[fpc-devel] Unicode support in RTL - Roadmap

[Michael Schnell]

>>
>
> If Length() would return its value in chars, what length in *bytes* 
> would the following call set:
>
> SetLength(utfstring_1), Length(utfstring_2));
>
I don't really understand your question.

I think would would need to have two different function

UTF8ElementlLength(UTF8String) and UTF8PointLength(UTF8String), first 
giving the string length in code elements (byte) and second giving the 
length in code points (unicode characters),

So UTF8ElementlLength('Ü') would be 2 and UTF8PointLength('Ü') would be 1.

I think we should have a third function Length(UTF8String) that can be 
selected by the user (e.g. via a {$ option to be mapped to wither of the 
two.

The same would be necessary for the SetLength function

e.g.
(1) UTF8ElementSetLength(utfstring_1), UTF8ElementLength(utfstring_2));
or
(2) UTF8PointSetLength(utfstring_1), UTF8PointLength(utfstring_2));

(2) would work as expected if the purpose i to delete all but the first 
n characters in a string.

I don't see a decent use for (1) other than creating a string long 
enough to use as a buffer for e.g. TStream.read.

I do see that there in fact is a compatibility problem when porting old 
code with the setting of UTF8Count=Point.

here

SetLength(utfstring_1), Length(utfstring_2)); would be translated as
UTF8PointSetLength(utfstring_1), UTF8PointLength(utfstring_2));

which does not make sense if UTF8PointLength(utfstring_1) is smaller 
than UTF8PointLength(utfstring_2).

-Michael