added support for conditions based on raw value of numeric fields, adjust error position cout in case of duplicate, corrected getDefault() size check

src/lib/ebus/message.cpp

@@ -27,22 +27,29 @@
 #include <algorithm>
 #include <locale>
 #include <iomanip>
+#include <climits>
 
 using namespace std;
 
 /** the bit mask of the source master number in the message key. */
 #define ID_SOURCE_MASK (0x1fLL << (8 * 7))
 
+/** the maximum poll priority for a @a Message referred to by a @a Condition. */
+#define POLL_PRIORITY_CONDITION 5
+
 Message::Message(const string circuit, const string name, const bool isWrite,
 		const bool isPassive, const string comment,
 		const unsigned char srcAddress, const unsigned char dstAddress,
-		const vector<unsigned char> id, DataField* data, const bool deleteData,
+		const vector<unsigned char> id,
-		const unsigned char pollPriority)
+		DataField* data, const bool deleteData,
+		const unsigned char pollPriority,
+		Condition* condition)
 		: m_circuit(circuit), m_name(name), m_isWrite(isWrite),
 		  m_isPassive(isPassive), m_comment(comment),
 		  m_srcAddress(srcAddress), m_dstAddress(dstAddress),
 		  m_id(id), m_data(data), m_deleteData(deleteData),
 		  m_pollPriority(pollPriority),
+		  m_usedByCondition(false), m_condition(condition),
 		  m_lastUpdateTime(0), m_lastChangeTime(0), m_pollCount(0), m_lastPollTime(0)
 {
 	int exp = 7;
@@ -59,11 +66,14 @@ Message::Message(const string circuit, const string name, const bool isWrite,
 
 Message::Message(const bool isWrite, const bool isPassive,
 		const unsigned char pb, const unsigned char sb,
-		DataField* data)
+		DataField* data,
+		Condition* condition)
 		: m_circuit(), m_name(), m_isWrite(isWrite),
 		  m_isPassive(isPassive), m_comment(),
 		  m_srcAddress(SYN), m_dstAddress(SYN),
-		  m_data(data), m_deleteData(true), m_pollPriority(0),
+		  m_data(data), m_deleteData(true),
+		  m_pollPriority(0),
+		  m_usedByCondition(false), m_condition(condition),
 		  m_lastUpdateTime(0), m_lastChangeTime(0), m_pollCount(0), m_lastPollTime(0)
 {
 	m_id.push_back(pb);
@@ -80,7 +90,7 @@ Message::Message(const bool isWrite, const bool isPassive,
  */
 string getDefault(const string value, vector<string>* defaults, size_t pos)
 {
-	if (value.length() > 0 || defaults == NULL || pos > defaults->size()) {
+	if (value.length() > 0 || defaults == NULL || pos >= defaults->size()) {
 		return value;
 	}
 
@@ -88,7 +98,7 @@ string getDefault(const string value, vector<string>* defaults, size_t pos)
 }
 
 result_t Message::create(vector<string>::iterator& it, const vector<string>::iterator end,
-		vector< vector<string> >* defaultsRows,
+		vector< vector<string> >* defaultsRows, map<string, Condition*>* conditions, const string& filename,
 		DataFieldTemplates* templates, vector<Message*>& messages)
 {
 	// [type],[circuit],name,[comment],[QQ[;QQ]*],[ZZ],[PBSB],[ID],fields...
@@ -100,7 +110,23 @@ result_t Message::create(vector<string>::iterator& it, const vector<string>::ite
 	if (it == end)
 		return RESULT_ERR_EOF;
 
-	const char* str = (*it++).c_str(); // [type]
+	string typeStr = *it++;
+	Condition* condition = NULL;
+	if (conditions && typeStr.length()>0 && typeStr[0]=='[') {
+		// condition
+		size_t pos = typeStr.find(']');
+		if (pos!=string::npos) {
+			string type = typeStr.substr(1, pos-1);
+			string key = filename+":"+type;
+			map<string, Condition*>::iterator it = conditions->find(key);
+			if (it==conditions->end())
+				return RESULT_ERR_NOTFOUND;
+			condition = it->second;
+			typeStr = typeStr.substr(pos+1);
+		}
+	}
+
+	const char* str = typeStr.c_str(); // [type]
 	if (it == end)
 		return RESULT_ERR_EOF;
 	size_t len = strlen(str);
@@ -278,7 +304,7 @@ result_t Message::create(vector<string>::iterator& it, const vector<string>::ite
 			sprintf(num, ".%d", index);
 			useCircuit = useCircuit + num;
 		}
-		messages.push_back(new Message(useCircuit, name, isWrite, isPassive, comment, srcAddress, dstAddress, id, data, index==0, pollPriority));
+		messages.push_back(new Message(useCircuit, name, isWrite, isPassive, comment, srcAddress, dstAddress, id, data, index==0, pollPriority, condition));
 	}
 	return RESULT_OK;
 }
@@ -288,8 +314,30 @@ bool Message::setPollPriority(unsigned char priority)
 	if (priority == m_pollPriority || m_isPassive)
 		return false;
 
