Reduce heap allocations by getting rid of temporary std::list and std::string

components/esp_modem/include/cxx_include/esp_modem_command_library.hpp

@@ -31,9 +31,9 @@ namespace dce_commands {
  * @param fail_phrase String to be present in the reply to fail this command
  * @param timeout_ms Timeout in ms
  */
-command_result generic_command(CommandableIf *t, const std::string &command,
-                               const std::string &pass_phrase,
-                               const std::string &fail_phrase, uint32_t timeout_ms);
+command_result generic_command(CommandableIf *t, std::string_view command,
+                               std::string_view pass_phrase,
+                               std::string_view fail_phrase, uint32_t timeout_ms);
 
 /**
  * @brief Declaration of all commands is generated from esp_modem_command_declare.inc

components/esp_modem/include/cxx_include/esp_modem_command_library_utils.hpp

@@ -6,6 +6,9 @@
 
 #pragma once
 
+#include <string_view>
+#include <span>
+
 namespace esp_modem::dce_commands {
 
 /**
@@ -17,9 +20,9 @@ namespace esp_modem::dce_commands {
  * @param timeout_ms Command timeout in ms
  * @return Generic command return type (OK, FAIL, TIMEOUT)
  */
-command_result generic_command(CommandableIf *t, const std::string &command,
-                               const std::string &pass_phrase,
-                               const std::string &fail_phrase, uint32_t timeout_ms);
+command_result generic_command(CommandableIf *t, std::string_view command,
+                               std::string_view pass_phrase,
+                               std::string_view fail_phrase, uint32_t timeout_ms);
 
 /**
  * @brief Utility command to send command and return reply (after DCE says OK)
@@ -29,7 +32,7 @@ command_result generic_command(CommandableIf *t, const std::string &command,
  * @param timeout_ms Command timeout in ms
  * @return Generic command return type (OK, FAIL, TIMEOUT)
  */
-template <typename T> command_result generic_get_string(CommandableIf *t, const std::string &command, T &output, uint32_t timeout_ms = 500);
+template <typename T> command_result generic_get_string(CommandableIf *t, std::string_view command, T &output, uint32_t timeout_ms = 500);
 
 /**
  * @brief Generic command that passes on "OK" and fails on "ERROR"
@@ -38,6 +41,6 @@ template <typename T> command_result generic_get_string(CommandableIf *t, const
  * @param timeout_ms Command timeout in ms
  * @return Generic command return type (OK, FAIL, TIMEOUT)
  */
-command_result generic_command_common(CommandableIf *t, const std::string &command, uint32_t timeout_ms = 500);
+command_result generic_command_common(CommandableIf *t, std::string_view command, uint32_t timeout_ms = 500);
 
 } // esp_modem::dce_commands

components/esp_modem/include/cxx_include/esp_modem_dce.hpp

@@ -74,7 +74,7 @@ public:
         return device.get();
     }
 
-    command_result command(const std::string &command, got_line_cb got_line, uint32_t time_ms)
+    command_result command(std::string_view command, got_line_cb got_line, uint32_t time_ms)
     {
         return dte->command(command, std::move(got_line), time_ms);
     }

components/esp_modem/include/cxx_include/esp_modem_dte.hpp

@@ -108,12 +108,12 @@ public:
      * @param time_ms Time in ms to wait for the answer
      * @return OK, FAIL, TIMEOUT
      */
-    command_result command(const std::string &command, got_line_cb got_line, uint32_t time_ms) override;
+    command_result command(std::string_view command, got_line_cb got_line, uint32_t time_ms) override;
 
     /**
      * @brief Sends the command (same as above) but with a specific separator
      */
-    command_result command(const std::string &command, got_line_cb got_line, uint32_t time_ms, char separator) override;
+    command_result command(std::string_view command, got_line_cb got_line, uint32_t time_ms, char separator) override;
 
     /**
      * @brief Allows this DTE to recover from a generic connection issue

components/esp_modem/include/cxx_include/esp_modem_types.hpp

@@ -79,8 +79,8 @@ public:
      * @param separator Character treated as a line separator, typically '\n'
      * @return OK, FAIL or TIMEOUT
      */
-    virtual command_result command(const std::string &command, got_line_cb got_line, uint32_t time_ms, const char separator) = 0;
-    virtual command_result command(const std::string &command, got_line_cb got_line, uint32_t time_ms) = 0;
+    virtual command_result command(std::string_view command, got_line_cb got_line, uint32_t time_ms, const char separator) = 0;
+    virtual command_result command(std::string_view command, got_line_cb got_line, uint32_t time_ms) = 0;
 
     virtual int write(uint8_t *data, size_t len) = 0;
     virtual void on_read(got_line_cb on_data) = 0;