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gerrit-public.fairphone.software / fp2-dev / platform / external / libxml2 / 76575769f304c80d6d0800b33ec625dd25b6dd49 / . / doc / python.html
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14<title>Python and bindings</title>
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18<td width="180">
Daniel Veillard8f40f1e2002-08-28 21:18:45 +0000[diff] [blame]19<a href="http://www.gnome.org/"><img src="gnome2.png" alt="Gnome2 Logo"></a><a href="http://www.w3.org/Status"><img src="w3c.png" alt="W3C 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/"><img src="Libxml2-Logo-180x168.gif" alt="Made with Libxml2 Logo"></a></div>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]20</td>
21<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">
22<h1>The XML C library for Gnome</h1>
23<h2>Python and bindings</h2>
24</td></tr></table></td></tr></table></td>
25</tr></table>
26<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>
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28<table width="100%" border="0" cellspacing="1" cellpadding="3">
29<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Main Menu</b></center></td></tr>
30<tr><td bgcolor="#fffacd"><ul>
31<li><a href="index.html">Home</a></li>
32<li><a href="intro.html">Introduction</a></li>
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34<li><a href="docs.html">Documentation</a></li>
35<li><a href="bugs.html">Reporting bugs and getting help</a></li>
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40<li><a href="XSLT.html">XSLT</a></li>
41<li><a href="python.html">Python and bindings</a></li>
42<li><a href="architecture.html">libxml architecture</a></li>
43<li><a href="tree.html">The tree output</a></li>
44<li><a href="interface.html">The SAX interface</a></li>
45<li><a href="xmldtd.html">Validation &amp; DTDs</a></li>
46<li><a href="xmlmem.html">Memory Management</a></li>
47<li><a href="encoding.html">Encodings support</a></li>
48<li><a href="xmlio.html">I/O Interfaces</a></li>
49<li><a href="catalog.html">Catalog support</a></li>
50<li><a href="library.html">The parser interfaces</a></li>
51<li><a href="entities.html">Entities or no entities</a></li>
52<li><a href="namespaces.html">Namespaces</a></li>
53<li><a href="upgrade.html">Upgrading 1.x code</a></li>
54<li><a href="threads.html">Thread safety</a></li>
55<li><a href="DOM.html">DOM Principles</a></li>
56<li><a href="example.html">A real example</a></li>
57<li><a href="contribs.html">Contributions</a></li>
Daniel Veillardfc59c092002-06-05 14:48:26 +0000[diff] [blame]58<li><a href="tutorial/index.html">Tutorial</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]59<li>
60<a href="xml.html">flat page</a>, <a href="site.xsl">stylesheet</a>
61</li>
62</ul></td></tr>
63</table>
64<table width="100%" border="0" cellspacing="1" cellpadding="3">
65<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr>
66<tr><td bgcolor="#fffacd"><ul>
67<li><a href="APIchunk0.html">Alphabetic</a></li>
68<li><a href="APIconstructors.html">Constructors</a></li>
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72</ul></td></tr>
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74<table width="100%" border="0" cellspacing="1" cellpadding="3">
75<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr>
76<tr><td bgcolor="#fffacd"><ul>
77<li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li>
78<li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li>
79<li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]80<li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]81<li><a href="ftp://xmlsoft.org/">FTP</a></li>
82<li><a href="http://www.fh-frankfurt.de/~igor/projects/libxml/">Windows binaries</a></li>
83<li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
Daniel Veillarde6d8e202002-05-02 06:11:10 +0000[diff] [blame]84<li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]85<li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml&amp;product=libxml2">Bug Tracker</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]86</ul></td></tr>
87</table>
88</td></tr></table></td>
89<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">
Daniel Veillard42766c02002-08-22 20:52:17 +0000[diff] [blame]90<p>There are a number of language bindings and wrappers available for
91libxml2, the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]92(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
93order to get updates to this list or to discuss the specific topic of libxml2
94or libxslt wrappers or bindings:</p>
95<ul>
96<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]97<a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
98 for libxml:<br>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]99 Website: <a href="http://lusis.org/~ari/xml%2B%2B/">http://lusis.org/~ari/xml++/</a><br>
100 Download: <a href="http://lusis.org/~ari/xml%2B%2B/libxml%2B%2B.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]101</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]102 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
103 based on the gdome2 bindings</a> maintained by Tobias Peters.</li>
104 <li>and a third C++ wrapper by Peter Jones &lt;pjones@pmade.org&gt;
Daniel Veillard9b6fd302002-05-13 12:06:47 +0000[diff] [blame]105 <p>Website: <a href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a>
106</p>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]107 </li>
108 <li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]109<a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]110 Sergeant</a> developed <a href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]111 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]112 application server</a>.</li>
113 <li>
Daniel Veillard21473672002-06-17 07:29:22 +0000[diff] [blame]114<a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]115 earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li>
116 <li>Gopal.V and Peter Minten develop <a href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of
117 C# libxml2 bindings.</li>
118 <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
119 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li>
120 <li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2
121 implementation for Kylix2/D5/D6 from Borland.</li>
122 <li>Wai-Sun &quot;Squidster&quot; Chia provides <a href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]123 libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
124 maintained by Tobias Peters.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]125 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
126 Tcl</a>.</li>
127 <li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]128</ul>
Daniel Veillardc0801af2002-05-28 16:28:42 +0000[diff] [blame]129<p>The distribution includes a set of Python bindings, which are guaranteed
130to be maintained as part of the library in the future, though the Python
