Make sure a lot of foreach loops use references

src/app/composer/qgscomposerlegendwidget.cpp

@@ -795,7 +795,7 @@ void QgsComposerLegendWidget::resetLayerNodeToDefaults()
 
   mLegend->beginCommand( tr( "Legend updated" ) );
 
-  foreach ( QString key, nodeLayer->customProperties() )
+  foreach ( const QString& key, nodeLayer->customProperties() )
   {
     if ( key.startsWith( "legend/" ) )
       nodeLayer->removeCustomProperty( key );

src/app/composer/qgscomposermapwidget.cpp

@@ -298,7 +298,7 @@ void QgsComposerMapWidget::aboutToShowVisibilityPresetsMenu()
     return;
 
   menu->clear();
-  foreach ( QString presetName, QgsProject::instance()->visibilityPresetCollection()->presets() )
+  foreach ( const QString& presetName, QgsProject::instance()->visibilityPresetCollection()->presets() )
   {
     QAction* a = menu->addAction( presetName, this, SLOT( visibilityPresetSelected() ) );
     a->setCheckable( true );

src/app/main.cpp

@@ -1141,7 +1141,7 @@ APP_EXPORT int main( int argc, char *argv[] )
     QList< QPair<QgsVectorLayer *, int > > layers;
     if ( !dxfPreset.isEmpty() )
     {
-      foreach ( QString layer, QgsProject::instance()->visibilityPresetCollection()->presetVisibleLayers( dxfPreset ) )
+      foreach ( const QString& layer, QgsProject::instance()->visibilityPresetCollection()->presetVisibleLayers( dxfPreset ) )
       {
         QgsVectorLayer *vl = qobject_cast<QgsVectorLayer *>( QgsMapLayerRegistry::instance()->mapLayer( layer ) );
         if ( !vl )

src/app/qgisapp.cpp

@@ -2870,7 +2870,7 @@ void QgisApp::updateProjectFromTemplates()
   mProjectFromTemplateMenu->clear();
 
   // Add entries
-  foreach ( QString templateFile, templateFiles )
+  foreach ( const QString& templateFile, templateFiles )
   {
     mProjectFromTemplateMenu->addAction( templateFile );
   }
@@ -3003,7 +3003,7 @@ QString QgisApp::crsAndFormatAdjustedLayerUri( const QString &uri, const QString
 
   // Adjust layer CRS to project CRS
   QgsCoordinateReferenceSystem testCrs;
-  foreach ( QString c, supportedCrs )
+  foreach ( const QString& c, supportedCrs )
   {
     testCrs.createFromOgcWmsCrs( c );
     if ( testCrs == mMapCanvas->mapSettings().destinationCrs() )
@@ -3016,7 +3016,7 @@ QString QgisApp::crsAndFormatAdjustedLayerUri( const QString &uri, const QString
 
   // Use the last used image format
   QString lastImageEncoding = QSettings().value( "/qgis/lastWmsImageEncoding", "image/png" ).toString();
-  foreach ( QString fmt, supportedFormats )
+  foreach ( const QString& fmt, supportedFormats )
   {
     if ( fmt == lastImageEncoding )
     {
@@ -3561,7 +3561,7 @@ void QgisApp::addDatabaseLayers( QStringList const & layerPathList, QString cons
 
   QApplication::setOverrideCursor( Qt::WaitCursor );
 
-  foreach ( QString layerPath, layerPathList )
+  foreach ( const QString& layerPath, layerPathList )
   {
     // create the layer
     QgsDataSourceURI uri( layerPath );

src/app/qgsbookmarks.cpp

@@ -293,7 +293,7 @@ void QgsBookmarks::importFromXML()
   QStringList queriesList = queries.split( ";" );
   QSqlQuery query( model->database() );
 
-  foreach ( QString queryTxt, queriesList )
+  foreach ( const QString& queryTxt, queriesList )
   {
     if ( queryTxt.trimmed().isEmpty() )
     {

