[esp32_ble_server] Replace EventEmitter with direct callbacks to reduce memory usage (#10946)

CODEOWNERS

@@ -160,7 +160,6 @@ esphome/components/esp_ldo/* @clydebarrow
 esphome/components/espnow/* @jesserockz
 esphome/components/ethernet_info/* @gtjadsonsantos
 esphome/components/event/* @nohat
-esphome/components/event_emitter/* @Rapsssito
 esphome/components/exposure_notifications/* @OttoWinter
 esphome/components/ezo/* @ssieb
 esphome/components/ezo_pmp/* @carlos-sarmiento

esphome/components/esp32_ble_server/__init__.py

@@ -26,7 +26,7 @@ from esphome.const import (
 from esphome.core import CORE
 from esphome.schema_extractors import SCHEMA_EXTRACT
 
-AUTO_LOAD = ["esp32_ble", "bytebuffer", "event_emitter"]
+AUTO_LOAD = ["esp32_ble", "bytebuffer"]
 CODEOWNERS = ["@jesserockz", "@clydebarrow", "@Rapsssito"]
 DEPENDENCIES = ["esp32"]
 DOMAIN = "esp32_ble_server"

esphome/components/esp32_ble_server/ble_characteristic.cpp

@@ -73,7 +73,7 @@ void BLECharacteristic::notify() {
 void BLECharacteristic::add_descriptor(BLEDescriptor *descriptor) {
   // If the descriptor is the CCCD descriptor, listen to its write event to know if the client wants to be notified
   if (descriptor->get_uuid() == ESPBTUUID::from_uint16(ESP_GATT_UUID_CHAR_CLIENT_CONFIG)) {
-    descriptor->on(BLEDescriptorEvt::VectorEvt::ON_WRITE, [this](const std::vector<uint8_t> &value, uint16_t conn_id) {
+    descriptor->on_write([this](std::span<const uint8_t> value, uint16_t conn_id) {
       if (value.size() != 2)
         return;
       uint16_t cccd = encode_uint16(value[1], value[0]);
@@ -208,8 +208,9 @@ void BLECharacteristic::gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt
       if (!param->read.need_rsp)
         break;  // For some reason you can request a read but not want a response
 
-      this->EventEmitter<BLECharacteristicEvt::EmptyEvt, uint16_t>::emit_(BLECharacteristicEvt::EmptyEvt::ON_READ,
+      if (this->on_read_callback_) {
-                                                                          param->read.conn_id);
+        (*this->on_read_callback_)(param->read.conn_id);
+      }
 
       uint16_t max_offset = 22;
 
@@ -277,8 +278,9 @@ void BLECharacteristic::gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt
       }
 
       if (!param->write.is_prep) {
-        this->EventEmitter<BLECharacteristicEvt::VectorEvt, std::vector<uint8_t>, uint16_t>::emit_(
+        if (this->on_write_callback_) {
-            BLECharacteristicEvt::VectorEvt::ON_WRITE, this->value_, param->write.conn_id);
+          (*this->on_write_callback_)(this->value_, param->write.conn_id);
+        }
       }
 
       break;
@@ -289,8 +291,9 @@ void BLECharacteristic::gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt
         break;
       this->write_event_ = false;
       if (param->exec_write.exec_write_flag == ESP_GATT_PREP_WRITE_EXEC) {
-        this->EventEmitter<BLECharacteristicEvt::VectorEvt, std::vector<uint8_t>, uint16_t>::emit_(
+        if (this->on_write_callback_) {
-            BLECharacteristicEvt::VectorEvt::ON_WRITE, this->value_, param->exec_write.conn_id);
+          (*this->on_write_callback_)(this->value_, param->exec_write.conn_id);
+        }
       }
       esp_err_t err =
           esp_ble_gatts_send_response(gatts_if, param->write.conn_id, param->write.trans_id, ESP_GATT_OK, nullptr);

esphome/components/esp32_ble_server/ble_characteristic.h

@@ -2,10 +2,12 @@
 
 #include "ble_descriptor.h"
 #include "esphome/components/esp32_ble/ble_uuid.h"
-#include "esphome/components/event_emitter/event_emitter.h"
 #include "esphome/components/bytebuffer/bytebuffer.h"
 
