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1<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd">
2<html>
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13<title>Python and bindings</title>
14</head>
15<body bgcolor="#8b7765" text="#000000" link="#000000" vlink="#000000">
16<table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr>
17<td width="100">
18<a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo"></a><a href="http://www.redhat.com"><img src="redhat.gif" alt="Red Hat Logo"></a><div align="left"><a href="http://xmlsoft.org/XSLT/"><img src="Libxslt-Logo-180x168.gif" alt="Made with Libxslt Logo"></a></div>
19</td>
20<td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center">
21<h1>The XSLT C library for Gnome</h1>
22<h2>Python and bindings</h2>
23</td></tr></table></td></tr></table></td>
24</tr></table>
25<table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr>
26<td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td>
27<table width="100%" border="0" cellspacing="1" cellpadding="3">
28<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Main Menu</b></center></td></tr>
29<tr><td bgcolor="#fffacd">
30<form action="search.php" enctype="application/x-www-form-urlencoded" method="GET">
31<input name="query" type="TEXT" size="20" value=""><input name="submit" type="submit" value="Search ...">
32</form>
33<ul>
34<li><a href="index.html">Home</a></li>
35<li><a href="intro.html">Introduction</a></li>
36<li><a href="docs.html">Documentation</a></li>
37<li><a href="bugs.html">Reporting bugs and getting help</a></li>
38<li><a href="help.html">How to help</a></li>
39<li><a href="downloads.html">Downloads</a></li>
40<li><a href="FAQ.html">FAQ</a></li>
41<li><a href="news.html">News</a></li>
42<li><a href="xsltproc2.html">The xsltproc tool</a></li>
43<li><a href="docbook.html">DocBook</a></li>
44<li><a href="API.html">The programming API</a></li>
45<li><a href="python.html">Python and bindings</a></li>
46<li><a href="internals.html">Library internals</a></li>
47<li><a href="extensions.html">Writing extensions</a></li>
48<li><a href="contribs.html">Contributions</a></li>
49<li>
50<a href="xslt.html">flat page</a>, <a href="site.xsl">stylesheet</a>
51</li>
52</ul>
53</td></tr>
54</table>
55<table width="100%" border="0" cellspacing="1" cellpadding="3">
56<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr>
57<tr><td bgcolor="#fffacd"><ul>
58<li><a href="tutorial/libxslttutorial.html">Tutorial</a></li>
59<li><a href="xsltproc.html">Man page for xsltproc</a></li>
60<li><a href="http://mail.gnome.org/archives/xslt/">Mail archive</a></li>
61<li><a href="http://xmlsoft.org/">XML libxml</a></li>
62<li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li>
63<li><a href="ftp://xmlsoft.org/">FTP</a></li>
64<li><a href="http://www.zlatkovic.com/projects/libxml/">Windows binaries</a></li>
65<li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
66<li><a href="http://www.zveno.com/open_source/libxml2xslt.html">MacOsX binaries</a></li>
67<li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li>
68<li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxslt">Bug Tracker</a></li>
69<li><a href="http://xsldbg.sourceforge.net/">Xsldbg Debugger</a></li>
70</ul></td></tr>
71</table>
72<table width="100%" border="0" cellspacing="1" cellpadding="3">
73<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr>
74<tr><td bgcolor="#fffacd"><ul>
75<li><a href="APIchunk0.html">Alphabetic</a></li>
76<li><a href="APIconstructors.html">Constructors</a></li>
77<li><a href="APIfunctions.html">Functions/Types</a></li>
78<li><a href="APIfiles.html">Modules</a></li>
79<li><a href="APIsymbols.html">Symbols</a></li>
80</ul></td></tr>
81</table>
82</td></tr></table></td>
83<td valign="top" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%"><tr><td><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table border="0" cellpadding="3" cellspacing="1" width="100%"><tr><td bgcolor="#fffacd">
84<p>There is a number of language bindings and wrappers available for libxml2,
85the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
86(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
87order to get updates to this list or to discuss the specific topic of libxml2
88or libxslt wrappers or bindings:</p>
89<ul>
90<li>
91<a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
92    Sergeant</a> developped <a href="http://axkit.org/download/">XML::LibXML
93    and XML::LibXSLT</a>, a perl wrapper for libxml2/libxslt as part of the
94    <a href="http://axkit.com/">AxKit XML application server</a>
95</li>
96  <li>
97<a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
98    earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>
99</li>
100  <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
101    libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
102  <li>Wai-Sun &quot;Squidster&quot; Chia provides <a href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a>  and
103    libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
104    maintained by Tobias Peters.</li>
105  <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
106    Tcl</a>
107</li>
108</ul>
109<p>The libxslt Python module depends on the <a href="http://xmlsoft.org/python.html">libxml2 Python</a> module.</p>
