visitor.cpp

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

// Forward declaration
class InsuranceAgent;

// Abstract element (place to visit)
class Building {
public:
    virtual void Accept(InsuranceAgent* agent) = 0;
    virtual ~Building() {}
};

// Concrete elements
class House : public Building {
public:
    void Accept(InsuranceAgent* agent) override;
};

class Bank : public Building {
public:
    void Accept(InsuranceAgent* agent) override;
};

class Factory : public Building {
public:
    void Accept(InsuranceAgent* agent) override;
};

// Visitor interface
class InsuranceAgent {
public:
    virtual void VisitHouse(House* house) = 0;
    virtual void VisitBank(Bank* bank) = 0;
    virtual void VisitFactory(Factory* factory) = 0;
    virtual ~InsuranceAgent() {}
};

// Concrete visitor
class BeginnerAgent : public InsuranceAgent {
public:
    void VisitHouse(House* house) override {
        cout << "Offer medical insurance to the family.\n";
    }
    void VisitBank(Bank* bank) override {
        cout << "Offer robbery insurance to the bank.\n";
    }
    void VisitFactory(Factory* factory) override {
        cout << "Offer fire and flood insurance to the factory.\n";
    }
};

// Implement Accept methods
void House::Accept(InsuranceAgent* agent) {
    agent->VisitHouse(this);
}
void Bank::Accept(InsuranceAgent* agent) {
    agent->VisitBank(this);
}
void Factory::Accept(InsuranceAgent* agent) {
    agent->VisitFactory(this);
}

// Demo
int main() {
    vector<Building*> buildings;
    buildings.push_back(new House());
    buildings.push_back(new Bank());
    buildings.push_back(new Factory());

    InsuranceAgent* agent = new BeginnerAgent();

    for (Building* b : buildings) {
        b->Accept(agent);
    }

    // cleanup
    for (Building* b : buildings) {
        delete b;
    }
    delete agent;

    system("pause");
    return 0;
}