support for generic (static) methods, thus also support for extension… (#517)

* support for generic (static) methods, thus also support for extension methods
(related to #386 )

* support for generic (static) methods, thus also support for extension methods
(related to #386 )

Author: dogguts

src/System.Linq.Dynamic.Core/Parser/ExpressionParser.cs

@@ -1695,9 +1695,12 @@ Expression ParseMemberAccess(Type type, Expression expression)
                             throw ParseError(errorPos, Res.MethodsAreInaccessible, TypeHelper.GetTypeName(method.DeclaringType));
                         }
 
-                        if (expression == null)
+                        if (method.IsGenericMethod)
                         {
-                            return Expression.Call(null, method, args);
+                            var genericParameters = method.GetParameters().Where(p => p.ParameterType.IsGenericParameter);
+                            var typeArguments = genericParameters.Select(a => args[a.Position].Type);
+                            var constructedMethod = method.MakeGenericMethod(typeArguments.ToArray());
+                            return Expression.Call(expression, constructedMethod, args);
                         }
                         else
                         {

src/System.Linq.Dynamic.Core/Parser/ExpressionPromoter.cs

@@ -22,7 +22,7 @@ public ExpressionPromoter(ParsingConfig config)
         /// <inheritdoc cref="IExpressionPromoter.Promote(Expression, Type, bool, bool)"/>
         public virtual Expression Promote(Expression expr, Type type, bool exact, bool convertExpr)
         {
-            if (expr.Type == type)
+            if (expr.Type == type || type.IsGenericParameter)
             {
                 return expr;
             }

src/System.Linq.Dynamic.Core/Parser/SupportedMethods/MethodFinder.cs

@@ -58,7 +58,7 @@ public int FindMethod(Type type, string methodName, bool staticAccess, ref Expre
                 {
                     if (_parsingConfig.CustomTypeProvider.GetExtensionMethods().TryGetValue(t, out var extensionMethodsOfType))
                     {
-                        methods.AddRange(extensionMethodsOfType.Where(m => m.Name.Equals(methodName, StringComparison.OrdinalIgnoreCase) && !m.IsGenericMethod));
+                        methods.AddRange(extensionMethodsOfType.Where(m => m.Name.Equals(methodName, StringComparison.OrdinalIgnoreCase)));
                     }
                 }
 

test/System.Linq.Dynamic.Core.Tests/DynamicExpressionParserTests.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Globalization;
 using System.Linq.Dynamic.Core.CustomTypeProviders;
 using System.Linq.Dynamic.Core.Exceptions;
@@ -1354,5 +1354,36 @@ public void DynamicExpressionParser_ParseLambda_String_TrimEnd_1_Parameter()
             // Assert
             result.Should().BeTrue();
         }
+
+        public class DefaultDynamicLinqCustomTypeProviderForGenericExtensionMethod : CustomTypeProviders.DefaultDynamicLinqCustomTypeProvider
+        {
+            public override HashSet<Type> GetCustomTypes() => new HashSet<Type>(base.GetCustomTypes()) { typeof(Methods), typeof(MethodsItemExtension) };
+        }
+
+        [Fact]
+        public void DynamicExpressionParser_ParseLambda_GenericExtensionMethod()
+        {
+            // Arrange
+            var testList = User.GenerateSampleModels(51);
+            var config = new ParsingConfig()
+            {
+                CustomTypeProvider = new DefaultDynamicLinqCustomTypeProviderForGenericExtensionMethod()
+            };
+
+            // Act
+            string query = "x => MethodsItemExtension.Functions.EfCoreCollate(x.UserName, \"tlh-KX\")==\"User4\" || MethodsItemExtension.Functions.EfCoreCollate(x.UserName, \"tlh-KX\")==\"User2\"";
+            var expression = DynamicExpressionParser.ParseLambda<User, bool>(config, false, query);
+            var del = expression.Compile();
+
+            var result = Enumerable.Where(testList, del);
+
+
+            var expected = testList.Where(x => new string[] { "User4", "User2" }.Contains(x.UserName)).ToList();
+
+            // Assert
+            Check.That(result).IsNotNull();
+            Check.That(result).HasSize(expected.Count);
+            Check.That(result).Equals(expected);
+        }
     }
 }

test/System.Linq.Dynamic.Core.Tests/ExpressionTests.cs

@@ -1,4 +1,4 @@
-using System.Collections.Generic;
+using System.Collections.Generic;
 using System.Dynamic;
 using System.Globalization;
 using System.Linq.Dynamic.Core.Exceptions;
@@ -1304,6 +1304,69 @@ public void ExpressionTests_Method_OneParam_With_it()
             Assert.Equal(expected.Count(), result.Count());
         }
 