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]131interface have not yet reached the maturity of the C API.</p>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]132<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]133<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]134<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
135 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
136 RPM</a>).</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]137 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]138 module distribution</a> corresponding to your installed version of
139 libxml2 and libxslt. Note that to install it you will need both libxml2
140 and libxslt installed and run &quot;python setup.py build install&quot; in the
141 module tree.</li>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]142</ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]143<p>The distribution includes a set of examples and regression tests for the
144python bindings in the <code>python/tests</code> directory. Here are some
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]145excerpts from those tests:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]146<h3>tst.py:</h3>
147<p>This is a basic test of the file interface and DOM navigation:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]148<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]149
150doc = libxml2.parseFile(&quot;tst.xml&quot;)
151if doc.name != &quot;tst.xml&quot;:
152 print &quot;doc.name failed&quot;
153 sys.exit(1)
154root = doc.children
155if root.name != &quot;doc&quot;:
156 print &quot;root.name failed&quot;
157 sys.exit(1)
158child = root.children
159if child.name != &quot;foo&quot;:
160 print &quot;child.name failed&quot;
161 sys.exit(1)
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]162doc.freeDoc()</pre>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]163<p>The Python module is called libxml2; parseFile is the equivalent of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]164xmlParseFile (most of the bindings are automatically generated, and the xml
165prefix is removed and the casing convention are kept). All node seen at the
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]166binding level share the same subset of accessors:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]167<ul>
168<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]169<code>name</code> : returns the node name</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]170 <li>
Daniel Veillardc0801af2002-05-28 16:28:42 +0000[diff] [blame]171<code>type</code> : returns a string indicating the node type</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]172 <li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]173<code>content</code> : returns the content of the node, it is based on
174 xmlNodeGetContent() and hence is recursive.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]175 <li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]176<code>parent</code> , <code>children</code>, <code>last</code>,
177 <code>next</code>, <code>prev</code>, <code>doc</code>,
178 <code>properties</code>: pointing to the associated element in the tree,
179 those may return None in case no such link exists.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]180</ul>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]181<p>Also note the need to explicitly deallocate documents with freeDoc() .
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]182Reference counting for libxml2 trees would need quite a lot of work to
183function properly, and rather than risk memory leaks if not implemented
184correctly it sounds safer to have an explicit function to free a tree. The
185wrapper python objects like doc, root or child are them automatically garbage
186collected.</p>
187<h3>validate.py:</h3>
188<p>This test check the validation interfaces and redirection of error
189messages:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]190<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]191
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]192#deactivate error messages from the validation
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]193def noerr(ctx, str):
194 pass
195
196libxml2.registerErrorHandler(noerr, None)
197
198ctxt = libxml2.createFileParserCtxt(&quot;invalid.xml&quot;)
199ctxt.validate(1)
200ctxt.parseDocument()
201doc = ctxt.doc()
202valid = ctxt.isValid()
203doc.freeDoc()
204if valid != 0:
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]205 print &quot;validity check failed&quot;</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]206<p>The first thing to notice is the call to registerErrorHandler(), it
207defines a new error handler global to the library. It is used to avoid seeing
208the error messages when trying to validate the invalid document.</p>
209<p>The main interest of that test is the creation of a parser context with
210createFileParserCtxt() and how the behaviour can be changed before calling
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]211parseDocument() . Similarly the informations resulting from the parsing phase
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]212are also available using context methods.</p>
213<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
214C function interfaces in terms of objects method as much as possible. The
215best to get a complete view of what methods are supported is to look at the
216libxml2.py module containing all the wrappers.</p>
217<h3>push.py:</h3>
218<p>This test show how to activate the push parser interface:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]219<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]220
221ctxt = libxml2.createPushParser(None, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
222ctxt.parseChunk(&quot;/&gt;&quot;, 2, 1)
223doc = ctxt.doc()
224
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]225doc.freeDoc()</pre>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]226<p>The context is created with a special call based on the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]227xmlCreatePushParser() from the C library. The first argument is an optional
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]228SAX callback object, then the initial set of data, the length and the name of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]229the resource in case URI-References need to be computed by the parser.</p>
230<p>Then the data are pushed using the parseChunk() method, the last call
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]231setting the third argument terminate to 1.</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]232<h3>pushSAX.py:</h3>
233<p>this test show the use of the event based parsing interfaces. In this case
234the parser does not build a document, but provides callback information as
235the parser makes progresses analyzing the data being provided:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]236<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]237log = &quot;&quot;
