Re: foreach for string[string]AA

[Anton Pastukhov via Digitalmars-d-learn]

On Wednesday, 1 March 2017 at 19:26:23 UTC, Mike Wey wrote:

On 02/28/2017 07:16 PM, Anton Pastukhov wrote:
On Tuesday, 28 February 2017 at 17:16:43 UTC, Daniel Kozák 
wrote:

[...]


Thank you for the link, it was informative reading. It's a 
pity that

still there is no ordered AA at least as a library type.


I had the same use case in the generator for GtkD, i needed 
fast lookup while iteration needed to preserve the insertion 
order. I opted for storing nodes of a linked list in the build 
in AA.


The implementation[1] is currently LGPL to match the rest of 
the library, but if anyone would find it useful it can be 
changed to something else.


[1] 
https://github.com/gtkd-developers/GtkD/blob/master/wrap/utils/LinkedHasMap.d


Interesting.
How this approach is compared to array of tuples performance-wise?

Re: foreach for string[string]AA

[Anton Pastukhov via Digitalmars-d-learn]

On Tuesday, 28 February 2017 at 17:16:43 UTC, Daniel Kozák wrote:

V Tue, 28 Feb 2017 15:15:00 +
Anton Pastukhov via Digitalmars-d-learn
<digitalmars-d-learn@puremagic.com> napsáno:


I can't see the logic in AA foreach order. Consider this code:
...
Output:
three
two
one
four

I was sure output should be
one
two
three
four


https://forum.dlang.org/post/xbanhtkvrizyqjcib...@forum.dlang.org


Thank you for the link, it was informative reading. It's a pity 
that still there is no ordered AA at least as a library type.

Re: foreach for string[string]AA

[Anton Pastukhov via Digitalmars-d-learn]

On Tuesday, 28 February 2017 at 15:44:46 UTC, bachmeier wrote:

On Tuesday, 28 February 2017 at 15:33:46 UTC, ikod wrote:

AA implemented as hash table, so it doesn't preserve insertion 
order. You have to sort keys when you need:


import std.algorithm;
import std.stdio;
void main() {
auto aa = ["one":1,
   "two":2
   ];
foreach(k; sort(aa.keys)) {
writeln(k);
}
}


That will only work if sorting recovers the insertion order. An 
easy way to save the insertion order would be to use an array 
of structs. If an associate array is really needed, you can 
create a struct that contains the associative array and a 
string[] holding the keys.


Thank you for quick replies. I'm used to arrays in PHP that are 
actually ordered maps, so I was expected the same from D's AAs. 
For now I'm fine with array of structs.

foreach for string[string]AA

[Anton Pastukhov via Digitalmars-d-learn]

I can't see the logic in AA foreach order. Consider this code:

```
void main() {
string[string] test = [
"one": "1",
"two": "2",
"three": "3",
"four": "4"
];

import std.stdio:writeln;

foreach(k, v; test) {
writeln(k);
}
}

Output:
three
two
one
four

I was sure output should be
one
two
three
four