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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">
Daniel Veillard373a4752002-02-21 14:46:29 +0000[diff] [blame]4TD {font-family: Verdana,Arial,Helvetica}
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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
14or libxslt wrappers or bindings:</p><ul><li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the
15 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>
17 <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>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]19 <li>and a third C++ wrapper by Peter Jones &lt;pjones@pmade.org&gt;
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]20 <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]21 </li>
Daniel Veillardd012f482007-08-22 17:36:57 +0000[diff] [blame]22 <li>XML::LibXML <a href="http://cpan.uwinnipeg.ca/dist/XML-LibXML">Perl
23 bindings</a> are available on CPAN, as well as XML::LibXSLT
24 <a href="http://cpan.uwinnipeg.ca/dist/XML-LibXSLT">Perl libxslt
25 bindings</a>.</li>
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]26 <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>
28 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an
29 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>
36 <li>There is <a href="http://libxml.rubyforge.org/">bindings for Ruby</a>
37 and 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>
39 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
40 Tcl</a>.</li>
William M. Brack43a87292007-02-15 20:41:02 +0000[diff] [blame]41 <li>libxml2 and libxslt are the default XML libraries for PHP5.</li>
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]42 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is
43 an effort to create a 100% JAXP-compatible Java wrapper for libxml2 and
44 libxslt as part of GNU ClasspathX project.</li>
45 <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>
47 <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
51 commands for Property-lists (Apple's fast lookup table XML format.)</li>
52 <li>Francesco Montorsi developped <a href="https://sourceforge.net/project/showfiles.php?group_id=51305&amp;package_id=45182">wxXml2</a>
53 wrappers that interface libxml2, allowing wxWidgets applications to
54 load/save/edit XML instances.</li>
55</ul><p>The distribution includes a set of Python bindings, which are guaranteed
56to be maintained as part of the library in the future, though the Python
57interface 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]58bindings, rather than complaining I suggest they have a look at <a href="http://lxml.de/">lxml the more pythonic bindings for libxml2
59and 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]60maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
61of the Python bindings</a>.</p><p>Note to people interested in building bindings, the API is formalized as
62<a href="libxml2-api.xml">an XML API description file</a> which allows to
63automate a large part of the Python bindings, this includes function
64descriptions, enums, structures, typedefs, etc... The Python script used to
65build 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
66 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
67 RPM</a>).</li>
68 <li>Otherwise use the <a href="ftp://xmlsoft.org/libxml2/python/">libxml2-python
69 module distribution</a> corresponding to your installed version of
70 libxml2 and libxslt. Note that to install it you will need both libxml2
71 and libxslt installed and run "python setup.py build install" in the
72 module tree.</li>
73</ul><p>The distribution includes a set of examples and regression tests for the
74python bindings in the <code>python/tests</code> directory. Here are some
75excerpts 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]76
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]77doc = libxml2.parseFile("tst.xml")
78if doc.name != "tst.xml":
79 print "doc.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]80 sys.exit(1)
81root = doc.children
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]82if root.name != "doc":
83 print "root.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]84 sys.exit(1)
85child = root.children
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]86if child.name != "foo":
87 print "child.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]88 sys.exit(1)
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]89doc.freeDoc()</pre><p>The Python module is called libxml2; parseFile is the equivalent of
90xmlParseFile (most of the bindings are automatically generated, and the xml
91prefix is removed and the casing convention are kept). All node seen at the
92binding level share the same subset of accessors:</p><ul><li><code>name</code> : returns the node name</li>
93 <li><code>type</code> : returns a string indicating the node type</li>
94 <li><code>content</code> : returns the content of the node, it is based on
95 xmlNodeGetContent() and hence is recursive.</li>
96 <li><code>parent</code> , <code>children</code>, <code>last</code>,
97 <code>next</code>, <code>prev</code>, <code>doc</code>,
98 <code>properties</code>: pointing to the associated element in the tree,
99 those may return None in case no such link exists.</li>
100</ul><p>Also note the need to explicitly deallocate documents with freeDoc() .
