Closes #28

qt/dbc_tree_model.cpp

@@ -5,6 +5,23 @@
 #include <limits>
 #include <stdexcept>
 
+namespace {
+    QVariantList ToVariantList(const ValueDescriptions &values) {
+        QVariantList descriptions;
+        for (const ValueDescriptions::value_type &entry : values) {
+            QVariantMap pair;
+            if (const std::int64_t *number = std::get_if<std::int64_t>(&entry.first))
+                pair.insert("value", QVariant::fromValue(static_cast<qlonglong>(*number)));
+            else
+                pair.insert("value", QVariant::fromValue(
+                                         static_cast<qulonglong>(std::get<std::uint64_t>(entry.first))));
+            pair.insert("description", QString::fromStdString(entry.second));
+            descriptions.append(pair);
+        }
+        return descriptions;
+    }
+} // namespace
+
 DbcTreeModel::DbcTreeModel(QObject *parent) : QAbstractItemModel(parent) {}
 
 void DbcTreeModel::SetTree(std::unique_ptr<TreeNode> root) {
@@ -60,38 +77,40 @@ QVariant DbcTreeModel::data(const QModelIndex &item, int role) const {
         return {};
     const FrameInfo *frame = node->GetFrame();
     const SignalInfo *signal = node->GetSignal();
-    const QString comment = QString::fromStdString(frame ? frame->comment : signal ? signal->comment
-                                                                                   : "");
+    QString comment;
+    if (frame != nullptr)
+        comment = QString::fromStdString(frame->comment);
+    else if (signal != nullptr)
+        comment = QString::fromStdString(signal->comment);
     if (role == Qt::ToolTipRole || role == CommentRole)
         return comment;
     if (role == NodeTypeRole)
         return static_cast<int>(node->GetType());
     if (role == ValueDescriptionsRole && signal) {
-        QVariantList descriptions;
-        for (const auto &entry: signal->valueDescriptions) {
-            QVariantMap pair;
-            if (const auto *number = std::get_if<std::int64_t>(&entry.first))
-                pair.insert("value", QVariant::fromValue(static_cast<qlonglong>(*number)));
-            else
-                pair.insert("value", QVariant::fromValue(static_cast<qulonglong>(std::get<std::uint64_t>(entry.first))));
-            pair.insert("description", QString::fromStdString(entry.second));
-            descriptions.append(pair);
-        }
-        return descriptions;
+        return ToVariantList(signal->valueDescriptions);
     }
     if (frame) {
-        if (role == CanIdRole) return frame->canId;
-        if (role == PayloadLengthRole) return static_cast<int>(frame->dlc);
-        if (role == ExtendedRole) return frame->isExtended;
+        if (role == CanIdRole)
+            return frame->canId;
+        if (role == PayloadLengthRole)
+            return static_cast<int>(frame->dlc);
+        if (role == ExtendedRole)
+            return frame->isExtended;
     }
     if (signal) {
-        if (role == StartBitRole) return signal->startBit;
-        if (role == BitLengthRole) return signal->length;
-        if (role == LittleEndianRole) return signal->isLittleEndian;
-        if (role == SignedRole) return signal->isSigned;
-        if (role == UnitRole) return QString::fromStdString(signal->unit);
+        if (role == StartBitRole)
+            return signal->startBit;
+        if (role == BitLengthRole)
+            return signal->length;
+        if (role == LittleEndianRole)
+            return signal->isLittleEndian;
+        if (role == SignedRole)
+            return signal->isSigned;
+        if (role == UnitRole)
+            return QString::fromStdString(signal->unit);
     }
-    if (role != Qt::DisplayRole) return {};
+    if (role != Qt::DisplayRole)
+        return {};
     switch (item.column()) {
         case Name:
             return QString::fromStdString(node->GetName());