设计模式9——组合模式

组合模式中，整体和部分可以同等看待，基类设定一个节点接口，可以派生出叶子节点和非叶子节点。叶子节点不能添加节点，非叶子节点可以添加，组成一个典型的树形结构。

组合模式在游戏引擎的渲染树中应用很广泛。

Composite.h内容

#ifndef Composite_H_H
#define Composite_H_H

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

class Composite
{
public:
    Composite(string str) : name(str) {}
    virtual ~Composite() {}
    virtual void add(Composite *composite) = 0;
    virtual void display() = 0;
protected:
    string name;
};

class Leaf : public Composite
{
public:
    Leaf(string str) : Composite(str) {}
    virtual void add(Composite *composite) {}
    virtual void display() { cout << name << " "; }
private:

};

class Component : public Composite
{
public:
    Component(string str) : Composite(str) { }
    virtual void add(Composite *composite) { vecChildren.push_back(composite); }
    virtual void display(){
        cout << name << " " << endl;
        for(size_t i=0; i<vecChildren.size(); ++i){
            vecChildren[i]->display();
        }
    }
private:
    vector<Composite*> vecChildren;
};

void CompositeTest()
{
    Composite *com1 = new Component("A");
    Composite *leaf1 = new Leaf("B");
    Composite *leaf2 = new Leaf("C");
    com1->add(leaf1);
    com1->add(leaf2);

    Composite *com2 = new Component("D");
    Composite *leaf4 = new Leaf("E");
    Composite *leaf5 = new Leaf("F");
    com2->add(leaf4);
    com2->add(leaf5);

    com1->add(com2);

    com1->display();

}

#endif