added output of used-defined attributes, use const where appropriate, enhanced http global node, added base class AttributedItem

src/ebusd/bushandler.cpp

@@ -211,7 +211,7 @@ void GrabbedMessage::setLastData(MasterSymbolString& master, SlaveSymbolString&
  * @param firstOnly whether to read only the first non-erroneous offset.
  * @return @a RESULT_OK on success, or an error code.
  */
-bool decodeType(DataType* type, SymbolString *input, size_t length,
+bool decodeType(const DataType* type, SymbolString *input, size_t length,
     size_t offsets, ostringstream& output, bool firstOnly = false) {
   bool first = true;
   string in = input->getStr(input->getDataOffset());
@@ -225,7 +225,7 @@ bool decodeType(DataType* type, SymbolString *input, size_t length,
       unsigned int value = 0;
       if (type->readRawValue(*input, offset, length, value) == RESULT_OK) {
         out.str("");
-        out << DataField::getDayName(reinterpret_cast<NumberDataType*>(type)->getMinValue()+value);
+        out << DataField::getDayName(reinterpret_cast<const NumberDataType*>(type)->getMinValue()+value);
       }
     }
     if (first) {
@@ -288,8 +288,8 @@ bool GrabbedMessage::dump(const bool unknown, MessageMap* messages, bool first,
     if (remain == 0) {
       return true;
     }
-    for (map<string, DataType*>::const_iterator it = types->begin(); it != types->end(); it++) {
+    for (auto it : *types) {
-      DataType* baseType = it->second;
+      const DataType* baseType = it.second;
       if ((baseType->getBitCount() % 8) != 0 || baseType->isIgnored()) {  // skip bit and ignored types
         continue;
       }
@@ -300,7 +300,7 @@ bool GrabbedMessage::dump(const bool unknown, MessageMap* messages, bool first,
       }
       if (baseType->isAdjustableLength()) {
         for (size_t length = maxLength; length >= 1; length--) {
-          DataType* type = types->get(baseType->getId(), length);
+          const DataType* type = types->get(baseType->getId(), length);
           if (decodeType(type, input, length, remain-length, output, firstOnly)) {
             if (firstOnly) {
               break;  // only a single offset with maximum length when adjustable maximum size is at least 8 bytes
@@ -1293,7 +1293,7 @@ void BusHandler::formatSeenInfo(ostringstream& output) {
         }
       }
     }
-    vector<string>& loadedFiles = m_messages->getLoadedFiles(address);
+    const vector<string>& loadedFiles = m_messages->getLoadedFiles(address);
     if (!loadedFiles.empty()) {
       bool first = true;
       for (auto& loadedFile : loadedFiles) {
@@ -1358,7 +1358,7 @@ void BusHandler::formatUpdateInfo(ostringstream& output) {
         message->decodeLastData(output, OF_NAMES|OF_NUMERIC|OF_JSON|OF_SHORT, true);
       }
     }
-    vector<string>& loadedFiles = m_messages->getLoadedFiles(address);
+    const vector<string>& loadedFiles = m_messages->getLoadedFiles(address);
     if (!loadedFiles.empty()) {
       output << ",\"f\":[";
       bool first = true;

src/ebusd/datahandler.h

@@ -73,7 +73,7 @@ class UserInfo {
    * @param user the user name.
    * @return whether the user exists.
    */
-  virtual bool hasUser(const string user) = 0;  // abstract
+  virtual bool hasUser(const string user) const = 0;  // abstract
 
   /**
    * Check whether the secret string matches the one of the specified user.
@@ -81,14 +81,14 @@ class UserInfo {
    * @param secret the secret to check.
    * @return whether the secret string is valid.
    */
-  virtual bool checkSecret(const string user, const string secret) = 0;  // abstract
+  virtual bool checkSecret(const string user, const string secret) const = 0;  // abstract
 
   /**
    * Get the access levels associated with the specified user.
    * @param user the user name, or empty for default levels.
    * @return the access levels separated by semicolon.
    */
-  virtual string getLevels(const string user) = 0;  // abstract
+  virtual string getLevels(const string user) const = 0;  // abstract
 };
 
 
@@ -116,13 +116,13 @@ class DataHandler {
    * Return whether this is a @a DataSink instance.
    * @return whether this is a @a DataSink instance.
    */
-  virtual bool isDataSink() { return false; }
+  virtual bool isDataSink() const { return false; }
 
   /**
    * Return whether this is a @a DataSource instance.
    * @return whether this is a @a DataSource instance.
    */
-  virtual bool isDataSource() { return false; }
+  virtual bool isDataSource() const { return false; }
 };
 
 
@@ -146,7 +146,7 @@ class DataSink : virtual public DataHandler {
   virtual ~DataSink() {}
 
   // @copydoc
-  bool isDataSink() override { return true; }
+  bool isDataSink() const override { return true; }
 
   /**
    * Notify the sink of an updated @a Message.
@@ -187,7 +187,7 @@ class DataSource : virtual public DataHandler {
   virtual ~DataSource() {}
 
   // @copydoc
-  bool isDataSource() override { return true; }
+  bool isDataSource() const override { return true; }
 
 
  protected:

src/ebusd/main.cpp

@@ -884,9 +884,9 @@ result_t loadScanConfigFile(MessageMap* messages, symbol_t address, string& rela
   if (!message) {
     return RESULT_ERR_NOTFOUND;
   }
-  SlaveSymbolString& data = message->getLastSlaveData();
+  const SlaveSymbolString& data = message->getLastSlaveData();
   if (data.getDataSize() < 1+5+2+2) {
-    logError(lf_main, "unable to load scan config %2.2x: slave part too short", address);
+    logError(lf_main, "unable to load scan config %2.2x: slave part too short (%d)", address, data.getDataSize());
     return RESULT_EMPTY;
   }
   DataFieldSet* identFields = DataFieldSet::getIdentFields();

src/ebusd/mainloop.cpp

@@ -41,7 +41,7 @@ using std::ifstream;
 #define RECONNECT_MISSING_SIGNAL 60
 
 
-result_t UserList::getFieldMap(vector<string>& row, string& errorDescription) {
+result_t UserList::getFieldMap(vector<string>& row, string& errorDescription) const {
   // name,secret,level[,level]*
   if (row.empty()) {
     row.push_back("name");
@@ -735,7 +735,7 @@ string MainLoop::executeRead(vector<string> &args, const string levels) {
     if (srcAddress == SYN
         && (message->getLastUpdateTime() + maxAge > now
             || (message->isPassive() && message->getLastUpdateTime() != 0))) {
-      SlaveSymbolString& slave = message->getLastSlaveData();
+      const SlaveSymbolString& slave = message->getLastSlaveData();
       logNotice(lf_main, "hex read %s %s from cache", message->getCircuit().c_str(), message->getName().c_str());
       return slave.getStr();
     }
@@ -998,7 +998,7 @@ string MainLoop::executeWrite(vector<string> &args, const string levels) {
         getResultCode(ret));
     return getResultCode(ret);
   }
-  dstAddress = message->getLastMasterData()[1];
+  dstAddress = message->getLastMasterData().dataAt(1);
   ostringstream result;
   if (dstAddress == BROADCAST || isMaster(dstAddress)) {
     logNotice(lf_main, "write %s %s: %s", message->getCircuit().c_str(), message->getName().c_str(),
@@ -1105,8 +1105,10 @@ string MainLoop::executeFind(vector<string> &args, string levels) {
       }
     } else if (args[argPos] == "-vv") {
       verbosity |= OF_NAMES|OF_UNITS;
-    } else if (args[argPos] == "-vvv" || args[argPos] == "-V") {
+    } else if (args[argPos] == "-vvv") {
       verbosity |= OF_NAMES|OF_UNITS|OF_COMMENTS;
+    } else if (args[argPos] == "-V") {
+      verbosity |= OF_NAMES|OF_UNITS|OF_COMMENTS|OF_ALL_ATTRS;
     } else if (args[argPos] == "-f") {
       configFormat = true;
       if (hexFormat) {
@@ -1251,12 +1253,12 @@ string MainLoop::executeFind(vector<string> &args, string levels) {
                << " / " << message->getLastSlaveData().getStr() << ")";
         }
       }
-      if (verbosity == (OF_NAMES|OF_UNITS|OF_COMMENTS)) {
+      if ((verbosity & (OF_NAMES|OF_UNITS|OF_COMMENTS)) == (OF_NAMES|OF_UNITS|OF_COMMENTS)) {
         symbol_t dstAddress = message->getDstAddress();
         if (dstAddress != SYN) {
           snprintf(str, sizeof(str), "%02x", dstAddress);
         } else if (lastup != 0 && message->getLastMasterData().size() > 1) {
-          snprintf(str, sizeof(str), "%02x", message->getLastMasterData()[1]);
+          snprintf(str, sizeof(str), "%02x", message->getLastMasterData().dataAt(1));
         } else {
           snprintf(str, sizeof(str), "any");
         }
@@ -1533,7 +1535,7 @@ string MainLoop::executeHelp() {
 
 string MainLoop::executeGet(vector<string> &args, bool& connected) {
   result_t ret = RESULT_OK;
-  bool numeric = false, required = false;
+  bool numeric = false, required = false, full = false;
   OutputFormat verbosity = OF_NAMES;
   size_t argPos = 1;
   string uri = args[argPos++];
@@ -1583,6 +1585,8 @@ string MainLoop::executeGet(vector<string> &args, bool& connected) {
           }
         } else if (qname == "numeric") {
           numeric = value.length() == 0 || value == "1";
+        } else if (qname == "full") {
+          full = value.length() == 0 || value == "1";
         } else if (qname == "required") {
           required = value.length() == 0 || value == "1";
         } else if (qname == "user") {
@@ -1639,6 +1643,7 @@ string MainLoop::executeGet(vector<string> &args, bool& connected) {
           }
           lastCircuit = message->getCircuit();
           result << "\n \"" << lastCircuit << "\": {";
+          // TODO add circuit specific values
           first = true;
         }
         if (first) {
@@ -1652,7 +1657,8 @@ string MainLoop::executeGet(vector<string> &args, bool& connected) {
           result << ",\n   \"zz\": \"" << setfill('0') << setw(2) << hex << static_cast<unsigned>(dstAddress) << "\"";
           size_t pos = (size_t) result.tellp();
           result << ",\n   \"fields\": {";
-          result_t dret = message->decodeLastData(result, verbosity | (numeric ? OF_NUMERIC : 0) | OF_JSON);
+          result_t dret = message->decodeLastData(
+              result, verbosity | (numeric ? OF_NUMERIC : 0) | OF_JSON | (full ? OF_ALL_ATTRS : 0));
           if (dret == RESULT_OK) {
             result << "\n   }";
           } else {
@@ -1671,7 +1677,25 @@ string MainLoop::executeGet(vector<string> &args, bool& connected) {
         result << "\n },";
       }
       result << "\n \"global\": {";
-      result << "\n  \"signal\": " << (m_busHandler->hasSignal() ? "1" : "0");
+      result << "\n  \"version\": \"" << PACKAGE_VERSION "." REVISION "\"";
+      if (!m_updateCheck.empty()) {
+        result << ",\n  \"updatecheck\": \"" << m_updateCheck << "\"";
+      }
+      if (!user.empty()) {
+        result << ",\n  \"user\": \"" << user << "\"";
+      }
+      string levels = getUserLevels(user);
+      if (!user.empty() || !levels.empty()) {
+        result << ",\n  \"access\": \"" << levels << "\"";
+      }
+      result << ",\n  \"signal\": " << (m_busHandler->hasSignal() ? "1" : "0");
+      if (m_busHandler->hasSignal()) {
+        result << ",\n  \"symbolrate\": " << m_busHandler->getSymbolRate();
+        result << ",\n  \"maxsymbolrate\": " << m_busHandler->getMaxSymbolRate();
+      }
+      result << ",\n  \"reconnects\": " << m_reconnectCount;
+      result << ",\n  \"masters\": " << m_busHandler->getMasterCount();
+      result << ",\n  \"messages\": " << m_messages->size();
       result << ",\n  \"lastup\": " << setw(0) << dec << static_cast<unsigned>(maxLastUp);
       result << "\n }";
       result << "\n}";

src/ebusd/mainloop.h

@@ -62,24 +62,28 @@ class UserList : public UserInfo, public MappedFileReader {
   virtual ~UserList() {}
 
   // @copydoc
-  result_t getFieldMap(vector<string>& row, string& errorDescription) override;
+  result_t getFieldMap(vector<string>& row, string& errorDescription) const override;
 
   // @copydoc
   result_t addFromFile(map<string, string>& row, vector< map<string, string> >& subRows,
       string& errorDescription, const string filename, unsigned int lineNo) override;
 
   // @copydoc
-  bool hasUser(const string user) override {
+  bool hasUser(const string user) const override {
     return m_userLevels.find(user) != m_userLevels.end();
   }
 
   // @copydoc
-  bool checkSecret(const string user, const string secret) override {
+  bool checkSecret(const string user, const string secret) const override {
-    return m_userSecrets.find(user) != m_userSecrets.end() && m_userSecrets[user] == secret;
+    auto it = m_userSecrets.find(user);
+    return it != m_userSecrets.end() && it->second == secret;
   }
 
   // @copydoc
-  string getLevels(const string user) override { return m_userLevels[user]; }
+  string getLevels(const string user) const override {
+    auto it = m_userLevels.find(user);
+    return it == m_userLevels.end() ? "" : it->second;
+  }
 
  private:
   /** the secret string by user name. */

src/lib/ebus/contrib/tem.cpp

@@ -39,7 +39,7 @@ void contrib_tem_register() {
   DataTypeList::getInstance()->add(new TemParamDataType("TEM_P"));
 }
 
-result_t TemParamDataType::derive(int divisor, size_t bitCount, NumberDataType* &derived) {
+result_t TemParamDataType::derive(int divisor, size_t bitCount, const NumberDataType* &derived) const {
   if (divisor == 0) {
     divisor = 1;
   }
@@ -53,9 +53,9 @@ result_t TemParamDataType::derive(int divisor, size_t bitCount, NumberDataType*
   return RESULT_ERR_INVALID_ARG;
 }
 
-result_t TemParamDataType::readSymbols(SymbolString& input,
+result_t TemParamDataType::readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) {
+    ostringstream& output, OutputFormat outputFormat) const {
   unsigned int value = 0;
 
   result_t result = readRawValue(input, offset, length, value);
@@ -92,7 +92,7 @@ result_t TemParamDataType::readSymbols(SymbolString& input,
 
 result_t TemParamDataType::writeSymbols(istringstream& input,
   const size_t offset, const size_t length,
-  SymbolString& output, size_t* usedLength) {
+  SymbolString& output, size_t* usedLength) const {
   unsigned int value;
   int grp, num;
   string token;

src/lib/ebus/contrib/tem.h

@@ -47,20 +47,20 @@ class TemParamDataType : public NumberDataType {
    * @param id the type identifier.
    */
   explicit TemParamDataType(const string id)
-    : NumberDataType(id, 16, 0, 0xffff, 0, 0xffff, 0) {}
+    : NumberDataType(id, 16, 0, 0xffff, 0, 0xffff, 0, NULL) {}
 
   // @copydoc
-  result_t derive(int divisor, size_t bitCount, NumberDataType* &derived) override;
+  result_t derive(int divisor, size_t bitCount, const NumberDataType* &derived) const override;
 
   // @copydoc
-  result_t readSymbols(SymbolString& input,
+  result_t readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) override;
+    ostringstream& output, OutputFormat outputFormat) const override;
 
   // @copydoc
   result_t writeSymbols(istringstream& input,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) override;
+    SymbolString& output, size_t* usedLength) const override;
 };
 
 /**

src/lib/ebus/contrib/test/test_tem.cpp

@@ -54,7 +54,7 @@ class TestReader : public MappedFileReader {
   TestReader(DataFieldTemplates* templates, bool isSet, bool isMasterDest)
   : MappedFileReader::MappedFileReader(true), m_templates(templates), m_isSet(isSet), m_isMasterDest(isMasterDest),
     m_fields(NULL) {}
-  result_t getFieldMap(vector<string>& row, string& errorDescription) override {
+  result_t getFieldMap(vector<string>& row, string& errorDescription) const override {
     if (row.empty()) {
       row.push_back("*name");
       row.push_back("part");
@@ -85,11 +85,11 @@ class TestReader : public MappedFileReader {
   const bool m_isSet;
   const bool m_isMasterDest;
  public:
-  DataField* m_fields;
+  const DataField* m_fields;
 };
 
 int main() {
-  DataType* type = DataTypeList::getInstance()->get("TEM_P");
+  const DataType* type = DataTypeList::getInstance()->get("TEM_P");
   if (type == NULL) {
     cout << "datatype not registered" << endl;
     return 1;
@@ -119,7 +119,7 @@ int main() {
   string errorDescription;
   vector<string> row;
   templates->readLineFromStream(dummystr, errorDescription, "inline", lineNo, row);
-  DataField* fields = NULL;
+  const DataField* fields = NULL;
   for (size_t i = 0; i < sizeof(checks) / sizeof(checks[0]); i++) {
     string check[5] = checks[i];
     istringstream isstr(check[0]);

src/lib/ebus/data.h

@@ -91,18 +91,116 @@ string getDataFieldName(const size_t fieldId);
 class DataFieldTemplates;
 class SingleDataField;
 
