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Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]1<?xml version="1.0" encoding="ISO-8859-1"?>
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Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]9A:link, A:visited, A:active { text-decoration: underline }
MST 2004 John Fleckb759b302004-12-21 15:14:08 +0000[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="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.zveno.com/open_source/libxml2xslt.html">MacOsX binaries</a></li><li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal 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 +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>
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]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 Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]14or libxslt wrappers or bindings:</p><ul><li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a> seems the
Daniel Veillardc14401e2002-11-20 14:28:17 +0000[diff] [blame]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>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]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>
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 Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]22 <li><a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]23 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]24 libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]25 application server</a>.</li>
Daniel Veillard4ac494b2003-09-18 15:08:00 +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>
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]28 <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides an
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]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>
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]36 <li>Wai-Sun "Squidster" 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]37 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 +0000[diff] [blame]39 <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
40 Tcl</a>.</li>
41 <li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]42 <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a> is
Daniel Veillard806cada2003-03-19 21:58:59 +0000[diff] [blame]43 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 +0000[diff] [blame]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>
Daniel Veillardb78757b2004-12-30 21:30:23 +0000[diff] [blame^]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.)
52</li></ul><p>The distribution includes a set of Python bindings, which are guaranteed
Daniel Veillardc0801af2002-05-28 16:28:42 +0000[diff] [blame]53to be maintained as part of the library in the future, though the Python
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]54interface 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 +0000[diff] [blame]55maintains <a href="http://users.skynet.be/sbi/libxml-python/">a Windows port
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]56of 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 +0000[diff] [blame]57<a href="libxml2-api.xml">an XML API description file</a> which allows to
58automate a large part of the Python bindings, this includes function
Daniel Veillard7b4b2f92003-01-06 13:11:20 +0000[diff] [blame]59descriptions, enums, structures, typedefs, etc... The Python script used to
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]60build 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 +0000[diff] [blame]61 RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
62 RPM</a>).</li>
Daniel Veillard0b28e882002-07-24 23:47:05 +0000[diff] [blame]63 <li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]64 module distribution</a> corresponding to your installed version of
65 libxml2 and libxslt. Note that to install it you will need both libxml2
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]66 and libxslt installed and run "python setup.py build install" in the
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]67 module tree.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]68</ul><p>The distribution includes a set of examples and regression tests for the
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]69python bindings in the <code>python/tests</code> directory. Here are some
MST 2003 John Fleck2dffb762003-11-29 04:41:24 +0000[diff] [blame]70excerpts 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]71
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]72doc = libxml2.parseFile("tst.xml")
73if doc.name != "tst.xml":
74 print "doc.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]75 sys.exit(1)
76root = doc.children
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]77if root.name != "doc":
78 print "root.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]79 sys.exit(1)
80child = root.children
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]81if child.name != "foo":
82 print "child.name failed"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]83 sys.exit(1)
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]84doc.freeDoc()</pre><p>The Python module is called libxml2; parseFile is the equivalent of
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]85xmlParseFile (most of the bindings are automatically generated, and the xml
86prefix is removed and the casing convention are kept). All node seen at the
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]87binding level share the same subset of accessors:</p><ul><li><code>name</code> : returns the node name</li>
88 <li><code>type</code> : returns a string indicating the node type</li>
89 <li><code>content</code> : returns the content of the node, it is based on
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]90 xmlNodeGetContent() and hence is recursive.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]91 <li><code>parent</code> , <code>children</code>, <code>last</code>,
Daniel Veillardaf43f632002-03-08 15:05:20 +0000[diff] [blame]92 <code>next</code>, <code>prev</code>, <code>doc</code>,
93 <code>properties</code>: pointing to the associated element in the tree,
94 those may return None in case no such link exists.</li>
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]95</ul><p>Also note the need to explicitly deallocate documents with freeDoc() .
