#include "Elevator.h"
#include <iostream>
#include<iomanip>
using namespace std;

Queue::Queue() {
	//构造一个空队列
	this->front = this->rear = new PassengerList();
	this->QueueLength = 0;
}

int Queue::InitQueue() {
	//初始化队列
	this->front = this->rear = new PassengerList;
	if (!this->front)
		return -1;//分配存储失败
	this->front->next = NULL;
	this->front->data = NULL;
	this->QueueLength = 0;
	return 0;
}

int Queue::DestroyQueue() {
	//销毁队列Q
	while (this->front) {
		this->rear = this->front->next;
		delete this->front;
		this->front = this->rear;
	}
	return 0;
}

int Queue::EnterQueue(Passenger e) {
	//插入元素e为Q的新的队尾元素
	PassengerList* p;
	p = new PassengerList();
	if (!p)
		return OVERFLOW;
	p->data = e; p->next = NULL;
	this->rear->next = p;
	this->rear = p;
	this->QueueLength++;
	return 0;
}

int Queue::DeleteQueue(Passenger& e) { //带头结点的队列
	//若队列不空,则删除Q的队头元素,用e返回其值,并返回0;
	//否则返回ERROR
	PassengerList* p;
	if (this->front == this->rear)  //如果队列为空，则返回错误
		return -1;
	p = this->front->next;    //绕过头结点
	e = p->data;
	this->front->data = e;
	this->front->next = p->next;
	if (this->rear == p)
		this->rear = this->front;
	delete p;
	this->QueueLength--;
	return 0;
}

bool Queue::IsQueueEmpty() {
	//判断队列是否为空
	if (this->front == this->rear)
		return 1;
	else
		return 0;
}