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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>
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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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29<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Main Menu</b></center></td></tr>
Daniel Veillard4a603e42003-01-11 14:18:53 +0000[diff] [blame]30<tr><td bgcolor="#fffacd">
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Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]35<li><a href="index.html">Home</a></li>
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46<li><a href="architecture.html">libxml architecture</a></li>
47<li><a href="tree.html">The tree output</a></li>
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50<li><a href="xmlmem.html">Memory Management</a></li>
51<li><a href="encoding.html">Encodings support</a></li>
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55<li><a href="entities.html">Entities or no entities</a></li>
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57<li><a href="upgrade.html">Upgrading 1.x code</a></li>
58<li><a href="threads.html">Thread safety</a></li>
59<li><a href="DOM.html">DOM Principles</a></li>
60<li><a href="example.html">A real example</a></li>
61<li><a href="contribs.html">Contributions</a></li>
Daniel Veillard7b4b2f92003-01-06 13:11:20 +0000[diff] [blame]62<li><a href="xmlreader.html">The Reader Interface</a></li>
Daniel Veillardfc59c092002-06-05 14:48:26 +0000[diff] [blame]63<li><a href="tutorial/index.html">Tutorial</a></li>
Daniel Veillard7b4b2f92003-01-06 13:11:20 +0000[diff] [blame]64<li><a href="guidelines.html">XML Guidelines</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]65<li>
66<a href="xml.html">flat page</a>, <a href="site.xsl">stylesheet</a>
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Daniel Veillard5ede35e2002-10-01 11:37:35 +0000[diff] [blame]68</ul>
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Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]70</table>
71<table width="100%" border="0" cellspacing="1" cellpadding="3">
72<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr>
73<tr><td bgcolor="#fffacd"><ul>
74<li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li>
75<li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li>
76<li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]77<li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]78<li><a href="ftp://xmlsoft.org/">FTP</a></li>
Daniel Veillardc84f8b52002-12-19 22:12:47 +0000[diff] [blame]79<li><a href="http://www.zlatkovic.com/projects/libxml/">Windows binaries</a></li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]80<li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
Daniel Veillardcb7543b2002-09-09 10:54:06 +0000[diff] [blame]81<li><a href="http://www.zveno.com/open_source/libxml2xslt.html">MacOsX binaries</a></li>
Daniel Veillarde6d8e202002-05-02 06:11:10 +0000[diff] [blame]82<li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li>
Daniel Veillard2d347fa2002-03-17 10:34:11 +0000[diff] [blame]83<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]84</ul></td></tr>
85</table>
Daniel Veillard4a603e42003-01-11 14:18:53 +0000[diff] [blame]86<table width="100%" border="0" cellspacing="1" cellpadding="3">
87<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr>
88<tr><td bgcolor="#fffacd"><ul>
89<li><a href="APIchunk0.html">Alphabetic</a></li>
90<li><a href="APIconstructors.html">Constructors</a></li>
91<li><a href="APIfunctions.html">Functions/Types</a></li>
92<li><a href="APIfiles.html">Modules</a></li>
93<li><a href="APIsymbols.html">Symbols</a></li>
94</ul></td></tr>
95</table>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]96</td></tr></table></td>
97<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]98<p>There are a number of language bindings and wrappers available for
99libxml2, 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]100(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
101order to get updates to this list or to discuss the specific topic of libxml2
102or libxslt wrappers or bindings:</p>
103<ul>
104<li>
Daniel Veillardc14401e2002-11-20 14:28:17 +0000[diff] [blame]105<a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the
106 most up-to-date C++ bindings for libxml2, check the <a href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a>
107 and the <a href="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libxmlplusplus/libxml%2b%2b/examples/">examples</a>.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]108 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
109 based on the gdome2 bindings</a> maintained by Tobias Peters.</li>
110 <li>and a third C++ wrapper by Peter Jones &lt;pjones@pmade.org&gt;
Daniel Veillard9b6fd302002-05-13 12:06:47 +0000[diff] [blame]111 <p>Website: <a href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a>
112</p>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]113 </li>
114 <li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]115<a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]116 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]117 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]118 application server</a>.</li>
119 <li>
Daniel Veillard21473672002-06-17 07:29:22 +0000[diff] [blame]120<a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]121 earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li>
