Add enum HasFlag method support #829

Author: Tomas Lukac

src/NHibernate.Test/NHSpecificTest/GH3365/Fixture.cs

@@ -0,0 +1,69 @@
+using System.Linq;
+using NUnit.Framework;
+
+namespace NHibernate.Test.NHSpecificTest.GH3365
+{
+	[TestFixture]
+	public class Fixture : BugTestCase
+	{
+		protected override void OnSetUp()
+		{
+			using (var session = OpenSession())
+			using (var transaction = session.BeginTransaction())
+			{
+
+				var e1 = new Parent { Type = TestEnum.A | TestEnum.C };
+				session.Save(e1);
+
+				var e2 = new Child { Type = TestEnum.D, Parent = e1 };
+				session.Save(e2);
+
+				var e3 = new Child { Type = TestEnum.C, Parent = e1 };
+				session.Save(e3);
+
+				session.Flush();
+				transaction.Commit();
+			}
+		}
+
+		[Test]
+		public void SelectClass()
+		{
+			using (var session = OpenSession())
+			using (session.BeginTransaction())
+			{
+				var resultFound = session.Query<Parent>().Where(x => x.Type.HasFlag(TestEnum.A)).FirstOrDefault();
+
+				var resultNotFound = session.Query<Parent>().Where(x => x.Type.HasFlag(TestEnum.D)).FirstOrDefault();
+
+				Assert.That(resultFound, Is.Not.Null);
+				Assert.That(resultNotFound, Is.Null);
+			}
+		}
+
+		[Test]
+		public void SelectChildClassContainedInParent()
+		{
+			using (var session = OpenSession())
+			using (session.BeginTransaction())
+			{
+				var result = session.Query<Child>().Where(x => x.Parent.Type.HasFlag(x.Type)).FirstOrDefault();
+
+				Assert.That(result, Is.Not.Null);
+			}
+		}
+
+		protected override void OnTearDown()
+		{
+			base.OnTearDown();
+			using (ISession session = this.OpenSession())
+			{
+				foreach (var entity in new[] { nameof(Child), nameof(Parent) })
+				{
+					session.Delete($"from {entity}");
+					session.Flush();
+				}
+			}
+		}
+	}
+}

src/NHibernate.Test/NHSpecificTest/GH3365/Mappings.hbm.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<hibernate-mapping xmlns="urn:nhibernate-mapping-2.2" assembly="NHibernate.Test" namespace="NHibernate.Test.NHSpecificTest.GH3365">
+  <class name="Parent" table="parent">
+    <id name="Id" generator="guid.comb" />
+    <property name="Type" type="NHibernate.Type.EnumType`1[[NHibernate.Test.NHSpecificTest.GH3365.TestEnum, NHibernate.Test]], NHibernate"/>
+    <bag name="Children" lazy="true">
+      <key column="ParentId" />
+      <one-to-many class="Child" />
+    </bag>
+  </class>
+
+  <class name="Child" table="Child">
+    <id name="Id" generator="guid.comb" />
+    <property name="Type" type="NHibernate.Type.EnumType`1[[NHibernate.Test.NHSpecificTest.GH3365.TestEnum, NHibernate.Test]], NHibernate"/>
+    <many-to-one name="Parent" column="ParentId" not-null="true" />
+  </class>
+</hibernate-mapping>

src/NHibernate.Test/NHSpecificTest/GH3365/Model.cs

@@ -0,0 +1,23 @@
+using System;
+using System.Collections.Generic;
+
+namespace NHibernate.Test.NHSpecificTest.GH3365
+{
+	public class Parent
+	{
+		public virtual Guid Id { get; set; }
+
+		public virtual TestEnum Type { get; set; }
+
+		public virtual IList<Child> Children { get; set; } = new List<Child>();
+	}
+
+	public class Child
+	{
+		public virtual Guid Id { get; set; }
+
+		public virtual TestEnum Type { get; set; }
+
+		public virtual Parent Parent { get; set; }
+	}
+}