238
239class callback:
240 def startDocument(self):
241 global log
242 log = log + &quot;startDocument:&quot;
243
244 def endDocument(self):
245 global log
246 log = log + &quot;endDocument:&quot;
247
248 def startElement(self, tag, attrs):
249 global log
250 log = log + &quot;startElement %s %s:&quot; % (tag, attrs)
251
252 def endElement(self, tag):
253 global log
254 log = log + &quot;endElement %s:&quot; % (tag)
255
256 def characters(self, data):
257 global log
258 log = log + &quot;characters: %s:&quot; % (data)
259
260 def warning(self, msg):
261 global log
262 log = log + &quot;warning: %s:&quot; % (msg)
263
264 def error(self, msg):
265 global log
266 log = log + &quot;error: %s:&quot; % (msg)
267
268 def fatalError(self, msg):
269 global log
270 log = log + &quot;fatalError: %s:&quot; % (msg)
271
272handler = callback()
273
274ctxt = libxml2.createPushParser(handler, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
275chunk = &quot; url='tst'&gt;b&quot;
276ctxt.parseChunk(chunk, len(chunk), 0)
277chunk = &quot;ar&lt;/foo&gt;&quot;
278ctxt.parseChunk(chunk, len(chunk), 1)
279
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +0000[diff] [blame]280reference = &quot;startDocument:startElement foo {'url': 'tst'}:&quot; + \
281 &quot;characters: bar:endElement foo:endDocument:&quot;
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]282if log != reference:
283 print &quot;Error got: %s&quot; % log
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]284 print &quot;Expected: %s&quot; % reference</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]285<p>The key object in that test is the handler, it provides a number of entry
286points which can be called by the parser as it makes progresses to indicate
287the information set obtained. The full set of callback is larger than what
288the callback class in that specific example implements (see the SAX
289definition for a complete list). The wrapper will only call those supplied by
290the object when activated. The startElement receives the names of the element
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]291and a dictionary containing the attributes carried by this element.</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]292<p>Also note that the reference string generated from the callback shows a
293single character call even though the string &quot;bar&quot; is passed to the parser
294from 2 different call to parseChunk()</p>
295<h3>xpath.py:</h3>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]296<p>This is a basic test of XPath wrappers support</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]297<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]298
299doc = libxml2.parseFile(&quot;tst.xml&quot;)
300ctxt = doc.xpathNewContext()
301res = ctxt.xpathEval(&quot;//*&quot;)
302if len(res) != 2:
303 print &quot;xpath query: wrong node set size&quot;
304 sys.exit(1)
305if res[0].name != &quot;doc&quot; or res[1].name != &quot;foo&quot;:
306 print &quot;xpath query: wrong node set value&quot;
307 sys.exit(1)
308doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]309ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]310<p>This test parses a file, then create an XPath context to evaluate XPath
311expression on it. The xpathEval() method execute an XPath query and returns
312the result mapped in a Python way. String and numbers are natively converted,
313and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]314the document, the XPath context need to be freed explicitly, also not that
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]315the result of the XPath query may point back to the document tree and hence
316the document must be freed after the result of the query is used.</p>
317<h3>xpathext.py:</h3>
318<p>This test shows how to extend the XPath engine with functions written in
319python:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]320<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]321
322def foo(ctx, x):
323 return x + 1
324
325doc = libxml2.parseFile(&quot;tst.xml&quot;)
326ctxt = doc.xpathNewContext()
327libxml2.registerXPathFunction(ctxt._o, &quot;foo&quot;, None, foo)
328res = ctxt.xpathEval(&quot;foo(1)&quot;)
329if res != 2:
330 print &quot;xpath extension failure&quot;
331doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]332ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]333<p>Note how the extension function is registered with the context (but that
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]334part is not yet finalized, this may change slightly in the future).</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]335<h3>tstxpath.py:</h3>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]336<p>This test is similar to the previous one but shows how the extension
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]337function can access the XPath evaluation context:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]338<pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]339 global called
340
341 #
342 # test that access to the XPath evaluation contexts
343 #
344 pctxt = libxml2.xpathParserContext(_obj=ctx)
345 ctxt = pctxt.context()
346 called = ctxt.function()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]347 return x + 1</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]348<p>All the interfaces around the XPath parser(or rather evaluation) context
349are not finalized, but it should be sufficient to do contextual work at the
350evaluation point.</p>
351<h3>Memory debugging:</h3>
352<p>last but not least, all tests starts with the following prologue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]353<pre>#memory debug specific
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]354libxml2.debugMemory(1)</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]355<p>and ends with the following epilogue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]356<pre>#memory debug specific
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]357libxml2.cleanupParser()
358if libxml2.debugMemory(1) == 0:
359 print &quot;OK&quot;
360else:
361 print &quot;Memory leak %d bytes&quot; % (libxml2.debugMemory(1))
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]362 libxml2.dumpMemory()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]363<p>Those activate the memory debugging interface of libxml2 where all
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]364allocated block in the library are tracked. The prologue then cleans up the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]365library state and checks that all allocated memory has been freed. If not it
366calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
367<p><a href="bugs.html">Daniel Veillard</a></p>
368</td></tr></table></td></tr></table></td></tr></table></td>
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