Re: [boost] challenge: stable_vector

From: Ullrich Koethe (u.koethe_at_[hidden])
Date: 2001-07-11 14:36:00

Jeremy Siek wrote:
> 
> Yes, iterator stability would be problematic.
> 

I think, a stable iterator for a sorted vecor could be achieved by means
of an 'is_dirty()' function, sililar to a cache. ("stable" in the sense
that it always points to the same element. Stable
successors/predecessors cannot be guaranteed.):

/* untested code */
template <class SortedVector>
class sorted_vector_iterator
{
    SortedVector & its_vector;
    typename SortedVector::key_type its_key;
    typename SortedVector::value_type * its_element;
    typedef typename SortedVector::value_type value_type;

    void update()
    {
        if(its_vector.is_dirty())
        {
            its_element = &its_vector[its_key]; // or similar
        }        
    }

    sorted_vector_iterator & operator++()
    {
        update();
        its_element++;  // or similar
        return *this;
    }

    value_type operator*()
    {
        update();
        return *its_element;
    }
};

Am I missing something?

Ulli
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