Added escape character support in SqlMethods.Like

Update by OB: There were many unrelated formatting changes. Remove most.

Author: gliljas

src/NHibernate.Test/Linq/FunctionTests.cs

@@ -23,6 +23,38 @@ where NHibernate.Linq.SqlMethods.Like(e.FirstName, "Ma%et")
 			Assert.That(query[0].FirstName, Is.EqualTo("Margaret"));
 		}
 
+		[Test]
+		public void LikeFunctionWithEscapeCharacter()
+		{
+			using (var tx = session.BeginTransaction())
+			{
+				var employeeName = "Mar%aret";
+				var escapeChar = '\\';
+				var employeeNameEscaped = employeeName.Replace("%", escapeChar + "%");
+
+				//This entity will be flushed to the db, but rolled back when the test completes
+
+				session.Save(new Employee { FirstName = employeeName, LastName = "LastName" });
+				session.Flush();
+
+
+				var query = (from e in db.Employees
+				             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));
+
+				Assert.Throws<ArgumentException>(() =>
+				{
+					(from e in db.Employees
+					 where NHibernate.Linq.SqlMethods.Like(e.FirstName, employeeNameEscaped, e.FirstName.First())
+					 select e).ToList();
+				});
+				tx.Rollback();
+			}
+		}
+
 		private static class SqlMethods
 		{
 			public static bool Like(string expression, string pattern)
@@ -362,4 +394,4 @@ where item.Discount.Equals(-1)
 			ObjectDumper.Write(query);
 		}
 	}
-}
+}

src/NHibernate/Hql/Ast/HqlTreeBuilder.cs

@@ -356,6 +356,11 @@ public HqlLike Like(HqlExpression lhs, HqlExpression rhs)
 			return new HqlLike(_factory, lhs, rhs);
 		}
 
+		public HqlLike Like(HqlExpression lhs, HqlExpression rhs, HqlConstant escapeCharacter)
+		{
+			return new HqlLike(_factory, lhs, rhs, escapeCharacter);
+		}
+
 		public HqlConcat Concat(params HqlExpression[] args)
 		{
 			return new HqlConcat(_factory, args);
@@ -466,4 +471,4 @@ public HqlTreeNode Indices(HqlExpression dictionary)
 			return new HqlIndices(_factory, dictionary);
 		}
 	}
-}
+}

src/NHibernate/Hql/Ast/HqlTreeNode.cs

@@ -22,7 +22,7 @@ protected HqlTreeNode(int type, string text, IASTFactory factory, IEnumerable<Hq
 			AddChildren(children);
 		}
 
-		protected HqlTreeNode(int type, string text, IASTFactory factory, params HqlTreeNode[] children) : this(type, text, factory, (IEnumerable<HqlTreeNode>) children)
+		protected HqlTreeNode(int type, string text, IASTFactory factory, params HqlTreeNode[] children) : this(type, text, factory, (IEnumerable<HqlTreeNode>)children)
 		{
 		}
 
@@ -92,7 +92,7 @@ internal IASTNode AstNode
 
 		internal void AddChild(HqlTreeNode child)
 		{
-			if (child is HqlExpressionSubTreeHolder) 
+			if (child is HqlExpressionSubTreeHolder)
 			{
 				AddChildren(child.Children);
 			}
@@ -116,7 +116,7 @@ public static HqlBooleanExpression AsBooleanExpression(this HqlTreeNode node)
 		{
 			if (node is HqlDot)
 			{
-				return new HqlBooleanDot(node.Factory, (HqlDot) node);
+				return new HqlBooleanDot(node.Factory, (HqlDot)node);
 			}
 
 			// TODO - nice error handling if cast fails
@@ -220,8 +220,8 @@ internal HqlIdent(IASTFactory factory, System.Type type)
 					}
 					if (type == typeof(DateTimeOffset))
 					{
-					    SetText("datetimeoffset");
-					    break;
+						SetText("datetimeoffset");
+						break;
 					}
 					throw new NotSupportedException(string.Format("Don't currently support idents of type {0}", type.Name));
 			}
@@ -373,7 +373,7 @@ public HqlSkip(IASTFactory factory, HqlExpression parameter)
 	public class HqlTake : HqlStatement
 	{
 		public HqlTake(IASTFactory factory, HqlExpression parameter)
-			: base(HqlSqlWalker.TAKE, "take", factory, parameter) {}
+			: base(HqlSqlWalker.TAKE, "take", factory, parameter) { }
 	}
 
 	public class HqlConstant : HqlExpression
@@ -690,7 +690,7 @@ public HqlMax(IASTFactory factory, HqlExpression expression)
 			: base(HqlSqlWalker.AGGREGATE, "max", factory, expression)
 		{
 		}
-}
+	}
 
