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Daniel Veillardd2190fa2010-09-30 13:58:22 +0200[diff] [blame]1<?xml version="1.0" encoding="UTF-8"?>
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
Daniel Veillardd2190fa2010-09-30 13:58:22 +0200[diff] [blame]3<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css">
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Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]9A:link, A:visited, A:active { text-decoration: underline }
Daniel Veillard28fdf8b2011-03-07 08:12:39 +0800[diff] [blame]10</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://opencsw.org/packages/libxml2">Solaris binaries</a></li><li><a href="http://www.explain.com.au/oss/libxml2xslt.html">MacOsX binaries</a></li><li><a href="http://lxml.de/">lxml Python bindings</a></li><li><a href="http://cpan.uwinnipeg.ca/dist/XML-LibXML">Perl bindings</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://libxml.rubyforge.org/">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 Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]11libxml2, the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
12(<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 Veillarde38217a2013-05-10 15:40:13 +0800[diff] [blame^]14or libxslt wrappers or bindings:</p><ul>
15 <li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]16 most up-to-date C++ bindings for libxml2, check the <a href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a>
17 and the <a href="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libxmlplusplus/libxml%2b%2b/examples/">examples</a>.</li>
18 <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
19 based on the gdome2 bindings</a> maintained by Tobias Peters.</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]20 <li>and a third C++ wrapper by Peter Jones &lt;pjones@pmade.org&gt;
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]21 <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 +0000[diff] [blame]22 </li>
Daniel Veillardd012f482007-08-22 17:36:57 +0000[diff] [blame]23 <li>XML::LibXML <a href="http://cpan.uwinnipeg.ca/dist/XML-LibXML">Perl
24 bindings</a> are available on CPAN, as well as XML::LibXSLT
25 <a href="http://cpan.uwinnipeg.ca/dist/XML-LibXSLT">Perl libxslt
26 bindings</a>.</li>
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]27 <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
28 Libxml2 Perl bindings.</li>
29 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an
30 earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li>
31 <li>Gopal.V and Peter Minten develop <a href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set of
32 C# libxml2 bindings.</li>
33 <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
34 libxml2</a> with Kylix, Delphi and other Pascal compilers.</li>
35 <li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2
36 implementation for Kylix2/D5/D6 from Borland.</li>
37 <li>There is <a href="http://libxml.rubyforge.org/">bindings for Ruby</a>
38 and libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
39 maintained by Tobias Peters.</li>
40 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
41 Tcl</a>.</li>
William M. Brack43a87292007-02-15 20:41:02 +0000[diff] [blame]42 <li>libxml2 and libxslt are the default XML libraries for PHP5.</li>
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]43 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is
44 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and
45 libxslt as part of GNU ClasspathX project.</li>
46 <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt, look for
47 <a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.</li>
48 <li><a href="http://www.satimage.fr/software/en/xml_suite.html">Satimage</a>
49 provides <a href="http://www.satimage.fr/software/en/downloads_osaxen.html">XMLLib
50 osax</a>. This is an osax for Mac OS X with a set of commands to
51 implement in AppleScript the XML DOM, XPATH and XSLT. Also includes
52 commands for Property-lists (Apple's fast lookup table XML format.)</li>
53 <li>Francesco Montorsi developped <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
57to be maintained as part of the library in the future, though the Python
58interface have not yet reached the completeness of the C API.</p><p>Note that some of the Python purist dislike the default set of Python
Daniel Veillard28fdf8b2011-03-07 08:12:39 +0800[diff] [blame]59bindings, rather than complaining I suggest they have a look at <a href="http://lxml.de/">lxml the more pythonic bindings for libxml2
60and libxslt</a> and <a href="http://lxml.de/mailinglist/">check the mailing-list</a>.</p><p><a href="mailto:stephane.bidoul@softwareag.com">Stéphane Bidoul</a>
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]61maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
62of the Python bindings</a>.</p><p>Note to people interested in building bindings, the API is formalized as
63<a href="libxml2-api.xml">an XML API description file</a> which allows to
64automate a large part of the Python bindings, this includes function
65descriptions, enums, structures, typedefs, etc... The Python script used to
Daniel Veillarde38217a2013-05-10 15:40:13 +0800[diff] [blame^]66build the bindings is python/generator.py in the source distribution.</p><p>To install the Python bindings there are 2 options:</p><ul>
67 <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 Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]68 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
69 RPM</a>).</li>
70 <li>Otherwise use the <a href="ftp://xmlsoft.org/libxml2/python/">libxml2-python
71 module distribution</a> corresponding to your installed version of
72 libxml2 and libxslt. Note that to install it you will need both libxml2
