custom sorting of lists ?

[Steven Schveighoffer]

On 10/12/18 3:40 PM, Codifies wrote:
> a while ago I wrote a doubly linked list (in C), which has a compare 
> callback to allow custom sorting for example
> 
> int cmpNodes(cnode_t* n1, cnode_t* n2)
> {
>    mapNode_t* rn1 = (mapNode_t*)(n1->data);
>    mapNode_t* rn2 = (mapNode_t*)(n2->data);
>    if (rn1->G + rn1->H > rn2->G + rn2->H) return 1;
>    return 0;
> }
> 
> would be called by
> 
> clistSort(openList, cmpNodes);
> 
> The list would then be ordered by G + H fields (or any other algorithm 
> you code)
> 
> 
> I notice there is a doubly linked list in the standard library, however 
> it doesn't seem to allow for a custom compare, I'd rather not port my 
> old C list code, can someone please give me some clues as to how I can 
> reorder a list with a custom comparison...?

Unfortunately, I can't find a way to sort a doubly linked list in 
phobos, so comparisons are somewhat moot.

However, if there *were* a sorting routine, generally the comparison 
function is done via whatever type you give it, or is given a custom 
comparison routine.

In my ancient dcollections library linked-list sorting is supported via 
a `less` parameter: 
https://github.com/schveiguy/dcollections/blob/82118cfd4faf3f1ad77df078d279f1b964f274e7/dcollections/LinkList.d#L997

-Steve