Re: [Boost-users] [Intrusive] Obtaining end iterator from value reference

Subject: Re: [Boost-users] [Intrusive] Obtaining end iterator from value reference
From: Nat Linden (nat_at_[hidden])
Date: 2013-05-01 10:01:51

On Wed, May 1, 2013 at 7:09 AM, Ion Gaztañaga <igaztanaga_at_[hidden]> wrote:

> El 30/04/2013 3:00, Nat Goodspeed escribió:

>> On Apr 29, 2013, at 12:34 PM, Ion Gaztañaga <igaztanaga_at_[hidden]> wrote:

>>> There is no way to obtain the end node from a node in a circular list,
>>> as there is no runtime information stored in the ring that marks the end
>>> node.

>> But with a (non-empty) circular list, can't you just iterate until you
>> return to your starting point?

> The iterator does not know which node is the starting point (only the
> container stores a pointer to the first node). The iterator only stores a
> pointer to the next node, it does not know if the next node is the last or
> the first node as it's a circular slist.

I think the OP was talking about a function which is passed a single
node without knowing its location in the circular list.

I was suggesting that if the function can be sure it's a circular
list, it should still be possible to iterate over all items in the
list, if the function doesn't care whether it starts at the
container's official "first" node.