Joining Iterator Adaptor

From: rogeeff (rogeeff_at_[hidden])
Date: 2002-02-07 20:48:41

Hi,

I recently meet the need for joining iterator, i.e. iterator that 
traverse through "concatenation" of two collections; first elements 
of first collection then the second. Inducing example looked like 
this:

Let say we have a storage of objects that need to provide an access 
to them by integer ID. IDs could not constitute continuous set. But 
we can insure that tere is a continuous subset of most frequently 
accessed IDs. So storage implemented as combination of vector and map.
Now I need an iterator for this storage that will traverse through 
all the objects. Here where joining iterator come to use.

Implementation and test module are located here:

http://groups.yahoo.com/group/boost/files/Joining%20Iterator%
20Adaptor/

If boosters will find it intersting and reusable I could also provide 
example and docs.

There is one small flaw with current implementation: it could lie 
sometimes about resulting iterator category. Does anybody know 
elegant way to deduce most restrictive category of two provided?

Gennadiy.