Composite

#include <vector>
#include <iostream>

using namespace std;



#define DO_NOTHING()
#define DESTROY_POINTER(ptr) if (ptr) { delete ptr; ptr = NULL; }



class Component
{
    friend class Composite;
    friend class Leaf;
public:
    virtual void Whoami()=0;
    virtual void AddChild(Component* pChild)=0;
    virtual void Whoareyou(int iIndex)=0;
    virtual void Travel(Component* pNode) = 0;
    
protected:
    vector<Component*> m_children;
};

class Composite : public Component
{
public:
    Composite() {}
    ~Composite();
    virtual void Whoami() { cout<<"I am a Composite"<<endl; }
    virtual void AddChild(Component* pChild) { m_children.push_back(pChild); }
    virtual void Whoareyou(int iIndex) { cout<<iIndex<<":"; m_children[iIndex]->Whoami(); }
    virtual void Travel(Component* pNode);
};




class Leaf : public Component
{
public:
    virtual void Whoami() { cout<<"I am a piece of Leaf"<<endl; }
    virtual void AddChild(Component* pChild) { DO_NOTHING(); }
    virtual void Whoareyou(int iIndex) { DO_NOTHING(); }
    virtual void Travel(Component* pNode) { Whoami(); }
};


Composite::~Composite()
{
    for (unsigned int i = 0; i < m_children.size(); i++)
    {
        Component* pTmp = m_children[i];
        DESTROY_POINTER(pTmp);
    }

    m_children.clear();
}

void Composite::Travel(Component* pNode)
{
    if (!pNode) pNode = this; // self
    pNode->Whoami();
    
    if (pNode->m_children.size() == 0) return ;
    
    for (unsigned int i = 0; i < pNode->m_children.size(); i++)
    {
        Travel(pNode->m_children[i]);
    }
}

int main(int argc, char *argv[])
{
    Component* pRoot, *pBranch1, *pBranch2;

    pRoot = new Composite;
    pRoot->AddChild(new Leaf);

    pBranch1 = new Composite;
    pRoot->AddChild(pBranch1);
    pBranch1->AddChild(new Leaf);
    pBranch1->AddChild(new Leaf);
     
    pBranch2 = new Composite;
    pBranch1->AddChild(pBranch2);
    pBranch2->AddChild(new Leaf);
    pBranch2->AddChild(new Leaf);
    pBranch2->AddChild(new Leaf);

    pRoot->Travel(NULL);

    DESTROY_POINTER(pRoot);
    DESTROY_POINTER(pBranch1);
    DESTROY_POINTER(pBranch2);

    return 0;
}