+/**
+ * Base class for named items with optional named attributes.
+ */
+class AttributedItem {
+ protected:
+  /**
+   * Constructs a new instance.
+   * @param name the item name.
+   * @param attributes the additional named attributes.
+   */
+  AttributedItem(const string name, const map<string, string>& attributes)
+    : m_name(name), m_attributes(attributes) {}
+
+  /**
+   * Constructs a new instance (without additional attributes).
+   * @param name the field name.
+   */
+  explicit AttributedItem(const string name)
+    : m_name(name) {}
+
+  /**
+   * Destructor.
+   */
+  virtual ~AttributedItem() {}
+
+
+ public:
+  /**
+   * Remove and return a certain value from a map.
+   * @param row the map to remove the value from.
+   * @param key the name of the value to remove.
+   * @return the named value from the map, or empty if not available.
+   */
+  static const string pluck(map<string, string>& row, const string key);
+
+  /**
+   * Dump the @a string optionally embedded in @a TEXT_SEPARATOR to the output.
+   * @param output the @a ostream to dump to.
+   * @param str the @a string to dump.
+   * @param prependFieldSeparator whether to start with a @a FIELD_SEPARATOR.
+   */
+  static void dumpString(ostream& output, const string str, const bool prependFieldSeparator = true);
+
+  /**
+   * Merge this instance's additional named attributes into the specified attributes.
+   * @param attributes the additional named attributes to merge in this instance's additional named attributes.
+   */
+  void mergeAttributes(map<string, string>& attributes) const;
+
+  /**
+   * Dump the attribute optionally embedded in @a TEXT_SEPARATOR to the output.
+   * @param output the @a ostream to dump to.
+   * @param name the name of the attribute to dump.
+   * @param prependFieldSeparator whether to start with a @a FIELD_SEPARATOR.
+   */
+  void dumpAttribute(ostream& output, const string name, const bool prependFieldSeparator = true) const;
+
+  /**
+   * Append the attribute value to the output.
+   * @param output the @a ostringstream to append the formatted value to.
+   * @param outputFormat the @a OutputFormat options to use.
+   * @param name the name of the attribute to append.
+   * @param onlyIfNonEmpty true to append only if the value is not empty.
+   * @param prefix optional prefix to use (only for non-JSON output).
+   * @param suffix optional suffix to use (only for non-JSON output).
+   */
+  void appendAttribute(ostringstream& output, OutputFormat outputFormat, const string name,
+      const bool onlyIfNonEmpty = true, const string prefix = "", const string suffix = "") const;
+
+  /**
+   * Get the item name.
+   * @return the item name.
+   */
+  string getName() const { return m_name; }
+
+  /**
+   * Get a named attribute.
+   * @param name the name of the attribute.
+   * @return the named attribute value, or empty.
+   */
+  string getAttribute(const string name) const;
+
+
+ protected:
+  /** the field name. */
+  const string m_name;
+
+  /** the additional named attributes. */
+  const map<string, string> m_attributes;
+};
+
 /**
  * Base class for all kinds of data fields.
  */
-class DataField {
+class DataField : public AttributedItem {
  public:
   /**
    * Constructs a new instance.
    * @param name the field name.
-   * @param comment the field comment.
+   * @param attributes the additional named attributes.
    */
-  DataField(const string name, const string comment)
+  DataField(const string name, const map<string, string>& attributes)
-    : m_name(name), m_comment(comment) {}
+    : AttributedItem(name, attributes) {}
+
+  /**
+   * Constructs a new instance (without additional attributes).
+   * @param name the field name.
+   */
+  explicit DataField(const string name)
+    : AttributedItem(name) {}
 
   /**
    * Destructor.
@@ -113,7 +211,7 @@ class DataField {
    * Clone this instance.
    * @return a clone of this instance.
    */
-  virtual DataField* clone() = 0;
+  virtual const DataField* clone() const = 0;
 
   /**
    * Factory method for creating new instances.
@@ -129,18 +227,10 @@ class DataField {
    * Note: the caller needs to free the created instance.
    */
   static result_t create(vector< map<string, string> >& rows, string& errorDescription,
-      DataFieldTemplates* templates, DataField*& returnField,
+    DataFieldTemplates* templates, const DataField*& returnField,
-      const bool isWriteMessage,
+    const bool isWriteMessage,
-      const bool isTemplate, const bool isBroadcastOrMasterDestination,
+    const bool isTemplate, const bool isBroadcastOrMasterDestination,
-      const size_t maxFieldLength = MAX_POS);
+    const size_t maxFieldLength = MAX_POS);
-
-  /**
-   * Dump the @a string optionally embedded in @a TEXT_SEPARATOR to the output.
-   * @param output the @a ostream to dump to.
-   * @param str the @a string to dump.
-   * @param prependFieldSeparator whether to start with a @a FIELD_SEPARATOR.
-   */
-  static void dumpString(ostream& output, const string str, const bool prependFieldSeparator = true);
 
   /**
    * Return the name of the specified day.
@@ -155,42 +245,33 @@ class DataField {
    * @param maxLength the maximum length for calculating remainder of input.
    * @return the length of this field (or contained fields) in bytes.
    */
-  virtual size_t getLength(PartType partType, size_t maxLength = MAX_LEN) = 0;
+  virtual size_t getLength(PartType partType, size_t maxLength = MAX_LEN) const = 0;
 
   /**
    * Derive a new @a DataField from this field.
    * @param name the field name, or empty to use this fields name.
-   * @param comment the field comment, or empty to use this fields comment.
+   * @param attributes the additional named attributes to override.
-   * @param unit the value unit, or empty to use this fields unit (if applicable).
    * @param partType the message part in which the field is stored.
    * @param divisor the extra divisor (negative for reciprocal) to apply on the value, or 1 for none (if applicable).
    * @param values the value=text assignments, or empty to use this fields assignments (if applicable).
    * @param fields the @a vector to which created @a SingleDataField instances shall be added.
    * @return @a RESULT_OK on success, or an error code.
    */
-  virtual result_t derive(string name, string comment,
+  virtual result_t derive(const string name, map<string, string> attributes, const PartType partType,
-      string unit, const PartType partType,
+    int divisor, map<unsigned int, string> values, vector<const SingleDataField*>& fields) const = 0;
-      int divisor, map<unsigned int, string> values,
-      vector<SingleDataField*>& fields) = 0;
 
   /**
    * Get the specified field name.
    * @param fieldIndex the index of the field, or -1 for this.
    * @return the field name, or the index as string if not unique or not available.
    */
-  virtual string getName(ssize_t fieldIndex = -1) { return m_name; }
+  virtual string getName(const ssize_t fieldIndex = -1) const { return m_name; }
-
-  /**
-   * Get the field comment.
-   * @return the field comment.
-   */
-  string getComment() const { return m_comment; }
 
   /**
    * Dump the field settings to the output.
    * @param output the @a ostream to dump to.
    */
-  virtual void dump(ostream& output) = 0;
+  virtual void dump(ostream& output) const = 0;
 
   /**
    * Return whether the field is available.
@@ -198,7 +279,7 @@ class DataField {
    * @param numeric true for a numeric field, false for a string field.
    * @return true if the field is available.
    */
-  virtual bool hasField(const char* fieldName, bool numeric) = 0;
+  virtual bool hasField(const char* fieldName, bool numeric) const = 0;
 
   /**
    * Reads the numeric value from the @a SymbolString.
@@ -212,8 +293,8 @@ class DataField {
    * not match or ignored, or due to @a fieldName or @a fieldIndex),
    * or an error code.
    */
-  virtual result_t read(SymbolString& data, size_t offset,
+  virtual result_t read(const SymbolString& data, size_t offset,
-      unsigned int& output, const char* fieldName = NULL, ssize_t fieldIndex = -1) = 0;
+    unsigned int& output, const char* fieldName = NULL, ssize_t fieldIndex = -1) const = 0;
 
   /**
    * Reads the value from the @a SymbolString.
@@ -229,9 +310,9 @@ class DataField {
    * or @a RESULT_EMPTY if the field was skipped (either ignored or due to @a fieldName or @a fieldIndex),
    * or an error code.
    */
-  virtual result_t read(SymbolString& data, size_t offset,
+  virtual result_t read(const SymbolString& data, size_t offset,
-      ostringstream& output, OutputFormat outputFormat, ssize_t outputIndex = -1,
+    ostringstream& output, OutputFormat outputFormat, ssize_t outputIndex = -1,
-      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) = 0;
+    bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) const = 0;
 
   /**
    * Writes the value to the master or slave @a SymbolString.
@@ -243,15 +324,7 @@ class DataField {
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t write(istringstream& input, SymbolString& data,
-      size_t offset, char separator = UI_FIELD_SEPARATOR, size_t* length = NULL) = 0;
+    size_t offset, char separator = UI_FIELD_SEPARATOR, size_t* length = NULL) const = 0;
-
-
- protected:
-  /** the field name. */
-  const string m_name;
-
-  /** the field comment. */
-  const string m_comment;
 };
 
 
@@ -263,18 +336,15 @@ class SingleDataField : public DataField {
   /**
    * Constructs a new instance.
    * @param name the field name.
-   * @param comment the field comment.
+   * @param attributes the additional named attributes.
-   * @param unit the value unit.
    * @param dataType the data type definition.
    * @param partType the message part in which the field is stored.
    * @param length the number of symbols in the message part in which the field is stored.
    */
-  SingleDataField(const string name, const string comment,
+  SingleDataField(const string name, const map<string, string>& attributes, const DataType* dataType,
-      const string unit, DataType* dataType, const PartType partType,
+    const PartType partType, const size_t length)
-      const size_t length)
+    : DataField(name, attributes),
-    : DataField(name, comment),
+    m_partType(partType), m_dataType(dataType), m_length(length) {}
-      m_unit(unit), m_dataType(dataType), m_partType(partType),
-      m_length(length) {}
 
   /**
    * Destructor.
@@ -282,16 +352,15 @@ class SingleDataField : public DataField {
   virtual ~SingleDataField() {}
 
   // @copydoc
-  SingleDataField* clone() override;
+  const SingleDataField* clone() const override;
 
   /**
    * Factory method for creating a new @a SingleDataField instance derived from a base type.
-   * @param id the ID string (excluding optional length suffix).
-   * @param length the base type length, or 0 for default, or @a REMAIN_LEN for remainder within same message part.
    * @param name the field name.
-   * @param comment the field comment.
+   * @param attributes the additional named attributes.
-   * @param unit the value unit.
    * @param partType the message part in which the field is stored.
+   * @param dataType the @a DataType instance.
+   * @param length the base type length, or 0 for default, or @a REMAIN_LEN for remainder within same message part.
    * @param divisor the extra divisor (negative for reciprocal) to apply on the value, or 1 for none (if applicable).
    * @param values the value=text assignments.
    * @param constantValue the constant value as string, or empty.
@@ -300,16 +369,9 @@ class SingleDataField : public DataField {
    * @return @a RESULT_OK on success, or an error code.
    * Note: the caller needs to free the created instance.
    */
-  static result_t create(const string id, const size_t length,
+  static result_t create(const string name, const map<string, string>& attributes, const DataType* dataType,
-      const string name, const string comment, const string unit,
+    const PartType partType, const size_t length, int divisor, map<unsigned int, string> values,
-      const PartType partType, int divisor, map<unsigned int, string> values,
+    const string constantValue, const bool verifyValue, SingleDataField* &returnField);
-      const string constantValue, const bool verifyValue, SingleDataField* &returnField);
-
-  /**
-   * Get the value unit.
-   * @return the value unit.
-   */
-  string getUnit() const { return m_unit; }
 
   /**
    * Get whether this field is ignored.
@@ -324,13 +386,11 @@ class SingleDataField : public DataField {
   PartType getPartType() const { return m_partType; }
 
   // @copydoc
-  size_t getLength(PartType partType, size_t maxLength = MAX_LEN) override;
+  size_t getLength(PartType partType, size_t maxLength = MAX_LEN) const override;
 
   // @copydoc
-  result_t derive(string name, string comment,
+  result_t derive(const string name, map<string, string> attributes, const PartType partType,
-      string unit, const PartType partType,
+    int divisor, map<unsigned int, string> values, vector<const SingleDataField*>& fields) const override;
-      int divisor, map<unsigned int, string> values,
-      vector<SingleDataField*>& fields) override;
 
   /**
    * Get whether this field uses a full byte offset.
@@ -338,26 +398,26 @@ class SingleDataField : public DataField {
    * @return @p true if this field uses a full byte offset, @p false if this field
    * only consumes a part of a byte and a subsequent field may re-use the same offset.
    */
-  bool hasFullByteOffset(bool after);
+  bool hasFullByteOffset(bool after) const;
 
   // @copydoc
-  void dump(ostream& output) override;
+  void dump(ostream& output) const override;
 
   // @copydoc
-  bool hasField(const char* fieldName, bool numeric) override;
+  bool hasField(const char* fieldName, bool numeric) const override;
 
   // @copydoc
-  result_t read(SymbolString& data, size_t offset,
+  result_t read(const SymbolString& data, size_t offset,
-      unsigned int& output, const char* fieldName = NULL, ssize_t fieldIndex = -1) override;
+    unsigned int& output, const char* fieldName = NULL, ssize_t fieldIndex = -1) const override;
 
   // @copydoc
-  result_t read(SymbolString& data, size_t offset,
+  result_t read(const SymbolString& data, size_t offset,
-      ostringstream& output, OutputFormat outputFormat, ssize_t outputIndex = -1,
+    ostringstream& output, OutputFormat outputFormat, ssize_t outputIndex = -1,
-      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) override;
+    bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) const override;
 
   // @copydoc
   result_t write(istringstream& input, SymbolString& data,
-      size_t offset, char separator = UI_FIELD_SEPARATOR, size_t* length = NULL) override;
+    size_t offset, char separator = UI_FIELD_SEPARATOR, size_t* length = NULL) const override;
 
 
  protected:
@@ -369,9 +429,9 @@ class SingleDataField : public DataField {
    * @param outputFormat the @a OutputFormat options to use.
    * @return @a RESULT_OK on success, or an error code.
    */
-  virtual result_t readSymbols(SymbolString& input,
+  virtual result_t readSymbols(const SymbolString& input,
-      const size_t offset,
+    const size_t offset,
-      ostringstream& output, OutputFormat outputFormat);
+    ostringstream& output, OutputFormat outputFormat) const;
 
   /**
    * Internal method for writing the field to a @a SymbolString.
@@ -382,18 +442,15 @@ class SingleDataField : public DataField {
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t writeSymbols(istringstream& input,
-      const size_t offset,
+    const size_t offset,
-      SymbolString& output, size_t* usedLength);
+    SymbolString& output, size_t* usedLength) const;
-
-  /** the value unit. */
-  const string m_unit;
-
-  /** the data type definition. */
-  DataType* m_dataType;
 
   /** the message part in which the field is stored. */
   const PartType m_partType;
 
+  /** the data type definition. */
+  const DataType* m_dataType;
+
   /** the number of symbols in the message part in which the field is stored. */
   const size_t m_length;
 };
@@ -407,17 +464,15 @@ class ValueListDataField : public SingleDataField {
   /**
    * Constructs a new instance.
    * @param name the field name.
-   * @param comment the field comment.
+   * @param attributes the additional named attributes.
-   * @param unit the value unit.
    * @param dataType the data type definition.
    * @param partType the message part in which the field is stored.
    * @param length the number of symbols in the message part in which the field is stored.
    * @param values the value=text assignments.
    */
-  ValueListDataField(const string name, const string comment,
+  ValueListDataField(const string name, const map<string, string>& attributes, const DataType* dataType,
-    const string unit, NumberDataType* dataType, const PartType partType,
+    const PartType partType, const size_t length, const map<unsigned int, string> values)
-    const size_t length, const map<unsigned int, string> values)
+    : SingleDataField(name, attributes, dataType, partType, length),
-    : SingleDataField(name, comment, unit, dataType, partType, length),
     m_values(values) {}
 
   /**
@@ -426,31 +481,29 @@ class ValueListDataField : public SingleDataField {
   virtual ~ValueListDataField() {}
 
   // @copydoc
-  ValueListDataField* clone() override;
+  const ValueListDataField* clone() const override;
 
   // @copydoc
-  result_t derive(string name, string comment,
+  result_t derive(const string name, map<string, string> attributes, const PartType partType,
-      string unit, const PartType partType, int divisor,
+      int divisor, map<unsigned int, string> values, vector<const SingleDataField*>& fields) const override;
-      map<unsigned int, string> values,
-      vector<SingleDataField*>& fields) override;
 
   // @copydoc
-  void dump(ostream& output) override;
+  void dump(ostream& output) const override;
 
 
  protected:
   // @copydoc
-  result_t readSymbols(SymbolString& input, const size_t offset,
+  result_t readSymbols(const SymbolString& input, const size_t offset,
-      ostringstream& output, OutputFormat outputFormat) override;
+    ostringstream& output, OutputFormat outputFormat) const override;
 
   // @copydoc
   result_t writeSymbols(istringstream& input, const size_t offset,
-      SymbolString& output, size_t* usedLength) override;
+    SymbolString& output, size_t* usedLength) const override;
 
 
  private:
   /** the value=text assignments. */
-  map<unsigned int, string> m_values;
+  const map<unsigned int, string> m_values;
 };
 
 
@@ -462,18 +515,16 @@ class ConstantDataField : public SingleDataField {
   /**
    * Constructs a new instance.
    * @param name the field name.
-   * @param comment the field comment.
+   * @param attributes the additional named attributes.
-   * @param unit the value unit.
    * @param dataType the data type definition.
    * @param partType the message part in which the field is stored.
    * @param length the number of symbols in the message part in which the field is stored.
    * @param value the constant value.
    * @param verify whether to verify the read value against the constant value.
    */
-  ConstantDataField(const string name, const string comment,
+  ConstantDataField(const string name, const map<string, string>& attributes, const DataType* dataType,
-    const string unit, DataType* dataType, const PartType partType,
+    const PartType partType, const size_t length, const string value, const bool verify)
-    const size_t length, const string value, const bool verify)
+    : SingleDataField(name, attributes, dataType, partType, length),
-    : SingleDataField(name, comment, unit, dataType, partType, length),
     m_value(value), m_verify(verify) {}
 
   /**
@@ -482,26 +533,24 @@ class ConstantDataField : public SingleDataField {
   virtual ~ConstantDataField() {}
 
   // @copydoc
-  ConstantDataField* clone() override;
+  const ConstantDataField* clone() const override;
 
   // @copydoc
-  result_t derive(string name, string comment,
+  result_t derive(const string name, map<string, string> attributes, const PartType partType,
-      string unit, const PartType partType, int divisor,
+    int divisor, map<unsigned int, string> values, vector<const SingleDataField*>& fields) const override;
-      map<unsigned int, string> values,
-      vector<SingleDataField*>& fields) override;
 
   // @copydoc
-  void dump(ostream& output) override;
+  void dump(ostream& output) const override;
 
 
  protected:
   // @copydoc
-  result_t readSymbols(SymbolString& input, const size_t offset,
+  result_t readSymbols(const SymbolString& input, const size_t offset,
-      ostringstream& output, OutputFormat outputFormat) override;
+    ostringstream& output, OutputFormat outputFormat) const override;
 
   // @copydoc
   result_t writeSymbols(istringstream& input, const size_t offset,
-      SymbolString& output, size_t* usedLength) override;
+    SymbolString& output, size_t* usedLength) const override;
 
 
  private:
@@ -533,16 +582,13 @@ class DataFieldSet : public DataField {
   /**
    * Constructs a new instance.
    * @param name the field name.
-   * @param comment the field comment.
    * @param fields the @a vector of @a SingleDataField instances part of this set.
    */
-  DataFieldSet(const string name, const string comment,
+  DataFieldSet(const string name, const vector<const SingleDataField*> fields)
-      const vector<SingleDataField*> fields)
+    : DataField(name), m_fields(fields) {
-    : DataField(name, comment), m_fields(fields) {
     bool uniqueNames = true;
     map<string, string> names;
-    for (vector<SingleDataField*>::const_iterator it = fields.begin(); it != fields.end(); it++) {
+    for (auto field : fields) {
-      SingleDataField* field = *it;
       if (field->isIgnored()) {
         continue;
       }
@@ -562,31 +608,29 @@ class DataFieldSet : public DataField {
   virtual ~DataFieldSet();
 
