observer.hpp

// SPDX-License-Identifier: MIT
#ifndef LIBSBX_SIGNAL_OBSERVER_HPP_
#define LIBSBX_SIGNAL_OBSERVER_HPP_
 
#include <mutex>
#include <vector>
#include <functional>
 
#include <libsbx/signals/lockable.hpp>
 
namespace sbx::signals {
 
struct observer_type { };
 
template<typename Type>
constexpr auto is_observer_v = std::is_base_of_v<observer_type, std::remove_pointer_t<std::remove_reference_t<Type>>>;
 
template<lockable Lockable>
class observer_base : private observer_type {
 
  template <lockable, typename ...>
  friend class signal_base;
 
public:
 
  using lockable_type = Lockable;
 
  virtual ~observer_base() = default;
 
protected:
 
  void disconnect_all() {
    auto lock = std::unique_lock<lockable_type>{_mutex};
 
    _connections.clear();
  }
 
private:
 
  void add_connection(connection connection) {
    auto lock = std::unique_lock<lockable_type>{_mutex};
 
    _connections.emplace_back(std::move(connection));
  }
 
  lockable_type _mutex;
  std::vector<scoped_connection> _connections;
 
}; // class observer_base
 
using observer_st = observer_base<null_mutex>;
 
using observer_mt = observer_base<std::mutex>;
 
using observer = observer_mt;
 
} // namespace sbx::signals
 
#endif // LIBSBX_SIGNAL_OBSERVER_HPP_