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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>
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>
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>
48<li><a href="interface.html">The SAX interface</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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54<li><a href="library.html">The parser interfaces</a></li>
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>
69</td></tr>
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
136 an effort to create a 100% JAXP-compatible Java wrapper for
137 libxml2 and libxslt as part of GNU ClasspathX project.
138</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]139</ul>
Daniel Veillardc0801af2002-05-28 16:28:42 +0000[diff] [blame]140<p>The distribution includes a set of Python bindings, which are guaranteed
141to be maintained as part of the library in the future, though the Python
Daniel Veillard41b01a82003-02-27 11:09:06 +0000[diff] [blame^]142interface have not yet reached the completeness of the C API.</p>
Daniel Veillard27907c72002-12-16 16:05:58 +0000[diff] [blame]143<p>
144<a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
Daniel Veillard7b4b2f92003-01-06 13:11:20 +0000[diff] [blame]145maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
146of the Python bindings</a>.</p>
Daniel Veillard7ef0fcb2002-12-14 10:38:55 +0000[diff] [blame]147<p>Note to people interested in building bindings, the API is formalized as
148<a href="libxml2-api.xml">an XML API description file</a> which allows to
149automate a large part of the Python bindings, this includes function
Daniel Veillard7b4b2f92003-01-06 13:11:20 +0000[diff] [blame]150descriptions, enums, structures, typedefs, etc... The Python script used to
151build the bindings is python/generator.py in the source distribution.</p>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]152<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]153<ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]154<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
155 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
156 RPM</a>).</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]157 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]158 module distribution</a> corresponding to your installed version of
159 libxml2 and libxslt. Note that to install it you will need both libxml2
160 and libxslt installed and run &quot;python setup.py build install&quot; in the
161 module tree.</li>
Daniel Veillard0b79dfe2002-02-23 13:02:31 +0000[diff] [blame]162</ul>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]163<p>The distribution includes a set of examples and regression tests for the
164python bindings in the <code>python/tests</code> directory. Here are some
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]165excerpts from those tests:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]166<h3>tst.py:</h3>
167<p>This is a basic test of the file interface and DOM navigation:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]168<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]169
170doc = libxml2.parseFile(&quot;tst.xml&quot;)
171if doc.name != &quot;tst.xml&quot;:
172 print &quot;doc.name failed&quot;
173 sys.exit(1)
174root = doc.children
175if root.name != &quot;doc&quot;:
176 print &quot;root.name failed&quot;
177 sys.exit(1)
178child = root.children
179if child.name != &quot;foo&quot;:
180 print &quot;child.name failed&quot;
181 sys.exit(1)
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]182doc.freeDoc()</pre>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]183<p>The Python module is called libxml2; parseFile is the equivalent of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]184xmlParseFile (most of the bindings are automatically generated, and the xml
185prefix is removed and the casing convention are kept). All node seen at the
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]186binding level share the same subset of accessors:</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]187<ul>
188<li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]189<code>name</code> : returns the node name</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]190 <li>
Daniel Veillardc0801af2002-05-28 16:28:42 +0000[diff] [blame]191<code>type</code> : returns a string indicating the node type</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]192 <li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]193<code>content</code> : returns the content of the node, it is based on
194 xmlNodeGetContent() and hence is recursive.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]195 <li>
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]196<code>parent</code> , <code>children</code>, <code>last</code>,
197 <code>next</code>, <code>prev</code>, <code>doc</code>,
198 <code>properties</code>: pointing to the associated element in the tree,
199 those may return None in case no such link exists.</li>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]200</ul>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]201<p>Also note the need to explicitly deallocate documents with freeDoc() .
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]202Reference counting for libxml2 trees would need quite a lot of work to
203function properly, and rather than risk memory leaks if not implemented
204correctly it sounds safer to have an explicit function to free a tree. The
205wrapper python objects like doc, root or child are them automatically garbage
206collected.</p>
207<h3>validate.py:</h3>
208<p>This test check the validation interfaces and redirection of error
209messages:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]210<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]211
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]212#deactivate error messages from the validation
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]213def noerr(ctx, str):
214 pass
215
216libxml2.registerErrorHandler(noerr, None)
217
218ctxt = libxml2.createFileParserCtxt(&quot;invalid.xml&quot;)
219ctxt.validate(1)
220ctxt.parseDocument()
221doc = ctxt.doc()
222valid = ctxt.isValid()
223doc.freeDoc()
224if valid != 0:
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]225 print &quot;validity check failed&quot;</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]226<p>The first thing to notice is the call to registerErrorHandler(), it
227defines a new error handler global to the library. It is used to avoid seeing
228the error messages when trying to validate the invalid document.</p>
229<p>The main interest of that test is the creation of a parser context with
230createFileParserCtxt() and how the behaviour can be changed before calling
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]231parseDocument() . Similarly the informations resulting from the parsing phase
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]232are also available using context methods.</p>
233<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
234C function interfaces in terms of objects method as much as possible. The
235best to get a complete view of what methods are supported is to look at the
236libxml2.py module containing all the wrappers.</p>
237<h3>push.py:</h3>
238<p>This test show how to activate the push parser interface:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]239<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]240
241ctxt = libxml2.createPushParser(None, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
242ctxt.parseChunk(&quot;/&gt;&quot;, 2, 1)
243doc = ctxt.doc()
244
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]245doc.freeDoc()</pre>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]246<p>The context is created with a special call based on the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]247xmlCreatePushParser() from the C library. The first argument is an optional
