[Tkinter-discuss] Here's a tough one -- dynamic, multi-line XML syntax highlighting

[Jared Cohen]

Hiya. My current project is an XML editor using the Tkinter.Text widget. 
Using the parsing tools from xml.parsers.expat, I've managed to 
implement a nice system of syntax highlighting when the document is 
first loaded. However, I want the user to be able to edit the text, and 
have the highlightling automatically update to conform to whatever is 
added or deleted. I can easily do this for single-line tags (those that 
start and end on the same line), because then I can just read in that 
one line and use the parser to re-highlight it. But for multiple-line 
tags, like comments or CDATA sections, it's not so easy.

The problem is that the exact location where the user inserts/removes 
text, will determine how the highlighting changes. For example, a 
comment block is delimeted by  <!-- and -->  Now, if the user types new 
text BETWEEN those two tags, nothing changes; the new text gets the 
existing "comment" highlighting that's already there. If they type new 
text on the same line as one of the delimeters, but outside their range, 
it gets no tags at all. But if the new text is INSIDE one of the 
delimeters themselves (making them no longer syntactically valid), then 
the whole comment block needs to get re-highlighted. And I don't know 
how to do that without re-highlighting the WHOLE document all over 
again. When that happens with every single keystroke, it adds up to a 
whole lot of highlighting. There's got to be a better way, but I can't 
think of one. Can anyone help?

And by the way, I already know about the xmltools package from logilab, 
and it might be exactly what I need. However, I'm working on this 
project at my office, not at home; so I have to rely on the sysadmins to 
install new packages. And the xmltools package will require a LOT of 
dependancies, so it doesn't look like it'll be done any time in the near 
future. :-(


P.S. On a totally unrelated note, how do I reply to messages on this 
board and get them to appear in "nested thread" format? Every time I 
reply, it always appears as a new top-level thread!