Xref: utzoo comp.text.tex:3453 soc.culture.german:1778
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From: dorai@tone.rice.edu (Dorai Sitaram)
Newsgroups: comp.text.tex,soc.culture.german
Subject: Ascii German -> Diacritics
Message-ID: <1990Oct20.042619.10038@rice.edu>
Date: 20 Oct 90 04:26:19 GMT
Sender: news@rice.edu (News)
Organization: Rice University, Houston
Lines: 54

If you're interested in a teensy program that converts "Ascii German"
into "diacritical German", you might want to read this.  As I'm pretty
certain the demand will be rather small, I won't post it.  Send me
email if you want the program.

Description:

\begin{nomenclature}

Ascii German (AG): the 26-letter German (orthography) commonly used on
"regular" keyboards, viz., ae, oe, ue, ss for the umlauted vowels and
eszet.

Diacritical German (DG): the real stuff, viz., what \"a, \"o, \"u, \ss
produce in TeX's output.

\end{nomenclature}

Why?

A lot of people comfortably read and write AG on keyboards instead of
using TeX source (\"a) or even german.sty kind of source ("a).
However, when such text eventually gets converted to something which
allows visible umlauts and eszet, we'd like to convert our AG into the
proper diacritical form.

This is slightly tricky since, although coding DG into AG is 1-1, the
reverse (decoding) isn't.  One certainly can't convert all occurrences
of ae, oe, ue, ss into the corresponding special characters.  E.g.,
Dauer != Da\"ur; wissen != wi{\ss}en; etc.

I brewed a very little lex program "diac" which converts AG into DG
using context information to figure out which ae/oe/ue/ss get
converted.  The output is TeX source style.

There is also an easy way to invoke "diac" as a preprocessor for
LaTeX, so you can write your .tex files in AG style but get 
.dvi output with flawless diacritics.

Except for Masse/Ma{\ss}e. :-] 

Actually, I have very certainly not exhausted all the patterns that
are recognizable, though the present program seems fine on some test
data I have.  Luckily, it's easy to add new patterns (and to know what
patterns to add) in the event of future bloopers.

This program isn't necessarily restricted to German.  It should be
easily modifiable to any other language that uses diacritics and has a
popular or idiosyncratic Ascii encoding.  (E.g., an Indian language in
Ascii w.r.t. any standard representation in Roman diacritics.)
Moreover, as you get the hang of the patterns used, you can devise
your own patterns to get better decodings.

--d