Blame - doc/python.html - platform/external/libxml2

blob: 0c76415c5737d565c8e2a40140cc5af575f2aed9 [file] [log] [blame]

Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	1	<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/1999/REC-html401-19991224/loose.dtd">
				2	<html>
				3	<head>
				4	<meta content="text/html; charset=ISO-8859-1" http-equiv="Content-Type">
Daniel Veillard	c332dab	2002-03-29 14:08:27 +0000	[diff] [blame]	5	<link rel="SHORTCUT ICON" href="/favicon.ico">
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	6	<style type="text/css"><!--
Daniel Veillard	373a475	2002-02-21 14:46:29 +0000	[diff] [blame]	7	TD {font-family: Verdana,Arial,Helvetica}
				8	BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em}
				9	H1 {font-family: Verdana,Arial,Helvetica}
				10	H2 {font-family: Verdana,Arial,Helvetica}
				11	H3 {font-family: Verdana,Arial,Helvetica}
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	12	A:link, A:visited, A:active { text-decoration: underline }
				13	--></style>
				14	<title>Python and bindings</title>
				15	</head>
				16	<body bgcolor="#8b7765" text="#000000" link="#000000" vlink="#000000">
				17	<table border="0" width="100%" cellpadding="5" cellspacing="0" align="center"><tr>
				18	<td width="180">
				19	<a href="http://www.gnome.org/"><img src="smallfootonly.gif" alt="Gnome 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>
				20	</td>
				21	<td><table border="0" width="90%" cellpadding="2" cellspacing="0" align="center" bgcolor="#000000"><tr><td><table width="100%" border="0" cellspacing="1" cellpadding="3" bgcolor="#fffacd"><tr><td align="center">
				22	<h1>The XML C library for Gnome</h1>
				23	<h2>Python and bindings</h2>
				24	</td></tr></table></td></tr></table></td>
				25	</tr></table>
				26	<table border="0" cellpadding="4" cellspacing="0" width="100%" align="center"><tr><td bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="2" width="100%"><tr>
				27	<td valign="top" width="200" bgcolor="#8b7765"><table border="0" cellspacing="0" cellpadding="1" width="100%" bgcolor="#000000"><tr><td>
				28	<table width="100%" border="0" cellspacing="1" cellpadding="3">
				29	<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Main Menu</b></center></td></tr>
				30	<tr><td bgcolor="#fffacd"><ul>
				31	<li><a href="index.html">Home</a></li>
				32	<li><a href="intro.html">Introduction</a></li>
				33	<li><a href="FAQ.html">FAQ</a></li>
				34	<li><a href="docs.html">Documentation</a></li>
				35	<li><a href="bugs.html">Reporting bugs and getting help</a></li>
				36	<li><a href="help.html">How to help</a></li>
				37	<li><a href="downloads.html">Downloads</a></li>
				38	<li><a href="news.html">News</a></li>
				39	<li><a href="XMLinfo.html">XML</a></li>
				40	<li><a href="XSLT.html">XSLT</a></li>
				41	<li><a href="python.html">Python and bindings</a></li>
				42	<li><a href="architecture.html">libxml architecture</a></li>
				43	<li><a href="tree.html">The tree output</a></li>
				44	<li><a href="interface.html">The SAX interface</a></li>
				45	<li><a href="xmldtd.html">Validation & DTDs</a></li>
				46	<li><a href="xmlmem.html">Memory Management</a></li>
				47	<li><a href="encoding.html">Encodings support</a></li>
				48	<li><a href="xmlio.html">I/O Interfaces</a></li>
				49	<li><a href="catalog.html">Catalog support</a></li>
				50	<li><a href="library.html">The parser interfaces</a></li>
				51	<li><a href="entities.html">Entities or no entities</a></li>
				52	<li><a href="namespaces.html">Namespaces</a></li>
				53	<li><a href="upgrade.html">Upgrading 1.x code</a></li>
				54	<li><a href="threads.html">Thread safety</a></li>
				55	<li><a href="DOM.html">DOM Principles</a></li>
				56	<li><a href="example.html">A real example</a></li>
				57	<li><a href="contribs.html">Contributions</a></li>
				58	<li>
				59	<a href="xml.html">flat page</a>, <a href="site.xsl">stylesheet</a>
				60	</li>
				61	</ul></td></tr>
				62	</table>
				63	<table width="100%" border="0" cellspacing="1" cellpadding="3">
