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13 <title>Python and bindings</title>
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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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28 <tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Main Menu</b></center></td></tr>
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40 <li><a href="API.html">The programming API</a></li>
41 <li><a href="python.html">Python and bindings</a></li>
42 <li><a href="internals.html">Library internals</a></li>
43 <li><a href="extensions.html">Writing extensions</a></li>
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46 <a href="xslt.html">flat page</a>, <a href="site.xsl">stylesheet</a>
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66 <tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr>
67 <tr><td bgcolor="#fffacd"><ul>
68 <li><a href="tutorial/libxslttutorial.html">Tutorial</a></li>
69 <li><a href="xsltproc.html">Man page for xsltproc</a></li>
70 <li><a href="http://mail.gnome.org/archives/xslt/">Mail archive</a></li>
71 <li><a href="http://xmlsoft.org/">XML libxml</a></li>
72 <li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li>
73 <li><a href="ftp://xmlsoft.org/">FTP</a></li>
74 <li><a href="http://www.fh-frankfurt.de/~igor/projects/libxml/">Windows binaries</a></li>
75 <li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
76 <li><a href="http://www.zveno.com/open_source/libxml2xslt.html">MacOsX binaries</a></li>
77 <li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li>
78 <li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxslt">Bug Tracker</a></li>
79 <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 <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
111 be maintained as part of the library in the future, though the Python
112 interface have not yet reached the maturity of the C API.</p>
113 <p>To install the Python bindings there are 2 options:</p>
115 <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
116 RPM</a> and the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
118 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
119 module distribution</a> corresponding to your installed version of
120 libxml2 and libxslt. Note that to install it you will need both libxml2
121 and libxslt installed and run "python setup.py build install" in the
124 <p>The distribution includes a set of examples and regression tests for the
125 python bindings in the <code>python/tests</code> directory. Here are some
126 excepts from those tests:</p>
128 <p>This is a basic test of XSLT interfaces: loading a stylesheet and a
129 document, transforming the document and saving the result.</p>
133 styledoc = libxml2.parseFile("test.xsl")
134 style = libxslt.parseStylesheetDoc(styledoc)
135 doc = libxml2.parseFile("test.xml")
136 result = style.applyStylesheet(doc, None)
137 style.saveResultToFilename("foo", result, 0)
138 style.freeStylesheet()
140 result.freeDoc()</pre>
141 <p>The Python module is called libxslt, you will also need the libxml2 module
142 for the operations on XML trees. Let's have a look at the objects manipulated
143 in that example and how is the processing done:</p>
146 <code>styledoc</code> : is a libxml2 document tree. It is obtained by
147 parsing the XML file "test.xsl" containing the stylesheet.</li>
149 <code>style</code> : this is a precompiled stylesheet ready to be used
150 by the following transformations (note the plural form, multiple
151 transformations can resuse the same stylesheet).</li>
153 <code>doc</code> : this is the document to apply the transformation to.
154 In this case it is simply generated by parsing it from a file but any
155 other processing is possible as long as one get a libxml2 Doc. Note that
156 HTML tree are suitable for XSLT processing in libxslt. This is actually
157 how this page is generated !</li>
159 <code>result</code> : this is a document generated by applying the
160 stylesheet to the document. Note that some of the stylesheet informations
161 may be related to the serialization of that document and as in this
162 example a specific saveResultToFilename() method of the stylesheet should
163 be used to save it to a file (in that case to "foo").</li>
165 <p>Also note the need to explicitely deallocate documents with freeDoc()
166 except for the stylesheet document which is freed when its compiled form is
167 garbage collected.</p>
169 <p>This one is a far more complex test. It shows how to modify the behaviour
170 of an XSLT transformation by passing parameters and how to extend the XSLT
171 engine with functions defined in python:</p>
181 # Small check to verify the context is correcly accessed
184 pctxt = libxslt.xpathParserContext(_obj=ctx)
185 ctxt = pctxt.context()
186 tctxt = ctxt.transformContext()
187 nodeName = tctxt.insertNode().name
191 return string.upper(str)
193 libxslt.registerExtModuleFunction("foo", "http://example.com/foo", f)</pre>
194 <p>This code defines and register an extension function. Note that the
195 function can be bound to any name (foo) and how the binding is also
196 associated to a namespace name "http://example.com/foo". From an XSLT point
197 of view the function just returns an upper case version of the string passed
198 as a parameter. But the first part of the function also read some contextual
199 information from the current XSLT processing environement, in that case it
200 looks for the current insertion node in the resulting output (either the
201 resulting document or the Result Value Tree being generated), and saves it to
202 a global variable for checking that the access actually worked.</p>
203 <p>For more informations on the xpathParserContext and transformContext
204 objects check the <a href="internals.html">libray internals description</a>.
205 The pctxt is actually an object from a class derived from the
206 libxml2.xpathParserContext() with just a couple more properties including the
207 possibility to look up the XSLT transformation context from the XPath
209 <pre>styledoc = libxml2.parseDoc("""
210 <xsl:stylesheet version='1.0'
211 xmlns:xsl='http://www.w3.org/1999/XSL/Transform'
212 xmlns:foo='http://example.com/foo'
213 xsl:exclude-result-prefixes='foo'>
215 <xsl:param name='bar'>failure</xsl:param>
216 <xsl:template match='/'>
217 <article><xsl:value-of select='foo:foo($bar)'/></article>
218 </xsl:template>
219 </xsl:stylesheet>
220 """)</pre>
221 <p>Here is a simple example of how to read an XML document from a python
222 string with libxml2. Note how this stylesheet:</p>
224 <li>Uses a global parameter <code>bar</code>
226 <li>Reference the extension function f</li>
227 <li>how the Namespace name "http://example.com/foo" has to be bound to a
229 <li>how that prefix is excluded from the output</li>
230 <li>how the function is called from the select</li>
232 <pre>style = libxslt.parseStylesheetDoc(styledoc)
233 doc = libxml2.parseDoc("<doc/>")
234 result = style.applyStylesheet(doc, { "bar": "'success'" })
235 style.freeStylesheet()
237 <p>that part is identical, to the basic example except that the
238 transformation is passed a dictionnary of parameters. Note that the string
239 passed "success" had to be quoted, otherwise it is interpreted as an XPath
240 query for the childs of root named "success".</p>
241 <pre>root = result.children
242 if root.name != "article":
243 print "Unexpected root node name"
245 if root.content != "SUCCESS":
246 print "Unexpected root node content, extension function failed"
248 if nodeName != 'article':
249 print "The function callback failed to access its context"
252 result.freeDoc()</pre>
253 <p>That part just verifies that the transformation worked, that the parameter
254 got properly passed to the engine, that the function f() got called and that
255 it properly accessed the context to find the name of the insertion node.</p>
256 <h3>pyxsltproc.py:</h3>
257 <p>this module is a bit too long to be described there but it is basically a
258 rewrite of the xsltproc command line interface of libxslt in Python. It
259 provides nearly all the functionalities of xsltproc and can be used as a base
260 module to write Python customized XSLT processors. One of the thing to notice
262 <pre>libxml2.lineNumbersDefault(1)
263 libxml2.substituteEntitiesDefault(1)</pre>
264 <p>those two calls in the main() function are needed to force the libxml2
265 processor to generate DOM trees compliant with the XPath data model.</p>
266 <p><a href="bugs.html">Daniel Veillard</a></p>
267 </td></tr></table></td></tr></table></td></tr></table></td>
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