void NINJAKUN::action()
{
  switch(m_state)
  {
    case STOP: stop(); break;
    case MOVE: move(); break;
    case JUMP: jump(); break;
  }
}

void NINJAKUN::stop()
{
  if(isKeyDown(LEFT)){ m_direction = LEFT; m_state = MOVE; }
  else if(isKeyDown(RIGHT)){ m_direction = RIGHT; m_state = MOVE; }
  else if(isKeyDown(JUMP)){ m_state = JUMP; }
}

void NINJAKUN::move()
{
  if(isKeyDown(LEFT)){ m_position.x -= IDOURYOU; }
  else if(isKeyDown(RIGHT)){ m_position.x += IDOURYOU; }
  else { m_state = STOP; }
}

void NINJAKUN::jump()
{
  if(isKeyDown(LEFT)){ m_position.x -= IDOURYOU; }
  else if(isKeyDown(RIGHT)){ m_position.x += IDOURYOU; }
}

みたいな