   // @copydoc
-  DataFieldSet* clone() override;
+  const DataFieldSet* clone() const override;
 
   // @copydoc
-  size_t getLength(PartType partType, size_t maxLength = MAX_LEN) override;
+  size_t getLength(PartType partType, size_t maxLength = MAX_LEN) const override;
 
   // @copydoc
-  string getName(ssize_t fieldIndex = -1) override;
+  string getName(const ssize_t fieldIndex = -1) const override;
 
   // @copydoc
-  result_t derive(string name, string comment,
+  result_t derive(const string name, map<string, string> attributes, const PartType partType,
-      string unit, const PartType partType,
+    int divisor, map<unsigned int, string> values, vector<const SingleDataField*>& fields) const override;
-      int divisor, map<unsigned int, string> values,
-      vector<SingleDataField*>& fields) override;
 
   /**
    * Returns the @a SingleDataField at the specified index.
    * @param index the index of the @a SingleDataField to return.
    * @return the @a SingleDataField at the specified index, or NULL.
    */
-  SingleDataField* operator[](const size_t index) {
+  /*SingleDataField* operator[](const size_t index) {
     if (index >= m_fields.size()) {
       return NULL;
     }
     return m_fields[index];
-  }
+  }*/
 
   /**
    * Returns the @a SingleDataField at the specified index.
@@ -607,23 +651,23 @@ class DataFieldSet : public DataField {
   size_t size() const { return m_fields.size(); }
 
   // @copydoc
-  bool hasField(const char* fieldName, bool numeric) override;
+  bool hasField(const char* fieldName, bool numeric) const override;
 
   // @copydoc
-  void dump(ostream& output) override;
+  void dump(ostream& output) const override;
 
   // @copydoc
-  result_t read(SymbolString& data, size_t offset,
+  result_t read(const SymbolString& data, size_t offset,
-      unsigned int& output, const char* fieldName = NULL, ssize_t fieldIndex = -1) override;
+    unsigned int& output, const char* fieldName = NULL, ssize_t fieldIndex = -1) const override;
 
   // @copydoc
-  result_t read(SymbolString& data, size_t offset,
+  result_t read(const SymbolString& data, size_t offset,
-      ostringstream& output, OutputFormat outputFormat, ssize_t outputIndex = -1,
+    ostringstream& output, OutputFormat outputFormat, ssize_t outputIndex = -1,
-      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) override;
+    bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) const override;
 
   // @copydoc
   result_t write(istringstream& input, SymbolString& data,
-      size_t offset, char separator = UI_FIELD_SEPARATOR, size_t* length = NULL) override;
+    size_t offset, char separator = UI_FIELD_SEPARATOR, size_t* length = NULL) const override;
 
 
  private:
@@ -631,7 +675,7 @@ class DataFieldSet : public DataField {
   static DataFieldSet* s_identFields;
 
   /** the @a vector of @a SingleDataField instances part of this set. */
-  vector<SingleDataField*> m_fields;
+  const vector<const SingleDataField*> m_fields;
 
   /** whether all fields have a unique name. */
   bool m_uniqueNames;
@@ -674,14 +718,14 @@ class DataFieldTemplates : public MappedFileReader {
    * @return @a RESULT_OK on success, or an error code.
    * Note: the caller may not free the added instance on success.
    */
-  result_t add(DataField* field, string name = "", bool replace = false);
+  result_t add(const DataField* field, string name = "", bool replace = false);
 
   // @copydoc
-  result_t getFieldMap(vector<string>& row, string& errorDescription) override;
+  result_t getFieldMap(vector<string>& row, string& errorDescription) const override;
 
   // @copydoc
   result_t addFromFile(map<string, string>& row, vector< map<string, string> >& subRows,
-      string& errorDescription, const string filename, unsigned int lineNo) override;
+    string& errorDescription, const string filename, unsigned int lineNo) override;
 
   /**
    * Gets the template @a DataField instance with the specified name.
@@ -689,12 +733,12 @@ class DataFieldTemplates : public MappedFileReader {
    * @return the template @a DataField instance, or NULL.
    * Note: the caller may not free the returned instance.
    */
-  DataField* get(string name);
+  const DataField* get(string name) const;
 
 
  private:
   /** the known template @a DataField instances by name. */
-  map<string, DataField*> m_fieldsByName;
+  map<string, const DataField*> m_fieldsByName;
 };
 
 }  // namespace ebusd

src/lib/ebus/datatype.cpp

@@ -58,14 +58,14 @@ bool DataType::dump(ostream& output, const size_t length, const bool appendSepar
 }
 
 
-result_t StringDataType::readRawValue(SymbolString& input, const size_t offset,
+result_t StringDataType::readRawValue(const SymbolString& input, const size_t offset,
-    const size_t length, unsigned int& value) {
+    const size_t length, unsigned int& value) const {
   return RESULT_EMPTY;
 }
 
-result_t StringDataType::readSymbols(SymbolString& input,
+result_t StringDataType::readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) {
+    ostringstream& output, OutputFormat outputFormat) const {
   size_t start = 0, count = length;
   int incr = 1;
   symbol_t symbol;
@@ -116,7 +116,7 @@ result_t StringDataType::readSymbols(SymbolString& input,
 
 result_t StringDataType::writeSymbols(istringstream& input,
     size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) {
+    SymbolString& output, size_t* usedLength) const {
   size_t start = 0, count = length;
   bool remainder = count == REMAIN_LEN && hasFlag(ADJ);
   int incr = 1;
@@ -196,14 +196,14 @@ result_t StringDataType::writeSymbols(istringstream& input,
 }
 
 
-result_t DateTimeDataType::readRawValue(SymbolString& input, const size_t offset,
+result_t DateTimeDataType::readRawValue(const SymbolString& input, const size_t offset,
-    const size_t length, unsigned int& value) {
+    const size_t length, unsigned int& value) const {
   return RESULT_EMPTY;
 }
 
-result_t DateTimeDataType::readSymbols(SymbolString& input,
+result_t DateTimeDataType::readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) {
+    ostringstream& output, OutputFormat outputFormat) const {
   size_t start = 0, count = length;
   int incr = 1;
   symbol_t symbol, last = 0, hour = 0;
@@ -335,7 +335,7 @@ result_t DateTimeDataType::readSymbols(SymbolString& input,
 
 result_t DateTimeDataType::writeSymbols(istringstream& input,
     size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) {
+    SymbolString& output, size_t* usedLength) const {
   size_t start = 0, count = length;
   bool remainder = count == REMAIN_LEN && hasFlag(ADJ);
   int incr = 1;
@@ -527,7 +527,7 @@ bool NumberDataType::dump(ostream& output, size_t length, const bool appendSepar
   return false;
 }
 
-result_t NumberDataType::derive(int divisor, size_t bitCount, NumberDataType* &derived) {
+result_t NumberDataType::derive(int divisor, size_t bitCount, const NumberDataType* &derived) const {
   if (divisor == 0) {
     divisor = 1;
   }
@@ -570,19 +570,18 @@ result_t NumberDataType::derive(int divisor, size_t bitCount, NumberDataType* &d
   }
   if (m_bitCount < 8) {
     derived = new NumberDataType(m_id, bitCount, m_flags, m_replacement,
-      m_firstBit, divisor);
+      m_firstBit, divisor, m_baseType ? m_baseType : this);
   } else {
     derived = new NumberDataType(m_id, bitCount, m_flags, m_replacement,
-      m_minValue, m_maxValue, divisor);
+      m_minValue, m_maxValue, divisor, m_baseType ? m_baseType : this);
   }
-  derived->m_baseType = m_baseType ? m_baseType : this;
   DataTypeList::getInstance()->addCleanup(derived);
   return RESULT_OK;
 }
 
-result_t NumberDataType::readRawValue(SymbolString& input,
+result_t NumberDataType::readRawValue(const SymbolString& input,
     size_t offset, const size_t length,
-    unsigned int& value) {
+    unsigned int& value) const {
   size_t start = 0, count = length;
   int incr = 1;
   symbol_t symbol;
@@ -629,9 +628,9 @@ result_t NumberDataType::readRawValue(SymbolString& input,
   return RESULT_OK;
 }
 
-result_t NumberDataType::readSymbols(SymbolString& input,
+result_t NumberDataType::readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) {
+    ostringstream& output, OutputFormat outputFormat) const {
   unsigned int value = 0;
   int signedValue;
 
@@ -743,7 +742,7 @@ result_t NumberDataType::readSymbols(SymbolString& input,
 
 result_t NumberDataType::writeRawValue(unsigned int value,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) {
+    SymbolString& output, size_t* usedLength) const {
   size_t start = 0, count = length;
   int incr = 1;
   symbol_t symbol;
@@ -789,7 +788,7 @@ result_t NumberDataType::writeRawValue(unsigned int value,
 
 result_t NumberDataType::writeSymbols(istringstream& input,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) {
+    SymbolString& output, size_t* usedLength) const {
   unsigned int value;
 
   const char* str = input.str().c_str();
@@ -906,8 +905,8 @@ bool DataTypeList::s_contrib_initialized = libebus_contrib_register();
 DataTypeList::DataTypeList() {
   add(new StringDataType("STR", MAX_LEN*8, ADJ, ' '));  // >= 1 byte character string filled up with space
   // unsigned decimal in BCD, 0000 - 9999 (fixed length)
-  add(new NumberDataType("PIN", 16, FIX|BCD|REV, 0xffff, 0, 0x9999, 1));
+  add(new NumberDataType("PIN", 16, FIX|BCD|REV, 0xffff, 0, 0x9999, 1, NULL));
-  add(new NumberDataType("UCH", 8, 0, 0xff, 0, 0xfe, 1));  // unsigned integer, 0 - 254
+  add(new NumberDataType("UCH", 8, 0, 0xff, 0, 0xfe, 1, NULL));  // unsigned integer, 0 - 254
   add(new StringDataType("IGN", MAX_LEN*8, IGN|ADJ, 0));  // >= 1 byte ignored data
   // >= 1 byte character string filled up with 0x00 (null terminated string)
   add(new StringDataType("NTS", MAX_LEN*8, ADJ, 0));
@@ -945,56 +944,56 @@ DataTypeList::DataTypeList() {
   add(new DateTimeDataType("TTH", 6, 0, 0, false, true, 30));
   // truncated time (only multiple of 15 minutes), 00:00 - 24:00 (minutes div 15 + hour * 4 as integer)
   add(new DateTimeDataType("TTQ", 7, 0, 0, false, true, 15));
-  add(new NumberDataType("BDY", 8, DAY, 0x07, 0, 6, 1));  // weekday, "Mon" - "Sun" (0x00 - 0x06) [eBUS type]
+  add(new NumberDataType("BDY", 8, DAY, 0x07, 0, 6, 1, NULL));  // weekday, "Mon" - "Sun" (0x00 - 0x06) [eBUS type]
-  add(new NumberDataType("HDY", 8, DAY, 0x00, 1, 7, 1));  // weekday, "Mon" - "Sun" (0x01 - 0x07) [Vaillant type]
+  add(new NumberDataType("HDY", 8, DAY, 0x00, 1, 7, 1, NULL));  // weekday, "Mon" - "Sun" (0x01 - 0x07) [Vaillant type]
-  add(new NumberDataType("BCD", 8, BCD, 0xff, 0, 99, 1));  // unsigned decimal in BCD, 0 - 99
+  add(new NumberDataType("BCD", 8, BCD, 0xff, 0, 99, 1, NULL));  // unsigned decimal in BCD, 0 - 99
-  add(new NumberDataType("BCD", 16, BCD, 0xffff, 0, 9999, 1));  // unsigned decimal in BCD, 0 - 9999
+  add(new NumberDataType("BCD", 16, BCD, 0xffff, 0, 9999, 1, NULL));  // unsigned decimal in BCD, 0 - 9999
-  add(new NumberDataType("BCD", 24, BCD, 0xffffff, 0, 999999, 1));  // unsigned decimal in BCD, 0 - 999999
+  add(new NumberDataType("BCD", 24, BCD, 0xffffff, 0, 999999, 1, NULL));  // unsigned decimal in BCD, 0 - 999999
-  add(new NumberDataType("BCD", 32, BCD, 0xffffffff, 0, 99999999, 1));  // unsigned decimal in BCD, 0 - 99999999
+  add(new NumberDataType("BCD", 32, BCD, 0xffffffff, 0, 99999999, 1, NULL));  // unsigned decimal in BCD, 0 - 99999999
-  add(new NumberDataType("HCD", 32, HCD|BCD|REQ, 0, 0, 99999999, 1));  // unsigned decimal in HCD, 0 - 99999999
+  add(new NumberDataType("HCD", 32, HCD|BCD|REQ, 0, 0, 99999999, 1, NULL));  // unsigned decimal in HCD, 0 - 99999999
-  add(new NumberDataType("HCD", 8, HCD|BCD|REQ, 0, 0, 99, 1));  // unsigned decimal in HCD, 0 - 99
+  add(new NumberDataType("HCD", 8, HCD|BCD|REQ, 0, 0, 99, 1, NULL));  // unsigned decimal in HCD, 0 - 99
-  add(new NumberDataType("HCD", 16, HCD|BCD|REQ, 0, 0, 9999, 1));  // unsigned decimal in HCD, 0 - 9999
+  add(new NumberDataType("HCD", 16, HCD|BCD|REQ, 0, 0, 9999, 1, NULL));  // unsigned decimal in HCD, 0 - 9999
-  add(new NumberDataType("HCD", 24, HCD|BCD|REQ, 0, 0, 999999, 1));  // unsigned decimal in HCD, 0 - 999999
+  add(new NumberDataType("HCD", 24, HCD|BCD|REQ, 0, 0, 999999, 1, NULL));  // unsigned decimal in HCD, 0 - 999999
-  add(new NumberDataType("SCH", 8, SIG, 0x80, 0x81, 0x7f, 1));  // signed integer, -127 - +127
+  add(new NumberDataType("SCH", 8, SIG, 0x80, 0x81, 0x7f, 1, NULL));  // signed integer, -127 - +127
-  add(new NumberDataType("D1B", 8, SIG, 0x80, 0x81, 0x7f, 1));  // signed integer, -127 - +127
+  add(new NumberDataType("D1B", 8, SIG, 0x80, 0x81, 0x7f, 1, NULL));  // signed integer, -127 - +127
   // unsigned number (fraction 1/2), 0 - 100 (0x00 - 0xc8, replacement 0xff)
-  add(new NumberDataType("D1C", 8, 0, 0xff, 0x00, 0xc8, 2));
+  add(new NumberDataType("D1C", 8, 0, 0xff, 0x00, 0xc8, 2, NULL));
   // signed number (fraction 1/256), -127.99 - +127.99
-  add(new NumberDataType("D2B", 16, SIG, 0x8000, 0x8001, 0x7fff, 256));
+  add(new NumberDataType("D2B", 16, SIG, 0x8000, 0x8001, 0x7fff, 256, NULL));
   // signed number (fraction 1/16), -2047.9 - +2047.9
-  add(new NumberDataType("D2C", 16, SIG, 0x8000, 0x8001, 0x7fff, 16));
+  add(new NumberDataType("D2C", 16, SIG, 0x8000, 0x8001, 0x7fff, 16, NULL));
   // signed number (fraction 1/1000), -32.767 - +32.767, little endian
-  add(new NumberDataType("FLT", 16, SIG, 0x8000, 0x8001, 0x7fff, 1000));
+  add(new NumberDataType("FLT", 16, SIG, 0x8000, 0x8001, 0x7fff, 1000, NULL));
   // signed number (fraction 1/1000), -32.767 - +32.767, big endian
-  add(new NumberDataType("FLR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1000));
+  add(new NumberDataType("FLR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1000, NULL));
   // signed number (IEEE 754 binary32: 1 bit sign, 8 bits exponent, 23 bits significand), little endian
-  add(new NumberDataType("EXP", 32, SIG|EXP, 0x7f800000, 0x00000000, 0xffffffff, 1));
+  add(new NumberDataType("EXP", 32, SIG|EXP, 0x7f800000, 0x00000000, 0xffffffff, 1, NULL));
   // signed number (IEEE 754 binary32: 1 bit sign, 8 bits exponent, 23 bits significand), big endian
-  add(new NumberDataType("EXR", 32, SIG|EXP|REV, 0x7f800000, 0x00000000, 0xffffffff, 1));
+  add(new NumberDataType("EXR", 32, SIG|EXP|REV, 0x7f800000, 0x00000000, 0xffffffff, 1, NULL));
   // unsigned integer, 0 - 65534, little endian
-  add(new NumberDataType("UIN", 16, 0, 0xffff, 0, 0xfffe, 1));
+  add(new NumberDataType("UIN", 16, 0, 0xffff, 0, 0xfffe, 1, NULL));
   // unsigned integer, 0 - 65534, big endian
-  add(new NumberDataType("UIR", 16, REV, 0xffff, 0, 0xfffe, 1));
+  add(new NumberDataType("UIR", 16, REV, 0xffff, 0, 0xfffe, 1, NULL));
   // signed integer, -32767 - +32767, little endian
-  add(new NumberDataType("SIN", 16, SIG, 0x8000, 0x8001, 0x7fff, 1));
+  add(new NumberDataType("SIN", 16, SIG, 0x8000, 0x8001, 0x7fff, 1, NULL));
   // signed integer, -32767 - +32767, big endian
-  add(new NumberDataType("SIR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1));
+  add(new NumberDataType("SIR", 16, SIG|REV, 0x8000, 0x8001, 0x7fff, 1, NULL));
   // unsigned 3 bytes int, 0 - 16777214, little endian
-  add(new NumberDataType("U3N", 24, 0, 0xffffff, 0, 0xfffffe, 1));
+  add(new NumberDataType("U3N", 24, 0, 0xffffff, 0, 0xfffffe, 1, NULL));
   // unsigned 3 bytes int, 0 - 16777214, big endian
-  add(new NumberDataType("U3R", 24, REV, 0xffffff, 0, 0xfffffe, 1));
+  add(new NumberDataType("U3R", 24, REV, 0xffffff, 0, 0xfffffe, 1, NULL));
   // signed 3 bytes int, -8388607 - +8388607, little endian
-  add(new NumberDataType("S3N", 24, SIG, 0x800000, 0x800001, 0xffffff, 1));
+  add(new NumberDataType("S3N", 24, SIG, 0x800000, 0x800001, 0xffffff, 1, NULL));
   // signed 3 bytes int, -8388607 - +8388607, big endian
-  add(new NumberDataType("S3R", 24, SIG|REV, 0x800000, 0x800001, 0xffffff, 1));
+  add(new NumberDataType("S3R", 24, SIG|REV, 0x800000, 0x800001, 0xffffff, 1, NULL));
   // unsigned integer, 0 - 4294967294, little endian
-  add(new NumberDataType("ULG", 32, 0, 0xffffffff, 0, 0xfffffffe, 1));
+  add(new NumberDataType("ULG", 32, 0, 0xffffffff, 0, 0xfffffffe, 1, NULL));
   // unsigned integer, 0 - 4294967294, big endian
-  add(new NumberDataType("ULR", 32, REV, 0xffffffff, 0, 0xfffffffe, 1));
+  add(new NumberDataType("ULR", 32, REV, 0xffffffff, 0, 0xfffffffe, 1, NULL));
   // signed integer, -2147483647 - +2147483647, little endian
-  add(new NumberDataType("SLG", 32, SIG, 0x80000000, 0x80000001, 0xffffffff, 1));
+  add(new NumberDataType("SLG", 32, SIG, 0x80000000, 0x80000001, 0xffffffff, 1, NULL));
   // signed integer, -2147483647 - +2147483647, big endian
-  add(new NumberDataType("SLR", 32, SIG|REV, 0x80000000, 0x80000001, 0xffffffff, 1));
+  add(new NumberDataType("SLR", 32, SIG|REV, 0x80000000, 0x80000001, 0xffffffff, 1, NULL));
   add(new NumberDataType("BI0", 7, ADJ|REQ, 0, 0, 1));  // bit 0 (up to 7 bits until bit 6)
   add(new NumberDataType("BI1", 7, ADJ|REQ, 0, 1, 1));  // bit 1 (up to 7 bits until bit 7)
   add(new NumberDataType("BI2", 6, ADJ|REQ, 0, 2, 1));  // bit 2 (up to 6 bits until bit 7)
@@ -1010,21 +1009,20 @@ DataTypeList* DataTypeList::getInstance() {
 }
 
 void DataTypeList::clear() {
-  for (list<DataType*>::iterator it = m_cleanupTypes.begin(); it != m_cleanupTypes.end(); it++) {
+  for (auto& it : m_cleanupTypes) {
-    delete *it;
+    delete it;
   }
   m_cleanupTypes.clear();
   m_typesByIdLength.clear();
   m_typesById.clear();
 }
 
