Groups.hh

#pragma once

#include <string>
#include <unordered_set>
#include "entityx/Entity.h"
#include "entityx/Event.h"


class Groups : public entityx::Receiver<Groups> {
public:
  Groups(entityx::EventManager &events) {
    events.subscribe<entityx::EntityDestroyedEvent>(*this);
  }

  void add(const std::string &group, entityx::Entity entity) {
    groups_[group].insert(entity);
  }

  void remove(const std::string &group, entityx::Entity entity) {
    groups_[group].erase(entity);
  }

  const std::unordered_set<entityx::Entity> &group(const std::string &name) {
    return groups_[name];
  }

  void receive(const entityx::EntityDestroyedEvent &event) {
    for (auto it : groups_) {
      auto f = it.second.find(event.entity);
      if (f != it.second.end()) {
        it.second.erase(f);
      }
    }
  }

private:
  std::unordered_map<std::string, std::unordered_set<entityx::Entity>> groups_;
};