[apps/calculation] Add a "ctrl-z" system

apps/calculation/calculation_store.cpp

@@ -16,14 +16,24 @@ CalculationStore::CalculationStore(char * buffer, int size) :
   m_buffer(buffer),
   m_bufferSize(size),
   m_calculationAreaEnd(m_buffer),
-  m_numberOfCalculations(0)
+  m_numberOfCalculations(0),
+  m_trashIndex(-1)
 {
   assert(m_buffer != nullptr);
   assert(m_bufferSize > 0);
 }
 
-// Returns an expiring pointer to the calculation of index i
+// Returns an expiring pointer to the calculation of index i, and ignore the trash
 ExpiringPointer<Calculation> CalculationStore::calculationAtIndex(int i) {
+  if (m_trashIndex == -1 || i < m_trashIndex) {
+    return realCalculationAtIndex(i);
+  } else {
+    return realCalculationAtIndex(i + 1);
+  }
+}
+
+// Returns an expiring pointer to the real calculation of index i
+ExpiringPointer<Calculation> CalculationStore::realCalculationAtIndex(int i) {
   assert(i >= 0 && i < m_numberOfCalculations);
   // m_buffer is the address of the oldest calculation in calculation store
   Calculation * c = (Calculation *) m_buffer;
@@ -36,12 +46,13 @@ ExpiringPointer<Calculation> CalculationStore::calculationAtIndex(int i) {
 
 // Pushes an expression in the store
 ExpiringPointer<Calculation> CalculationStore::push(const char * text, Context * context, HeightComputer heightComputer) {
+  emptyTrash();
   /* Compute ans now, before the buffer is updated and before the calculation
    * might be deleted */
   Expression ans = ansExpression(context);
 
   /* Prepare the buffer for the new calculation
-   *The minimal size to store the new calculation is the minimal size of a calculation plus the pointer to its end */
+   * The minimal size to store the new calculation is the minimal size of a calculation plus the pointer to its end */
   int minSize = Calculation::MinimalSize() + sizeof(Calculation *);
   assert(m_bufferSize > minSize);
   while (remainingBufferSize() < minSize) {
@@ -132,15 +143,23 @@ ExpiringPointer<Calculation> CalculationStore::push(const char * text, Context *
 
 // Delete the calculation of index i
 void CalculationStore::deleteCalculationAtIndex(int i) {
+  if (m_trashIndex != -1) {
+    emptyTrash();
+  }
+  m_trashIndex = i;
+}
+
+// Delete the calculation of index i, internal algorithm
+void CalculationStore::realDeleteCalculationAtIndex(int i) {
   assert(i >= 0 && i < m_numberOfCalculations);
   if (i == 0) {
-    ExpiringPointer<Calculation> lastCalculationPointer = calculationAtIndex(0);
+    ExpiringPointer<Calculation> lastCalculationPointer = realCalculationAtIndex(0);
     m_calculationAreaEnd = (char *)(lastCalculationPointer.pointer());
     m_numberOfCalculations--;
     return;
   }
-  char * calcI = (char *)calculationAtIndex(i).pointer();
-  char * nextCalc = (char *) calculationAtIndex(i-1).pointer();
+  char * calcI = (char *)realCalculationAtIndex(i).pointer();
+  char * nextCalc = (char *) realCalculationAtIndex(i-1).pointer();
   assert(m_calculationAreaEnd >= nextCalc);
   size_t slidingSize = m_calculationAreaEnd - nextCalc;
   // Slide the i-1 most recent calculations right after the i+1'th
@@ -200,6 +219,12 @@ bool CalculationStore::pushSerializeExpression(Expression e, char * location, ch
   return expressionIsPushed;
 }
 
+void CalculationStore::emptyTrash() {
+  if (m_trashIndex != -1) {
+    realDeleteCalculationAtIndex(m_trashIndex);
+    m_trashIndex = -1;
+  }
+}
 
 
 Shared::ExpiringPointer<Calculation> CalculationStore::emptyStoreAndPushUndef(Context * context, HeightComputer heightComputer) {
@@ -211,9 +236,9 @@ Shared::ExpiringPointer<Calculation> CalculationStore::emptyStoreAndPushUndef(Co
 
 // Recompute memoized pointers to the calculations after index i
 void CalculationStore::recomputeMemoizedPointersAfterCalculationIndex(int index) {
-  assert(index < m_numberOfCalculations);
+  assert(index < numberOfCalculations());
   // Clear pointer and recompute new ones
-  Calculation * c = calculationAtIndex(index).pointer();
+  Calculation * c = realCalculationAtIndex(index).pointer();
   Calculation * nextCalc;
   while (index != 0) {
     nextCalc = c->next();

apps/calculation/calculation_store.h

@@ -41,11 +41,15 @@ public:
   void deleteCalculationAtIndex(int i);
   void deleteAll();
   int remainingBufferSize() const { assert(m_calculationAreaEnd >= m_buffer); return m_bufferSize - (m_calculationAreaEnd - m_buffer) - m_numberOfCalculations*sizeof(Calculation*); }
-  int numberOfCalculations() const { return m_numberOfCalculations; }
+  int numberOfCalculations() const { return m_numberOfCalculations - (m_trashIndex != -1); }
   Poincare::Expression ansExpression(Poincare::Context * context);
   int bufferSize() { return m_bufferSize; }
+  void reinsertTrash() { m_trashIndex = -1; }
 
 private:
+  void emptyTrash();
+  Shared::ExpiringPointer<Calculation> realCalculationAtIndex(int i);
+  void realDeleteCalculationAtIndex(int i);
 
   class CalculationIterator {
   public:
@@ -70,6 +74,7 @@ private:
   int m_bufferSize;
   const char * m_calculationAreaEnd;
   int m_numberOfCalculations;
+  int m_trashIndex;
 
   size_t deleteOldestCalculation();
   char * addressOfPointerToCalculationOfIndex(int i) {return m_buffer + m_bufferSize - (m_numberOfCalculations - i)*sizeof(Calculation *);}

apps/calculation/edit_expression_controller.cpp

@@ -68,6 +68,15 @@ void EditExpressionController::memoizeInput() {
   *m_cacheBufferInformation = m_contentView.expressionField()->moveCursorAndDumpContent(m_cacheBuffer, k_cacheBufferSize);
 }
 