-result_t DataTypeList::add(DataType* dataType) {
+result_t DataTypeList::add(const DataType* dataType) {
   if (!dataType->isAdjustableLength()) {
     ostringstream str;
     size_t bitCount = dataType->getBitCount();
     str << dataType->getId() << LENGTH_SEPARATOR << static_cast<unsigned>(bitCount >= 8?bitCount/8:bitCount);
-    map<string, DataType*>::iterator it = m_typesByIdLength.find(str.str());
+    if (m_typesByIdLength.find(str.str()) != m_typesByIdLength.end()) {
-    if (it != m_typesByIdLength.end()) {
       return RESULT_ERR_DUPLICATE_NAME;  // duplicate key
     }
     m_typesByIdLength[str.str()] = dataType;
@@ -1040,20 +1038,23 @@ result_t DataTypeList::add(DataType* dataType) {
   return RESULT_OK;
 }
 
-DataType* DataTypeList::get(const string id, const size_t length) {
+const DataType* DataTypeList::get(const string id, const size_t length) const {
-  DataType* dataType = NULL;
   if (length > 0) {
     ostringstream str;
     str << id << LENGTH_SEPARATOR << static_cast<unsigned>(length);
-    dataType = m_typesByIdLength[str.str()];
+    auto it = m_typesByIdLength.find(str.str());
-  }
+    if (it != m_typesByIdLength.end()) {
-  if (!dataType) {
+      return it->second;
-    dataType = m_typesById[id];
-    if (dataType && length > 0 && !dataType->isAdjustableLength()) {
-      return NULL;
     }
   }
-  return dataType;
+  auto it = m_typesById.find(id);
+  if (it == m_typesById.end()) {
+    return NULL;
+  }
+  if (length > 0 && !it->second->isAdjustableLength()) {
+    return NULL;
+  }
+  return it->second;
 }
 
 }  // namespace ebusd

src/lib/ebus/datatype.h

@@ -100,6 +100,9 @@ typedef int OutputFormat;
 /** bit flag for @a OutputFormat: short format (only name and value, no indentation). */
 #define OF_SHORT 0x20
 
+/** bit flag for @a OutputFormat: include all attributes. */
+#define OF_ALL_ATTRS 0x40
+
 /** the message part in which a data field is stored. */
 enum PartType {
   pt_any,          //!< stored in any data (master or slave)
@@ -225,9 +228,9 @@ class DataType {
    * @param value the variable in which to store the numeric raw value.
    * @return @a RESULT_OK on success, or an error code.
    */
-  virtual result_t readRawValue(SymbolString& input,
+  virtual result_t readRawValue(const SymbolString& input,
     const size_t offset, const size_t length,
-    unsigned int& value) = 0;
+    unsigned int& value) const = 0;
 
   /**
    * Internal method for reading the field from a @a SymbolString.
@@ -238,9 +241,9 @@ class DataType {
    * @param outputFormat the @a OutputFormat options to use.
    * @return @a RESULT_OK on success, or an error code.
    */
-  virtual result_t readSymbols(SymbolString& input,
+  virtual result_t readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) = 0;
+    ostringstream& output, OutputFormat outputFormat) const = 0;
 
   /**
    * Internal method for writing the field to a @a SymbolString.
@@ -253,7 +256,7 @@ class DataType {
    */
   virtual result_t writeSymbols(istringstream& input,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) = 0;
+    SymbolString& output, size_t* usedLength) const = 0;
 
 
  protected:
@@ -295,19 +298,19 @@ class StringDataType : public DataType {
   virtual ~StringDataType() {}
 
   // @copydoc
-  result_t readRawValue(SymbolString& input,
+  result_t readRawValue(const SymbolString& input,
     const size_t offset, const size_t length,
-    unsigned int& value) override;
+    unsigned int& value) const override;
 
   // @copydoc
-  result_t readSymbols(SymbolString& input,
+  result_t readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) override;
+    ostringstream& output, OutputFormat outputFormat) const override;
 
   // @copydoc
   result_t writeSymbols(istringstream& input,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) override;
+    SymbolString& output, size_t* usedLength) const override;
 
 
  private:
@@ -357,19 +360,19 @@ class DateTimeDataType : public DataType {
   int16_t getResolution() const { return m_resolution; }
 
   // @copydoc
-  result_t readRawValue(SymbolString& input,
+  result_t readRawValue(const SymbolString& input,
     const size_t offset, const size_t length,
-    unsigned int& value) override;
+    unsigned int& value) const override;
 
   // @copydoc
-  result_t readSymbols(SymbolString& input,
+  result_t readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) override;
+    ostringstream& output, OutputFormat outputFormat) const override;
 
   // @copydoc
   result_t writeSymbols(istringstream& input,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) override;
+    SymbolString& output, size_t* usedLength) const override;
 
 
  private:
@@ -398,11 +401,13 @@ class NumberDataType : public DataType {
    * @param minValue the minimum raw value.
    * @param maxValue the maximum raw value.
    * @param divisor the divisor (negative for reciprocal).
+   * @param baseType the base @a NumberDataType for derived instances, or NULL.
    */
   NumberDataType(const string id, const size_t bitCount, const uint16_t flags, const unsigned int replacement,
-      const unsigned int minValue, const unsigned int maxValue, const int divisor)
+      const unsigned int minValue, const unsigned int maxValue, const int divisor,
+      const NumberDataType* baseType)
     : DataType(id, bitCount, flags|NUM, replacement), m_minValue(minValue), m_maxValue(maxValue), m_divisor(divisor),
-      m_precision(calcPrecision(divisor)), m_firstBit(0), m_baseType(NULL) {}
+      m_precision(calcPrecision(divisor)), m_firstBit(0), m_baseType(baseType) {}
 
   /**
    * Constructs a new instance for less than 8 bits.
@@ -412,11 +417,12 @@ class NumberDataType : public DataType {
    * @param replacement the replacement value (no replacement if zero).
    * @param firstBit the offset to the first bit.
    * @param divisor the divisor (negative for reciprocal).
+   * @param baseType the base @a NumberDataType for derived instances, or NULL.
    */
   NumberDataType(const string id, const size_t bitCount, const uint16_t flags, const unsigned int replacement,
-      const int16_t firstBit, const int divisor)
+      const int16_t firstBit, const int divisor, const NumberDataType* baseType = NULL)
     : DataType(id, bitCount, flags|NUM, replacement), m_minValue(0), m_maxValue((1 << bitCount)-1), m_divisor(divisor),
-      m_precision(0), m_firstBit(firstBit), m_baseType(NULL) {}
+      m_precision(0), m_firstBit(firstBit), m_baseType(baseType) {}
 
   /**
    * Destructor.
@@ -444,7 +450,7 @@ class NumberDataType : public DataType {
    * not necessary.
    * @return @a RESULT_OK on success, or an error code.
    */
-  virtual result_t derive(int divisor, size_t bitCount, NumberDataType* &derived);
+  virtual result_t derive(int divisor, size_t bitCount, const NumberDataType* &derived) const;
 
   /**
    * @return the minimum raw value.
@@ -472,14 +478,14 @@ class NumberDataType : public DataType {
   int16_t getFirstBit() const { return m_firstBit; }
 
   // @copydoc
-  result_t readRawValue(SymbolString& input,
+  result_t readRawValue(const SymbolString& input,
     const size_t offset, const size_t length,
-    unsigned int& value) override;
+    unsigned int& value) const override;
 
   // @copydoc
-  result_t readSymbols(SymbolString& input,
+  result_t readSymbols(const SymbolString& input,
     const size_t offset, const size_t length,
-    ostringstream& output, OutputFormat outputFormat) override;
+    ostringstream& output, OutputFormat outputFormat) const override;
 
   /**
    * Internal method for writing the numeric raw value to a @a SymbolString.
@@ -493,12 +499,12 @@ class NumberDataType : public DataType {
    */
   result_t writeRawValue(unsigned int value,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength = NULL);
+    SymbolString& output, size_t* usedLength = NULL) const;
 
   // @copydoc
   result_t writeSymbols(istringstream& input,
     const size_t offset, const size_t length,
-    SymbolString& output, size_t* usedLength) override;
+    SymbolString& output, size_t* usedLength) const override;
 
 
  private:
@@ -518,7 +524,7 @@ class NumberDataType : public DataType {
   const int16_t m_firstBit;
 
   /** the base @a NumberDataType for derived instances. */
-  NumberDataType* m_baseType;
+  const NumberDataType* m_baseType;
 };
 
 
@@ -556,13 +562,13 @@ class DataTypeList {
    * @return @a RESULT_OK on success, or an error code.
    * Note: the caller may not free the added instance on success.
    */
-  result_t add(DataType* dataType);
+  result_t add(const DataType* dataType);
 
   /**
    * Adds a @a DataType instance for later cleanup.
    * @param dataType the @a DataType instance to add.
    */
-  void addCleanup(DataType* dataType) { m_cleanupTypes.push_back(dataType); }
+  void addCleanup(const DataType* dataType) { m_cleanupTypes.push_back(dataType); }
 
   /**
    * Gets the @a DataType instance with the specified ID.
@@ -571,30 +577,30 @@ class DataTypeList {
    * @return the @a DataType instance, or NULL if not available.
    * Note: the caller may not free the instance.
    */
-  DataType* get(const string id, const size_t length = 0);
+  const DataType* get(const string id, const size_t length = 0) const;
 
   /**
    * Returns an iterator pointing to the first ID/@a DataType pair.
    * @return an iterator pointing to the first ID/@a DataType pair.
    */
-  map<string, DataType*>::const_iterator begin() const { return m_typesById.begin(); }
+  map<string, const DataType*>::const_iterator begin() const { return m_typesById.begin(); }
 
   /**
    * Returns an iterator pointing one past the last ID/@a DataType pair.
    * @return an iterator pointing one past the last ID/@a DataType pair.
    */
-  map<string, DataType*>::const_iterator end() const { return m_typesById.end(); }
+  map<string, const DataType*>::const_iterator end() const { return m_typesById.end(); }
 
  private:
   /** the known @a DataType instances by ID only. */
-  map<string, DataType*> m_typesById;
+  map<string, const DataType*> m_typesById;
 
   /** the known @a DataType instances by ID and length (i.e. "ID:BITS").
    * Note: adjustable length types are stored by ID only. */
-  map<string, DataType*> m_typesByIdLength;
+  map<string, const DataType*> m_typesByIdLength;
 
   /** the @a DataType instances to cleanup. */
-  list<DataType*> m_cleanupTypes;
+  list<const DataType*> m_cleanupTypes;
 
   /** the singleton instance. */
   static DataTypeList s_instance;

src/lib/ebus/filereader.cpp

@@ -75,11 +75,14 @@ result_t FileReader::readFromFile(const string filename, string& errorDescriptio
 result_t FileReader::readLineFromStream(istream& stream, string& errorDescription,
     const string filename, unsigned int& lineNo, vector<string>& row, bool verbose,
     size_t* hash, size_t* size) {
+  result_t result;
   if (!splitFields(stream, row, lineNo, hash, size)) {
-    return RESULT_ERR_EOF;
+    errorDescription = "blank line";
+    result = RESULT_ERR_EOF;
+  } else {
+    errorDescription = "";
+    result = addFromFile(row, errorDescription, filename, lineNo);
   }
-  errorDescription = "";
-  result_t result = addFromFile(row, errorDescription, filename, lineNo);
   if (result != RESULT_OK) {
     if (!verbose) {
       ostringstream error;
@@ -134,6 +137,7 @@ bool FileReader::splitFields(istream& ifs, vector<string>& row, unsigned int& li
       *size += length + 1;  // normalized with trailing endl
     }
     if (hash) {
+      // TODO ensure 32 bit machine produces same result
       *hash ^= (hashFunction(line) << 1) ^ (length << (7 * (lineNo % 5)));
     }
     if (!quotedText && (length == 0 || line[0] == '#' || (line.length() > 1 && line[0] == '/' && line[1] == '/'))) {

src/lib/ebus/filereader.h

@@ -185,7 +185,7 @@ class MappedFileReader : public FileReader {
    * @return true if the minimum parts were extracted, false otherwise.
    */
   virtual bool extractDefaultsFromFilename(string filename, map<string, string>& defaults,
-      symbol_t* destAddress = NULL, unsigned int* software = NULL, unsigned int* hardware = NULL) {
+      symbol_t* destAddress = NULL, unsigned int* software = NULL, unsigned int* hardware = NULL) const {
     return false;
   }
 
@@ -199,7 +199,7 @@ class MappedFileReader : public FileReader {
    * @param errorDescription a string in which to store the error description in case of error.
    * @return @a RESULT_OK on success, or an error code.
    */
-  virtual result_t getFieldMap(vector<string>& row, string& errorDescription) = 0;
+  virtual result_t getFieldMap(vector<string>& row, string& errorDescription) const = 0;
 
   /**
    * Add a default row that was read from a file.
@@ -231,14 +231,14 @@ class MappedFileReader : public FileReader {
   /**
    * @return a reference to all previously extracted default values by type and field name.
    */
-  virtual map<string, map<string, string> >& getDefaults() {
+  map<string, map<string, string> >& getDefaults() {
     return m_lastDefaults;
   }
 
   /**
    * @return a reference to all previously extracted sub default values by type and field name.
    */
-  virtual map<string, vector< map<string, string> > >& getSubDefaults() {
+  map<string, vector< map<string, string> > >& getSubDefaults() {
     return m_lastSubDefaults;
   }
 

src/lib/ebus/message.cpp

@@ -161,20 +161,20 @@ string getMessageFieldName(size_t fieldId, bool withDataFields = true) {
 }
 
 Message::Message(const string circuit, const string level, const string name,
-    const bool isWrite, const bool isPassive, const string comment,
+    const bool isWrite, const bool isPassive, const map<string, string>& attributes,
     const symbol_t srcAddress, const symbol_t dstAddress,
     const vector<symbol_t> id,
-    DataField* data, const bool deleteData,
+    const DataField* data, const bool deleteData,
     const size_t pollPriority,
     Condition* condition)
-    : m_circuit(circuit), m_level(level), m_name(name), m_isWrite(isWrite),
+    : AttributedItem(name, attributes), m_circuit(circuit), m_level(level), m_isWrite(isWrite),
-      m_isPassive(isPassive), m_comment(comment),
+      m_isPassive(isPassive),
       m_srcAddress(srcAddress), m_dstAddress(dstAddress),
       m_id(id), m_data(data), m_deleteData(deleteData),
       m_pollPriority(pollPriority),
       m_usedByCondition(false), m_isScanMessage(false), m_condition(condition),
-      m_lastUpdateTime(0), m_lastChangeTime(0), m_pollCount(0), m_lastPollTime(0) {
+      m_lastUpdateTime(0), m_lastChangeTime(0), m_pollCount(0), m_lastPollTime(0),
-  m_key = createKey(id, isWrite, isPassive, srcAddress, dstAddress);
+      m_key(createKey(id, isWrite, isPassive, srcAddress, dstAddress)) {
   if (circuit == "scan") {
     setScanMessage();
     m_pollPriority = 0;
@@ -183,22 +183,15 @@ Message::Message(const string circuit, const string level, const string name,
 
 Message::Message(const string circuit, const string level, const string name,
     const symbol_t pb, const symbol_t sb,
-    const bool broadcast, DataField* data, const bool deleteData)
+    const bool broadcast, const DataField* data, const bool deleteData)
-    : m_circuit(circuit), m_level(level), m_name(name), m_isWrite(broadcast),
+    : AttributedItem(name), m_circuit(circuit), m_level(level), m_isWrite(broadcast),
-      m_isPassive(false), m_comment(),
+      m_isPassive(false),
       m_srcAddress(SYN), m_dstAddress(broadcast ? BROADCAST : SYN),
-      m_data(data), m_deleteData(deleteData),
+      m_id({pb, sb}), m_data(data), m_deleteData(deleteData),
       m_pollPriority(0),
       m_usedByCondition(false), m_isScanMessage(true), m_condition(NULL),
-      m_lastUpdateTime(0), m_lastChangeTime(0), m_pollCount(0), m_lastPollTime(0) {
+      m_lastUpdateTime(0), m_lastChangeTime(0), m_pollCount(0), m_lastPollTime(0),
-  m_id.push_back(pb);
+      m_key(createKey(pb, sb, broadcast)) {
-  m_id.push_back(sb);
-  uint64_t key = 0;
-  key |= (broadcast ? 0x1fLL : 0x1eLL) << (8 * 7);  // special values for active
-  key |= (uint64_t)(broadcast ? BROADCAST : SYN) << (8 * 6);
-  key |= (uint64_t)pb << (8 * 5);
-  key |= (uint64_t)sb << (8 * 4);
-  m_key = key;
 }
 