+	if (m_usedByCondition && (priority==0 || priority>POLL_PRIORITY_CONDITION))
+		priority = POLL_PRIORITY_CONDITION;
+
+	bool ret = m_pollPriority==0 && priority>0;
 	m_pollPriority = priority;
-	return true;
+	return ret;
+}
+
+void Message::setUsedByCondition() {
+	if (m_usedByCondition)
+		return;
+	m_usedByCondition = true;
+	if (m_pollPriority==0 || m_pollPriority>POLL_PRIORITY_CONDITION)
+		setPollPriority(POLL_PRIORITY_CONDITION);
+}
+
+bool Message::isAvailable()
+{
+	return (m_condition==NULL) || m_condition->isTrue();
+}
+
+bool Message::hasField(const char* fieldName, bool numeric)
+{
+	return m_data->hasField(fieldName, numeric);
 }
 
 result_t Message::prepareMaster(const unsigned char srcAddress, SymbolString& masterData, istringstream& input, char separator, const unsigned char dstAddress)
@@ -455,17 +503,34 @@ result_t Message::decodeLastData(ostringstream& output, OutputFormat outputForma
 	return result;
 }
 
+result_t Message::decodeLastDataField(unsigned int& output, const char* fieldName, signed char fieldIndex)
+{
+	unsigned char offset = (unsigned char)(m_id.size() - 2);
+	result_t result = m_data->read(pt_masterData, m_lastMasterData, offset, output, fieldName, fieldIndex);
+	if (result < RESULT_OK)
+		return result;
+	if (result == RESULT_EMPTY)
+		result = m_data->read(pt_slaveData, m_lastSlaveData, 0, output, fieldName, fieldIndex);
+	if (result < RESULT_OK)
+		return result;
+	if (result == RESULT_EMPTY)
+		return RESULT_ERR_NOTFOUND;
+	return result;
+}
+
 bool Message::isLessPollWeight(const Message* other)
 {
-	unsigned int tw = m_pollPriority * m_pollCount;
+	unsigned char tprio = m_pollPriority;
-	unsigned int ow = other->m_pollPriority * other->m_pollCount;
+	unsigned char oprio = other->m_pollPriority;
+	unsigned int tw = tprio * m_pollCount;
+	unsigned int ow = oprio * other->m_pollCount;
 	if (tw > ow)
 		return true;
 	if (tw < ow)
 		return false;
-	if (m_pollPriority > other->m_pollPriority)
+	if (tprio > oprio)
 		return true;
-	if (m_pollPriority < other->m_pollPriority)
+	if (tprio < oprio)
 		return false;
 	if (m_lastPollTime > other->m_lastPollTime)
 		return true;
@@ -577,44 +642,191 @@ string strtolower(const string& str)
 	return ret;
 }
 