				64	<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>API Indexes</b></center></td></tr>
				65	<tr><td bgcolor="#fffacd"><ul>
				66	<li><a href="APIchunk0.html">Alphabetic</a></li>
				67	<li><a href="APIconstructors.html">Constructors</a></li>
				68	<li><a href="APIfunctions.html">Functions/Types</a></li>
				69	<li><a href="APIfiles.html">Modules</a></li>
				70	<li><a href="APIsymbols.html">Symbols</a></li>
				71	</ul></td></tr>
				72	</table>
				73	<table width="100%" border="0" cellspacing="1" cellpadding="3">
				74	<tr><td colspan="1" bgcolor="#eecfa1" align="center"><center><b>Related links</b></center></td></tr>
				75	<tr><td bgcolor="#fffacd"><ul>
				76	<li><a href="http://mail.gnome.org/archives/xml/">Mail archive</a></li>
				77	<li><a href="http://xmlsoft.org/XSLT/">XSLT libxslt</a></li>
				78	<li><a href="http://phd.cs.unibo.it/gdome2/">DOM gdome2</a></li>
Daniel Veillard	2d347fa	2002-03-17 10:34:11 +0000	[diff] [blame]	79	<li><a href="http://www.aleksey.com/xmlsec/">XML-DSig xmlsec</a></li>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	80	<li><a href="ftp://xmlsoft.org/">FTP</a></li>
				81	<li><a href="http://www.fh-frankfurt.de/~igor/projects/libxml/">Windows binaries</a></li>
				82	<li><a href="http://garypennington.net/libxml2/">Solaris binaries</a></li>
Daniel Veillard	e6d8e20	2002-05-02 06:11:10 +0000	[diff] [blame^]	83	<li><a href="http://sourceforge.net/projects/libxml2-pas/">Pascal bindings</a></li>
Daniel Veillard	2d347fa	2002-03-17 10:34:11 +0000	[diff] [blame]	84	<li><a href="http://bugzilla.gnome.org/buglist.cgi?product=libxml&product=libxml2">Bug Tracker</a></li>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	85	</ul></td></tr>
				86	</table>
				87	</td></tr></table></td>
				88	<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">
				89	<p>There is a number of language bindings and wrappers available for libxml2,
				90	the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>
				91	(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) in
				92	order to get updates to this list or to discuss the specific topic of libxml2
				93	or libxslt wrappers or bindings:</p>
				94	<ul>
				95	<li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	96	<a href="mailto:ari@lusis.org">Ari Johnson</a> provides a C++ wrapper
				97	for libxml:<br>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	98	Website: <a href="http://lusis.org/~ari/xml++/">http://lusis.org/~ari/xml++/</a><br>
				99	Download: <a href="http://lusis.org/~ari/xml++/libxml++.tar.gz">http://lusis.org/~ari/xml++/libxml++.tar.gz</a>
				100	</li>
				101	<li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ wrapper
				102	based on the gdome2 </a>bindings maintained by Tobias Peters.</li>
				103	<li>
				104	<a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">Matt
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	105	Sergeant</a> developped <a href="http://axkit.org/download/">XML::LibXSLT</a>, a perl wrapper for
				106	libxml2/libxslt as part of the <a href="http://axkit.com/">AxKit XML
				107	application server</a>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	108	</li>
				109	<li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	110	<a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a> provides and
				111	earlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	112	</li>
				113	<li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to glue
				114	libxml2</a> with Kylix, Delphi and other Pascal compilers</li>
Daniel Veillard	b2fb8ed	2002-04-01 09:33:12 +0000	[diff] [blame]	115	<li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a DOM2
Daniel Veillard	a8a89fe	2002-04-12 21:03:34 +0000	[diff] [blame]	116	implementation for Kylix2/D5/D6 from Borland</li>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	117	<li>Wai-Sun "Squidster" Chia provides <a href="http://www.rubycolor.org/arc/redist/">bindings for Ruby</a> and
				118	libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a> module
