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Daniel Veillardd49370e2005-04-11 23:28:16 +000010</style><title>Python and bindings</title></head><body bgcolor="#8b7765" text="#000000" link="#a06060" vlink="#000000"><table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr><td width="120"><a href="http://swpat.ffii.org/"><img src="epatents.png" alt="Action against software patents" /></a></td><td width="180"><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></td><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"><h1>The XML C parser and toolkit of Gnome</h1><h2>Python and bindings</h2></td></tr></table></td></tr></table></td></tr></table><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><td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Developer Menu</b></center></td></tr><tr><td bgcolor="#fffacd"><form action="search.php" enctype="application/x-www-form-urlencoded" method="get"><input name="query" type="text" size="20" value="" /><input name="submit" type="submit" value="Search ..." /></form><ul><li><a href="index.html" style="font-weight:bold">Main Menu</a></li><li><a href="html/index.html" style="font-weight:bold">Reference Manual</a></li><li><a href="examples/index.html" style="font-weight:bold">Code Examples</a></li><li><a href="guidelines.html">XML Guidelines</a></li><li><a href="tutorial/index.html">Tutorial</a></li><li><a href="xmlreader.html">The Reader Interface</a></li><li><a href="ChangeLog.html">ChangeLog</a></li><li><a href="XSLT.html">XSLT</a></li><li><a href="python.html">Python and bindings</a></li><li><a href="architecture.html">libxml2 architecture</a></li><li><a href="tree.html">The tree output</a></li><li><a href="interface.html">The SAX interface</a></li><li><a href="xmlmem.html">Memory Management</a></li><li><a href="xmlio.html">I/O Interfaces</a></li><li><a href="library.html">The parser interfaces</a></li><li><a href="entities.html">Entities or no entities</a></li><li><a href="namespaces.html">Namespaces</a></li><li><a href="upgrade.html">Upgrading 1.x code</a></li><li><a href="threads.html">Thread safety</a></li><li><a href="DOM.html">DOM Principles</a></li><li><a href="example.html">A real example</a></li><li><a href="xml.html">flat page</a>, <a href="site.xsl">stylesheet</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="APIchunk0.html">Alphabetic</a></li><li><a href="APIconstructors.html">Constructors</a></li><li><a href="APIfunctions.html">Functions/Types</a></li><li><a href="APIfiles.html">Modules</a></li><li><a href="APIsymbols.html">Symbols</a></li></ul></td></tr></table><table width="100%" border="0" cellspacing="1" cellpadding="3"><tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr><tr><td bgcolor="#fffacd"><ul><li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li><li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li><li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li><li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li><li><a href="ftp://xmlsoft.org/">FTP</a></li><li><a href="http://www.zlatkovic.com/projects/libxml/">Windows binaries</a></li><li><a href="http://www.blastwave.org/packages.php/libxml2">Solaris binaries</a></li><li><a href="http://www.explain.com.au/oss/libxml2xslt.html">MacOsX binaries</a></li><li><a href="http://libxmlplusplus.sourceforge.net/">C++ bindings</a></li><li><a href="http://www.zend.com/php5/articles/php5-xmlphp.php#Heading4">PHP bindings</a></li><li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li><li><a href="http://rubyforge.org/projects/xml-tools/">Ruby bindings</a></li><li><a href="http://tclxml.sourceforge.net/">Tcl bindings</a></li><li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml2">Bug Tracker</a></li></ul></td></tr></table></td></tr></table></td><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"><p>There are a number of language bindings and wrappers available for
Daniel Veillard42766c02002-08-22 20:52:17 +000011libxml2, 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 +000012(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