110<p>The distribution includes a set of Python bindings, which are garanteed to
111be maintained as part of the library in the future, though the Python
112interface have not yet reached the maturity of the C API.</p>
113<p>
114<a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
115maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
116of the Python bindings</a>.</p>
117<p>Note to people interested in building bindings, the API is formalized as
118<a href="libxslt-api.xml">an XML API description file</a> which allows to
119automate a large part of the Python bindings, this includes function
120descriptions, enums, structures, typedefs, etc... The Python script used to
121build the bindings is python/generator.py in the source distribution.</p>
122<p>To install the Python bindings there are 2 options:</p>
123<ul>
124<li>If you use an RPM based distribution, simply install the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxml2-python">libxml2-python
125    RPM</a> and the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
126    RPM</a>.</li>
127  <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
128    module distribution</a> corresponding to your installed version of
129    libxml2 and libxslt. Note that to install it you will need both libxml2
130    and libxslt installed and run &quot;python setup.py build install&quot; in the
131    module tree.</li>
132</ul>
133<p>The distribution includes a set of examples and regression tests for the
134python bindings in the <code>python/tests</code> directory. Here are some
135excepts from those tests:</p>
136<h3>basic.py:</h3>
137<p>This is a basic test of XSLT interfaces: loading a stylesheet and a
138document, transforming the document and saving the result.</p>
139<pre>import libxml2
140import libxslt
141
142styledoc = libxml2.parseFile(&quot;test.xsl&quot;)
143style = libxslt.parseStylesheetDoc(styledoc)
144doc = libxml2.parseFile(&quot;test.xml&quot;)
145result = style.applyStylesheet(doc, None)
146style.saveResultToFilename(&quot;foo&quot;, result, 0)
147style.freeStylesheet()
148doc.freeDoc()
149result.freeDoc()</pre>
150<p>The Python module is called libxslt, you will also need the libxml2 module
151for the operations on XML trees. Let's have a look at the objects manipulated
152in that example and how is the processing done:</p>
153<ul>
154<li>
155<code>styledoc</code> : is a libxml2 document tree. It is obtained by
156    parsing the XML file &quot;test.xsl&quot; containing the stylesheet.</li>
157  <li>
158<code>style</code> : this is a precompiled stylesheet ready to be used
159    by the following transformations (note the plural form, multiple
160    transformations can resuse the same stylesheet).</li>
161  <li>
162<code>doc</code> : this is the document to apply the transformation to.
163    In this case it is simply generated by parsing it from a file but any
164    other processing is possible as long as one get a libxml2 Doc. Note that
165    HTML tree are suitable for XSLT processing in libxslt. This is actually
166    how this page is generated !</li>
167  <li>
168<code>result</code> : this is a document generated by applying the
169    stylesheet to the document. Note that some of the stylesheet informations
170    may be related to the serialization of that document and as in this
171    example a specific saveResultToFilename() method of the stylesheet should
172    be used to save it to a file (in that case to &quot;foo&quot;).</li>
173</ul>
174<p>Also note the need to explicitely deallocate documents with freeDoc()
175except for the stylesheet document which is freed when its compiled form is
176garbage collected.</p>
177<h3>extfunc.py:</h3>
178<p>This one is a far more complex test. It shows how to modify the behaviour
179of an XSLT transformation by passing parameters and how to extend the XSLT
180engine with functions defined in python:</p>
181<pre>import libxml2
182import libxslt
183import string
184
185nodeName = None
186def f(ctx, str):
187    global nodeName
188
189    #
190    # Small check to verify the context is correcly accessed
191    #
192    try:
193        pctxt = libxslt.xpathParserContext(_obj=ctx)
194        ctxt = pctxt.context()
195        tctxt = ctxt.transformContext()
196        nodeName = tctxt.insertNode().name
197    except:
198        pass
199
200    return string.upper(str)
201
202libxslt.registerExtModuleFunction(&quot;foo&quot;, &quot;http://example.com/foo&quot;, f)</pre>
203<p>This code defines and register an extension function. Note that the
204function can be bound to any name (foo) and how the binding is also
205associated to a namespace name &quot;http://example.com/foo&quot;. From an XSLT point
206of view the function just returns an upper case version of the string passed
207as a parameter. But the first part of the function also read some contextual
208information from the current XSLT processing environement, in that case it
209looks for the current insertion node in the resulting output (either the
210resulting document or the Result Value Tree being generated), and saves it to
211a global variable for checking that the access actually worked.</p>
212<p>For more informations on the xpathParserContext and transformContext
213objects check the <a href="internals.html">libray internals description</a>.