 #include <vector>
+#include <span>
+#include <functional>
+#include <memory>
 
 #ifdef USE_ESP32
 
@@ -22,22 +24,10 @@ namespace esp32_ble_server {
 
 using namespace esp32_ble;
 using namespace bytebuffer;
-using namespace event_emitter;
 
 class BLEService;
 
-namespace BLECharacteristicEvt {
+class BLECharacteristic {
-enum VectorEvt {
-  ON_WRITE,
-};
-
-enum EmptyEvt {
-  ON_READ,
-};
-}  // namespace BLECharacteristicEvt
-
-class BLECharacteristic : public EventEmitter<BLECharacteristicEvt::VectorEvt, std::vector<uint8_t>, uint16_t>,
-                          public EventEmitter<BLECharacteristicEvt::EmptyEvt, uint16_t> {
  public:
   BLECharacteristic(ESPBTUUID uuid, uint32_t properties);
   ~BLECharacteristic();
@@ -76,6 +66,15 @@ class BLECharacteristic : public EventEmitter<BLECharacteristicEvt::VectorEvt, s
   bool is_created();
   bool is_failed();
 
+  // Direct callback registration - only allocates when callback is set
+  void on_write(std::function<void(std::span<const uint8_t>, uint16_t)> &&callback) {
+    this->on_write_callback_ =
+        std::make_unique<std::function<void(std::span<const uint8_t>, uint16_t)>>(std::move(callback));
+  }
+  void on_read(std::function<void(uint16_t)> &&callback) {
+    this->on_read_callback_ = std::make_unique<std::function<void(uint16_t)>>(std::move(callback));
+  }
+
  protected:
   bool write_event_{false};
   BLEService *service_{};
@@ -98,6 +97,9 @@ class BLECharacteristic : public EventEmitter<BLECharacteristicEvt::VectorEvt, s
   void remove_client_from_notify_list_(uint16_t conn_id);
   ClientNotificationEntry *find_client_in_notify_list_(uint16_t conn_id);
 
+  std::unique_ptr<std::function<void(std::span<const uint8_t>, uint16_t)>> on_write_callback_;
+  std::unique_ptr<std::function<void(uint16_t)>> on_read_callback_;
+
   esp_gatt_perm_t permissions_ = ESP_GATT_PERM_READ | ESP_GATT_PERM_WRITE;
 
   enum State : uint8_t {

esphome/components/esp32_ble_server/ble_descriptor.cpp

@@ -74,9 +74,10 @@ void BLEDescriptor::gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_
         break;
       this->value_.attr_len = param->write.len;
       memcpy(this->value_.attr_value, param->write.value, param->write.len);
-      this->emit_(BLEDescriptorEvt::VectorEvt::ON_WRITE,
+      if (this->on_write_callback_) {
-                  std::vector<uint8_t>(param->write.value, param->write.value + param->write.len),
+        (*this->on_write_callback_)(std::span<const uint8_t>(param->write.value, param->write.len),
                                     param->write.conn_id);
+      }
       break;
     }
     default:

esphome/components/esp32_ble_server/ble_descriptor.h

@@ -1,30 +1,26 @@
 #pragma once
 
 #include "esphome/components/esp32_ble/ble_uuid.h"
-#include "esphome/components/event_emitter/event_emitter.h"
 #include "esphome/components/bytebuffer/bytebuffer.h"
 
 #ifdef USE_ESP32
 
 #include <esp_gatt_defs.h>
 #include <esp_gatts_api.h>
+#include <span>
+#include <functional>
+#include <memory>
 
 namespace esphome {
 namespace esp32_ble_server {
 
 using namespace esp32_ble;
 using namespace bytebuffer;
-using namespace event_emitter;
 
 class BLECharacteristic;
 