 
@@ -214,7 +207,7 @@ Message::Message(const string circuit, const string level, const string name,
  * empty and @p replaceStar is @p true.
  * @return the default if available and value is empty, or the value.
  */
-string getDefault(const string value, map<string, string>& defaults, const string fieldName,
+string getDefault(const string value, const map<string, string>& defaults, const string fieldName,
     bool replaceStar = false, bool required = false) {
   if (defaults.empty()) {
     return value;
@@ -222,7 +215,8 @@ string getDefault(const string value, map<string, string>& defaults, const strin
   if (value.length() == 0 && replaceStar && required) {
     return value;
   }
-  string defaultStr = defaults[fieldName];
+  auto it = defaults.find(fieldName);
+  const string defaultStr = it == defaults.end() ? "" : it->second;
   if (!replaceStar || defaultStr.empty()) {
     return value.length() > 0 ? value : defaultStr;
   }
@@ -279,6 +273,15 @@ uint64_t Message::createKey(MasterSymbolString& master, size_t maxIdLength, bool
   return key;
 }
 
+uint64_t Message::createKey(const symbol_t pb, const symbol_t sb, const bool broadcast) {
+  uint64_t key = 0;
+  key |= (broadcast ? 0x1fLL : 0x1eLL) << (8 * 7);  // special values for active
+  key |= (uint64_t)(broadcast ? BROADCAST : SYN) << (8 * 6);
+  key |= (uint64_t)pb << (8 * 5);
+  key |= (uint64_t)sb << (8 * 4);
+  return key;
+}
+
 result_t Message::parseId(string input, vector<symbol_t>& id) {
   istringstream in(input);
   while (!in.eof()) {
@@ -314,8 +317,9 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
   bool isWrite = false, isPassive = false;
   string defaultName;
   size_t pollPriority = 0;
-  string typeStr = row["type"];
+  string typeStr = pluck(row, "type");
   if (typeStr.empty()) {
+    errorDescription = "empty type";
     return RESULT_ERR_EOF;
   }
   if (typeStr.empty()) {  // default: active read
@@ -341,36 +345,39 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
   }
 
   map<string, string>& defaults = rowDefaults[defaultName];
-  string circuit = getDefault(row["circuit"], defaults, "circuit", true);  // [circuit[#level]]
+  string circuit = getDefault(pluck(row, "circuit"), defaults, "circuit", true);  // [circuit[#level]]
-  string level = getDefault(row["level"], defaults, "level", true);
+  string level = getDefault(pluck(row, "level"), defaults, "level", true);
   size_t pos = circuit.find('#');  // TODO remove some day
   if (pos != string::npos) {
     level = circuit.substr(pos+1);
     circuit.resize(pos);
   }
-  string name = getDefault(row["name"], defaults, "name", true, true);  // name
+  string name = getDefault(pluck(row, "name"), defaults, "name", true, true);  // name
   if (name.empty()) {
-    errorDescription = "name in "+MappedFileReader::combineRow(row);
+    errorDescription = "name";
     return RESULT_ERR_MISSING_ARG;  // empty name
   }
-  string comment = getDefault(row["comment"], defaults, "comment", true);  // [comment]
+  string comment = getDefault(pluck(row, "comment"), defaults, "comment", true);  // [comment]
-  string str = getDefault(row["qq"], defaults, "qq");  // [QQ[;QQ]*]
+  if (!comment.empty()) {
+    row["comment"] = comment;
+  }
+  string str = getDefault(pluck(row, "qq"), defaults, "qq");  // [QQ[;QQ]*]
   symbol_t srcAddress;
   if (str.empty()) {
     srcAddress = SYN;  // no specific source
   } else {
     srcAddress = (symbol_t)parseInt(str.c_str(), 16, 0, 0xff, result);
     if (result != RESULT_OK) {
-      errorDescription = "qq "+str+" in "+MappedFileReader::combineRow(row);
+      errorDescription = "qq "+str;
       return result;
     }
     if (!isMaster(srcAddress)) {
-      errorDescription = "qq "+str+" in "+MappedFileReader::combineRow(row);
+      errorDescription = "qq "+str;
       return RESULT_ERR_INVALID_ADDR;
     }
   }
 
-  str = getDefault(row["zz"], defaults, "zz");  // [ZZ]
+  str = getDefault(pluck(row, "zz"), defaults, "zz");  // [ZZ]
   vector<symbol_t> dstAddresses;
   bool isBroadcastOrMasterDestination = false;
   if (str.empty()) {
@@ -383,11 +390,11 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
       FileReader::trim(token);
       symbol_t dstAddress = (symbol_t)parseInt(token.c_str(), 16, 0, 0xff, result);
       if (result != RESULT_OK) {
-        errorDescription = "zz "+token+" in "+MappedFileReader::combineRow(row);
+        errorDescription = "zz "+token;
         return result;
       }
       if (!isValidAddress(dstAddress)) {
-        errorDescription = "zz "+token+" in "+MappedFileReader::combineRow(row);
+        errorDescription = "zz "+token;
         return RESULT_ERR_INVALID_ADDR;
       }
       bool broadcastOrMaster = (dstAddress == BROADCAST) || isMaster(dstAddress);
@@ -395,7 +402,7 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
         isBroadcastOrMasterDestination = broadcastOrMaster;
         first = false;
       } else if (isBroadcastOrMasterDestination != broadcastOrMaster) {
-        errorDescription = "zz "+token+" in "+MappedFileReader::combineRow(row);
+        errorDescription = "zz "+token;
         return RESULT_ERR_INVALID_ADDR;
       }
       dstAddresses.push_back(dstAddress);
@@ -403,21 +410,21 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
   }
 
   vector<symbol_t> id;
-  str = row["pbsb"];  // [PBSB]
+  str = pluck(row, "pbsb");  // [PBSB]
   bool useDefaults = str.empty();
   if (useDefaults) {
     str = getDefault(str, defaults, "pbsb");
   }
   result = parseId(str, id);
   if (result != RESULT_OK) {
-    errorDescription = "pbsb "+str+" in "+MappedFileReader::combineRow(row);
+    errorDescription = "pbsb "+str;
     return result;
   }
   if (id.size() != 2) {
-    errorDescription = "pbsb "+str+" in "+MappedFileReader::combineRow(row);
+    errorDescription = "pbsb "+str;
     return RESULT_ERR_INVALID_ARG;  // missing/to short/to long PBSB
   }
-  str = row["id"];  // [ID] (optional master data)
+  str = pluck(row, "id");  // [ID] (optional master data)
   string defaultIdPrefix;
   if (useDefaults) {
     defaultIdPrefix = getDefault("", defaults, "id");
@@ -437,7 +444,7 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
     if (lastChainLengthSpecified) {
       chainLength = parseInt(str.substr(lengthPos+1).c_str(), 10, 0, MAX_POS, result);
       if (result != RESULT_OK) {
-        errorDescription = "id "+str+" in "+MappedFileReader::combineRow(row);
+        errorDescription = "id "+str;
         return result;
       }
       str.resize(lengthPos);
@@ -445,11 +452,11 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
     vector<symbol_t> chainId = id;
     result = parseId(str, chainId);
     if (result != RESULT_OK) {
-      errorDescription = "id "+str+" in "+MappedFileReader::combineRow(row);
+      errorDescription = "id "+str;
       return result;
     }
     if (!chainIds.empty() && chainId.size() != chainIds.front().size()) {
-      errorDescription = "id length "+str+" in "+MappedFileReader::combineRow(row);
+      errorDescription = "id length "+str;
       return RESULT_ERR_INVALID_LIST;
     }
     chainIds.push_back(chainId);
@@ -467,7 +474,7 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
       }
     }
     if (maxLength+chainLength > 255) {
-      errorDescription = "id length "+str+" in "+MappedFileReader::combineRow(row);
+      errorDescription = "id length "+str;
       return RESULT_ERR_INVALID_POS;
     }
     maxLength += chainLength;
@@ -476,7 +483,7 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
   id = chainIds.front();
   if (chainIds.size() > 1) {
     if (isPassive) {
-      errorDescription = "id (passive) in "+MappedFileReader::combineRow(row);
+      errorDescription = "id (passive)";
       return RESULT_ERR_INVALID_LIST;
     }
     if (id.size() > chainPrefixLength) {
@@ -493,10 +500,10 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
   if (!subDefaults.empty()) {
     subRows.insert(subRows.begin(), subDefaults.begin(), subDefaults.end());
   }
-  DataField* data = NULL;
+  const DataField* data = NULL;
   if (subRows.empty()) {
-    vector<SingleDataField*> fields;
+    vector<const SingleDataField*> fields;
-    data = new DataFieldSet("", "", fields);
+    data = new DataFieldSet("", fields);
   } else {
     result = DataField::create(subRows, errorDescription, templates, data, isWrite, false,
         isBroadcastOrMasterDestination, maxLength);
@@ -508,7 +515,7 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
       || data->getLength(pt_slaveData, maxLength) > maxLength) {
     // max NN exceeded
     delete data;
-    errorDescription = "data length in "+MappedFileReader::combineRow(row);
+    errorDescription = "data length";
     return RESULT_ERR_INVALID_POS;
   }
   unsigned int index = 0;
@@ -523,10 +530,10 @@ result_t Message::create(map<string, string> row, vector< map<string, string> >
     }
     Message* message;
     if (chainIds.size() > 1) {
-      message = new ChainedMessage(useCircuit, level, name, isWrite, comment, srcAddress, dstAddress, id, chainIds,
+      message = new ChainedMessage(useCircuit, level, name, isWrite, row, srcAddress, dstAddress, id, chainIds,
           chainLengths, data, index == 0, pollPriority, condition);
     } else {
-      message = new Message(useCircuit, level, name, isWrite, isPassive, comment, srcAddress, dstAddress, id, data,
+      message = new Message(useCircuit, level, name, isWrite, isPassive, row, srcAddress, dstAddress, id, data,
           index == 0, pollPriority, condition);
     }
     messages.push_back(message);
@@ -561,9 +568,9 @@ bool Message::extractFieldIds(string str, vector<size_t>& fields, bool checkAbbr
   return !fields.empty();
 }
 
-Message* Message::derive(const symbol_t dstAddress, const symbol_t srcAddress, const string circuit) {
+Message* Message::derive(const symbol_t dstAddress, const symbol_t srcAddress, const string circuit) const {
   Message* result = new Message(circuit.length() == 0 ? m_circuit : circuit, m_level, m_name,
-    m_isWrite, m_isPassive, m_comment,
+    m_isWrite, m_isPassive, m_attributes,
     srcAddress == SYN ? m_srcAddress : srcAddress, dstAddress,
     m_id, m_data, false,
     m_pollPriority, m_condition);
@@ -573,7 +580,7 @@ Message* Message::derive(const symbol_t dstAddress, const symbol_t srcAddress, c
   return result;
 }
 
-Message* Message::derive(const symbol_t dstAddress, const bool extendCircuit) {
+Message* Message::derive(const symbol_t dstAddress, const bool extendCircuit) const {
   if (extendCircuit) {
     ostringstream out;
     out << m_circuit << '.' << hex << setw(2) << setfill('0') << static_cast<unsigned>(dstAddress);
@@ -604,7 +611,8 @@ bool Message::checkLevel(const string level, const string checkLevels) {
   }
   return false;
 }
-bool Message::checkIdPrefix(vector<symbol_t>& id) {
+
+bool Message::checkIdPrefix(const vector<symbol_t>& id) const {
   if (id.size() > m_id.size()) {
     return false;
   }
@@ -616,7 +624,7 @@ bool Message::checkIdPrefix(vector<symbol_t>& id) {
   return true;
 }
 
-bool Message::checkId(MasterSymbolString& master, size_t* index) {
+bool Message::checkId(const MasterSymbolString& master, size_t* index) const {
   size_t idLen = getIdLength();
   if (master.getDataSize() < idLen) {
     return false;
@@ -632,7 +640,7 @@ bool Message::checkId(MasterSymbolString& master, size_t* index) {
   return true;
 }
 
-bool Message::checkId(Message& other) {
+bool Message::checkId(Message& other) const {
   size_t idLen = getIdLength();
   if (idLen != other.getIdLength() || getCount() > 1) {  // only equal for non-chained messages
     return false;
@@ -640,7 +648,7 @@ bool Message::checkId(Message& other) {
   return other.checkIdPrefix(m_id);
 }
 
-uint64_t Message::getDerivedKey(const symbol_t dstAddress) {
+uint64_t Message::getDerivedKey(const symbol_t dstAddress) const {
   return (m_key & ~(0xffLL << (8*6))) | (uint64_t)dstAddress << (8*6);
 }
 
@@ -670,7 +678,7 @@ bool Message::isAvailable() {
   return (m_condition == NULL) || m_condition->isTrue();
 }
 
-bool Message::hasField(const char* fieldName, bool numeric) {
+bool Message::hasField(const char* fieldName, bool numeric) const {
   return m_data->hasField(fieldName, numeric);
 }
 
@@ -749,8 +757,8 @@ result_t Message::storeLastData(MasterSymbolString& master, SlaveSymbolString& s
 }
 
 result_t Message::storeLastData(MasterSymbolString& data, size_t index) {
-  if (data.size() > 0
+  if (data.size() > 0 && (m_isWrite || this->m_dstAddress == BROADCAST || isMaster(this->m_dstAddress)
-      && (m_isWrite || this->m_dstAddress == BROADCAST || isMaster(this->m_dstAddress))) {
+      || data.getDataSize() + 2 > m_id.size())) {
     time(&m_lastUpdateTime);
   }
   switch (data.compareTo(m_lastMasterData)) {
@@ -761,6 +769,7 @@ result_t Message::storeLastData(MasterSymbolString& data, size_t index) {
   case 2:  // only master address is different
     m_lastMasterData = data;
     break;
+  // else: identical
   }
   return RESULT_OK;
 }
@@ -772,12 +781,13 @@ result_t Message::storeLastData(SlaveSymbolString& data, size_t index) {
   if (data != m_lastSlaveData) {
     m_lastChangeTime = m_lastUpdateTime;
     m_lastSlaveData = data;
+    const SlaveSymbolString& chk = getLastSlaveData();
   }
   return RESULT_OK;
 }
 
 result_t Message::decodeLastMasterData(ostringstream& output, OutputFormat outputFormat,
-    bool leadingSeparator, const char* fieldName, ssize_t fieldIndex) {
+    bool leadingSeparator, const char* fieldName, ssize_t fieldIndex) const {
   size_t offset = m_id.size() - 2;
   result_t result = m_data->read(m_lastMasterData, offset,
       output, outputFormat, -1, leadingSeparator, fieldName, fieldIndex);
@@ -791,7 +801,7 @@ result_t Message::decodeLastMasterData(ostringstream& output, OutputFormat outpu
 }
 
 result_t Message::decodeLastSlaveData(ostringstream& output, OutputFormat outputFormat,
-    bool leadingSeparator, const char* fieldName, ssize_t fieldIndex) {
+    bool leadingSeparator, const char* fieldName, ssize_t fieldIndex) const {
   result_t result = m_data->read(m_lastSlaveData, 0,
       output, outputFormat, -1, leadingSeparator, fieldName, fieldIndex);
   if (result < RESULT_OK) {
@@ -804,7 +814,7 @@ result_t Message::decodeLastSlaveData(ostringstream& output, OutputFormat output
 }
 
 result_t Message::decodeLastData(ostringstream& output, OutputFormat outputFormat,
-    bool leadingSeparator, const char* fieldName, ssize_t fieldIndex) {
+    bool leadingSeparator, const char* fieldName, ssize_t fieldIndex) const {
   size_t startPos = output.str().length();
   result_t result = m_data->read(m_lastMasterData, getIdLength(), output, outputFormat, -1,
       leadingSeparator, fieldName, fieldIndex);
@@ -825,7 +835,7 @@ result_t Message::decodeLastData(ostringstream& output, OutputFormat outputForma
   return result;
 }
 
-result_t Message::decodeLastDataNumField(unsigned int& output, const char* fieldName, ssize_t fieldIndex) {
+result_t Message::decodeLastDataNumField(unsigned int& output, const char* fieldName, ssize_t fieldIndex) const {
   result_t result = m_data->read(m_lastMasterData, getIdLength(), output, fieldName, fieldIndex);
   if (result < RESULT_OK) {
     return result;
@@ -842,7 +852,7 @@ result_t Message::decodeLastDataNumField(unsigned int& output, const char* field
   return result;
 }
 
-bool Message::isLessPollWeight(const Message* other) {
+bool Message::isLessPollWeight(const Message* other) const {
   size_t tprio = m_pollPriority;
   size_t oprio = other->m_pollPriority;
   size_t tw = tprio * m_pollCount;
@@ -909,7 +919,7 @@ void Message::dumpHeader(ostream& output, vector<size_t>* fieldIds) {
   }
 }
 
-void Message::dump(ostream& output, vector<size_t>* fieldIds, bool withConditions) {
+void Message::dump(ostream& output, vector<size_t>* fieldIds, bool withConditions) const {
   bool first = true;
   if (fieldIds == NULL) {
     for (size_t fieldId = MESSAGEFIELD_RANGE_MIN; fieldId <= MESSAGEFIELD_RANGE_MAX; fieldId++) {
@@ -935,7 +945,7 @@ void Message::dump(ostream& output, vector<size_t>* fieldIds, bool withCondition
   }
 }
 
-void Message::dumpField(ostream& output, size_t fieldId, bool withConditions) {
+void Message::dumpField(ostream& output, size_t fieldId, bool withConditions) const {
   switch (fieldId) {
   case MESSAGEFIELD_TYPE:
     if (withConditions && m_condition != NULL) {
@@ -956,16 +966,16 @@ void Message::dumpField(ostream& output, size_t fieldId, bool withConditions) {
     }
     break;
   case MESSAGEFIELD_CIRCUIT:
-    DataField::dumpString(output, m_circuit, false);
+    dumpString(output, m_circuit, false);
     break;
   case MESSAGEFIELD_LEVEL:
-    DataField::dumpString(output, m_level, false);
+    dumpString(output, m_level, false);
     break;
   case MESSAGEFIELD_NAME:
-    DataField::dumpString(output, m_name, false);
+    dumpString(output, m_name, false);
     break;
   case MESSAGEFIELD_COMMENT:
-    DataField::dumpString(output, m_comment, false);
+    dumpAttribute(output, "comment", false);
     break;
   case MESSAGEFIELD_QQ:
     if (m_srcAddress != SYN) {
@@ -997,14 +1007,14 @@ void Message::dumpField(ostream& output, size_t fieldId, bool withConditions) {
 
