[BalooRolesProvider] Use Property IDs instead of string matching

Instantiating KFileMetaDataInfo for each file and property, even when
the role is not used, is somewhat expensive and unnecessary. Use the
numeric Property ID to map it to a role, and only instantiate the used
PropertyInfo's.

Remove the properties provided by KFM::UserMetaData from the map, as
these will newer match.

src/kitemviews/private/kbaloorolesprovider.cpp

@@ -28,6 +28,32 @@ namespace {
         std::sort(alphabeticalOrderTags.begin(), alphabeticalOrderTags.end(), [&](const QString& s1, const QString& s2){ return coll.compare(s1, s2) < 0; });
         return alphabeticalOrderTags.join(QLatin1String(", "));
     }
+
+    using Property = KFileMetaData::Property::Property;
+    // Mapping from the KFM::Property to the KFileItemModel roles.
+    const QHash<Property, QByteArray> propertyRoleMap() {
+        static const auto map = QHash<Property, QByteArray> {
+            { Property::Rating,            QByteArrayLiteral("rating") },
+            { Property::Comment,           QByteArrayLiteral("comment") },
+            { Property::Title,             QByteArrayLiteral("title") },
+            { Property::WordCount,         QByteArrayLiteral("wordCount") },
+            { Property::LineCount,         QByteArrayLiteral("lineCount") },
+            { Property::Width,             QByteArrayLiteral("width") },
+            { Property::Height,            QByteArrayLiteral("height") },
+            { Property::ImageDateTime,     QByteArrayLiteral("imageDateTime") },
+            { Property::ImageOrientation,  QByteArrayLiteral("orientation") },
+            { Property::Artist,            QByteArrayLiteral("artist") },
+            { Property::Genre,             QByteArrayLiteral("genre")  },
+            { Property::Album,             QByteArrayLiteral("album") },
+            { Property::Duration,          QByteArrayLiteral("duration") },
+            { Property::BitRate,           QByteArrayLiteral("bitrate") },
+            { Property::AspectRatio,       QByteArrayLiteral("aspectRatio") },
+            { Property::FrameRate,         QByteArrayLiteral("frameRate") },
+            { Property::ReleaseYear,       QByteArrayLiteral("releaseYear") },
+            { Property::TrackNumber,       QByteArrayLiteral("track") }
+        };
+        return map;
+    }
 }
 
 struct KBalooRolesProviderSingleton
@@ -63,17 +89,17 @@ QHash<QByteArray, QVariant> KBalooRolesProvider::roleValues(const Baloo::File& f
 
     while (rangeBegin != propMap.constKeyValueEnd()) {
         auto key = (*rangeBegin).first;
-        const KFileMetaData::PropertyInfo propertyInfo(key);
-        const QByteArray role = roleForProperty(propertyInfo.name());
 
         auto rangeEnd = std::find_if(rangeBegin, propMap.constKeyValueEnd(),
             [key](const entry& e) { return e.first != key; });
 
+        const QByteArray role = propertyRoleMap().value(key);
         if (role.isEmpty() || !roles.contains(role)) {
             rangeBegin = rangeEnd;
             continue;
         }
 
+        const KFileMetaData::PropertyInfo propertyInfo(key);
         auto distance = std::distance(rangeBegin, rangeEnd);
         if (distance > 1) {
             QVariantList list;
@@ -130,41 +156,15 @@ QHash<QByteArray, QVariant> KBalooRolesProvider::roleValues(const Baloo::File& f
 
 KBalooRolesProvider::KBalooRolesProvider()
 {
-    struct PropertyInfo
-    {
-        const char* const property;
-        const char* const role;
-    };
-
-    // Mapping from the URIs to the KFileItemModel roles. Note that this must not be
-    // a 1:1 mapping: One role may contain several URI-values
-    static const PropertyInfo propertyInfoList[] = {
-        { "rating", "rating" },
-        { "tag",        "tags" },
-        { "comment",   "comment" },
-        { "title",         "title" },
-        { "wordCount",     "wordCount" },
-        { "lineCount",     "lineCount" },
-        { "width",         "width" },
-        { "height",        "height" },
-        { "imageDateTime",   "imageDateTime"},
-        { "imageOrientation", "orientation", },
-        { "artist",     "artist" },
-        { "genre",	"genre"  },
-        { "album",    "album" },
-        { "duration",      "duration" },
-        { "bitRate", "bitrate" },
-        { "aspectRatio", "aspectRatio" },
-        { "frameRate", "frameRate" },
-        { "releaseYear",    "releaseYear" },
-        { "trackNumber",   "track" },
-        { "originUrl", "originUrl" }
-    };
-
-    for (unsigned int i = 0; i < sizeof(propertyInfoList) / sizeof(PropertyInfo); ++i) {
-        m_roleForProperty.insert(propertyInfoList[i].property, propertyInfoList[i].role);
-        m_roles.insert(propertyInfoList[i].role);
+    // Display roles filled from Baloo property cache
+    for (const auto& role : propertyRoleMap()) {
+        m_roles.insert(role);
     }
 
+    // Display roles provided by UserMetaData
+    m_roles.insert(QByteArrayLiteral("tags"));
+    m_roles.insert(QByteArrayLiteral("rating"));
+    m_roles.insert(QByteArrayLiteral("comment"));
+    m_roles.insert(QByteArrayLiteral("originUrl"));
 }
 

src/kitemviews/private/kbaloorolesprovider.h

@@ -47,7 +47,6 @@ protected:
 
 private:
     QSet<QByteArray> m_roles;
-    QHash<QString, QByteArray> m_roleForProperty;
 
     friend struct KBalooRolesProviderSingleton;
 };