class GetLayerVisibility : public QgsScopedExpressionFunction
{
  public:
    GetLayerVisibility( const QgsMapSettings& ms )
        : QgsScopedExpressionFunction( QStringLiteral( "is_layer_visible" ), QgsExpression::ParameterList() << QgsExpression::Parameter( QStringLiteral( "id" ) ), QStringLiteral( "General" ) )
        , mMapSettings( ms )
    {}

    virtual QVariant func( const QVariantList& values, const QgsExpressionContext*, QgsExpression* ) override
    {
      QgsMapLayer* layer = _qgis_findLayer( mMapSettings.layers(), values.at( 0 ).toString() );
      if ( layer )
      {
        return QVariant( true );
      }
      else
      {
        return QVariant( false );
      }
    }

    QgsScopedExpressionFunction* clone() const override
    {
      return new GetLayerVisibility( mMapSettings );
    }

  private:

    const QgsMapSettings& mMapSettings;

};