UCA unnecessary collation weight 0000

Philippe Verdy via Unicode unicode at unicode.org
Thu Nov 1 15:13:46 CDT 2018

I'm not speaking just about how collation keys will finally be stored (as
uint16 or bytes, or sequences  of bits with variable length); I'm just
refering to the sequence of weights you generate.
You absolutely NEVER need ANYWHERE in the UCA algorithm any 0000 weight,
not even during processing, or un the DUCET table.

Le jeu. 1 nov. 2018 à 21:08, Markus Scherer <markus.icu at gmail.com> a écrit :

> There are lots of ways to implement the UCA.
> When you want fast string comparison, the zero weights are useful for
> processing -- and you don't actually assemble a sort key.
> People who want sort keys usually want them to be short, so you spend time
> on compression. You probably also build sort keys as byte vectors not
> uint16 vectors (because byte vectors fit into more APIs and tend to be
> shorter), like ICU does using the CLDR collation data file. The CLDR root
> collation data file remunges all weights into fractional byte sequences,
> and leaves gaps for tailoring.
> markus
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