broadcaster.hh

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// SPDX-FileCopyrightText: 2021-2025 The Ikarus Developers ikarus@ibb.uni-stuttgart.de
// SPDX-License-Identifier: LGPL-3.0-or-later
 
#pragma once
#include <algorithm>
#include <functional>
#include <memory>
#include <vector>
 
namespace Ikarus {
 
template <typename MT, typename S>
class Broadcaster
{
public:
  using MessageType = MT;
  using State       = S;
 
  using Callback = std::function<void(MT, const State&)>;
  using Token    = std::shared_ptr<Callback>;
 
  Token registerListener(Callback callback) {
    auto sp = std::make_shared<Callback>(std::move(callback));
    listeners.push_back(sp);
    return sp;
  }
 
  void unregisterListener(Token token) {
    if (token) {
      token.reset();
    }
  }
 
  void notify(MT message, const State& data) {
    trim();
    for (auto& weakCb : listeners) {
      if (auto callback = weakCb.lock()) {
        (*callback)(message, data);
      }
    }
  }
 
private:
  std::vector<std::weak_ptr<Callback>> listeners;
 
  void trim() {
    listeners.erase(
        std::remove_if(listeners.begin(), listeners.end(), [](const auto& weakCb) { return weakCb.expired(); }),
        listeners.end());
  }
};
 
} // namespace Ikarus