c++组合模式

1.组合模式简介

   组合模式（Composite Pattern），又叫部分整体模式，是用于把一组相似的对象当作一个单一的对象。组合模式依据树形结构来组合对象，用来表示部分以及整体层次。

2.源码实现

#include <iostream>
#include <string>
#include <vector>
#include <algorithm>

using namespace std;

class ComponentPtr
{
protected:
    string m_strName;

public:
    ComponentPtr(string str)
    {
        m_strName = str;
    }

    virtual void add(ComponentPtr *p) = 0;
    virtual void remove(ComponentPtr *p) = 0;
    virtual void display() = 0;
};

class LeafPtr : public ComponentPtr
{
public:
    LeafPtr(string str) : ComponentPtr(str){};

    void add(ComponentPtr *p)
    {
        cout << "Leaf cannot add" << endl;
    }

    void remove(ComponentPtr *p)
    {
        cout << "Leaf cannot remove" << endl;
    }

    void display()
    {
        cout << m_strName << endl;
    }
};

class CompositePtr : public ComponentPtr
{
private:
    vector<ComponentPtr *> m_vec;

public:
    CompositePtr(string str) : ComponentPtr(str){};
    ~CompositePtr()
    {
        if(!m_vec.empty())
        {
            m_vec.clear();
        }
    }

    void add(ComponentPtr *p)
    {
        m_vec.push_back(p);
    }

    void remove(ComponentPtr *p)
    {
        vector<ComponentPtr *>::iterator it;

        for(it=m_vec.begin(); it!=m_vec.end(); it++)
        {
            if(*it == p)
            {
                m_vec.erase(it);
                break;
            }
        }
    }

    void display()
    {
        vector<ComponentPtr *>::iterator it;

        for(it=m_vec.begin(); it!=m_vec.end(); it++)
        {
            (*it)->display();
        }
    }
};

int main(int argc, char **argv)
{
    ComponentPtr *u[6];

    u[0] = new LeafPtr("总部财务部门");
    u[1] = new LeafPtr("总部人力资源部门");
    u[2] = new LeafPtr("上海分部财务部门");
    u[3] = new LeafPtr("上海分部人力资源部门");
    u[4] = new CompositePtr("上海分部");
    u[5] = new CompositePtr("总部");

    CompositePtr *p = (CompositePtr *)u[5];
    p->add(u[0]);
    p->add(u[1]);
    CompositePtr *p1 = (CompositePtr *)u[4];
    p1->add(u[2]);
    p1->add(u[3]);
    p->add(p1);

    p->display();

    delete u[0];
    delete u[1];
    delete u[2];
    delete u[3];
    delete u[4];
    delete u[5];

    return 0;
}

3.编译源码

$ g++ -o example example.cpp

4.运行及其结果

$ ./example
总部财务部门
总部人力资源部门
上海分部财务部门
上海分部人力资源部门