Re: What's your favourite *under_publicized* editing feature of Emacs?

[Oleksandr Gavenko]

On 2011-02-10 0:32, Thien-Thi Nguyen wrote:
> () Oleksandr Gavenko<gavenkoa@gmail.com>
> () Wed, 09 Feb 2011 23:31:15 +0200
>
>     So because of unnecessary work to set text property to well
>     structured data on *all* lines we have slow down instead perform
>     parsing of reference on demand.
>
>     [...]
>
>     Or I am something missing?
>
> You have well-structured data but the compilation (likewise, grep)
> font-locking tries to cope with a more general input.  You can prune
> some elements from ‘compilation-error-regexp-alist’ to help focus the
> font-locking.  Have you tried that?
Yes. I wrote:

(require 'compile)
(setq my-log2-error-regexp-alist
      '(
        ("^\\([^:]+\\):\\([[:digit:]]+\\):" 1 2)
        ))
(define-compilation-mode my-log2-mode "MyLog"
  "Log mode."
  (set (make-local-variable 'compilation-error-regexp-alist)
        my-log2-error-regexp-alist)
  )

And as I describe previously I eval on same 289 KiB long buffer:
(benchmark-run 1 (revert-buffer))
and get: (20.937 1 0.109)

In contrast to test of 'grep-mode' where I get: (22.406 1 0.156)

As I use same regex for derived from compilation mode as for
custom highlighting mode I decide that bottle neck lies
in setting properties to text.

When set only 'face' property - this is fast. But when set 'message'
property it is slow as 'message' is complex structure which must
recalculated on every matching lines.

--
Best regards!