bug#13041: 24.2; diacritic-fold-search

[Lewis Perin]

This is not a bug report but a feature request, so I am omitting
diagnostic information.

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.)

I’m sure that maintaining the core of Emacs is a big job, and I’m
grateful for the skill and effort that go into that task, including
your consideration of this request!

/Lew
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Lew Perin | perin@acm.org | http://babelcarp.org