package second_term.second_week;

import second_term.first_week.EmptyCollectionException;
import second_term.first_week.StackADT;

public class LindedStack<T> implements StackADT<T> {

    private int count;//用于计算栈中元素的个数
    private LinearNode<T> top;//指向顶栈的指针
    public LindedStack(){
        count = 0 ;
        top  = null;
    }

    @Override
    public T pop() {
        if (isEmpty())
            throw new EmptyCollectionException("Stack");

        T result = top.getElement();
        top = top.getNext();
        count--;
        return result;
    }

    @Override
    public void push(T element) {
        LinearNode<T> temp = new LinearNode<T>(element);

        temp.setNext(top);
        top = temp;
        count++;
    }

    @Override
    public T peek() throws EmptyCollectionException
    {
        if (isEmpty()){
            throw new EmptyCollectionException("Stack");}

            T result = top.getElement();
        return result;
    }

    @Override
    public boolean isEmpty() {
        if (count == 0)
            return true;
        else
            return false;
    }

    @Override
    public int Size() {
        return count;
    }

    public String toString(){
        String result="";
        for (int i =0;i<count;i++){
            System.out.println(top.getElement());
            top = top.getNext();
        }
        return result;
    }
}