move enum equals implementation to IExpressionTransformer because special expression expression behavior

Author: Tomas Lukac

src/NHibernate.Test/Linq/FunctionTests.cs

@@ -36,8 +36,8 @@ public void LikeFunctionWithEscapeCharacter()
 				session.Flush();
 
 				var query = (from e in db.Employees
-				             where NHibernate.Linq.SqlMethods.Like(e.FirstName, employeeNameEscaped, escapeChar)
-				             select e).ToList();
+							 where NHibernate.Linq.SqlMethods.Like(e.FirstName, employeeNameEscaped, escapeChar)
+							 select e).ToList();
 
 				Assert.That(query.Count, Is.EqualTo(1));
 				Assert.That(query[0].FirstName, Is.EqualTo(employeeName));
@@ -81,8 +81,8 @@ where NHibernate.Test.Linq.FunctionTests.SqlMethods.Like(e.FirstName, "Ma%et")
 		public void SubstringFunction2()
 		{
 			var query = (from e in db.Employees
-				where e.FirstName.Substring(0, 2) == "An"
-				select e).ToList();
+						 where e.FirstName.Substring(0, 2) == "An"
+						 select e).ToList();
 
 			Assert.That(query.Count, Is.EqualTo(2));
 		}
@@ -91,8 +91,8 @@ where e.FirstName.Substring(0, 2) == "An"
 		public void SubstringFunction1()
 		{
 			var query = (from e in db.Employees
-				where e.FirstName.Substring(3) == "rew"
-				select e).ToList();
+						 where e.FirstName.Substring(3) == "rew"
+						 select e).ToList();
 
 			Assert.That(query.Count, Is.EqualTo(1));
 			Assert.That(query[0].FirstName, Is.EqualTo("Andrew"));
@@ -130,21 +130,21 @@ public void ReplaceFunction()
 			var query = from e in db.Employees
 						where e.FirstName.StartsWith("An")
 						select new
-							{
-								Before = e.FirstName,
-								// This one call the standard string.Replace, not the extension. The linq registry handles it.
-								AfterMethod = e.FirstName.Replace("An", "Zan"),
-								AfterExtension = ExtensionMethods.Replace(e.FirstName, "An", "Zan"),
-								AfterNamedExtension = e.FirstName.ReplaceExtension("An", "Zan"),
-								AfterEvaluableExtension = e.FirstName.ReplaceWithEvaluation("An", "Zan"),
-								AfterEvaluable2Extension = e.FirstName.ReplaceWithEvaluation2("An", "Zan"),
+						{
+							Before = e.FirstName,
+							// This one call the standard string.Replace, not the extension. The linq registry handles it.
+							AfterMethod = e.FirstName.Replace("An", "Zan"),
+							AfterExtension = ExtensionMethods.Replace(e.FirstName, "An", "Zan"),
+							AfterNamedExtension = e.FirstName.ReplaceExtension("An", "Zan"),
+							AfterEvaluableExtension = e.FirstName.ReplaceWithEvaluation("An", "Zan"),
+							AfterEvaluable2Extension = e.FirstName.ReplaceWithEvaluation2("An", "Zan"),
 							BeforeConst = suppliedName,
-								// This one call the standard string.Replace, not the extension. The linq registry handles it.
-								AfterMethodConst = suppliedName.Replace("An", "Zan"),
-								AfterExtensionConst = ExtensionMethods.Replace(suppliedName, "An", "Zan"),
-								AfterNamedExtensionConst = suppliedName.ReplaceExtension("An", "Zan"),
-								AfterEvaluableExtensionConst = suppliedName.ReplaceWithEvaluation("An", "Zan"),
-								AfterEvaluable2ExtensionConst = suppliedName.ReplaceWithEvaluation2("An", "Zan")
+							// This one call the standard string.Replace, not the extension. The linq registry handles it.
+							AfterMethodConst = suppliedName.Replace("An", "Zan"),
+							AfterExtensionConst = ExtensionMethods.Replace(suppliedName, "An", "Zan"),
+							AfterNamedExtensionConst = suppliedName.ReplaceExtension("An", "Zan"),
+							AfterEvaluableExtensionConst = suppliedName.ReplaceWithEvaluation("An", "Zan"),
+							AfterEvaluable2ExtensionConst = suppliedName.ReplaceWithEvaluation2("An", "Zan")
 						};
 			var results = query.ToList();
 			var s = ObjectDumper.Write(results);
@@ -171,12 +171,12 @@ where e.FirstName.StartsWith("An")
 			// Should cause ReplaceWithEvaluation to fail
 			suppliedName = null;
 			var failingQuery = from e in db.Employees
-						where e.FirstName.StartsWith("An")
-						select new
-						{
-							Before = e.FirstName,
-							AfterEvaluableExtensionConst = suppliedName.ReplaceWithEvaluation("An", "Zan")
-						};
+							   where e.FirstName.StartsWith("An")
+							   select new
+							   {
+								   Before = e.FirstName,
+								   AfterEvaluableExtensionConst = suppliedName.ReplaceWithEvaluation("An", "Zan")
+							   };
 			Assert.That(() => failingQuery.ToList(), Throws.InstanceOf<HibernateException>().And.InnerException.InstanceOf<ArgumentNullException>());
 		}
 