+
+
+result_t Condition::create(vector<string>::iterator& it, const vector<string>::iterator end, Condition*& returnValue)
+{
+	if (it==end)
+		return RESULT_ERR_EOF;
+	string circuit = *(it++);
+	if (circuit.length()==0)
+		return RESULT_ERR_INVALID_ARG;
+	if (it==end)
+		return RESULT_ERR_EOF;
+	string name = *(it++);
+	if (name.length()==0)
+		return RESULT_ERR_INVALID_ARG;
+	if (it==end)
+		return RESULT_ERR_EOF;
+	string field = *(it++);
+
+	istringstream stream(*(it++));
+	string str;
+	vector<unsigned int> valueRanges;
+	result_t result;
+	while (getline(stream, str, VALUE_SEPARATOR) != 0) {
+		DataFieldTemplates::trim(str);
+		if (str.length()==0)
+			return RESULT_ERR_INVALID_ARG;
+		bool upto = str[0]=='<';
+		if (upto || str[0]=='>') {
+			if (str.length()==1)
+				return RESULT_ERR_INVALID_ARG;
+			if (upto)
+				valueRanges.push_back(0);
+			bool inclusive = str[1]=='=';
+			unsigned int val = parseInt(str.substr(inclusive?2:1).c_str(), 10, 0, UINT_MAX, result);
+			if (result!=RESULT_OK)
+				return result;
+			valueRanges.push_back(inclusive ? val : (val+(upto?-1:1)));
+			if (!upto)
+				valueRanges.push_back(UINT_MAX);
+		} else {
+			size_t pos = str.find('-');
+			if (pos>0) { // range
+				unsigned int val = parseInt(str.substr(0, pos).c_str(), 10, 0, UINT_MAX, result);
+				if (result!=RESULT_OK)
+					return result;
+				valueRanges.push_back(val);
+				pos++;
+			} else { // single value
+				pos = 0;
+			}
+			unsigned int val = parseInt(str.substr(pos).c_str(), 10, 0, UINT_MAX, result);
+			if (result!=RESULT_OK)
+				return result;
+			valueRanges.push_back(val);
+			if (pos>0)
+				valueRanges.push_back(val); // single value
+		}
+	}
+	if (valueRanges.empty())
+		return RESULT_ERR_INVALID_LIST;
+
+	returnValue = new Condition(circuit, name, field, valueRanges);
+	return RESULT_OK;
+}
+
+result_t Condition::resolve(MessageMap* messages, ostringstream& errorMessage)
+{
+	Message* message = messages->find(m_circuit, m_name, false);
+	if (!message)
+		message = messages->find(m_circuit, m_name, false, true);
+	if (!message) {
+		errorMessage << "condition " << m_circuit << " " << m_name << ": message not found";
+		return RESULT_ERR_NOTFOUND;
+	}
+	if (m_field.length()>0) {
+		if (!message->hasField(m_field.c_str(), true)) {
+			errorMessage << "condition " << m_circuit << " " << m_name << ": numeric field " << m_field << " not found";
+			return RESULT_ERR_NOTFOUND;
+		}
+	}
+	m_message = message;
+	return RESULT_OK;
+}
+
+bool Condition::isTrue()
+{
+	if (!m_message)
+		return false;
+	if (m_message->getLastChangeTime()>m_lastCheckTime) {
+		unsigned int value = 0;
+		result_t result = m_message->decodeLastDataField(value, m_field.length()==0 ? NULL : m_field.c_str());
+		bool isTrue = false;
+		if (result==RESULT_OK) {
+			for (size_t i=0; i+1<m_valueRanges.size(); i+=2) {
+				if (m_valueRanges[i]<=value && value<=m_valueRanges[i+1]) {
+					isTrue = true;
+					break;
+				}
+			}
+		}
+		m_isTrue = isTrue;
+		m_lastCheckTime = m_message->getLastChangeTime();
+	}
+	return m_isTrue;
+}
+
+
 result_t MessageMap::add(Message* message)
 {
 	unsigned long long key = message->getKey();
-	map<unsigned long long, Message*>::iterator keyIt = m_messagesByKey.find(key);
+	bool conditional = message->isConditional();
-	if (keyIt != m_messagesByKey.end())
+	map<unsigned long long, vector<Message*> >::iterator keyIt = m_messagesByKey.find(key);
-		return RESULT_ERR_DUPLICATE; // duplicate key
+	if (keyIt != m_messagesByKey.end()) {
-
+		vector<Message*>* messages = &keyIt->second;
+		if (!messages->front()->isConditional() || !conditional)
+			return RESULT_ERR_DUPLICATE; // duplicate key
+	}
 	bool isPassive = message->isPassive();
 	bool isWrite = message->isWrite();
 	string circuit = strtolower(message->getCircuit());
 	string name = strtolower(message->getName());
 	string nameKey = string(isPassive ? "P" : (isWrite ? "W" : "R")) + circuit + FIELD_SEPARATOR + name;
-	map<string, Message*>::iterator nameIt = m_messagesByName.find(nameKey);
+	map<string, vector<Message*> >::iterator nameIt = m_messagesByName.find(nameKey);
-	if (nameIt != m_messagesByName.end())
+	if (nameIt != m_messagesByName.end()) {
-		return RESULT_ERR_DUPLICATE; // duplicate key
+		vector<Message*>* messages = &nameIt->second;
-
+		if (!messages->front()->isConditional() || !message->isConditional())
-	m_messagesByName[nameKey] = message;
+			return RESULT_ERR_DUPLICATE_NAME; // duplicate key
+	}
+	m_messagesByName[nameKey].push_back(message);
 	m_messageCount++;
+	if (conditional)
+		m_conditionalMessageCount++;
 	if (isPassive)
 		m_passiveMessageCount++;
 