122 <li>Gopal.V and Peter Minten develop <a href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of
123 C# libxml2 bindings.</li>
124 <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
125 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li>
126 <li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2
127 implementation for Kylix2/D5/D6 from Borland.</li>
128 <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]129 libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
130 maintained by Tobias Peters.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]131 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
132 Tcl</a>.</li>
133 <li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard41b01a82003-02-27 11:09:06 +0000[diff] [blame]134 <li>
135<a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is
Daniel Veillard806cada2003-03-19 21:58:59 +0000[diff] [blame^]136 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and
137 libxslt as part of GNU ClasspathX project.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]138</ul>
Daniel Veillardc0801af2002-05-28 16:28:42 +0000[diff] [blame]139<p>The distribution includes a set of Python bindings, which are guaranteed
140to be maintained as part of the library in the future, though the Python
Daniel Veillard41b01a82003-02-27 11:09:06 +0000[diff] [blame]141interface have not yet reached the completeness of the C API.</p>
Daniel Veillard27907c72002-12-16 16:05:58 +0000[diff] [blame]142<p>
143<a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
Daniel Veillard7b4b2f92003-01-06 13:11:20 +0000[diff] [blame]144maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
145of the Python bindings</a>.</p>
Daniel Veillard7ef0fcb2002-12-14 10:38:55 +0000[diff] [blame]146<p>Note to people interested in building bindings, the API is formalized as
147<a href="libxml2-api.xml">an XML API description file</a> which allows to
148automate a large part of the Python bindings, this includes function
Daniel Veillard7b4b2f92003-01-06 13:11:20 +0000[diff] [blame]149descriptions, enums, structures, typedefs, etc... The Python script used to
150build the bindings is python/generator.py in the source distribution.</p>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]151<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]152<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]153<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
154 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
155 RPM</a>).</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]156 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]157 module distribution</a> corresponding to your installed version of
158 libxml2 and libxslt. Note that to install it you will need both libxml2
159 and libxslt installed and run &quot;python setup.py build install&quot; in the
160 module tree.</li>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]161</ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]162<p>The distribution includes a set of examples and regression tests for the
163python bindings in the <code>python/tests</code> directory. Here are some
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]164excerpts from those tests:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]165<h3>tst.py:</h3>
166<p>This is a basic test of the file interface and DOM navigation:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]167<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]168
169doc = libxml2.parseFile(&quot;tst.xml&quot;)
170if doc.name != &quot;tst.xml&quot;:
171 print &quot;doc.name failed&quot;
172 sys.exit(1)
173root = doc.children
174if root.name != &quot;doc&quot;:
175 print &quot;root.name failed&quot;
176 sys.exit(1)
177child = root.children
178if child.name != &quot;foo&quot;:
179 print &quot;child.name failed&quot;
180 sys.exit(1)
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]181doc.freeDoc()</pre>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]182<p>The Python module is called libxml2; parseFile is the equivalent of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]183xmlParseFile (most of the bindings are automatically generated, and the xml
184prefix is removed and the casing convention are kept). All node seen at the
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]185binding level share the same subset of accessors:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]186<ul>
187<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]188<code>name</code> : returns the node name</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]189 <li>
Daniel Veillardc0801af2002-05-28 16:28:42 +0000[diff] [blame]190<code>type</code> : returns a string indicating the node type</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]191 <li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]192<code>content</code> : returns the content of the node, it is based on
193 xmlNodeGetContent() and hence is recursive.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]194 <li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]195<code>parent</code> , <code>children</code>, <code>last</code>,
196 <code>next</code>, <code>prev</code>, <code>doc</code>,
197 <code>properties</code>: pointing to the associated element in the tree,
198 those may return None in case no such link exists.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]199</ul>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]200<p>Also note the need to explicitly deallocate documents with freeDoc() .
