Re: [boost] [range] new adaptor for iterating over equal_ranges

Subject: Re: [boost] [range] new adaptor for iterating over equal_ranges
From: Mathias Gaunard (mathias.gaunard_at_[hidden])
Date: 2010-04-23 08:23:49

Thorsten Ottosen wrote:
> Hi Neil & others,
> 
> I think it could be useful with a range adaptor of the following kind to
> iterate over equal_ranges in a multimap. E.g.
> 
>   SomeMultiMap map = ...;
>   for( auto rng : map | boost::adaptors::equal_ranged )
>      for( auto iter : rng )
>      {
>        // do something with the objects with equal keys
>      }
> 
> The resulting range would probably be bidirectional with value_type 
> std::pair<boost::range_iterator<SomeMultiMap>::type,...>.

That would be trivial to do with boost::consumer_iterator (which is 
being renamed to boost::segment_iterator) that is part of my Unicode 
library.
The value type is boost::sub_range<SomeMultiMap>.

I would quite like my iterator/range adaptors developed for Unicode to 
be included into iterator/range at some point, but I've had little 
feedback on them.
I've got:
  * join_iterator, that lazily concatenates a tuple of ranges into a 
single range,
  * segment_iterator, that adapts a range as a range of subranges with a 
lazily evaluated segmentation criterion,
  * convert_iterator, that lazily converts N to M elements in a range.

All three are bidirectional (I suppose join_iterator could maybe be 
more, but that's not supported)