function str = procshuffnot(str)

while 1
  i = find(str=='~');
  if isempty(i)
    return
  end
  str1 = str(i+1:end);
  [X,rest]=peeloff(str1);
  str1 = '~($)';
  str2 = '((@)-($))';
  str1 = strrep(str1,'$',X);
  str2 = strrep(str2,'$',X);
  str = strrep(str,str1,str2);
end

return


function [chunk,rest]=peeloff(str)
str = [str,'()'];
x=find(str=='(');
if (x(1)>1)
  % we can peel off a char
  chunk = str(1);
  rest = str(2:end); % keep that open paren
else
  % it starts with a paren
  cnt=0; t=1; done=0;
  while ~done
    if (str(t)==')')
      cnt=cnt-1;
    elseif (str(t)=='(')
      cnt=cnt+1;
    end
    t=t+1;
    done = (~cnt+(t>length(str)));
  end
  if cnt
    error('unmatched parentheses in regexp');
  end
  chunk = str(2:t-2);
  rest = str(t:end);
end
rest = rest(1:end-2);
return