Re: [Boost-users] [mpl] Collapsing sequences of integer constants

From: David Abrahams (dave_at_[hidden])
Date: 2006-07-29 00:50:38

"Eric Lemings" <lemings_at_[hidden]> writes:

> Greetings,
>  
> I'm trying to come up with an algorithm that will "collapse" a sequence
> of integer constants by adding like elements together.  For example,
>  
>     typedef vector_c< int, 1,1,1,3,5,5,7,10,10 > input;
>  
> would become:
>  
>     typedef vector_c< int, 3, 3, 10, 7, 20 > result;
>  
> You can assume the sequence is already sorted.  Would appreciate any
> tips.

You could use mpl::fold with a "state" that consists of a pair
containing the (partial) new sequence and the last element of the
input sequence processed so far.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com