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]201Reference counting for libxml2 trees would need quite a lot of work to
202function properly, and rather than risk memory leaks if not implemented
203correctly it sounds safer to have an explicit function to free a tree. The
204wrapper python objects like doc, root or child are them automatically garbage
205collected.</p>
206<h3>validate.py:</h3>
207<p>This test check the validation interfaces and redirection of error
208messages:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]209<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]210
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]211#deactivate error messages from the validation
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]212def noerr(ctx, str):
213 pass
214
215libxml2.registerErrorHandler(noerr, None)
216
217ctxt = libxml2.createFileParserCtxt(&quot;invalid.xml&quot;)
218ctxt.validate(1)
219ctxt.parseDocument()
220doc = ctxt.doc()
221valid = ctxt.isValid()
222doc.freeDoc()
223if valid != 0:
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]224 print &quot;validity check failed&quot;</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]225<p>The first thing to notice is the call to registerErrorHandler(), it
226defines a new error handler global to the library. It is used to avoid seeing
227the error messages when trying to validate the invalid document.</p>
228<p>The main interest of that test is the creation of a parser context with
229createFileParserCtxt() and how the behaviour can be changed before calling
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]230parseDocument() . Similarly the informations resulting from the parsing phase
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]231are also available using context methods.</p>
232<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
233C function interfaces in terms of objects method as much as possible. The
234best to get a complete view of what methods are supported is to look at the
235libxml2.py module containing all the wrappers.</p>
236<h3>push.py:</h3>
237<p>This test show how to activate the push parser interface:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]238<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]239
240ctxt = libxml2.createPushParser(None, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
241ctxt.parseChunk(&quot;/&gt;&quot;, 2, 1)
242doc = ctxt.doc()
243
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]244doc.freeDoc()</pre>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]245<p>The context is created with a special call based on the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]246xmlCreatePushParser() from the C library. The first argument is an optional
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]247SAX callback object, then the initial set of data, the length and the name of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]248the resource in case URI-References need to be computed by the parser.</p>
249<p>Then the data are pushed using the parseChunk() method, the last call
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]250setting the third argument terminate to 1.</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]251<h3>pushSAX.py:</h3>
252<p>this test show the use of the event based parsing interfaces. In this case
253the parser does not build a document, but provides callback information as
254the parser makes progresses analyzing the data being provided:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]255<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]256log = &quot;&quot;
257
258class callback:
259 def startDocument(self):
260 global log
261 log = log + &quot;startDocument:&quot;
262
263 def endDocument(self):
264 global log
265 log = log + &quot;endDocument:&quot;
266
267 def startElement(self, tag, attrs):
268 global log
269 log = log + &quot;startElement %s %s:&quot; % (tag, attrs)
270
271 def endElement(self, tag):
272 global log
273 log = log + &quot;endElement %s:&quot; % (tag)
274
275 def characters(self, data):
276 global log
277 log = log + &quot;characters: %s:&quot; % (data)
278
279 def warning(self, msg):
280 global log
281 log = log + &quot;warning: %s:&quot; % (msg)
282
283 def error(self, msg):
284 global log
285 log = log + &quot;error: %s:&quot; % (msg)
286
287 def fatalError(self, msg):
288 global log
289 log = log + &quot;fatalError: %s:&quot; % (msg)
290
291handler = callback()
292
293ctxt = libxml2.createPushParser(handler, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
294chunk = &quot; url='tst'&gt;b&quot;
295ctxt.parseChunk(chunk, len(chunk), 0)
296chunk = &quot;ar&lt;/foo&gt;&quot;
297ctxt.parseChunk(chunk, len(chunk), 1)
298
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +0000[diff] [blame]299reference = &quot;startDocument:startElement foo {'url': 'tst'}:&quot; + \
300 &quot;characters: bar:endElement foo:endDocument:&quot;
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]301if log != reference:
302 print &quot;Error got: %s&quot; % log
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]303 print &quot;Expected: %s&quot; % reference</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]304<p>The key object in that test is the handler, it provides a number of entry
