Sort filter results so closer matches appear higher

A closer match means more of the text is matched, ie
a short string inside a long string is penalised

python/gui/locator/qgslocatorfilter.sip

@@ -52,6 +52,11 @@ class QgsLocatorResult
  Icon for result.
 %End
 
+    double score = 0.5;
+%Docstring
+ Match score, from 0 - 1, where 1 represents a perfect match.
+%End
+
 };
 
 class QgsLocatorFilter : QObject

python/plugins/processing/gui/AlgorithmLocatorFilter.py

@@ -64,6 +64,10 @@ def fetchResults(self,string,context,feedback):
                 result.displayString = a.displayName()
                 result.icon = a.icon()
                 result.userData = a.id()
+                if string.lower() in a.displayName().lower():
+                    result.score = float(len(string)) / len(a.displayName())
+                else:
+                    result.score = 0
                 self.resultFetched.emit(result)
 
     def triggerResult(self, result):

src/app/locator/qgsinbuiltlocatorfilters.cpp

@@ -47,6 +47,7 @@ void QgsLayerTreeLocatorFilter::fetchResults( const QString &string, const QgsLo
       result.displayString = layer->layer()->name();
       result.userData = layer->layerId();
       result.icon = QgsMapLayerModel::iconForLayer( layer->layer() );
+      result.score = static_cast< double >( string.length() ) / layer->layer()->name().length();
       emit resultFetched( result );
     }
   }
@@ -81,6 +82,7 @@ void QgsLayoutLocatorFilter::fetchResults( const QString &string, const QgsLocat
       result.displayString = composition->name();
       result.userData = composition->name();
       //result.icon = QgsMapLayerModel::iconForLayer( layer->layer() );
+      result.score = static_cast< double >( string.length() ) / composition->name().length();
       emit resultFetched( result );
     }
   }
@@ -155,6 +157,7 @@ void QgsActionLocatorFilter::searchActions( const QString &string, QWidget *pare
       result.displayString = searchText;
       result.userData = QVariant::fromValue( action );
       result.icon = action->icon();
+      result.score = static_cast< double >( string.length() ) / searchText.length();
       emit resultFetched( result );
       found << action;
     }

src/gui/locator/qgslocatorfilter.h

@@ -72,6 +72,11 @@ class GUI_EXPORT QgsLocatorResult
      */
     QIcon icon;
 
+    /**
+     * Match score, from 0 - 1, where 1 represents a perfect match.
+     */
+    double score = 0.5;
+
 };
 
 /**

src/gui/locator/qgslocatorwidget.cpp

@@ -317,6 +317,12 @@ QVariant QgsLocatorModel::data( const QModelIndex &index, int role ) const
       else
         return 1;
 
+    case ResultScoreRole:
+      if ( mResults.at( index.row() ).filter )
+        return 0;
+      else
+        return ( mResults.at( index.row() ).result.score );
+
     case ResultFilterPriorityRole:
       if ( !mResults.at( index.row() ).filter )
         return mResults.at( index.row() ).result.filter->priority();
@@ -443,6 +449,12 @@ bool QgsLocatorProxyModel::lessThan( const QModelIndex &left, const QModelIndex
   if ( leftTypeRole != rightTypeRole )
     return leftTypeRole < rightTypeRole;
 
+  // sort filter's results by score
+  double leftScore = sourceModel()->data( left, QgsLocatorModel::ResultScoreRole ).toDouble();
+  double rightScore = sourceModel()->data( right, QgsLocatorModel::ResultScoreRole ).toDouble();
+  if ( !qgsDoubleNear( leftScore, rightScore ) )
+    return leftScore > rightScore;
+
   // lastly sort filter's results by string
   leftFilter = sourceModel()->data( left, Qt::DisplayRole ).toString();
   rightFilter = sourceModel()->data( right, Qt::DisplayRole ).toString();

src/gui/locator/qgslocatorwidget.h

@@ -128,6 +128,7 @@ class QgsLocatorModel : public QAbstractListModel
       ResultDataRole = Qt::UserRole + 1, //!< QgsLocatorResult data
       ResultTypeRole,
       ResultFilterPriorityRole,
+      ResultScoreRole,
       ResultFilterNameRole,
     };