mirror of
https://gitlab.gnome.org/GNOME/libxml2.git
synced 2025-10-21 14:53:44 +03:00
252 lines
19 KiB
HTML
252 lines
19 KiB
HTML
<?xml version="1.0" encoding="ISO-8859-1"?>
|
||
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
|
||
<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1" /><link rel="SHORTCUT ICON" href="/favicon.ico" /><style type="text/css">
|
||
TD {font-family: Verdana,Arial,Helvetica}
|
||
BODY {font-family: Verdana,Arial,Helvetica; margin-top: 2em; margin-left: 0em; margin-right: 0em}
|
||
H1 {font-family: Verdana,Arial,Helvetica}
|
||
H2 {font-family: Verdana,Arial,Helvetica}
|
||
H3 {font-family: Verdana,Arial,Helvetica}
|
||
A:link, A:visited, A:active { text-decoration: underline }
|
||
</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://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
|
||
toget updates to this list or to discuss the specific topic of
|
||
libxml2orlibxslt wrappers or bindings:</p><ul><li><a href="http://libxmlplusplus.sourceforge.net/">Libxml++</a>seemsthemost
|
||
up-to-date C++ bindings for libxml2, check the <a href="http://libxmlplusplus.sourceforge.net/reference/html/hierarchy.html">documentation</a>andthe
|
||
<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
|
||
wrapperforlibxml2/libxslt as part of the <a href="http://axkit.com/">AxKitXMLapplication 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
|
||
basedonLibxml2 Perl bindings.</li>
|
||
<li><a href="mailto:dkuhlman@cutter.rexx.com">Dave
|
||
Kuhlman</a>providesanearlier 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
|
||
setofC# libxml2 bindings.</li>
|
||
<li>Petr Kozelka provides <a href="http://sourceforge.net/projects/libxml2-pas">Pascal units
|
||
togluelibxml2</a>with Kylix, Delphi and other Pascal compilers.</li>
|
||
<li>Uwe Fechner also provides <a href="http://sourceforge.net/projects/idom2-pas/">idom2</a>,
|
||
aDOM2implementation for Kylix2/D5/D6 from Borland.</li>
|
||
<li>There is <a href="http://libxml.rubyforge.org/">bindings forRuby</a>and
|
||
libxml2 bindings are also available in Ruby through the <a href="http://libgdome-ruby.berlios.de/">libgdome-ruby</a>modulemaintainedby
|
||
Tobias Peters.</li>
|
||
<li>Steve Ball and contributors maintains <a href="http://tclxml.sourceforge.net/">libxml2 and libxslt
|
||
bindingsforTcl</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>isaneffort
|
||
to create a 100% JAXP-compatible Java wrapper for libxml2andlibxslt as
|
||
part of GNU ClasspathX project.</li>
|
||
<li>Patrick McPhee provides Rexx bindings fof libxml2 and libxslt,
|
||
lookfor<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 inAppleScript
|
||
the XML DOM, XPATH and XSLT. Also includescommands forProperty-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>wrappersthat
|
||
interface libxml2, allowing wxWidgets applications toload/save/editXML
|
||
instances.</li>
|
||
</ul><p>The distribution includes a set of Python bindings, which are
|
||
guaranteedtobe maintained as part of the library in the future, though
|
||
thePythoninterface have not yet reached the completeness of the C API.</p><p>Note that some of the Python purist dislike the default set
|
||
ofPythonbindings, rather than complaining I suggest they have a look at <a href="http://codespeak.net/lxml/">lxml the more pythonic bindings
|
||
forlibxml2and libxslt</a>and <a href="http://codespeak.net/mailman/listinfo/lxml-dev">helpMartijnFaassen</a>complete
|
||
those.</p><p><a href="mailto:stephane.bidoul@softwareag.com">St<EFBFBD>phaneBidoul</a>maintains <a href="http://users.skynet.be/sbi/libxml-python/">aWindows 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
|
||
toautomatea large part of the Python bindings, this includes
|
||
functiondescriptions,enums, structures, typedefs, etc... The Python script
|
||
used tobuild thebindings 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>(andif
|
||
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-pythonmoduledistribution</a>corresponding
|
||
to your installed version oflibxml2 andlibxslt. Note that to install it
|
||
you will need both libxml2and libxsltinstalled and run "python setup.py
|
||
build install" in themodule tree.</li>
|
||