13order to get updates to this list or to discuss the specific topic of libxml2
Daniel Veillard1177ca42003-04-26 22:29:54 +000014or libxslt wrappers or bindings:</p><ul><li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the
Daniel Veillardc14401e2002-11-20 14:28:17 +000015 most up-to-date C++ bindings for libxml2, check the <a href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a>
16 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 +000017 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
18 based on the gdome2 bindings</a> maintained by Tobias Peters.</li>
19 <li>and a third C++ wrapper by Peter Jones &lt;pjones@pmade.org&gt;
Daniel Veillard1177ca42003-04-26 22:29:54 +000020 <p>Website: <a href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p>
Daniel Veillard0b28e882002-07-24 23:47:05 +000021 </li>
Daniel Veillard1177ca42003-04-26 22:29:54 +000022 <li><a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard63d83142002-05-20 06:51:05 +000023 Sergeant</a> developed <a href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper for
Daniel Veillardaf43f632002-03-08 15:05:20 +000024 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
Daniel Veillard0b28e882002-07-24 23:47:05 +000025 application server</a>.</li>
Daniel Veillard4ac494b2003-09-18 15:08:00 +000026 <li>If you're interested into scripting XML processing, have a look at <a href="http://xsh.sourceforge.net/">XSH</a> an XML editing shell based on
27 Libxml2 Perl bindings.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +000028 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an
Daniel Veillard0b28e882002-07-24 23:47:05 +000029 earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li>
30 <li>Gopal.V and Peter Minten develop <a href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of
31 C# libxml2 bindings.</li>
32 <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
33 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li>
34 <li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2
35 implementation for Kylix2/D5/D6 from Borland.</li>
Daniel Veillard142fb212005-04-07 12:48:10 +000036 <li>There is <a href="http://rubyforge.org/projects/xml-tools/">bindings for Ruby</a> and
Daniel Veillard6dbcaf82002-02-20 14:37:47 +000037 libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
38 maintained by Tobias Peters.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +000039 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
40 Tcl</a>.</li>
Daniel Veillard142fb212005-04-07 12:48:10 +000041 <li>libxml2 and libxslt is the default XML library for PHP5.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +000042 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is
Daniel Veillard806cada2003-03-19 21:58:59 +000043 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and
44 libxslt as part of GNU ClasspathX project.</li>
Daniel Veillard6d373a22003-11-04 10:26:43 +000045 <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt, look for
46 <a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.</li>
Daniel Veillardb78757b2004-12-30 21:30:23 +000047 <li><a href="http://www.satimage.fr/software/en/xml_suite.html">Satimage</a>
48 provides <a href="http://www.satimage.fr/software/en/downloads_osaxen.html">XMLLib
49 osax</a>. This is an osax for Mac OS X with a set of commands to
50 implement in AppleScript the XML DOM, XPATH and XSLT. Also includes
Daniel Veillardc7426092005-01-05 15:11:41 +000051 commands for Property-lists (Apple's fast lookup table XML format.)</li>
52 <li>Francesco Montorsi developped
53<a href="https://sourceforge.net/project/showfiles.php?group_id=51305&amp;package_id=45182">wxXml2</a>
54 wrappers that interface libxml2, allowing wxWidgets applications to
55 load/save/edit XML instances.</li>
56</ul><p>The distribution includes a set of Python bindings, which are guaranteed
Daniel Veillardc0801af2002-05-28 16:28:42 +000057to be maintained as part of the library in the future, though the Python
