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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>
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21 <h1>The XSLT C library for Gnome</h1>
22 <h2>Python and bindings</h2>
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47 <li><a href="extensions.html">Writing extensions</a></li>
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50 <a href="xslt.html">flat page</a>, <a href="site.xsl">stylesheet</a>
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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 <li><a href="http://www.mod-xslt.com/mod-xslt/">Apache module</a></li>
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85 <p>There is a number of language bindings and wrappers available for libxml2,
86 the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
87 (<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
88 order to get updates to this list or to discuss the specific topic of libxml2
89 or libxslt wrappers or bindings:</p>
92 <a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
93 Sergeant</a> developped <a href="http://axkit.org/download/">XML::LibXML
94 and XML::LibXSLT</a>, a perl wrapper for libxml2/libxslt as part of the
95 <a href="http://axkit.com/">AxKit XML application server</a>
98 <a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
99 earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>
101 <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
102 libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
103 <li>Wai-Sun "Squidster" Chia provides <a href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
104 libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
105 maintained by Tobias Peters.</li>
106 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
110 <a href="mailto:xmlwrapp@pmade.org">Peter Jones</a> maintains C++
111 bindings for libxslt within <a href="http://pmade.org/pjones/software/xmlwrapp/">xmlwrapp</a>
114 <p>The libxslt Python module depends on the <a href="http://xmlsoft.org/python.html">libxml2 Python</a> module.</p>
115 <p>The distribution includes a set of Python bindings, which are garanteed to
116 be maintained as part of the library in the future, though the Python
117 interface have not yet reached the maturity of the C API.</p>
119 <a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
120 maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
121 of the Python bindings</a>.</p>
122 <p>Note to people interested in building bindings, the API is formalized as
123 <a href="libxslt-api.xml">an XML API description file</a> which allows to
124 automate a large part of the Python bindings, this includes function
125 descriptions, enums, structures, typedefs, etc... The Python script used to
126 build the bindings is python/generator.py in the source distribution.</p>
127 <p>To install the Python bindings there are 2 options:</p>
129 <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
130 RPM</a> and the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
132 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
133 module distribution</a> corresponding to your installed version of
134 libxml2 and libxslt. Note that to install it you will need both libxml2
135 and libxslt installed and run "python setup.py build install" in the
138 <p>The distribution includes a set of examples and regression tests for the
139 python bindings in the <code>python/tests</code> directory. Here are some
140 excepts from those tests:</p>
142 <p>This is a basic test of XSLT interfaces: loading a stylesheet and a
143 document, transforming the document and saving the result.</p>
147 styledoc = libxml2.parseFile("test.xsl")
148 style = libxslt.parseStylesheetDoc(styledoc)
149 doc = libxml2.parseFile("test.xml")
150 result = style.applyStylesheet(doc, None)
151 style.saveResultToFilename("foo", result, 0)
152 style.freeStylesheet()
154 result.freeDoc()</pre>
155 <p>The Python module is called libxslt, you will also need the libxml2 module
156 for the operations on XML trees. Let's have a look at the objects manipulated
157 in that example and how is the processing done:</p>
160 <code>styledoc</code> : is a libxml2 document tree. It is obtained by
161 parsing the XML file "test.xsl" containing the stylesheet.</li>
163 <code>style</code> : this is a precompiled stylesheet ready to be used
164 by the following transformations (note the plural form, multiple
165 transformations can resuse the same stylesheet).</li>
167 <code>doc</code> : this is the document to apply the transformation to.
