Lists Allowing for Switching Values

[Francesco Cattoglio]

On Monday, 10 February 2014 at 19:35:55 UTC, Jeroen Bollen wrote:
> Is there a way in D to have a list that allows you to shift 
> around values? I'm creating a cache and I would like to keep a 
> log of when an item was last accessed so when the cache shrinks 
> or is about to overflow I can delete the items that haven't 
> been accessed in a while.
>
> I would like to be able to push to the back and pop from the 
> front. Do note that I would like to pop from the front, and not 
> from the back, as I want the oldest items to be popped out.
>
> I would like the be able to search if the item is actually in 
> the list. If no such functionality exists yet I could 
> alternatively implement it myself; it's not crucial.
>
> I would like to be able to switch items around. This allows me 
> when an item already in the list is accessed, I can put it back 
> at the back, where the most recent items reside.
>
> Does such a feature exist already in D, is there perhaps a 
> better approach about doing this?

It all depends on the access times you need.
If you are fine with O(n) or O(log n), then something from 
std.container with a few extra helper functions will do just fine.
O(1) on the other hand, might require 2 associative arrays you 
will have to keep it sync. Nothing impossible anyway.