Add cross join support for Hql and Linq query provider

Author: maca88

src/NHibernate.Test/Async/Hql/EntityJoinHqlTest.cs

@@ -274,6 +274,27 @@ public async Task EntityJoinWithFetchesAsync()
 			}
 		}
 
+		[Test]
+		public async Task CrossJoinAndWhereClauseAsync()
+		{
+			using (var sqlLog = new SqlLogSpy())
+			using (var session = OpenSession())
+			{
+				var result = await (session.CreateQuery(
+					"SELECT s " +
+					"FROM EntityComplex s cross join EntityComplex q " +
+					"where s.SameTypeChild.Id = q.SameTypeChild.Id"
+				).ListAsync());
+
+				Assert.That(result, Has.Count.EqualTo(1));
+				Assert.That(sqlLog.Appender.GetEvents().Length, Is.EqualTo(1), "Only one SQL select is expected");
+				if (Dialect.SupportsCrossJoin)
+				{
+					Assert.That(sqlLog.GetWholeLog(), Does.Contain("cross join"), "A cross join is expected in the SQL select");
+				}
+			}
+		}
+
 		#region Test Setup
 
 		protected override HbmMapping GetMappings()

src/NHibernate.Test/Async/Linq/ByMethod/JoinTests.cs

@@ -31,5 +31,31 @@ public async Task MultipleLinqJoinsWithSameProjectionNamesAsync()
 			Assert.That(orders.Count, Is.EqualTo(828));
 			Assert.IsTrue(orders.All(x => x.FirstId == x.SecondId - 1 && x.SecondId == x.ThirdId - 1));
 		}
+
+		[Test]
+		public async Task CrossJoinWithPredicateInOnStatementAsync()
+		{
+			var result =
+				await ((from o in db.Orders
+				from p in db.Products
+				join d in db.OrderLines
+					on new { o.OrderId, p.ProductId } equals new { d.Order.OrderId, d.Product.ProductId }
+					into details
+				from d in details
+				select new { o.OrderId, p.ProductId, d.UnitPrice }).Take(10).ToListAsync());
+
+			Assert.That(result.Count, Is.EqualTo(10));
+		}
+
+		[Test]
+		public async Task CrossJoinWithPredicateInWhereStatementAsync()
+		{
+			var result = await ((from o in db.Orders
+						from o2 in db.Orders.Where(x => x.Freight > 50)
+						where (o.OrderId == o2.OrderId + 1) || (o.OrderId == o2.OrderId - 1)
+						select new { o.OrderId, OrderId2 = o2.OrderId }).ToListAsync());
+
+			Assert.That(result.Count, Is.EqualTo(720));
+		}
 	}
 }

src/NHibernate.Test/Hql/EntityJoinHqlTest.cs

@@ -264,7 +264,7 @@ public void EntityJoinWithFetches()
 		}
 
 		[Test, Ignore("Failing for unrelated reasons")]
-		public void CrossJoinAndWithClause()
+		public void ImplicitJoinAndWithClause()
 		{
 			//This is about complex theta style join fix that was implemented in hibernate along with entity join functionality
 			//https://hibernate.atlassian.net/browse/HHH-7321
@@ -279,6 +279,27 @@ public void CrossJoinAndWithClause()
 			}
 		}
 
+		[Test]
+		public void CrossJoinAndWhereClause()
+		{
+			using (var sqlLog = new SqlLogSpy())
+			using (var session = OpenSession())
+			{
+				var result = session.CreateQuery(
+					"SELECT s " +
+					"FROM EntityComplex s cross join EntityComplex q " +
+					"where s.SameTypeChild.Id = q.SameTypeChild.Id"
+				).List();
+
+				Assert.That(result, Has.Count.EqualTo(1));
+				Assert.That(sqlLog.Appender.GetEvents().Length, Is.EqualTo(1), "Only one SQL select is expected");
+				if (Dialect.SupportsCrossJoin)
+				{
+					Assert.That(sqlLog.GetWholeLog(), Does.Contain("cross join"), "A cross join is expected in the SQL select");
+				}
+			}
+		}
+
 		#region Test Setup
 
