[Beaver-devel] The future of syntax highlighting

[Michael Terry]

Hello again, Leslie.

I wanted to open a dialog about possible futures of syntax highlighting 
(syhi).  The current system, as I mentioned in a previous email, is 
broken up into two algorithms.  One is designed for speed, the other for 
correctness.

Each, though, basically goes through the text, looking for delimiters 
and looks up stuff between delimiters in a hash table of keywords.

Now, this algorithm seems simple enough to me, and I can't think of a 
fundamentally different way to do it.  Yet, it doesn't seem fast enough. 
 It's fine for small files or just highlighting as you type, but when 
one opens a large file, Beaver can take a bit to highlight it.

The way I solved this was to update the GUI as we highlight, if we take 
over half a second to highlight.  This slows down total highlight time, 
but increases perceived responsiveness.  This solution seems to work ok.

However, it might be worthwhile to acquire a better solution.  For 
example, we were talking about Scintilla.  SciTE, based on Scintilla, 
does a tremendously fast job of highlighting (at least, I've never 
noticed the highlighting, which is arguably our goal -- that the user 
never notices it; it just happens).  I've spent a moment looking at the 
code, and it has specific highlight engines for different languages. 
This might be a consideration for us.

I'm not sure if we want to actually use Scintilla ourselves, since it is 
written in C++, seems tied to GtkTextisms (rather than GtkTextViewisms), 
and uses a different signaling model than GTK+.

I'm not sure what we could do differently with a language-specific 
parser though.  We would still have to go through and look for 
delimiters.  We would still have to look up keywords in some data 
structure (a hash table still seems optimal).  The wordfile system we 
use now is just a generic way of describing a language.  I don't think 
we are losing speed because of this genericness.

Do you have any ideas on amazing syhi algorithms or ways to outsource 
the issue?  How do you feel about the current syhi speed?

-mt

pgpTTU5GXesx2.pgp
Description: PGP signature