bug#11948: 24.1.50; word-wrap should allow wrapping at all breaking space characters, not just space and tab

[martin rudalics]

>> The Unicode line breaking algorithm is probably the place to go:
>>
>> http://unicode.org/reports/tr14/
>
> Thanks, but that's not what I meant.  Implementing UAX#14 in full is
> an effort similar (although smaller) to what was required for
> implementing UAX#9, the Unicode Bidirectional Algorithm.  The main
> problem is that, like with UAX#9, the algorithms in UAX#14 are
> specified assuming that text is processed for display in batches.  By
> contrast, the Emacs display engine, which implements word-wrap,
> examines and processes characters one by one.  So one needs to
> "serialize", so to speak, the UAX#14 algorithms so that its decisions
> could be made on a character-by-character basis.
>
> I think just supporting more characters from LineBreak.txt on which to
> wrap should be a good start, and much easier than implementing UAX#14.
> Even for that, we will need an efficient char-table for the related
> properties, probably via the uniprop_table machinery, like what bidi.c
> uses.  Otherwise, referencing the ordinary char-tables of character
> properties for each character we display could slow down redisplay too
> much.

While you're all there: If anybody has any idea how to support a
practical and simplified version of collation, see

http://www.unicode.org/reports/tr10/

in emacs, I'd be all ears.

martin