Formulas: Added parentheses to formula output to avoid ambiguity

src/storm/logic/AtomicExpressionFormula.cpp

@@ -28,8 +28,15 @@ namespace storm {
             expression.gatherVariables(usedVariables);
         }
         
-        std::ostream& AtomicExpressionFormula::writeToStream(std::ostream& out) const {
+        std::ostream& AtomicExpressionFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
+            bool parentheses = allowParentheses & (this->expression.isLiteral() || this->expression.isVariable());
+            if (parentheses) {
+                out << "(";
+            }
             out << expression;
+            if (parentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/AtomicExpressionFormula.h

@@ -19,7 +19,7 @@ namespace storm {
             
             storm::expressions::Expression const& getExpression() const;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
             virtual void gatherAtomicExpressionFormulas(std::vector<std::shared_ptr<AtomicExpressionFormula const>>& atomicExpressionFormulas) const override;
             virtual void gatherUsedVariables(std::set<storm::expressions::Variable>& usedVariables) const override;

src/storm/logic/AtomicLabelFormula.cpp

@@ -25,7 +25,8 @@ namespace storm {
             atomicExpressionFormulas.push_back(std::dynamic_pointer_cast<AtomicLabelFormula const>(this->shared_from_this()));
         }
         
-        std::ostream& AtomicLabelFormula::writeToStream(std::ostream& out) const {
+        std::ostream& AtomicLabelFormula::writeToStream(std::ostream& out, bool /*allowParentheses*/) const {
+            // No parentheses necessary
             out << "\"" << label << "\"";
             return out;
         }

src/storm/logic/AtomicLabelFormula.h

@@ -23,7 +23,7 @@ namespace storm {
             
             virtual void gatherAtomicLabelFormulas(std::vector<std::shared_ptr<AtomicLabelFormula const>>& atomicLabelFormulas) const override;
                         
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
                         
         private:
             std::string label;

src/storm/logic/BinaryBooleanPathFormula.cpp

@@ -41,15 +41,19 @@ namespace storm {
             return this->getOperator() == OperatorType::Or;
         }
                 
-        std::ostream& BinaryBooleanPathFormula::writeToStream(std::ostream& out) const {
+        std::ostream& BinaryBooleanPathFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
-            out << "(";
+            if (allowParentheses) {
-            this->getLeftSubformula().writeToStream(out);
+                out << "(";
+            }
+            this->getLeftSubformula().writeToStream(out, true);
             switch (operatorType) {
                 case OperatorType::And: out << " & "; break;
                 case OperatorType::Or: out << " | "; break;
             }
-            this->getRightSubformula().writeToStream(out);
+            this->getRightSubformula().writeToStream(out, true);
-            out << ")";
+            if (allowParentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/BinaryBooleanPathFormula.h

@@ -31,7 +31,7 @@ namespace storm {
             virtual bool isAnd() const;
             virtual bool isOr() const;
                         
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
         private:
             OperatorType operatorType;

src/storm/logic/BinaryBooleanStateFormula.cpp

@@ -31,15 +31,19 @@ namespace storm {
             return this->getOperator() == OperatorType::Or;
         }
                 
-        std::ostream& BinaryBooleanStateFormula::writeToStream(std::ostream& out) const {
+        std::ostream& BinaryBooleanStateFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
-            out << "(";
+            if (allowParentheses) {
-            this->getLeftSubformula().writeToStream(out);
+                out << "(";
+            }
+            this->getLeftSubformula().writeToStream(out, true);
             switch (operatorType) {
                 case OperatorType::And: out << " & "; break;
                 case OperatorType::Or: out << " | "; break;
             }
-            this->getRightSubformula().writeToStream(out);
+            this->getRightSubformula().writeToStream(out, true);
-            out << ")";
+            if (allowParentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/BinaryBooleanStateFormula.h

@@ -27,7 +27,7 @@ namespace storm {
             virtual bool isAnd() const;
             virtual bool isOr() const;
                         
