[Development] QUtf8String{, View}

[Kai Pastor, DG0YT]

Am 23.05.20 um 03:06 schrieb Thiago Macieira:
> On Thursday, 14 May 2020 07:41:45 PDT Marc Mutz via Development wrote:
>> There's only our own lazyness which stands in the way of this better
>> alternative.
> [snip the rest]
>
> Update:
>
> As we're reviewing the changes Lars is making to get rid of QStringRef, Lars,
> Marc and I came to the conclusion that QUtf8StringView is required for Qt 6.0.
> That's because some methods that previously returned QStringRef now return
> QStringView and to retain compatibility with:
>
>      if (xml.attribute("foo") == "bar")
>
> where QXmlStreamReader::attribute() returns QStringView, we really need to
> capture that "bar" as a UTF-8 string and we ought to have optimised UTF-16 to
> UTF-8 comparisons. So we're working on it.
>
> If it had been wrapped in QLatin1String(), there would be no compatibility
> issues, as there already is an operator==() for QStringView/QLatin1String.
>
> There are currently no conclusions on QUtf8String and QAnyString, nor on what
> the APIs should look like.
>
This also needs a solution in the other direction, QXmlStreamWriter: 
This is painfully slow, despite UTF-8 XML, UTF-8 source code (element 
names, attribute names) and data which might be used as - or transformed 
to - UTF-8 directly. Everything needs to go to UTF-16 first (QString), 
and then back to UTF-8. Allocations, Reference counting, no SSO...