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]96Reference counting for libxml2 trees would need quite a lot of work to
97function properly, and rather than risk memory leaks if not implemented
98correctly it sounds safer to have an explicit function to free a tree. The
99wrapper python objects like doc, root or child are them automatically garbage
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]100collected.</p><h3>validate.py:</h3><p>This test check the validation interfaces and redirection of error
101messages:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]102
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]103#deactivate error messages from the validation
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]104def noerr(ctx, str):
105 pass
106
107libxml2.registerErrorHandler(noerr, None)
108
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]109ctxt = libxml2.createFileParserCtxt("invalid.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]110ctxt.validate(1)
111ctxt.parseDocument()
112doc = ctxt.doc()
113valid = ctxt.isValid()
114doc.freeDoc()
115if valid != 0:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]116 print "validity check failed"</pre><p>The first thing to notice is the call to registerErrorHandler(), it
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]117defines a new error handler global to the library. It is used to avoid seeing
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]118the 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 +0000[diff] [blame]119createFileParserCtxt() and how the behaviour can be changed before calling
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]120parseDocument() . Similarly the informations resulting from the parsing phase
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]121are 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 +0000[diff] [blame]122C function interfaces in terms of objects method as much as possible. The
123best to get a complete view of what methods are supported is to look at the
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]124libxml2.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]125
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]126ctxt = libxml2.createPushParser(None, "&lt;foo", 4, "test.xml")
127ctxt.parseChunk("/&gt;", 2, 1)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]128doc = ctxt.doc()
129
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]130doc.freeDoc()</pre><p>The context is created with a special call based on the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]131xmlCreatePushParser() from the C library. The first argument is an optional
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]132SAX callback object, then the initial set of data, the length and the name of
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]133the 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
134setting 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 +0000[diff] [blame]135the parser does not build a document, but provides callback information as
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]136the parser makes progresses analyzing the data being provided:</p><pre>import libxml2
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]137log = ""
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]138
139class callback:
140 def startDocument(self):
141 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]142 log = log + "startDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]143
144 def endDocument(self):
145 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]146 log = log + "endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]147
148 def startElement(self, tag, attrs):
149 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]150 log = log + "startElement %s %s:" % (tag, attrs)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]151
152 def endElement(self, tag):
153 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]154 log = log + "endElement %s:" % (tag)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]155
156 def characters(self, data):
157 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]158 log = log + "characters: %s:" % (data)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]159
160 def warning(self, msg):
161 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]162 log = log + "warning: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]163
164 def error(self, msg):
165 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]166 log = log + "error: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]167
168 def fatalError(self, msg):
169 global log
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]170 log = log + "fatalError: %s:" % (msg)
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]171
172handler = callback()
173
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]174ctxt = libxml2.createPushParser(handler, "&lt;foo", 4, "test.xml")
175chunk = " url='tst'&gt;b"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]176ctxt.parseChunk(chunk, len(chunk), 0)
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]177chunk = "ar&lt;/foo&gt;"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]178ctxt.parseChunk(chunk, len(chunk), 1)
179
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]180reference = "startDocument:startElement foo {'url': 'tst'}:" + \
181 "characters: bar:endElement foo:endDocument:"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]182if log != reference:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]183 print "Error got: %s" % log
184 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 +0000[diff] [blame]185points which can be called by the parser as it makes progresses to indicate
186the information set obtained. The full set of callback is larger than what
187the callback class in that specific example implements (see the SAX
188definition for a complete list). The wrapper will only call those supplied by
189the object when activated. The startElement receives the names of the element
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]190and 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 +0000[diff] [blame]191single character call even though the string "bar" is passed to the parser
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]192from 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]193
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]194doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]195ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]196res = ctxt.xpathEval("//*")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]197if len(res) != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]198 print "xpath query: wrong node set size"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]199 sys.exit(1)
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]200if res[0].name != "doc" or res[1].name != "foo":
201 print "xpath query: wrong node set value"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]202 sys.exit(1)
203doc.freeDoc()
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]204ctxt.xpathFreeContext()</pre><p>This test parses a file, then create an XPath context to evaluate XPath
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]205expression on it. The xpathEval() method execute an XPath query and returns
206the result mapped in a Python way. String and numbers are natively converted,
207and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]208the document, the XPath context need to be freed explicitly, also not that
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]209the result of the XPath query may point back to the document tree and hence
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]210the 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
211python:</p><pre>import libxml2
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]212
213def foo(ctx, x):
214 return x + 1
215
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]216doc = libxml2.parseFile("tst.xml")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]217ctxt = doc.xpathNewContext()
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]218libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
219res = ctxt.xpathEval("foo(1)")
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]220if res != 2:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]221 print "xpath extension failure"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]222doc.freeDoc()
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]223ctxt.xpathFreeContext()</pre><p>Note how the extension function is registered with the context (but that
224part 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
225function can access the XPath evaluation context:</p><pre>def foo(ctx, x):
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]226 global called
227
228 #
229 # test that access to the XPath evaluation contexts
230 #
231 pctxt = libxml2.xpathParserContext(_obj=ctx)
232 ctxt = pctxt.context()
233 called = ctxt.function()
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]234 return x + 1</pre><p>All the interfaces around the XPath parser(or rather evaluation) context
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]235are not finalized, but it should be sufficient to do contextual work at the
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]236evaluation point.</p><h3>Memory debugging:</h3><p>last but not least, all tests starts with the following prologue:</p><pre>#memory debug specific
237libxml2.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]238libxml2.cleanupParser()
239if libxml2.debugMemory(1) == 0:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]240 print "OK"
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]241else:
Daniel Veillard024f1992003-12-10 16:43:49 +0000[diff] [blame]242 print "Memory leak %d bytes" % (libxml2.debugMemory(1))
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]243 libxml2.dumpMemory()</pre><p>Those activate the memory debugging interface of libxml2 where all
Daniel Veillard63d83142002-05-20 06:51:05 +0000[diff] [blame]244allocated block in the library are tracked. The prologue then cleans up the
Daniel Veillard6dbcaf82002-02-20 14:37:47 +0000[diff] [blame]245library state and checks that all allocated memory has been freed. If not it
Daniel Veillard1177ca42003-04-26 22:29:54 +0000[diff] [blame]246calls 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>