^\s*[)]*\s*$  

##</code><code>##

^\s*[(]*\s*$

##</code><code>##

    while
       (    #matches here
         (  #matches here
          (condition1) && (condition2) && 
           condition3 
        ) || 
        (#matches here
          (condition4) || 
           condition5 && 
           (condition6) 
         ) #matches here

      ) #matches here

##</code><code>##

    while
     (( #does not match here
          (condition1) && (condition2) && 
           condition3 
        ) || 
        (
          (condition4) || 
           condition5 && 
           (condition6) 
         ) ) #does not match here

##</code><code>##

    while
     ((( #does not match here
          (condition1) && (condition2) && 
           condition3 
        )) || 
        ((  #does not match here
          (condition4) || 
           condition5 && 
           (condition6) 
         ) ) ) #does not match here