+bool EditExpressionController::handleEvent(Ion::Events::Event event) {
+  if (event == Ion::Events::ShiftBack) {
+    m_historyController->reinsertTrash();
+    m_historyController->reload();
+    return true;
+  }
+  return false;
+}
+
 void EditExpressionController::viewWillAppear() {
   m_historyController->viewWillAppear();
 }

apps/calculation/edit_expression_controller.h

@@ -31,6 +31,7 @@ public:
   void insertTextBody(const char * text);
   void restoreInput();
   void memoizeInput();
+  bool handleEvent(Ion::Events::Event event) override;
 
   /* TextFieldDelegate */
   bool textFieldDidReceiveEvent(::TextField * textField, Ion::Events::Event event) override;

apps/calculation/history_controller.h

@@ -35,6 +35,7 @@ public:
   int typeAtLocation(int i, int j) override;
   void setSelectedSubviewType(SubviewType subviewType, bool sameCell, int previousSelectedX = -1, int previousSelectedY = -1) override;
   void tableViewDidChangeSelectionAndDidScroll(SelectableTableView * t, int previousSelectedCellX, int previousSelectedCellY, bool withinTemporarySelection = false) override;
+  void reinsertTrash() { m_calculationStore->reinsertTrash(); }
 private:
   int storeIndex(int i) { return numberOfRows() - i - 1; }
   Shared::ExpiringPointer<Calculation> calculationAtIndex(int i);

ion/include/ion/events.h

@@ -142,6 +142,7 @@ constexpr Event ShiftRight = Event::ShiftKey(Keyboard::Key::Right);
 constexpr Event ShiftUp    = Event::ShiftKey(Keyboard::Key::Up);
 constexpr Event ShiftDown  = Event::ShiftKey(Keyboard::Key::Down);
 constexpr Event ShiftOK    = Event::ShiftKey(Keyboard::Key::OK);
+constexpr Event ShiftBack  = Event::ShiftKey(Keyboard::Key::Back);
 
 constexpr Event AlphaLock = Event::ShiftKey(Keyboard::Key::Alpha);
 constexpr Event Cut = Event::ShiftKey(Keyboard::Key::XNT);

ion/src/shared/keyboard/layout_B2/layout_events.cpp

@@ -16,7 +16,7 @@ const EventData s_dataForEvent[4 * Event::PageSize] = {
   T("1"), T("2"), T("3"), T("+"), T("-"), U(),
   T("0"), T("."), T("ᴇ"), TL(), TL(), U(),
 // Shift
-  TL(), TL(), TL(), TL(), TL(), U(),
+  TL(), TL(), TL(), TL(), TL(), TL(),
   TL(), U(), U(), U(), U(), U(),
   U(), U(), TL(), TL(), TL(), TL(),
   T("["), T("]"), T("{"), T("}"), T("_"), T("→"),
@@ -61,7 +61,7 @@ const char * const s_nameForEvent[255] = {
   "One", "Two", "Three", "Plus", "Minus", nullptr,
   "Zero", "Dot", "EE", "Ans", "EXE", nullptr,
   //Shift,
-  "ShiftLeft", "ShiftUp", "ShiftDown", "ShiftRight", "ShiftOK", nullptr,
+  "ShiftLeft", "ShiftUp", "ShiftDown", "ShiftRight", "ShiftOK", "ShiftBack",
   "ShiftHome", nullptr, nullptr, nullptr, nullptr, nullptr,
   nullptr, "AlphaLock", "Cut", "Copy", "Paste", "Clear",
   "LeftBracket", "RightBracket", "LeftBrace", "RightBrace", "Underscore", "Sto",

ion/src/shared/keyboard/layout_B3/layout_events.cpp

@@ -16,7 +16,7 @@ const EventData s_dataForEvent[4 * Event::PageSize] = {
   T("1"), T("2"), T("3"), T("+"), T("-"), U(),
   T("0"), T("."), T("ᴇ"), TL(), TL(), U(),
 // Shift
-  TL(), TL(), TL(), TL(), TL(), U(),
+  TL(), TL(), TL(), TL(), TL(), TL(),
   TL(), U(), U(), U(), U(), U(),
   U(), U(), TL(), TL(), TL(), TL(),
   T("["), T("]"), T("{"), T("}"), T("_"), T("→"),
@@ -61,7 +61,7 @@ const char * const s_nameForEvent[255] = {
   "One", "Two", "Three", "Plus", "Minus", nullptr,
   "Zero", "Dot", "EE", "Ans", "EXE", nullptr,
   //Shift,
-  "ShiftLeft", "ShiftUp", "ShiftDown", "ShiftRight", "ShiftOK", nullptr,
+  "ShiftLeft", "ShiftUp", "ShiftDown", "ShiftRight", "ShiftOK", "ShiftBack",
   "ShiftHome", nullptr, nullptr, nullptr, nullptr, nullptr,
   nullptr, "AlphaLock", "Cut", "Copy", "Paste", "Clear",
   "LeftBracket", "RightBracket", "LeftBrace", "RightBrace", "Underscore", "Sto",