第34课 栈的概念及实现（上）

#ifndef _STACK_H_
#define _STACK_H_

#include "Object.h"

namespace DTLib
{

template <typename T>
class Stack : public Object
{
public:
    virtual void push(const T& elem) = 0;
    virtual void pop() = 0;
    virtual T top() const = 0;
    virtual void clear() = 0;
    virtual int size() const = 0;
};

}

#endif // _STACK_H_

#ifndef _STATICSTACK_H_
#define _STATICSTACK_H_

#include "Stack.h"
#include "Exception.h"

namespace DTLib
{

template <typename T, int N>
class StaticStack : public Stack<T>
{
protected:
    T m_space[N]; //栈存储空间，N为模板参数
    int m_top;    //栈顶标识
    int m_size;   //当前栈的大小
public:
    StaticStack()   //O(1)
    {
        m_top = -1;
        m_size = 0;
    }

    int capacity() const  //O(1)
    {
        return N;
    }

    void push(const T& elem)  //O(1)
    {
        if(m_size < N){
            //要注意确保异常安全，即如果T类的“=”操作符发生异常时
            //m_top和m_size没被改变。
            m_space[m_top + 1] = elem;
            m_top++;
            m_size++;
        }else{
            THROW_EXCEPTION(InvalidOperationException, "No space in current stack ...");
        }
    }

    void pop()  //O(1)
    {
        if(m_size > 0){
            m_top--;
            m_size--;
        }else{
            THROW_EXCEPTION(InvalidOperationException, "No element in current stack ...");
        }
    }

    T top() const //O(1)
    {
        if(m_size > 0){
            return m_space[m_top];
        }else{
            THROW_EXCEPTION(InvalidOperationException, "No element in current stack ...");
        }
    }

    void clear()  //O(1)
    {
        m_top = -1;
        m_size = 0;
    }

    int size() const  //O(1)
    {
        return m_size;
    }

};

}

#endif // _STATICSTACK_H_

#include <iostream>
#include "StaticStack.h"

using namespace std;
using namespace DTLib;

int main()
{
    StaticStack<int, 10> stack;

    try{
        stack.pop();
    }catch(const Exception& e){
        cout << e.message() << endl;
        cout << e.location() << endl;
    }

    for(int i=0; i<10; i++){
        stack.push(i);
    }

    while(stack.size() > 0){
        cout << stack.top() << " ";
        stack.pop();
    }

    cout << endl;

    return 0;
}
/*输出结果
No element in current stack ...
..\DTLib\StaticStack.h:48
9 8 7 6 5 4 3 2 1 0
*/