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| </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 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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.explain.com.au/oss/libxml2xslt.html">MacOsX binaries</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 forlibxml2, |
| the list below is not exhaustive. Please contact the <a href="http://mail.gnome.org/mailman/listinfo/xml-bindings">xml-bindings@gnome.org</a>(<a href="http://mail.gnome.org/archives/xml-bindings/">archives</a>) inorder to |
| get updates to this list or to discuss the specific topic of libxml2or |
| libxslt wrappers or bindings:</p><ul><li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a>seems |
| themost up-to-date C++ bindings for libxml2, check the <a href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a>and |
| the <a href="http://cvs.sourceforge.net/cgi-bin/viewcvs.cgi/libxmlplusplus/libxml%2b%2b/examples/">examples</a>.</li> |
| <li>There is another <a href="http://libgdome-cpp.berlios.de/">C++ |
| wrapperbased on the gdome2 bindings</a>maintained by Tobias Peters.</li> |
| <li>and a third C++ wrapper by Peter Jones <pjones@pmade.org> |
| <p>Website: <a href="http://pmade.org/pjones/software/xmlwrapp/">http://pmade.org/pjones/software/xmlwrapp/</a></p> |
| </li> |
| <li><a href="http://mail.gnome.org/archives/xml/2001-March/msg00014.html">MattSergeant</a>developed |
| <a href="http://axkit.org/download/">XML::LibXSLT</a>, a Perl wrapper |
| forlibxml2/libxslt as part of the <a href="http://axkit.com/">AxKit |
| XMLapplication server</a>.</li> |
| <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 |
| onLibxml2 Perl bindings.</li> |
| <li><a href="mailto:dkuhlman@cutter.rexx.com">Dave Kuhlman</a>provides |
| anearlier version of the libxml/libxslt <a href="http://www.rexx.com/~dkuhlman">wrappers for Python</a>.</li> |
| <li>Gopal.V and Peter Minten develop <a href="http://savannah.gnu.org/projects/libxmlsharp">libxml#</a>, a set |
| ofC# libxml2 bindings.</li> |
| <li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units to |
| gluelibxml2</a>with Kylix, Delphi and other Pascal compilers.</li> |
| <li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>, a |
| DOM2implementation for Kylix2/D5/D6 from Borland.</li> |
| <li>There is <a href="http://libxml.rubyforge.org/">bindings for |
| Ruby</a>and libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a>modulemaintained |
| by Tobias Peters.</li> |
| <li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt bindings |
| forTcl</a>.</li> |
| <li>libxml2 and libxslt is the default XML library for PHP5.</li> |
| <li><a href="http://savannah.gnu.org/projects/classpathx/">LibxmlJ</a>isan |
| effort to create a 100% JAXP-compatible Java wrapper for libxml2 |
| andlibxslt as part of GNU ClasspathX project.</li> |
| <li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt, look |
| for<a href="http://www.interlog.com/~ptjm/software.html">RexxXML</a>.</li> |
| <li><a href="http://www.satimage.fr/software/en/xml_suite.html">Satimage</a>provides |
| <a href="http://www.satimage.fr/software/en/downloads_osaxen.html">XMLLibosax</a>. |
| This is an osax for Mac OS X with a set of commands toimplement in |
| AppleScript the XML DOM, XPATH and XSLT. Also includescommands for |
| Property-lists (Apple's fast lookup table XML format.)</li> |
| <li>Francesco Montorsi developped <a href="https://sourceforge.net/project/showfiles.php?group_id=51305&package_id=45182">wxXml2</a>wrappers |
| that interface libxml2, allowing wxWidgets applications toload/save/edit |
| XML instances.</li> |
| </ul><p>The distribution includes a set of Python bindings, which are guaranteedto |
| be maintained as part of the library in the future, though the |
| Pythoninterface have not yet reached the completeness of the C API.</p><p>Note that some of the Python purist dislike the default set of |
| Pythonbindings, rather than complaining I suggest they have a look at <a href="http://codespeak.net/lxml/">lxml the more pythonic bindings for |
| libxml2and libxslt</a>and <a href="http://codespeak.net/mailman/listinfo/lxml-dev">help |
| MartijnFaassen</a>complete those.</p><p><a href="mailto:stephane.bidoul@softwareag.com">Stéphane |
| Bidoul</a>maintains <a href="http://users.skynet.be/sbi/libxml-python/">a |
| Windows portof the Python bindings</a>.</p><p>Note to people interested in building bindings, the API is formalized as<a href="libxml2-api.xml">an XML API description file</a>which allows toautomate |
