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Re: Error with fill-paragraph in my own major mode
From: |
Stefan Monnier |
Subject: |
Re: Error with fill-paragraph in my own major mode |
Date: |
Thu, 31 Jan 2008 10:25:21 -0500 |
User-agent: |
Gnus/5.13 (Gnus v5.13) Emacs/23.0.50 (gnu/linux) |
> Nevertheless I must admit that I don't really grok that code in
> fill.el. What is that (concat "\0" commark "a") good for?
The code in fill.el is fiendishly subtle (I should know, I wrote it).
This (concat "\0" commark "a") thingy is there to check whether or not
we can build a stricter comment-start-skip that will only match
a specific comment-marker rather than any comment marker.
E.g. we're looking at a line that starts with "//" and we want to find
all the lines that start with "//" and refill them together, but we
don't want to consider lines that start with "///" or "/*".
The `concat' builds a test case to check whether the comment-start-skip
regexp is restricting the comment starter to be in column 0 (as is the
case in Fortran), and whether a space (or similar) char is needed
between the comment-marker and the comment's content (as is the case
with Texinfo's "@c" and Basic's "Rem").
That's what the comment tries to explain:
;; A regexp more specialized than comment-start-skip, that only
;; matches the current commark rather than any valid commark.
;;
;; The specialized regexp only works for "normal" comment
;; syntax, not for Texinfo's "@c" (which can't be immediately
;; followed by word-chars) or Fortran's "C" (which needs to be
;; at bol), so check that comment-start-skip indeed allows the
;; commark to appear in the middle of the line and followed by
;; word chars. The choice of "\0" and "a" is mostly arbitrary.
-- Stefan