 	nameKey = string(isPassive ? "-P" : (isWrite ? "-W" : "-R")) + name; // also store without circuit
 	nameIt = m_messagesByName.find(nameKey);
 	if (nameIt == m_messagesByName.end())
-		m_messagesByName[nameKey] = message; // only store first key without circuit
+		m_messagesByName[nameKey].push_back(message); // always store first message without circuit
-
+	else {
+		vector<Message*>* messages = &nameIt->second;
+		if (messages->front()->isConditional() && conditional)
+			m_messagesByName[nameKey].push_back(message); // store further messages only if both are conditional
+	}
 	unsigned char idLength = (unsigned char)(message->getId().size() - 2);
 	if (idLength < m_minIdLength)
 		m_minIdLength = idLength;
 	if (idLength > m_maxIdLength)
 		m_maxIdLength = idLength;
-	m_messagesByKey[key] = message;
+	m_messagesByKey[key].push_back(message);
 
 	addPollMessage(message);
 
 	return RESULT_OK;
 }
 
+result_t MessageMap::addDefaultFromFile(vector< vector<string> >& defaults, vector<string>& row, vector<string>::iterator& begin, const string& filename, unsigned int lineNo)
+{
+	// convert conditions in defaults
+	string type = row[0];
+	if (type.length()>0 && type[0]=='[' && type[type.length()-1]==']') {
+		// condition
+		type.erase(0, 1);
+		type.resize(type.length()-1);
+		string key = filename+":"+type;
+		map<string, Condition*>::iterator it = m_conditions.find(key);
+		if (it != m_conditions.end())
+			return RESULT_ERR_DUPLICATE_NAME;
+
+		Condition* condition = NULL;
+		result_t result = Condition::create(++begin, row.end(), condition);
+		if (result!=RESULT_OK) {
+			if (condition)
+				delete condition;
+			return result;
+		}
+		if (!condition)
+			return RESULT_ERR_INVALID_ARG;
+
+		m_conditions[key] = condition;
+		return RESULT_OK;
+	}
+	return FileReader::addDefaultFromFile(defaults, row, begin, filename, lineNo);
+}
+
 result_t MessageMap::addFromFile(vector<string>::iterator& begin, const vector<string>::iterator end, DataFieldTemplates* arg, vector< vector<string> >* defaults, const string& filename, unsigned int lineNo)
 {
 	vector<string>::iterator restart = begin;
@@ -631,11 +843,16 @@ result_t MessageMap::addFromFile(vector<string>::iterator& begin, const vector<s
 		*restart = type;
 		begin = restart;
 		messages.clear();
-		result = Message::create(begin, end, defaults, arg, messages);
+		result = Message::create(begin, end, defaults, &m_conditions, filename, arg, messages);
 		for (vector<Message*>::iterator it = messages.begin(); it != messages.end(); it++) {
 			Message* message = *it;
-			if (result == RESULT_OK)
+			if (result == RESULT_OK) {
 				result = add(message);
+				if (result==RESULT_ERR_DUPLICATE_NAME)
+					begin = restart+3; // mark name as invalid
+				else if (result==RESULT_ERR_DUPLICATE)
+					begin = restart+8; // mark ID as invalid
+			}
 			if (result != RESULT_OK)
 				delete message; // delete all remaining messages on error
 		}
@@ -646,6 +863,37 @@ result_t MessageMap::addFromFile(vector<string>::iterator& begin, const vector<s
 	return result;
 }
 
