[chuck-users] object / class hacking

[Stefan Blixt]

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
>
>
>
> _______________________________________________
> chuck-users mailing list
> chuck-users at lists.cs.princeton.edu
> https://lists.cs.princeton.edu/mailman/listinfo/chuck-users
>
>


-- 
Release me, insect, or I will destroy the Cosmos!
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.cs.princeton.edu/pipermail/chuck-users/attachments/20090930/02d904a3/attachment.html>