101Reference counting for libxml2 trees would need quite a lot of work to
102function properly, and rather than risk memory leaks if not implemented
103correctly it sounds safer to have an explicit function to free a tree. The
104wrapper python objects like doc, root or child are them automatically garbage
105collected.</p><h3>validate.py:</h3><p>This test check the validation interfaces and redirection of error
106messages:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]107
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]108#deactivate error messages from the validation
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]109def noerr(ctx, str):
110 pass
111
112libxml2.registerErrorHandler(noerr, None)
113
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]114ctxt = libxml2.createFileParserCtxt("invalid.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]115ctxt.validate(1)
116ctxt.parseDocument()
117doc = ctxt.doc()
118valid = ctxt.isValid()
119doc.freeDoc()
120if valid != 0:
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]121 print "validity check failed"</pre><p>The first thing to notice is the call to registerErrorHandler(), it
122defines a new error handler global to the library. It is used to avoid seeing
123the 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
124createFileParserCtxt() and how the behaviour can be changed before calling
William M. Brack43a87292007-02-15 20:41:02 +0000[diff] [blame]125parseDocument() . Similarly the information resulting from the parsing phase
126is 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]127C function interfaces in terms of objects method as much as possible. The
128best to get a complete view of what methods are supported is to look at the
129libxml2.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]130
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]131ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
132ctxt.parseChunk("/&gt;", 2, 1)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]133doc = ctxt.doc()
134
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]135doc.freeDoc()</pre><p>The context is created with a special call based on the
136xmlCreatePushParser() from the C library. The first argument is an optional
137SAX callback object, then the initial set of data, the length and the name of
138the 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
139setting 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
140the parser does not build a document, but provides callback information as
141the parser makes progresses analyzing the data being provided:</p><pre>import libxml2
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]142log = ""
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]143
144class callback:
145 def startDocument(self):
146 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]147 log = log + "startDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]148
149 def endDocument(self):
150 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]151 log = log + "endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]152
153 def startElement(self, tag, attrs):
154 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]155 log = log + "startElement %s %s:" % (tag, attrs)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]156
157 def endElement(self, tag):
158 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]159 log = log + "endElement %s:" % (tag)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]160
161 def characters(self, data):
162 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]163 log = log + "characters: %s:" % (data)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]164
165 def warning(self, msg):
166 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]167 log = log + "warning: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]168
169 def error(self, msg):
170 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]171 log = log + "error: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]172
173 def fatalError(self, msg):
174 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]175 log = log + "fatalError: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]176
177handler = callback()
178
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]179ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
180chunk = " url='tst'&gt;b"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]181ctxt.parseChunk(chunk, len(chunk), 0)
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]182chunk = "ar&lt;/foo&gt;"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]183ctxt.parseChunk(chunk, len(chunk), 1)
184
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]185reference = "startDocument:startElement foo {'url': 'tst'}:" + \
186 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]187if log != reference:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]188 print "Error got: %s" % log
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]189 print "Expected: %s" % reference</pre><p>The key object in that test is the handler, it provides a number of entry
190points which can be called by the parser as it makes progresses to indicate
191the information set obtained. The full set of callback is larger than what
192the callback class in that specific example implements (see the SAX
193definition for a complete list). The wrapper will only call those supplied by
194the object when activated. The startElement receives the names of the element
195and a dictionary containing the attributes carried by this element.</p><p>Also note that the reference string generated from the callback shows a
196single character call even though the string "bar" is passed to the parser
197from 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]198
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]199doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]200ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]201res = ctxt.xpathEval("//*")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]202if len(res) != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]203 print "xpath query: wrong node set size"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]204 sys.exit(1)
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]205if res[0].name != "doc" or res[1].name != "foo":
206 print "xpath query: wrong node set value"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]207 sys.exit(1)
208doc.freeDoc()
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]209ctxt.xpathFreeContext()</pre><p>This test parses a file, then create an XPath context to evaluate XPath
210expression on it. The xpathEval() method execute an XPath query and returns
211the result mapped in a Python way. String and numbers are natively converted,
212and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
213the document, the XPath context need to be freed explicitly, also not that
214the result of the XPath query may point back to the document tree and hence
215the 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
216python:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]217
218def foo(ctx, x):
219 return x + 1
220
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]221doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]222ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]223libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
224res = ctxt.xpathEval("foo(1)")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]225if res != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]226 print "xpath extension failure"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]227doc.freeDoc()
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]228ctxt.xpathFreeContext()</pre><p>Note how the extension function is registered with the context (but that
229part 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
230function can access the XPath evaluation context:</p><pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]231 global called
232
233 #
234 # test that access to the XPath evaluation contexts
235 #
236 pctxt = libxml2.xpathParserContext(_obj=ctx)
237 ctxt = pctxt.context()
238 called = ctxt.function()
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]239 return x + 1</pre><p>All the interfaces around the XPath parser(or rather evaluation) context
240are not finalized, but it should be sufficient to do contextual work at the
241evaluation 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]242libxml2.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]243libxml2.cleanupParser()
244if libxml2.debugMemory(1) == 0:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]245 print "OK"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]246else:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]247 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
Daniel Veillardf781dba2006-06-09 13:34:49 +0000[diff] [blame]248 libxml2.dumpMemory()</pre><p>Those activate the memory debugging interface of libxml2 where all
249allocated block in the library are tracked. The prologue then cleans up the
250library state and checks that all allocated memory has been freed. If not it
251calls 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>