Re: [asio-users] New overload for async_read_until

[Christopher K. <ch...@ko...>]

Antti Tuppurainen wrote:
> Hello!
> I'm writing an irc bot (how cliché, eh?) for learning purposes, and 
> noticed that I could use a new overload for 
> boost::asio::async_read_until that takes a user-supplied predicate 
> functor, so I made one! I was originally using boost::regex("[\r\n]+") 
> for the delimiters to irc messages but since I'm not using regex 
> anywhere else in the program currently, it seemed a bit overkill to link 
> to the regex library just for that.
> 
> I'd like to submit this to boost::asio, it should be trivial to add and 
> provides imho very useful functionality. I have tested this code in my 
> application, though additional testing might be necessary in case I 
> didn't get all the details right.
> 
> Here's the code (added at the bottom of boost/asio/impl/read_until.ipp):
> http://www.anttirt.net/files/read_until_pred.txt 
> <http://www.anttirt.net/files/read_until_pred.txt>

Yep, this is almost what I'd like to add, however... the one problem 
with your current solution is that it relies on the position() function 
implemented by asio::detail::const_buffers_iterator. As a result the 
predicate is tied to this implementation detail and can't be used with 
other bidirectional iterators.

I think perhaps I should create some buffers_iterator types that are 
part of the asio public interface. These should be random access 
iterators (rather than bidirectional) so that one can be subtracted from 
the other to obtain the position, a position can be added to a "begin" 
iterator, etc. I'll have a think about whether this can be implemented 
cleanly and efficiently.

Cheers,
Chris