Composite（組合）--對象結構型模式

1.意圖

    將對象組合成樹形結構以表示“部分-整體”的層次結構。Composite使得用戶對單個對象和組合對象的使用具有一致性。

2.動機

    可以組合多個簡單組件以形成一些較大的組件，這些組件又可以組合成更大的組件。Composite模式描述瞭如何使用遞歸組合，使得用戶不必對這些類進行區別。

3.適用性

• 表示對象的部分-整體層次結構。
• 希望用戶忽略組合對象與單個對象的不同，用戶將統一地使用組合結構中的所有對象。

4.結構

    5.代碼實例

#include <memory>
#include <vector>

class Graphic
{
public:
    Graphic(std::shared_ptr<Graphic> pParent);
    virtual void Add(std::shared_ptr<Graphic>& pGraphic);
    virtual void Remove(std::shared_ptr<Graphic>& pGraphic);
    virtual std::shared_ptr<Graphic> GetChild(int iIndex);
    virtual std::shared_ptr<Graphic>& GetParent();
    virtual void Opereate();

protected:
    std::shared_ptr<Graphic> m_pParent;

    std::vector<std::shared_ptr<Graphic>> m_vecChildrenGraphics;

}; 

class Circle : public Graphic
{
public:
    Circle(std::shared_ptr<Graphic> pParent);
    void Opereate();
};


class Retangle : public Graphic
{
public:
    Retangle(std::shared_ptr<Graphic> pParent);
    void Opereate();
};


class Line : public Graphic
{
public:
    Line(std::shared_ptr<Graphic> pParent);
    void Opereate();
};

class Picture : public Graphic
{
public:
    Picture(std::shared_ptr<Graphic> pParent);
    virtual void Add(std::shared_ptr<Graphic>& pGraphic);
    virtual void Remove(std::shared_ptr<Graphic>& pGraphic);
    virtual std::shared_ptr<Graphic> GetChild(int iIndex);
    void Opereate();
};

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


Graphic::Graphic(std::shared_ptr<Graphic> pParent) 
    : m_pParent(pParent)
{
}

 void Graphic::Add(std::shared_ptr<Graphic>& pGraphic)
 {
     std::cout<< "Leaf Cannot Add Childrren" << std::endl;
 }

 void Graphic::Remove(std::shared_ptr<Graphic>& pGraphic)
 {
     std::cout<< "Leaf Cannot Remove Childrren" << std::endl;
 }

 std::shared_ptr<Graphic> Graphic::GetChild(int iIndex)
 {
     std::cout<< "Leaf Cannot Get Child" << std::endl;
     return nullptr;
 }

 std::shared_ptr<Graphic>& Graphic::GetParent()
 {
     return m_pParent;
 }

 void Graphic::Opereate()
 {
     std::cout<< "Default Operate Executed" <<std::endl;
 }

 Circle::Circle(std::shared_ptr<Graphic> pParent)
     :Graphic(pParent)
 {
 }

 void Circle::Opereate()
 {
     std::cout << "Circle Operate Exeeuted" << std::endl;
 }

 Retangle::Retangle(std::shared_ptr<Graphic> pParent)
     :Graphic(pParent)
 {
 }

 void Retangle::Opereate()
 {
     std::cout << "Retangle Operate Exeeuted" << std::endl;
 }


  Line::Line(std::shared_ptr<Graphic> pParent)
     :Graphic(pParent)
 {
 }

 void Line::Opereate()
 {
     std::cout << "Line Operate Exeeuted" << std::endl;
 }


 Picture::Picture(std::shared_ptr<Graphic> pParent) 
    : Graphic(pParent)
{
}

 void Picture::Add(std::shared_ptr<Graphic>& pGraphic)
 {
     m_vecChildrenGraphics.push_back(pGraphic);

     std::cout<< "ChildrenGraphics Add Success" <<std::endl;
 }

 void Picture::Remove(std::shared_ptr<Graphic>& pGraphic)
 {
     for(auto iter=m_vecChildrenGraphics.begin();
         iter!=m_vecChildrenGraphics.end();++iter)
     {
         if((*iter) == pGraphic)
         {
             m_vecChildrenGraphics.erase(iter);
             std::cout<< "ChildrenGraphics remove Success"<<std::endl;
             break;
         }
     }
 }

 std::shared_ptr<Graphic> Picture::GetChild(int iIndex)
 {
     auto count = m_vecChildrenGraphics.size();
     if(iIndex <= count -1)
     {
         std::cout<< "Get Child Success" <<std::endl;
         return m_vecChildrenGraphics[iIndex];
     }

     return nullptr;
 }

 void Picture::Opereate()
 {
     for(auto iter=m_vecChildrenGraphics.begin();
         iter!=m_vecChildrenGraphics.end();++iter)
     {
         (*iter)->Opereate();
     }
 }

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

int main()
{
    std::shared_ptr<Graphic> pPicture(new Picture(nullptr));

    std::shared_ptr<Graphic> pCircle(new Circle(pPicture));

    std::shared_ptr<Graphic> pRetangle(new Retangle(pPicture));

    std::shared_ptr<Graphic> pLine(new Line(pPicture));

    pPicture->Add(pCircle);
    pPicture->Add(pRetangle);
    pPicture->Add(pLine);

    pPicture->Opereate();

    if(nullptr == pPicture->GetParent())
    {
        std::cout<< "pPicture is root" <<std::endl;
    }

    auto pNode = pPicture->GetChild(0);

    auto pParent = pNode->GetParent();

    if(nullptr != pParent)
    {
        std::cout<<"Node has Parent"<<std::endl;
    }

    std::cout << "Parent Operate:"<<std::endl;

    pParent->Opereate();

    pNode->Opereate();

    pNode->Add(pNode);

    pNode->Remove(pNode);

    pNode->GetChild(0);


    pNode = pPicture->GetChild(1);

    if(nullptr != pNode->GetParent())
    {
        std::cout<<"Node has Parent"<<std::endl;
    }

    pNode->Opereate();

    pNode->Add(pNode);

    pNode->Remove(pNode);

    pNode->GetChild(0);

     pNode = pPicture->GetChild(2);

    if(nullptr != pNode->GetParent())
    {
        std::cout<<"Node has Parent"<<std::endl;
    }

    pNode->Opereate();

    pNode->Add(pNode);

    pNode->Remove(pNode);

    pNode->GetChild(0);

    pPicture->Remove(pCircle);
    pPicture->Remove(pRetangle);
    pPicture->Remove(pLine);


    while(1);

    



}

6.測試結果 

7.效果

• 定義了包含基本對象和組合對象的類層次結構 基本對象可以被組合成更複雜的組合對象，而這個組合對象又可以被組合。
• 簡化客戶代碼 客戶可以一致地使用組合結構和單個對象。
• 使得容易增加新類型的組件 新定義的Composite或Leaf子類自動地與已有的結構和客戶代碼一起工作，客戶程式不需因新的Component類而改變。
• 使設計變的更加一般化。