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]248SAX callback object, then the initial set of data, the length and the name of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]249the resource in case URI-References need to be computed by the parser.</p>
250<p>Then the data are pushed using the parseChunk() method, the last call
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]251setting the third argument terminate to 1.</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]252<h3>pushSAX.py:</h3>
253<p>this test show the use of the event based parsing interfaces. In this case
254the parser does not build a document, but provides callback information as
255the parser makes progresses analyzing the data being provided:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]256<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]257log = &quot;&quot;
258
259class callback:
260 def startDocument(self):
261 global log
262 log = log + &quot;startDocument:&quot;
263
264 def endDocument(self):
265 global log
266 log = log + &quot;endDocument:&quot;
267
268 def startElement(self, tag, attrs):
269 global log
270 log = log + &quot;startElement %s %s:&quot; % (tag, attrs)
271
272 def endElement(self, tag):
273 global log
274 log = log + &quot;endElement %s:&quot; % (tag)
275
276 def characters(self, data):
277 global log
278 log = log + &quot;characters: %s:&quot; % (data)
279
280 def warning(self, msg):
281 global log
282 log = log + &quot;warning: %s:&quot; % (msg)
283
284 def error(self, msg):
285 global log
286 log = log + &quot;error: %s:&quot; % (msg)
287
288 def fatalError(self, msg):
289 global log
290 log = log + &quot;fatalError: %s:&quot; % (msg)
291
292handler = callback()
293
294ctxt = libxml2.createPushParser(handler, &quot;&lt;foo&quot;, 4, &quot;test.xml&quot;)
295chunk = &quot; url='tst'&gt;b&quot;
296ctxt.parseChunk(chunk, len(chunk), 0)
297chunk = &quot;ar&lt;/foo&gt;&quot;
298ctxt.parseChunk(chunk, len(chunk), 1)
299
Daniel Veillardfcbfa2d2002-02-21 17:54:27 +0000[diff] [blame]300reference = &quot;startDocument:startElement foo {'url': 'tst'}:&quot; + \
301 &quot;characters: bar:endElement foo:endDocument:&quot;
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]302if log != reference:
303 print &quot;Error got: %s&quot; % log
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]304 print &quot;Expected: %s&quot; % reference</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]305<p>The key object in that test is the handler, it provides a number of entry
306points which can be called by the parser as it makes progresses to indicate
307the information set obtained. The full set of callback is larger than what
308the callback class in that specific example implements (see the SAX
309definition for a complete list). The wrapper will only call those supplied by
310the object when activated. The startElement receives the names of the element
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]311and a dictionary containing the attributes carried by this element.</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]312<p>Also note that the reference string generated from the callback shows a
313single character call even though the string &quot;bar&quot; is passed to the parser
314from 2 different call to parseChunk()</p>
315<h3>xpath.py:</h3>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]316<p>This is a basic test of XPath wrappers support</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]317<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]318
319doc = libxml2.parseFile(&quot;tst.xml&quot;)
320ctxt = doc.xpathNewContext()
321res = ctxt.xpathEval(&quot;//*&quot;)
322if len(res) != 2:
323 print &quot;xpath query: wrong node set size&quot;
324 sys.exit(1)
325if res[0].name != &quot;doc&quot; or res[1].name != &quot;foo&quot;:
326 print &quot;xpath query: wrong node set value&quot;
327 sys.exit(1)
328doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]329ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]330<p>This test parses a file, then create an XPath context to evaluate XPath
331expression on it. The xpathEval() method execute an XPath query and returns
332the result mapped in a Python way. String and numbers are natively converted,
333and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]334the document, the XPath context need to be freed explicitly, also not that
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]335the result of the XPath query may point back to the document tree and hence
336the document must be freed after the result of the query is used.</p>
337<h3>xpathext.py:</h3>
338<p>This test shows how to extend the XPath engine with functions written in
339python:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]340<pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]341
342def foo(ctx, x):
343 return x + 1
344
345doc = libxml2.parseFile(&quot;tst.xml&quot;)
346ctxt = doc.xpathNewContext()
347libxml2.registerXPathFunction(ctxt._o, &quot;foo&quot;, None, foo)
348res = ctxt.xpathEval(&quot;foo(1)&quot;)
349if res != 2:
350 print &quot;xpath extension failure&quot;
351doc.freeDoc()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]352ctxt.xpathFreeContext()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]353<p>Note how the extension function is registered with the context (but that
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]354part is not yet finalized, this may change slightly in the future).</p>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]355<h3>tstxpath.py:</h3>
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]356<p>This test is similar to the previous one but shows how the extension
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]357function can access the XPath evaluation context:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]358<pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]359 global called
360
361 #
362 # test that access to the XPath evaluation contexts
363 #
364 pctxt = libxml2.xpathParserContext(_obj=ctx)
365 ctxt = pctxt.context()
366 called = ctxt.function()
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]367 return x + 1</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]368<p>All the interfaces around the XPath parser(or rather evaluation) context
369are not finalized, but it should be sufficient to do contextual work at the
370evaluation point.</p>
371<h3>Memory debugging:</h3>
372<p>last but not least, all tests starts with the following prologue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]373<pre>#memory debug specific
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]374libxml2.debugMemory(1)</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]375<p>and ends with the following epilogue:</p>
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]376<pre>#memory debug specific
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]377libxml2.cleanupParser()
378if libxml2.debugMemory(1) == 0:
379 print &quot;OK&quot;
380else:
381 print &quot;Memory leak %d bytes&quot; % (libxml2.debugMemory(1))
Daniel Veillard9eb146b2002-02-21 16:04:51 +0000[diff] [blame]382 libxml2.dumpMemory()</pre>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]383<p>Those activate the memory debugging interface of libxml2 where all
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]384allocated block in the library are tracked. The prologue then cleans up the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]385library state and checks that all allocated memory has been freed. If not it
386calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
387<p><a href="bugs.html">Daniel Veillard</a></p>
388</td></tr></table></td></tr></table></td></tr></table></td>
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