AA insertion order iteration

[Steven Schveighoffer]

On Mon, 14 Feb 2011 06:31:25 -0500, spir <denis.spir at gmail.com> wrote:

> Hello,
>
> How would you wrap an AA to allow memorising insertion order, and be  
> able to use it
> for iteration?
>
> * Indeed, one could store keys in a // (ordered) array. But this means
> iteration requires a series of lookups by key.
> * A slightly better method would be to store hash values, which anyway  
> are
> computed at insertion time, and pass them to whatever internal routine  
> is used to
> fetch an item.
> * Even better, store an array of pointers to the items.
>
> Typically, items in hash tables are kinds of cells in the "bucket"  
> storing
> pairs which "modulo-ed" hash values are equal. If I know the internal
> representation of such cells, then I can get (key,value) pairs. I've  
> read once
> such buckets are now linked lists, which can only make things simpler.
> The issue for last 2 solutions is I need to catch some info at insertion  
> time. The second one even requires calling an internal routine.
> Any chance? In any case, a pointer to current implementation of D AAs is  
> welcome.

Here is the main struct which calls the implementation functions:

https://github.com/D-Programming-Language/druntime/blob/master/src/object_.d#L2461

Hopefully the functions that it calls are clues as to where to find the  
implementations (all in druntime).  I warn you, they are based fully on  
runtime information, so they are going to be ugly.

-Steve