+result_t MessageMap::resolveConditions(string& errorMessage, bool verbose) {
+	result_t overallResult = RESULT_OK;
+	ostringstream error;
+	for (map<string, Condition*>::iterator it = m_conditions.begin(); it != m_conditions.end(); it++) {
+		Condition* condition = it->second;
+		result_t result = condition->resolve(this, error);
+		if (result!=RESULT_OK) {
+			if (verbose) {
+				overallResult = result;
+				error << ", ";
+			} else {
+				errorMessage = error.str();
+				return result;
+			}
+		} else {
+			Message* message = condition->getMessage();
+			message->setUsedByCondition();
+			addPollMessage(message, true);
+		}
+	}
+	errorMessage = error.str();
+	return overallResult;
+}
+
+Message* getFirstAvailable(vector<Message*> &messages) {
+	for (vector<Message*>::iterator msgIt = messages.begin(); msgIt != messages.end(); msgIt++)
+		if ((*msgIt)->isAvailable())
+			return *msgIt;
+	return NULL;
+}
+
 Message* MessageMap::find(const string& circuit, const string& name, const bool isWrite, const bool isPassive)
 {
 	string lcircuit = strtolower(circuit);
@@ -658,9 +906,12 @@ Message* MessageMap::find(const string& circuit, const string& name, const bool
 			key = string(isPassive ? "-P" : (isWrite ? "-W" : "-R")) + lname; // second try: without circuit
 		else
 			continue; // not allowed without circuit
-		map<string, Message*>::iterator it = m_messagesByName.find(key);
+		map<string, vector<Message*> >::iterator it = m_messagesByName.find(key);
-		if (it != m_messagesByName.end())
+		if (it != m_messagesByName.end()) {
-			return it->second;
+			Message* message = getFirstAvailable(it->second);
+			if (message)
+				return message;
+		}
 	}
 
 	return NULL;
@@ -676,10 +927,12 @@ deque<Message*> MessageMap::findAll(const string& circuit, const string& name, c
 	bool checkCircuit = lcircuit.length() > 0;
 	bool checkName = name.length() > 0;
 	bool checkPb = pb >= 0;
-	for (map<string, Message*>::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
+	for (map<string, vector<Message*> >::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
 		if (it->first[0] == '-') // avoid duplicates: instances stored multiple times have a key starting with "-"
 			continue;
-		Message* message = it->second;
+		Message* message = getFirstAvailable(it->second);
+		if (!message)
+			continue;
 		if (checkCircuit) {
 			string check = strtolower(message->getCircuit());
 			if (completeMatch ? (check != lcircuit) : (check.find(lcircuit) == check.npos))
@@ -741,18 +994,26 @@ deque<Message*> MessageMap::findAll(SymbolString& master)
 		for (unsigned char i = 0; i < idLength; i++)
 			key |= (unsigned long long)master[5 + i] << (8 * exp--);
 
-		map<unsigned long long , Message*>::iterator it = m_messagesByKey.find(key);
+		map<unsigned long long , vector<Message*> >::iterator it = m_messagesByKey.find(key);
 		if (it != m_messagesByKey.end()) {
-			ret.push_back(it->second);
+			Message* message = getFirstAvailable(it->second);
+			if (message)
+				ret.push_back(message);
 		}
 		if ((key & ID_SOURCE_MASK) != 0) {
 			it = m_messagesByKey.find(key & ~ID_SOURCE_MASK); // try again without specific source master
-			if (it != m_messagesByKey.end())
+			if (it != m_messagesByKey.end()) {
-				ret.push_back(it->second);
+				Message* message = getFirstAvailable(it->second);
+				if (message)
+					ret.push_back(message);
+			}
 		}
 		it = m_messagesByKey.find(key | ID_SOURCE_MASK); // try again with special value for active
-		if (it != m_messagesByKey.end())
+		if (it != m_messagesByKey.end()) {
-			ret.push_back(it->second);
+			Message* message = getFirstAvailable(it->second);
+			if (message)
+				ret.push_back(message);
+		}
 	}
 
 	return ret;
@@ -785,10 +1046,10 @@ void MessageMap::invalidateCache(Message* message)
 	}
 }
 
