BUG: Static variables in "PCN. CPP" cause an bug

The static variable "preList" of lines 134 and 577 in "PCN. CPP" will cause the trace results to be inconsistent when two copies of the same data are executed sequentially.I recommend changing to a member variable in the "Impl" class.
(chinese:在“PCN.cpp"中134行与577行的静态变量"preList"会导致顺序执行两份相同数据时给出的跟踪结果不一致。建议改成"Impl"类中的成员变量。）