Daniel Veillard1177ca42003-04-26 22:29:54 +000058interface have not yet reached the completeness of the C API.</p><p><a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
Daniel Veillard7b4b2f92003-01-06 13:11:20 +000059maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
Daniel Veillard1177ca42003-04-26 22:29:54 +000060of the Python bindings</a>.</p><p>Note to people interested in building bindings, the API is formalized as
Daniel Veillard7ef0fcb2002-12-14 10:38:55 +000061<a href="libxml2-api.xml">an XML API description file</a> which allows to
62automate a large part of the Python bindings, this includes function
Daniel Veillard7b4b2f92003-01-06 13:11:20 +000063descriptions, enums, structures, typedefs, etc... The Python script used to
Daniel Veillard1177ca42003-04-26 22:29:54 +000064build the bindings is python/generator.py in the source distribution.</p><p>To install the Python bindings there are 2 options:</p><ul><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
Daniel Veillardaf43f632002-03-08 15:05:20 +000065 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
66 RPM</a>).</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +000067 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
Daniel Veillardaf43f632002-03-08 15:05:20 +000068 module distribution</a> corresponding to your installed version of
69 libxml2 and libxslt. Note that to install it you will need both libxml2
Daniel Veillard024f1992003-12-10 16:43:49 +000070 and libxslt installed and run "python setup.py build install" in the
Daniel Veillardaf43f632002-03-08 15:05:20 +000071 module tree.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +000072</ul><p>The distribution includes a set of examples and regression tests for the
Daniel Veillardaf43f632002-03-08 15:05:20 +000073python bindings in the <code>python/tests</code> directory. Here are some
MST 2003 John Fleck2dffb762003-11-29 04:41:24 +000074excerpts from those tests:</p><h3>tst.py:</h3><p>This is a basic test of the file interface and DOM navigation:</p><pre>import libxml2, sys
Daniel Veillard6dbcaf82002-02-20 14:37:47 +000075
Daniel Veillard024f1992003-12-10 16:43:49 +000076doc = libxml2.parseFile("tst.xml")
77if doc.name != "tst.xml":
78 print "doc.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +000079 sys.exit(1)
80root = doc.children
Daniel Veillard024f1992003-12-10 16:43:49 +000081if root.name != "doc":
82 print "root.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +000083 sys.exit(1)
84child = root.children
Daniel Veillard024f1992003-12-10 16:43:49 +000085if child.name != "foo":
86 print "child.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +000087 sys.exit(1)
Daniel Veillard1177ca42003-04-26 22:29:54 +000088doc.freeDoc()</pre><p>The Python module is called libxml2; parseFile is the equivalent of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +000089xmlParseFile (most of the bindings are automatically generated, and the xml
90prefix is removed and the casing convention are kept). All node seen at the
Daniel Veillard1177ca42003-04-26 22:29:54 +000091binding level share the same subset of accessors:</p><ul><li><code>name</code> : returns the node name</li>
92 <li><code>type</code> : returns a string indicating the node type</li>
93 <li><code>content</code> : returns the content of the node, it is based on
Daniel Veillardaf43f632002-03-08 15:05:20 +000094 xmlNodeGetContent() and hence is recursive.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +000095 <li><code>parent</code> , <code>children</code>, <code>last</code>,
Daniel Veillardaf43f632002-03-08 15:05:20 +000096 <code>next</code>, <code>prev</code>, <code>doc</code>,
97 <code>properties</code>: pointing to the associated element in the tree,
98 those may return None in case no such link exists.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +000099</ul><p>Also note the need to explicitly deallocate documents with freeDoc() .