 		protected override HbmMapping GetMappings()

src/NHibernate.Test/Linq/ByMethod/JoinTests.cs

@@ -19,5 +19,31 @@ public void MultipleLinqJoinsWithSameProjectionNames()
 			Assert.That(orders.Count, Is.EqualTo(828));
 			Assert.IsTrue(orders.All(x => x.FirstId == x.SecondId - 1 && x.SecondId == x.ThirdId - 1));
 		}
+
+		[Test]
+		public void CrossJoinWithPredicateInOnStatement()
+		{
+			var result =
+				(from o in db.Orders
+				from p in db.Products
+				join d in db.OrderLines
+					on new { o.OrderId, p.ProductId } equals new { d.Order.OrderId, d.Product.ProductId }
+					into details
+				from d in details
+				select new { o.OrderId, p.ProductId, d.UnitPrice }).Take(10).ToList();
+
+			Assert.That(result.Count, Is.EqualTo(10));
+		}
+
+		[Test]
+		public void CrossJoinWithPredicateInWhereStatement()
+		{
+			var result = (from o in db.Orders
+						from o2 in db.Orders.Where(x => x.Freight > 50)
+						where (o.OrderId == o2.OrderId + 1) || (o.OrderId == o2.OrderId - 1)
+						select new { o.OrderId, OrderId2 = o2.OrderId }).ToList();
+
+			Assert.That(result.Count, Is.EqualTo(720));
+		}
 	}
 }

src/NHibernate/AdoNet/Util/BasicFormatter.cs

@@ -20,6 +20,7 @@ static BasicFormatter()
 		{
 			beginClauses.Add("left");
 			beginClauses.Add("right");
+			beginClauses.Add("cross");
 			beginClauses.Add("inner");
 			beginClauses.Add("outer");
 			beginClauses.Add("group");

src/NHibernate/Dialect/DB2Dialect.cs

@@ -300,6 +300,9 @@ public override string ForUpdateString
 
 		public override bool SupportsResultSetPositionQueryMethodsOnForwardOnlyCursor => false;
 
+		/// <inheritdoc />
+		public override bool SupportsCrossJoin => false; // DB2 v9.1 doesn't support 'cross join' syntax
+
 		public override bool SupportsLobValueChangePropogation => false;
 
 		public override bool SupportsExistsInSelect => false;

src/NHibernate/Dialect/Dialect.cs

@@ -1337,6 +1337,11 @@ public virtual JoinFragment CreateOuterJoinFragment()
 			return new ANSIJoinFragment();
 		}
 
+		/// <summary>
+		/// Does this dialect support CROSS JOIN?
+		/// </summary>
+		public virtual bool SupportsCrossJoin => true;
+
 		/// <summary> 
 		/// Create a <see cref="CaseFragment"/> strategy responsible
 		/// for handling this dialect's variations in how CASE statements are

src/NHibernate/Dialect/InformixDialect0940.cs

@@ -126,7 +126,10 @@ public override JoinFragment CreateOuterJoinFragment()
             return new ANSIJoinFragment();
         }
 
-        /// <summary>
+		/// <inheritdoc />
+		public override bool SupportsCrossJoin => false;
+
+		/// <summary>
         /// Does this Dialect have some kind of <c>LIMIT</c> syntax?
         /// </summary>
         /// <value>False, unless overridden.</value>

src/NHibernate/Dialect/Oracle10gDialect.cs

@@ -15,5 +15,8 @@ public override JoinFragment CreateOuterJoinFragment()
 		{
 			return new ANSIJoinFragment();
 		}
+
+		/// <inheritdoc />
+		public override bool SupportsCrossJoin => true;
 	}
 }

src/NHibernate/Dialect/Oracle8iDialect.cs

@@ -328,6 +328,9 @@ public override JoinFragment CreateOuterJoinFragment()
 			return new OracleJoinFragment();
 		}
 
+		/// <inheritdoc />
+		public override bool SupportsCrossJoin => false;
+
 		/// <summary> 
 		/// Map case support to the Oracle DECODE function.  Oracle did not
 		/// add support for CASE until 9i.