DdPrismModelBuilder now errors in case it has a program with unbounded integer variables as input

resources/examples/testfiles/mdp/unbounded.nm

@@ -0,0 +1,8 @@
+mdp
+const int N;
+module main
+	x : int;
+	[] x<=0 -> (x'=x+1);
+	[] x>0 -> (x'=N*x);
+endmodule
+

src/storm/builder/DdPrismModelBuilder.cpp

@@ -541,7 +541,7 @@ namespace storm {
         
         template <storm::dd::DdType Type, typename ValueType>
         bool DdPrismModelBuilder<Type, ValueType>::canHandle(storm::prism::Program const& program) {
-            return program.getModelType() != storm::prism::Program::ModelType::PTA;
+            return !program.hasUnboundedVariables() && (program.getModelType() != storm::prism::Program::ModelType::PTA);
         }
         
         template <storm::dd::DdType Type, typename ValueType>
@@ -1311,6 +1311,7 @@ namespace storm {
                 stream << ".";
                 STORM_LOG_THROW(false, storm::exceptions::InvalidArgumentException, "Program still contains these undefined constants: " + stream.str());
             }
+            STORM_LOG_THROW(!program.hasUnboundedVariables(), storm::exceptions::InvalidArgumentException, "Program contains unbounded variables which is not supported by the DD engine.");
             
             STORM_LOG_TRACE("Building representation of program:" << std::endl << program << std::endl);
             

src/test/storm/builder/DdPrismModelBuilderTest.cpp

@@ -319,3 +319,14 @@ TEST(DdPrismModelBuilderTest_Cudd, Composition) {
     EXPECT_EQ(21ul, mdp->getNumberOfChoices());
 }
 
+TEST(UnboundedTest_Sylvan, Mdp) {
+    storm::storage::SymbolicModelDescription modelDescription = storm::parser::PrismParser::parse(STORM_TEST_RESOURCES_DIR "/mdp/unbounded.nm");
+    storm::prism::Program program = modelDescription.preprocess("N=1").asPrismProgram();
+    EXPECT_FALSE(storm::builder::DdPrismModelBuilder<storm::dd::DdType::Sylvan>().canHandle(program));
+}
+
+TEST(UnboundedTest_Cudd, Mdp) {
+    storm::storage::SymbolicModelDescription modelDescription = storm::parser::PrismParser::parse(STORM_TEST_RESOURCES_DIR "/mdp/unbounded.nm");
+    storm::prism::Program program = modelDescription.preprocess("N=1").asPrismProgram();
+    EXPECT_FALSE(storm::builder::DdPrismModelBuilder<storm::dd::DdType::CUDD>().canHandle(program));
+}