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000100Reference counting for libxml2 trees would need quite a lot of work to
101function properly, and rather than risk memory leaks if not implemented
102correctly it sounds safer to have an explicit function to free a tree. The
103wrapper python objects like doc, root or child are them automatically garbage
Daniel Veillard1177ca42003-04-26 22:29:54 +0000104collected.</p><h3>validate.py:</h3><p>This test check the validation interfaces and redirection of error
105messages:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000106
Daniel Veillard63d83142002-05-20 06:51:05 +0000107#deactivate error messages from the validation
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000108def noerr(ctx, str):
109 pass
110
111libxml2.registerErrorHandler(noerr, None)
112
Daniel Veillard024f1992003-12-10 16:43:49 +0000113ctxt = libxml2.createFileParserCtxt("invalid.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000114ctxt.validate(1)
115ctxt.parseDocument()
116doc = ctxt.doc()
117valid = ctxt.isValid()
118doc.freeDoc()
119if valid != 0:
Daniel Veillard024f1992003-12-10 16:43:49 +0000120 print "validity check failed"</pre><p>The first thing to notice is the call to registerErrorHandler(), it
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000121defines a new error handler global to the library. It is used to avoid seeing
Daniel Veillard1177ca42003-04-26 22:29:54 +0000122the error messages when trying to validate the invalid document.</p><p>The main interest of that test is the creation of a parser context with
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000123createFileParserCtxt() and how the behaviour can be changed before calling
Daniel Veillard63d83142002-05-20 06:51:05 +0000124parseDocument() . Similarly the informations resulting from the parsing phase
Daniel Veillard1177ca42003-04-26 22:29:54 +0000125are also available using context methods.</p><p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000126C function interfaces in terms of objects method as much as possible. The
127best to get a complete view of what methods are supported is to look at the
Daniel Veillard1177ca42003-04-26 22:29:54 +0000128libxml2.py module containing all the wrappers.</p><h3>push.py:</h3><p>This test show how to activate the push parser interface:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000129
Daniel Veillard024f1992003-12-10 16:43:49 +0000130ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
131ctxt.parseChunk("/&gt;", 2, 1)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000132doc = ctxt.doc()
133
Daniel Veillard1177ca42003-04-26 22:29:54 +0000134doc.freeDoc()</pre><p>The context is created with a special call based on the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000135xmlCreatePushParser() from the C library. The first argument is an optional
Daniel Veillard63d83142002-05-20 06:51:05 +0000136SAX callback object, then the initial set of data, the length and the name of
Daniel Veillard1177ca42003-04-26 22:29:54 +0000137the resource in case URI-References need to be computed by the parser.</p><p>Then the data are pushed using the parseChunk() method, the last call
138setting the third argument terminate to 1.</p><h3>pushSAX.py:</h3><p>this test show the use of the event based parsing interfaces. In this case
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000139the parser does not build a document, but provides callback information as
Daniel Veillard1177ca42003-04-26 22:29:54 +0000140the parser makes progresses analyzing the data being provided:</p><pre>import libxml2
Daniel Veillard024f1992003-12-10 16:43:49 +0000141log = ""
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000142
143class callback:
144 def startDocument(self):
145 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000146 log = log + "startDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000147
148 def endDocument(self):
149 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000150 log = log + "endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000151
152 def startElement(self, tag, attrs):
153 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000154 log = log + "startElement %s %s:" % (tag, attrs)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000155
156 def endElement(self, tag):
157 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000158 log = log + "endElement %s:" % (tag)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000159
160 def characters(self, data):
161 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000162 log = log + "characters: %s:" % (data)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000163
164 def warning(self, msg):
165 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000166 log = log + "warning: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000167
168 def error(self, msg):
169 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000170 log = log + "error: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000171
172 def fatalError(self, msg):
173 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000174 log = log + "fatalError: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000175
176handler = callback()
177
Daniel Veillard024f1992003-12-10 16:43:49 +0000178ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
179chunk = " url='tst'&gt;b"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000180ctxt.parseChunk(chunk, len(chunk), 0)
Daniel Veillard024f1992003-12-10 16:43:49 +0000181chunk = "ar&lt;/foo&gt;"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000182ctxt.parseChunk(chunk, len(chunk), 1)
183
Daniel Veillard024f1992003-12-10 16:43:49 +0000184reference = "startDocument:startElement foo {'url': 'tst'}:" + \