-namespace BLEDescriptorEvt {
+// Base class for BLE descriptors
-enum VectorEvt {
+class BLEDescriptor {
-  ON_WRITE,
-};
-}  // namespace BLEDescriptorEvt
-
-class BLEDescriptor : public EventEmitter<BLEDescriptorEvt::VectorEvt, std::vector<uint8_t>, uint16_t> {
  public:
   BLEDescriptor(ESPBTUUID uuid, uint16_t max_len = 100, bool read = true, bool write = true);
   virtual ~BLEDescriptor();
@@ -39,6 +35,12 @@ class BLEDescriptor : public EventEmitter<BLEDescriptorEvt::VectorEvt, std::vect
   bool is_created() { return this->state_ == CREATED; }
   bool is_failed() { return this->state_ == FAILED; }
 
+  // Direct callback registration - only allocates when callback is set
+  void on_write(std::function<void(std::span<const uint8_t>, uint16_t)> &&callback) {
+    this->on_write_callback_ =
+        std::make_unique<std::function<void(std::span<const uint8_t>, uint16_t)>>(std::move(callback));
+  }
+
  protected:
   BLECharacteristic *characteristic_{nullptr};
   ESPBTUUID uuid_;
@@ -46,6 +48,8 @@ class BLEDescriptor : public EventEmitter<BLEDescriptorEvt::VectorEvt, std::vect
 
   esp_attr_value_t value_{};
 
+  std::unique_ptr<std::function<void(std::span<const uint8_t>, uint16_t)>> on_write_callback_;
+
   esp_gatt_perm_t permissions_{};
 
   enum State : uint8_t {

esphome/components/esp32_ble_server/ble_server.cpp

@@ -147,20 +147,28 @@ BLEService *BLEServer::get_service(ESPBTUUID uuid, uint8_t inst_id) {
   return nullptr;
 }
 
+void BLEServer::dispatch_callbacks_(CallbackType type, uint16_t conn_id) {
+  for (auto &entry : this->callbacks_) {
+    if (entry.type == type) {
+      entry.callback(conn_id);
+    }
+  }
+}
+
 void BLEServer::gatts_event_handler(esp_gatts_cb_event_t event, esp_gatt_if_t gatts_if,
                                     esp_ble_gatts_cb_param_t *param) {
   switch (event) {
     case ESP_GATTS_CONNECT_EVT: {
       ESP_LOGD(TAG, "BLE Client connected");
       this->add_client_(param->connect.conn_id);
-      this->emit_(BLEServerEvt::EmptyEvt::ON_CONNECT, param->connect.conn_id);
+      this->dispatch_callbacks_(CallbackType::ON_CONNECT, param->connect.conn_id);
       break;
     }
     case ESP_GATTS_DISCONNECT_EVT: {
       ESP_LOGD(TAG, "BLE Client disconnected");
       this->remove_client_(param->disconnect.conn_id);
       this->parent_->advertising_start();
-      this->emit_(BLEServerEvt::EmptyEvt::ON_DISCONNECT, param->disconnect.conn_id);
+      this->dispatch_callbacks_(CallbackType::ON_DISCONNECT, param->disconnect.conn_id);
       break;
     }
     case ESP_GATTS_REG_EVT: {

esphome/components/esp32_ble_server/ble_server.h

@@ -13,6 +13,7 @@
 #include <vector>
 #include <unordered_map>
 #include <unordered_set>
+#include <functional>
 
 #ifdef USE_ESP32
 
@@ -24,18 +25,7 @@ namespace esp32_ble_server {
 using namespace esp32_ble;
 using namespace bytebuffer;
 
-namespace BLEServerEvt {
+class BLEServer : public Component, public GATTsEventHandler, public BLEStatusEventHandler, public Parented<ESP32BLE> {
-enum EmptyEvt {
-  ON_CONNECT,
-  ON_DISCONNECT,
-};
-}  // namespace BLEServerEvt
-
-class BLEServer : public Component,
-                  public GATTsEventHandler,
-                  public BLEStatusEventHandler,
-                  public Parented<ESP32BLE>,
-                  public EventEmitter<BLEServerEvt::EmptyEvt, uint16_t> {
  public:
   void setup() override;
   void loop() override;
@@ -65,7 +55,25 @@ class BLEServer : public Component,
 
   void ble_before_disabled_event_handler() override;
 
