[escher] In alternate empty view delegate, make is empty method const

Change-Id: Iad3fbfef4deb76676b0373cfb3c919127efc3207

apps/graph/graph/graph_controller.cpp

@@ -22,7 +22,7 @@ View * GraphController::view() {
   return &m_view;
 }
 
-bool GraphController::isEmpty() {
+bool GraphController::isEmpty() const {
   if (m_functionStore->numberOfActiveFunctions() == 0) {
     return true;
   }

apps/graph/graph/graph_controller.h

@@ -17,7 +17,7 @@ public:
   void didBecomeFirstResponder() override;
   ViewController * initialisationParameterController() override;
 
-  bool isEmpty() override;
+  bool isEmpty() const override;
   const char * emptyMessage() override;
 
   bool didChangeRange(InteractiveCurveViewRange * interactiveCurveViewRange) override;

apps/graph/values/values_controller.cpp

@@ -249,7 +249,7 @@ int ValuesController::typeAtLocation(int i, int j) {
   return 3;
 }
 
-bool ValuesController::isEmpty() {
+bool ValuesController::isEmpty() const {
   if (m_functionStore->numberOfActiveFunctions() == 0) {
     return true;
   }

apps/graph/values/values_controller.h

@@ -31,7 +31,7 @@ public:
   TableViewCell * reusableCell(int index, int type) override;
   int reusableCellCount(int type) override;
   int typeAtLocation(int i, int j) override;
-  bool isEmpty() override;
+  bool isEmpty() const override;
   const char * emptyMessage() override;
   Responder * defaultController() override;
   static constexpr KDCoordinate k_topMargin = 10;

apps/regression/calculation_controller.cpp

@@ -78,7 +78,7 @@ void CalculationController::tableViewDidChangeSelection(SelectableTableView * t,
   }
 }
 
-bool CalculationController::isEmpty() {
+bool CalculationController::isEmpty() const {
   if (m_store->numberOfPairs() == 0) {
     return true;
   }

apps/regression/calculation_controller.h

@@ -17,7 +17,7 @@ public:
   void didBecomeFirstResponder() override;
   void tableViewDidChangeSelection(SelectableTableView * t, int previousSelectedCellX, int previousSelectedCellY) override;
 
-  bool isEmpty() override;
+  bool isEmpty() const override;
   const char * emptyMessage() override;
   Responder * defaultController() override;
 

apps/regression/graph_controller.cpp

@@ -18,7 +18,7 @@ ViewController * GraphController::initialisationParameterController() {
   return &m_initialisationParameterController;
 }
 
-bool GraphController::isEmpty() {
+bool GraphController::isEmpty() const {
   if (m_store->numberOfPairs() < 2 || isinf(m_store->slope()) || isnan(m_store->slope())) {
     return true;
   }

apps/regression/graph_controller.h

@@ -16,7 +16,7 @@ class GraphController : public InteractiveCurveViewController {
 public:
   GraphController(Responder * parentResponder, HeaderViewController * headerViewController, Store * store);
   ViewController * initialisationParameterController() override;
-  bool isEmpty() override;
+  bool isEmpty() const override;
   const char * emptyMessage() override;
 private:
   constexpr static float k_cursorTopMarginRatio = 0.025f;

apps/statistics/box_controller.cpp

@@ -42,7 +42,7 @@ void BoxController::didBecomeFirstResponder() {
   reloadBannerView();
 }
 
-bool BoxController::isEmpty() {
+bool BoxController::isEmpty() const {
   if (m_store->sumOfColumn(1) == 0) {
     return true;
   }

apps/statistics/box_controller.h

@@ -15,7 +15,7 @@ public:
   View * view() override;
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
-  bool isEmpty() override;
+  bool isEmpty() const override;
   const char * emptyMessage() override;
   Responder * defaultController() override;
 private:

apps/statistics/calculation_controller.cpp

@@ -46,7 +46,7 @@ void CalculationController::didBecomeFirstResponder() {
   app()->setFirstResponder(&m_selectableTableView);
 }
 
-bool CalculationController::isEmpty() {
+bool CalculationController::isEmpty() const {
   if (m_store->sumOfColumn(1) == 0) {
     return true;
   }

apps/statistics/calculation_controller.h

@@ -15,7 +15,7 @@ public:
   bool handleEvent(Ion::Events::Event event) override;
   void didBecomeFirstResponder() override;
 
-  bool isEmpty() override;
+  bool isEmpty() const override;
   const char * emptyMessage() override;
   Responder * defaultController() override;
 

apps/statistics/histogram_controller.cpp

@@ -100,7 +100,7 @@ Button * HistogramController::buttonAtIndex(int index) {
   return &m_settingButton;
 }
 
-bool HistogramController::isEmpty() {
+bool HistogramController::isEmpty() const {
   if (m_store->sumOfColumn(1) == 0) {
     return true;
   }

apps/statistics/histogram_controller.h

@@ -24,7 +24,7 @@ public:
   int numberOfButtons() const override;
   Button * buttonAtIndex(int index) override;
 
-  bool isEmpty() override;
+  bool isEmpty() const override;
   const char * emptyMessage() override;
   Responder * defaultController() override;
 private:

escher/include/escher/alternate_empty_view_delegate.h

@@ -7,7 +7,7 @@ class AlternateEmptyViewController;
 
 class AlternateEmptyViewDelegate {
 public:
-  virtual bool isEmpty() = 0;
+  virtual bool isEmpty() const = 0;
   virtual const char * emptyMessage() = 0;
   virtual Responder * defaultController() = 0;
 };