Keeping a dynamic sorted range

[Jakob Ovrum via Digitalmars-d]

On Friday, 7 November 2014 at 14:11:32 UTC, bearophile wrote:
> (This is a partial repost from a recent D.learn thread.)
>
> In Phobos we have SortedRange and assumeSorted, but I do find 
> them not very good for a common enough use case.
>
> The use case is to keep a sorted array, keep adding items to it 
> (adding larger and larger items at the end. Or sometimes even 
> inserting items in the middle. In both cases I keep the sorting 
> invariant). And while I add items, I also now and then want to 
> perform a binary search on the sorted range.
>
> So sometimes I'd like to do something like this (but a 
> SortedRange doesn't have append):
>
> struct Foo { int x; }
> SortedRange!(Foo[], q{ a.x < b.x }) data;
> data ~= Foo(5);
> immutable n = data.upperBound(Foo(2)).length;
>
> Bye,
> bearophile

Facing this same problem, a while ago I started work on a 
generic, higher-order container that provides insertion, deletion 
and search while keeping itself sorted:

https://gist.github.com/JakobOvrum/f1738d31bb7ba7a46581

The above is just a WIP; it's not complete. Of course, positional 
container primitives like `insertFront` and `insertBack` will not 
be supported.

The implementation is fairly messy due to the lack of traits for 
containers, as well as due to some deficiencies in `SortedRange`.

It's obviously useful for arrays, and it's kind of clever how it 
can merge lists efficiently, but I'm not sure if it's really 
worth all the effort; is it really useful to have something like 
this that aims to support such a wide range of underlying 
containers? Is it actually useful in real programs for anything 
but arrays? So, I stopped working on it...