weird_crash.cpp

#include <vector>
#include <iostream>

class GameObject {
public:
  GameObject(void (*callback) ()) : callback(callback) {
  }

  ~GameObject() {
  }

  void update() {
    //    std::cout << "updated -> before callback\n";
    callback();
    //    std::cout << "updated -> after callback\n";
  }

private:
  void (*callback) ();
};

class MenuState {
public:
  void update() {
    std::cout << "update -> gameObjects.size(): " << gameObjects.size() << "\n";
    for (size_t i = 0; i < gameObjects.size(); i++) {
      std::cout << "update(for-loop: " << i << ") -> gameObjects.size(): " << gameObjects.size() << "\n";
      gameObjects[i]->update();
    }
  }

  bool onEnter() {
    GameObject* object1 = new GameObject(cllbckChangeState);
    GameObject* object2 = new GameObject(cllbckChangeState);

    gameObjects.push_back(object1);
    gameObjects.push_back(object2);

    return true;
  }

  bool onExit() {
    gameObjects.clear();
    return true;
  }

private:
  std::vector<GameObject*> gameObjects;
  static void cllbckChangeState();
};

class StateMachine {
public:
  static StateMachine* instance() {
    if (pInstance == 0) {
      pInstance = new StateMachine();
    }
    return pInstance;
  }

  void update() {
    std::cout << "StateMachine::update : menuStates.size(): " << menuStates.size() << "\n";

    if (!menuStates.empty()) {
      menuStates.back()->update();
    }
  }

  void pushState(MenuState* pState) {
    menuStates.push_back(pState);
    menuStates.back()->onEnter();
  }

  void popState() {
    if (!menuStates.empty()) {
      if (menuStates.back()->onExit()) {
        delete menuStates.back();
        menuStates.pop_back();
      }
    }

  }

  void switchState(MenuState* pState) {
    if (!menuStates.empty()) {
      popState();
      pushState(pState);
    }
  }

private:
  StateMachine() {
    MenuState* state1 = new MenuState();
    MenuState* state2 = new MenuState();
    menuStates.push_back(state1);
    menuStates.push_back(state2);
  }
  static StateMachine* pInstance;

  std::vector<MenuState*> menuStates;
};

StateMachine* StateMachine::pInstance = 0;

void MenuState::cllbckChangeState() {
  //  std::cout << "callback -> before switch\n";
  StateMachine::instance()->switchState(new MenuState());
  //  std::cout << "callback -> after switch\n";
}

int main () {
  StateMachine::instance()->pushState(new MenuState());
  long i = 1;
  while (true) {
    i++;
    std::cout << "tick: " << i << "\n";
    StateMachine::instance()->update();
  }
}