src/app/qgsbrowserdockwidget.cpp

@@ -135,7 +135,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
       mREList.clear();
       if ( mPatternSyntax == "normal" )
       {
-        foreach ( QString f, mFilter.split( "|" ) )
+        foreach ( const QString& f, mFilter.split( "|" ) )
         {
           QRegExp rx( QString( "*%1*" ).arg( f.trimmed() ) );
           rx.setPatternSyntax( QRegExp::Wildcard );
@@ -145,7 +145,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
       }
       else if ( mPatternSyntax == "wildcard" )
       {
-        foreach ( QString f, mFilter.split( "|" ) )
+        foreach ( const QString& f, mFilter.split( "|" ) )
         {
           QRegExp rx( f.trimmed() );
           rx.setPatternSyntax( QRegExp::Wildcard );
@@ -175,7 +175,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
     {
       if ( mPatternSyntax == "normal" || mPatternSyntax == "wildcard" )
       {
-        foreach ( QRegExp rx, mREList )
+        foreach ( const QRegExp& rx, mREList )
         {
           QgsDebugMsg( QString( "value: [%1] rx: [%2] match: %3" ).arg( value ).arg( rx.pattern() ).arg( rx.exactMatch( value ) ) );
           if ( rx.exactMatch( value ) )
@@ -184,7 +184,7 @@ class QgsBrowserTreeFilterProxyModel : public QSortFilterProxyModel
       }
       else
       {
-        foreach ( QRegExp rx, mREList )
+        foreach ( const QRegExp& rx, mREList )
         {
           QgsDebugMsg( QString( "value: [%1] rx: [%2] match: %3" ).arg( value ).arg( rx.pattern() ).arg( rx.indexIn( value ) ) );
           if ( rx.indexIn( value ) != -1 )

src/app/qgsclipboard.cpp

@@ -162,7 +162,7 @@ QgsFeatureList QgsClipboard::copyOf( const QgsFields &fields )
     return mFeatureClipboard;
 
   QgsFeatureList features;
-  foreach ( QString row, values )
+  foreach ( const QString& row, values )
   {
     // Assume that it's just WKT for now.
     QgsGeometry* geometry = QgsGeometry::fromWkt( row );

src/app/qgsmaptoolfeatureaction.cpp

@@ -131,7 +131,7 @@ bool QgsMapToolFeatureAction::doAction( QgsVectorLayer *layer, int x, int y )
   if ( featList.size() == 0 )
     return false;
 
-  foreach ( QgsFeature feat, featList )
+  foreach ( const QgsFeature& feat, featList )
   {
     if ( layer->actions()->defaultAction() >= 0 )
     {

src/app/qgsoptions.cpp

@@ -750,7 +750,7 @@ QgsOptions::QgsOptions( QWidget *parent, Qt::WindowFlags fl ) :
   lblSystemLocale->setText( tr( "Detected active locale on your system: %1" ).arg( mySystemLocale ) );
   QString myUserLocale = settings.value( "locale/userLocale", "" ).toString();
   QStringList myI18nList = i18nList();
-  foreach ( QString l, myI18nList )
+  foreach ( const QString& l, myI18nList )
   {
     cboLocale->addItem( QIcon( QString( ":/images/flags/%1.png" ).arg( l ) ), QLocale( l ).nativeLanguageName(), l );
   }
@@ -1762,11 +1762,11 @@ void QgsOptions::loadGdalDriverList()
   // myDrivers.sort();
   // sort list case insensitive - no existing function for this!
   QMap<QString, QString> strMap;
-  foreach ( QString str, myDrivers )
+  foreach ( const QString& str, myDrivers )
     strMap.insert( str.toLower(), str );
   myDrivers = strMap.values();
 
-  foreach ( QString myName, myDrivers )
+  foreach ( const QString& myName, myDrivers )
   {
     QTreeWidgetItem * mypItem = new QTreeWidgetItem( QStringList( myName ) );
     if ( mySkippedDrivers.contains( myName ) )
@@ -1794,13 +1794,13 @@ void QgsOptions::loadGdalDriverList()
 
   // populate cmbEditCreateOptions with gdal write drivers - sorted, GTiff first
   strMap.clear();
-  foreach ( QString str, myGdalWriteDrivers )
+  foreach ( const QString& str, myGdalWriteDrivers )
     strMap.insert( str.toLower(), str );
   myGdalWriteDrivers = strMap.values();
   myGdalWriteDrivers.removeAll( "Gtiff" );
   myGdalWriteDrivers.prepend( "GTiff" );
   cmbEditCreateOptions->clear();
-  foreach ( QString myName, myGdalWriteDrivers )
+  foreach ( const QString& myName, myGdalWriteDrivers )
   {
     cmbEditCreateOptions->addItem( myName );
   }

src/app/qgspluginregistry.cpp

@@ -138,8 +138,9 @@ void QgsPluginRegistry::dump()
   if ( mPythonUtils && mPythonUtils->isEnabled() )
   {
     QgsDebugMsg( "PYTHON PLUGINS IN REGISTRY:" );
-    foreach ( QString pluginName, mPythonUtils->listActivePlugins() )
+    foreach ( const QString& pluginName, mPythonUtils->listActivePlugins() )
     {
+      Q_UNUSED( pluginName );
       QgsDebugMsg( pluginName );
     }
   }
@@ -176,7 +177,7 @@ void QgsPluginRegistry::unloadAll()
 