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
         private:
             OperatorType operatorType;

src/storm/logic/BooleanLiteralFormula.cpp

@@ -24,7 +24,8 @@ namespace storm {
             return visitor.visit(*this, data);
         }
         
-        std::ostream& BooleanLiteralFormula::writeToStream(std::ostream& out) const {
+        std::ostream& BooleanLiteralFormula::writeToStream(std::ostream& out, bool /*allowParentheses */) const {
+            // No parentheses necessary
             if (value) {
                 out << "true";
             } else {

src/storm/logic/BooleanLiteralFormula.h

@@ -19,7 +19,7 @@ namespace storm {
             
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
                         
         private:
             bool value;

src/storm/logic/BoundedUntilFormula.cpp

@@ -309,7 +309,7 @@ namespace storm {
             return std::make_shared<BoundedUntilFormula const>(getLeftSubformula(i).asSharedPointer(), getRightSubformula(i).asSharedPointer(), lowerBound.at(i), upperBound.at(i), getTimeBoundReference(i));
         }
 
-        std::ostream& BoundedUntilFormula::writeToStream(std::ostream& out) const {
+        std::ostream& BoundedUntilFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
             if (hasMultiDimensionalSubformulas()) {
                 out << "multi(";
                 restrictToDimension(0)->writeToStream(out);
@@ -319,8 +319,10 @@ namespace storm {
                 }
                 out << ")";
             } else {
-                
+                if (allowParentheses) {
-                this->getLeftSubformula().writeToStream(out);
+                    out << "(";
+                }
+                this->getLeftSubformula().writeToStream(out, true);
                 
                 out << " U";
                 if (this->isMultiDimensional()) {
@@ -379,7 +381,10 @@ namespace storm {
                     out << "}";
                 }
                 
-                this->getRightSubformula().writeToStream(out);
+                this->getRightSubformula().writeToStream(out, true);
+                if (allowParentheses) {
+                    out << ")";
+                }
             }
             
             return out;

src/storm/logic/BoundedUntilFormula.h

@@ -67,7 +67,7 @@ namespace storm {
 
             std::shared_ptr<BoundedUntilFormula const> restrictToDimension(unsigned i) const;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
         private:
             static void checkNoVariablesInBound(storm::expressions::Expression const& bound);

src/storm/logic/ConditionalFormula.cpp

@@ -62,10 +62,16 @@ namespace storm {
             return true;
         }
         
-        std::ostream& ConditionalFormula::writeToStream(std::ostream& out) const {
+        std::ostream& ConditionalFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
-            this->getSubformula().writeToStream(out);
+            if (allowParentheses) {
+                out << "(";
+            }
+            this->getSubformula().writeToStream(out, true);
             out << " || ";
-            this->getConditionFormula().writeToStream(out);
+            this->getConditionFormula().writeToStream(out, true);
+            if (allowParentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/ConditionalFormula.h

@@ -23,7 +23,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
 
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
             virtual void gatherAtomicExpressionFormulas(std::vector<std::shared_ptr<AtomicExpressionFormula const>>& atomicExpressionFormulas) const override;
             virtual void gatherAtomicLabelFormulas(std::vector<std::shared_ptr<AtomicLabelFormula const>>& atomicLabelFormulas) const override;

src/storm/logic/CumulativeRewardFormula.cpp

@@ -161,7 +161,8 @@ namespace storm {
             return std::make_shared<CumulativeRewardFormula const>(bounds.at(i), getTimeBoundReference(i), rewardAccumulation);
         }
         
-        std::ostream& CumulativeRewardFormula::writeToStream(std::ostream& out) const {
+        std::ostream& CumulativeRewardFormula::writeToStream(std::ostream& out, bool /*allowParentheses*/ ) const {
+            // No parentheses necessary
             out << "C";
             if (hasRewardAccumulation()) {
                 out << "[" << getRewardAccumulation() << "]";

src/storm/logic/CumulativeRewardFormula.h

@@ -26,7 +26,7 @@ namespace storm {
             virtual void gatherReferencedRewardModels(std::set<std::string>& referencedRewardModels) const override;
             virtual void gatherUsedVariables(std::set<storm::expressions::Variable>& usedVariables) const override;
 