 
 ChainedMessage::ChainedMessage(const string circuit, const string level, const string name,
-    const bool isWrite, const string comment,
+    const bool isWrite, const map<string, string>& attributes,
     const symbol_t srcAddress, const symbol_t dstAddress,
     const vector<symbol_t> id,
     vector< vector<symbol_t> > ids, vector<size_t> lengths,
-    DataField* data, const bool deleteData,
+    const DataField* data, const bool deleteData,
     const size_t pollPriority,
     Condition* condition)
-    : Message(circuit, level, name, isWrite, false, comment,
+    : Message(circuit, level, name, isWrite, false, attributes,
       srcAddress, dstAddress, id,
       data, deleteData, pollPriority, condition),
       m_ids(ids), m_lengths(lengths),
@@ -1033,9 +1043,9 @@ ChainedMessage::~ChainedMessage() {
   free(m_lastSlaveUpdateTimes);
 }
 
-Message* ChainedMessage::derive(const symbol_t dstAddress, const symbol_t srcAddress, const string circuit) {
+Message* ChainedMessage::derive(const symbol_t dstAddress, const symbol_t srcAddress, const string circuit) const {
   ChainedMessage* result = new ChainedMessage(circuit.length() == 0 ? m_circuit : circuit, m_level, m_name,
-    m_isWrite, m_comment,
+    m_isWrite, m_attributes,
     srcAddress == SYN ? m_srcAddress : srcAddress, dstAddress,
     m_id, m_ids, m_lengths, m_data, false,
     m_pollPriority, m_condition);
@@ -1045,7 +1055,7 @@ Message* ChainedMessage::derive(const symbol_t dstAddress, const symbol_t srcAdd
   return result;
 }
 
-bool ChainedMessage::checkId(MasterSymbolString& master, size_t* index) {
+bool ChainedMessage::checkId(const MasterSymbolString& master, size_t* index) const {
   size_t idLen = getIdLength();
   if (master.getDataSize() < idLen) {
     return false;
@@ -1076,7 +1086,7 @@ bool ChainedMessage::checkId(MasterSymbolString& master, size_t* index) {
   return false;
 }
 
-bool ChainedMessage::checkId(Message& other) {
+bool ChainedMessage::checkId(Message& other) const {
   size_t idLen = getIdLength();
   if (idLen != other.getIdLength() || other.getCount() == 1) {  // only equal for chained messages
     return false;
@@ -1242,7 +1252,7 @@ result_t ChainedMessage::combineLastParts() {
   return result;
 }
 
-void ChainedMessage::dumpField(ostream& output, size_t fieldId, bool withConditions) {
+void ChainedMessage::dumpField(ostream& output, size_t fieldId, bool withConditions) const {
   if (fieldId != MESSAGEFIELD_ID) {
     Message::dumpField(output, fieldId, withConditions);
     return;
@@ -1270,10 +1280,9 @@ void ChainedMessage::dumpField(ostream& output, size_t fieldId, bool withConditi
  * @param onlyAvailable true to include only available messages (default true), false to also include messages that
  * are currently not available (e.g. due to unresolved or false conditions).
  */
-Message* getFirstAvailable(vector<Message*> &messages, MasterSymbolString* sameIdExtAs,
+Message* getFirstAvailable(const vector<Message*> &messages, const MasterSymbolString* sameIdExtAs,
     const bool onlyAvailable = true) {
-  for (vector<Message*>::iterator msgIt = messages.begin(); msgIt != messages.end(); msgIt++) {
+  for (auto message : messages) {
-    Message* message = *msgIt;
     if (sameIdExtAs && !message->checkId(*sameIdExtAs)) {
       continue;
     }
@@ -1291,10 +1300,9 @@ Message* getFirstAvailable(vector<Message*> &messages, MasterSymbolString* sameI
  * @param onlyAvailable true to include only available messages (default true), false to also include messages that
  * are currently not available (e.g. due to unresolved or false conditions).
  */
-Message* getFirstAvailable(vector<Message*> &messages, Message* sameIdExtAs = NULL,
+Message* getFirstAvailable(const vector<Message*> &messages, Message* sameIdExtAs = NULL,
     const bool onlyAvailable = true) {
-  for (vector<Message*>::iterator msgIt = messages.begin(); msgIt != messages.end(); msgIt++) {
+  for (auto message : messages) {
-    Message* message = *msgIt;
     if (sameIdExtAs && !message->checkId(*sameIdExtAs)) {
       continue;
     }
@@ -1381,7 +1389,7 @@ result_t splitValues(string valueList, vector<unsigned int>& valueRanges) {
 
 result_t Condition::create(const string condName, map<string, string> row, map<string, string> rowDefaults,
     SimpleCondition*& returnValue) {
-  // name,circuit,messagename,[comment],[fieldname],[ZZ],values
+  // type=name,circuit,name=messagename,[comment],qq=[fieldname],[ZZ],pbsb=values
   string circuit = row["circuit"];  // circuit[#level]
   string level;
   size_t pos = circuit.find('#');
@@ -1414,7 +1422,10 @@ result_t Condition::create(const string condName, map<string, string> row, map<s
     circuit = rowDefaults["circuit"];
   }
   string valueList = row["pbsb"];
-  if (valueList.length() == 0) {
+  if (valueList.empty()) {
+    valueList = row["id"];
+  }
+  if (valueList.empty()) {
     returnValue = new SimpleCondition(condName, condName, circuit, level, name, dstAddress, field);
     return RESULT_OK;
   }
@@ -1438,7 +1449,7 @@ result_t Condition::create(const string condName, map<string, string> row, map<s
   return RESULT_OK;
 }
 
-SimpleCondition* SimpleCondition::derive(string valueList) {
+SimpleCondition* SimpleCondition::derive(string valueList) const {
   if (valueList.empty()) {
     return NULL;
   }
@@ -1468,7 +1479,7 @@ SimpleCondition* SimpleCondition::derive(string valueList) {
   return new SimpleNumericCondition(name, m_refName, m_circuit, m_level, m_name, m_dstAddress, m_field, valueRanges);
 }
 
-void SimpleCondition::dump(ostream& output, bool matched) {
+void SimpleCondition::dump(ostream& output, bool matched) const {
   if (matched) {
     if (!m_isTrue) {
       return;
@@ -1518,7 +1529,7 @@ result_t SimpleCondition::resolve(MessageMap* messages, ostringstream& errorMess
       }
       // clone the message with dedicated dstAddress if necessary
       uint64_t key = message->getDerivedKey(m_dstAddress);
-      vector<Message*>* derived = messages->getByKey(key);
+      const vector<Message*>* derived = messages->getByKey(key);
       if (derived == NULL) {
         message = message->derive(m_dstAddress, true);
         messages->add(message);
@@ -1600,17 +1611,15 @@ bool SimpleStringCondition::checkValue(Message* message, string field) {
 }
 
 
-void CombinedCondition::dump(ostream& output, bool matched) {
+void CombinedCondition::dump(ostream& output, bool matched) const {
-  for (vector<Condition*>::iterator it = m_conditions.begin(); it != m_conditions.end(); it++) {
+  for (auto condition : m_conditions) {
-    Condition* condition = *it;
     condition->dump(output, matched);
   }
 }
 
 result_t CombinedCondition::resolve(MessageMap* messages, ostringstream& errorMessage,
     void (*readMessageFunc)(Message* message)) {
-  for (vector<Condition*>::iterator it = m_conditions.begin(); it != m_conditions.end(); it++) {
+  for (auto condition : m_conditions) {
-    Condition* condition = *it;
     ostringstream dummy;
     result_t ret = condition->resolve(messages, dummy, readMessageFunc);
     if (ret != RESULT_OK) {
@@ -1662,23 +1671,28 @@ result_t Instruction::create(const string& contextPath, const string type,
   return RESULT_ERR_INVALID_ARG;
 }
 
-string Instruction::getDestination() {
+string Instruction::getDestination() const {
   // ZZ.circuit[.suffix]
   string ret;
-  if (!m_defaults["zz"].empty()) {
+  auto it = m_defaults.find("zz");
-    ret = m_defaults["zz"];
+  if (it != m_defaults.end() && !it->second.empty()) {
+    ret = it->second;
   }
-  if (!m_defaults["circuit"].empty() || !m_defaults["suffix"].empty()) {
+  it = m_defaults.find("circuit");
+  string circuit = it == m_defaults.end() ? "" : it->second;
+  it = m_defaults.find("suffix");
+  string suffix = it == m_defaults.end() ? "" : it->second;
+  if (!circuit.empty() || !suffix.empty()) {
     if (!ret.empty()) {
       ret += ".";
     }
-    if (m_defaults["circuit"].empty()) {
+    if (circuit.empty()) {
       ret += "*";
     } else {
-      ret += m_defaults["circuit"];
+      ret += circuit;
     }
-    if (!m_defaults["suffix"].empty()) {
+    if (!suffix.empty()) {
-      ret += m_defaults["suffix"];
+      ret += suffix;
     }
   }
   return ret;
@@ -1725,6 +1739,8 @@ result_t LoadInstruction::execute(MessageMap* messages, ostringstream& log, Cond
 }
 
 
+vector<string> MessageMap::s_noFiles;
+
 result_t MessageMap::add(Message* message, bool storeByName) {
   uint64_t key = message->getKey();
   bool conditional = message->isConditional();
@@ -1763,7 +1779,6 @@ result_t MessageMap::add(Message* message, bool storeByName) {
       }
     }
     m_messagesByName[nameKey].push_back(message);
-
     nameKey = string(isPassive ? "-P" : (isWrite ? "-W" : "-R")) + name;  // also store without circuit
     map<string, vector<Message*> >::iterator nameIt = m_messagesByName.find(nameKey);
     if (nameIt == m_messagesByName.end()) {
@@ -1800,7 +1815,7 @@ result_t MessageMap::add(Message* message, bool storeByName) {
   return RESULT_OK;
 }
 
-result_t MessageMap::getFieldMap(vector<string>& row, string& errorDescription) {
+result_t MessageMap::getFieldMap(vector<string>& row, string& errorDescription) const {
   // type (r[1-9];w;u),circuit,name,[comment],[QQ],ZZ,PBSB,[ID],field1,part (m/s),datatypes/templates,divider/values,
   //  unit,comment
   // minimum: type,name,PBSB,field,datatype
@@ -1826,55 +1841,56 @@ result_t MessageMap::getFieldMap(vector<string>& row, string& errorDescription)
   bool inDataFields = false;
   map<string, string> seen;
   for (auto &name : row) {
-    tolower(name);
+    string useName = name;
-    size_t fieldId;
+    tolower(useName);
     if (inDataFields) {
-      fieldId = getDataFieldId(name);
+      size_t fieldId = getDataFieldId(useName);
-      if (fieldId == UINT_MAX) {
+      if (fieldId != UINT_MAX) {
-        errorDescription = "unknown field " + name;
+        useName = getDataFieldName(fieldId);
-        return RESULT_ERR_INVALID_ARG;
+        if (seen.find(useName) != seen.end()) {
-      }
+          if (seen.find("name") == seen.end() || seen.find("type") == seen.end()) {
-      if (seen.find(name) != seen.end()) {
+            errorDescription = "missing field name/type as of already seen "+useName;
-        if (seen.find("name") == seen.end() || seen.find("type") == seen.end()) {
+            return RESULT_ERR_EOF;  // require at least name and type
-          return RESULT_ERR_EOF;  // require at least name and type
+          }
+          seen.clear();
         }
-        seen.clear();
-        name = "*" + getDataFieldName(fieldId);  // data field repetition
-      } else {
-        name = getDataFieldName(fieldId);
       }
     } else {
-      fieldId = getMessageFieldId(name);
+      size_t fieldId = getMessageFieldId(useName);
-      if (fieldId == UINT_MAX) {
+      if (fieldId != UINT_MAX && (fieldId != MESSAGEFIELD_NAME || seen.find("name") == seen.end())) {
-        fieldId = getDataFieldId(name);
+        useName = getMessageFieldName(fieldId);
-        if (fieldId == UINT_MAX) {
-          errorDescription = "unknown field " + name;
-          return RESULT_ERR_INVALID_ARG;
-        }
-        if (seen.find("type") == seen.end() || seen.find("name") == seen.end() || seen.find("pbsb") == seen.end()) {
-          return RESULT_ERR_EOF;  // require at least type, name, and pbsb
-        }
-        inDataFields = true;
-        seen.clear();
-        name = "*" + getDataFieldName(fieldId);
       } else {
-        if (seen.find(name) != seen.end()) {
+        fieldId = getDataFieldId(useName);
-          errorDescription = "duplicate field " + name;
+        if (fieldId != UINT_MAX) {
-          return RESULT_ERR_INVALID_ARG;
+          useName = getDataFieldName(fieldId);
+          if (seen.find("type") == seen.end() || seen.find("name") == seen.end() || seen.find("pbsb") == seen.end()) {
+            errorDescription = "missing message name/type/pbsb";
+            return RESULT_ERR_EOF;  // require at least type, name, and pbsb
+          }
+          inDataFields = true;
+          seen.clear();
         }
-        name = getMessageFieldName(fieldId);
+      }
+      if (!inDataFields && seen.find(useName) != seen.end()) {
+        errorDescription = "duplicate message " + useName;
+        return RESULT_ERR_INVALID_ARG;
       }
     }
-    seen[name] = name;
+    if (seen.empty() && inDataFields) {
+      name = "*" + useName;  // data field repetition
+    } else {
+      name = useName;
+    }
+    seen[useName] = useName;
   }
   if (inDataFields) {
     if (seen.find("name") == seen.end() || seen.find("type") == seen.end()) {
+      errorDescription = "missing field name/type";
       return RESULT_ERR_EOF;  // require at least name and type
     }
-  } else {
+  } else if (seen.find("type") == seen.end() || seen.find("name") == seen.end() || seen.find("pbsb") == seen.end()) {
-    if (seen.find("type") == seen.end() || seen.find("name") == seen.end() || seen.find("pbsb") == seen.end()) {
+    errorDescription = "missing message name/type/pbsb";
-      return RESULT_ERR_EOF;  // require at least type, name, and pbsb
+    return RESULT_ERR_EOF;  // require at least type, name, and pbsb
-    }
   }
   return RESULT_OK;
 }
@@ -1884,9 +1900,13 @@ result_t MessageMap::addDefaultFromFile(map<string, string>& row, vector< map<st
   // check for condition in defaults
   string type = row["type"];
   row.erase("type");
+  auto mainDefaults = getDefaults().find("");
+  map<string, string> defaults;
+  if (mainDefaults != getDefaults().end()) {
+    defaults = mainDefaults->second;
+  }
   if (!type.empty() && type[0] == '[' && type[type.length()-1] == ']') {
     // condition
-    map<string, string> defaults = getDefaults()[""];
     type = type.substr(1, type.length()-2);
     if (type.find('[') != string::npos || type.find(']') != string::npos) {
       errorDescription = "invalid condition name "+type;
@@ -1907,41 +1927,40 @@ result_t MessageMap::addDefaultFromFile(map<string, string>& row, vector< map<st
     m_conditions[key] = condition;
     return RESULT_OK;
   }
-  if (!type.empty()) {
+  if (type.empty()) {
-    map<string, string> defaults = getDefaults()[""];
+    errorDescription = "invalid default definition";
-    string defaultCircuit = defaults["circuit"];
+    return RESULT_ERR_INVALID_ARG;
-    string defaultSuffix = defaults["suffix"];
+  }
-    defaults.erase("suffix");
+  string defaultCircuit = defaults["circuit"];
-    for (auto entry : row) {
+  string defaultSuffix = defaults["suffix"];
-      string value = entry.second;
+  defaults.erase("suffix");
-      if (entry.first == "circuit" && !defaultCircuit.empty()) {  // TODO remove some day
+  for (auto entry : row) {
-        if (value.empty()) {
+    string value = entry.second;
-          value = defaultCircuit+defaultSuffix;  // set default circuit and suffix: "circuit[.suffix]"
+    if (entry.first == "circuit" && !defaultCircuit.empty()) {  // TODO remove some day
-        } else if (value[0] == '#') {
+      if (value.empty()) {
-          // move access level behind default circuit and suffix: "circuit[.suffix]#level"
+        value = defaultCircuit+defaultSuffix;  // set default circuit and suffix: "circuit[.suffix]"
-          value = defaultCircuit+defaultSuffix+value;
+      } else if (value[0] == '#') {
-        } else if (!defaultSuffix.empty() && value.find_last_of('.') == string::npos) {
+        // move access level behind default circuit and suffix: "circuit[.suffix]#level"
-          // circuit suffix not yet present
+        value = defaultCircuit+defaultSuffix+value;
-          size_t pos = value.find_first_of('#');
+      } else if (!defaultSuffix.empty() && value.find_last_of('.') == string::npos) {
-          if (pos == string::npos) {
+        // circuit suffix not yet present
-            value += defaultSuffix;  // append default suffix: "circuit.suffix"
+        size_t pos = value.find_first_of('#');
-          } else {
+        if (pos == string::npos) {
-            // insert default suffix: "circuit.suffix#level"
+          value += defaultSuffix;  // append default suffix: "circuit.suffix"
-            value = value.substr(0, pos)+defaultSuffix+value.substr(pos);
+        } else {
-          }
+          // insert default suffix: "circuit.suffix#level"
+          value = value.substr(0, pos)+defaultSuffix+value.substr(pos);
         }
       }
-      if (!value.empty() || defaults[entry.first].empty()) {
-        defaults[entry.first] = value;
-      }
     }
-    getDefaults()[type] = defaults;
+    if (!value.empty() || defaults[entry.first].empty()) {
-    vector< map<string, string> > subDefaults = subRows;  // ensure to have a copy
+      defaults[entry.first] = value;
-    getSubDefaults()[type] = subDefaults;
+    }
-    return RESULT_OK;
   }
-  errorDescription = "invalid default definition";
+  getDefaults()[type] = defaults;
-  return RESULT_ERR_INVALID_ARG;
+  vector< map<string, string> > subDefaults = subRows;  // ensure to have a copy
+  getSubDefaults()[type] = subDefaults;
+  return RESULT_OK;
 }
 