				119	maintained by Tobias Peters.</li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	120	<li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings for
Daniel Veillard	b9e469a	2002-02-21 12:08:42 +0000	[diff] [blame]	121	Tcl</a>
				122	</li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	123	<li>There is support for libxml2 in the DOM module of PHP.</li>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	124	</ul>
				125	<p>The distribution includes a set of Python bindings, which are garanteed to
				126	be maintained as part of the library in the future, though the Python
Daniel Veillard	0b79dfe	2002-02-23 13:02:31 +0000	[diff] [blame]	127	interface have not yet reached the maturity of the C API.</p>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	128	<p>To install the Python bindings there are 2 options:</p>
Daniel Veillard	0b79dfe	2002-02-23 13:02:31 +0000	[diff] [blame]	129	<ul>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	130	<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
				131	RPM</a> (and if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-python
				132	RPM</a>).</li>
				133	<li>Otherwise use the <a href="ftp://xmlsoft.org/python/">libxml2-python
				134	module distribution</a> corresponding to your installed version of
				135	libxml2 and libxslt. Note that to install it you will need both libxml2
				136	and libxslt installed and run "python setup.py build install" in the
				137	module tree.</li>
Daniel Veillard	0b79dfe	2002-02-23 13:02:31 +0000	[diff] [blame]	138	</ul>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	139	<p>The distribution includes a set of examples and regression tests for the
				140	python bindings in the <code>python/tests</code> directory. Here are some
				141	excepts from those tests:</p>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	142	<h3>tst.py:</h3>
				143	<p>This is a basic test of the file interface and DOM navigation:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	144	<pre>import libxml2
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	145
				146	doc = libxml2.parseFile("tst.xml")
				147	if doc.name != "tst.xml":
				148	print "doc.name failed"
				149	sys.exit(1)
				150	root = doc.children
				151	if root.name != "doc":
				152	print "root.name failed"
				153	sys.exit(1)
				154	child = root.children
				155	if child.name != "foo":
				156	print "child.name failed"
				157	sys.exit(1)
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	158	doc.freeDoc()</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	159	<p>The Python module is called libxml2, parseFile is the equivalent of
				160	xmlParseFile (most of the bindings are automatically generated, and the xml
				161	prefix is removed and the casing convention are kept). All node seen at the
				162	binding level share the same subset of accesors:</p>
				163	<ul>
				164	<li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	165	<code>name</code> : returns the node name</li>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	166	<li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	167	<code>type</code> : returns a string indicating the node
				168	typ<code>e</code>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	169	</li>
				170	<li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	171	<code>content</code> : returns the content of the node, it is based on
				172	xmlNodeGetContent() and hence is recursive.</li>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	173	<li>
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	174	<code>parent</code> , <code>children</code>, <code>last</code>,
				175	<code>next</code>, <code>prev</code>, <code>doc</code>,
				176	<code>properties</code>: pointing to the associated element in the tree,
				177	those may return None in case no such link exists.</li>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	178	</ul>
				179	<p>Also note the need to explicitely deallocate documents with freeDoc() .