src/NHibernate.Test/NHSpecificTest/GH3365/TestEnum.cs

@@ -0,0 +1,13 @@
+using System;
+
+namespace NHibernate.Test.NHSpecificTest.GH3365
+{
+	[Flags]
+	public enum TestEnum
+	{
+		A = 1 << 0,
+		B = 1 << 1,
+		C = 1 << 2,
+		D = 1 << 3
+	}
+}

src/NHibernate/Linq/ExpressionTransformers/RemoveRedundantCast.cs

@@ -1,12 +1,13 @@
+using System;
 using System.Linq.Expressions;
 using NHibernate.Util;
 using Remotion.Linq.Parsing.ExpressionVisitors.Transformation;
 
 namespace NHibernate.Linq.ExpressionTransformers
 {
 	/// <summary>
-	/// Remove redundant casts to the same type or to superclass (upcast) in <see cref="ExpressionType.Convert"/>, <see cref=" ExpressionType.ConvertChecked"/> 
-	/// and <see cref="ExpressionType.TypeAs"/> <see cref="UnaryExpression"/>s  
+	/// Remove redundant casts to the same type or to superclass (upcast) in <see cref="ExpressionType.Convert"/>, <see cref=" ExpressionType.ConvertChecked"/>
+	/// and <see cref="ExpressionType.TypeAs"/> <see cref="UnaryExpression"/>s
 	/// </summary>
 	public class RemoveRedundantCast : IExpressionTransformer<UnaryExpression>
 	{
@@ -20,6 +21,7 @@ public class RemoveRedundantCast : IExpressionTransformer<UnaryExpression>
 		public Expression Transform(UnaryExpression expression)
 		{
 			if (expression.Type != typeof(object) &&
+				expression.Type != typeof(Enum) &&
 				expression.Type.IsAssignableFrom(expression.Operand.Type) &&
 				expression.Method == null &&
 				!expression.IsLiftedToNull)
@@ -29,7 +31,7 @@ public Expression Transform(UnaryExpression expression)
 
 			// Reduce double casting (e.g. (long?)(long)3 => (long?)3)
 			if (expression.Operand.NodeType == ExpressionType.Convert &&
-			    expression.Type.UnwrapIfNullable() == expression.Operand.Type)
+				expression.Type.UnwrapIfNullable() == expression.Operand.Type)
 			{
 				return Expression.Convert(((UnaryExpression) expression.Operand).Operand, expression.Type);
 			}

src/NHibernate/Linq/Functions/DefaultLinqToHqlGeneratorsRegistry.cs

@@ -25,6 +25,7 @@ public DefaultLinqToHqlGeneratorsRegistry()
 			RegisterGenerator(new ToStringRuntimeMethodHqlGenerator());
 			RegisterGenerator(new LikeGenerator());
 			RegisterGenerator(new GetValueOrDefaultGenerator());
+			RegisterGenerator(new HasFlagGenerator());
 
 			RegisterGenerator(new CompareGenerator());
 			this.Merge(new CompareGenerator());

src/NHibernate/Linq/Functions/HasFlagGenerator.cs

@@ -0,0 +1,34 @@
+using System;
+using System.Collections.ObjectModel;
+using System.Linq.Expressions;
+using System.Reflection;
+using NHibernate.Hql.Ast;
+using NHibernate.Linq.Visitors;
+
+namespace NHibernate.Linq.Functions
+{
+	internal class HasFlagGenerator : BaseHqlGeneratorForMethod, IRuntimeMethodHqlGenerator
+	{
+		private const string _bitAndFunctionName = "band";
+
+		public bool SupportsMethod(MethodInfo method)
+		{
+			return method.Name == nameof(Enum.HasFlag) && method.DeclaringType == typeof(Enum);
+		}
+
+		public IHqlGeneratorForMethod GetMethodGenerator(MethodInfo method)
+		{
+			return this;
+		}
+
+		public override HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, ReadOnlyCollection<Expression> arguments, HqlTreeBuilder treeBuilder, IHqlExpressionVisitor visitor)
+		{
+			return treeBuilder.Equality(
+						treeBuilder.MethodCall(
+							_bitAndFunctionName,
+							 visitor.Visit(targetObject).AsExpression(),
+							 visitor.Visit(arguments[0]).AsExpression()),
+						visitor.Visit(arguments[0]).AsExpression());
+		}
+	}
+}