Re: [boost] Interest in super string class?

From: Martin Wille (mw8329_at_[hidden])
Date: 2006-07-06 02:32:05

Joel de Guzman wrote:

>> But it might be not: the question of what the result of
>> to_upper(to_lower(to_upper(rng))) is supposed to be is not trivial at
>> all.
> 
> The result will be a view. Then, if it's done correctly, ideally,
> the view transformations can collapse the view. IOTW, this:
> 
>      to_lower_view<to_upper_view<range> >
> 
> will be optimized to:
> 
>      to_lower_view<range>

Hmm, I'm not convinced of that.

  some_container tmp(to_upper_view(rng));
  to_lower_view(tmp);

would return something different than

  to_lower_view(to_upper_view(rng))

in languages which do not have a homomorphous characterwise mapping
between lowercase and uppercase spelling (e.g. german:  ß -> SS, but S
-> s). For the same reason, a locale-aware to_upper_view would not be as
trivial as one would think at first. (Not overly complex, either, probably).

The collapsing views would produce a better quality output in the case
of ß, but I'm not sure the behaviour of compiletime composition
should differ from the behaviour of the runtime composition.

Regards,
m
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