+  // Direct callback registration - supports multiple callbacks
+  void on_connect(std::function<void(uint16_t)> &&callback) {
+    this->callbacks_.push_back({CallbackType::ON_CONNECT, std::move(callback)});
+  }
+  void on_disconnect(std::function<void(uint16_t)> &&callback) {
+    this->callbacks_.push_back({CallbackType::ON_DISCONNECT, std::move(callback)});
+  }
+
  protected:
+  enum class CallbackType : uint8_t {
+    ON_CONNECT,
+    ON_DISCONNECT,
+  };
+
+  struct CallbackEntry {
+    CallbackType type;
+    std::function<void(uint16_t)> callback;
+  };
+
   struct ServiceEntry {
     ESPBTUUID uuid;
     uint8_t inst_id;
@@ -76,6 +84,9 @@ class BLEServer : public Component,
 
   void add_client_(uint16_t conn_id) { this->clients_.insert(conn_id); }
   void remove_client_(uint16_t conn_id) { this->clients_.erase(conn_id); }
+  void dispatch_callbacks_(CallbackType type, uint16_t conn_id);
+
+  std::vector<CallbackEntry> callbacks_;
 
   std::vector<uint8_t> manufacturer_data_{};
   esp_gatt_if_t gatts_if_{0};

esphome/components/esp32_ble_server/ble_server_automations.cpp

@@ -14,9 +14,10 @@ Trigger<std::vector<uint8_t>, uint16_t> *BLETriggers::create_characteristic_on_w
     BLECharacteristic *characteristic) {
   Trigger<std::vector<uint8_t>, uint16_t> *on_write_trigger =  // NOLINT(cppcoreguidelines-owning-memory)
       new Trigger<std::vector<uint8_t>, uint16_t>();
-  characteristic->EventEmitter<BLECharacteristicEvt::VectorEvt, std::vector<uint8_t>, uint16_t>::on(
+  characteristic->on_write([on_write_trigger](std::span<const uint8_t> data, uint16_t id) {
-      BLECharacteristicEvt::VectorEvt::ON_WRITE,
+    // Convert span to vector for trigger
-      [on_write_trigger](const std::vector<uint8_t> &data, uint16_t id) { on_write_trigger->trigger(data, id); });
+    on_write_trigger->trigger(std::vector<uint8_t>(data.begin(), data.end()), id);
+  });
   return on_write_trigger;
 }
 #endif
@@ -25,9 +26,10 @@ Trigger<std::vector<uint8_t>, uint16_t> *BLETriggers::create_characteristic_on_w
 Trigger<std::vector<uint8_t>, uint16_t> *BLETriggers::create_descriptor_on_write_trigger(BLEDescriptor *descriptor) {
   Trigger<std::vector<uint8_t>, uint16_t> *on_write_trigger =  // NOLINT(cppcoreguidelines-owning-memory)
       new Trigger<std::vector<uint8_t>, uint16_t>();
-  descriptor->on(
+  descriptor->on_write([on_write_trigger](std::span<const uint8_t> data, uint16_t id) {
-      BLEDescriptorEvt::VectorEvt::ON_WRITE,
+    // Convert span to vector for trigger
-      [on_write_trigger](const std::vector<uint8_t> &data, uint16_t id) { on_write_trigger->trigger(data, id); });
+    on_write_trigger->trigger(std::vector<uint8_t>(data.begin(), data.end()), id);
+  });
   return on_write_trigger;
 }
 #endif
@@ -35,8 +37,7 @@ Trigger<std::vector<uint8_t>, uint16_t> *BLETriggers::create_descriptor_on_write
 #ifdef USE_ESP32_BLE_SERVER_ON_CONNECT
 Trigger<uint16_t> *BLETriggers::create_server_on_connect_trigger(BLEServer *server) {
   Trigger<uint16_t> *on_connect_trigger = new Trigger<uint16_t>();  // NOLINT(cppcoreguidelines-owning-memory)
-  server->on(BLEServerEvt::EmptyEvt::ON_CONNECT,
+  server->on_connect([on_connect_trigger](uint16_t conn_id) { on_connect_trigger->trigger(conn_id); });
-             [on_connect_trigger](uint16_t conn_id) { on_connect_trigger->trigger(conn_id); });
   return on_connect_trigger;
 }
 #endif
@@ -44,38 +45,22 @@ Trigger<uint16_t> *BLETriggers::create_server_on_connect_trigger(BLEServer *serv
 #ifdef USE_ESP32_BLE_SERVER_ON_DISCONNECT
 Trigger<uint16_t> *BLETriggers::create_server_on_disconnect_trigger(BLEServer *server) {
   Trigger<uint16_t> *on_disconnect_trigger = new Trigger<uint16_t>();  // NOLINT(cppcoreguidelines-owning-memory)
-  server->on(BLEServerEvt::EmptyEvt::ON_DISCONNECT,
+  server->on_disconnect([on_disconnect_trigger](uint16_t conn_id) { on_disconnect_trigger->trigger(conn_id); });
-             [on_disconnect_trigger](uint16_t conn_id) { on_disconnect_trigger->trigger(conn_id); });
   return on_disconnect_trigger;
 }
 #endif
 