   if ( mPythonUtils && mPythonUtils->isEnabled() )
   {
-    foreach ( QString pluginName, mPythonUtils->listActivePlugins() )
+    foreach ( const QString& pluginName, mPythonUtils->listActivePlugins() )
     {
       mPythonUtils->unloadPlugin( pluginName );
     }

src/app/qgsprojectlayergroupdialog.cpp

@@ -62,7 +62,7 @@ QStringList QgsProjectLayerGroupDialog::selectedGroups() const
 {
   QStringList groups;
   QgsLayerTreeModel* model = mTreeView->layerTreeModel();
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     QgsLayerTreeNode* node = model->index2node( index );
     if ( QgsLayerTree::isGroup( node ) )
@@ -75,7 +75,7 @@ QStringList QgsProjectLayerGroupDialog::selectedLayerIds() const
 {
   QStringList layerIds;
   QgsLayerTreeModel* model = mTreeView->layerTreeModel();
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     QgsLayerTreeNode* node = model->index2node( index );
     if ( QgsLayerTree::isLayer( node ) )
@@ -88,7 +88,7 @@ QStringList QgsProjectLayerGroupDialog::selectedLayerNames() const
 {
   QStringList layerNames;
   QgsLayerTreeModel* model = mTreeView->layerTreeModel();
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     QgsLayerTreeNode* node = model->index2node( index );
     if ( QgsLayerTree::isLayer( node ) )
@@ -204,7 +204,7 @@ void QgsProjectLayerGroupDialog::removeEmbeddedNodes( QgsLayerTreeGroup* node )
 
 void QgsProjectLayerGroupDialog::onTreeViewSelectionChanged()
 {
-  foreach ( QModelIndex index, mTreeView->selectionModel()->selectedIndexes() )
+  foreach ( const QModelIndex& index, mTreeView->selectionModel()->selectedIndexes() )
   {
     unselectChildren( index );
   }

src/app/qgsprojectproperties.cpp

@@ -311,7 +311,7 @@ QgsProjectProperties::QgsProjectProperties( QgsMapCanvas* mapCanvas, QWidget *pa
     if ( grpWMSList->isChecked() )
     {
       QStringList list;
-      foreach ( QString value, values )
+      foreach ( const QString& value, values )
       {
         list << QString( "EPSG:%1" ).arg( value );
       }

src/app/qgsrasterlayerproperties.cpp

@@ -355,7 +355,7 @@ QgsRasterLayerProperties::QgsRasterLayerProperties( QgsMapLayer* lyr, QgsMapCanv
 
   //fill available renderers into combo box
   QgsRasterRendererRegistryEntry entry;
-  foreach ( QString name, QgsRasterRendererRegistry::instance()->renderersList() )
+  foreach ( const QString& name, QgsRasterRendererRegistry::instance()->renderersList() )
   {
     if ( QgsRasterRendererRegistry::instance()->rendererData( name, entry ) )
     {

src/app/qgssnappingdialog.cpp

@@ -459,7 +459,7 @@ void QgsSnappingDialog::addLayer( QgsMapLayer *theMapLayer )
 
 void QgsSnappingDialog::layersWillBeRemoved( QStringList thelayers )
 {
-  foreach ( QString theLayerId, thelayers )
+  foreach ( const QString& theLayerId, thelayers )
   {
     QTreeWidgetItem *item = 0;
 

src/app/qgsvisibilitypresets.cpp

@@ -59,7 +59,7 @@ void QgsVisibilityPresets::addPerLayerCheckedLegendSymbols( QgsVisibilityPresetC
 {
   QgsLayerTreeModel* model = QgisApp::instance()->layerTreeView()->layerTreeModel();
 
-  foreach ( QString layerID, rec.mVisibleLayerIDs )
+  foreach ( const QString& layerID, rec.mVisibleLayerIDs )
   {
     QgsLayerTreeLayer* nodeLayer = model->rootGroup()->findLayer( layerID );
     if ( !nodeLayer )
@@ -90,7 +90,7 @@ void QgsVisibilityPresets::addPerLayerCurrentStyle( QgsVisibilityPresetCollectio
 {
   QgsLayerTreeModel* model = QgisApp::instance()->layerTreeView()->layerTreeModel();
 