168 In this case it is simply generated by parsing it from a file but any
169 other processing is possible as long as one get a libxml2 Doc. Note that
170 HTML tree are suitable for XSLT processing in libxslt. This is actually
171 how this page is generated !</li>
173 <code>result</code> : this is a document generated by applying the
174 stylesheet to the document. Note that some of the stylesheet informations
175 may be related to the serialization of that document and as in this
176 example a specific saveResultToFilename() method of the stylesheet should
177 be used to save it to a file (in that case to "foo").</li>
179 <p>Also note the need to explicitely deallocate documents with freeDoc()
180 except for the stylesheet document which is freed when its compiled form is
181 garbage collected.</p>
183 <p>This one is a far more complex test. It shows how to modify the behaviour
184 of an XSLT transformation by passing parameters and how to extend the XSLT
185 engine with functions defined in python:</p>
195 # Small check to verify the context is correcly accessed
198 pctxt = libxslt.xpathParserContext(_obj=ctx)
199 ctxt = pctxt.context()
200 tctxt = ctxt.transformContext()
201 nodeName = tctxt.insertNode().name
205 return string.upper(str)
207 libxslt.registerExtModuleFunction("foo", "http://example.com/foo", f)</pre>
208 <p>This code defines and register an extension function. Note that the
209 function can be bound to any name (foo) and how the binding is also
210 associated to a namespace name "http://example.com/foo". From an XSLT point
211 of view the function just returns an upper case version of the string passed
212 as a parameter. But the first part of the function also read some contextual
213 information from the current XSLT processing environement, in that case it
214 looks for the current insertion node in the resulting output (either the
215 resulting document or the Result Value Tree being generated), and saves it to
216 a global variable for checking that the access actually worked.</p>
217 <p>For more informations on the xpathParserContext and transformContext
218 objects check the <a href="internals.html">libray internals description</a>.
219 The pctxt is actually an object from a class derived from the
220 libxml2.xpathParserContext() with just a couple more properties including the
221 possibility to look up the XSLT transformation context from the XPath
223 <pre>styledoc = libxml2.parseDoc("""
224 <xsl:stylesheet version='1.0'
225 xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
226 xmlns:foo='http://example.com/foo'
227 xsl:exclude-result-prefixes='foo'>
229 <xsl:param name='bar'>failure</xsl:param>
230 <xsl:template match='/'>
231 <article><xsl:value-of select='foo:foo($bar)'/></article>
232 </xsl:template>
233 </xsl:stylesheet>
234 """)</pre>
235 <p>Here is a simple example of how to read an XML document from a python
236 string with libxml2. Note how this stylesheet:</p>
238 <li>Uses a global parameter <code>bar</code>
240 <li>Reference the extension function f</li>
241 <li>how the Namespace name "http://example.com/foo" has to be bound to a
243 <li>how that prefix is excluded from the output</li>
244 <li>how the function is called from the select</li>
246 <pre>style = libxslt.parseStylesheetDoc(styledoc)
247 doc = libxml2.parseDoc("<doc/>")
248 result = style.applyStylesheet(doc, { "bar": "'success'" })
249 style.freeStylesheet()
251 <p>that part is identical, to the basic example except that the
252 transformation is passed a dictionnary of parameters. Note that the string
253 passed "success" had to be quoted, otherwise it is interpreted as an XPath
254 query for the childs of root named "success".</p>
255 <pre>root = result.children
256 if root.name != "article":
257 print "Unexpected root node name"
259 if root.content != "SUCCESS":
260 print "Unexpected root node content, extension function failed"
262 if nodeName != 'article':
263 print "The function callback failed to access its context"
266 result.freeDoc()</pre>
267 <p>That part just verifies that the transformation worked, that the parameter
268 got properly passed to the engine, that the function f() got called and that
269 it properly accessed the context to find the name of the insertion node.</p>
270 <h3>pyxsltproc.py:</h3>
271 <p>this module is a bit too long to be described there but it is basically a
272 rewrite of the xsltproc command line interface of libxslt in Python. It
273 provides nearly all the functionalities of xsltproc and can be used as a base
274 module to write Python customized XSLT processors. One of the thing to notice
276 <pre>libxml2.lineNumbersDefault(1)
277 libxml2.substituteEntitiesDefault(1)</pre>
278 <p>those two calls in the main() function are needed to force the libxml2
279 processor to generate DOM trees compliant with the XPath data model.</p>
280 <p><a href="bugs.html">Daniel Veillard</a></p>
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