From: Harpo <trashcan@...>
Date: 2005-12-08T05:42:35+09:00
Subject: Re: Build array of possible combinations

Timo Hoepfner wrote:

> Hi,
> 
> I'm looking for an easy way to convert a string representing a
> boolean expression like
> 
> "(a and (b or c) or d"

Unpaired parentheses ! (I was a compiler in a previous life, I just
can't help ;))

> 
> to an Array of Arrays (representing sets) representing all possible
> valid combinations like:
> 
> [["a","b"],["a","c"],["d"]]

The question is interesting, my answer is probably a bad hack.
Say you use a regular expression to transform the string in
"exp([a.xand([b,c]),d])
Maybe it is possible. I think it is.
It seems to be a well formed Ruby expression and can be parsed by Ruby
using eval, you just have to write the xand mathod ('and' is likely to
be a reserved word in a language) end the exp method, maybe the same as
xand.
This methods can build the array you need.

Well, It is just a direction.
I thank you for this problem.
--
email : jigmepema <at> wanadoo <dot> fr