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From: Nicolas Goaziou <n.goaziou@gmail.com>
To: Org Mode List <emacs-orgmode@gnu.org>
Subject: [RFC] Alternative to sub/superscript regexp
Date: Mon, 25 Nov 2013 18:14:27 +0100	[thread overview]
Message-ID: <87wqjw8kuk.fsf@gmail.com> (raw)

Hello,

For the record `org-match-substring-regexp' is a variation on:

"\\(\\S-\\)\\([_^]\\)\\(\\(?:\\*\\|[-+]?[^-+*!@#$%^_ \t\r\n,:\"?<>~;./{}=()]+\\)\\)\\)"

I think it is a bit convoluted and therefore difficult to predict. For
example, as recent bug report showed, you may tend to interpret
a_b[fn:1] as

   a_{b}[fn:1]

but, in fact, it is equivalent to

   a_{b[fn}:1]

Of course, we can prevent this by forbidding "[" and "]" in the last
part of the regexp. But I wonder if there's something better to do.

The idea behind this regexp is that we should be able to write simple
sub/superscript, including numbers and entities, without requiring curly
braces (see `org-use-sub-superscripts' docstring for details). Maybe
something like the following could be an interesting alternative:

  "\\(\\S-\\)\\([_^]\\)\\(\\*\\|[+-]?\\(?:\\w\\|[0-9.,\\]\\)*\\(\\w\\|[0-9]\\)\\)"

That is, without braces, either an asterisk or any combination of word,
number, dot, comma and backslash characters, which may start with either
a plus or a minus sign but cannot end with either a dot or a comma.

I find it arguably more predictable (no inverted class). Also, we "gain"
the following:

  a^3.14. <=> a^{3.14}.

At the moment, a^3.14. <=> a^{3}.14.

What do you think?


Regards,

-- 
Nicolas Goaziou

             reply	other threads:[~2013-11-25 17:14 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2013-11-25 17:14 Nicolas Goaziou [this message]
2013-11-25 17:45 ` [RFC] Alternative to sub/superscript regexp Nick Dokos
2013-11-25 21:53 ` Rasmus
2013-11-26  9:20 ` Carsten Dominik
2013-11-26 16:46   ` Nicolas Goaziou
2013-12-18 22:13     ` Nicolas Goaziou
2014-01-11 23:18       ` Nicolas Goaziou

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