Add cross join support for Hql and Linq query provider

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. 

src/NHibernate/Dialect/SybaseASA9Dialect.cs

@@ -97,6 +97,9 @@ public override bool OffsetStartsAtOne
 			get { return true; }
 		}
 
+		/// <inheritdoc />
+		public override bool SupportsCrossJoin => false;
+
 		public override SqlString GetLimitString(SqlString queryString, SqlString offset, SqlString limit)
 		{
 			int intSelectInsertPoint = GetAfterSelectInsertPoint(queryString);

src/NHibernate/Dialect/SybaseASE15Dialect.cs

@@ -247,7 +247,10 @@ public override bool SupportsExpectedLobUsagePattern
 		{
 			get { return false; }
 		}
-
+
+		/// <inheritdoc />
+		public override bool SupportsCrossJoin => false;
+
 		public override char OpenQuote
 		{
 			get { return '['; }

src/NHibernate/Hql/Ast/ANTLR/Hql.g

@@ -19,6 +19,7 @@ tokens
 	BETWEEN='between';
 	CLASS='class';
 	COUNT='count';
+	CROSS='cross';
 	DELETE='delete';
 	DESCENDING='desc';
 	DOT;
@@ -255,6 +256,7 @@ fromClause
 fromJoin
 	: ( ( ( LEFT | RIGHT ) (OUTER)? ) | FULL | INNER )? JOIN^ (FETCH)? path (asAlias)? (propertyFetch)? (withClause)?
 	| ( ( ( LEFT | RIGHT ) (OUTER)? ) | FULL | INNER )? JOIN^ (FETCH)? ELEMENTS! OPEN! path CLOSE! (asAlias)? (propertyFetch)? (withClause)?
+	| CROSS JOIN^ { WeakKeywords(); } path (asAlias)?
 	;
 
 withClause

src/NHibernate/Hql/Ast/ANTLR/HqlSqlWalker.g

@@ -306,6 +306,9 @@ joinType returns [int j]
 	| INNER {
 		$j = INNER;
 	}
+	| CROSS {
+		$j = CROSS;
+	}
 	;
 
 // Matches a path and returns the normalized string for the path (usually

src/NHibernate/Hql/Ast/ANTLR/Util/JoinProcessor.cs

@@ -48,6 +48,8 @@ public static JoinType ToHibernateJoinType(int astJoinType)
 					return JoinType.RightOuterJoin;
 				case HqlSqlWalker.FULL:
 					return JoinType.FullJoin;
+				case HqlSqlWalker.CROSS:
+					return JoinType.CrossJoin;
 				default:
 					throw new AssertionFailure("undefined join type " + astJoinType);
 			}

src/NHibernate/Hql/Ast/HqlTreeBuilder.cs

@@ -483,6 +483,11 @@ public HqlLeftJoin LeftJoin(HqlExpression expression, HqlAlias @alias)
 			return new HqlLeftJoin(_factory, expression, @alias);
 		}
 
+		public HqlCrossJoin CrossJoin(HqlExpression expression, HqlAlias @alias)
+		{
+			return new HqlCrossJoin(_factory, expression, @alias);
+		}
+
 		public HqlFetchJoin FetchJoin(HqlExpression expression, HqlAlias @alias)
 		{
 			return new HqlFetchJoin(_factory, expression, @alias);

src/NHibernate/Hql/Ast/HqlTreeNode.cs

@@ -851,6 +851,13 @@ public class HqlLeftJoin : HqlTreeNode
 		}
 	}
 
+	public class HqlCrossJoin : HqlTreeNode
+	{
+		public HqlCrossJoin(IASTFactory factory, HqlExpression expression, HqlAlias @alias) : base(HqlSqlWalker.JOIN, "join", factory, new HqlCross(factory), expression, @alias)
+		{
+		}
+	}
+
 	public class HqlFetchJoin : HqlTreeNode
 	{
 		public HqlFetchJoin(IASTFactory factory, HqlExpression expression, HqlAlias @alias)
@@ -906,6 +913,14 @@ public HqlLeft(IASTFactory factory)
 		}
 	}
 
+	public class HqlCross : HqlTreeNode
+	{
+		public HqlCross(IASTFactory factory)
+			: base(HqlSqlWalker.CROSS, "cross", factory)
+		{
+		}
+	}
+
 	public class HqlAny : HqlBooleanExpression
 	{
 		public HqlAny(IASTFactory factory) : base(HqlSqlWalker.ANY, "any", factory)

src/NHibernate/Linq/Visitors/QueryModelVisitor.cs

@@ -315,22 +315,20 @@ public override void VisitMainFromClause(MainFromClause fromClause, QueryModel q
 		public override void VisitAdditionalFromClause(AdditionalFromClause fromClause, QueryModel queryModel, int index)
 		{
 			var querySourceName = VisitorParameters.QuerySourceNamer.GetName(fromClause);
-
+			var fromExpressionTree = HqlGeneratorExpressionVisitor.Visit(fromClause.FromExpression, VisitorParameters);
+			var alias = _hqlTree.TreeBuilder.Alias(querySourceName);
 			if (fromClause.FromExpression is MemberExpression)
 			{
 				// It's a join
-				_hqlTree.AddFromClause(
-					_hqlTree.TreeBuilder.Join(
-						HqlGeneratorExpressionVisitor.Visit(fromClause.FromExpression, VisitorParameters).AsExpression(),
-						_hqlTree.TreeBuilder.Alias(querySourceName)));
+				_hqlTree.AddFromClause(_hqlTree.TreeBuilder.Join(fromExpressionTree.AsExpression(), alias));
 			}
 			else
 			{
-				// TODO - exact same code as in MainFromClause; refactor this out
-				_hqlTree.AddFromClause(
-					_hqlTree.TreeBuilder.Range(
-						HqlGeneratorExpressionVisitor.Visit(fromClause.FromExpression, VisitorParameters),
-						_hqlTree.TreeBuilder.Alias(querySourceName)));
+				var join = VisitorParameters.SessionFactory.Dialect.SupportsCrossJoin
+					? _hqlTree.TreeBuilder.CrossJoin(fromExpressionTree.AsExpression(), alias)
+					: (HqlTreeNode) _hqlTree.TreeBuilder.Range(fromExpressionTree, alias);
+
+				_hqlTree.AddFromClause(join);
 			}
 
 			base.VisitAdditionalFromClause(fromClause, queryModel, index);

src/NHibernate/SqlCommand/ANSIJoinFragment.cs

@@ -33,12 +33,21 @@ public override void AddJoin(string tableName, string alias, string[] fkColumns,
 				case JoinType.FullJoin:
 					joinString = " full outer join ";
 					break;
+				case JoinType.CrossJoin:
+					joinString = " cross join ";
+					break;
 				default:
 					throw new AssertionFailure("undefined join type");
 			}
 
-			_fromFragment.Add(joinString + tableName + ' ' + alias + " on ");
+			_fromFragment.Add(joinString).Add(tableName).Add(" ").Add(alias).Add(" ");
+			if (joinType == JoinType.CrossJoin)
+			{
+				// Cross join does not have an 'on' statement
+				return;
+			}
 
+			_fromFragment.Add("on ");
 			if (fkColumns.Length == 0)
 			{
 				AddBareCondition(_fromFragment, on);

src/NHibernate/SqlCommand/JoinFragment.cs

@@ -10,7 +10,8 @@ public enum JoinType
 		InnerJoin = 0,
 		FullJoin = 4,
 		LeftOuterJoin = 1,
-		RightOuterJoin = 2
+		RightOuterJoin = 2,
+		CrossJoin = 8
 	}
 
 	/// <summary>