[poincare] Redesign the text method of expression to avoid keeping a

buffer in all expressions

Change-Id: I2ca33be09a525adf429854e651beaa75e5605d7a

apps/calculation/calculation.h

@@ -17,9 +17,9 @@ public:
   ExpressionLayout * evaluationLayout();
   void setContent(const char * c, Context * context);
   bool isEmpty();
+  constexpr static int k_maximalExpressionTextLength = 255;
 private:
-  constexpr static int k_bodyLength = 255;
-  char m_text[k_bodyLength];
+  char m_text[k_maximalExpressionTextLength];
   Expression * m_expression;
   ExpressionLayout * m_layout;
   Expression * m_evaluation;

apps/calculation/history_controller.cpp

@@ -1,6 +1,5 @@
 #include "history_controller.h"
 #include "app.h"
-#include "../constant.h"
 #include <assert.h>
 
 namespace Calculation {
@@ -47,7 +46,8 @@ bool HistoryController::handleEvent(Ion::Events::Event event) {
     if (subviewType == HistoryViewCell::SubviewType::PrettyPrint) {
       editController->setTextBody(calculation->text());
     } else {
-      char * resultText = calculation->evaluation()->text();
+      char resultText[Calculation::k_maximalExpressionTextLength];
+      calculation->evaluation()->writeTextInBuffer(resultText, Calculation::k_maximalExpressionTextLength);
       editController->setTextBody(resultText);
     }
     m_selectableTableView.deselectTable();
@@ -64,7 +64,8 @@ bool HistoryController::handleEvent(Ion::Events::Event event) {
     if (subviewType == HistoryViewCell::SubviewType::PrettyPrint) {
       newCalculation = *calculation;
     } else {
-      char * resultText = calculation->evaluation()->text();
+      char resultText[Calculation::k_maximalExpressionTextLength];
+      calculation->evaluation()->writeTextInBuffer(resultText, Calculation::k_maximalExpressionTextLength);
       /* TODO: this will work when we will parse float */
       //App * calculationApp = (App *)app();
       //newCalculation.setContent(resultText, calculationApp->evaluateContext());

poincare/include/poincare/expression.h

@@ -69,11 +69,7 @@ class Expression {
      * Do not forget to delete the new expression to avoid leaking. */
     virtual Expression * evaluate(Context& context) const = 0;
     virtual float approximate(Context& context) const = 0;
-    char * text();
-  protected:
-    virtual void setText();
-    constexpr static int k_maxLength = 255;
-    char m_text[k_maxLength];
+    virtual int writeTextInBuffer(char * buffer, int bufferSize);
   private:
     bool sequentialOperandsIdentity(const Expression * e) const;
     bool commutativeOperandsIdentity(const Expression * e) const;

poincare/include/poincare/float.h

@@ -20,10 +20,10 @@ public:
   };
   void setNumberOfDigitsInMantissa(int numberOfDigits);
   /* The parameter 'DisplayMode' refers to the way to display float 'scientific' or
-   * 'decimal'. The code only handles 'scientific' so far. */
-  void convertFloatToText(char * buffer, int bufferSize, int numberOfDigitsInMantissa, DisplayMode mode = DisplayMode::Scientific) const;
-protected:
-  void setText() override;
+   * 'decimal'. The code only handles 'scientific' so far. If the buffer size is
+   * small, the function does nothing. */
+  int convertFloatToText(char * buffer, int bufferSize, int numberOfDigitsInMantissa, DisplayMode mode = DisplayMode::Scientific) const;
+  int writeTextInBuffer(char * buffer, int bufferSize) override;
 private:
   constexpr static int k_maxBufferLength = 14;
   /* This function prints the int i in the buffer with a '.' at the position

poincare/include/poincare/matrix.h

@@ -21,8 +21,9 @@ class Matrix : public Expression {
         int numberOfOperands, bool cloneOperands = true) const override;
     int numberOfRows() const;
     int numberOfColumns() const;
-  protected:
-    void setText() override;
+    /* If the buffer is too small, the function fills the buffer until reaching
+     * buffer size */
+    int writeTextInBuffer(char * buffer, int bufferSize) override;
   private:
     MatrixData * m_matrixData;
     static Integer * defaultExpression();

poincare/src/expression.cpp

@@ -171,10 +171,6 @@ bool Expression::isCommutative() const {
   return false;
 }
 
-void Expression::setText() {
-}
-
-char * Expression::text() {
-  setText();
-  return m_text;
+int Expression::writeTextInBuffer(char * buffer, int bufferSize) {
+  return 0;
 }

poincare/src/float.cpp

@@ -49,8 +49,8 @@ bool Float::valueEquals(const Expression * e) const {
   return m_float == ((Float *)e)->m_float;
 }
 