-void MessageMap::addPollMessage(Message* message)
+void MessageMap::addPollMessage(Message* message, bool toFront)
 {
 	if (message != NULL && message->getPollPriority() > 0) {
-		message->m_lastPollTime = m_pollMessages.size();
+		message->m_lastPollTime = toFront ? 0 : m_pollMessages.size();
 		m_pollMessages.push(message);
 	}
 }
@@ -801,17 +1062,18 @@ void MessageMap::clear()
 		m_pollMessages.pop();
 	}
 	// free message instances
-	for (map<string, Message*>::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
+	for (map<string, vector<Message*> >::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
 		if (it->first[0] != '-') // avoid double free: instances stored multiple times have a key starting with "-"
-			delete it->second;
+			it->second.clear();
-		it->second = NULL;
 	}
 	// clear messages by name
 	m_messageCount = 0;
+	m_conditionalMessageCount = 0;
 	m_passiveMessageCount = 0;
 	m_messagesByName.clear();
 	// clear messages by key
 	m_messagesByKey.clear();
+	m_conditions.clear();
 	m_minIdLength = 4;
 	m_maxIdLength = 0;
 }
@@ -831,16 +1093,18 @@ Message* MessageMap::getNextPoll()
 void MessageMap::dump(ostream& output)
 {
 	bool first = true;
-	for (map<string, Message*>::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
+	for (map<string, vector<Message*> >::iterator it = m_messagesByName.begin(); it != m_messagesByName.end(); it++) {
 		if (it->first[0] == '-') // skip instances stored multiple times (key starting with "-")
 			continue;
-		Message* message = it->second;
+		Message* message = getFirstAvailable(it->second);
+		if (!message)
+			continue;
 		if (first)
 			first = false;
 		else
-			cout << endl;
+			output << endl;
-		message->dump(cout);
+		message->dump(output);
 	}
 	if (!first)
-		cout << endl;
+		output << endl;
 }

src/lib/ebus/message.h

@@ -32,6 +32,7 @@
 
 using namespace std;
 
+class Condition;
 class MessageMap;
 
 /**
@@ -56,12 +57,15 @@ public:
 	 * @param data the @a DataField for encoding/decoding the message.
 	 * @param deleteData whether to delete the @a DataField during destruction.
 	 * @param pollPriority the priority for polling, or 0 for no polling at all.
+	 * @param condition the @a Condition for this message, or NULL.
 	 */
 	Message(const string circuit, const string name, const bool isWrite,
 			const bool isPassive, const string comment,
 			const unsigned char srcAddress, const unsigned char dstAddress,
-			const vector<unsigned char> id, DataField* data, const bool deleteData,
+			const vector<unsigned char> id,
-			const unsigned char pollPriority);
+			DataField* data, const bool deleteData,
+			const unsigned char pollPriority,
+			Condition* condition=NULL);
 
 	/**
 	 * Construct a new temporary instance.
@@ -71,10 +75,12 @@ public:
 	 * @param pb the primary ID byte.
 	 * @param sb the secondary ID byte.
 	 * @param data the @a DataField for encoding/decoding the message.
+	 * @param condition the @a Condition for this message, or NULL.
 	 */
 	Message(const bool isWrite, const bool isPassive,
 			const unsigned char pb, const unsigned char sb,
-			DataField* data);
+			DataField* data,
+			Condition* condition=NULL);
 
 	/**
 	 * Destructor.
@@ -86,13 +92,15 @@ public:
 	 * @param it the iterator to traverse for the definition parts.
 	 * @param end the iterator pointing to the end of the definition parts.
 	 * @param defaultsRows a @a vector with rows containing defaults, or NULL.
+	 * @param conditions the @a Condition instances by filename and condition name, or NULL.
+	 * @param filename the name of the file being read.
 	 * @param templates the @a DataFieldTemplates to be referenced by name, or NULL.
 	 * @param messages the @a vector to which to add created instances.
 	 * @return @a RESULT_OK on success, or an error code.
 	 * Note: the caller needs to free the created instances.
 	 */
 	static result_t create(vector<string>::iterator& it, const vector<string>::iterator end,
-			vector< vector<string> >* defaultsRows,
+			vector< vector<string> >* defaultsRows, map<string, Condition*>* conditions, const string& filename,
 			DataFieldTemplates* templates, vector<Message*>& messages);
 
 	/**
@@ -159,10 +167,35 @@ public:
 	/**
 	 * Set the polling priority.
 	 * @param priority the polling priority, or 0 for no polling at all.
-	 * @return true when the priority was changed, false otherwise.
+	 * @return true when the priority was changed and polling was not enabled before, false otherwise.
 	 */
 	bool setPollPriority(unsigned char priority);
 
+	/**
+	 * Set the poll priority suitable for resolving a @a Condition.
+	 */
+	void setUsedByCondition();
+
+	/**
+	 * Return whether this @a Message depends on a @a Condition.
+	 * @return true when this @a Message depends on a @a Condition.
+	 */
+	bool isConditional() const { return m_condition!=NULL; }
+
+	/**
+	 * Return whether this @a Message is available (optionally depending on a @a Condition evaluation).
+	 * @return true when this @a Message is available.
+	 */
+	bool isAvailable();
+
+	/**
+	 * Return whether the field is available.
+	 * @param fieldName the name of the field to find.
+	 * @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);
+
 	/**
 	 * Prepare the master @a SymbolString for sending a query or command to the bus.
 	 * @param srcAddress the source address to set.
@@ -223,6 +256,15 @@ public:
 	result_t decodeLastData(ostringstream& output, OutputFormat outputFormat=0,
 			bool leadingSeparator=false, const char* fieldName=NULL, signed char fieldIndex=-1);
 