@@ -248,7 +248,7 @@ where lowerName.Contains("a")
 		public void TwoFunctionExpression()
 		{
 			var query = from e in db.Employees
-						where e.FirstName.IndexOf("A") == e.BirthDate.Value.Month 
+						where e.FirstName.IndexOf("A") == e.BirthDate.Value.Month
 						select e.FirstName;
 
 			ObjectDumper.Write(query);
@@ -285,9 +285,9 @@ public void Trim()
 		{
 			using (session.BeginTransaction())
 			{
-				AnotherEntity ae1 = new AnotherEntity {Input = " hi "};
-				AnotherEntity ae2 = new AnotherEntity {Input = "hi"};
-				AnotherEntity ae3 = new AnotherEntity {Input = "heh"};
+				AnotherEntity ae1 = new AnotherEntity { Input = " hi " };
+				AnotherEntity ae2 = new AnotherEntity { Input = "hi" };
+				AnotherEntity ae3 = new AnotherEntity { Input = "heh" };
 				session.Save(ae1);
 				session.Save(ae2);
 				session.Save(ae3);
@@ -303,7 +303,7 @@ public void Trim()
 
 				// Check when passed as array
 				// (the single character parameter is a new overload in .netcoreapp2.0, but not net461 or .netstandard2.0).
-				Assert.AreEqual(1, session.Query<AnotherEntity>().Count(e => e.Input.Trim(new [] { 'h' }) == "e"));
+				Assert.AreEqual(1, session.Query<AnotherEntity>().Count(e => e.Input.Trim(new[] { 'h' }) == "e"));
 				Assert.AreEqual(1, session.Query<AnotherEntity>().Count(e => e.Input.TrimStart(new[] { 'h' }) == "eh"));
 				Assert.AreEqual(1, session.Query<AnotherEntity>().Count(e => e.Input.TrimEnd(new[] { 'h' }) == "he"));
 
@@ -316,9 +316,9 @@ public void TrimInitialWhitespace()
 		{
 			using (session.BeginTransaction())
 			{
-				session.Save(new AnotherEntity {Input = " hi"});
-				session.Save(new AnotherEntity {Input = "hi"});
-				session.Save(new AnotherEntity {Input = "heh"});
+				session.Save(new AnotherEntity { Input = " hi" });
+				session.Save(new AnotherEntity { Input = "hi" });
+				session.Save(new AnotherEntity { Input = "heh" });
 				session.Flush();
 
 				Assert.That(session.Query<AnotherEntity>().Count(e => e.Input.TrimStart() == "hi"), Is.EqualTo(2));
@@ -372,7 +372,7 @@ public void WhereBoolConstantEqual()
 			var query = from item in db.Role
 						where item.IsActive.Equals(true)
 						select item;
-			
+
 			ObjectDumper.Write(query);
 		}
 
@@ -382,7 +382,7 @@ public void WhereBoolConditionEquals()
 			var query = from item in db.Role
 						where item.IsActive.Equals(item.Name != null)
 						select item;
-			
+
 			ObjectDumper.Write(query);
 		}
 
@@ -392,7 +392,7 @@ public void WhereBoolParameterEqual()
 			var query = from item in db.Role
 						where item.IsActive.Equals(1 == 1)
 						select item;
-			
+
 			ObjectDumper.Write(query);
 		}
 
@@ -412,8 +412,8 @@ where item.IsActive.Equals(f())
 		public void WhereLongEqual()
 		{
 			var query = from item in db.PatientRecords
-						 where item.Id.Equals(-1)
-						 select item;
+						where item.Id.Equals(-1)
+						select item;
 
 			ObjectDumper.Write(query);
 		}
@@ -427,7 +427,7 @@ where item.RegisteredAt.Equals(DateTime.Today)
 
 			ObjectDumper.Write(query);
 		}
-		
+
 		[Test]
 		public void WhereGuidEqual()
 		{
@@ -436,7 +436,7 @@ where item.Reference.Equals(Guid.Empty)
 						select item;
 
 			ObjectDumper.Write(query);
-		}		
+		}
 
 		[Test]
 		public void WhereDoubleEqual()
@@ -446,8 +446,8 @@ where item.BodyWeight.Equals(-1)
 						select item;
 
 			ObjectDumper.Write(query);
-		}	
-	
+		}
+
 		[Test]
 		[Ignore("Not mapped entity")]
 		public void WhereFloatEqual()
@@ -457,7 +457,7 @@ where item.Float.Equals(-1)
 						select item;
 
 			ObjectDumper.Write(query);
-		}	
+		}
 
 		[Test]
 		[Ignore("Not mapped entity")]
@@ -499,14 +499,20 @@ where item.Gender.Equals(Gender.Female)
 						select item;
 
 			ObjectDumper.Write(query);
+
+			query = from item in db.PatientRecords
+					where item.Gender.Equals(item.Gender)
+					select item;
+
+			ObjectDumper.Write(query);
 		}
 
