[Development] Utf8 local aware compare

[Knoll Lars]

Hi Marco,

On 11/09/14 13:23, "Bubke Marco" <Marco.Bubke at digia.com> wrote:
>Okay, first the context. I want to write locale aware compare collations
>for a local database which is saving the text in UTF-8. So converting the
>text always with QString::fromUtf8 is a little bit expensive. Under Unix
>strcoll would work but for windows there
> is no UTF-8 collation. One idea around that problem is to convert per
>character to UTF-16 and than compare it. Is there some internal API where
>I could do the conversion per character(not per byte)?

There’s no real way to do this. Collation needs to work on whole strings,
and can’t compare byte by byte. And the platform APIs on Windows, Mac and
ICU are all utf16 based. So the API below wouldn’t help as we’d still have
to convert the string to utf16 before passing it into the platform APIs.

Lars

>
>
>Anyway, best would be:
>
>QCollator 
><http://qt-project.org/doc/qt-5/qcollator.html#QCollator>::compare
><http://qt-project.org/doc/qt-5/qcollator.html#compare>(const char
>*utf8String1, const char *utf8String2,
> size_t size1=-1, size_t size2=-1) const
>
>Thank you, Marco
>
>
>
>