73 and libxslt installed and run "python setup.py build install" in the
74 module tree.</li>
75</ul><p>The distribution includes a set of examples and regression tests for the
76python bindings in the <code>python/tests</code> directory. Here are some
77excerpts 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 +0000[diff] [blame]78
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]79doc = libxml2.parseFile("tst.xml")
80if doc.name != "tst.xml":
81 print "doc.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]82 sys.exit(1)
83root = doc.children
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]84if root.name != "doc":
85 print "root.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]86 sys.exit(1)
87child = root.children
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]88if child.name != "foo":
89 print "child.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]90 sys.exit(1)
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]91doc.freeDoc()</pre><p>The Python module is called libxml2; parseFile is the equivalent of
92xmlParseFile (most of the bindings are automatically generated, and the xml
93prefix is removed and the casing convention are kept). All node seen at the
Daniel Veillarde38217a2013-05-10 15:40:13 +0800[diff] [blame^]94binding level share the same subset of accessors:</p><ul>
95 <li><code>name</code> : returns the node name</li>
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]96 <li><code>type</code> : returns a string indicating the node type</li>
97 <li><code>content</code> : returns the content of the node, it is based on
98 xmlNodeGetContent() and hence is recursive.</li>
99 <li><code>parent</code> , <code>children</code>, <code>last</code>,
100 <code>next</code>, <code>prev</code>, <code>doc</code>,
101 <code>properties</code>: pointing to the associated element in the tree,
102 those may return None in case no such link exists.</li>
103</ul><p>Also note the need to explicitly deallocate documents with freeDoc() .
104Reference counting for libxml2 trees would need quite a lot of work to
105function properly, and rather than risk memory leaks if not implemented
106correctly it sounds safer to have an explicit function to free a tree. The
107wrapper python objects like doc, root or child are them automatically garbage
108collected.</p><h3>validate.py:</h3><p>This test check the validation interfaces and redirection of error
109messages:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]110
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]111#deactivate error messages from the validation
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]112def noerr(ctx, str):
113 pass
114
115libxml2.registerErrorHandler(noerr, None)
116
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]117ctxt = libxml2.createFileParserCtxt("invalid.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]118ctxt.validate(1)
119ctxt.parseDocument()
120doc = ctxt.doc()
121valid = ctxt.isValid()
122doc.freeDoc()
123if valid != 0:
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]124 print "validity check failed"</pre><p>The first thing to notice is the call to registerErrorHandler(), it
125defines a new error handler global to the library. It is used to avoid seeing
126the 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
127createFileParserCtxt() and how the behaviour can be changed before calling
William M. Brack43a87292007-02-15 20:41:02 +0000[diff] [blame]128parseDocument() . Similarly the information resulting from the parsing phase
129is also available using context methods.</p><p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]130C function interfaces in terms of objects method as much as possible. The
131best to get a complete view of what methods are supported is to look at the
132libxml2.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 +0000[diff] [blame]133
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]134ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
135ctxt.parseChunk("/&gt;", 2, 1)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]136doc = ctxt.doc()
137
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]138doc.freeDoc()</pre><p>The context is created with a special call based on the
139xmlCreatePushParser() from the C library. The first argument is an optional
140SAX callback object, then the initial set of data, the length and the name of
141the 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
142setting 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
143the parser does not build a document, but provides callback information as
144the parser makes progresses analyzing the data being provided:</p><pre>import libxml2
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]145log = ""
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]146
147class callback:
148 def startDocument(self):
149 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]150 log = log + "startDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]151
152 def endDocument(self):
153 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]154 log = log + "endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]155
156 def startElement(self, tag, attrs):
157 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]158 log = log + "startElement %s %s:" % (tag, attrs)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]159
160 def endElement(self, tag):
161 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]162 log = log + "endElement %s:" % (tag)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]163
164 def characters(self, data):
165 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]166 log = log + "characters: %s:" % (data)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]167
