Actually the code can be further optimized:
Dictionary>>keys
"Answer a Set containing the receiver's keys."
| result container |
result := Set basicNew setTally: tally array: array copy.
container := result array.
1 to: container size do: [ :index |
(container at: index)
ifNotNil: [ :assoc | container at: index put: assoc key
] ].
^ result
This is roughly 22 times faster than the current implementation, and 5
times faster than the squeak implementation.
The system doesn't seem to break with this change :-)
Lukas
2009/12/4 Lukas Renggli <[email protected]>:
> I wonder if ever something along the following lines was considered?
>
> Dictionary>>keys
> "Answer a Set containing the receiver's keys."
>
> | result |
> result := Set basicNew.
> result setTally: tally array: (array collect: [ :each |
> each isNil ifFalse: [ each key ] ]).
> ^ result
>
> This returns a Set, so it wouldn't break any semantics. In my
> benchmark this is roughly 8x faster than the current implementation,
> and 2x faster than the optimized Squeak implementation.
>
> The drawback is that it makes some heavy assumptions on the internal
> structure of Dictionary, Association and Set.
>
> Lukas
>
> 2009/12/4 Henrik Sperre Johansen <[email protected]>:
>> A small addendum ;)
>> On 03.12.2009 22:13, Nicolas Cellier wrote:
>>> 3) identify thise sending a potential inefficient message (includes:)
>>> insert keys asSet in this case (only if includes: is in a loop!)
>>>
>>>
>> 3b. If the keys collection isn't used for anything else, change to use
>> includesKey: instead.
>>
>> Cheers,
>> Henry
>>
>> _______________________________________________
>> Pharo-project mailing list
>> [email protected]
>> http://lists.gforge.inria.fr/cgi-bin/mailman/listinfo/pharo-project
>>
>
>
>
> --
> Lukas Renggli
> http://www.lukas-renggli.ch
>
--
Lukas Renggli
http://www.lukas-renggli.ch
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