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
             TimeBoundReference const& getTimeBoundReference() const;
             TimeBoundReference const& getTimeBoundReference(unsigned i) const;

src/storm/logic/EventuallyFormula.cpp

@@ -55,12 +55,18 @@ namespace storm {
             return visitor.visit(*this, data);
         }
                 
-        std::ostream& EventuallyFormula::writeToStream(std::ostream& out) const {
+        std::ostream& EventuallyFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
+            if (allowParentheses) {
+                out << "(";
+            }
             out << "F ";
             if (hasRewardAccumulation()) {
                 out << "[" << getRewardAccumulation() << "]";
             }
-            this->getSubformula().writeToStream(out);
+            this->getSubformula().writeToStream(out, !this->getSubformula().isUnaryFormula());
+            if (allowParentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/EventuallyFormula.h

@@ -29,7 +29,7 @@ namespace storm {
             
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
 
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             bool hasRewardAccumulation() const;
             RewardAccumulation const& getRewardAccumulation() const;
             

src/storm/logic/Formula.cpp

@@ -179,6 +179,10 @@ namespace storm {
         bool Formula::isOperatorFormula() const {
             return false;
         }
+        
+        bool Formula::isUnaryFormula() const {
+            return isUnaryPathFormula() || isUnaryStateFormula();
+        }
 
         bool Formula::hasQualitativeResult() const {
             return true;

src/storm/logic/Formula.h

@@ -94,6 +94,7 @@ namespace storm {
             virtual bool isBinaryStateFormula() const;
             virtual bool isUnaryPathFormula() const;
             virtual bool isUnaryStateFormula() const;
+            bool isUnaryFormula() const;
 
             // Accessors for the return type of a formula.
             virtual bool hasQualitativeResult() const;
@@ -236,7 +237,14 @@ namespace storm {
             storm::expressions::Expression toExpression(storm::expressions::ExpressionManager const& manager, std::map<std::string, storm::expressions::Expression> const& labelToExpressionMapping = {}) const;
 
             std::string toString() const;
-            virtual std::ostream& writeToStream(std::ostream& out) const = 0;
+            /*!
+             * Writes the forumla to the given output stream
+             * @param allowParenthesis if true, the output is *potentially* surrounded by parentheses depending on whether parentheses are needed to avoid ambiguity when this formula appears as a subformula of some larger formula.
+             * @return
+             */
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const = 0;
+            
             std::string toPrefixString() const;
 
             virtual void gatherAtomicExpressionFormulas(std::vector<std::shared_ptr<AtomicExpressionFormula const>>& atomicExpressionFormulas) const;

src/storm/logic/GameFormula.cpp

@@ -32,9 +32,10 @@ namespace storm {
             return visitor.visit(*this, data);
         }
 
-        std::ostream& GameFormula::writeToStream(std::ostream& out) const {
+        std::ostream& GameFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parenthesis necessary
             out << "<<" << coalition << ">> ";
-            this->getSubformula().writeToStream(out);
+            this->getSubformula().writeToStream(out, true);
             return out;
         }
     }

src/storm/logic/GameFormula.h

@@ -24,7 +24,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
 
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
 
         private:
             PlayerCoalition coalition;

src/storm/logic/GloballyFormula.cpp

@@ -20,9 +20,15 @@ namespace storm {
             return visitor.visit(*this, data);
         }
         
-        std::ostream& GloballyFormula::writeToStream(std::ostream& out) const {
+        std::ostream& GloballyFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
+            if (allowParentheses) {
+                out << "(";
+            }
             out << "G ";
-            this->getSubformula().writeToStream(out);
+            this->getSubformula().writeToStream(out, !this->getSubformula().isUnaryFormula());
+            if (allowParentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/GloballyFormula.h

