Composite（组合）

8. Composite（组合）

8.1定义

　　将对象组合成树形结构以表示“部分—整体”的层次结构，使得用户对单个对象和组合对象的使用具有一致性

8.2 优点

　　■ 高层模块调用简单。一棵树形机构中的所有节点都是 Component，局部和整体对调用者来说没有任何区别，即高层模块不必关心自己处理的是单个对象还是整个组合结构，简化了高层模块的代码。

　　■ 节点自由增加。使用组合模式后，如果想增加一个树枝节点、树叶节点只需要找到其父节点即可。

8.3 缺点

　　■ 不易控制树枝构件的类型；

　　■ 不易使用继承的方法来增加新的行为。

8.4 使用场景

　　■ 需要描述对象的部分和整体的等级结构，如树形菜单、文件和文件夹管理。

　　■ 需要客户端忽略个体构件和组合构件的区别，平等对待所有的构件。组合模式也是应用广泛的一种设计模式。

8.5 c++源码实例

#include<iostream>
#include <list>
#include <memory>
#include <stdio.h>
#include <string>
using namespace std;

//
class Company {
public:
    virtual string getInfo() = 0;
    virtual  string getName()
    {
        return name;
    }
    virtual string getType() = 0;
protected:
    string name;
    string position;
    int salary;
};
class ConcreteCompany :public Company {
public:
    ConcreteCompany(string name, string position, int salary) {
        this->name = name;
        this->position = position;
        this->salary = salary;
    }
    void add(Company* company) {

        shared_ptr<Company> temp(company);
        companyList.push_back(temp);
    }
    string getType() {
        return "ConcreteCompany";
    }
    void remove(string companyName) {
        list<shared_ptr<Company>>::iterator iter = companyList.begin();
            for (; iter != companyList.end(); iter++)
            {
                    if ((*iter).get()->getName() == companyName)
                    {
                        companyList.erase(iter);
                        return;
                    }
            }
    }
    list<shared_ptr<Company>> getChild() {
        return companyList;
    }
    string getInfo() {
        string info = "";
        info = "名称：" + this->name;
        info = info + "\t职位：" + this->position;
        info = info + "\t薪水：" + to_string(this->salary);
        return info;
    }
private:
    list<shared_ptr<Company>> companyList;
};

class Employee :public Company {
public:
    Employee(string name, string position, int salary) {
        this->name = name;
        this->position = position;
        this->salary = salary;
    }
    string getType() {
        return "Employee";
    }
    string getInfo() {
        string info = "";
        info = "名称：" + this->name;
        info = info + "\t职位：" + this->position;
        info = info + "\t薪水：" + to_string(this->salary);
        return info;
    }
};
void disPlay(ConcreteCompany* root) {

    cout << root->getInfo() << endl;
    list<shared_ptr<Company>> tmp = root->getChild();
    list<shared_ptr<Company>>::iterator iter = tmp.begin();
    for (; iter != tmp.end(); iter++)
    {
        if ((*iter).get()->getType() == string("Employee"))
        {
            cout << (*iter).get()->getInfo() << endl;
        }
        else {
            disPlay((ConcreteCompany*)(*iter).get());
        }
    }

}
int main() {
    ConcreteCompany* root = new ConcreteCompany("张三", "CEO", 100000);
    ConcreteCompany* develop = new ConcreteCompany("李四", "研发组长", 100000);
    ConcreteCompany* sale = new ConcreteCompany("王二", "销售组长", 100000);
    Employee *e1 = new Employee("A", "研发",200);
    Employee *e2 = new Employee("B", "销售", 200);
    Employee *e3 = new Employee("C", "研发", 200);
    Employee *e4 = new Employee("D", "销售", 200);
    root->add(develop);
    root->add(sale);
    develop->add(e1);
    develop->add(e3);
    sale->add(e2);
    sale->add(e4);
    disPlay(root);
    develop->remove("A");
    disPlay(root);
    delete root;
    root = NULL;

}