| a large part of the Python bindings, this includes functiondescriptions, |
| enums, structures, typedefs, etc... The Python script used tobuild 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-pythonRPM</a>(and |
| if needed the <a href="http://rpmfind.net/linux/rpm2html/search.php?query=libxslt-python">libxslt-pythonRPM</a>).</li> |
| <li>Otherwise use the <a href="ftp://xmlsoft.org/libxml2/python/">libxml2-pythonmodule |
| distribution</a>corresponding to your installed version oflibxml2 and |
| libxslt. Note that to install it you will need both libxml2and libxslt |
| installed and run "python setup.py build install" in themodule tree.</li> |
| </ul><p>The distribution includes a set of examples and regression tests for |
| thepython bindings in the <code>python/tests</code>directory. Here are |
| someexcerpts 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 |
| |
| doc = libxml2.parseFile("tst.xml") |
| if doc.name != "tst.xml": |
| print "doc.name failed" |
| sys.exit(1) |
| root = doc.children |
| if root.name != "doc": |
| print "root.name failed" |
| sys.exit(1) |
| child = root.children |
| if child.name != "foo": |
| print "child.name failed" |
| sys.exit(1) |
| doc.freeDoc()</pre><p>The Python module is called libxml2; parseFile is the equivalent |
| ofxmlParseFile (most of the bindings are automatically generated, and the |
| xmlprefix is removed and the casing convention are kept). All node seen at |
| thebinding level share the same subset of accessors:</p><ul><li><code>name</code>: returns the node name</li> |
| <li><code>type</code>: returns a string indicating the node type</li> |
| <li><code>content</code>: returns the content of the node, it is based |
| onxmlNodeGetContent() and hence is recursive.</li> |
| <li><code>parent</code>, <code>children</code>, |
| <code>last</code>,<code>next</code>, <code>prev</code>, |
| <code>doc</code>,<code>properties</code>: pointing to the associated |
| element in the tree,those may return None in case no such link |
| exists.</li> |
| </ul><p>Also note the need to explicitly deallocate documents with freeDoc() |
| .Reference counting for libxml2 trees would need quite a lot of work |
| tofunction properly, and rather than risk memory leaks if not |
| implementedcorrectly it sounds safer to have an explicit function to free a |
| tree. Thewrapper python objects like doc, root or child are them |
| automatically garbagecollected.</p><h3>validate.py:</h3><p>This test check the validation interfaces and redirection of |
| errormessages:</p><pre>import libxml2 |
| |
| #deactivate error messages from the validation |
| def noerr(ctx, str): |
| pass |
| |
| libxml2.registerErrorHandler(noerr, None) |
| |
| ctxt = libxml2.createFileParserCtxt("invalid.xml") |
| ctxt.validate(1) |
| ctxt.parseDocument() |
| doc = ctxt.doc() |
| valid = ctxt.isValid() |
| doc.freeDoc() |
| if valid != 0: |
| print "validity check failed"</pre><p>The first thing to notice is the call to registerErrorHandler(), itdefines |
| a new error handler global to the library. It is used to avoid seeingthe |
| error messages when trying to validate the invalid document.</p><p>The main interest of that test is the creation of a parser context |
| withcreateFileParserCtxt() and how the behaviour can be changed before |
| callingparseDocument() . Similarly the informations resulting from the |
| parsing phaseare also available using context methods.</p><p>Contexts like nodes are defined as class and the libxml2 wrappers maps |
| theC function interfaces in terms of objects method as much as possible. |
| Thebest to get a complete view of what methods are supported is to look at |
| thelibxml2.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 |
| |
| ctxt = libxml2.createPushParser(None, "<foo", 4, "test.xml") |
| ctxt.parseChunk("/>", 2, 1) |
| doc = ctxt.doc() |
| |
| doc.freeDoc()</pre><p>The context is created with a special call based on |
| thexmlCreatePushParser() from the C library. The first argument is an |
| optionalSAX callback object, then the initial set of data, the length and the |
| name ofthe 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 |
| callsetting 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 |
| casethe parser does not build a document, but provides callback information |
| asthe parser makes progresses analyzing the data being provided:</p><pre>import libxml2 |
| log = "" |
| |
| class callback: |
| def startDocument(self): |
| global log |