 		[Test]
 		public void WhereEquatableEqual()
 		{
 			var query = from item in db.Shippers
-			            where ((IEquatable<Guid>) item.Reference).Equals(Guid.Empty)
-			            select item;
+						where ((IEquatable<Guid>) item.Reference).Equals(Guid.Empty)
+						select item;
 
 			ObjectDumper.Write(query);
 		}

src/NHibernate/Linq/ExpressionTransformers/EnumEqualsTransformer.cs

@@ -0,0 +1,50 @@
+using System;
+using System.Linq.Expressions;
+using Remotion.Linq.Parsing.ExpressionVisitors.Transformation;
+
+namespace NHibernate.Linq.ExpressionTransformers
+{
+	/// <summary>
+	/// Transforms <see cref="Enum"/>.Equals method to equality operator.
+	/// This cannot be done easily in <see cref="Functions.IHqlGeneratorForMethod"/> as Equals operator
+	/// is boxed to ((object)Enum).Equals((object)EnumValue) expression.
+	/// </summary>
+	public class EnumEqualsTransformer : IExpressionTransformer<MethodCallExpression>
+	{
+		public ExpressionType[] SupportedExpressionTypes => _supportedExpressionTypes;
+
+		private static readonly ExpressionType[] _supportedExpressionTypes = new[]
+		{
+			ExpressionType.Call
+		};
+
+		public Expression Transform(MethodCallExpression expression)
+		{
+			if (expression.Object?.Type.IsEnum == true &&
+				expression.Method.Name == nameof(Enum.Equals) &&
+				expression.Arguments.Count == 1)
+			{
+				return Expression.Equal(expression.Object, Unwrap(expression.Arguments[0], expression.Object.Type));
+			}
+
+			return expression;
+		}
+
+		private Expression Unwrap(Expression expression, System.Type type)
+		{
+			// 1) unwrap convert operand as convert is converting from enum type to object
+			if (expression is UnaryExpression u && u.NodeType == ExpressionType.Convert)
+			{
+				return u.Operand;
+			}
+
+			// 2) convert constant expression which is of type object
+			if (expression is ConstantExpression c)
+			{
+				return Expression.Convert(c, type);
+			}
+
+			return expression;
+		}
+	}
+}

src/NHibernate/Linq/Functions/DefaultLinqToHqlGeneratorsRegistry.cs

@@ -39,7 +39,6 @@ public DefaultLinqToHqlGeneratorsRegistry()
 			this.Merge(new EndsWithGenerator());
 			this.Merge(new ContainsGenerator());
 			this.Merge(new EqualsGenerator());
-			this.Merge(new EnumEqualsGenerator());
 			this.Merge(new ToUpperGenerator());
 			this.Merge(new ToLowerGenerator());
 			this.Merge(new SubStringGenerator());

src/NHibernate/Linq/Functions/EnumEqualsGenerator.cs

@@ -4,10 +4,8 @@
 using System.Linq;
 using System.Linq.Expressions;
 using System.Reflection;
-using NHibernate.Engine;
 using NHibernate.Linq.ExpressionTransformers;
 using NHibernate.Linq.Visitors;
-using NHibernate.Param;
 using NHibernate.Util;
 using Remotion.Linq;
 using Remotion.Linq.EagerFetching.Parsing;
@@ -27,6 +25,7 @@ static NhRelinqQueryParser()
 			var transformerRegistry = ExpressionTransformerRegistry.CreateDefault();
 			transformerRegistry.Register(new RemoveRedundantCast());
 			transformerRegistry.Register(new SimplifyCompareTransformer());
+			transformerRegistry.Register(new EnumEqualsTransformer());
 
 			// If needing a compound processor for adding other processing, do not use
 			// ExpressionTreeParser.CreateDefaultProcessor(transformerRegistry), it would
@@ -114,14 +113,14 @@ public NHibernateNodeTypeProvider()
 				new[] { ReflectHelper.FastGetMethodDefinition(EagerFetchingExtensionMethods.ThenFetch, default(INhFetchRequest<object, object>), default(Expression<Func<object, object>>)) },
 				typeof(ThenFetchOneExpressionNode));
 			methodInfoRegistry.Register(
-				new[] { ReflectHelper.FastGetMethodDefinition( EagerFetchingExtensionMethods.ThenFetchMany, default(INhFetchRequest<object, object>), default(Expression<Func<object, IEnumerable<object>>>)) },
+				new[] { ReflectHelper.FastGetMethodDefinition(EagerFetchingExtensionMethods.ThenFetchMany, default(INhFetchRequest<object, object>), default(Expression<Func<object, IEnumerable<object>>>)) },
 				typeof(ThenFetchManyExpressionNode));
 			methodInfoRegistry.Register(
 				new[]
 				{
 					ReflectHelper.FastGetMethodDefinition(LinqExtensionMethods.WithLock, default(IQueryable<object>), default(LockMode)),
 					ReflectHelper.FastGetMethodDefinition(LinqExtensionMethods.WithLock, default(IEnumerable<object>), default(LockMode))
-				}, 
+				},
 				typeof(LockExpressionNode));
 
 			var nodeTypeProvider = ExpressionTreeParser.CreateDefaultNodeTypeProvider();