is there an implementation of a set in PHP?

jazz_snob

<warning>I am new to PHP</warning>. I'm interested in having a class called Set which, basically, is a glorified array which never contains duplicate values. This is either (1) a bad idea or (2) ground breaking ( probably (1) ) because I've googled and fumbled through PHP and PEAR and didn't find any off-the-shelf stuff for a Set. Is there such a thing in existance? I've already started the class and it supports add(), remove(), size(), is_empty() and contains().

Is there an implementation of Set already in PHP? Am I completely nuts? 😕

Check out my source if you're interested at http://www.flat5software.com/dev/set.html and there is a link to my simpletest unit test too.

TheBB

Personally I like the idea. I haven't found any use for set types so far in PHP, but I use them frequently in Delphi, and I can see me having use for it in the future.

MarkR

You can use the keys of an associative array to model a set. Or even write yourself a set class:


class Set {
   var $contents;
   function Set() { $this->contents = array(); }
   function Add($value) { $this->contents[$value] = true; }
   function Contains($value) { return (bool) @ $this->contents[$value]; }
   function Remove($value) { delete $this->contents[$value]; }
}

Something like that.

Above is untested and probably syntactically correct, but you get the gist. Implementations of union, intersection, difference, symmetric difference, isempty, count, are left as exercises for the reader 🙂

Mark

drawmack

actually this would be easy to implement with the in_array function. However becareful with case sensitivity. I would force all entries to upper or lower case, whichever you prefer, then whenever I was getting a value from the user I would convert the input to this case so that the class is case insensitive. Or at least make a switch for case sensitivity.