private boolean push(byte mode){
  ++top;
  if (top >= stack.length) {
    if (top >= depth) {
      return false;
    }
    stack=Arrays.copyOf(stack,Math.min(stack.length * 2,depth));
  }
  stack[top]=mode;
  return true;
}

private boolean push ( byte mode ) { ++ top ; if ( top >= stack . length ) { if ( top >= depth ) { return false ; } stack = Arrays . copyOf ( stack , Math . min ( stack . length * 2 , depth ) ) ; } stack [ top ] = mode ; return true ; }
push a mode onto the stack
