Re: bug-reference-prog-mode slows down CC Mode's scrolling by ~7%

[Stefan Monnier]

> Note that it is difficult to use the jit-lock-bounds returned by a
> subsequent function, if they exceed the bounds returned by the first
> function.  To do this safely, we would have to re-run all the previous
> jit-lock-functions on the newly enlarged region.  This would be clumsy,
> and wouldn't fit in well with our current scheme.

That's not the only option, tho.  We could also do the following:

- mark with `fontified` the intersection of all the
  `jit-lock-bounds` received (like we do now).

- mark the rest of those bounds with a new property which keeps track of
  those fontification functions that did not operate on them, so next
  time we need to jit-lock those pieces we only run the corresponding
  subset of functions.

I'm not claiming it would work better, tho: it would be more lazy
(more "jit") but it would also imply extra complexity when jitting
because we'd need to look for this new property and obey it.

> As for "fighting" to be the first function in j-l-f, I don't think that
> should be a problem.  We can document the new &optional parameter to
> jit-lock-register (not yet implemented) to say "don't use this unless
> you really know what you're doing".

Indeed.


        Stefan