 #ifdef USE_ESP32_BLE_SERVER_SET_VALUE_ACTION
 void BLECharacteristicSetValueActionManager::set_listener(BLECharacteristic *characteristic,
-                                                          EventEmitterListenerID listener_id,
                                                           const std::function<void()> &pre_notify_listener) {
   // Find and remove existing listener for this characteristic
   auto *existing = this->find_listener_(characteristic);
   if (existing != nullptr) {
-    // Remove the previous listener
-    characteristic->EventEmitter<BLECharacteristicEvt::EmptyEvt, uint16_t>::off(BLECharacteristicEvt::EmptyEvt::ON_READ,
-                                                                                existing->listener_id);
-    // Remove the pre-notify listener
-    this->off(BLECharacteristicSetValueActionEvt::PRE_NOTIFY, existing->pre_notify_listener_id);
     // Remove from vector
     this->remove_listener_(characteristic);
   }
-  // Create a new listener for the pre-notify event
-  EventEmitterListenerID pre_notify_listener_id =
-      this->on(BLECharacteristicSetValueActionEvt::PRE_NOTIFY,
-               [pre_notify_listener, characteristic](const BLECharacteristic *evt_characteristic) {
-                 // Only call the pre-notify listener if the characteristic is the one we are interested in
-                 if (characteristic == evt_characteristic) {
-                   pre_notify_listener();
-                 }
-               });
   // Save the entry to the vector
-  this->listeners_.push_back({characteristic, listener_id, pre_notify_listener_id});
+  this->listeners_.push_back({characteristic, pre_notify_listener});
 }
 
 BLECharacteristicSetValueActionManager::ListenerEntry *BLECharacteristicSetValueActionManager::find_listener_(

esphome/components/esp32_ble_server/ble_server_automations.h

@@ -4,7 +4,6 @@
 #include "ble_characteristic.h"
 #include "ble_descriptor.h"
 
-#include "esphome/components/event_emitter/event_emitter.h"
 #include "esphome/core/automation.h"
 
 #include <vector>
@@ -18,10 +17,6 @@ namespace esp32_ble_server {
 namespace esp32_ble_server_automations {
 
 using namespace esp32_ble;
-using namespace event_emitter;
-
-// Invalid listener ID constant - 0 is used as sentinel value in EventEmitter
-static constexpr EventEmitterListenerID INVALID_LISTENER_ID = 0;
 
 class BLETriggers {
  public:
@@ -41,38 +36,29 @@ class BLETriggers {
 };
 
