Mod_Rewrite / Regex to PHP URL

I am new to using mod_rewrite and am trying to rewrite a URL to pass
values to my script so that:
>
http://www.myclient.com/everything/animals/mammals/cats
>
is transformed into
>
http://www.myclient.com/index.php?nav[0]=everything&nav[1]=animals&nav[2]=mammals@nav[3]=cats
>
Specifically, I am looking for an n-ary solution to this problem. I know
how to do it for a discrete number, but how do I do this transformation
when the number of variables to go into the nav array is unknown, and
how do I generate the index number? Can any experience mod_rewrite gurus
point me in the right direction. I'm sure this is a common design
pattern.

>I am new to using mod_rewrite and am trying to rewrite a URL to pass values
>to my script so that:
>
http://www.myclient.com/everything/animals/mammals/cats
>
is transformed into
>
http://www.myclient.com/index.php?nav[0]=everything&nav[1]=animals&nav[2]=mammals@nav[3]=cats
>
Specifically, I am looking for an n-ary solution to this problem. I know
how to do it for a discrete number, but how do I do this transformation
when the number of variables to go into the nav array is unknown, and how
do I generate the index number? Can any experience mod_rewrite gurus point
me in the right direction. I'm sure this is a common design pattern.

As you're using PHP, what's wrong with:
>
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php?nav=$1
>
And in PHP:
>
$nav = isset($_GET['nav']) ? explode('/',$_GET['nav']) : array();