#include <iostream>
#include <vector> using namespace std; #define DESTROY_POINTER(ptr) if (ptr) { delete ptr; ptr = NULL; } class Element; class Visitor
{
public:
virtual void Visit(Element* pElement)=;
}; class ConcreteVisitorA : public Visitor
{
public:
void Visit(Element* pElement);
}; class ConcreteVisitorB : public Visitor
{
public:
void Visit(Element* pElement);
}; class Element
{
public:
virtual void Accept(Visitor* pVisitor)=;
virtual void Interface1()=;
virtual void Interface2()=;
}; class ConcreteElementA : public Element
{
public:
void Accept(Visitor* pVisitor)
{
pVisitor->Visit(this);
}
void Interface1() { cout<<"ConcreteElementA::Interface1"<<endl; }
void Interface2() { cout<<"ConcreteElementA::Interface2"<<endl; }
}; class ConcreteElementB : public Element
{
public:
void Accept(Visitor* pVisitor)
{
pVisitor->Visit(this);
}
void Interface1() { cout<<"ConcreteElementB::Interface1"<<endl; }
void Interface2() { cout<<"ConcreteElementB::Interface2"<<endl; }
}; void ConcreteVisitorA::Visit(Element* pElement)
{
pElement->Interface1();
} void ConcreteVisitorB::Visit(Element* pElement)
{
pElement->Interface2();
} class Structure
{
public:
virtual ~Structure()
{
for (unsigned int i = ; i < m_elementList.size(); i++)
{
delete m_elementList[i];
}
m_elementList.clear();
} void Accept(Visitor* pVisitor)
{
for (unsigned int i = ; i < m_elementList.size(); i++)
{
m_elementList[i]->Accept(pVisitor);
}
} void AddElement(Element* pElement)
{
m_elementList.push_back(pElement);
}
private:
vector<Element*> m_elementList;
}; int main(int argc, char *argv[])
{
Structure structure; structure.AddElement(new ConcreteElementA);
structure.AddElement(new ConcreteElementB); Visitor* pVisitorA = new ConcreteVisitorA;
Visitor* pVisitorB = new ConcreteVisitorB; structure.Accept(pVisitorA);
structure.Accept(pVisitorB); DESTROY_POINTER(pVisitorA);
DESTROY_POINTER(pVisitorB); return ;
}