--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Source/Data/Linq/Builder/SequenceContextBase.cs	Thu Mar 27 21:46:09 2014 +0400
@@ -0,0 +1,73 @@
+using System;
+using System.Data;
+using System.Linq.Expressions;
+
+namespace BLToolkit.Data.Linq.Builder
+{
+	using Data.Sql;
+
+	public abstract class SequenceContextBase : IBuildContext
+	{
+		protected SequenceContextBase(IBuildContext parent, IBuildContext sequence, LambdaExpression lambda)
+		{
+			Parent   = parent;
+			Sequence = sequence;
+			Builder  = sequence.Builder;
+			Lambda   = lambda;
+			SqlQuery = sequence.SqlQuery;
+
+			Sequence.Parent = this;
+
+			Builder.Contexts.Add(this);
+		}
+
+#if DEBUG
+		[CLSCompliant(false)]
+		public string _sqlQueryText { get { return SqlQuery == null ? "" : SqlQuery.SqlText; } }
+#endif
+
+		public IBuildContext     Parent   { get; set; }
+		public IBuildContext     Sequence { get; set; }
+		public ExpressionBuilder Builder  { get; set; }
+		public LambdaExpression  Lambda   { get; set; }
+		public SqlQuery          SqlQuery { get; set; }
+
+		Expression IBuildContext.Expression { get { return Lambda; } }
+
+		public virtual void BuildQuery<T>(Query<T> query, ParameterExpression queryParameter)
+		{
+			var expr   = BuildExpression(null, 0);
+			var mapper = Builder.BuildMapper<T>(expr);
+
+			query.SetQuery(mapper.Compile());
+		}
+
+		public abstract Expression         BuildExpression(Expression expression, int level);
+		public abstract SqlInfo[]          ConvertToSql   (Expression expression, int level, ConvertFlags flags);
+		public abstract SqlInfo[]          ConvertToIndex (Expression expression, int level, ConvertFlags flags);
+		public abstract IsExpressionResult IsExpression   (Expression expression, int level, RequestFor requestFlag);
+		public abstract IBuildContext      GetContext     (Expression expression, int level, BuildInfo buildInfo);
+
+		public virtual int ConvertToParentIndex(int index, IBuildContext context)
+		{
+			return Parent == null ? index : Parent.ConvertToParentIndex(index, context);
+		}
+
+		public virtual void SetAlias(string alias)
+		{
+		}
+
+		public virtual ISqlExpression GetSubQuery(IBuildContext context)
+		{
+			return null;
+		}
+
+		protected bool IsSubQuery()
+		{
+			for (var p = Parent; p != null; p = p.Parent)
+				if (p.IsExpression(null, 0, RequestFor.SubQuery).Result)
+					return true;
+			return false;
+		}
+	}
+}