[Boost-users] any boost iterator adapter to make it java style iterator ?

From: abir basak (abirbasak_at_[hidden])
Date: 2007-03-02 09:08:41

Hi,
   In some case I need a iterator which knows its position (index ) in 
the container, so that I can get the index back from iterator.
The need is two fold.
1) This is needed for simultaneous traversal to different container.
  i.e i have vector<point> and vector<velocity> where each point 
corresponds to velocity at same position. Thus converting the iterator 
to the index helps.
   But even better if I have a multi iterator, which can club a set of 
iterators, and allow to return all of them (like (*it).point() returns 
point, (*it).velocity() returns velocity etc. Also it defines ++, -- etc 
the same way (i.e increments all these, or one in a logic , say next 
point is a jump in velocity by 2 etc), so that I can use 
boost::sub_range for these kind of iterator.

2) I need to convert iterator to index, as I need to store certain 
portion of a container (which changes its size) in a class. There I can 
only store index as iterator may get invalidated.
It is something like,
   void mark_if_useful(point_sub_range r){///an portion of the container
      point_iterator it = r.begin();
      for(; it != r.end() ; ++it){
       if ((*it).x == 123 ) {
           ///ok certain criterion is fulfilled
           ///I need to mark (ans store tis position)
           ///I can't store *it as it is a pointer to a movable object
           ///However I can store (*it).index() may be it is 5th 
location                in the vector, and (*it)>container() also the 
reference to the container
///may not be needed if the container is globally available.
///if some object also gets removed the the remove count from the 
container can be added to have a unique linear index (that can me done 
adding additional method to the container :) )
       }
      }
   }

-- 
Abir Basak, Member IEEE
Software Engineer, Read Ink Technologies
B. Tech, IIT Kharagpur
email: abir_at_[hidden]
homepage: www.abirbasak.com