 #ifdef USE_ESP32_BLE_SERVER_SET_VALUE_ACTION
-enum BLECharacteristicSetValueActionEvt {
-  PRE_NOTIFY,
-};
-
 // Class to make sure only one BLECharacteristicSetValueAction is active at a time for each characteristic
-class BLECharacteristicSetValueActionManager
+class BLECharacteristicSetValueActionManager {
-    : public EventEmitter<BLECharacteristicSetValueActionEvt, BLECharacteristic *> {
  public:
   // Singleton pattern
   static BLECharacteristicSetValueActionManager *get_instance() {
     static BLECharacteristicSetValueActionManager instance;
     return &instance;
   }
-  void set_listener(BLECharacteristic *characteristic, EventEmitterListenerID listener_id,
+  void set_listener(BLECharacteristic *characteristic, const std::function<void()> &pre_notify_listener);
-                    const std::function<void()> &pre_notify_listener);
+  bool has_listener(BLECharacteristic *characteristic) { return this->find_listener_(characteristic) != nullptr; }
-  EventEmitterListenerID get_listener(BLECharacteristic *characteristic) {
+  void emit_pre_notify(BLECharacteristic *characteristic) {
     for (const auto &entry : this->listeners_) {
       if (entry.characteristic == characteristic) {
-        return entry.listener_id;
+        entry.pre_notify_listener();
+        break;
       }
     }
-    return INVALID_LISTENER_ID;
-  }
-  void emit_pre_notify(BLECharacteristic *characteristic) {
-    this->emit_(BLECharacteristicSetValueActionEvt::PRE_NOTIFY, characteristic);
   }
 
  private:
   struct ListenerEntry {
     BLECharacteristic *characteristic;
-    EventEmitterListenerID listener_id;
+    std::function<void()> pre_notify_listener;
-    EventEmitterListenerID pre_notify_listener_id;
   };
   std::vector<ListenerEntry> listeners_;
 
@@ -87,24 +73,22 @@ template<typename... Ts> class BLECharacteristicSetValueAction : public Action<T
   void set_buffer(ByteBuffer buffer) { this->set_buffer(buffer.get_data()); }
   void play(Ts... x) override {
     // If the listener is already set, do nothing
-    if (BLECharacteristicSetValueActionManager::get_instance()->get_listener(this->parent_) == this->listener_id_)
+    if (BLECharacteristicSetValueActionManager::get_instance()->has_listener(this->parent_))
       return;
     // Set initial value
     this->parent_->set_value(this->buffer_.value(x...));
     // Set the listener for read events
-    this->listener_id_ = this->parent_->EventEmitter<BLECharacteristicEvt::EmptyEvt, uint16_t>::on(
+    this->parent_->on_read([this, x...](uint16_t id) {
-        BLECharacteristicEvt::EmptyEvt::ON_READ, [this, x...](uint16_t id) {
       // Set the value of the characteristic every time it is read
       this->parent_->set_value(this->buffer_.value(x...));
     });
     // Set the listener in the global manager so only one BLECharacteristicSetValueAction is set for each characteristic
     BLECharacteristicSetValueActionManager::get_instance()->set_listener(
-        this->parent_, this->listener_id_, [this, x...]() { this->parent_->set_value(this->buffer_.value(x...)); });
+        this->parent_, [this, x...]() { this->parent_->set_value(this->buffer_.value(x...)); });
   }
 
  protected:
   BLECharacteristic *parent_;
-  EventEmitterListenerID listener_id_;
 };
 #endif  // USE_ESP32_BLE_SERVER_SET_VALUE_ACTION
 

esphome/components/esp32_improv/esp32_improv_component.cpp

@@ -38,8 +38,7 @@ void ESP32ImprovComponent::setup() {
     });
   }
 #endif
-  global_ble_server->on(BLEServerEvt::EmptyEvt::ON_DISCONNECT,
+  global_ble_server->on_disconnect([this](uint16_t conn_id) { this->set_error_(improv::ERROR_NONE); });
-                        [this](uint16_t conn_id) { this->set_error_(improv::ERROR_NONE); });
 
