Re: [Nano-devel] aggressive C color highlighting

[Alexey Toptygin]

On Thu, 3 Aug 2006, David Lawrence Ramsey wrote:

> > 1) Apply all expressions to the current character pointer and
> > increment to the end of the match or to the next character when there
> > is no match. This method is quite simple and will give a significant
> > speed boost.
> >
> > 2) Use the same technique as in the first method but store all matches
> > in a list and colorize the text using the list. The list must be
> > rebuilt each time the file is modified. This method uses more memory
> > to store the list but gives a huge speed increase when only viewing a
> > file and no loss in speed compared to the first method.
>
> I'm a bit nervous about method 2, as one of the limitations of the
> current code is that responsiveness is a lot lower when modifying a
> heavily colorized file, and from your description, it sounds as though
> it'd make things worse.  Or am I misunderstanding something, since I'm
> not exactly a guru when it comes to the color code?

2 should be faster than 1 even when editing, but slower than no coloring. 
If you can search the list quickly by line number, you only need to 
re-apply regexes to the text starting at the end of the last matched area 
that was entirely before the edited area, and ending at the end of the 
first matched area that is both a) entirely after the edited area and b) 
identical before and after the edit.

For most edits, this means only 1-2 matched areas need to be updated in 
the list. The same quick list search can be used to get the matched areas 
that need to be highlighted on the screen about to be drawn. Finally, you 
can choose not to populate the list for areas after the one under edit.

The only thing that is still slow is starting to edit at the end of a long 
file - you need to scan linearly from the start or you're not guaranteed 
to get the propper matches. If this ever gets really terrible, we can give 
it a timeout, and then ask the user whether to continue or abort, like 
less does when counting line numbers.

                        Alexey