214The pctxt is actually an object from a class derived from the
215libxml2.xpathParserContext() with just a couple more properties including the
216possibility to look up the XSLT transformation context from the XPath
217context.</p>
218<pre>styledoc = libxml2.parseDoc(&quot;&quot;&quot;
219&lt;xsl:stylesheet version='1.0'
220  xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
221  xmlns:foo='http://example.com/foo'
222  xsl:exclude-result-prefixes='foo'&gt;
223
224  &lt;xsl:param name='bar'&gt;failure&lt;/xsl:param&gt;
225  &lt;xsl:template match='/'&gt;
226    &lt;article&gt;&lt;xsl:value-of select='foo:foo($bar)'/&gt;&lt;/article&gt;
227  &lt;/xsl:template&gt;
228&lt;/xsl:stylesheet&gt;
229&quot;&quot;&quot;)</pre>
230<p>Here is a simple example of how to read an XML document from a python
231string with libxml2. Note how this stylesheet:</p>
232<ul>
233<li>Uses a global parameter <code>bar</code>
234</li>
235  <li>Reference the extension function f</li>
236  <li>how the Namespace name &quot;http://example.com/foo&quot; has to be bound to a
237    prefix</li>
238  <li>how that prefix is excluded from the output</li>
239  <li>how the function is called from the select</li>
240</ul>
241<pre>style = libxslt.parseStylesheetDoc(styledoc)
242doc = libxml2.parseDoc(&quot;&lt;doc/&gt;&quot;)
243result = style.applyStylesheet(doc, { &quot;bar&quot;: &quot;'success'&quot; })
244style.freeStylesheet()
245doc.freeDoc()</pre>
246<p>that part is identical, to the basic example except that the
247transformation is passed a dictionnary of parameters. Note that the string
248passed &quot;success&quot; had to be quoted, otherwise it is interpreted as an XPath
249query for the childs of root named &quot;success&quot;.</p>
250<pre>root = result.children
251if root.name != &quot;article&quot;:
252    print &quot;Unexpected root node name&quot;
253    sys.exit(1)
254if root.content != &quot;SUCCESS&quot;:
255    print &quot;Unexpected root node content, extension function failed&quot;
256    sys.exit(1)
257if nodeName != 'article':
258    print &quot;The function callback failed to access its context&quot;
259    sys.exit(1)
260
261result.freeDoc()</pre>
262<p>That part just verifies that the transformation worked, that the parameter
263got properly passed to the engine, that the function f() got called and that
264it properly accessed the context to find the name of the insertion node.</p>
265<h3>pyxsltproc.py:</h3>
266<p>this module is a bit too long to be described there but it is basically a
267rewrite of the xsltproc command line interface of libxslt in Python. It
268provides nearly all the functionalities of xsltproc and can be used as a base
269module to write Python customized XSLT processors. One of the thing to notice
270are:</p>
271<pre>libxml2.lineNumbersDefault(1)
272libxml2.substituteEntitiesDefault(1)</pre>
273<p>those two calls in the main() function are needed to force the libxml2
274processor to generate DOM trees compliant with the XPath data model.</p>
275<p><a href="bugs.html">Daniel Veillard</a></p>
276</td></tr></table></td></tr></table></td></tr></table></td>
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