185 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000186if log != reference:
Daniel Veillard024f1992003-12-10 16:43:49 +0000187 print "Error got: %s" % log
188 print "Expected: %s" % reference</pre><p>The key object in that test is the handler, it provides a number of entry
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000189points which can be called by the parser as it makes progresses to indicate
190the information set obtained. The full set of callback is larger than what
191the callback class in that specific example implements (see the SAX
192definition for a complete list). The wrapper will only call those supplied by
193the object when activated. The startElement receives the names of the element
Daniel Veillard1177ca42003-04-26 22:29:54 +0000194and a dictionary containing the attributes carried by this element.</p><p>Also note that the reference string generated from the callback shows a
Daniel Veillard024f1992003-12-10 16:43:49 +0000195single character call even though the string "bar" is passed to the parser
Daniel Veillard1177ca42003-04-26 22:29:54 +0000196from 2 different call to parseChunk()</p><h3>xpath.py:</h3><p>This is a basic test of XPath wrappers support</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000197
Daniel Veillard024f1992003-12-10 16:43:49 +0000198doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000199ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000200res = ctxt.xpathEval("//*")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000201if len(res) != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000202 print "xpath query: wrong node set size"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000203 sys.exit(1)
Daniel Veillard024f1992003-12-10 16:43:49 +0000204if res[0].name != "doc" or res[1].name != "foo":
205 print "xpath query: wrong node set value"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000206 sys.exit(1)
207doc.freeDoc()
Daniel Veillard1177ca42003-04-26 22:29:54 +0000208ctxt.xpathFreeContext()</pre><p>This test parses a file, then create an XPath context to evaluate XPath
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000209expression on it. The xpathEval() method execute an XPath query and returns
210the result mapped in a Python way. String and numbers are natively converted,
211and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
Daniel Veillard63d83142002-05-20 06:51:05 +0000212the document, the XPath context need to be freed explicitly, also not that
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000213the result of the XPath query may point back to the document tree and hence
Daniel Veillard1177ca42003-04-26 22:29:54 +0000214the document must be freed after the result of the query is used.</p><h3>xpathext.py:</h3><p>This test shows how to extend the XPath engine with functions written in
215python:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000216
217def foo(ctx, x):
218 return x + 1
219
Daniel Veillard024f1992003-12-10 16:43:49 +0000220doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000221ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000222libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
223res = ctxt.xpathEval("foo(1)")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000224if res != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000225 print "xpath extension failure"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000226doc.freeDoc()
Daniel Veillard1177ca42003-04-26 22:29:54 +0000227ctxt.xpathFreeContext()</pre><p>Note how the extension function is registered with the context (but that
228part is not yet finalized, this may change slightly in the future).</p><h3>tstxpath.py:</h3><p>This test is similar to the previous one but shows how the extension
229function can access the XPath evaluation context:</p><pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000230 global called
231
232 #
233 # test that access to the XPath evaluation contexts
234 #
235 pctxt = libxml2.xpathParserContext(_obj=ctx)
236 ctxt = pctxt.context()
237 called = ctxt.function()
Daniel Veillard1177ca42003-04-26 22:29:54 +0000238 return x + 1</pre><p>All the interfaces around the XPath parser(or rather evaluation) context
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000239are not finalized, but it should be sufficient to do contextual work at the
Daniel Veillard1177ca42003-04-26 22:29:54 +0000240evaluation point.</p><h3>Memory debugging:</h3><p>last but not least, all tests starts with the following prologue:</p><pre>#memory debug specific
241libxml2.debugMemory(1)</pre><p>and ends with the following epilogue:</p><pre>#memory debug specific
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000242libxml2.cleanupParser()
243if libxml2.debugMemory(1) == 0:
Daniel Veillard024f1992003-12-10 16:43:49 +0000244 print "OK"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000245else:
Daniel Veillard024f1992003-12-10 16:43:49 +0000246 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
Daniel Veillard1177ca42003-04-26 22:29:54 +0000247 libxml2.dumpMemory()</pre><p>Those activate the memory debugging interface of libxml2 where all
Daniel Veillard63d83142002-05-20 06:51:05 +0000248allocated block in the library are tracked. The prologue then cleans up the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000249library state and checks that all allocated memory has been freed. If not it
Daniel Veillard1177ca42003-04-26 22:29:54 +0000250calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p><p><a href="bugs.html">Daniel Veillard</a></p></td></tr></table></td></tr></table></td></tr></table></td></tr></table></td></tr></table></body></html>