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From: David Abrahams (dave_at_[hidden])
Date: 2007-04-08 10:30:04

on Sat Apr 07 2007, "Ford, Rich" <> wrote:

> Thanks. I hadn't thought of that, but of course one could find the begin
> of the filtered sequence by constructing it from the begin of the base
> sequence. Then an algorithm doing decrementing could check to see if
> begin had been reached and avoid decrementing beyond that.

But what would the point be? An iterator, after decrementation, must
point at a valid element. If you're decrementing past the beginning
of the filtered sequence, there's no element (of the filtered
sequence) to stop on. Sure, I guess we could make decrementation a
no-op at the beginning of the sequence, but again, I don't see the

Dave Abrahams
Boost Consulting
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