Sql8ConformanceChecker.cs source code in C# .NET

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/ 4.0 / 4.0 / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataEntity / System / Data / SqlClient / SqlGen / Sql8ConformanceChecker.cs / 1305376 / Sql8ConformanceChecker.cs

                            //---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Collections.Generic;
using System.Data.Common;
using System.Data.Common.CommandTrees;
 
namespace System.Data.SqlClient.SqlGen
{ 
    ///  
    /// The Sql8ConformanceChecker walks a DbExpression tree and determines whether
    /// it should be rewritten in order to be translated to SQL appropriate for SQL Server 2000. 
    /// The tree should be rewritten if it contains any of the following expressions:
    /// 
    /// 
    ///  
    /// 
    ///  
    /// 
    /// Also, it throws if it determines that the tree can not
    /// be translated into SQL appropriate for SQL Server 2000. 
    /// This happens if:
    /// 
    /// The tree contains 
    /// The tree contains  with property Limit of type  
    /// The tree contains  with property Count of type 
     ///  
    /// 
    /// The visitor only checks for expressions for which the support differs between SQL Server 2000 and SQL Server 2005,
    /// but does not check/throw for expressions that are not supported for both providers. 
    ///
    /// Implementation note: In the cases when the visitor encounters an expression that requires rewrite,
    /// it still needs to walk its structure in case something below it is not supported and needs to throw.
    /// 
    /// 
    internal class Sql8ConformanceChecker : DbExpressionVisitor 
    { 

        #region 'Public' API 
        /// 
        /// The entry point
        /// 
        ///  
        /// True if the tree needs to be rewriten, false otherwise
        internal static bool NeedsRewrite(DbExpression expr) 
        { 
            Sql8ConformanceChecker checker = new Sql8ConformanceChecker();
            return expr.Accept(checker); 
        }
        #endregion

        #region Constructor 
        /// 
        /// Default Constructor 
        ///  
        private Sql8ConformanceChecker()
        { 
        }
        #endregion

        #region Visitor Helpers 

        ///  
        /// Default handling for DbUnaryExpression-derived classes. Simply visits its argument 
        /// 
        /// The DbUnaryExpression to visit 
        /// 
        private bool VisitUnaryExpression(DbUnaryExpression expr)
        {
            return VisitExpression(expr.Argument); 
        }
 
        ///  
        /// Default handling for DbBinaryExpression-derived classes. Visits both arguments.
        ///  
        /// The DbBinaryExpression to visit
        /// 
        private bool VisitBinaryExpression(DbBinaryExpression expr)
        { 
            bool leftNeedsRewrite = VisitExpression(expr.Left);
            bool rightNeedsRewrite = VisitExpression(expr.Right); 
            return leftNeedsRewrite || rightNeedsRewrite; 
        }
 
        /// 
        /// Used for 
        /// 
        ///  
        /// 
        ///  
        private delegate bool ListElementHandler(TElementType element); 

        ///  
        /// Walks the structure
        /// 
        /// 
        ///  
        private bool VisitAggregate(DbAggregate aggregate)
        { 
            return VisitExpressionList(aggregate.Arguments); 
        }
 
        /// 
        /// DbExpressionBinding handler
        /// 
        ///  
        /// 
        private bool VisitExpressionBinding(DbExpressionBinding expressionBinding) 
        { 
            return VisitExpression(expressionBinding.Expression);
        } 

        /// 
        /// Used as handler for expressions
        ///  
        /// 
        ///  
        private bool VisitExpression(DbExpression expression) 
        {
            if (expression == null) 
            {
                return false;
            }
            return expression.Accept(this); 
        }
 
        ///  
        /// Used as handler for SortClauses
        ///  
        /// 
        /// 
        private bool VisitSortClause(DbSortClause sortClause)
        { 
            return VisitExpression(sortClause.Expression);
        } 
 
        /// 
        /// Helper method for iterating a list 
        /// 
        /// 
        /// 
        ///  
        /// 
        private static bool VisitList(ListElementHandler handler, IList list) 
        { 
            bool result = false;
 
            foreach (TElementType element in list)
            {
                bool localResult = handler(element);
                result = result || localResult; 
            }
            return result; 
        } 

        ///  
        /// Handing for list of s.
        /// 
        /// 
        ///  
        private bool VisitAggregateList(IList list)
        { 
            return VisitList(VisitAggregate, list); 
        }
 
        /// 
        /// Handing for list of s.
        /// 
        ///  
        /// 
        private bool VisitExpressionBindingList(IList list) 
        { 
            return VisitList(VisitExpressionBinding, list);
        } 

        /// 
        /// Handing for list of s.
        ///  
        /// 
        ///  
        private bool VisitExpressionList(IList list) 
        {
            return VisitList(VisitExpression, list); 
        }

        /// 
        /// Handling for list of s. 
        /// 
        ///  
        ///  
        private bool VisitSortClauseList(IList list)
        { 
            return VisitList(VisitSortClause, list);
        }
        #endregion
 
        #region DbExpressionVisitor Members
 
        ///  
        /// Called when an  of an otherwise unrecognized type is encountered.
        ///  
        /// The expression
        /// 
        /// Always thrown if this method is called, since it indicates that  is of an unsupported type
        public override bool Visit(DbExpression expression) 
        {
            throw EntityUtil.NotSupported(System.Data.Entity.Strings.Cqt_General_UnsupportedExpression(expression.GetType().FullName)); 
        } 

