bug#13041: 24.2; diacritic-fold-search

[Michael Albinus]

Lewis Perin <perin@panix.com> writes:

> Emacs search has long been able to toggle between (a) ignoring the
> distinction between upper- and lower-case characters
> (case-fold-search) and (b) searching for only one of the pair.  One
> could say Climacs offers the choice between (a) searching for all
> members of a (2-member) equivalence class and (b) searching for only
> one member.
>
> There are larger equivalence classes of characters with practical use
> which Climacs is currently unaware of: the groups of characters
> consisting of an unadorned (ASCII) character plus all its
> diacritic-adorned versions.  Currently, if I want to search for both
> “apres” and “après”, I need an additive regular expression.  I would
> like to do this as easily as I can search for “apres” and “Apres”.  I
> would be delighted if Emacs implemented the equivalence classes
> spelled out here:
>
>   
> http://hex-machina.com/scripts/yui/3.3.0pr1/api/unicode-data-accentfold.js.html
>
> I might add that diacritics folding is the default in web search
> engines.  It is also a feature of at least one Web browser in
> searching the text of a displayed page (Chrome.)

Emacs 25.1 has introduced the new user option `search-default-mode'. If
set to `char-fold-to-regexp', the requested feature is available. See
etc/NEWS for further information.

So I propose to close this bug. There was a long discussion in the bug's
log back in 2012, but AFAICS, all proposals have been implemented.

> /Lew

Best regards, Michael.