optimization related with std::string allocation in TelegramParser::tryExtractJsonValueStr

Author: w0lek

vpr/src/server/telegramparser.cpp

@@ -7,24 +7,26 @@ namespace comm {
 
 std::optional<std::string> TelegramParser::tryExtractJsonValueStr(const std::string& jsonString, const std::string& key)
 {
+    static const std::string end_key_pattern{"\":\""};
+
     // Find the position of the key
-    size_t keyPos = jsonString.find("\"" + key + "\":");
+    size_t keyPos = jsonString.find('\"' + key + end_key_pattern);
 
     if (keyPos == std::string::npos) {
         // Key not found
         return std::nullopt;
     }
 
     // Find the position of the value after the key
-    size_t valuePosStart = jsonString.find("\"", keyPos + key.length() + std::string("\":\"").size());
+    size_t valuePosStart = jsonString.find('\"', keyPos + key.length() + end_key_pattern.size());
 
     if (valuePosStart == std::string::npos) {
         // Value not found
         return std::nullopt;
     }
 
     // Find the position of the closing quote for the value
-    size_t valueEnd = jsonString.find("\"", valuePosStart + std::string("\"").size());
+    size_t valueEnd = jsonString.find('\"', valuePosStart + sizeof('\"'));
 
     if (valueEnd == std::string::npos) {
         // Closing quote not found