code: @Override
      public int compareTo(ParserAction other) {
  	int result = this.action.compareTo(other.action);
  	if (result != 0) {
  	    return result;
  	}
  	return other.parameter - this.parameter;
      }
docs: This comparison is used to sort parser action lists for ambiguous
  grammars to get the order of fastest progress.
  
  The experience tells that the fastest progress is to shift first and try
  to reduce later. And the sorting of the productions within the grammar
  file should be from rough to fine definition and the reduction is tried
  from the latest production to the first. Means, from fine to rough.