c++设计模式----组合模式（Composite）

 什么是组合模式呢？

                               


DP书上给出的定义：将对象组合成树形结构以表示“部分-整体”的层次结构。组合使得用户对单个对象和组合对象的使用具有一致性。注意两个字“树形”。这种树形结构在现实生活中随处可见，比如一个集团公司，它有一个母公司，下设很多家子公司。不管是母公司还是子公司，都有各自直属的财务部、人力资源部、销售部等。对于母公司来说，不论是子公司，还是直属的财务部、人力资源部，都是它的部门。整个公司的部门拓扑图就是一个树形结构。

                                                                


意图：

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

你想表示对象的部分-整体层次结构。

你希望用户忽略组合对象与单个对象的不同，用户将统一地使用组合结构中的所有对象。

实现如下：

#include <iostream>
#include <vector>
#include <memory>
#include <string>
using namespace std;

class Company
{
public:
Company(string name) :m_name(name){}
virtual void add(Company *p) = 0;
virtual void remove(Company *p) = 0;
virtual void Print() = 0;
string GetName()
{
return m_name;
}

virtual ~Company(){}

private:
string m_name;
};

class ConcreteCompany :public Company
{
public:
ConcreteCompany(string name) :Company(name){};

void add(Company *p)
{
p_company.push_back(p);
}

void remove(Company *p)
{
for (vector<Company*>::iterator iter = p_company.begin(); iter != p_company.end(); ++iter)
{
if ((*iter)->GetName() == p->GetName())
{
if (*iter != NULL)
{
cout << "----delete1111111111111111111 " << (*iter)->GetName() << "----" << endl;
delete *iter;
*iter = NULL;
}
p_company.erase(iter);
break;
}
}
}

~ConcreteCompany()
{
vector<Company*>::iterator iter = p_company.begin();
while (iter != p_company.end())
{
if (*iter != NULL)
{
cout << "----delete " << (*iter)->GetName() << "----" << endl;
delete *iter;
*iter = NULL;
}
p_company.erase(iter);
iter = p_company.begin();
}
}

virtual void Print()
{
for (vector<Company *>::iterator it = p_company.begin(); it != p_company.end(); ++it)
{
cout << (*it)->GetName() << endl;
}
}
private:
vector<Company*>  p_company;
};

class Leaf : public Company
{
public:
Leaf(string name) : Company(name)
{}
void Operation()
{
cout << "I'm " << GetName() << endl;
}
void add(Company *p){}
void remove(Company *p){}
void Print(){}
};

int main(int argc, char *argv[])
{
Company *pNode = new ConcreteCompany("Beijing Head Office");
Company *pNodeHr = new Leaf("Beijing Human Resources Department");
Company *pSubNodeSh = new ConcreteCompany("Shanghai Branch");
Company *pSubNodeCd = new ConcreteCompany("Chengdu Branch");
Company *pSubNodeBt = new ConcreteCompany("Baotou Branch");
pNode->add(pNodeHr);
pNode->add(pSubNodeSh);
pNode->add(pSubNodeCd);
pNode->add(pSubNodeBt);
pNode->Print();

Company *pSubNodeShHr = new Leaf("Shanghai Human Resources Department");
Company *pSubNodeShCg = new Leaf("Shanghai Purchasing Department");
Company *pSubNodeShXs = new Leaf("Shanghai Sales department");
Company *pSubNodeShZb = new Leaf("Shanghai Quality supervision Department");
pSubNodeSh->add(pSubNodeShHr);
pSubNodeSh->add(pSubNodeShCg);
pSubNodeSh->add(pSubNodeShXs);
pSubNodeSh->add(pSubNodeShZb);
pNode->Print();

// 公司不景气，需要关闭上海质量监督部门
pSubNodeSh->remove(pSubNodeShZb);
if (pNode != NULL)
{
delete pNode;
pNode = NULL;
}
return 0;
}

使用智能指针管理上面的代码中指针：

             

#include <iostream>
#include <vector>
#include <memory>
#include <string>
using namespace std;

class Company
{
public:
Company(string name) :m_name(name){}
virtual void add(shared_ptr<Company> p) = 0;
virtual void remove(shared_ptr<Company> p) = 0;
string GetName()
{
return m_name;
}

virtual void Show(int denpth) {}

virtual ~Company(){}

private:
string m_name;
};

class ConcreteCompany :public Company
{
public:
ConcreteCompany(string name) :Company(name){};

void add(shared_ptr<Company> p)
{
p_company.push_back(p);
}

void remove(shared_ptr<Company> p)
{
for (vector<shared_ptr<Company>>::iterator iter = p_company.begin(); iter != p_company.end(); ++iter)
{
if ((*iter)->GetName() == p->GetName())
{
p_company.erase(iter);
}
}
}

void Show(int denpth)
{
for (int i = 0; i < denpth; i++)
cout << "-";
cout << GetName() << endl;
for (vector<shared_ptr<Company>>::iterator it = p_company.begin(); it != p_company.end(); ++it)
{
(*it)->Show(denpth+2);
}
}

~ConcreteCompany(){}

private:
vector<shared_ptr<Company>>  p_company;
};

class Leaf_F : public Company
{
public:
Leaf_F(string name) : Company(name){}

void add(shared_ptr<Company> p){}
void remove(shared_ptr<Company> p){}
shared_ptr<Company> GetChild(int index)
{
return NULL;
}

void Show(int denpth)
{
for (int i = 0; i < denpth; i++)
cout << "-";
cout << GetName() << endl;
}

~Leaf_F(){}
};

class Leaf_M : public Company
{
public:
Leaf_M(string name) : Company(name){}

void add(shared_ptr<Company> p){}
void remove(shared_ptr<Company> p){}
shared_ptr<Company> GetChild(int index)
{
return NULL;
}

void Show(int denpth)
{
for (int i = 0; i < denpth; i++)
cout << "-";
cout << GetName() << endl;
}

~Leaf_M(){}
};

int main()
{
//总公司
shared_ptr<Company> root(new ConcreteCompany("总公司"));
shared_ptr<Company> leaf1(new Leaf_F("财务部"));
shared_ptr<Company> leaf2(new Leaf_M("人力资源部"));
root->add(leaf1);
root->add(leaf2);

//分公司A
shared_ptr<Company> mid1 = make_shared<ConcreteCompany>(ConcreteCompany("分公司A"));
shared_ptr<Leaf_F> leaf3 = make_shared<Leaf_F>(Leaf_F("财务部"));
shared_ptr<Leaf_M> leaf4 = make_shared<Leaf_M>(Leaf_M("人力资源部"));
mid1->add(leaf3);
mid1->add(leaf4);
root->add(mid1);

//分公司B
shared_ptr<Company> mid2 = make_shared<ConcreteCompany>(ConcreteCompany("分公司B"));
shared_ptr<Leaf_F> leaf5 = make_shared<Leaf_F>(Leaf_F("财务部"));
shared_ptr<Leaf_M> leaf6 = make_shared<Leaf_M>(Leaf_M("人力资源部"));
mid2->add(leaf5);
mid2->add(leaf6);
root->add(mid2);

root->Show(0);
}