Re: Unicode string comparision functions

[Shark8 <onewingedshark@gmail.com>]

On Thursday, November 12, 2015 at 12:46:22 PM UTC-7, Randy Brukardt wrote:
> "Shark8" wrote in message 
> 
> >I thought I had come across a unicode Equals_Case_Insensitive
> >(and less than) for unicode using Wide_Wide_Strings some time
> >ago, but I cannot seem to find them again; am I misremembering,
> >or were they in a really odd place?
> 
> Not an odd place, but they have their own subclause (A.4.10).

Thank you for the ref.

> 
> >For this particular application I would rather use Wide_Wide_String than
> > Wide_String so I wouldn't have to worry about invalid character 
> > [sequences]
> > for the non-ASCII characters. (And, while UTF-8 encoded strings have the
> > nice property of being endian agnostic, they still have that property.) --  
> > But I
> > suppose the main thing is to have a good case insensitive compare such 
> > that
> > PRUSSIAN and Prußian are considered equal.
> 
> Sorry, the language-defined equality won't do that. It uses 
> "locale-independent simple case folding", which means that strings of 
> different lengths are always different. (That's the same case comparison 
> that's used for Ada identifiers.)
> 
> The much more complex "locale-independent full case folding" is not provided 
> by the language, we didn't want to inflict that level of pain on Ada 
> implementers (especially as the need was unclear).

I can see why, and certainly don't begrudge that decision -- unicode is, IMO, a terrible 'solution' to the problem of multiple languages.

I thought I read something in the rationale that implied the full case folding was to be used, at least with respect identifiers in Ada's own source-code... and so mistakenly thought the Equal_Case_Insensitive would do so (after all, if the compiler itself requires that functionality there's little reason not to provide access to it).

> 
> The AARM note A.4.10(3.a/3) gives a bit of background.

I'll have to read that.

Thank you.