGINE_LIVE}->toString();
197    }  
198      
199    sub toString {
200      my $self = shift;
201      
202      # use rest of argument list as hash of option values
203      my $options = {@_};
204      
205      # short circuit - just return what we have - don't modify anything
206      return $self->{XML}->{result} unless $options and $options->{rewrite};
207      
208      # Rewrite the xml document with certain engine to desired style.
209      # 'engine' defaults to "XMLParser" if not specified.
210      my $rewrite = XML::XUpdate::Rewrite->new( style => $options->{mode}, engine => $options->{using} );
211      $rewrite->set_document( $self->{XML}->{result} );
212      # TODO: Implement a configurable fallback here to return the un-rewritten payload if desired.
213      $rewrite->process() or die(__PACKAGE__ . ": Error while rewriting XML document.");
214      return $rewrite->get_document();
215    }
216    
217    
218  ######################################################################  ######################################################################
219  # AUXILIARY METHODS  # AUXILIARY METHODS
220    
221  # Argument parsing with backwards compatibility.  # Argument list parsing.
222    # ... from XML::XUpdate::LibXML (w/o backwards compatibility hook).
223    # Could this make up a Class::AutoFill::__read_arglist which transparently
224    # makes object attributes from constructor arguments in a configurable way?
225  sub __parse_args {  sub __parse_args {
226    my $self = shift;    my $self = shift;
227    my %args;    my %args;
228    
229    if(@_ % 2 ) {    if ( @_ % 2 ) {
230      $args{dummy} = shift;      $args{dummy} = shift;
231      %args = (%args, @_);      %args = (%args, @_);
232    } else {    } else {
# Line 116  sub __parse_args { Line 237  sub __parse_args {
237  }  }
238    
239    
240  sub __init_default_macros {  sub __init_default_stylesheets {
241    my $self = shift;    my $self = shift;
242    $self->{MACROS}->{xupdate2xsl} = qq(<?xml version="1.0" encoding="ISO-8859-1"?>    if (my $payload = $self->__slurp_file("xupdate2xsl.xml")) {
243          $self->{XML}->{xsl}->{xupdate2xsl} = $payload;
244    <xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">    }
245    }
246    
247    sub __slurp_file {
248      my $self = shift;
249      my $filename = shift;
250        
251        <!--    # does file exist?
252        Purpose of this XML Stylesheet is to implement a set of templates    if (! -e $filename) {
253        to translate XUpdate lingo into an intermediate xslt stylesheet      $filename = dirname(__FILE__) . "/$filename";
254        which actually performs the update to the original xml document.      if (! -e $filename) {
255        -->        die("File $filename does not exist.");
256              }
257        <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>  
258        
259    );    open(FH, "<" . $filename);
260      my @lines = <FH>;
261      my $content = join("", @lines);
262      close(FH);
263      return $content;
264  }  }
265    
266  1;  1;
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