				180	Reference counting for libxml2 trees would need quite a lot of work to
				181	function properly, and rather than risk memory leaks if not implemented
				182	correctly it sounds safer to have an explicit function to free a tree. The
				183	wrapper python objects like doc, root or child are them automatically garbage
				184	collected.</p>
				185	<h3>validate.py:</h3>
				186	<p>This test check the validation interfaces and redirection of error
				187	messages:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	188	<pre>import libxml2
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	189
				190	#desactivate error messages from the validation
				191	def noerr(ctx, str):
				192	pass
				193
				194	libxml2.registerErrorHandler(noerr, None)
				195
				196	ctxt = libxml2.createFileParserCtxt("invalid.xml")
				197	ctxt.validate(1)
				198	ctxt.parseDocument()
				199	doc = ctxt.doc()
				200	valid = ctxt.isValid()
				201	doc.freeDoc()
				202	if valid != 0:
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	203	print "validity chec failed"</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	204	<p>The first thing to notice is the call to registerErrorHandler(), it
				205	defines a new error handler global to the library. It is used to avoid seeing
				206	the error messages when trying to validate the invalid document.</p>
				207	<p>The main interest of that test is the creation of a parser context with
				208	createFileParserCtxt() and how the behaviour can be changed before calling
				209	parseDocument() . Similary the informations resulting from the parsing phase
				210	are also available using context methods.</p>
				211	<p>Contexts like nodes are defined as class and the libxml2 wrappers maps the
				212	C function interfaces in terms of objects method as much as possible. The
				213	best to get a complete view of what methods are supported is to look at the
				214	libxml2.py module containing all the wrappers.</p>
				215	<h3>push.py:</h3>
				216	<p>This test show how to activate the push parser interface:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	217	<pre>import libxml2
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	218
				219	ctxt = libxml2.createPushParser(None, "<foo", 4, "test.xml")
				220	ctxt.parseChunk("/>", 2, 1)
				221	doc = ctxt.doc()
				222
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	223	doc.freeDoc()</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	224	<p>The context is created with a speciall call based on the
				225	xmlCreatePushParser() from the C library. The first argument is an optional
				226	SAX callback object, then the initial set of data, the lenght and the name of
				227	the resource in case URI-References need to be computed by the parser.</p>
				228	<p>Then the data are pushed using the parseChunk() method, the last call
				229	setting the thrird argument terminate to 1.</p>
				230	<h3>pushSAX.py:</h3>
				231	<p>this test show the use of the event based parsing interfaces. In this case
				232	the parser does not build a document, but provides callback information as
				233	the parser makes progresses analyzing the data being provided:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	234	<pre>import libxml2
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	235	log = ""
				236
				237	class callback:
				238	def startDocument(self):
				239	global log
				240	log = log + "startDocument:"
				241
				242	def endDocument(self):
				243	global log
				244	log = log + "endDocument:"
				245
				246	def startElement(self, tag, attrs):
				247	global log
				248	log = log + "startElement %s %s:" % (tag, attrs)
				249
				250	def endElement(self, tag):
				251	global log
				252	log = log + "endElement %s:" % (tag)
				253
				254	def characters(self, data):
				255	global log
				256	log = log + "characters: %s:" % (data)
				257
				258	def warning(self, msg):
				259	global log
				260	log = log + "warning: %s:" % (msg)
				261
				262	def error(self, msg):
				263	global log
				264	log = log + "error: %s:" % (msg)
				265
				266	def fatalError(self, msg):
				267	global log
				268	log = log + "fatalError: %s:" % (msg)
				269
				270	handler = callback()
				271
				272	ctxt = libxml2.createPushParser(handler, "<foo", 4, "test.xml")
				273	chunk = " url='tst'>b"
				274	ctxt.parseChunk(chunk, len(chunk), 0)
				275	chunk = "ar</foo>"
				276	ctxt.parseChunk(chunk, len(chunk), 1)
				277
Daniel Veillard	fcbfa2d	2002-02-21 17:54:27 +0000	[diff] [blame]	278	reference = "startDocument:startElement foo {'url': 'tst'}:" + \
				279	"characters: bar:endElement foo:endDocument:"
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	280	if log != reference:
				281	print "Error got: %s" % log
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	282	print "Exprected: %s" % reference</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	283	<p>The key object in that test is the handler, it provides a number of entry
				284	points which can be called by the parser as it makes progresses to indicate
