[apps/shared/text_field_delegate_app] Refuse Equal

The Equal sign now triggers a syntax error in all apps but Solver. This
make its behaviour symmetrical with that of < and >.

Change-Id: Ia886c547a315d5627a69f3f2acac2cbce0e202c2

apps/calculation/app.cpp

@@ -68,7 +68,7 @@ bool App::isAcceptableExpression(const Poincare::Expression expression) {
       return false;
     }
   }
-  return !expression.isUninitialized();
+  return !(expression.isUninitialized() || expression.type() == ExpressionNode::Type::Equal);
 }
 
 void App::didBecomeActive(Window * window) {

apps/shared/function_app.cpp

@@ -37,13 +37,9 @@ void FunctionApp::willBecomeInactive() {
   ::App::willBecomeInactive();
 }
 
-bool FunctionApp::isAcceptableExpression(const Poincare::Expression expression) {
-  /* We forbid functions whose type is equal because the input "2+f(3)" would be
-   * simplify to an expression with an nested equal node which makes no sense. */
-  if (!TextFieldDelegateApp::ExpressionCanBeSerialized(expression, false, Expression(), localContext()) || expression.type() == ExpressionNode::Type::Equal) {
-    return false;
-  }
-  return TextFieldDelegateApp::isAcceptableExpression(expression);
+
+bool FunctionApp::isAcceptableExpression(const Expression exp) {
+ return TextFieldDelegateApp::isAcceptableExpression(exp) && ExpressionCanBeSerialized(exp, false, Expression(), localContext());
 }
 
 }

apps/shared/text_field_delegate_app.cpp

@@ -85,13 +85,7 @@ bool TextFieldDelegateApp::isFinishingEvent(Ion::Events::Event event) {
 }
 
 bool TextFieldDelegateApp::isAcceptableExpression(const Expression exp) {
-  if (exp.isUninitialized()) {
-    return false;
-  }
-  if (exp.type() == ExpressionNode::Type::Store) {
-    return false;
-  }
-  return true;
+  return !(exp.isUninitialized() || exp.type() == ExpressionNode::Type::Store || exp.type() == ExpressionNode::Type::Equal);
 }
 
 bool TextFieldDelegateApp::ExpressionCanBeSerialized(const Expression expression, bool replaceAns, Expression ansExpression, Context * context) {

apps/solver/app.cpp

@@ -64,4 +64,10 @@ void App::willBecomeInactive() {
   ::App::willBecomeInactive();
 }
 
+
+bool App::isAcceptableExpression(const Poincare::Expression exp) {
+  return TextFieldDelegateApp::ExpressionCanBeSerialized(exp, false, Poincare::Expression(), localContext())
+      && !(exp.isUninitialized() || exp.type() == Poincare::ExpressionNode::Type::Store);
+}
+
 }

apps/solver/app.h

@@ -46,6 +46,9 @@ public:
   void willBecomeInactive() override;
   TELEMETRY_ID("Solver");
 private:
+  // TextFieldDelegateApp
+  bool isAcceptableExpression(const Poincare::Expression expression) override;
+
   App(Snapshot * snapshot);
   SolutionsController m_solutionsController;
   IntervalController m_intervalController;