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Re: the discussion so far

This page is part of the web mail archives of SRFI 75 from before July 7th, 2015. The new archives for SRFI 75 contain all messages, not just those from before July 7th, 2015.



At Sat, 16 Jul 2005 15:05:06 +0200, Jorgen Schaefer wrote:
> In contrast, case folding is available for Unicode as a simple
> table which maps codepoints to the case-folded variant. There are
> two tables: The simple case folding maps a single codepoint to a
> single codepoint, while the full case folding table maps a single
> codepoint to one or more codepoints.

Thank you for this clarification (for repeating and expanding it,
actually; I had not yet worked through your earlier message).

So, the `char-ci' operations should use the "simple case folding" table
from CaseFolding.txt, and the `string-ci' operations should use the
"full case folding" table from CaseFolding.txt. After folding, the
comparison result is determined character-by-character.

Meanwhile, `string-upcase' and `string-downcase' reflect the same
improved handling at the string level (compared to the character level)
by using SpecialCasing.txt in addition to UnicodeData.txt.

Have I got that right?

> Since Unicode support requires such lookup tables for about
> anything - including downcasing -, using the case folding table is
> not much of an extra burden.

Yes, I agree.

Thanks,
Matthew