Re: [boost] Comment on string / unicode discussion

From: Joel de Guzman (joel_at_[hidden])
Date: 2006-07-06 01:05:09

Sean Parent wrote:
>> This is very close to what I have in mind. The main difference is that
>> the functions/algorithms in my mind take ranges instead of iterators.
>> Thus:
>>
>>      to_lower(src, dest)
>>      to_upper(src, dest)
> So long as you don't require ranges (or a pair of iterators makes a  
> valid range and dest can still be an output iterator). That's fine -  
> these should work on char* as well as container types. I don't know  
> what kind of ranges you have for dest which allow dest to change size  
> - seems a bit problematic.

Yeah. A bit problematic. This is not a problem with the pure functional
approach where you return a lazily evaluated view:

     to_lower(src) // returns a view

> I want iterators that can handle the encoding transform. I want to be  
> able to write items like the following:
> 
> std::string s = get_some_utf_8_xml_data();
> 
> // Find the BOM character as a UTF-32 character
> 
> utf_iterator_t i = std::find(utf_iterator_t(s.begin()), utf_iterator_t 
> (s.end()), UL0x0000FEFF);
> 
> assert(*i.base() == U0xEF); // base iterator points to start of UTF-8  
> character

Contrast that with:

     std::string s = get_some_utf_8_xml_data();

     utf_range r = boost::find(utf_range(s), UL0x0000FEFF);

     assert(*r.begin().base() == U0xEF);

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net