Optimize DlmsParser allocations and types

Use stack buffers and C-strings to avoid heap allocations, and modernize token handling and ownership.

- Replace heap-allocated std::string temporaries in dlms_parser.cpp with stack buffers and pass const char* to callbacks/logs to reduce allocations and copying.
- Change DlmsDataCallback signature to accept const char* for obis and string values; update DlmsPushComponent to match.
- Switch DlmsParser ownership to std::unique_ptr in DlmsPushComponent and add <memory> include.
- Replace std::list with std::vector for DSL token parsing, update iteration/insertion logic accordingly.
- Remove unused <list> include and adjust related function signatures/whitespace.

These changes improve performance and memory usage; note the callback/API signature change may require updating any external callers.

components/dlms_push/dlms_parser.cpp

@@ -399,10 +399,9 @@ bool DlmsParser::match_pattern_(uint8_t elem_idx, const AxdrDescriptorPattern &p
 void DlmsParser::emit_object_(const AxdrDescriptorPattern &pat, const AxdrCaptures &c) {
   if (!c.obis || !this->callback_) return;
 
-  // Use stack-allocated buffer for OBIS to avoid string allocation
+  // Use stack-allocated buffer for OBIS to avoid heap allocation
   char obis_str_buf[32];
   this->obis_to_string_(c.obis, obis_str_buf, sizeof(obis_str_buf));
-  std::string obis_str(obis_str_buf);
 
   float raw_val_f = this->data_as_float_(c.value_type, c.value_ptr, c.value_len);
   float val_f = raw_val_f;
@@ -410,7 +409,6 @@ void DlmsParser::emit_object_(const AxdrDescriptorPattern &pat, const AxdrCaptur
   // Use stack-allocated buffer for formatting data
   char val_s_buf[128];
   this->data_to_string_(c.value_type, c.value_ptr, c.value_len, val_s_buf, sizeof(val_s_buf));
-  std::string val_s(val_s_buf);
 
   bool is_numeric = (c.value_type != DLMS_DATA_TYPE_OCTET_STRING &&
                      c.value_type != DLMS_DATA_TYPE_STRING &&
@@ -424,7 +422,7 @@ void DlmsParser::emit_object_(const AxdrDescriptorPattern &pat, const AxdrCaptur
     ESP_LOGD(TAG, "Pattern match '%s' at idx %u ===============", pat.name.c_str(), c.elem_idx);
     uint16_t cid = c.class_id ? c.class_id : pat.default_class_id;
 
-    ESP_LOGI(TAG, "Found attribute descriptor: class_id=%d, obis=%s", cid, obis_str.c_str());
+    ESP_LOGI(TAG, "Found attribute descriptor: class_id=%d, obis=%s", cid, obis_str_buf);
 
     if (c.has_scaler_unit) {
       ESP_LOGI(TAG, "Value type: %s, len %d, scaler %d, unit %d",
@@ -438,7 +436,7 @@ void DlmsParser::emit_object_(const AxdrDescriptorPattern &pat, const AxdrCaptur
       esphome::format_hex_pretty_to(hex_buf, sizeof(hex_buf), c.value_ptr, c.value_len);
       ESP_LOGI(TAG, " as hex dump : %s", hex_buf);
     }
-    ESP_LOGI(TAG, " as string   :'%s'", val_s.c_str());
+    ESP_LOGI(TAG, " as string   :'%s'", val_s_buf);
     ESP_LOGI(TAG, " as number   : %f", raw_val_f);
 
     if (c.has_scaler_unit && is_numeric) {
@@ -446,7 +444,7 @@ void DlmsParser::emit_object_(const AxdrDescriptorPattern &pat, const AxdrCaptur
     }
   }
 
-  this->callback_(obis_str, val_f, val_s, is_numeric);
+  this->callback_(obis_str_buf, val_f, val_s_buf, is_numeric);
   this->objects_found_++;
 }
 
@@ -620,7 +618,7 @@ void DlmsParser::register_pattern_dsl_(const std::string &name, const std::strin
     return s.substr(b, e - b + 1);
   };
 
-  std::list<std::string> tokens;
+  std::vector<std::string> tokens;
   std::string current;
   int paren = 0;
   for (char c : dsl) {
@@ -639,8 +637,8 @@ void DlmsParser::register_pattern_dsl_(const std::string &name, const std::strin
   }
   if (!current.empty()) tokens.push_back(trim(current));
 
-  for (auto it = tokens.begin(); it != tokens.end(); ++it) {
-    std::string tok = *it;
+  for (size_t i = 0; i < tokens.size(); i++) {
+    std::string tok = tokens[i];
     if (tok.empty()) continue;
 
     if (tok == "F") pat.steps.push_back({AxdrTokenType::EXPECT_TO_BE_FIRST});
@@ -671,7 +669,7 @@ void DlmsParser::register_pattern_dsl_(const std::string &name, const std::strin
       size_t r = tok.rfind(')');
       if (l != std::string::npos && r != std::string::npos && r > l + 1) {
         std::string inner = tok.substr(l + 1, r - l - 1);
-        std::list<std::string> inner_tokens;
+        std::vector<std::string> inner_tokens;
         std::string cur;
         for (char c2 : inner) {
           if (c2 == ',') {
@@ -685,9 +683,9 @@ void DlmsParser::register_pattern_dsl_(const std::string &name, const std::strin
 
         if (!inner_tokens.empty()) {
           pat.steps.push_back({AxdrTokenType::EXPECT_STRUCTURE_N, static_cast<uint8_t>(inner_tokens.size())});
-          inner_tokens.push_front("DN");
+          inner_tokens.insert(inner_tokens.begin(), "DN");
           inner_tokens.push_back("UP");
-          tokens.insert(std::next(it), inner_tokens.begin(), inner_tokens.end());
+          tokens.insert(tokens.begin() + i + 1, inner_tokens.begin(), inner_tokens.end());
         }
       }
     }

components/dlms_push/dlms_parser.h

@@ -4,7 +4,6 @@
 #include <functional>
 #include <string>
 #include <vector>
-#include <list>
 
 namespace esphome {
 namespace dlms_push {
@@ -37,7 +36,7 @@ enum DlmsDataType : uint8_t {
 };
 
