[chuck-users] object / class hacking

[Andrew C. Smith]

it would be

hashedList << element;

and you have to declare hashedList as hashedList[0] (not []) or else
you get a null pointer. For reference, it's in the release notes, and
I believe the examples (under examples/array/array_dynamic.ck or
something).

-Andrew

2009/9/30 Stefan Blixt <stefan.blixt at gmail.com>:
> More importantly, how do you get a nice hash key?
>
> You can iterator over contents on a simple array, store the keys there like:
>
> string hashKeys[];
>
> That's what you usually use to iterate over when doing hashmaps anyway (if
> you want to iterate over contents what do you need the hash for?)
>
> Here's a pseudocode attempt at a hashset (I keep forgetting the subtleties
> of @ and the autogrowing array syntax is missing from the annoying manual):
>
> class HashElement {
>     fun int hashCode();
> }
>
> class HashSet {
>     HashElement elements[][];
>
>     fun int contains(HashElement @ element) {
>         elements[element.hashCode()] @=> HashElement @ hashedList[];
>         for (0 => int i; i < hashedList.cap(); i++) {
>             if (hashedList[i] == element) {
>                 return 1;
>             }
>         }
>         return 0;
>     }
>
>     fun void insert(HashElement @ element) {
>         elements[element.hashCode()] @=> HashElement @ hashedList[];
>         if (hashedList == null) {
>             HashElement[1] @=> hashedList;
>             hashedList @=> elements[element.hashCode()];
>         }
>         element +=> hashedList[]; // keep forgetting the syntax for
> autogrowing the array
>     }
> }
>
> The elements you want to put in the hash set need to extend HashElement.
>
> /Stefan
>
> 2009/9/30 Robert Poor <rdpoor at gmail.com>
>>
>> Hans:
>> Of course I'd love to use a hashmap.  But how do you get one in Chuck?
>>  AFIK, the existing chuckain "hash array" lacks a means to iterate over its
>> contents.
>> - Rob
>> On 30 Sep 2009, at 02:03, Hans Aberg wrote:
>>
>> On 30 Sep 2009, at 02:13, Robert Poor wrote:
>>
>> I guess the question should be: what's the fastest way to maintain a *set*
>> of objects (i.e. a collection in which an object may only appear once) with
>> the usual operations for insertion, deletion and iteration?
>>
>> For lookup tables, if you do not need to compare the keys, a hash map is
>> fastest - time complexity O(1), otherwise a balanced tree (like C++
>> std::map) - complexity O(log n). There might be some C++ hash map classes at
>> <http://www.boost.org/>. But if n is small and use not too intense, just
>> about any container will do.
>>
>>  Hans
>>
>>
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>
>
>
> --
> Release me, insect, or I will destroy the Cosmos!
>
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