[XML-SIG] HtmlBuilder

Thu, 4 Mar 1999 18:32:13 -0500

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Hi all,

I use a program for which I do not have the source code to convert RTF to
HTML.  I then use xml.dom to reformat it, add navigation bars, fix links,
etc.  Very rarely, the RTF to HTML converter will throw a </A> into a
document without a preceding <A>.  This causes HtmlBuilder to start popping
elements off its stack while looking for the starting <A>, including <BODY>
and <HTML>.  When it runs out of stack it happily continues and the DOM is
created.  Unfortunately, each following element that should have been a
child of <BODY> then becomes a sibling of the <HTML> document element.
This produces an invalid DOM document but no exceptions are thrown.
Eventually I do something with the DOM that calls the method
Node.get_documentElement which raises a HierarchyRequestException because
there is more than one root element.

Since I don't have the source code the RTF to HTML converter, I can't fix
it.  I did however add two lines of code to HtmlBuilder that will allow
these bogus end tags to be ignored.  I hope that the new code can be added
to the CVS tree.

If this were an XML document I would rather raise an exception and reject
the document. XML should be perfectly well formed.  Since it is an HTML
document I am more inclined to fix what can be fixed logically because
there are already so many invalid HTML files in the world.  I often run
into this same problem when processing hand made HTML files.  This
modification might allow the XML-SIG DOM implementation to be used to clean
up the existing HTML mess.

I added the following three lines:

                        if tag not in self.stack:
                                #print "ignoring end tag with no start",
tag
                                break

to the following method of HtmlBuilder:

        def unknown_endtag(self, tag):
                tag = string.upper(tag)
                #print 'ending', tag

                while self.stack:
                        if tag not in self.stack:
                                #print "ignoring end tag with no start",
tag
                                break
                        if tag in self.empties:
                                continue
                        start_tag = self.stack[-1]
                        del self.stack[-1]
                        Builder.endElement(self, start_tag)
                        if start_tag == tag:
                                break

The entire file is attached:
(See attached file: html_builder.py)

Cheers,
Jeff

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