 // Callback for the hub: OBIS code (e.g. "1.0.1.8.0.255"), numeric value, string value, is_numeric flag
-using DlmsDataCallback = std::function<void(const std::string &obis_code, float float_val, const std::string &str_val, bool is_numeric)>;
+using DlmsDataCallback = std::function<void(const char *obis_code, float float_val, const char *str_val, bool is_numeric)>;
 
 // --- Pattern Matching Enums & Structs ---
 enum class AxdrTokenType : uint8_t {

components/dlms_push/dlms_push.cpp

@@ -11,7 +11,7 @@ namespace dlms_push {
 static const char *const TAG = "dlms_push";
 
 DlmsPushComponent::DlmsPushComponent() {
-  this->parser_ = new DlmsParser();
+  this->parser_ = std::make_unique<DlmsParser>();
 }
 
 void DlmsPushComponent::setup() {
@@ -96,7 +96,7 @@ void DlmsPushComponent::process_frame_() {
     ESP_LOGD(TAG, "PUSH frame size: %zu bytes", this->rx_buffer_len_);
   }
 
-  auto callback = [this](const std::string &obis_code, float float_val, const std::string &str_val, bool is_numeric) {
+  auto callback = [this](const char *obis_code, float float_val, const char *str_val, bool is_numeric) {
     this->on_data_parsed_(obis_code, float_val, str_val, is_numeric);
   };
 
@@ -109,7 +109,7 @@ void DlmsPushComponent::process_frame_() {
   this->rx_buffer_len_ = 0;
 }
 
-void DlmsPushComponent::on_data_parsed_(const std::string &obis_code, float float_val, const std::string &str_val, bool is_numeric) {
+void DlmsPushComponent::on_data_parsed_(const char *obis_code, float float_val, const char *str_val, bool is_numeric) {
   int updated_count = 0;
 
 #ifdef USE_SENSOR
@@ -117,7 +117,7 @@ void DlmsPushComponent::on_data_parsed_(const std::string &obis_code, float floa
     for (const auto &entry : this->sensors_) {
       if (entry.obis == obis_code) {
         if (this->show_log_) {
-          ESP_LOGD(TAG, "Found sensor for OBIS code %s: '%s'", obis_code.c_str(), entry.sensor->get_name().c_str());
+          ESP_LOGD(TAG, "Found sensor for OBIS code %s: '%s'", obis_code, entry.sensor->get_name().c_str());
           ESP_LOGD(TAG, "Publishing data");
         }
         entry.sensor->publish_state(float_val);
@@ -131,7 +131,7 @@ void DlmsPushComponent::on_data_parsed_(const std::string &obis_code, float floa
   for (const auto &entry : this->text_sensors_) {
     if (entry.obis == obis_code) {
       if (this->show_log_) {
-        ESP_LOGD(TAG, "Found sensor for OBIS code %s: '%s'", obis_code.c_str(), entry.sensor->get_name().c_str());
+        ESP_LOGD(TAG, "Found sensor for OBIS code %s: '%s'", obis_code, entry.sensor->get_name().c_str());
         ESP_LOGD(TAG, "Publishing data");
       }
       entry.sensor->publish_state(str_val);
@@ -146,7 +146,7 @@ void DlmsPushComponent::on_data_parsed_(const std::string &obis_code, float floa
     for (const auto &entry : this->binary_sensors_) {
       if (entry.obis == obis_code) {
         if (this->show_log_) {
-          ESP_LOGD(TAG, "Found sensor for OBIS code %s: '%s'", obis_code.c_str(), entry.sensor->get_name().c_str());
+          ESP_LOGD(TAG, "Found sensor for OBIS code %s: '%s'", obis_code, entry.sensor->get_name().c_str());
           ESP_LOGD(TAG, "Publishing data");
         }
         entry.sensor->publish_state(state);
@@ -157,7 +157,7 @@ void DlmsPushComponent::on_data_parsed_(const std::string &obis_code, float floa
 #endif
 
   if (this->show_log_ && updated_count == 0) {
-    ESP_LOGV(TAG, "Received OBIS %s, but no sensors are registered for it.", obis_code.c_str());
+    ESP_LOGV(TAG, "Received OBIS %s, but no sensors are registered for it.", obis_code);
   }
 }
 

components/dlms_push/dlms_push.h

@@ -16,6 +16,7 @@
 #include <vector>
 #include <string>
 #include <array>
+#include <memory>
 
 namespace esphome {
 namespace dlms_push {
@@ -49,7 +50,7 @@ class DlmsPushComponent : public Component, public uart::UARTDevice {
   void read_rx_buffer_();
   void process_frame_();
 
-  void on_data_parsed_(const std::string &obis_code, float float_val, const std::string &str_val, bool is_numeric);
+  void on_data_parsed_(const char *obis_code, float float_val, const char *str_val, bool is_numeric);
 
   uint32_t receive_timeout_ms_{50};
   bool show_log_{false};
@@ -61,7 +62,7 @@ class DlmsPushComponent : public Component, public uart::UARTDevice {
   uint32_t last_rx_char_time_{0};
   bool receiving_{false};
 
-  DlmsParser *parser_{nullptr};
+  std::unique_ptr<DlmsParser> parser_;
 
 #ifdef USE_SENSOR
  struct NumericSensorEntry {