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