Disallow invalid ValueTuple types.

Author: Elad Zelingher

src/net45/WampSharp/Core/Utilities/ValueTuple/ValueTupleTypeExtensions.cs

@@ -40,56 +40,43 @@ public static int GetValueTupleLength(this Type type)
 
             Type genericTypeDefinition = type.GetGenericTypeDefinition();
 
-            if (genericTypeDefinition == typeof(ValueTuple<>))
+            if (!genericTypeDefinition.IsLongTuple())
             {
-                return 1;
+                return genericTypeDefinition.GetGenericArguments().Length;
             }
-            if (genericTypeDefinition == typeof(ValueTuple<,>))
-            {
-                return 2;
-            }
-            if (genericTypeDefinition == typeof(ValueTuple<,,>))
-            {
-                return 3;
-            }
-            if (genericTypeDefinition == typeof(ValueTuple<,,,>))
-            {
-                return 4;
-            }
-            if (genericTypeDefinition == typeof(ValueTuple<,,,,>))
-            {
-                return 5;
-            }
-            if (genericTypeDefinition == typeof(ValueTuple<,,,,,>))
-            {
-                return 6;
-            }
-            if (genericTypeDefinition == typeof(ValueTuple<,,,,,,>))
-            {
-                return 7;
-            }
-            if (genericTypeDefinition == typeof(ValueTuple<,,,,,,,>))
+            else
             {
                 Type last = type.GetGenericArguments().Last();
 
-                if (!last.IsValueTuple())
-                {
-                    return 8;
-                }
-                else
-                {
-                    return 7 + last.GetValueTupleLength();
-                }
+                return (genericTypeDefinition.GetGenericArguments().Length - 1) +
+                       last.GetValueTupleLength();
             }
-
-            return 0;
         }
 
         public static bool IsLongTuple(this Type tupleType)
         {
             return tupleType.IsGenericType() &&
-                   tupleType.GetGenericTypeDefinition() == typeof(ValueTuple<,,,,,,,>) &&
-                   tupleType.GetGenericArguments().Last().IsValueTuple();
+                   tupleType.GetGenericTypeDefinition() == typeof(ValueTuple<,,,,,,,>);
+        }
+
+        public static bool IsValidTupleType(this Type tupleType)
+        {
+            if (tupleType.IsValueTuple())
+            {
+                if (tupleType.IsLongTuple())
+                {
+                    Type rest = tupleType.GetGenericArguments().Last();
+
+                    if (!rest.IsValueTuple())
+                    {
+                        return false;
+                    }
+                }
+
+                return true;
+            }
+
+            return false;
         }
 
         public static IEnumerable<Type> GetValueTupleElementTypes(this Type tupleType)

src/net45/WampSharp/WAMP2/V2/Api/Rx/WampEventValueTupleConverter.cs

@@ -37,6 +37,11 @@ protected WampEventValueTupleConverter()
                 throw new ArgumentException("Expected TTuple to be a ValueTuple");
             }
 
+            if (!tupleType.IsValidTupleType())
+            {
+                throw new ArgumentException("TTuple is an invalid ValueTuple. Expected TRest to be a ValueTuple.");
+            }
+
             mArrayConverter = ValueTupleArrayConverter<TTuple>.Value;
 
             Type converterType = GetConverterType();

src/net45/WampSharp/WAMP2/V2/Rpc/Callee/Reflection/MethodInfoValidation.cs

@@ -14,11 +14,16 @@ public static void ValidateTupleReturnType(MethodInfo method)
         {
             if (method.ReturnsTuple())
             {
-                if (method.ReturnParameter.IsDefined(typeof(TupleElementNamesAttribute)))
+                Type returnType = method.ReturnType;
+                Type tupleType = TaskExtensions.UnwrapReturnType(returnType);
+
+                if (!tupleType.IsValidTupleType())
                 {
-                    Type returnType = method.ReturnType;
-                    Type tupleType = TaskExtensions.UnwrapReturnType(returnType);
+                    ThrowHelper.MethodReturnsInvalidValueTuple(method);
+                }
 
+                if (method.ReturnParameter.IsDefined(typeof(TupleElementNamesAttribute)))
+                {
                     int tupleLength = tupleType.GetValueTupleLength();
 
                     TupleElementNamesAttribute attribute = 
@@ -157,6 +162,14 @@ public static void TupleReturnTypeAndOutRefParametersHaveCommonNames(MethodInfo
                         method.Name, method.DeclaringType.FullName, 
                         string.Join(", ", intersection)));
             }
+
+            public static void MethodReturnsInvalidValueTuple(MethodInfo method)
+            {
+                throw new ArgumentException
+                    (String.Format(
+                        "Method {0} of type {1} returns an invalid ValueTuple. Expected TRest to be a ValueTuple.",
+                        method.Name, method.DeclaringType.FullName));
+            }
         }
     }
 }