</ul><p>The distribution includes a set of examples and regression tests
|
||
forthepython bindings in the <code>python/tests</code>directory. Here
|
||
aresomeexcerpts 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
|
||
equivalentofxmlParseFile (most of the bindings are automatically generated,
|
||
and thexmlprefix is removed and the casing convention are kept). All node
|
||
seen atthebinding 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
|
||
basedonxmlNodeGetContent() 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 associatedelement in the tree,those may return None in case no such
|
||
linkexists.</li>
|
||
</ul><p>Also note the need to explicitly deallocate documents with
|
||
freeDoc().Reference counting for libxml2 trees would need quite a lot of
|
||
worktofunction properly, and rather than risk memory leaks if
|
||
notimplementedcorrectly it sounds safer to have an explicit function to free
|
||
atree. Thewrapper python objects like doc, root or child are
|
||
themautomatically garbagecollected.</p><h3>validate.py:</h3><p>This test check the validation interfaces and redirection
|
||
oferrormessages:</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(),
|
||
itdefinesa new error handler global to the library. It is used to avoid
|
||
seeingtheerror messages when trying to validate the invalid document.</p><p>The main interest of that test is the creation of a parser
|
||
contextwithcreateFileParserCtxt() and how the behaviour can be changed
|
||
beforecallingparseDocument() . Similarly the informations resulting from
|
||
theparsing phaseare also available using context methods.</p><p>Contexts like nodes are defined as class and the libxml2 wrappers mapstheC
|
||
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 atthelibxml2.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
|
||
onthexmlCreatePushParser() from the C library. The first argument is
|
||
anoptionalSAX callback object, then the initial set of data, the length and
|
||
thename ofthe resource in case URI-References need to be computed by
|
||
theparser.</p><p>Then the data are pushed using the parseChunk() method, the
|
||
lastcallsetting the third argument terminate to 1.</p><h3>pushSAX.py:</h3><p>this test show the use of the event based parsing interfaces. In
|
||
thiscasethe parser does not build a document, but provides callback
|
||
informationasthe 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
|
||
ofentrypoints which can be called by the parser as it makes progresses
|
||
toindicatethe information set obtained. The full set of callback is larger
|
||
thanwhatthe callback class in that specific example implements (see
|
||
theSAXdefinition for a complete list). The wrapper will only call those
|
||
suppliedbythe object when activated. The startElement receives the names of
|
||
theelementand a dictionary containing the attributes carried by this
|
||
element.</p><p>Also note that the reference string generated from the callback
|
||
showsasingle character call even though the string "bar" is passed to
|
||
theparserfrom 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
|
||
evaluateXPathexpression on it. The xpathEval() method execute an XPath query
|
||
andreturnsthe result mapped in a Python way. String and numbers are
|
||
nativelyconverted,and node sets are returned as a tuple of libxml2 Python
|
||
nodeswrappers. Likethe document, the XPath context need to be freed
|
||
explicitly,also not thatthe result of the XPath query may point back to the
|
||
documenttree and hencethe document must be freed after the result of the
|
||
query isused.</p><h3>xpathext.py:</h3><p>This test shows how to extend the XPath engine with functions
|
||
writteninpython:</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
|
||
(butthatpart 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
|
||
theextensionfunction 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 workat
|
||
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 whereallallocated
|
||
block in the library are tracked. The prologue then cleans upthelibrary state
|
||
and checks that all allocated memory has been freed. If notitcalls
|
||
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>
|