+        public class DefaultDynamicLinqCustomTypeProviderForStaticTesting : CustomTypeProviders.DefaultDynamicLinqCustomTypeProvider
+        {
+            public override HashSet<Type> GetCustomTypes() => new HashSet<Type>(base.GetCustomTypes()) { typeof(Methods), typeof(MethodsItemExtension) };
+        }
+
+        [Fact]
+        public void ExpressionTests_MethodCall_GenericStatic()
+        {
+            var config = new ParsingConfig
+            {
+                CustomTypeProvider = new DefaultDynamicLinqCustomTypeProviderForStaticTesting()
+            };
+
+            // Arrange
+            var list = new[] { 0, 1, 2, 3, 4 }.Select(value => new Methods.Item { Value = value }).ToArray();
+
+            // Act
+            var expectedResult = list.Where(x => Methods.StaticGenericMethod(x));
+            var result = list.AsQueryable().Where(config, "Methods.StaticGenericMethod(it)");
+
+            // Assert
+            Assert.Equal(expectedResult.Count(), result.Count());
+        }
+
+        [Fact]
+        public void ExpressionTests_MethodCall_Generic()
+        {
+            var config = new ParsingConfig
+            {
+                CustomTypeProvider = new DefaultDynamicLinqCustomTypeProviderForStaticTesting()
+            };
+
+            // Arrange
+            var list = new[] { 0, 1, 2, 3, 4 }.Select(value => new Methods.Item { Value = value }).ToArray();
+
+            // Act
+            var methods = new Methods();
+            var expectedResult = list.Where(x => methods.GenericMethod(x));
+            var result = list.AsQueryable().Where("@0.GenericMethod(it)", methods);
+
+            // Assert
+            Assert.Equal(expectedResult.Count(), result.Count());
+        }
+
+        [Fact]
+        public void ExpressionTests_MethodCall_GenericExtension()
+        {
+            var config = new ParsingConfig
+            {
+                CustomTypeProvider = new DefaultDynamicLinqCustomTypeProviderForStaticTesting()
+            };
+
+            // Arrange
+            var list = new[] { 0, 1, 2, 3, 4 }.Select(value => new Methods.Item { Value = value }).ToArray();
+
+            // Act
+            var methods = new Methods();
+            var expectedResult = list.Where(x => MethodsItemExtension.Functions.EfCoreCollate(x.Value, "tlh-KX") == 2);
+            var result = list.AsQueryable().Where(config, "MethodsItemExtension.Functions.EfCoreCollate(it.Value,\"tlh-KX\")==2");
+
+            // Assert
+            Assert.Equal(expectedResult.Count(), result.Count());
+        }
 
         [Fact]
         public void ExpressionTests_MethodCall_ValueTypeToValueTypeParameter()

test/System.Linq.Dynamic.Core.Tests/Helpers/Models/Methods.cs

@@ -1,4 +1,4 @@
-namespace System.Linq.Dynamic.Core.Tests.Helpers.Models
+namespace System.Linq.Dynamic.Core.Tests.Helpers.Models
 {
     public class Methods
     {
@@ -22,5 +22,17 @@ public class Item
         {
             public int Value { get; set; }
         }
+
+        public static bool StaticGenericMethod<T>(T value) => value is Item item && item.Value == 1;
+        public bool GenericMethod<T>(T value) => value is Item item && item.Value == 1;
+
+    }
+
+    public static class MethodsItemExtension
+    {
+        public class DummyFunctions { }
+        public static DummyFunctions Functions => new DummyFunctions();
+
+        public static T EfCoreCollate<T>(this DummyFunctions _, T value, string collation) => value;
     }
 }