[boost] Re: SkippingIterator (Was: live_ptr => live_container / live_iterator)

From: Valentin Bonnard (Bonnard.V_at_[hidden])
Date: 1999-08-17 12:09:40

Greg Colvin wrote:
> 
> From: Valentin Bonnard <Bonnard.V_at_[hidden]>
> > A priori, writing a skiping iterator seems trivial:
> >
> > template <typename It, typename Predicate>
> > class SkippingIterator {
> >     mutable It pos;
> >     Predicate pred;
> >
> >     void skip () const
> >     { while (pred (*pos)) ++pos; }
> >
> > public:
> >     value_type& operator* () const
> >     { skip (); return *pos; }
> >
> >     void operator++ ()
> >     { skip(); ++pos; }
> > };
> >
> > Except that the semantic near the end is ugly (the precondition
> > is that there are non skipped elements before the end).
> 
> I think the precondition is just that pred(*last) is false.

Saying pred(*x) is false is saying that x is non skipped.

We are saying the same thing.

This precondition is ugly (why would the elements 
at some position be skippable and not the others ?)

-- 
Valentin Bonnard