generalize default expressions for generic methods

dynamicexpresso · Jun 10, 2022 · 02362c7 · 02362c7
1 parent d9f27a3
commit 02362c7
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Showing 2 changed files with 53 additions and 16 deletions.
diff --git a/src/DynamicExpresso.Core/Parsing/Parser.cs b/src/DynamicExpresso.Core/Parsing/Parser.cs
@@ -2004,6 +2004,37 @@ private static MethodData[] FindBestMethod(IEnumerable<MethodData> methods, Expr
 			return applicable;
 		}
 
+		private static Type GetConcreteTypeForGenericMethod(Type type, List<Expression> promotedArgs, MethodData method)
+		{
+			if (type.IsGenericType)
+			{
+				//Generic<T> type
+				var genericArguments = type.GetGenericArguments();
+				var concreteTypeParameters = new Type[genericArguments.Length];
+
+				for (var i = 0; i < genericArguments.Length; i++)
+				{
+					concreteTypeParameters[i] = GetConcreteTypeForGenericMethod(genericArguments[i], promotedArgs,method);
+				}
+
+				return type.GetGenericTypeDefinition().MakeGenericType(concreteTypeParameters);
+			}
+			else if (type.ContainsGenericParameters)
+			{
+				//T case
+				//try finding an actual parameter for the generic
+				for (var i = 0; i < promotedArgs.Count; i++)
+				{
+					if (method.Parameters[i].ParameterType == type)
+					{						
+						return promotedArgs[i].Type;
+					}
+				}
+			}
+
+			return type;//already a concrete type
+		}
+
 		private static bool CheckIfMethodIsApplicableAndPrepareIt(MethodData method, Expression[] args)
 		{
 			if (method.Parameters.Count(y => !y.HasDefaultValue && !HasParamsArrayType(y)) > args.Length)
@@ -2112,25 +2143,11 @@ private static bool CheckIfMethodIsApplicableAndPrepareIt(MethodData method, Exp
 			{
 				if (x.HasDefaultValue)
 				{
-					var parameterType = x.ParameterType;
-					if (x.ParameterType.ContainsGenericParameters)
-					{
-						//try finding an actual parameter for the generic
-						for(var i = 0; i < promotedArgs.Count; i++)
-						{
-							var actualArg = promotedArgs[i];
-							if (method.Parameters[i].ParameterType == x.ParameterType)
-							{
-								parameterType = actualArg.Type;
-								break;
-							}
-						}
-					}
-
+					var parameterType = GetConcreteTypeForGenericMethod(x.ParameterType, promotedArgs, method);
 
 					return Expression.Constant(x.DefaultValue, parameterType);
 				}
-					
+
 
 				if (HasParamsArrayType(x))
 				{

diff --git a/test/DynamicExpresso.UnitTest/MemberInvocationTest.cs b/test/DynamicExpresso.UnitTest/MemberInvocationTest.cs
@@ -325,6 +325,11 @@ public void Method_with_generic_param()
 
 			Assert.AreEqual(x.MethodWithGenericParamAndDefault(y,y), target.Eval("x.MethodWithGenericParamAndDefault(y,y)", parameters));
 			Assert.AreEqual(x.MethodWithGenericParamAndDefault(y), target.Eval("x.MethodWithGenericParamAndDefault(y)", parameters));
+			Assert.AreEqual(x.MethodWithGenericParamAndDefault1Levels(y), target.Eval("x.MethodWithGenericParamAndDefault1Levels(y)", parameters));
+			Assert.AreEqual(x.MethodWithGenericParamAndDefault2Levels(y), target.Eval("x.MethodWithGenericParamAndDefault2Levels(y)", parameters));
+			Assert.AreEqual(x.MethodWithGenericParamAndDefault2Levels(y, w), target.Eval("x.MethodWithGenericParamAndDefault2Levels(y, w)", parameters));
+
+
 		}
 
 		[Test]
@@ -567,6 +572,21 @@ public T MethodWithGenericParamAndDefault<T>(T a, T b = default)
 				return a;
 			}
 
+			public T MethodWithGenericParamAndDefault1Levels<T>(T a, List<T> b = default)
+			{
+				return a;
+			}
+
+			public T MethodWithGenericParamAndDefault2Levels<T>(T a, List<List<T>> b = default)
+			{
+				return a;
+			}
+
+			public T MethodWithGenericParamAndDefault2Levels<T, T2>(T a, T2 b, List<T> c = default, List<List<T2>> d = default)
+			{
+				return a;
+			}
+
 			public string MethodWithOptionalParam(string param1, string param2 = "2", string param3 = "3")
 			{
 				return string.Format("{0} {1} {2}", param1, param2, param3);