[poincare] Fix VerticalOffsetLayout serialization

"2^3 !" would be serialized as "2^3*!", which is wrong. It is now serialized
as "2 Ion::Charset::Superscript 3 Ion::Charset::Superscript !" and
parsed correctly.

ion/include/ion/charset.h

@@ -27,7 +27,8 @@ enum Charset : char {
   MiddleDot = (char)149,
   AlmostEqual = (char)150,
   Degree = (char)151,
-  Empty = (char)152 // This char is used to be parsed into EmptyExpression.
+  Empty = (char)152, // This char is used to be parsed into EmptyExpression
+  Superscript = (char)153 // This char is used to parse Power
 };
 
 }

poincare/src/parsing/parser.cpp

@@ -54,6 +54,7 @@ Expression Parser::parseUntil(Token::Type stoppingType) {
     &Parser::parseUnexpected,      // Token::EndOfStream
     &Parser::parseStore,           // Token::Store
     &Parser::parseEqual,           // Token::Equal
+    &Parser::parseSuperscript,     // Token::Superscript
     &Parser::parseUnexpected,      // Token::RightBracket
     &Parser::parseUnexpected,      // Token::RightParenthesis
     &Parser::parseUnexpected,      // Token::RightBrace
@@ -250,6 +251,23 @@ void Parser::parseStore(Expression & leftHandSide) {
   leftHandSide = Store(leftHandSide, static_cast<SymbolAbstract&>(rightHandSide));
 }
 
+void Parser::parseSuperscript(Expression & leftHandSide) {
+  if (leftHandSide.isUninitialized()) {
+    m_status = Status::Error; // Power must have a left operand
+    return;
+  }
+  Expression rightHandSide = parseUntil(Token::Superscript);
+  if (m_status != Status::Progress) {
+    return;
+  }
+  if (!popTokenIfType(Token::Superscript)) {
+    m_status = Status::Error; // Right superscript marker missing.
+    return;
+  }
+  leftHandSide = Power(leftHandSide, rightHandSide);
+  isThereImplicitMultiplication();
+}
+
 bool Parser::parseBinaryOperator(const Expression & leftHandSide, Expression & rightHandSide, Token::Type stoppingType) {
   if (leftHandSide.isUninitialized()) {
     m_status = Status::Error; // Left-hand side missing.

poincare/src/parsing/parser.h

@@ -61,6 +61,7 @@ private:
   void parseCaret(Expression & leftHandSide);
   void parseEqual(Expression & leftHandSide);
   void parseStore(Expression & leftHandSide);
+  void parseSuperscript(Expression & leftHandSide);
 
   // Parsing helpers
   bool parseBinaryOperator(const Expression & leftHandSide, Expression & rightHandSide, Token::Type stoppingType);

poincare/src/parsing/token.h

@@ -24,6 +24,9 @@ public:
        * token of lesser precedence than Equal, and this prevents expressions
        * such as "3=4>a". Tokenizer::parseStore uses a special algorithm that
        * prevents (3>4=a). */
+    Superscript,
+      /* Superscript marks the limit of a power. For instance:
+       * 2 Superscript 3! Superscript ! is (2^(3!))! */
     RightBracket,
     RightParenthesis,
     RightBrace,

poincare/src/parsing/tokenizer.cpp

@@ -122,6 +122,12 @@ Token Tokenizer::popToken() {
   if (currentChar == Ion::Charset::MultiplicationSign || currentChar == Ion::Charset::MiddleDot) {
     return Token(Token::Times);
   }
+  if (currentChar == '^') {
+    return Token(Token::Caret);
+  }
+  if (currentChar == Ion::Charset::Superscript) {
+    return Token(Token::Superscript);
+  }
   if (currentChar == '!') {
     return Token(Token::Bang);
   }
@@ -134,9 +140,6 @@ Token Tokenizer::popToken() {
   if (currentChar == ']') {
     return Token(Token::RightBracket);
   }
-  if (currentChar == '^') {
-    return Token(Token::Caret);
-  }
   if (currentChar == '{') {
     return Token(Token::LeftBrace);
   }

poincare/src/vertical_offset_layout.cpp

@@ -174,20 +174,14 @@ int VerticalOffsetLayoutNode::serialize(char * buffer, int bufferSize, Preferenc
     return numberOfChar;
   }
   assert(m_type == Type::Superscript);
-  // If the layout is a superscript, write "^(indice)"
-  int numberOfChar = SerializationHelper::Prefix(this, buffer, bufferSize, floatDisplayMode, numberOfSignificantDigits, "^");
+  // If the layout is a superscript, write "Ion::Charset::Superscript indice Ion::Charset::Superscript"
+  int numberOfChar = SerializationHelper::Char(buffer, bufferSize, Ion::Charset::Superscript);
+  if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
+  numberOfChar += const_cast<VerticalOffsetLayoutNode *>(this)->indiceLayout()->serialize(buffer+numberOfChar, bufferSize-numberOfChar, floatDisplayMode, numberOfSignificantDigits);
+  if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
+  numberOfChar += SerializationHelper::Char(buffer+numberOfChar, bufferSize-numberOfChar, Ion::Charset::Superscript);
   if (numberOfChar >= bufferSize-1) { return bufferSize-1; }
 
-  // Add a multiplication if omitted.
-  int indexInParent = -1;
-  LayoutNode * parentNode = parent();
-  if (parentNode != nullptr) {
-    indexInParent = parentNode->indexOfChild(this);
-  }
-  if (indexInParent >= 0 && indexInParent < (parentNode->numberOfChildren() - 1) && parentNode->isHorizontal() && parentNode->childAtIndex(indexInParent + 1)->canBeOmittedMultiplicationRightFactor()) {
-    buffer[numberOfChar++] = Ion::Charset::MiddleDot;
-    if (numberOfChar >= bufferSize-1) { return bufferSize-1;}
-  }
   buffer[numberOfChar] = 0;
   return numberOfChar;
 }