Re: Questions about how to implement pickles/utf8.pk

[Mohammad-Reza Nabipoor]

Hi, Jose.

Thanks for your answers :+1:


On Thu, Sep 17, 2020 at 12:58:05AM +0200, Jose E. Marchesi wrote:
> I would use something in this spirit:
>
> deftype UTF8_CodePoint = uint<21>;
>
> deftype UTF8 =
>  struct
>  {
>    byte head;
>
>    defvar bytes
>      = (head > 0x11110000 ? 4
>         : head > 0x11100000 ? 3
>         : head > 0x11000000 ? 2
>         : 1);
>
>    byte[bytes - 1] tail;
>
>    method get_value = UTF8_CodePoint:
>      {
>        defvar size = tail'size + 1;
>
>        [... decode value from head and bytes and return it ...]
>      }
>
>    method set_value = (UTF8_CodePoint value) void:
>      {
>        [... set head and tail ...]
>      }
>
>    method _print = void:
>      {
>        printf ("#<%v>", get_value)
>      }
>  };

:+1:


> > ## Question 4
> >
> > I cannot write `utf8_encode` function for `UTF8_1`, because union construction
> > does not work (like the problem for pinned structs [Bug 26527][2]).
>
> I am not aware of any problem with union constructors.  How they don't
> work?

I mean field initialization doesn't work (like in pinned structs).

```
(poke) UTF8_1 {d2=[0xd8UB, 0xb3UB]}
UTF8_1 {d1=[0x0UB]}
```


Regards,
Mohammad-Reza