@@ -18,7 +18,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
         };
     }
 }

src/storm/logic/HOAPathFormula.cpp

@@ -76,7 +76,8 @@ namespace storm {
         }
 
 
-        std::ostream& HOAPathFormula::writeToStream(std::ostream& out) const {
+        std::ostream& HOAPathFormula::writeToStream(std::ostream& out, bool /* allowParentheses */ ) const {
+            // No parentheses necessary
             out << "HOA: { ";
             out << "\"" <<  automatonFile << "\"";
             for (auto& mapping : apToFormulaMap) {

src/storm/logic/HOAPathFormula.h

@@ -39,7 +39,7 @@ namespace storm {
             virtual void gatherAtomicLabelFormulas(std::vector<std::shared_ptr<AtomicLabelFormula const>>& atomicLabelFormulas) const override;
             virtual void gatherReferencedRewardModels(std::set<std::string>& referencedRewardModels) const override;
 
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
 
 	    std::shared_ptr<storm::automata::DeterministicAutomaton> readAutomaton() const;
 

src/storm/logic/InstantaneousRewardFormula.cpp

@@ -68,7 +68,8 @@ namespace storm {
             STORM_LOG_THROW(!bound.containsVariables(), storm::exceptions::InvalidOperationException, "Cannot evaluate time-instant '" << bound << "' as it contains undefined constants.");
         }
         
-        std::ostream& InstantaneousRewardFormula::writeToStream(std::ostream& out) const {
+        std::ostream& InstantaneousRewardFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary.
             out << "I=" << this->getBound();
             return out;
         }

src/storm/logic/InstantaneousRewardFormula.h

@@ -22,7 +22,7 @@ namespace storm {
             
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
             TimeBoundType const& getTimeBoundType() const;
             bool isStepBounded() const;

src/storm/logic/LongRunAverageOperatorFormula.cpp

@@ -18,10 +18,11 @@ namespace storm {
         boost::any LongRunAverageOperatorFormula::accept(FormulaVisitor const& visitor, boost::any const& data) const {
             return visitor.visit(*this, data);
         }
-                
+        std::ostream& LongRunAverageOperatorFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
-        std::ostream& LongRunAverageOperatorFormula::writeToStream(std::ostream& out) const {
+            // No parentheses necessary
             out << "LRA";
-            OperatorFormula::writeToStream(out);
+            OperatorFormula::writeToStream(out, false);
             return out;
         }
     }

src/storm/logic/LongRunAverageOperatorFormula.h

@@ -17,7 +17,7 @@ namespace storm {
             
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
         };
     }
 }

src/storm/logic/LongRunAverageRewardFormula.cpp

@@ -32,7 +32,8 @@ namespace storm {
             return visitor.visit(*this, data);
         }
         
-        std::ostream& LongRunAverageRewardFormula::writeToStream(std::ostream& out) const {
+        std::ostream& LongRunAverageRewardFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             out << "LRA";
             if (hasRewardAccumulation()) {
                 out << "[" << getRewardAccumulation() << "]";

src/storm/logic/LongRunAverageRewardFormula.h

@@ -23,7 +23,7 @@ namespace storm {
             
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
 
         private:
             boost::optional<RewardAccumulation> rewardAccumulation;

src/storm/logic/MultiObjectiveFormula.cpp

@@ -84,7 +84,8 @@ namespace storm {
             }
         }
         
-        std::ostream& MultiObjectiveFormula::writeToStream(std::ostream &out) const {
+        std::ostream& MultiObjectiveFormula::writeToStream(std::ostream &out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             out << "multi(";
             for(uint_fast64_t index = 0; index < this->getNumberOfSubformulas(); ++index){
                 if(index>0){

src/storm/logic/MultiObjectiveFormula.h

@@ -27,7 +27,7 @@ namespace storm {
             virtual void gatherAtomicLabelFormulas(std::vector<std::shared_ptr<AtomicLabelFormula const>>& atomicLabelFormulas) const override;
             virtual void gatherReferencedRewardModels(std::set<std::string>& referencedRewardModels) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
         private:
             std::vector<std::shared_ptr<Formula const>> subformulas;
         };

src/storm/logic/NextFormula.cpp

@@ -20,9 +20,15 @@ namespace storm {
             return visitor.visit(*this, data);
         }
                 
