[haiku-development] Re: BString method SymbolAt() proposal
- From: Ingo Weinhold <ingo_weinhold@xxxxxx>
- To: haiku-development@xxxxxxxxxxxxx
- Date: Sat, 19 Jun 2010 18:24:55 +0200
On 2010-06-19 at 14:18:21 [+0200], Reinhard Scharnagl <ReScharn@xxxxxxx>
wrote:
> Maybe I have been misunderstood. The routine should not cut the to be
found
> i-th symbol, but the symbol at index i.
>
> A routine part to invert a UTF8 string could look e.g. like:
>
> BString original = "Bärenstraße 1 - 200000 €";
> BString inverted, symbol;
> int len = original.Length;
> for (int i = 0; i < len; i += symbol.Length()) {
> symbol = original.SymbolAt(i);
> inverted.Prepend(symbol);
> }
That would work, but IMO the interface is not particularly nice. The
complexity is O(n), but due to returning a BString you get a memory
allocation and deallocation for each character, which is not really
efficient. Furthermore using a byte index into the string, but getting a
UTF-8 character is not exactly beautiful.
I would rather see a dedicated iteration interface for UTF-8 strings. E.e.
a very simple one in BUnicodeChar:
static const char* NextUT8Char(const char*& string,
size_t& _byteCount);
Could be used like:
BString reversed;
const char* cookie = original;
size_t byteCount;
while (const char* utf8Char = BUnicodeChar::NextUTF8Char(cookie,
byteCount)) {
reversed.Prepend(utf8Char, byteCount);
// BTW: O(n)!
}
A stateful iterator class, which would be even more convenient to use,
could be added as well.
On 2010-06-19 at 15:38:05 [+0200], Reinhard Scharnagl <ReScharn@xxxxxxx>
wrote:
[...]
> And I wonder how the current compiler will handle:
>
> wchar_t euro = '€';
>
> and simultaneously still support BString and multibyte message ids.
Wide char/string literals have the prefix "L" (i.e. L'a' or
L"Hello world!").
CU, Ingo
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