Airline group functions

src/blackmisc/simulation/aircraftmodellist.cpp

@@ -1131,6 +1131,30 @@ namespace BlackMisc
             return designators;
         }
 
+        CAirlineIcaoCodeList CAircraftModelList::getAirlineIcaoCodesForGroup(int groupId) const
+        {
+            if (groupId < 0) { return {}; }
+            CAirlineIcaoCodeList icaos;
+            for (const CAircraftModel &model : *this)
+            {
+                if (model.getAirlineIcaoCode().getGroupId() == groupId)
+                {
+                    icaos.push_back(model.getAirlineIcaoCode());
+                }
+            }
+            return icaos;
+        }
+
+        QSet<QString> CAircraftModelList::getAirlineDesignatorsForGroup(int groupId) const
+        {
+            return this->getAirlineIcaoCodesForGroup(groupId).allDesignators();
+        }
+
+        QSet<QString> CAircraftModelList::getAirlineVDesignatorsForGroup(int groupId) const
+        {
+            return this->getAirlineIcaoCodesForGroup(groupId).allVDesignators();
+        }
+
         QSet<QString> CAircraftModelList::getCombinedTypes() const
         {
             QSet<QString> combinedCodes;

src/blackmisc/simulation/aircraftmodellist.h

@@ -418,6 +418,15 @@ namespace BlackMisc
             //! Airline virtual designators
             QSet<QString> getAirlineVDesignators() const;
 
+            //! Airline ICAO codes for given group, without duplicates
+            Aviation::CAirlineIcaoCodeList getAirlineIcaoCodesForGroup(int groupId) const;
+
+            //! Airline designators
+            QSet<QString> getAirlineDesignatorsForGroup(int groupId) const;
+
+            //! Airline virtual designators
+            QSet<QString> getAirlineVDesignatorsForGroup(int groupId) const;
+
             //! All combined types
             QSet<QString> getCombinedTypes() const;
 

src/blackmisc/stringutils.cpp

@@ -392,6 +392,8 @@ namespace BlackMisc
 
     QString joinStringSet(const QSet<QString> &set, const QString &separator)
     {
+        if (set.isEmpty()) { return {}; }
+        if (set.size() == 1) { return *set.begin(); }
         return set.toList().join(separator);
     }
 
@@ -446,6 +448,12 @@ namespace BlackMisc
         return copy;
     }
 
+    const QString &defaultIfEmpty(const QString &candidate, const QString &defaultIfEmpty)
+    {
+        if (candidate.isEmpty()) { return defaultIfEmpty; }
+        return candidate;
+    }
+
 } // ns
 
 //! \endcond

src/blackmisc/stringutils.h

@@ -292,6 +292,9 @@ namespace BlackMisc
     //! Remove comments such as /** **/ or //
     BLACKMISC_EXPORT QString removeComments(const QString &in, bool removeSlash, bool removeDoubleSlash);
 
+    //! Default string if string is empty
+    BLACKMISC_EXPORT const QString &defaultIfEmpty(const QString &candidate, const QString &defaultIfEmpty);
+
     namespace Mixin
     {
         /*!