 result_t MessageMap::readConditions(string& types, const string filename, string& errorDescription,
@@ -1950,7 +1969,7 @@ result_t MessageMap::readConditions(string& types, const string filename, string
   if (types.length() > 0 && types[0] == '[' && (pos=types.find_last_of(']')) != string::npos) {
     // check if combined or simple condition is already known
     const string combinedkey = filename+":"+types.substr(1, pos-1);
-    map<string, Condition*>::iterator it = m_conditions.find(combinedkey);
+    auto it = m_conditions.find(combinedkey);
     if (it != m_conditions.end()) {
       condition = it->second;
       types = types.substr(pos+1);
@@ -2005,7 +2024,7 @@ result_t MessageMap::readConditions(string& types, const string filename, string
 }
 
 bool MessageMap::extractDefaultsFromFilename(string filename, map<string, string>& defaults,
-    symbol_t* destAddress, unsigned int* software, unsigned int* hardware) {
+    symbol_t* destAddress, unsigned int* software, unsigned int* hardware) const {
   string ident, circuit, suffix;
   unsigned int sw = UINT_MAX, hw = UINT_MAX;
   string remain = filename;
@@ -2180,7 +2199,7 @@ Message* MessageMap::getScanMessage(const symbol_t dstAddress) {
     return NULL;
   }
   uint64_t key = m_scanMessage->getDerivedKey(dstAddress);
-  vector<Message*>* msgs = getByKey(key);
+  const vector<Message*>* msgs = getByKey(key);
   if (msgs != NULL) {
     return msgs->front();
   }
@@ -2220,12 +2239,11 @@ result_t MessageMap::resolveCondition(Condition* condition, string& errorDescrip
 result_t MessageMap::executeInstructions(ostringstream& log, void (*readMessageFunc)(Message* message)) {
   result_t overallResult = RESULT_OK;
   vector<string> remove;
-  for (map<string, vector<Instruction*> >::iterator it = m_instructions.begin(); it != m_instructions.end(); it++) {
+  for (auto& it : m_instructions) {
-    vector<Instruction*> instructions = it->second;
+    auto& instructions = it.second;
     bool removeSingletons = false;
     vector<Instruction*> remain;
-    for (vector<Instruction*>::iterator lit = instructions.begin(); lit != instructions.end(); lit++) {
+    for (auto instruction : instructions) {
-      Instruction* instruction = *lit;
       if (removeSingletons && instruction->isSingleton()) {
         delete instruction;
         continue;
@@ -2238,6 +2256,11 @@ result_t MessageMap::executeInstructions(ostringstream& log, void (*readMessageF
             instruction->isSingleton()?readMessageFunc:NULL);
         if (result != RESULT_OK) {
           overallResult = result;
+          log << "error resolving condition for \"" << instruction->getDestination() << "\": "
+              << getResultCode(result);
+          if (!errorDescription.empty()) {
+            log << " " << errorDescription;
+          }
         } else if (condition->isTrue()) {
           execute = true;
         }
@@ -2268,13 +2291,13 @@ result_t MessageMap::executeInstructions(ostringstream& log, void (*readMessageF
       }
     }
     if (remain.empty()) {
-      remove.push_back(it->first);
+      remove.push_back(it.first);
     } else {
-      it->second = remain;
+      it.second = remain;
     }
   }
-  for (vector<string>::iterator it = remove.begin(); it != remove.end(); it++) {
+  for (auto it : remove) {
-    m_instructions.erase(*it);
+    m_instructions.erase(it);
   }
   return overallResult;
 }
@@ -2289,11 +2312,15 @@ void MessageMap::addLoadedFile(symbol_t address, string file, string comment) {
   }
 }
 
-vector<string>& MessageMap::getLoadedFiles(symbol_t address) {
+const vector<string>& MessageMap::getLoadedFiles(symbol_t address) const {
-  return m_loadedFiles[address];
+  auto files = m_loadedFiles.find(address);
+  if (files != m_loadedFiles.end()) {
+    return files->second;
+  }
+  return s_noFiles;
 }
 
-vector<string> MessageMap::getLoadedFiles() {
+vector<string> MessageMap::getLoadedFiles() const {
   vector<string> ret;
   for (auto& loadedFile : m_loadedFileInfos) {
     ret.push_back(loadedFile.first);
@@ -2301,8 +2328,8 @@ vector<string> MessageMap::getLoadedFiles() {
   return ret;
 }
 
-bool MessageMap::getLoadedFileInfo(string filename, string& comment, size_t* hash, size_t* size, time_t* time) {
+bool MessageMap::getLoadedFileInfo(string filename, string& comment, size_t* hash, size_t* size, time_t* time) const {
-  map<string, LoadedFileInfo>::iterator it = m_loadedFileInfos.find(filename);
+  auto it = m_loadedFileInfos.find(filename);
   if (it == m_loadedFileInfos.end()) {
     comment = "";
     hash = size = 0;
@@ -2322,8 +2349,8 @@ bool MessageMap::getLoadedFileInfo(string filename, string& comment, size_t* has
   return true;
 }
 
-vector<Message*>* MessageMap::getByKey(const uint64_t key) {
+const vector<Message*>* MessageMap::getByKey(const uint64_t key) const {
-  map<uint64_t, vector<Message*> >::iterator it = m_messagesByKey.find(key);
+  auto it = m_messagesByKey.find(key);
   if (it != m_messagesByKey.end()) {
     return &it->second;
   }
@@ -2331,7 +2358,7 @@ vector<Message*>* MessageMap::getByKey(const uint64_t key) {
 }
 
 Message* MessageMap::find(const string& circuit, const string& name, const string& levels, const bool isWrite,
-    const bool isPassive) {
+    const bool isPassive) const {
   string lcircuit = circuit;
   FileReader::tolower(lcircuit);
   string lname = name;
@@ -2345,7 +2372,7 @@ Message* MessageMap::find(const string& circuit, const string& name, const strin
     } else {
       continue;  // not allowed without circuit
     }
-    map<string, vector<Message*> >::iterator it = m_messagesByName.find(key);
+    auto it = m_messagesByName.find(key);
     if (it != m_messagesByName.end()) {
       Message* message = getFirstAvailable(it->second);
       if (message && message->hasLevel(levels)) {
@@ -2359,7 +2386,7 @@ Message* MessageMap::find(const string& circuit, const string& name, const strin
 deque<Message*> MessageMap::findAll(const string& circuit, const string& name, const string& levels,
     const bool completeMatch, const bool withRead, const bool withWrite, const bool withPassive,
     const bool includeEmptyLevel, const bool onlyAvailable,
-    const time_t since, const time_t until) {
+    const time_t since, const time_t until) const {
   deque<Message*> ret;
   string lcircuit = circuit;
   FileReader::tolower(lcircuit);
@@ -2368,12 +2395,11 @@ deque<Message*> MessageMap::findAll(const string& circuit, const string& name, c
   bool checkCircuit = lcircuit.length() > 0;
   bool checkLevel = levels != "*";
   bool checkName = lname.length() > 0;
-  for (map<string, vector<Message*> >::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
+  for (auto it : m_messagesByName) {
-    if (it->first[0] == '-') {  // avoid duplicates: instances stored multiple times have a key starting with "-"
+    if (it.first[0] == '-') {  // avoid duplicates: instances stored multiple times have a key starting with "-"
       continue;
     }
-    for (vector<Message*>::iterator msgIt = it->second.begin(); msgIt != it->second.end(); msgIt++) {
+    for (auto message : it.second) {
-      Message* message = *msgIt;
       if (checkLevel && !message->hasLevel(levels, includeEmptyLevel)) {
         continue;
       }
@@ -2415,7 +2441,7 @@ deque<Message*> MessageMap::findAll(const string& circuit, const string& name, c
         }
       }
       if (!onlyAvailable || message->isAvailable()) {
-        ret.push_back(*msgIt);
+        ret.push_back(message);
       }
     }
   }
@@ -2424,7 +2450,7 @@ deque<Message*> MessageMap::findAll(const string& circuit, const string& name, c
 }
 
 Message* MessageMap::find(MasterSymbolString& master, bool anyDestination,
-  const bool withRead, const bool withWrite, const bool withPassive, const bool onlyAvailable) {
+  const bool withRead, const bool withWrite, const bool withPassive, const bool onlyAvailable) const {
   if (master.size() >= 5 && master[4] == 0 && anyDestination && master[2] == 0x07 && master[3] == 0x04) {
     return m_scanMessage;
   }
@@ -2448,7 +2474,7 @@ Message* MessageMap::find(MasterSymbolString& master, bool anyDestination,
         }
       }
     }
-    map<uint64_t , vector<Message*> >::iterator it;
+    map<uint64_t, vector<Message*> >::const_iterator it;
     if (withPassive) {
       it = m_messagesByKey.find(key);
       if (it != m_messagesByKey.end()) {
@@ -2596,17 +2622,16 @@ Message* MessageMap::getNextPoll() {
   return ret;
 }
 
-void MessageMap::dump(ostream& output, bool withConditions) {
+void MessageMap::dump(ostream& output, bool withConditions) const {
   bool first = true;
   Message::dumpHeader(output, NULL);
   output << endl;
-  for (map<string, vector<Message*> >::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
+  for (auto it : m_messagesByName) {
-    if (it->first[0] == '-') {  // skip instances stored multiple times (key starting with "-")
+    if (it.first[0] == '-') {  // skip instances stored multiple times (key starting with "-")
       continue;
     }
     if (m_addAll) {
-      for (vector<Message*>::iterator mit = it->second.begin(); mit != it->second.end(); mit++) {
+      for (auto message : it.second) {
-        Message* message = *mit;
         if (!message) {
           continue;
         }
@@ -2618,7 +2643,7 @@ void MessageMap::dump(ostream& output, bool withConditions) {
         message->dump(output, NULL, withConditions);
       }
     } else {
-      Message* message = getFirstAvailable(it->second);
+      Message* message = getFirstAvailable(it.second);
       if (!message) {
         continue;
       }

src/lib/ebus/message.h

@@ -108,7 +108,7 @@ class MessageMap;
 /**
  * Defines parameters of a message sent or received on the bus.
  */
-class Message {
+class Message : public AttributedItem {
   friend class MessageMap;
  public:
   /**
@@ -119,7 +119,7 @@ class Message {
    * @param isWrite whether this is a write message.
    * @param isPassive true if message can only be initiated by a participant other than us,
    * false if message can be initiated by any participant.
-   * @param comment the comment.
+   * @param attributes the additional named attributes.
    * @param srcAddress the source address, or @a SYN for any (only relevant if passive).
    * @param dstAddress the destination address, or @a SYN for any (set later).
    * @param id the primary, secondary, and optional further ID bytes.
@@ -129,10 +129,10 @@ class Message {
    * @param condition the @a Condition for this message, or NULL.
    */
   Message(const string circuit, const string level, const string name,
-      const bool isWrite, const bool isPassive, const string comment,
+      const bool isWrite, const bool isPassive, const map<string, string>& attributes,
       const symbol_t srcAddress, const symbol_t dstAddress,
       const vector<symbol_t> id,
-      DataField* data, const bool deleteData,
+      const DataField* data, const bool deleteData,
       const size_t pollPriority = 0,
       Condition* condition = NULL);
 
@@ -151,7 +151,7 @@ class Message {
    */
   Message(const string circuit, const string level, const string name,
       const symbol_t pb, const symbol_t sb,
-      const bool broadcast, DataField* data, const bool deleteData);
+      const bool broadcast, const DataField* data, const bool deleteData);
 
 
  public:
@@ -184,6 +184,15 @@ class Message {
   static uint64_t createKey(MasterSymbolString& master,
     size_t maxIdLength, bool anyDestination = false);
 
+  /**
+   * Calculate the key for a scan message.
+   * @param pb the primary ID byte.
+   * @param sb the secondary ID byte.
+   * @param broadcast true for broadcast scan message, false for scan message to be sent to a slave address.
+   * @return the key for the scan message.
+   */
+  static uint64_t createKey(const symbol_t pb, const symbol_t sb, const bool broadcast);
+
   /**
    * Get the length field from the key.
    * @param key the key.
@@ -243,7 +252,7 @@ class Message {
    * Return whether this is a special scanning @a Message instance.
    * @return whether this is a special scanning @a Message instance.
    */
-  bool isScanMessage() { return m_isScanMessage; }
+  bool isScanMessage() const { return m_isScanMessage; }
 
   /**
    * Derive a new @a Message from this message.
@@ -253,7 +262,7 @@ class Message {
    * @return the derived @a Message instance.
    */
   virtual Message* derive(const symbol_t dstAddress, const symbol_t srcAddress = SYN,
-      const string circuit = "");
+      const string circuit = "") const;
 
   /**
    * Derive a new @a Message from this message.
@@ -261,7 +270,7 @@ class Message {
    * @param extendCircuit whether to extend the current circuit name with a dot and the new destination address in hex.
    * @return the derived @a ScanMessage instance.
    */
-  Message* derive(const symbol_t dstAddress, const bool extendCircuit);
+  Message* derive(const symbol_t dstAddress, const bool extendCircuit) const;
 
   /**
    * Get the optional circuit name.
@@ -282,7 +291,7 @@ class Message {
    * level to check.
    * @return true when access is granted.
    */
-  bool hasLevel(const string levels, bool includeEmpty = true) {
+  bool hasLevel(const string levels, bool includeEmpty = true) const {
     return m_level.empty() ? (includeEmpty || levels.empty()) : checkLevel(m_level, levels);
   }
 
@@ -294,18 +303,12 @@ class Message {
    */
   static bool checkLevel(const string level, const string checkLevels);
 
-  /**
-   * Get the message name (unique within the same circuit and type).
-   * @return the message name (unique within the same circuit and type).
-   */
-  string getName() const { return m_name; }
-
   /**
    * Get the specified field name.
    * @param fieldIndex the index of the field.
    * @return the field name, or the index as string if not unique or not available.
    */
-  virtual string getFieldName(ssize_t fieldIndex) const { return m_data->getName(fieldIndex); }
+  virtual string getFieldName(const ssize_t fieldIndex) const { return m_data->getName(fieldIndex); }
 
   /**
    * Get whether this is a write message.
@@ -320,12 +323,6 @@ class Message {
    */
   bool isPassive() const { return m_isPassive; }
 
-  /**
-   * Get the comment.
-   * @return the comment.
-   */
-  string getComment() const { return m_comment; }
-
   /**
    * Get the source address.
    * @return the source address, or @a SYN for any.
@@ -361,7 +358,7 @@ class Message {
    * @param id the ID bytes to check against.
    * @return true if the full command ID starts with the given value.
    */
-  bool checkIdPrefix(vector<symbol_t>& id);
+  bool checkIdPrefix(const vector<symbol_t>& id) const;
 
   /**
    * Check the ID against the master @a SymbolString data.
@@ -369,27 +366,27 @@ class Message {
    * @param index the variable in which to store the message part index, or NULL to ignore.
    * @return true if the ID matches, false otherwise.
    */
-  virtual bool checkId(MasterSymbolString& master, size_t* index = NULL);
+  virtual bool checkId(const MasterSymbolString& master, size_t* index = NULL) const;
 
   /**
    * Check the ID against the other @a Message.
    * @param other the other @a Message to check against.
    * @return true if the ID matches, false otherwise.
    */
-  virtual bool checkId(Message& other);
+  virtual bool checkId(Message& other) const;
 
   /**
    * Return the key for storing in @a MessageMap.
    * @return the key for storing in @a MessageMap.
    */
-  uint64_t getKey() { return m_key; }
+  uint64_t getKey() const { return m_key; }
 
   /**
    * Return the derived key for storing in @a MessageMap.
    * @param dstAddress the destination address for the derivation.
    * @return the derived key for storing in @a MessageMap.
    */
-  uint64_t getDerivedKey(const symbol_t dstAddress);
+  uint64_t getDerivedKey(const symbol_t dstAddress) const;
 
   /**
    * Get the polling priority, or 0 for no polling at all.
@@ -427,12 +424,12 @@ class Message {
    * @param numeric true for a numeric field, false for a string field.
    * @return true if the field is available.
    */
-  bool hasField(const char* fieldName, bool numeric = true);
+  bool hasField(const char* fieldName, bool numeric = true) const;
 
   /**
    * @return the number of parts this message is composed of.
    */
-  virtual size_t getCount() { return 1; }
+  virtual size_t getCount() const { return 1; }
 
   /**
    * Prepare the master @a SymbolString for sending a query or command to the bus.
@@ -505,7 +502,7 @@ class Message {
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t decodeLastMasterData(ostringstream& output, OutputFormat outputFormat = 0,
-      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1);
+      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) const;
 
   /**
    * Decode the value from the last stored slave data.
@@ -517,7 +514,7 @@ class Message {
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t decodeLastSlaveData(ostringstream& output, OutputFormat outputFormat = 0,
-      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1);
+      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) const;
 
   /**
    * Decode the value from the last stored data.
@@ -529,7 +526,7 @@ class Message {
    * @return @a RESULT_OK on success, or an error code.
    */
   virtual result_t decodeLastData(ostringstream& output, OutputFormat outputFormat = 0,
-      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1);
+      bool leadingSeparator = false, const char* fieldName = NULL, ssize_t fieldIndex = -1) const;
 
   /**
    * Decode a particular numeric field value from the last stored data.
@@ -538,44 +535,44 @@ class Message {
    * @param fieldIndex the optional index of the named field, or -1.
    * @return @a RESULT_OK on success, or an error code.
    */
-  virtual result_t decodeLastDataNumField(unsigned int& output, const char* fieldName, ssize_t fieldIndex = -1);
+  virtual result_t decodeLastDataNumField(unsigned int& output, const char* fieldName, ssize_t fieldIndex = -1) const;
 
   /**
    * Get the last seen master data.
    * @return the last seen @a MasterSymbolString.
    */
-  MasterSymbolString& getLastMasterData() { return m_lastMasterData; }
+  const MasterSymbolString& getLastMasterData() const { return m_lastMasterData; }
 
   /**
    * Get the last seen slave data.
    * @return the last seen @a SlaveSymbolString.
    */
-  SlaveSymbolString& getLastSlaveData() { return m_lastSlaveData; }
+  const SlaveSymbolString& getLastSlaveData() const { return m_lastSlaveData; }
 
   /**
    * Get the time when this message was last seen with reasonable data.
    * @return the time when this message was last seen, or 0.
    */
-  time_t getLastUpdateTime() { return m_lastUpdateTime; }
+  time_t getLastUpdateTime() const { return m_lastUpdateTime; }
 
   /**
    * Get the time when the message data was last changed.
    * @return the time when the message data was last changed, or 0 if this message was not decoded yet.
    */
-  time_t getLastChangeTime() { return m_lastChangeTime; }
+  time_t getLastChangeTime() const { return m_lastChangeTime; }
 