-  foreach ( QString layerID, rec.mVisibleLayerIDs )
+  foreach ( const QString& layerID, rec.mVisibleLayerIDs )
   {
     QgsLayerTreeLayer* nodeLayer = model->rootGroup()->findLayer( layerID );
     if ( !nodeLayer )
@@ -136,7 +136,7 @@ QStringList QgsVisibilityPresets::orderedPresetVisibleLayers( const QString& nam
   QgsLayerTreeMapCanvasBridge* bridge = QgisApp::instance()->layerTreeCanvasBridge();
   QStringList order = bridge->hasCustomLayerOrder() ? bridge->customLayerOrder() : bridge->defaultLayerOrder();
   QStringList order2;
-  foreach ( QString layerID, order )
+  foreach ( const QString& layerID, order )
   {
     if ( visibleIds.contains( layerID ) )
       order2 << layerID;

src/core/composer/qgsatlascomposition.cpp

@@ -70,7 +70,7 @@ void QgsAtlasComposition::removeLayers( QStringList layers )
     return;
   }
 
-  foreach ( QString layerId, layers )
+  foreach ( const QString& layerId, layers )
   {
     if ( layerId == mCoverageLayer->id() )
     {

src/core/composer/qgscomposermap.cpp

@@ -555,7 +555,7 @@ QStringList QgsComposerMap::layersToRender() const
 
     QStringList layerNames = exprVal.toString().split( "|" );
     //need to convert layer names to layer ids
-    Q_FOREACH ( QString name, layerNames )
+    Q_FOREACH ( const QString& name, layerNames )
     {
       QList< QgsMapLayer* > matchingLayers = QgsMapLayerRegistry::instance()->mapLayersByName( name );
       Q_FOREACH ( QgsMapLayer* layer, matchingLayers )

src/core/composer/qgscomposertablev2.cpp

@@ -942,7 +942,7 @@ bool QgsComposerTableV2::calculateMaxColumnWidths()
         //column width set to automatic, so check content size
         QStringList multiLineSplit = ( *colIt ).toString().split( "\n" );
         currentCellTextWidth = 0;
-        Q_FOREACH ( QString line, multiLineSplit )
+        Q_FOREACH ( const QString& line, multiLineSplit )
         {
           currentCellTextWidth = qMax( currentCellTextWidth, QgsComposerUtils::textWidthMM( mContentFont, line ) );
         }
@@ -1168,7 +1168,7 @@ bool QgsComposerTableV2::textRequiresWrapping( const QString& text, double colum
 
   QStringList multiLineSplit = text.split( "\n" );
   double currentTextWidth = 0;
-  Q_FOREACH ( QString line, multiLineSplit )
+  Q_FOREACH ( const QString& line, multiLineSplit )
   {
     currentTextWidth = qMax( currentTextWidth, QgsComposerUtils::textWidthMM( font, line ) );
   }
@@ -1180,15 +1180,15 @@ QString QgsComposerTableV2::wrappedText( const QString &value, double columnWidt
 {
   QStringList lines = value.split( "\n" );
   QStringList outLines;
-  Q_FOREACH ( QString line, lines )
+  Q_FOREACH ( const QString& line, lines )
   {
     if ( textRequiresWrapping( line, columnWidth, font ) )
     {
       //first step is to identify words which must be on their own line (too long to fit)
       QStringList words = line.split( " " );
       QStringList linesToProcess;
       QString wordsInCurrentLine;
-      Q_FOREACH ( QString word, words )
+      Q_FOREACH ( const QString& word, words )
       {
         if ( textRequiresWrapping( word, columnWidth, font ) )
         {
@@ -1208,7 +1208,7 @@ QString QgsComposerTableV2::wrappedText( const QString &value, double columnWidt
       if ( !wordsInCurrentLine.isEmpty() )
         linesToProcess << wordsInCurrentLine;
 
-      Q_FOREACH ( QString line, linesToProcess )
+      Q_FOREACH ( const QString& line, linesToProcess )
       {
         QString remainingText = line;
         int lastPos = remainingText.lastIndexOf( " " );

src/core/diagram/qgshistogramdiagram.cpp

@@ -53,7 +53,7 @@ QSizeF QgsHistogramDiagram::diagramSize( const QgsFeature& feature, const QgsRen
   if ( feature.fields() )
     expressionContext.setFields( *feature.fields() );
 
-  foreach ( QString cat, s.categoryAttributes )
+  foreach ( const QString& cat, s.categoryAttributes )
   {
     QgsExpression* expression = getExpression( cat, expressionContext );
     maxValue = qMax( expression->evaluate( &expressionContext ).toDouble(), maxValue );
@@ -135,7 +135,7 @@ void QgsHistogramDiagram::renderDiagram( const QgsFeature& feature, QgsRenderCon
   if ( feature.fields() )
     expressionContext.setFields( *feature.fields() );
 
-  foreach ( QString cat, s.categoryAttributes )
+  foreach ( const QString& cat, s.categoryAttributes )
   {
     QgsExpression* expression = getExpression( cat, expressionContext );
     double currentVal = expression->evaluate( &expressionContext ).toDouble();