--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/Data/Linq/Builder/ExpressionContext.cs	Thu Mar 27 21:46:09 2014 +0400
@@ -0,0 +1,108 @@
+using System;
+using System.Linq.Expressions;
+
+namespace BLToolkit.Data.Linq.Builder
+{
+	using BLToolkit.Linq;
+	using Data.Sql;
+
+	public class ExpressionContext : SequenceContextBase
+	{
+		public ExpressionContext(IBuildContext parent, IBuildContext sequence, LambdaExpression lambda)
+			: base(parent, sequence, lambda)
+		{
+		}
+
+		public ExpressionContext(IBuildContext parent, IBuildContext sequence, LambdaExpression lambda, SqlQuery sqlQuery)
+			: base(parent, sequence, lambda)
+		{
+			SqlQuery = sqlQuery;
+		}
+
+		public override Expression BuildExpression(Expression expression, int level)
+		{
+			throw new InvalidOperationException();
+		}
+
+		public override SqlInfo[] ConvertToSql(Expression expression, int level, ConvertFlags flags)
+		{
+			if (level == 0)
+			{
+				switch (flags)
+				{
+					case ConvertFlags.Field :
+					case ConvertFlags.Key   :
+					case ConvertFlags.All   :
+						{
+							var root = expression.GetRootObject();
+
+							if (root.NodeType == ExpressionType.Parameter)
+							{
+								var ctx = Builder.GetContext(this, root);
+
+								if (ctx != null)
+								{
+									if (ctx != this)
+										return ctx.ConvertToSql(expression, 0, flags);
+
+									return root == expression ?
+										Sequence.ConvertToSql(null,       0,         flags) :
+										Sequence.ConvertToSql(expression, level + 1, flags);
+								}
+							}
+
+							break;
+						}
+				}
+
+				throw new InvalidOperationException();
+			}
+
+			throw new InvalidOperationException();
+		}
+
+		public override SqlInfo[] ConvertToIndex(Expression expression, int level, ConvertFlags flags)
+		{
+			throw new InvalidOperationException();
+		}
+
+		public override IsExpressionResult IsExpression(Expression expression, int level, RequestFor requestFlag)
+		{
+			switch (requestFlag)
+			{
+				case RequestFor.Root        : return new IsExpressionResult(Lambda.Parameters.Count > 0 && expression == Lambda.Parameters[0]);
+
+				case RequestFor.Table       :
+				case RequestFor.Association :
+				case RequestFor.Object      :
+				case RequestFor.GroupJoin   :
+				case RequestFor.Field       :
+				case RequestFor.Expression  :
+					{
+						var levelExpression = expression.GetLevelExpression(level);
+
+						return levelExpression == expression ?
+							Sequence.IsExpression(null,       0,         requestFlag) :
+							Sequence.IsExpression(expression, level + 1, requestFlag);
+					}
+			}
+
+			return IsExpressionResult.False;
+		}
+
+		public override IBuildContext GetContext(Expression expression, int level, BuildInfo buildInfo)
+		{
+			if (expression == Lambda.Parameters[0])
+				return Sequence.GetContext(null, 0, buildInfo);
+
+			switch (expression.NodeType)
+			{
+				case ExpressionType.Constant   :
+				case ExpressionType.New        :
+				case ExpressionType.MemberInit : return null;
+			}
+
+			return Sequence.GetContext(expression, level + 1, buildInfo);
+		}
+	}
+}