+	/**
+	 * Decode a particular field value from the last stored data.
+	 * @param output the variable in which to store the value.
+	 * @param fieldName the name of the field to decode, or NULL for the first field.
+	 * @param fieldIndex the optional index of the named field, or -1.
+	 * @return @a RESULT_OK on success, or an error code.
+	 */
+	result_t decodeLastDataField(unsigned int& output, const char* fieldName, signed char fieldIndex=-1);
+
 	/**
 	 * Get the last seen slave data.
 	 * @return the last seen slave @a SymbolString.
@@ -306,6 +348,12 @@ private:
 	/** the priority for polling, or 0 for no polling at all. */
 	unsigned char m_pollPriority;
 
+	/** whether this message is used by a @a Condition. */
+	bool m_usedByCondition;
+
+	/** the @a Condition for this message, or NULL. */
+	Condition* m_condition;
+
 	/** the last seen master data. */
 	SymbolString m_lastMasterData;
 
@@ -341,6 +389,110 @@ struct compareMessagePriority : binary_function <Message*,Message*,bool> {
 };
 
 
+/**
+ * Helper class extending @a priority_queue to hold distinct values only.
+ */
+class MessagePriorityQueue
+	: public priority_queue<Message*, vector<Message*>, compareMessagePriority>
+{
+public:
+	/**
+	 * Add data to the queue and ensure it is contained only once.
+	 * @param __x the element to add.
+	 */
+	void push(const value_type& __x)
+	{
+		for (vector<Message*>::iterator it = c.begin(); it != c.end(); it++) {
+			if (*it==__x) {
+				c.erase(it);
+				break;
+			}
+		}
+		priority_queue<Message*, vector<Message*>, compareMessagePriority>::push(__x);
+	}
+};
+
+
+/**
+ * Holds a reference to a @a Message as condition for another @a Message.
+ */
+class Condition
+{
+public:
+
+	/**
+	 * Construct a new instance.
+	 * @param circuit the circuit name.
+	 * @param name the message name.
+	 * @param field the field name.
+	 * @param valueRanges the valid value ranges (pairs of from/to inclusive).
+	 */
+	Condition(const string circuit, const string name, const string field, const vector<unsigned int> valueRanges)
+		: m_circuit(circuit), m_name(name), m_field(field), m_valueRanges(valueRanges),
+		  m_message(NULL), m_lastCheckTime(0), m_isTrue(false) {
+//		cout << "condition " << circuit << " " << name << " " << field << ":" << static_cast<unsigned>(valueRanges.size()) << endl;
+	}
+
+	/**
+	 * Destructor.
+	 */
+	virtual ~Condition() { }
+
+	/**
+	 * Factory method for creating a new instance.
+	 * @param it the iterator to traverse for the definition parts.
+	 * @param end the iterator pointing to the end of the definition parts.
+	 * @param returnValue the variable in which to store the created instance.
+	 * @return @a RESULT_OK on success, or an error code.
+	 */
+	static result_t create(vector<string>::iterator& it, const vector<string>::iterator end, Condition*& returnValue);
+
+	/**
+	 * Resolve the referred @a Message instance and field index.
+	 * @param messages the @a MessageMap instance for resolving the referred @a Message.
+	 * @param errorMessage a @a ostringstream to which to add optional error messages.
+	 * @return @a RESULT_OK on success, or an error code.
+	 */
+	result_t resolve(MessageMap* messages, ostringstream& errorMessage);
+
+	/**
+	 * Get the resolved @a Message instance
+	 * @return the resolved @a Message instance, or NULL.
+	 */
+	Message* getMessage() { return m_message; }
+
+	/**
+	 * Check and return whether this condition is fulfilled.
+	 * @return whether this condition is fulfilled.
+	 */
+	bool isTrue();
+
+private:
+
+	/** the circuit name. */
+	const string m_circuit;
+
+	/** the message name. */
+	const string m_name;
+
+	/** the field name, or empty for first field. */
+	const string m_field;
+
+	/** the valid value ranges (pairs of from/to inclusive). */
+	const vector<unsigned int> m_valueRanges;
+
+	/** the resolved @a Message instance, or NULL. */
+	Message* m_message;
+
+	/** the system time when the condition was last checked, 0 for never. */
+	time_t m_lastCheckTime;
+
+	/** whether the condition was @a true during the last check. */
+	bool m_isTrue;
+
+};
+
+
 /**
  * Holds a map of all known @a Message instances.
  */
@@ -352,7 +504,7 @@ public:
 	 * Construct a new instance.
 	 */
 	MessageMap() : FileReader<DataFieldTemplates*>::FileReader(true),
-		m_minIdLength(4), m_maxIdLength(0), m_messageCount(0), m_passiveMessageCount(0) {}
+		m_minIdLength(4), m_maxIdLength(0), m_messageCount(0), m_conditionalMessageCount(0), m_passiveMessageCount(0) {}
 
