hash_input_table.cpp

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

struct Event {
  Event(int akey, int ach) : key(akey), ch(ach) {}
  int key, ch;
  bool operator==(const Event &other) const {
  	return key == other.key || ch == other.ch;
  }
};

template <class T>
class Command2 {
public:
  virtual ~Command2() {}
  virtual void execute(T&) = 0;
};

struct Player {
  int x;
} player;

class NullCommand : public Command2<Player> {
public:
  virtual void execute(Player &p) {
    cout << "NullCommand" << endl;
  }
};

class MoveLeftCommand : public Command2<Player> {
public:
  virtual void execute(Player &p) {
    cout << "MoveLeftCommand" << endl;
    p.x -= 1;
  }
};

class EventTable {
private:
  vector<pair<Event, Command2<Player>*>> table;
  NullCommand nullCommand;
public:
  void setCommand (Event e, Command2<Player> &cmd) {
    for (auto &p : table) {
      if (p.first == e) {
        p.second = &cmd;
        return;
      }
    }
    table.push_back(make_pair(e, &cmd));
  }
  Command2<Player>* getCommand(Event e) {
    for (auto &p : table) {
      if (p.first == e) return p.second;
    }
    return &nullCommand;
  }
};

int main() {
  EventTable hashInputTable;
  hashInputTable.getCommand(Event(1, 1))->execute(player);
  MoveLeftCommand moveLeftCommand;
  hashInputTable.setCommand(Event(1, 1), moveLeftCommand);
  hashInputTable.getCommand(Event(1, 1))->execute(player);
  return 0;
}