168 def warning(self, msg):
169 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]170 log = log + "warning: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]171
172 def error(self, msg):
173 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]174 log = log + "error: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]175
176 def fatalError(self, msg):
177 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]178 log = log + "fatalError: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]179
180handler = callback()
181
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]182ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
183chunk = " url='tst'&gt;b"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]184ctxt.parseChunk(chunk, len(chunk), 0)
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]185chunk = "ar&lt;/foo&gt;"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]186ctxt.parseChunk(chunk, len(chunk), 1)
187
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]188reference = "startDocument:startElement foo {'url': 'tst'}:" + \
189 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]190if log != reference:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]191 print "Error got: %s" % log
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]192 print "Expected: %s" % reference</pre><p>The key object in that test is the handler, it provides a number of entry
193points which can be called by the parser as it makes progresses to indicate
194the information set obtained. The full set of callback is larger than what
195the callback class in that specific example implements (see the SAX
196definition for a complete list). The wrapper will only call those supplied by
197the object when activated. The startElement receives the names of the element
198and a dictionary containing the attributes carried by this element.</p><p>Also note that the reference string generated from the callback shows a
199single character call even though the string "bar" is passed to the parser
200from 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 +0000[diff] [blame]201
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]202doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]203ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]204res = ctxt.xpathEval("//*")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]205if len(res) != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]206 print "xpath query: wrong node set size"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]207 sys.exit(1)
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]208if res[0].name != "doc" or res[1].name != "foo":
209 print "xpath query: wrong node set value"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]210 sys.exit(1)
211doc.freeDoc()
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]212ctxt.xpathFreeContext()</pre><p>This test parses a file, then create an XPath context to evaluate XPath
213expression on it. The xpathEval() method execute an XPath query and returns
214the result mapped in a Python way. String and numbers are natively converted,
215and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
216the document, the XPath context need to be freed explicitly, also not that
217the result of the XPath query may point back to the document tree and hence
218the 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
219python:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]220
221def foo(ctx, x):
222 return x + 1
223
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]224doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]225ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]226libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
227res = ctxt.xpathEval("foo(1)")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]228if res != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]229 print "xpath extension failure"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]230doc.freeDoc()
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]231ctxt.xpathFreeContext()</pre><p>Note how the extension function is registered with the context (but that
232part 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
233function can access the XPath evaluation context:</p><pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]234 global called
235
236 #
237 # test that access to the XPath evaluation contexts
238 #
239 pctxt = libxml2.xpathParserContext(_obj=ctx)
240 ctxt = pctxt.context()
241 called = ctxt.function()
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]242 return x + 1</pre><p>All the interfaces around the XPath parser(or rather evaluation) context
243are not finalized, but it should be sufficient to do contextual work at the
244evaluation point.</p><h3>Memory debugging:</h3><p>last but not least, all tests starts with the following prologue:</p><pre>#memory debug specific
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]245libxml2.debugMemory(1)</pre><p>and ends with the following epilogue:</p><pre>#memory debug specific
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]246libxml2.cleanupParser()
247if libxml2.debugMemory(1) == 0:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]248 print "OK"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]249else:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]250 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]251 libxml2.dumpMemory()</pre><p>Those activate the memory debugging interface of libxml2 where all
252allocated block in the library are tracked. The prologue then cleans up the
253library state and checks that all allocated memory has been freed. If not it
254calls 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>