Hi Matt,
Your error was not a fundamental error regarding XSLT. Rather, you were
attempting to get at implementation classes by casting, which is always a
bad thing to do. The implementations are hidden because you shouldn't rely
on implementation-level behavior or APIs at the application level.
XalanDocumentBuilder was designed as an abstraction to allow a source tree
to be built through SAX events, rather than by parsing a document. You
were mis-using it by casting to get at implementation classes.
The other person was trying to modify the source tree, which is explicitly
forbidden by the XSLT processing model. There is nothing in the XSLT
recommendation that describes how this source tree is built, or any other
such implementation-level details.
Dave
Matthew James
Hanson To:
[email protected]
<matthew.hanson@ cc: (bcc: David N
Bertoni/CAM/Lotus)
wcom.com> Subject: RE: createElement()
inside external function
segfaults
12/11/2001 02:13
PM
Using the SAX calls and const methods will be no problem! I assume, then,
that my original strategy of building up a tree was actually a
misunderstanding of XSLT, similar to the other post. What fundamental
knowledge was I missing about XSLT?
Thanks!
Matt Hanson!
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
Sent: Tuesday, December 11, 2001 10:40 AM
To: [email protected]
Subject: RE: createElement() inside external function segfaults
This is the exact same issue. XalanSourceTreeDocument does not support the
standard DOM factory calls for creating nodes and modifying the tree. You
need to build it through SAX events, because the tree must be built in
document order. Allowing standard DOM calls would also allow random
construction of the tree, which is not supported.
Note that this does not affect _read-only_ access to the tree through DOM
calls. This can be summarized by stating that most const methods of the
XalanDOM hierarchy are supported, while _none_ of the non-const ones are
supported.
You can easily fix your code by calling the startElement() and endElement()
member functions of XalanDocumentBuild, rather than creating a
XalanSourceTreeElement instance and appending it.
Dave
Matthew James
Hanson To:
[email protected]
<matthew.hanson@ cc: (bcc: David N
Bertoni/CAM/Lotus)
wcom.com> Subject: RE: createElement()
inside external function
segfaults
12/11/2001 11:53
AM
This issue may relate to a technique that I have been trying, but NOT part
of an extension function. I have been trying to avoid using SAX events
with
XalanSourceTreeContentHandler. Rather, I was hoping I could have access to
the underlying XalanSourceTreeDocument returned from
XalanDefaultDocumentBuilder->getDocument(). No exceptions are thrown, but
XalanSourceTreeDocument->createNodeElement(...) doesn't output my data.
Here is the code:
AttributesImpl attrs;
XalanDOMString elemNm, attrNm, attrVal;
const XalanDOMString attrType("CDATA");
XalanDocumentBuilder* const docBldr =
theXalanTransformer.createDocumentBuilder();
if (docBldr)
{
XalanSourceTreeDocument * doc(static_cast <
XalanSourceTreeDocument * >
(docBldr->getDocument()));
if (doc)
{
std::cout << "have
XalanSourceTreeDocument\n";
elemNm = "name1";
attrNm = "attr1Nm";
attrVal = "attr1Val";
attrs.addAttribute(c_wstr(attrNm),
c_wstr(attrType), c_wstr(attrVal));
attrNm = "attr2Nm";
attrVal = "attr2Val";
attrs.addAttribute(c_wstr(attrNm),
c_wstr(attrType), c_wstr(attrVal));
XalanSourceTreeElement *
element(doc->createElementNode(attrNm.c_str(),
attrs));
doc->appendChildNode(element);
}
}
Am I also misunderstanding the usage of these classes. I hope really hope
to have access to the underlying tree so that I can get attributes, values,
of an element to be used by its child elements.
Thanks!!!
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]
Sent: Tuesday, December 11, 2001 9:30 AM
To: [email protected]
Subject: Re: createElement() inside external function segfaults
It's not a bug in Xalan, it's a bug in your application and your
understanding of XSLT.
You are not allowed to modify the source tree in any way, including
creating new nodes. The function you're calling is throwing an exception
which you're not catching. See the class XalanDOMException and the source
code for XalanSourceTreeDocument for more information on what's being
thrown.
Currently, there's no way in Xalan-C to create new nodes in an extension
function. We can certainly make something like that available, but it
wouldn't be through DOM APIs. Insteand, it would be through getting a SAX
handler and sending events. If this functionality is important to you,
then we should discuss the best way to implement this.
Dave
Edwin Pratomo
<[EMAIL PROTECTED] To:
[email protected]
.org> cc:
Sent by: Subject: createElement()
inside external function segfaults
[EMAIL PROTECTED]
m
12/11/2001 09:56
AM
Hi,
I tried to create new elements inside an external function, but
createElement() segfaults:
virtual XObjectPtr
execute(
XPathExecutionContext& executionContext,
XalanNode* context,
int /* opPos */,
const XObjectArgVectorType& args)
{
XalanDocument *doc = context->getOwnerDocument();
XalanElement *new_node = doc->createElement(XalanDOMString("foo"));
...
Is this a bug? any workaround?
rgds,
Edwin.
--
CPAN home: http://search.cpan.org/search?author=edpratomo
