• Etienne Cimon (5/5) Feb 22 2014 Would it eventually be in the making for D to have associative arrays
• Max Klyga (4/11) Feb 22 2014 Wanted to recomend using tuples, but it seems TypeInfo.compare is not
• H. S. Teoh (14/19) Feb 22 2014 [...]
• Etienne Cimon (11/13) Feb 22 2014 I thought of that but it's not immediately obvious how I could achieve
• Vladimir Panteleev (8/13) Feb 23 2014 You can't sort an AA, as AAs are unordered. Did you mean to sort
• Andrei Alexandrescu (8/21) Feb 23 2014 The way multiple binary tree (or rb-tree) indexes are achieved is by

Etienne Cimon <etcimon gmail.com> writes:

Would it eventually be in the making for D to have associative arrays 
like string[string, int, Item]?

If it hasn't been planned, I'd say it would be great to have an API that 
allows it to carry functionality of Boost Multi Index

Thoughts?

Max Klyga <max.klyga gmail.com> writes:

On 2014-02-23 03:10:23 +0000, Etienne Cimon said:

 Would it eventually be in the making for D to have associative arrays 
 like string[string, int, Item]?
 
 If it hasn't been planned, I'd say it would be great to have an API 
 that allows it to carry functionality of Boost Multi Index
 
 Thoughts?

Wanted to recomend using tuples, but it seems TypeInfo.compare is not 
implemented for tuples.
Not sure it its a bug or is it fixed in current compiler versions.

"H. S. Teoh" <hsteoh quickfur.ath.cx> writes:

On Sat, Feb 22, 2014 at 10:10:23PM -0500, Etienne Cimon wrote:
 Would it eventually be in the making for D to have associative
 arrays like string[string, int, Item]?
 
 If it hasn't been planned, I'd say it would be great to have an API
 that allows it to carry functionality of Boost Multi Index

[...]

You can just use a struct or tuple as the AA key to achieve the same
thing.

	struct Key {
		string x;
		int y;
		Item z;
	}

	string[Key] aa;
	aa[Key("a", 1, Item(...))] = "b";


T

-- 
Some days you win; most days you lose.

Etienne Cimon <etcimon gmail.com> writes:

On 2014-02-23 01:27, H. S. Teoh wrote:
 You can just use a struct or tuple as the AA key to achieve the same
 thing.

I thought of that but it's not immediately obvious how I could achieve 
sorting or filtering by a certain field

e.g.
auto sorted = aa.sort!(Key.y => { a < b })
auto filtered = aa.filter! ....

foreach(x, y, z ; aa){
....
}

I don't see a very simple way of doing this right now. I'm sure someone 
thought of a library for this?

"Vladimir Panteleev" <vladimir thecybershadow.net> writes:

On Sunday, 23 February 2014 at 07:10:32 UTC, Etienne Cimon wrote:
 auto sorted = aa.sort!(Key.y => { a < b })

You can't sort an AA, as AAs are unordered. Did you mean to sort 
the keys?

auto sorted = aa.keys.sort!((a, b) => a.y < b.y)();

 auto filtered = aa.filter! ....

auto filtered = aa.keys.filter!(k => k.y > 2).array;

 foreach(x, y, z ; aa){
 ....
 }

foreach (key, value; aa) with(key) {
   ... use x, y, z ...
}

Andrei Alexandrescu <SeeWebsiteForEmail erdani.org> writes:

On 2/22/14, 11:10 PM, Etienne Cimon wrote:
 On 2014-02-23 01:27, H. S. Teoh wrote:
 You can just use a struct or tuple as the AA key to achieve the same
 thing.

 I thought of that but it's not immediately obvious how I could achieve
 sorting or filtering by a certain field

 e.g.
 auto sorted = aa.sort!(Key.y => { a < b })
 auto filtered = aa.filter! ....

 foreach(x, y, z ; aa){
 ....
 }

 I don't see a very simple way of doing this right now. I'm sure someone
 thought of a library for this?

The way multiple binary tree (or rb-tree) indexes are achieved is by 
storing multiple pointers with the same value. That way really multiple 
threes are threaded using the same value nodes.

There's no trivial way to do this. It would be very valuable to 
generalize RBTree to accept multiple predicates and build such multiple 
indexes.


Andrei