 	public class HqlMin : HqlExpression
 	{
@@ -818,6 +818,19 @@ public HqlLike(IASTFactory factory, HqlExpression lhs, HqlExpression rhs)
 			: base(HqlSqlWalker.LIKE, "like", factory, lhs, rhs)
 		{
 		}
+
+		public HqlLike(IASTFactory factory, HqlExpression lhs, HqlExpression rhs, HqlConstant escapeCharacter)
+		: base(HqlSqlWalker.LIKE, "like", factory, lhs, rhs, new HqlEscape(factory, escapeCharacter))
+		{
+		}
+	}
+
+	public class HqlEscape : HqlStatement
+	{
+		public HqlEscape(IASTFactory factory, HqlConstant escapeCharacter)
+			: base(HqlSqlWalker.ESCAPE, "escape", factory, escapeCharacter)
+		{
+		}
 	}
 
 	public class HqlConcat : HqlExpression
@@ -899,4 +912,4 @@ public HqlInList(IASTFactory factory, HqlTreeNode source)
 		{
 		}
 	}
-}
+}

src/NHibernate/Linq/Functions/StringGenerator.cs

@@ -18,9 +18,22 @@ public IEnumerable<MethodInfo> SupportedMethods
 		public HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, ReadOnlyCollection<Expression> arguments,
 		                            HqlTreeBuilder treeBuilder, IHqlExpressionVisitor visitor)
 		{
-			return treeBuilder.Like(
-				visitor.Visit(arguments[0]).AsExpression(),
-				visitor.Visit(arguments[1]).AsExpression());
+			if (arguments.Count == 2)
+			{
+				return treeBuilder.Like(
+					visitor.Visit(arguments[0]).AsExpression(),
+					visitor.Visit(arguments[1]).AsExpression());
+			}
+			if (arguments[2].NodeType == ExpressionType.Constant)
+			{
+				var escapeCharExpression = (ConstantExpression)arguments[2];
+				return treeBuilder.Like(
+					visitor.Visit(arguments[0]).AsExpression(),
+					visitor.Visit(arguments[1]).AsExpression(),
+					treeBuilder.Constant(escapeCharExpression.Value));
+			}
+			throw new ArgumentException("The escape character must be specified as literal value or a string variable");
+
 		}
 
 		public bool SupportsMethod(MethodInfo method)
@@ -34,7 +47,7 @@ public bool SupportsMethod(MethodInfo method)
 			// to avoid referencing Linq2Sql or Linq2NHibernate, if they so wish.
 
 			return method != null && method.Name == "Like" &&
-			       method.GetParameters().Length == 2 &&
+			       (method.GetParameters().Length == 2 || method.GetParameters().Length == 3) &&
 			       method.DeclaringType != null &&
 			       method.DeclaringType.FullName.EndsWith("SqlMethods");
 		}
@@ -284,4 +297,4 @@ public HqlTreeNode BuildHql(MethodInfo method, Expression targetObject, ReadOnly
 			return treeBuilder.MethodCall("str", visitor.Visit(targetObject).AsExpression());
 		}
 	}
-}
+}

src/NHibernate/Linq/SqlMethods.cs

@@ -5,16 +5,29 @@ namespace NHibernate.Linq
 	public static class SqlMethods
 	{
 		/// <summary>
-		/// Use the SqlMethods.Like() method in a Linq2NHibernate expression to generate
+		/// Use this method in a Linq2NHibernate expression to generate
 		/// an SQL LIKE expression. (If you want to avoid depending on the NHibernate.Linq namespace,
 		/// you can define your own replica of this method. Any 2-argument method named Like in a class named SqlMethods
-		/// will be translated.) This method can only be used in Linq2NHibernate expression, and will throw
+		/// will be translated.) This method can only be used in Linq2NHibernate expressions, and will throw
 		/// if called directly.
 		/// </summary>
 		public static bool Like(this string matchExpression, string sqlLikePattern)
 		{
 			throw new NotSupportedException(
 				"The NHibernate.Linq.SqlMethods.Like(string, string) method can only be used in Linq2NHibernate expressions.");
 		}
+
+		/// <summary>
+		/// Use this method in a Linq2NHibernate expression to generate
+		/// an SQL LIKE expression with an escape character defined. (If you want to avoid depending on the NHibernate.Linq namespace,
+		/// you can define your own replica of this method. Any 3-argument method named Like in a class named SqlMethods
+		/// will be translated.) This method can only be used in Linq2NHibernate expressions, and will throw
+		/// if called directly.
+		/// </summary>
+		public static bool Like(this string matchExpression, string sqlLikePattern, char escapeCharacter)
+		{
+			throw new NotSupportedException(
+				"The NHibernate.Linq.SqlMethods.Like(string, string) method can only be used in Linq2NHibernate expressions.");
+		}
 	}
 }