-        std::ostream& NextFormula::writeToStream(std::ostream& out) const {
+        std::ostream& NextFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
+            if (allowParentheses) {
+                out << "(";
+            }
             out << "X ";
-            this->getSubformula().writeToStream(out);
+            this->getSubformula().writeToStream(out, !this->getSubformula().isUnaryFormula());
+            if (allowParentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/NextFormula.h

@@ -18,7 +18,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
                         
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
         };
     }
 }

src/storm/logic/OperatorFormula.cpp

@@ -104,7 +104,8 @@ namespace storm {
             }
         }
         
-        std::ostream& OperatorFormula::writeToStream(std::ostream& out) const {
+        std::ostream& OperatorFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             if (hasOptimalityType()) {
                 out << (getOptimalityType() == OptimizationDirection::Minimize ? "min" : "max");
             }

src/storm/logic/OperatorFormula.h

@@ -56,7 +56,7 @@ namespace storm {
             
             virtual void gatherUsedVariables(std::set<storm::expressions::Variable>& usedVariables) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
         protected:
             OperatorInformation operatorInformation;

src/storm/logic/ProbabilityOperatorFormula.cpp

@@ -19,9 +19,10 @@ namespace storm {
             return visitor.visit(*this, data);
         }
                 
-        std::ostream& ProbabilityOperatorFormula::writeToStream(std::ostream& out) const {
+        std::ostream& ProbabilityOperatorFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             out << "P";
-            OperatorFormula::writeToStream(out);
+            OperatorFormula::writeToStream(out, false);
             return out;
         }
     }

src/storm/logic/ProbabilityOperatorFormula.h

@@ -17,7 +17,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
                         
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
         };
     }
 }

src/storm/logic/QuantileFormula.cpp

@@ -73,7 +73,8 @@ namespace storm {
             subformula->gatherReferencedRewardModels(referencedRewardModels);
         }
         
-        std::ostream& QuantileFormula::writeToStream(std::ostream& out) const {
+        std::ostream& QuantileFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             out << "quantile(";
             for (auto const& bv : boundVariables) {
                 out << bv.getName() << ", ";

src/storm/logic/QuantileFormula.h

@@ -29,7 +29,7 @@ namespace storm {
             virtual void gatherAtomicLabelFormulas(std::vector<std::shared_ptr<AtomicLabelFormula const>>& atomicLabelFormulas) const override;
             virtual void gatherReferencedRewardModels(std::set<std::string>& referencedRewardModels) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
         private:
             std::vector<storm::expressions::Variable> boundVariables;
             std::shared_ptr<Formula const> subformula;

src/storm/logic/RewardOperatorFormula.cpp

@@ -44,7 +44,8 @@ namespace storm {
             return rewardMeasureType;
         }
         
-        std::ostream& RewardOperatorFormula::writeToStream(std::ostream& out) const {
+        std::ostream& RewardOperatorFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             out << "R";
             out << "[" << rewardMeasureType << "]";
             if (this->hasRewardModelName()) {

src/storm/logic/RewardOperatorFormula.h

@@ -20,7 +20,7 @@ namespace storm {
 
             virtual void gatherReferencedRewardModels(std::set<std::string>& referencedRewardModels) const override;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
             /*!
              * Retrieves whether the reward model refers to a specific reward model.

src/storm/logic/TimeOperatorFormula.cpp

@@ -24,7 +24,8 @@ namespace storm {
             return rewardMeasureType;
         }
         
-        std::ostream& TimeOperatorFormula::writeToStream(std::ostream& out) const {
+        std::ostream& TimeOperatorFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             out << "T";
             out << "[" << rewardMeasureType << "]";
             OperatorFormula::writeToStream(out);

src/storm/logic/TimeOperatorFormula.h

@@ -19,7 +19,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
                         
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
             
             /*!
              * Retrieves the measure type of the operator.

