Daniel Mitchell wrote:
On Thursday 06 July 2006 11:17, Robert Ramey wrote:
typedef boost::archive::iterators::insert_linebreaks< boost::archive::iterators::base64_from_binary< boost::archive::iterators::transform_width< const char *, 6, 8
,72 ,const char // cwpro8 needs this
base64_text;
Wow - just great. Now just construct an instance of base64_text - and we're in business. So I can do:
char * address; // pointer to character buffer ... boost::archive::iterators::ostream_iterator<char> oi(os); std::copy( base64_text(address), base64_text( address + count ), oi );
So the advantage is the ability to construct a base64_text iterator directly from a char const* without manually constructing each of the underlying iterator adaptor layers. That's neat, but wouldn't a function
Yes - the newly created iterator - created with the typedef - hides all the underlying implementation just presents the "composed" interface.
base64_text make_base64_text_iterator( char const* );
work just as well?
How would I make such a function automatically? wouldn't have to do something like base64_text make_base64_text_iterator( make_insert_linebreaks<...>( make_transform_width<...>(char const *) ) ) and not a LOT of stuff goes in to the ... But maybe it could be made to work. I just much preferred the idea of not having extra make_??? functions. The method I used lets me make a "stable" of iterators and compose them at will. The generated iterators (derived from boost iterator adaptor) are all (I think) legal iterators and can be used in any STL algorithms. It comes close to implementing what people are a talking about now. And it does all te heavy lifting at compile time so that the the compiler can inline everything. What I would like to see is a code_cvt facet which used an iterator as template argument. Combined with the above I could easily generate any code_cvt facet from my "stable" of composible iterators. This could be attached to any output stream to do stuff like base64 output or utf8 output or whatever. Note that the serialization library uses this to implment things like mb_from_wchar etc. so I would expect it would be easy to make things like utf8_from_mb. and add this to the "stable" of dataflow iterators. Robert Ramey