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