Re: [boost] Review Request: Boost.Locale

Subject: Re: [boost] Review Request: Boost.Locale
From: Artyom (artyomtnk_at_[hidden])
Date: 2010-05-24 15:15:01

> 
> Well, that's not exactly true. mbstate_t is defined by the
> C standard, and indeed, it says pretty much nothing about
> its nature, except that it's not an array. But on any
> platform I worked with (including Windows) it's an integer.


Ö¹Under Linux it is structure and AFAIK gcc uses iconv for conversion.

So I'm not sure how safe is to write anything to it.

> I think, it is perfectly fair to assume that it is at least
> a POD and sizeof(mbstate_t) >= 1, which makes it possible
> to store information about surrogate pairs in it.
> 
> The C++ standard does give some hints regarding how the
> conversion state shall be handled by the stream. In
> particular, it specifies that the state will be
> value-initialized at the beginning of the conversion, and it
> will call `shift` at the end of the conversion in order to
> finalize the converted character sequence and return the
> state to its initial value.
> 
> Not that it makes it easier to use mbstate_t with UCI under
> the hood, but it seems possible (theoretically, at least) to
> implement the complete UTF-16 <-> char conversion with
> it.
> 

I was thinking about it but unfortunately standard does not specify
how mbstate_t initialized. If I could assume that it is at leaset
POD filled with zeros I could do something but I actually can't.

At least I didn't find any reference for this.