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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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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>
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84 <p>There is a number of language bindings and wrappers available for libxml2,
85 the 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
87 order to get updates to this list or to discuss the specific topic of libxml2
88 or libxslt wrappers or bindings:</p>
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>
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>
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 "Squidster" 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
109 <a href="mailto:xmlwrapp@pmade.org">Peter Jones</a> maintains C++
110 bindings for libxslt within <a href="http://pmade.org/pjones/software/xmlwrapp/">xmlwrapp</a>
113 <p>The libxslt Python module depends on the <a href="http://xmlsoft.org/python.html">libxml2 Python</a> module.</p>
114 <p>The distribution includes a set of Python bindings, which are garanteed to
115 be maintained as part of the library in the future, though the Python
116 interface have not yet reached the maturity of the C API.</p>
118 <a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
119 maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
120 of the Python bindings</a>.</p>
121 <p>Note to people interested in building bindings, the API is formalized as
122 <a href="libxslt-api.xml">an XML API description file</a> which allows to
123 automate a large part of the Python bindings, this includes function
124 descriptions, enums, structures, typedefs, etc... The Python script used to
125 build the bindings is python/generator.py in the source distribution.</p>
126 <p>To install the Python bindings there are 2 options:</p>
128 <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
129 RPM</a> and the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
131 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
132 module distribution</a> corresponding to your installed version of
133 libxml2 and libxslt. Note that to install it you will need both libxml2
134 and libxslt installed and run "python setup.py build install" in the
137 <p>The distribution includes a set of examples and regression tests for the
138 python bindings in the <code>python/tests</code> directory. Here are some
139 excepts from those tests:</p>
141 <p>This is a basic test of XSLT interfaces: loading a stylesheet and a
142 document, transforming the document and saving the result.</p>
146 styledoc = libxml2.parseFile("test.xsl")
147 style = libxslt.parseStylesheetDoc(styledoc)
148 doc = libxml2.parseFile("test.xml")
149 result = style.applyStylesheet(doc, None)
150 style.saveResultToFilename("foo", result, 0)
151 style.freeStylesheet()
153 result.freeDoc()</pre>
154 <p>The Python module is called libxslt, you will also need the libxml2 module
155 for the operations on XML trees. Let's have a look at the objects manipulated
156 in that example and how is the processing done:</p>
159 <code>styledoc</code> : is a libxml2 document tree. It is obtained by
160 parsing the XML file "test.xsl" containing the stylesheet.</li>
162 <code>style</code> : this is a precompiled stylesheet ready to be used
163 by the following transformations (note the plural form, multiple
164 transformations can resuse the same stylesheet).</li>
166 <code>doc</code> : this is the document to apply the transformation to.
167 In this case it is simply generated by parsing it from a file but any
168 other processing is possible as long as one get a libxml2 Doc. Note that
169 HTML tree are suitable for XSLT processing in libxslt. This is actually
170 how this page is generated !</li>
172 <code>result</code> : this is a document generated by applying the
173 stylesheet to the document. Note that some of the stylesheet informations
174 may be related to the serialization of that document and as in this
175 example a specific saveResultToFilename() method of the stylesheet should
176 be used to save it to a file (in that case to "foo").</li>
178 <p>Also note the need to explicitely deallocate documents with freeDoc()
179 except for the stylesheet document which is freed when its compiled form is
180 garbage collected.</p>
182 <p>This one is a far more complex test. It shows how to modify the behaviour
183 of an XSLT transformation by passing parameters and how to extend the XSLT
184 engine with functions defined in python:</p>
194 # Small check to verify the context is correcly accessed
197 pctxt = libxslt.xpathParserContext(_obj=ctx)
198 ctxt = pctxt.context()
199 tctxt = ctxt.transformContext()
200 nodeName = tctxt.insertNode().name
204 return string.upper(str)
206 libxslt.registerExtModuleFunction("foo", "http://example.com/foo", f)</pre>
207 <p>This code defines and register an extension function. Note that the
208 function can be bound to any name (foo) and how the binding is also
209 associated to a namespace name "http://example.com/foo". From an XSLT point
210 of view the function just returns an upper case version of the string passed
211 as a parameter. But the first part of the function also read some contextual
212 information from the current XSLT processing environement, in that case it
213 looks for the current insertion node in the resulting output (either the
214 resulting document or the Result Value Tree being generated), and saves it to
215 a global variable for checking that the access actually worked.</p>
216 <p>For more informations on the xpathParserContext and transformContext
217 objects check the <a href="internals.html">libray internals description</a>.
218 The pctxt is actually an object from a class derived from the
219 libxml2.xpathParserContext() with just a couple more properties including the
220 possibility to look up the XSLT transformation context from the XPath
222 <pre>styledoc = libxml2.parseDoc("""
223 <xsl:stylesheet version='1.0'
224 xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
225 xmlns:foo='http://example.com/foo'
226 xsl:exclude-result-prefixes='foo'>
228 <xsl:param name='bar'>failure</xsl:param>
229 <xsl:template match='/'>
230 <article><xsl:value-of select='foo:foo($bar)'/></article>
231 </xsl:template>
232 </xsl:stylesheet>
233 """)</pre>
234 <p>Here is a simple example of how to read an XML document from a python
235 string with libxml2. Note how this stylesheet:</p>
237 <li>Uses a global parameter <code>bar</code>
239 <li>Reference the extension function f</li>
240 <li>how the Namespace name "http://example.com/foo" has to be bound to a
242 <li>how that prefix is excluded from the output</li>
243 <li>how the function is called from the select</li>
245 <pre>style = libxslt.parseStylesheetDoc(styledoc)
246 doc = libxml2.parseDoc("<doc/>")
247 result = style.applyStylesheet(doc, { "bar": "'success'" })
248 style.freeStylesheet()
250 <p>that part is identical, to the basic example except that the
251 transformation is passed a dictionnary of parameters. Note that the string
252 passed "success" had to be quoted, otherwise it is interpreted as an XPath
253 query for the childs of root named "success".</p>
254 <pre>root = result.children
255 if root.name != "article":
256 print "Unexpected root node name"
258 if root.content != "SUCCESS":
259 print "Unexpected root node content, extension function failed"
261 if nodeName != 'article':
262 print "The function callback failed to access its context"
265 result.freeDoc()</pre>
266 <p>That part just verifies that the transformation worked, that the parameter
267 got properly passed to the engine, that the function f() got called and that
268 it properly accessed the context to find the name of the insertion node.</p>
269 <h3>pyxsltproc.py:</h3>
270 <p>this module is a bit too long to be described there but it is basically a
271 rewrite of the xsltproc command line interface of libxslt in Python. It
272 provides nearly all the functionalities of xsltproc and can be used as a base
273 module to write Python customized XSLT processors. One of the thing to notice
275 <pre>libxml2.lineNumbersDefault(1)
276 libxml2.substituteEntitiesDefault(1)</pre>
277 <p>those two calls in the main() function are needed to force the libxml2
278 processor to generate DOM trees compliant with the XPath data model.</p>
279 <p><a href="bugs.html">Daniel Veillard</a></p>
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