 	/**
 	 * Destructor.
@@ -367,9 +519,20 @@ public:
 	 */
 	result_t add(Message* message);
 
+	// @copydoc
+	virtual result_t addDefaultFromFile(vector< vector<string> >& defaults, vector<string>& row, vector<string>::iterator& begin, const string& filename, unsigned int lineNo);
+
 	// @copydoc
 	virtual result_t addFromFile(vector<string>::iterator& begin, const vector<string>::iterator end, DataFieldTemplates* arg, vector< vector<string> >* defaults, const string& filename, unsigned int lineNo);
 
+	/**
+	 * Resolve all @a Condition instances.
+	 * @param errorMessage a @a string reference to which to add an optional error message.
+	 * @param verbose whether to verbosely add all problems to the error message.
+	 * @return @a RESULT_OK on success, or an error code.
+	 */
+	result_t resolveConditions(string& errorMessage, bool verbose=false);
+
 	/**
 	 * Find the @a Message instance for the specified circuit and name.
 	 * @param circuit the optional circuit name.
@@ -421,8 +584,9 @@ public:
 	/**
 	 * Add a @a Message to the list of instances to poll.
 	 * @param message the @a Message to poll.
+	 * @param toFront whether to add the @a Message to the very front of the poll queue.
 	 */
-	void addPollMessage(Message* message);
+	void addPollMessage(Message* message, bool toFront=false);
 
 	/**
 	 * Removes all @a Message instances.
@@ -430,11 +594,22 @@ public:
 	void clear();
 
 	/**
-	 * Get the number of stored @a Message instances.
+	 * Get the number of all stored @a Message instances.
-	 * @param passiveOnly true to count only passive messages, false to count all messages.
+	 * @return the the number of all stored @a Message instances.
-	 * @return the the number of stored @a Message instances.
 	 */
-	size_t size(const bool passiveOnly=false) { return passiveOnly ? m_passiveMessageCount : m_messageCount; }
+	size_t size() { 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; }
+
+	/**
+	 * 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; }
 
 	/**
 	 * Get the number of stored @a Message instances with a poll priority.
@@ -449,6 +624,18 @@ public:
 	 */
 	Message* getNextPoll();
 
+	/**
+	 * Get the number of stored @a Condition instances.
+	 * @return the number of stored @a Condition instances.
+	 */
+	size_t sizeConditions() { 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; }
+
 	/**
 	 * Write the message definitions to the @a ostream.
 	 * @param output the @a ostream to append the formatted messages to.
@@ -466,17 +653,23 @@ private:
 	/** the number of distinct @a Message instances stored in @a m_messagesByName. */
 	size_t m_messageCount;
 
+	/** the number of conditional @a Message instances part of @a m_messageCount. */
+	size_t m_conditionalMessageCount;
+
 	/** the number of distinct passive @a Message instances stored in @a m_messagesByKey. */
 	size_t m_passiveMessageCount;
 
 	/** the known @a Message instances by lowercase circuit and name. */
-	map<string, Message*> m_messagesByName;
+	map<string, vector<Message*> > m_messagesByName;
 
 	/** the known @a Message instances by key. */
-	map<unsigned long long, Message*> m_messagesByKey;
+	map<unsigned long long, vector<Message*> > m_messagesByKey;
 
 	/** the known @a Message instances to poll, by priority. */
-	priority_queue<Message*, vector<Message*>, compareMessagePriority> m_pollMessages;
+	MessagePriorityQueue m_pollMessages;
+
+	/** the @a Condition instances by filename and condition name. */
+	map<string, Condition*> m_conditions;
 
 };