I have a few questions about the pseudo built in associative arrays.

1. Is it possible to have the built in associative array use a custom allocator from std.experimental.allocator to service it's allocation needs?

2. A while ago I read on the newsgroup a while back that there was a plan to make it possible for a user to swap out the standard associative array implementation by modifying druntime and or implementing some linker functions. Have this been done yet? And if so what must I do to swap the implementation?

On 09/11/15 4:57 PM, TheFlyingFiddle wrote:
> I have a few questions about the pseudo built in associative arrays.
>
> 1. Is it possible to have the built in associative array use a custom
> allocator from std.experimental.allocator to service it's allocation needs?

Nope.

> 2. A while ago I read on the newsgroup a while back that there was a
> plan to make it possible for a user to swap out the standard associative
> array implementation by modifying druntime and or implementing some
> linker functions. Have this been done yet? And if so what must I do to
> swap the implementation?

As far as I'm aware, you are stuck using e.g. structs to emulate AA behavior.
I have a VERY basic implementation here: https://github.com/rikkimax/alphaPhobos/blob/master/source/std/experimental/internal/containers/map.d
Feel free to steal.

On Monday, 9 November 2015 at 04:29:30 UTC, Rikki Cattermole wrote:
> On 09/11/15 4:57 PM, TheFlyingFiddle wrote:
>> [...]
>
> Nope.
>
>> [...]
>
> As far as I'm aware, you are stuck using e.g. structs to emulate AA behavior.
> I have a VERY basic implementation here: https://github.com/rikkimax/alphaPhobos/blob/master/source/std/experimental/internal/containers/map.d
> Feel free to steal.

Fwiw, EMSI provides high quality containers backed by std.experimental.allocator.
https://github.com/economicmodeling/containers

On Monday, 9 November 2015 at 04:52:37 UTC, rsw0x wrote:
> On Monday, 9 November 2015 at 04:29:30 UTC, Rikki Cattermole wrote:
>> On 09/11/15 4:57 PM, TheFlyingFiddle wrote:
>>> [...]
>>
>> Nope.
>>
>>> [...]
>>
>> As far as I'm aware, you are stuck using e.g. structs to emulate AA behavior.
>> I have a VERY basic implementation here: https://github.com/rikkimax/alphaPhobos/blob/master/source/std/experimental/internal/containers/map.d
>> Feel free to steal.
>
> Fwiw, EMSI provides high quality containers backed by std.experimental.allocator.
> https://github.com/economicmodeling/containers

Thanks for the suggestions. I also made a hashmap using allocators some time ago that I use in-place of the built in hashmap for most of my purposes. The syntax of a custom hash map is somewhat lacking in comparison to the built in one however and I was hoping that I could either make the built in work with allocators or replace it with my own implementation.

In addition to this I am building a pointer patching binary serializer and I hoped that I could make it work with the built in aa without requiring to many gc allocations.

The economicmodeling one seems interesting ill try it out and see if it's better then the one I am currently using.

On Monday, 9 November 2015 at 04:52:37 UTC, rsw0x wrote:
> On Monday, 9 November 2015 at 04:29:30 UTC, Rikki Cattermole wrote:
> Fwiw, EMSI provides high quality containers backed by std.experimental.allocator.
> https://github.com/economicmodeling/containers

I have a question regarding the implementation of the economicmodeling hashmap. Why must buckets be a power of two? Is it to be able to use the: hash & (buckets.length - 1) for index calculations or is there some other reason?

On Monday, 9 November 2015 at 21:33:09 UTC, TheFlyingFiddle wrote:
> On Monday, 9 November 2015 at 04:52:37 UTC, rsw0x wrote:
>> On Monday, 9 November 2015 at 04:29:30 UTC, Rikki Cattermole wrote:
>> Fwiw, EMSI provides high quality containers backed by std.experimental.allocator.
>> https://github.com/economicmodeling/containers
>
> I have a question regarding the implementation of the economicmodeling hashmap. Why must buckets be a power of two? Is it to be able to use the: hash & (buckets.length - 1) for index calculations or is there some other reason?

I have no idea, sorry.
Schott wrote them AFAIK, he might be able to respond if he sees this.

On Monday, 9 November 2015 at 21:33:09 UTC, TheFlyingFiddle wrote:
> On Monday, 9 November 2015 at 04:52:37 UTC, rsw0x wrote:
>> On Monday, 9 November 2015 at 04:29:30 UTC, Rikki Cattermole wrote:
>> Fwiw, EMSI provides high quality containers backed by std.experimental.allocator.
>> https://github.com/economicmodeling/containers
>
> I have a question regarding the implementation of the economicmodeling hashmap. Why must buckets be a power of two? Is it to be able to use the: hash & (buckets.length - 1) for index calculations or is there some other reason?

Yes. It's a hack that gives you a modulus without having to do a modulus. It only works on powers of two.

On Tuesday, 10 November 2015 at 01:29:11 UTC, Brian Schott wrote:
> Yes. It's a hack that gives you a modulus without having to do a modulus. It only works on powers of two.

http://graphics.stanford.edu/~seander/bithacks.html#ModulusDivisionEasy