Pre-transform like arguments so the db can reuse the query plan

Fixes nhibernate#725

Author: hazzik

.editorconfig

@@ -1,42 +1,45 @@
 root=true
 
 [*]
-insert_final_newline = true
+insert_final_newline=true
 
 [*.cs]
-indent_style = tab
-dotnet_sort_system_directives_first = true
-csharp_space_after_cast = true
-csharp_new_line_before_open_brace = all
-csharp_new_line_before_else = true
-csharp_new_line_before_catch = true
-csharp_new_line_before_finally = true
-csharp_new_line_before_members_in_object_initializers = true
-csharp_new_line_before_members_in_anonymous_types = true
-csharp_new_line_between_query_expression_clauses = true
+indent_style=tab
+dotnet_sort_system_directives_first=true
+csharp_space_after_cast=true
+csharp_new_line_before_open_brace=all
+csharp_new_line_before_else=true
+csharp_new_line_before_catch=true
+csharp_new_line_before_finally=true
+csharp_new_line_before_members_in_object_initializers=true
+csharp_new_line_before_members_in_anonymous_types=true
+csharp_new_line_between_query_expression_clauses=true
+
+# ReSharper properties
+resharper_space_within_single_line_array_initializer_braces=true
 
 [*.xsd]
-indent_style = tab
+indent_style=tab
 
 [*.json]
-indent_style = space
-indent_size = 2
+indent_style=space
+indent_size=2
 
 [*.xml]
-indent_style = space
-indent_size = 2
+indent_style=space
+indent_size=2
 
 [*.csproj]
-indent_style = space
-indent_size = 2
+indent_style=space
+indent_size=2
 
 [*.vbproj]
-indent_style = space
-indent_size = 2
+indent_style=space
+indent_size=2
 
 [*.cshtml]
-indent_style = space
-indent_size = 4
+indent_style=space
+indent_size=4
 
 [*.g]
-indent_style = tab
+indent_style=tab

src/NHibernate/Linq/ExpressionTransformers/LikeTransformer.cs

@@ -0,0 +1,60 @@
+using System.Linq.Expressions;
+using System.Reflection;
+using NHibernate.Util;
+using Remotion.Linq.Parsing.ExpressionVisitors.Transformation;
+
+namespace NHibernate.Linq.ExpressionTransformers
+{
+	/// <summary>
+	/// Replace <see cref="string.StartsWith(string)"/>, <see cref="string.EndsWith(string)"/> and <see cref="string.Contains(string)"/>
+	/// with <see cref="SqlMethods.Like(string, string)"/>
+	/// </summary>
+	internal class LikeTransformer : IExpressionTransformer<MethodCallExpression>
+	{
+		private static readonly MethodInfo Like = ReflectHelper.FastGetMethod(SqlMethods.Like, default(string), default(string));
+
+		public ExpressionType[] SupportedExpressionTypes { get; } = {ExpressionType.Call};
+
+		public Expression Transform(MethodCallExpression expression)
+		{
+			if (expression.Method == ReflectionCache.StringMethods.StartsWith)
+			{
+				return Expression.Call(
+					Like,
+					expression.Object,
+					Concat(expression.Arguments[0], Expression.Constant("%"))
+				);
+			}
+
+			if (expression.Method == ReflectionCache.StringMethods.EndsWith)
+			{
+				return Expression.Call(
+					Like,
+					expression.Object,
+					Concat(Expression.Constant("%"), expression.Arguments[0])
+				);
+			}
+
+			if (expression.Method == ReflectionCache.StringMethods.Contains)
+			{
+				return Expression.Call(
+					Like,
+					expression.Object,
+					Concat(Concat(Expression.Constant("%"), expression.Arguments[0]), Expression.Constant("%"))
+				);
+			}
+
+			return expression;
+		}
+
+		private static Expression Concat(Expression arg1, Expression arg2)
+		{
+			if (arg1 is ConstantExpression const1 && arg2 is ConstantExpression const2)
+			{
+				return Expression.Constant(string.Concat(const1.Value, const2.Value));
+			}
+
+			return Expression.Add(arg1, arg2, ReflectionCache.StringMethods.Concat);
+		}
+	}
+}

src/NHibernate/Linq/Functions/StringGenerator.cs

@@ -78,7 +78,7 @@ public class StartsWithGenerator : BaseHqlGeneratorForMethod
 	{
 		public StartsWithGenerator()
 		{
-			SupportedMethods = new[] { ReflectHelper.GetMethodDefinition<string>(x => x.StartsWith(null)) };
+			SupportedMethods = new[] { ReflectionCache.StringMethods.StartsWith };
 		}
 
 		public override bool AllowsNullableReturnType(MethodInfo method) => false;
@@ -97,7 +97,7 @@ public class EndsWithGenerator : BaseHqlGeneratorForMethod
 	{
 		public EndsWithGenerator()
 		{
-			SupportedMethods = new[] { ReflectHelper.GetMethodDefinition<string>(x => x.EndsWith(null)) };
+			SupportedMethods = new[] { ReflectionCache.StringMethods.EndsWith };
 		}
 
 		public override bool AllowsNullableReturnType(MethodInfo method) => false;
@@ -116,7 +116,7 @@ public class ContainsGenerator : BaseHqlGeneratorForMethod
 	{
 		public ContainsGenerator()
 		{
-			SupportedMethods = new[] { ReflectHelper.GetMethodDefinition<string>(x => x.Contains(null)) };
+			SupportedMethods = new[] { ReflectionCache.StringMethods.Contains };
 		}
 
 		public override bool AllowsNullableReturnType(MethodInfo method) => false;

src/NHibernate/Linq/NhRelinqQueryParser.cs

@@ -29,6 +29,7 @@ static NhRelinqQueryParser()
 			// NH-3247: must remove .Net compiler char to int conversion before
 			// parameterization occurs.
 			preTransformerRegistry.Register(new RemoveCharToIntConversion());
+			preTransformerRegistry.Register(new LikeTransformer());
 			PreProcessor = new TransformingExpressionTreeProcessor(preTransformerRegistry);
 
 			var transformerRegistry = ExpressionTransformerRegistry.CreateDefault();

src/NHibernate/Util/ReflectionCache.cs

@@ -222,5 +222,13 @@ internal static class TypeMethods
 			internal static readonly MethodInfo GetTypeFromHandle =
 				ReflectHelper.FastGetMethod(System.Type.GetTypeFromHandle, default(RuntimeTypeHandle));
 		}
+
+		internal static class StringMethods
+		{
+			public static readonly MethodInfo EndsWith = ReflectHelper.GetMethodDefinition<string>(x => x.EndsWith(null));
+			public static readonly MethodInfo StartsWith = ReflectHelper.GetMethodDefinition<string>(x => x.StartsWith(null));
+			public static readonly MethodInfo Contains = ReflectHelper.GetMethodDefinition<string>(x => x.Contains(null));
+			public static readonly MethodInfo Concat = ReflectHelper.FastGetMethod(string.Concat, default(string), default(string));
+		}
 	}
 }