305points which can be called by the parser as it makes progresses to indicate
306the information set obtained. The full set of callback is larger than what
307the callback class in that specific example implements (see the SAX
308definition for a complete list). The wrapper will only call those supplied by
309the object when activated. The startElement receives the names of the element
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]310and a dictionary containing the attributes carried by this element.</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]311<p>Also note that the reference string generated from the callback shows a
312single character call even though the string &quot;bar&quot; is passed to the parser
313from 2 different call to parseChunk()</p>
314<h3>xpath.py:</h3>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]315<p>This is a basic test of XPath wrappers support</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]316<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]317
318doc = libxml2.parseFile(&quot;tst.xml&quot;)
319ctxt = doc.xpathNewContext()
320res = ctxt.xpathEval(&quot;//*&quot;)
321if len(res) != 2:
322 print &quot;xpath query: wrong node set size&quot;
323 sys.exit(1)
324if res[0].name != &quot;doc&quot; or res[1].name != &quot;foo&quot;:
325 print &quot;xpath query: wrong node set value&quot;
326 sys.exit(1)
327doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]328ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]329<p>This test parses a file, then create an XPath context to evaluate XPath
330expression on it. The xpathEval() method execute an XPath query and returns
331the result mapped in a Python way. String and numbers are natively converted,
332and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]333the document, the XPath context need to be freed explicitly, also not that
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]334the result of the XPath query may point back to the document tree and hence
335the document must be freed after the result of the query is used.</p>
336<h3>xpathext.py:</h3>
337<p>This test shows how to extend the XPath engine with functions written in
338python:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]339<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]340
341def foo(ctx, x):
342 return x + 1
343
344doc = libxml2.parseFile(&quot;tst.xml&quot;)
345ctxt = doc.xpathNewContext()
346libxml2.registerXPathFunction(ctxt._o, &quot;foo&quot;, None, foo)
347res = ctxt.xpathEval(&quot;foo(1)&quot;)
348if res != 2:
349 print &quot;xpath extension failure&quot;
350doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]351ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]352<p>Note how the extension function is registered with the context (but that
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]353part is not yet finalized, this may change slightly in the future).</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]354<h3>tstxpath.py:</h3>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]355<p>This test is similar to the previous one but shows how the extension
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]356function can access the XPath evaluation context:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]357<pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]358 global called
359
360 #
361 # test that access to the XPath evaluation contexts
362 #
363 pctxt = libxml2.xpathParserContext(_obj=ctx)
364 ctxt = pctxt.context()
365 called = ctxt.function()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]366 return x + 1</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]367<p>All the interfaces around the XPath parser(or rather evaluation) context
368are not finalized, but it should be sufficient to do contextual work at the
369evaluation point.</p>
370<h3>Memory debugging:</h3>
371<p>last but not least, all tests starts with the following prologue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]372<pre>#memory debug specific
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]373libxml2.debugMemory(1)</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]374<p>and ends with the following epilogue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]375<pre>#memory debug specific
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]376libxml2.cleanupParser()
377if libxml2.debugMemory(1) == 0:
378 print &quot;OK&quot;
379else:
380 print &quot;Memory leak %d bytes&quot; % (libxml2.debugMemory(1))
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]381 libxml2.dumpMemory()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]382<p>Those activate the memory debugging interface of libxml2 where all
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]383allocated block in the library are tracked. The prologue then cleans up the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]384library state and checks that all allocated memory has been freed. If not it
385calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
386<p><a href="bugs.html">Daniel Veillard</a></p>
387</td></tr></table></td></tr></table></td></tr></table></td>
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