概念：將對(duì)象組合成樹形結(jié)構(gòu)以表示“部分-整體”的層次結(jié)構(gòu)。Composite使得用戶對(duì)單個(gè)對(duì)象和組合的使用具有一致性。

注意：組合模式有透明組合模式和安全組合模式。透明組合模式是將Addordinate和GetSubordinate這兩個(gè)函數(shù)也抽象到CCorpNode基類里，這增加了操作葉子節(jié)點(diǎn)的難度，更易出現(xiàn)邏輯問(wèn)題。所以盡量使用安全模式。

針對(duì)DrawingSystem中的基類Shape和各個(gè)子類Line、Rec、Circle，請(qǐng)使用某種模式來(lái)支持更復(fù)雜的形狀，該復(fù)雜形狀是各個(gè)形狀的自由組合。使用松耦合面向?qū)ο笤O(shè)計(jì)方法和思想,可使用偽碼表示設(shè)計(jì)。

經(jīng)過(guò)思考，認(rèn)為組合模式最適合這題目。
可以構(gòu)想將這些子類作為葉子，而葉子可以在掛載在同一個(gè)節(jié)點(diǎn)上，那么這個(gè)節(jié)點(diǎn)便是復(fù)雜形狀。由此，按照這個(gè)思路，完成了作業(yè)

//使用設(shè)計(jì)模式中的組合模式
//Shape為抽象基類
//ShapeNode 為節(jié)點(diǎn)類
//其他基本形狀為L(zhǎng)eaf。

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

class Shape
{
public:
    virtual ~Shape(){}
    virtual void Add(Shape *) = 0;           //加載元素
    virtual void Remove(unsigned int) = 0;   //移除指定位置元素
    virtual void Clear() = 0;                //清空元素
    virtual void GetInfo() = 0;              //獲取形狀信息
    virtual void Process() = 0;
};

class Line :public Shape
{
private:
    string info = "Line";
public:
    Line() { }
    void Add(Shape *pComponent){}
    void Remove(unsigned int num){}
    virtual void Clear() {}
    void GetInfo()
    {
        cout <<info << endl;
    }
    void Process()
    {
        //... 
    }
};

class Circle :public Shape
{
private:
    string info = "Circle";
public:
    Circle() { }
    void Add(Shape *pComponent){}
    void Remove(unsigned int num){}
    virtual void Clear() {}
    void GetInfo()
    {
        cout << info << endl;
    }
    void Process()
    {
        //... 
    }
};

class Rec :public Shape
{
private:
    string info = "Rec";
public:
    Rec() { }
    void Add(Shape *pComponent){}
    void Remove(unsigned int num){}
    virtual void Clear() {}
    void GetInfo()
    {
        cout <<info << endl;
    }
    void Process()
    {
        //... 
    }
};

class ShapeNode:public Shape
{
private:
    static int cnt;//用于統(tǒng)計(jì)有多少個(gè)節(jié)點(diǎn)
    int num;
    vector<Shape *> shapeNode;
public:
    typedef vector<Shape *>::iterator ShapeLiterator;
    ShapeNode(){ ++cnt; num = cnt; }
    ~ShapeNode()
    {
        ShapeLiterator it = shapeNode.begin();
        while (it != shapeNode.end())
        {
            if (*it != NULL)
            {
                delete *it;
                *it = NULL;
            }
            shapeNode.erase(it);
            it = shapeNode.begin();
        }
    }

    void Add(Shape *pComponent)
    {
        shapeNode.push_back(pComponent);
    }

    void Remove(unsigned int num)
    {
        if (num < shapeNode.size())
        {
            ShapeLiterator it = shapeNode.begin();
            shapeNode.erase(it + num);
        }
        else
        {
            cerr << "the num is OUT OF LIMIT, please Input again" << endl;
        }
    }
    void Clear()
    {
        if (!shapeNode.empty())
        {
            shapeNode.clear();
        }
    }

    void GetInfo()
    {
        if (!shapeNode.empty())
        {
            cout <<"I'm No."<<num<<" ShapeNode, I have "<<shapeNode.size()<< " Shapes:" << endl;
            for (ShapeLiterator it = shapeNode.begin(); it != shapeNode.end();it++)
            {
                (*it)->GetInfo();
            }
        }
        else
        {
            cout << "I'm No." << num << " ShapeNode, I have no Shapes!" << endl;
        }
    }
    void Process()
    {
        //... 
    }
};
int ShapeNode::cnt = 0;
void Process(Shape &shape)
{
    shape.Process();
}

int main()
{
    //創(chuàng)建第一個(gè)多組合形狀及其元素
    Shape *pShape1 = new ShapeNode();
    Shape *pLineLeaf1 = new Line();
    Shape *pLineLeaf2 = new Line();
    Shape *pCircleLeaf1 = new Circle();
    //加載元素
    pShape1->Add(pLineLeaf1);
    pShape1->Add(pLineLeaf2);
    pShape1->Add(pCircleLeaf1);
    pShape1->GetInfo();
    
    cout << endl;
    //創(chuàng)建第二個(gè)多組合形狀及其元素
    Shape *pShape2 = new ShapeNode();
    Shape *pRecLeaf1 = new Rec();
    Shape *pCircleLeaf2 = new Circle();
    Shape *pRecLeaf2 = new Rec();
    //加載元素
    pShape2->Add(pRecLeaf1);
    pShape2->Add(pCircleLeaf2);
    pShape2->Add(pRecLeaf2);
    pShape2->GetInfo();
    cout << endl;

    //測(cè)試刪除指定元素函數(shù)
    pShape2->Remove(1);
    pShape2->GetInfo();

    pShape2->Remove(4);

    //測(cè)試清空元素函數(shù)
    pShape2->Clear();
    cout << endl;
    pShape2->GetInfo();

    Process(pShape1);
    //... 


}