| log = log + "startDocument:" |
| |
| def endDocument(self): |
| global log |
| log = log + "endDocument:" |
| |
| def startElement(self, tag, attrs): |
| global log |
| log = log + "startElement %s %s:" % (tag, attrs) |
| |
| def endElement(self, tag): |
| global log |
| log = log + "endElement %s:" % (tag) |
| |
| def characters(self, data): |
| global log |
| log = log + "characters: %s:" % (data) |
| |
| def warning(self, msg): |
| global log |
| log = log + "warning: %s:" % (msg) |
| |
| def error(self, msg): |
| global log |
| log = log + "error: %s:" % (msg) |
| |
| def fatalError(self, msg): |
| global log |
| log = log + "fatalError: %s:" % (msg) |
| |
| handler = callback() |
| |
| ctxt = libxml2.createPushParser(handler, "<foo", 4, "test.xml") |
| chunk = " url='tst'>b" |
| ctxt.parseChunk(chunk, len(chunk), 0) |
| chunk = "ar</foo>" |
| ctxt.parseChunk(chunk, len(chunk), 1) |
| |
| reference = "startDocument:startElement foo {'url': 'tst'}:" + \ |
| "characters: bar:endElement foo:endDocument:" |
| if log != reference: |
| print "Error got: %s" % log |
| print "Expected: %s" % reference</pre><p>The key object in that test is the handler, it provides a number of |
| entrypoints which can be called by the parser as it makes progresses to |
| indicatethe information set obtained. The full set of callback is larger than |
| whatthe callback class in that specific example implements (see the |
| SAXdefinition for a complete list). The wrapper will only call those supplied |
| bythe object when activated. The startElement receives the names of the |
| elementand a dictionary containing the attributes carried by this element.</p><p>Also note that the reference string generated from the callback shows |
| asingle character call even though the string "bar" is passed to the |
| parserfrom 2 different call to parseChunk()</p><h3>xpath.py:</h3><p>This is a basic test of XPath wrappers support</p><pre>import libxml2 |
| |
| doc = libxml2.parseFile("tst.xml") |
| ctxt = doc.xpathNewContext() |
| res = ctxt.xpathEval("//*") |
| if len(res) != 2: |
| print "xpath query: wrong node set size" |
| sys.exit(1) |
| if res[0].name != "doc" or res[1].name != "foo": |
| print "xpath query: wrong node set value" |
| sys.exit(1) |
| doc.freeDoc() |
| ctxt.xpathFreeContext()</pre><p>This test parses a file, then create an XPath context to evaluate |
| XPathexpression on it. The xpathEval() method execute an XPath query and |
| returnsthe result mapped in a Python way. String and numbers are natively |
| converted,and node sets are returned as a tuple of libxml2 Python nodes |
| wrappers. Likethe document, the XPath context need to be freed explicitly, |
| also not thatthe result of the XPath query may point back to the document |
| tree and hencethe 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 |
| inpython:</p><pre>import libxml2 |
| |
| def foo(ctx, x): |
| return x + 1 |
| |
| doc = libxml2.parseFile("tst.xml") |
| ctxt = doc.xpathNewContext() |
| libxml2.registerXPathFunction(ctxt._o, "foo", None, foo) |
| res = ctxt.xpathEval("foo(1)") |
| if res != 2: |
| print "xpath extension failure" |
| doc.freeDoc() |
| ctxt.xpathFreeContext()</pre><p>Note how the extension function is registered with the context (but |
| thatpart 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 |
| extensionfunction can access the XPath evaluation context:</p><pre>def foo(ctx, x): |
| global called |
| |
| # |
| # test that access to the XPath evaluation contexts |
| # |
| pctxt = libxml2.xpathParserContext(_obj=ctx) |
| ctxt = pctxt.context() |
| called = ctxt.function() |
| return x + 1</pre><p>All the interfaces around the XPath parser(or rather evaluation) |
| contextare not finalized, but it should be sufficient to do contextual work |
| at theevaluation point.</p><h3>Memory debugging:</h3><p>last but not least, all tests starts with the following prologue:</p><pre>#memory debug specific |
| libxml2.debugMemory(1)</pre><p>and ends with the following epilogue:</p><pre>#memory debug specific |
| libxml2.cleanupParser() |
| if libxml2.debugMemory(1) == 0: |
| print "OK" |
| else: |
| print "Memory leak %d bytes" % (libxml2.debugMemory(1)) |
| libxml2.dumpMemory()</pre><p>Those activate the memory debugging interface of libxml2 where |
| allallocated block in the library are tracked. The prologue then cleans up |
| thelibrary state and checks that all allocated memory has been freed. If not |
| itcalls 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> |