-void Float::setText() {
-  convertFloatToText(m_text, k_maxBufferLength, m_numberOfDigitsInMantissa);
+int Float::writeTextInBuffer(char * buffer, int bufferSize) {
+  return convertFloatToText(buffer, bufferSize, m_numberOfDigitsInMantissa);
 }
 
 void Float::printBase10IntegerWithDecimalMarker(char * buffer, int bufferSize,  int i, int decimalMarkerPosition) {
@@ -78,12 +78,15 @@ void Float::printBase10IntegerWithDecimalMarker(char * buffer, int bufferSize,
   }  while (endChar >= startChar);
 }
 
-void Float::convertFloatToText(char * buffer, int bufferSize,
+int Float::convertFloatToText(char * buffer, int bufferSize,
     int numberOfDigitsInMantissa, DisplayMode mode) const {
   /* We here assert that the buffer is long enough to display with the right
    * number of digits in the mantissa. If numberOfDigitsInMantissa = 7, the
    * worst case has the form -1.999999e-38 (7+6+1 char). */
-  assert(bufferSize > 6 + numberOfDigitsInMantissa);
+  if (bufferSize <= 6 + numberOfDigitsInMantissa) {
+    buffer[0] = 0;
+    return 0;
+  }
 
   if (isinf(m_float)) {
     buffer[0] = m_float > 0 ? '+' : '-';
@@ -91,7 +94,7 @@ void Float::convertFloatToText(char * buffer, int bufferSize,
     buffer[2] = 'n';
     buffer[3] = 'f';
     buffer[4] = 0;
-    return;
+    return 5;
   }
 
   if (isnan(m_float)) {
@@ -99,7 +102,7 @@ void Float::convertFloatToText(char * buffer, int bufferSize,
     buffer[1] = 'a';
     buffer[2] = 'N';
     buffer[3] = 0;
-    return;
+    return 4;
   }
 
   float logBase10 = m_float != 0.0f ? log10f(fabsf(m_float)) : 0;
@@ -154,4 +157,5 @@ void Float::convertFloatToText(char * buffer, int bufferSize,
   buffer[availableCharsForMantissaWithSign] = 'e';
   printBase10IntegerWithDecimalMarker(buffer+availableCharsForMantissaWithSign+1, numberOfCharExponent, exponentInBase10, -1);
   buffer[availableCharsForMantissaWithSign+1+numberOfCharExponent] = 0;
+  return (availableCharsForMantissaWithSign+1+numberOfCharExponent);
 }

poincare/src/matrix.cpp

@@ -79,22 +79,48 @@ int Matrix::numberOfColumns() const {
   return m_matrixData->numberOfColumns();
 }
 
-void Matrix::setText() {
+int Matrix::writeTextInBuffer(char * buffer, int bufferSize) {
+  buffer[bufferSize] = 0;
   int currentChar = 0;
-  m_text[currentChar++] = '[';
-  for (int i = 0; i < m_matrixData->numberOfRows(); i++) {
-    m_text[currentChar++] = '[';
-    char * operandText = m_matrixData->operands()[i*m_matrixData->numberOfColumns()]->text();
-    strlcpy(m_text+currentChar, operandText, strlen(operandText)+1);
-    for (int j = 1; j < numberOfColumns(); j++) {
-      currentChar += strlen(operandText);
-      m_text[currentChar++] = ',';
-      operandText = m_matrixData->operands()[i*m_matrixData->numberOfColumns()+j]->text();
-      strlcpy(m_text+currentChar, operandText, strlen(operandText)+1);
-    }
-    currentChar += strlen(operandText);
-    m_text[currentChar++] = ']';
+  if (currentChar >= bufferSize) {
+    return 0;
   }
-  m_text[currentChar++] = ']';
-  m_text[currentChar] = 0;
+  buffer[currentChar++] = '[';
+  if (currentChar >= bufferSize) {
+    return currentChar;
+  }
+  for (int i = 0; i < m_matrixData->numberOfRows(); i++) {
+    buffer[currentChar++] = '[';
+    if (currentChar >= bufferSize) {
+      return currentChar;
+    }
+    currentChar += m_matrixData->operands()[i*m_matrixData->numberOfColumns()]->writeTextInBuffer(buffer+currentChar, bufferSize-currentChar);
+    if (currentChar >= bufferSize) {
+      return currentChar;
+    }
+    for (int j = 1; j < numberOfColumns(); j++) {
+      buffer[currentChar++] = ',';
+      if (currentChar >= bufferSize) {
+        return currentChar;
+      }
+      currentChar += m_matrixData->operands()[i*m_matrixData->numberOfColumns()+j]->writeTextInBuffer(buffer+currentChar, bufferSize-currentChar);
+      if (currentChar >= bufferSize) {
+        return currentChar;
+      }
+    }
+    currentChar = strlen(buffer);
+    if (currentChar >= bufferSize) {
+      return currentChar;
+    }
+    buffer[currentChar++] = ']';
+    if (currentChar >= bufferSize) {
+      return currentChar;
+    }
+  }
+  buffer[currentChar++] = ']';
+  if (currentChar >= bufferSize) {
+    return currentChar;
+  }
+  buffer[currentChar] = 0;
+  return currentChar;
 }