   // Start with loop disabled - will be enabled by start() when needed
   this->disable_loop();
@@ -57,8 +56,7 @@ void ESP32ImprovComponent::setup_characteristics() {
   this->error_->add_descriptor(error_descriptor);
 
   this->rpc_ = this->service_->create_characteristic(improv::RPC_COMMAND_UUID, BLECharacteristic::PROPERTY_WRITE);
-  this->rpc_->EventEmitter<BLECharacteristicEvt::VectorEvt, std::vector<uint8_t>, uint16_t>::on(
+  this->rpc_->on_write([this](std::span<const uint8_t> data, uint16_t id) {
-      BLECharacteristicEvt::VectorEvt::ON_WRITE, [this](const std::vector<uint8_t> &data, uint16_t id) {
     if (!data.empty()) {
       this->incoming_data_.insert(this->incoming_data_.end(), data.begin(), data.end());
     }

esphome/components/event_emitter/__init__.py

@@ -1,5 +0,0 @@
-CODEOWNERS = ["@Rapsssito"]
-
-# Allows event_emitter to be configured in yaml, to allow use of the C++ api.
-
-CONFIG_SCHEMA = {}

esphome/components/event_emitter/event_emitter.h

@@ -1,117 +0,0 @@
-#pragma once
-#include <vector>
-#include <functional>
-#include <limits>
-
-#include "esphome/core/log.h"
-
-namespace esphome {
-namespace event_emitter {
-
-using EventEmitterListenerID = uint32_t;
-static constexpr EventEmitterListenerID INVALID_LISTENER_ID = 0;
-
-// EventEmitter class that can emit events with a specific name (it is highly recommended to use an enum class for this)
-// and a list of arguments. Supports multiple listeners for each event.
-template<typename EvtType, typename... Args> class EventEmitter {
- public:
-  EventEmitterListenerID on(EvtType event, std::function<void(Args...)> listener) {
-    EventEmitterListenerID listener_id = this->get_next_id_();
-
-    // Find or create event entry
-    EventEntry *entry = this->find_or_create_event_(event);
-    entry->listeners.push_back({listener_id, listener});
-
-    return listener_id;
-  }
-
-  void off(EvtType event, EventEmitterListenerID id) {
-    EventEntry *entry = this->find_event_(event);
-    if (entry == nullptr)
-      return;
-
-    // Remove listener with given id
-    for (auto it = entry->listeners.begin(); it != entry->listeners.end(); ++it) {
-      if (it->id == id) {
-        // Swap with last and pop for efficient removal
-        *it = entry->listeners.back();
-        entry->listeners.pop_back();
-
-        // Remove event entry if no more listeners
-        if (entry->listeners.empty()) {
-          this->remove_event_(event);
-        }
-        return;
-      }
-    }
-  }
-
- protected:
-  void emit_(EvtType event, Args... args) {
-    EventEntry *entry = this->find_event_(event);
-    if (entry == nullptr)
-      return;
-
-    // Call all listeners for this event
-    for (const auto &listener : entry->listeners) {
-      listener.callback(args...);
-    }
-  }
-
- private:
-  struct Listener {
-    EventEmitterListenerID id;
-    std::function<void(Args...)> callback;
-  };
-
-  struct EventEntry {
-    EvtType event;
-    std::vector<Listener> listeners;
-  };
-
-  EventEmitterListenerID get_next_id_() {
-    // Simple incrementing ID, wrapping around at max
-    EventEmitterListenerID next_id = (this->current_id_ + 1);
-    if (next_id == INVALID_LISTENER_ID) {
-      next_id = 1;
-    }
-    this->current_id_ = next_id;
-    return this->current_id_;
-  }
-
-  EventEntry *find_event_(EvtType event) {
-    for (auto &entry : this->events_) {
-      if (entry.event == event) {
-        return &entry;
-      }
-    }
-    return nullptr;
-  }
-
-  EventEntry *find_or_create_event_(EvtType event) {
-    EventEntry *entry = this->find_event_(event);
-    if (entry != nullptr)
-      return entry;
-
-    // Create new event entry
-    this->events_.push_back({event, {}});
-    return &this->events_.back();
-  }
-
-  void remove_event_(EvtType event) {
-    for (auto it = this->events_.begin(); it != this->events_.end(); ++it) {
-      if (it->event == event) {
-        // Swap with last and pop
-        *it = this->events_.back();
-        this->events_.pop_back();
-        return;
-      }
-    }
-  }
-
-  std::vector<EventEntry> events_;
-  EventEmitterListenerID current_id_ = 0;
-};
-
-}  // namespace event_emitter
-}  // namespace esphome