[poincare] Add NullStatus for expressions

Change-Id: Ibaba72e3e3589ba259c7b22d402e2b27937f27c1

poincare/include/poincare/based_integer.h

@@ -28,7 +28,7 @@ public:
   // Expression subclassing
   Type type() const override { return Type::BasedInteger; }
   Sign sign(Context * context) const override { return Sign::Positive; }
-  bool isNumberZero() const override { return integer().isZero(); }
+  NullStatus nullStatus(Context * context) const override { return integer().isZero() ? NullStatus::Null : NullStatus::NonNull; }
 
   // Layout
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;

poincare/include/poincare/constant.h

@@ -28,6 +28,7 @@ public:
   // Expression Properties
   Type type() const override { return Type::Constant; }
   Sign sign(Context * context) const override;
+  NullStatus nullStatus(Context * context) const override { return NullStatus::NonNull; }
 
   /* Layout */
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;

poincare/include/poincare/decimal.h

@@ -42,8 +42,8 @@ public:
   // Properties
   Type type() const override { return Type::Decimal; }
   Sign sign(Context * context) const override { return m_negative ? Sign::Negative : Sign::Positive; }
+  NullStatus nullStatus(Context * context) const override { return unsignedMantissa().isZero() ? NullStatus::Null : NullStatus::NonNull; }
   Expression setSign(Sign s, ReductionContext reductionContext) override;
-  bool isNumberZero() const override { return unsignedMantissa().isZero(); }
 
   // Approximation
   Evaluation<float> approximate(SinglePrecision p, Context * context, Preferences::ComplexFormat complexFormat, Preferences::AngleUnit angleUnit) const override {

poincare/include/poincare/expression.h

@@ -151,9 +151,10 @@ public:
   ExpressionNode::Type type() const { return node()->type(); }
   bool isOfType(ExpressionNode::Type * types, int length) const { return node()->isOfType(types, length); }
   ExpressionNode::Sign sign(Context * context) const { return node()->sign(context); }
+  ExpressionNode::NullStatus nullStatus(Context * context) const { return node()->nullStatus(context); }
+  bool isStrictly(ExpressionNode::Sign s, Context * context) const { return s == node()->sign(context) && node()->nullStatus(context) == ExpressionNode::NullStatus::NonNull;  }
   bool isUndefined() const { return node()->type() == ExpressionNode::Type::Undefined ||  node()->type() == ExpressionNode::Type::Unreal; }
   bool isNumber() const { return node()->isNumber(); }
-  bool isNumberZero() const { return node()->isNumberZero(); }
   bool isRationalOne() const;
   bool isRandom() const { return node()->isRandom(); }
   bool isParameteredExpression() const { return node()->isParameteredExpression(); }

poincare/include/poincare/expression_node.h

@@ -156,6 +156,11 @@ public:
     Unknown = 0,
     Positive = 1
   };
+  enum class NullStatus {
+    Unknown = -1,
+    NonNull = 0,
+    Null = 1,
+  };
 
   class ReductionContext {
   public:
@@ -186,8 +191,8 @@ public:
   };
 
   virtual Sign sign(Context * context) const { return Sign::Unknown; }
+  virtual NullStatus nullStatus(Context * context) const { return NullStatus::Unknown; }
   virtual bool isNumber() const { return false; }
-  virtual bool isNumberZero() const { return false; }
   virtual bool isRandom() const { return false; }
   virtual bool isParameteredExpression() const { return false; }
   /* childAtIndexNeedsUserParentheses checks if parentheses are required by mathematical rules:

poincare/include/poincare/float.h

@@ -38,9 +38,9 @@ public:
   // Properties
   Type type() const override { return (sizeof(T) == sizeof(float)) ? Type::Float : Type::Double; }
   Sign sign(Context * context) const override { return m_value < 0 ? Sign::Negative : Sign::Positive; }
+  NullStatus nullStatus(Context * context) const override { return m_value == 0.0 ? NullStatus::Null : NullStatus::NonNull; }
   Expression setSign(Sign s, ReductionContext reductionContext) override;
   int simplificationOrderSameType(const ExpressionNode * e, bool ascending, bool canBeInterrupted, bool ignoreParentheses) const override;
-  bool isNumberZero() const override { return m_value == 0.0; }
 
   // Layout
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;

poincare/include/poincare/hyperbolic_arc_cosine.h

@@ -21,7 +21,7 @@ public:
   Type type() const override { return Type::HyperbolicArcCosine; }
 private:
   // Simplification
-  bool isNotableValue(Expression e) const override { return e.isRationalOne(); }
+  bool isNotableValue(Expression e, Context * context) const override { return e.isRationalOne(); }
   // Layout
   Layout createLayout(Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;
   int serialize(char * buffer, int bufferSize, Preferences::PrintFloatMode floatDisplayMode, int numberOfSignificantDigits) const override;

poincare/include/poincare/hyperbolic_trigonometric_function.h

@@ -17,7 +17,7 @@ private:
   LayoutShape leftLayoutShape() const override { return LayoutShape::MoreLetters; };
   LayoutShape rightLayoutShape() const override { return LayoutShape::BoundaryPunctuation; }
   Expression shallowReduce(ReductionContext reductionContext) override;
-  virtual bool isNotableValue(Expression e) const { return e.isNumberZero(); }
+  virtual bool isNotableValue(Expression e, Context * context) const { return e.nullStatus(context) == ExpressionNode::NullStatus::Null; }
   virtual Expression imageOfNotableValue() const { return Rational::Builder(0); }
 };
 

poincare/include/poincare/infinity.h

@@ -23,6 +23,7 @@ public:
   // Properties
   Type type() const override { return Type::Infinity; }
   Sign sign(Context * context) const override { return m_negative ? Sign::Negative : Sign::Positive; }
+  NullStatus nullStatus(Context * context) const override { return NullStatus::NonNull; }
   Expression setSign(Sign s, ReductionContext reductionContext) override;
 
   // Approximation

poincare/include/poincare/rational.h

@@ -17,7 +17,7 @@ public:
   bool isNegative() const { return m_negative; }
   void setNegative(bool negative) { m_negative = negative; }
   bool isInteger() const { return denominator().isOne(); }
-  bool isNumberZero() const override { return isZero(); }
+  NullStatus nullStatus(Context * context) const override { return isZero() ? NullStatus::Null : NullStatus::NonNull; }
 
   // TreeNode
   size_t size() const override;