   /**
    * Get the time when this message was last polled for.
    * @return the time when this message was last polled for, or 0 for never.
    */
-  time_t getLastPollTime() { return m_lastPollTime; }
+  time_t getLastPollTime() const { return m_lastPollTime; }
 
   /**
    * Return whether this @a Message needs to be polled after the other one.
    * @param other the other @a Message to compare with.
    * @return true if this @a Message needs to be polled after the other one.
    */
-  bool isLessPollWeight(const Message* other);
+  bool isLessPollWeight(const Message* other) const;
 
   /**
    * Write the message definition header or parts of it to the @a ostream.
@@ -590,7 +587,7 @@ class Message {
    * @param fieldIds the list of field IDs to write, or NULL for all (see @p MESSAGEFIELD_TYPE constants).
    * @param withConditions whether to include the optional conditions prefix.
    */
-  void dump(ostream& output, vector<size_t>* fieldIds = NULL, bool withConditions = false);
+  void dump(ostream& output, vector<size_t>* fieldIds = NULL, bool withConditions = false) const;
 
   /**
    * Write the specified field to the @a ostream.
@@ -598,7 +595,7 @@ class Message {
    * @param fieldId the field ID to write (see @p MESSAGEFIELD_TYPE constants).
    * @param withConditions whether to include the optional conditions prefix.
    */
-  virtual void dumpField(ostream& output, size_t fieldId, bool withConditions = false);
+  virtual void dumpField(ostream& output, size_t fieldId, bool withConditions = false) const;
 
 
  protected:
@@ -608,9 +605,6 @@ class Message {
   /** the optional access level. */
   const string m_level;
 
-  /** the message name (unique within the same circuit and type). */
-  const string m_name;
-
   /** whether this is a write message. */
   const bool m_isWrite;
 
@@ -618,8 +612,8 @@ class Message {
    * false if message can be initiated by any participant. */
   const bool m_isPassive;
 
-  /** the comment. */
+  /** the additional named attributes. */
-  const string m_comment;
+  const map<string, string> m_attributes;
 
   /** the source address, or @a SYN for any (only relevant if passive). */
   const symbol_t m_srcAddress;
@@ -628,7 +622,7 @@ class Message {
   const symbol_t m_dstAddress;
 
   /** the primary, secondary, and optionally further command ID bytes. */
-  vector<symbol_t> m_id;
+  const vector<symbol_t> m_id;
 
   /**
    * the key for storing in @a MessageMap.
@@ -651,10 +645,10 @@ class Message {
    * <li>bytes 3-0: ID bytes (with cyclic xor if more than 4)</li>
    * </ul>
    */
-  uint64_t m_key;
+  const uint64_t m_key;
 
   /** the @a DataField for encoding/decoding the message. */
-  DataField* m_data;
+  const DataField* m_data;
 
   /** whether to delete the @a DataField during destruction. */
   const bool m_deleteData;
@@ -702,7 +696,7 @@ class ChainedMessage : public Message {
    * @param level the optional access level.
    * @param name the message name (unique within the same circuit and type).
    * @param isWrite whether this is a write message.
-   * @param comment the comment.
+   * @param attributes the additional named attributes.
    * @param srcAddress the source address, or @a SYN for any (only relevant if passive).
    * @param dstAddress the destination address, or @a SYN for any (set later).
    * @param id the primary, secondary, and optional further ID bytes common to each part of the chain.
@@ -714,11 +708,11 @@ class ChainedMessage : public Message {
    * @param condition the @a Condition for this message, or NULL.
    */
   ChainedMessage(const string circuit, const string level, const string name,
-      const bool isWrite, const string comment,
+      const bool isWrite, const map<string, string>& attributes,
       const symbol_t srcAddress, const symbol_t dstAddress,
       const vector<symbol_t> id,
       vector< vector<symbol_t> > ids, vector<size_t> lengths,
-      DataField* data, const bool deleteData,
+      const DataField* data, const bool deleteData,
       const size_t pollPriority,
       Condition* condition = NULL);
 
@@ -726,19 +720,19 @@ class ChainedMessage : public Message {
 
   // @copydoc
   Message* derive(const symbol_t dstAddress, const symbol_t srcAddress = SYN,
-      const string circuit = "") override;
+      const string circuit = "") const override;
 
   // @copydoc
   size_t getIdLength() const override { return m_ids[0].size() - 2; }
 
   // @copydoc
-  bool checkId(MasterSymbolString& master, size_t* index = NULL) override;
+  bool checkId(const MasterSymbolString& master, size_t* index = NULL) const override;
 
   // @copydoc
-  bool checkId(Message& other) override;
+  bool checkId(Message& other) const override;
 
   // @copydoc
-  size_t getCount() override { return m_ids.size(); }
+  size_t getCount() const override { return m_ids.size(); }
 
 
  protected:
@@ -765,7 +759,7 @@ class ChainedMessage : public Message {
 
  protected:
   // @copydoc
-  void dumpField(ostream& output, size_t fieldId, bool withConditions = false) override;
+  void dumpField(ostream& output, size_t fieldId, bool withConditions = false) const override;
 
 
  private:
@@ -860,14 +854,14 @@ class Condition {
    * @param valueList the @a string with the new list of values.
    * @return the derived @a SimpleCondition instance, or NULL if the value list is invalid.
    */
-  virtual SimpleCondition* derive(string valueList) { return NULL; }
+  virtual SimpleCondition* derive(string valueList) const { return NULL; }
 
   /**
    * Write the condition definition or resolved expression to the @a ostream.
    * @param output the @a ostream to append to.
    * @param matched true for dumping the matched value if the condition is true, false for dumping the definition.
    */
-  virtual void dump(ostream& output, bool matched = false) = 0;
+  virtual void dump(ostream& output, bool matched = false) const = 0;
 
   /**
    * Combine this condition with another instance using a logical and.
@@ -931,10 +925,10 @@ class SimpleCondition : public Condition {
   virtual ~SimpleCondition() {}
 
   // @copydoc
-  SimpleCondition* derive(string valueList) override;
+  SimpleCondition* derive(string valueList) const override;
 
   // @copydoc
-  void dump(ostream& output, bool matched = false) override;
+  void dump(ostream& output, bool matched = false) const override;
 
   // @copydoc
   CombinedCondition* combineAnd(Condition* other) override;
@@ -950,7 +944,7 @@ class SimpleCondition : public Condition {
    * Return whether the condition is based on a numeric value.
    * @return whether the condition is based on a numeric value.
    */
-  virtual bool isNumeric() { return true; }
+  virtual bool isNumeric() const { return true; }
 
 
  protected:
@@ -1062,7 +1056,7 @@ class SimpleStringCondition : public SimpleCondition {
   virtual ~SimpleStringCondition() {}
 
   // @copydoc
-  bool isNumeric() override { return false; }
+  bool isNumeric() const override { return false; }
 
 
  protected:
@@ -1093,7 +1087,7 @@ class CombinedCondition : public Condition {
   virtual ~CombinedCondition() {}
 
   // @copydoc
-  void dump(ostream& output, bool matched = false) override;
+  void dump(ostream& output, bool matched = false) const override;
 
   // @copydoc
   CombinedCondition* combineAnd(Condition* other) override { m_conditions.push_back(other); return this; }
@@ -1124,7 +1118,7 @@ class Instruction {
    * executed for the same source file.
    * @param defaults the mapped definition defaults.
    */
-  Instruction(Condition* condition, const bool singleton, map<string, string>& defaults)
+  Instruction(Condition* condition, const bool singleton, const map<string, string>& defaults)
     : m_condition(condition), m_singleton(singleton), m_defaults(defaults) { }
 
   /**
@@ -1158,13 +1152,13 @@ class Instruction {
    * @return whether this @a Instruction belongs to a set of instructions of which only the first one may be executed
    * for the same source file.
    */
-  bool isSingleton() { return m_singleton; }
+  bool isSingleton() const { return m_singleton; }
 
   /**
    * Return a string describing the destination from the stored default values.
    * @return a string describing the destination.
    */
-  string getDestination();
+  string getDestination() const;
 
   /**
    * Execute the instruction.
@@ -1182,7 +1176,7 @@ class Instruction {
 
   /** whether this @a Instruction belongs to a set of instructions of which only the first one may be executed for the
    * same source file. */
-  bool m_singleton;
+  const bool m_singleton;
 
 
  protected:
@@ -1227,17 +1221,6 @@ class LoadInstruction : public Instruction {
  */
 class LoadedFileInfo {
  public:
-  /**
-   * Constructor.
-   * @param comment the optional comment for the file.
-   * @param hash the hash of the file.
-   * @param size the normalized size of the file.
-   * @param time the modification time of the file.
-   */
-  /*explicit LoadedFileInfo(string comment, size_t hash, size_t size, time_t time)
-      : m_comment(comment), m_hash(hash), m_size(size), m_time(time) {}
-  LoadedFileInfo(const LoadedFileInfo& copyFrom)
-      : m_comment(copyFrom.m_comment), m_hash(copyFrom.m_hash), m_size(copyFrom.m_size), m_time(copyFrom.m_time) {}*/
   /** the optional comment for the file. */
   string m_comment;
 
@@ -1293,7 +1276,7 @@ class MessageMap : public MappedFileReader {
   result_t add(Message* message, bool storeByName = true);
 
   // @copydoc
-  result_t getFieldMap(vector<string>& row, string& errorDescription) override;
+  result_t getFieldMap(vector<string>& row, string& errorDescription) const override;
 
   // @copydoc
   result_t addDefaultFromFile(map<string, string>& row, vector< map<string, string> >& subRows,
@@ -1311,7 +1294,7 @@ class MessageMap : public MappedFileReader {
 
   // @copydoc
   bool extractDefaultsFromFilename(string filename, map<string, string>& defaults,
-      symbol_t* destAddress = NULL, unsigned int* software = NULL, unsigned int* hardware = NULL) override;
+      symbol_t* destAddress = NULL, unsigned int* software = NULL, unsigned int* hardware = NULL) const override;
 
   // @copydoc
   result_t readFromFile(const string filename, string& errorDescription, bool verbose = false,
@@ -1332,7 +1315,7 @@ class MessageMap : public MappedFileReader {
    * Return whether additional scan @a Message instances are available.
    * @return whether additional scan @a Message instances are available.
    */
-  bool hasAdditionalScanMessages() { return m_additionalScanMessages; }
+  bool hasAdditionalScanMessages() const { return m_additionalScanMessages; }
 
   /**
    * Resolve all @a Condition instances.
@@ -1374,13 +1357,13 @@ class MessageMap : public MappedFileReader {
    * @param address the slave address.
    * @return the loaded configuration files (list of file names with relative path).
    */
-  vector<string>& getLoadedFiles(symbol_t address);
+  const vector<string>& getLoadedFiles(symbol_t address) const;
 
   /**
    * Get all loaded files.
    * @return the loaded configuration files (list of file names with relative path).
    */
-  vector<string> getLoadedFiles();
+  vector<string> getLoadedFiles() const;
 
   /**
    * Get the infos for a loaded file.
@@ -1392,7 +1375,7 @@ class MessageMap : public MappedFileReader {
    * @return true if the file info was found, false otherwise.
    */
   bool getLoadedFileInfo(string filename, string& comment, size_t* hash = NULL, size_t* size = NULL,
-      time_t* time = NULL);
+      time_t* time = NULL) const;
 
   /**
    * Get the stored @a Message instances for the key.
@@ -1400,7 +1383,7 @@ class MessageMap : public MappedFileReader {
    * @return the found @a Message instances, or NULL.
    * Note: the caller may not free the returned instances.
    */
-  vector<Message*>* getByKey(const uint64_t key);
+  const vector<Message*>* getByKey(const uint64_t key) const;
 
   /**
    * Find the @a Message instance for the specified circuit and name.
@@ -1413,7 +1396,7 @@ class MessageMap : public MappedFileReader {
    * Note: the caller may not free the returned instance.
    */
   Message* find(const string& circuit, const string& name, const string& levels, const bool isWrite,
-    const bool isPassive = false);
+    const bool isPassive = false) const;
 
   /**
    * Find all active get @a Message instances for the specified circuit and name.
@@ -1439,7 +1422,7 @@ class MessageMap : public MappedFileReader {
   deque<Message*> findAll(const string& circuit, const string& name, const string& levels,
     const bool completeMatch = true, const bool withRead = true, const bool withWrite = false,
     const bool withPassive = false, const bool includeEmptyLevel = true, const bool onlyAvailable = true,
-    const time_t since = 0, const time_t until = 0);
+    const time_t since = 0, const time_t until = 0) const;
 
   /**
    * Find the @a Message instance for the specified master data.
@@ -1454,7 +1437,7 @@ class MessageMap : public MappedFileReader {
    * Note: the caller may not free the returned instance.
    */
   Message* find(MasterSymbolString& master, bool anyDestination = false, const bool withRead = true,
-      const bool withWrite = true, const bool withPassive = true, const bool onlyAvailable = true);
+      const bool withWrite = true, const bool withPassive = true, const bool onlyAvailable = true) const;
 
   /**
    * Invalidate cached data of the @a Message and all other instances with a matching name key.
@@ -1478,25 +1461,25 @@ class MessageMap : public MappedFileReader {
    * Get the number of all stored @a Message instances.
    * @return the the number of all stored @a Message instances.
    */
-  size_t size() { return m_messageCount; }
+  size_t size() const { return m_messageCount; }
 
   /**
    * Get the number of stored conditional @a Message instances.
    * @return the the number of stored conditional @a Message instances.
    */
-  size_t sizeConditional() { return m_conditionalMessageCount; }
+  size_t sizeConditional() const { return m_conditionalMessageCount; }
 
   /**
    * Get the number of stored passive @a Message instances.
    * @return the the number of stored passive @a Message instances.
    */
-  size_t sizePassive() { return m_passiveMessageCount; }
+  size_t sizePassive() const { return m_passiveMessageCount; }
 
   /**
    * Get the number of stored @a Message instances with a poll priority.
    * @return the the number of stored @a Message instances with a poll priority.
    */
-  size_t sizePoll() { return m_pollMessages.size(); }
+  size_t sizePoll() const { return m_pollMessages.size(); }
 
   /**
    * Get the next @a Message to poll.
@@ -1509,23 +1492,26 @@ class MessageMap : public MappedFileReader {
    * Get the number of stored @a Condition instances.
    * @return the number of stored @a Condition instances.
    */
-  size_t sizeConditions() { return m_conditions.size(); }
+  size_t sizeConditions() const { return m_conditions.size(); }
 
   /**
    * Get the stored @a Condition instances.
    * @return the @a Condition instances by filename and condition name.
    */
-  map<string, Condition*>& getConditions() { return m_conditions; }
+  const map<string, Condition*>& getConditions() const { return m_conditions; }
 
   /**
    * Write the message definitions to the @a ostream.
    * @param output the @a ostream to append the formatted messages to.
    * @param withConditions whether to include the optional conditions prefix.
    */
-  void dump(ostream& output, bool withConditions = false);
+  void dump(ostream& output, const bool withConditions = false) const;
 
 
  private:
+  /** empty vector for @a getLoadedFiles(). */
+  static vector<string> s_noFiles;
+
   /** whether to add all messages, even if duplicate. */
   const bool m_addAll;
 

src/lib/ebus/symbol.cpp

@@ -144,7 +144,7 @@ result_t SymbolString::parseHexEscaped(const string& str) {
   return inEscape ? RESULT_ERR_ESC : RESULT_OK;
 }
 
-const string SymbolString::getStr(size_t skipFirstSymbols) {
+const string SymbolString::getStr(size_t skipFirstSymbols) const {
   ostringstream sstr;
   for (size_t i = 0; i < m_data.size(); i++) {
     if (skipFirstSymbols > 0) {

src/lib/ebus/symbol.h

@@ -156,7 +156,7 @@ class SymbolString {
    * @param skipFirstSymbols the number of first symbols to skip.
    * @return the symbols as hex string.
    */
-  const string getStr(size_t skipFirstSymbols = 0);
+  const string getStr(size_t skipFirstSymbols = 0) const;
 
   /**
    * Return a reference to the symbol at the specified index.
@@ -245,6 +245,19 @@ class SymbolString {
     return m_data.size() < lengthOffset + 1 + ret ? m_data.size() - lengthOffset - 1 : ret;
   }
 
+  /**
+   * Return the data byte at the specified index (within DD).
+   * @param index the index of the data byte (within DD) to return.
+   * @return the data byte at the specified index, or 0 if not available.
+   */
+  symbol_t dataAt(const size_t index) const {
+    size_t offset = (m_isMaster ? 5 : 1) + index;
+    if (offset < m_data.size()) {
+      return m_data[offset];
+    }
+    return 0;
+  }
+
   /**
    * Return a reference to the data byte at the specified index (within DD).
    * @param index the index of the data byte (within DD) to return.

src/lib/ebus/test/test_data.cpp

@@ -53,7 +53,7 @@ class TestReader : public MappedFileReader {
   TestReader(DataFieldTemplates* templates, bool isSet, bool isMasterDest)
   : MappedFileReader::MappedFileReader(true), m_templates(templates), m_isSet(isSet), m_isMasterDest(isMasterDest),
     m_fields(NULL) {}
-  result_t getFieldMap(vector<string>& row, string& errorDescription) override {
+  result_t getFieldMap(vector<string>& row, string& errorDescription) const override {
     if (row.empty()) {
       row.push_back("*name");
       row.push_back("part");
@@ -84,7 +84,7 @@ class TestReader : public MappedFileReader {
   const bool m_isSet;
   const bool m_isMasterDest;
  public:
-  DataField* m_fields;
+  const DataField* m_fields;
 };
 
 
@@ -509,7 +509,7 @@ int main() {
   string errorDescription;
   vector<string> row;
   templates->readLineFromStream(dummystr, errorDescription, "inline", lineNo, row);
-  DataField* fields = NULL;
+  const DataField* fields = NULL;
   for (size_t i = 0; i < sizeof(checks) / sizeof(checks[0]); i++) {
     string check[5] = checks[i];
     istringstream isstr(check[0]);

src/lib/ebus/test/test_filereader.cpp

@@ -82,7 +82,7 @@ class NoopReader : public FileReader {
 class TestReader : public MappedFileReader {
  public:
   TestReader(size_t expectedCols) : MappedFileReader::MappedFileReader(false), m_expectedCols(expectedCols) {}
-  result_t getFieldMap(vector<string>& row, string& errorDescription) override {
+  result_t getFieldMap(vector<string>& row, string& errorDescription) const override {
     if (row.size() == m_expectedCols) {
       cout << "get field map: split OK" << endl;
       return RESULT_OK;