src/storm/logic/TotalRewardFormula.cpp

@@ -32,7 +32,8 @@ namespace storm {
             return visitor.visit(*this, data);
         }
 
-        std::ostream& TotalRewardFormula::writeToStream(std::ostream& out) const {
+        std::ostream& TotalRewardFormula::writeToStream(std::ostream& out, bool /* allowParentheses */) const {
+            // No parentheses necessary
             out << "C";
             if (hasRewardAccumulation()) {
                 out << "[" << getRewardAccumulation() << "]";

src/storm/logic/TotalRewardFormula.h

@@ -24,7 +24,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
 
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
 
         private:
             boost::optional<RewardAccumulation> rewardAccumulation;

src/storm/logic/UnaryBooleanPathFormula.cpp

@@ -36,12 +36,17 @@ namespace storm {
             return this->getOperator() == OperatorType::Not;
         }
                 
-        std::ostream& UnaryBooleanPathFormula::writeToStream(std::ostream& out) const {
+        std::ostream& UnaryBooleanPathFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
+            if (allowParentheses) {
+                out << "(";
+            }
             switch (operatorType) {
-                case OperatorType::Not: out << "!("; break;
+                case OperatorType::Not: out << "!"; break;
+            }
+            this->getSubformula().writeToStream(out, !this->getSubformula().isUnaryFormula());
+            if (allowParentheses) {
+                out << ")";
             }
-            this->getSubformula().writeToStream(out);
-            out << ")";
             return out;
         }
     }

src/storm/logic/UnaryBooleanPathFormula.h

@@ -28,7 +28,7 @@ namespace storm {
             
             virtual bool isNot() const;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
 
         private:
             OperatorType operatorType;

src/storm/logic/UnaryBooleanStateFormula.cpp

@@ -27,12 +27,17 @@ namespace storm {
             return this->getOperator() == OperatorType::Not;
         }
                 
-        std::ostream& UnaryBooleanStateFormula::writeToStream(std::ostream& out) const {
+        std::ostream& UnaryBooleanStateFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
+            if (allowParentheses) {
+                out << "(";
+            }
             switch (operatorType) {
-                case OperatorType::Not: out << "!("; break;
+                case OperatorType::Not: out << "!"; break;
+            }
+            this->getSubformula().writeToStream(out, !this->getSubformula().isUnaryFormula());
+            if (allowParentheses) {
+                out << ")";
             }
-            this->getSubformula().writeToStream(out);
-            out << ")";
             return out;
         }
     }

src/storm/logic/UnaryBooleanStateFormula.h

@@ -24,7 +24,7 @@ namespace storm {
             
             virtual bool isNot() const;
             
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
 
         private:
             OperatorType operatorType;

src/storm/logic/UntilFormula.cpp

@@ -20,10 +20,16 @@ namespace storm {
             return visitor.visit(*this, data);
         }
         
-        std::ostream& UntilFormula::writeToStream(std::ostream& out) const {
+        std::ostream& UntilFormula::writeToStream(std::ostream& out, bool allowParentheses) const {
-            this->getLeftSubformula().writeToStream(out);
+            if (allowParentheses) {
+                out << "(";
+            }
+            this->getLeftSubformula().writeToStream(out, true);
             out << " U ";
-            this->getRightSubformula().writeToStream(out);
+            this->getRightSubformula().writeToStream(out, true);
+            if (allowParentheses) {
+                out << ")";
+            }
             return out;
         }
     }

src/storm/logic/UntilFormula.h

@@ -18,7 +18,7 @@ namespace storm {
 
             virtual boost::any accept(FormulaVisitor const& visitor, boost::any const& data) const override;
                         
-            virtual std::ostream& writeToStream(std::ostream& out) const override;
+            virtual std::ostream& writeToStream(std::ostream& out, bool allowParentheses = false) const override;
         };
     }
 }