shorten/compress mod_rewrite rules - .htaccess

Question

amongst my rules i have..
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/\.]+)/([^/\.]+)/([^/\.]+)/([^/\.]+)/?$ index.php?page=$1&submenu=$2&info=$3&id=$4 [QSA,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/\.]+)/([^/\.]+)/([^/\.]+)/?$ index.php?page=$1&submenu=$2&info=$3 [QSA,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/\.]+)/([^/\.]+)/?$ index.php?page=$1&submenu=$2 [QSA,L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^([^/\.]+)/?$ index.php?page=$1 [QSA,L]
Which seems a little bulky to me and repeats a lot of stuff, any ideas on how i can shorten it?
Can i set "global" conditions?
Can i have one rule like this that captures all the ones below it (i dont care if it sends through empty varibles)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule **clever stuff here** index.php?page=$1&submenu=$2&info=$3&id=$4 [QSA,L]
So it would capture
domain.com/a/b/c/d
and
domain.com/a/b/c
and
domain.com/a/b
and
domain.com/a
Answers, Thoughts, Musings, and Existential Arguments all appreciated...

Answer 1

You can pretty easily remove the conditions if you check for the inverse and let it pass through the rewrite engine. Then anything afterwards you know isn't an existing file or directory:
RewriteCond %{REQUEST_FILENAME} -f [OR]
RewriteCond %{REQUEST_FILENAME} -d
RewriteRule ^ - [L]
RewriteRule ^([^/\.]+)/([^/\.]+)/([^/\.]+)/([^/\.]+)/?$ index.php?page=$1&submenu=$2&info=$3&id=$4 [QSA,L]
RewriteRule ^([^/\.]+)/([^/\.]+)/([^/\.]+)/?$ index.php?page=$1&submenu=$2&info=$3 [QSA,L]
RewriteRule ^([^/\.]+)/([^/\.]+)/?$ index.php?page=$1&submenu=$2 [QSA,L]
RewriteRule ^([^/\.]+)/?$ index.php?page=$1 [QSA,L]
It's not a fancy multiple-look-ahead regex that does it all in one line, but it does make it easier to read.
EDIT:
Well, like I said, you do it with multiple look-aheads, something like:
RewriteRule ^(?:([^/.]+)|)(?:/([^/.]+)|)(?:/([^/.]+)|)(?:/([^/.]+)|) index.php?page=$1&submenu=$2&info=$3&id=$4 [QSA,L]
But it's harder to read, and more likely to do something unexpected if you change something. Additionally, whereas having explicit 4 different mappings, you don't get blank query string params like you do with look-aheads. Whether the last (?:/([^/.]+)|) is there or not, you will still get an id param (just blank).