				285	the information set obtained. The full set of callback is larger than what
				286	the callback class in that specific example implements (see the SAX
				287	definition for a complete list). The wrapper will only call those supplied by
				288	the object when activated. The startElement receives the names of the element
				289	and a dictionnary containing the attributes carried by this element.</p>
				290	<p>Also note that the reference string generated from the callback shows a
				291	single character call even though the string "bar" is passed to the parser
				292	from 2 different call to parseChunk()</p>
				293	<h3>xpath.py:</h3>
				294	<p>This is a basic test of XPath warppers support</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	295	<pre>import libxml2
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	296
				297	doc = libxml2.parseFile("tst.xml")
				298	ctxt = doc.xpathNewContext()
				299	res = ctxt.xpathEval("//*")
				300	if len(res) != 2:
				301	print "xpath query: wrong node set size"
				302	sys.exit(1)
				303	if res[0].name != "doc" or res[1].name != "foo":
				304	print "xpath query: wrong node set value"
				305	sys.exit(1)
				306	doc.freeDoc()
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	307	ctxt.xpathFreeContext()</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	308	<p>This test parses a file, then create an XPath context to evaluate XPath
				309	expression on it. The xpathEval() method execute an XPath query and returns
				310	the result mapped in a Python way. String and numbers are natively converted,
				311	and node sets are returned as a tuple of libxml2 Python nodes wrappers. Like
				312	the document, the XPath context need to be freed explicitely, also not that
				313	the result of the XPath query may point back to the document tree and hence
				314	the document must be freed after the result of the query is used.</p>
				315	<h3>xpathext.py:</h3>
				316	<p>This test shows how to extend the XPath engine with functions written in
				317	python:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	318	<pre>import libxml2
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	319
				320	def foo(ctx, x):
				321	return x + 1
				322
				323	doc = libxml2.parseFile("tst.xml")
				324	ctxt = doc.xpathNewContext()
				325	libxml2.registerXPathFunction(ctxt._o, "foo", None, foo)
				326	res = ctxt.xpathEval("foo(1)")
				327	if res != 2:
				328	print "xpath extension failure"
				329	doc.freeDoc()
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	330	ctxt.xpathFreeContext()</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	331	<p>Note how the extension function is registered with the context (but that
				332	part is not yet finalized, ths may change slightly in the future).</p>
				333	<h3>tstxpath.py:</h3>
				334	<p>This test is similar to the previousone but shows how the extension
				335	function can access the XPath evaluation context:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	336	<pre>def foo(ctx, x):
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	337	global called
				338
				339	#
				340	# test that access to the XPath evaluation contexts
				341	#
				342	pctxt = libxml2.xpathParserContext(_obj=ctx)
				343	ctxt = pctxt.context()
				344	called = ctxt.function()
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	345	return x + 1</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	346	<p>All the interfaces around the XPath parser(or rather evaluation) context
				347	are not finalized, but it should be sufficient to do contextual work at the
				348	evaluation point.</p>
				349	<h3>Memory debugging:</h3>
				350	<p>last but not least, all tests starts with the following prologue:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	351	<pre>#memory debug specific
Daniel Veillard	af43f63	2002-03-08 15:05:20 +0000	[diff] [blame]	352	libxml2.debugMemory(1)</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	353	<p>and ends with the following epilogue:</p>
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	354	<pre>#memory debug specific
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	355	libxml2.cleanupParser()
				356	if libxml2.debugMemory(1) == 0:
				357	print "OK"
				358	else:
				359	print "Memory leak %d bytes" % (libxml2.debugMemory(1))
Daniel Veillard	9eb146b	2002-02-21 16:04:51 +0000	[diff] [blame]	360	libxml2.dumpMemory()</pre>
Daniel Veillard	6dbcaf8	2002-02-20 14:37:47 +0000	[diff] [blame]	361	<p>Those activate the memory debugging interface of libxml2 where all
				362	alloacted block in the library are tracked. The prologue then cleans up the
				363	library state and checks that all allocated memory has been freed. If not it
				364	calls dumpMemory() which saves that list in a <code>.memdump</code> file.</p>
				365	<p><a href="bugs.html">Daniel Veillard</a></p>
				366	</td></tr></table></td></tr></table></td></tr></table></td>
				367	</tr></table></td></tr></table>
				368	</body>
				369	</html>