Re: [Vala] how can I get the number of unicode points in a string?

[Xu Ming <xm xming gmail com>]

The idea behind the API isn't to fetch the byte at an offset - instead, 
you'll typically fetch the *character* at an offset, and then advance 
the offset by the number of bytes in the character.  In other words, you 
could iterate over the characters in a string using the new 
get_next_char() method like this:
> int i = 0;
> unichar c;
> while (get_next_char(ref i, out c))
>   handle_character(c);
>
> On each loop iteration, the offset (i) will increment by the size of 
> the character c.
>
>     Is it possible to design the string like this:
>     class string
>     {
>     private unichar* buffer;
>     private int* offset_array;
>     ... ...
>     public unichar operator [](const int i)
>     {
>     int offset=offset_array[i];
>     return buffer[offset];
>     }
>     }
>     offset_array stores the offset of utf8 charater by index. It is
>     initialized in constructor or something.
>     Then we can use string[index] with no iteration overhead.
>
>
> That would add lots of overhead (both in time and space) for every 
> string, and would have limited benefit.  Iterating over characters in 
> a string is a common operation, and is both easy and efficient with 
> the current API.  Fetching the n-th character in a string is less 
> often necessary, so it's OK for it to be less efficient.  In the rare 
> case where you really do need random access to characters by index, 
> you could always iterate over all characters in a string and store 
> them in a unichar[] array for that purpose, or you could construct a 
> data structure similar to the one you've outlined above.
>
> adam
That's good. I just installed 0.12.0. I'll test some code and add this 
new method to the tutorial page.
Now string[i] returns a byte by offset i but string.get_char(i) returns 
a character by offset i, if i is in the right position. I really wish 
that the convenient [] operator be used in place of get_char().