Re: segmented fusion - a-ha!

Larry Evans wrote:
> On 05/26/2006 04:41 PM, Eric Niebler wrote:
> [snip]
>
> > Thanks, Dan. I've created a new branch called SEGMENTED_FUSION_V2. (It 
> > is a branch from FUSION_V2.) I will be adding segmented support to 
> > Fusion there, and periodically reverse integrating from FUSION_V2. When 
>
> Hi Eric.
>
> I've downloaded the SEGMENTED_FUSION_V2 and searched for anything with
> "segement" in the filename, but found nothing.  I also tried:
>
> cd ~/boost-cvs/ro/boost/sandbox/fusion/cvs/FUSION_V2/spirit/boost/
> find . -name \*.hpp -exec grep segment {} \; -ls
>
> with no results.


Right. I've created the branch, but haven't had time to make a check-in yet.


> I'm thinking of using these segmented iterators
> instead of what I'm currently using in http://tinyurl.com/pgoh4.
> The iterators corresponding to segmented iterators there are
> the ones with member functions first_non_empty and next_non_empty.
> I think my current implementation may be close to what Austern
> described as the inefficient seg_array_iter on p. 6 of the
> paper you cited earlier:
>
>   http://lafstern.org/matt/segmented.pdf
>
> in the boost-devel list.  Obvously I would like to use the
> more efficent one that you're developing.  Is there any
> chance you could upload the code so I could have a look
> and see if I could adapt it for my use.


The segmented iterators aren't particularly efficient if used with a 
non-segmented algorithm. Writing the segmented versions of all the 
Fusion algorithms is a ToDo item. Presently, I only have segmented 
versions of for_each and find_if.

You can find a recent version of the code (segmented_iterator<>, a 
segment-aware iterator_range<>, for_each and find_if) in the attachment 
at http://article.gmane.org/gmane.comp.parsers.spirit.devel/2781.

HTH,

--
Eric Niebler
Boost Consulting
www.boost-consulting.com


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