Rainer Deyke wrote:
Andrei Alexandrescu wrote:
One idea I've had for a while was to have a universal string type:
struct UString {
union {
char[] utf8;
wchar[] utf16;
dchar[] utf32;
}
enum Discriminator { utf8, utf16, utf32 };
Discriminator kind;
IntervalTree!(size_t) skip;
...
}
The IntervalTree stores the skip amounts that must be added for a given
index in the string. For ASCII strings that would be null. Then its size
grows with the number of multibyte characters. Beyond a threshold,
representation is transparently switched to utf16 or utf32 as needed and
the tree becomes smaller or null again.
Although I see some potential in a universal string type, I don't think
this is the right implementation strategy. I'd rather have my short
strings in utf-32 (optimized for speed) and my long strings in
utf-8/utf-16 (optimized for memory usage).
The definition I outlined does not specify or constrain the strategy of
changing the discriminator.
Andrei
