input may not contain consecutive spaces.

Hi,

I'm currently looking for a way to place the following constraints on
input into one single regular expression:Maximum length = 35 characters,
input must consist of AlphaNumerics and &,_, [space],(,),,[comma],.,
input may not contain consecutive spaces.

The last constraint is driving me nuts and I'm not really sure if it's
possible to implement in one single regexp.
any help would be appriciated.

regards jeroen.