        ///  
        /// 
        /// 
        /// The DbAndExpression that is being visited.
        ///  
        public override bool Visit(DbAndExpression expression)
        { 
            return VisitBinaryExpression(expression); 
        }
 
        /// 
        /// Not supported on SQL Server 2000.
        /// 
        /// The DbApplyExpression that is being visited. 
        /// Always
        public override bool Visit(DbApplyExpression expression) 
        { 
            throw EntityUtil.NotSupported(System.Data.Entity.Strings.SqlGen_ApplyNotSupportedOnSql8);
        } 

        /// 
        /// Default handling for DbArithmeticExpression. Visits all arguments.
        ///  
        /// The DbArithmeticExpression that is being visited.
        ///  
        public override bool Visit(DbArithmeticExpression expression) 
        {
            return VisitExpressionList(expression.Arguments); 
        }

        /// 
        /// Walks the strucutre 
        /// 
        /// The DbCaseExpression that is being visited. 
        ///  
        public override bool Visit(DbCaseExpression expression)
        { 
            bool whenNeedsRewrite = VisitExpressionList(expression.When);
            bool thenNeedsRewrite = VisitExpressionList(expression.Then);
            bool elseNeedsRewrite = VisitExpression(expression.Else);
            return whenNeedsRewrite || thenNeedsRewrite || elseNeedsRewrite; 
        }
 
        ///  
        /// 
        ///  
        /// The DbCastExpression that is being visited.
        /// 
        public override bool Visit(DbCastExpression expression)
        { 
            return VisitUnaryExpression(expression);
        } 
 
        /// 
        ///  
        /// 
        /// The DbComparisonExpression that is being visited.
        /// 
        public override bool Visit(DbComparisonExpression expression) 
        {
            return VisitBinaryExpression(expression); 
        } 

        ///  
        /// Returns false
        /// 
        /// The DbConstantExpression that is being visited.
        ///  
        public override bool Visit(DbConstantExpression expression)
        { 
            return false; 
        }
 
        /// 
        /// Walks the structure
        /// 
        /// The DbCrossJoinExpression that is being visited. 
        /// 
        public override bool Visit(DbCrossJoinExpression expression) 
        { 
            return VisitExpressionBindingList(expression.Inputs);
        } 

        /// 
        /// 
        ///  
        /// The DeRefExpression that is being visited.
        ///  
        public override bool Visit(DbDerefExpression expression) 
        {
            return VisitUnaryExpression(expression); 
        }

        /// 
        ///  
        /// 
        /// The DbDistinctExpression that is being visited. 
        ///  
        public override bool Visit(DbDistinctExpression expression)
        { 
            return VisitUnaryExpression(expression);
        }

        ///  
        /// 
        ///  
        /// The DbElementExpression that is being visited. 
        /// 
        public override bool Visit(DbElementExpression expression) 
        {
            return VisitUnaryExpression(expression);
        }
 
        /// 
        ///  
        ///  
        /// The DbEntityRefExpression that is being visited.
        ///  
        public override bool Visit(DbEntityRefExpression expression)
        {
            return VisitUnaryExpression(expression);
        } 

        ///  
        /// Returns true, the tree needs to be rewritten. 
        /// 
        /// The DbExceptExpression that is being visited. 
        /// 
        public override bool Visit(DbExceptExpression expression)
        {
            //Walk the structure in case a non-supported construct is encountered 
            VisitExpression(expression.Left);
            VisitExpression(expression.Right); 
            return true; 
        }
 
        /// 
        /// Walks the structure
        /// 
        /// The DbFilterExpression that is being visited. 
        /// 
        public override bool Visit(DbFilterExpression expression) 
        { 
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input);
            bool predicateNeedsRewrite = VisitExpression(expression.Predicate); 
            return inputNeedsRewrite || predicateNeedsRewrite;
        }

        ///  
        /// Visits the arguments
        ///  
        /// The DbFunctionExpression that is being visited. 
        /// 
        public override bool Visit(DbFunctionExpression expression) 
        {
            return VisitExpressionList(expression.Arguments);
        }
 
        /// 
        /// Visits the arguments and lambda body 
        ///  
        /// The DbLambdaExpression that is being visited.
        ///  
        public override bool Visit(DbLambdaExpression expression)
        {
            bool argumentsNeedRewrite = VisitExpressionList(expression.Arguments);
            bool bodyNeedsRewrite = VisitExpression(expression.Lambda.Body); 

            return argumentsNeedRewrite || bodyNeedsRewrite; 
        } 

        ///  
        /// Walks the structure
        /// 
        /// The DbExpression that is being visited.
        ///  
        public override bool Visit(DbGroupByExpression expression)
        { 
            bool inputNeedsRewrite = VisitExpression(expression.Input.Expression); 
            bool keysNeedRewrite = VisitExpressionList(expression.Keys);
            bool aggregatesNeedRewrite = VisitAggregateList(expression.Aggregates); 

            return inputNeedsRewrite || keysNeedRewrite || aggregatesNeedRewrite;
        }
 
        /// 
        /// Returns true. 
        ///  
        /// The DbIntersectExpression that is being visited.
        ///  
        public override bool Visit(DbIntersectExpression expression)
        {
            //Walk the structure in case a non-supported construct is encountered
            VisitExpression(expression.Left); 
            VisitExpression(expression.Right);
            return true; 
        } 

        ///  
        /// 
        /// 
        /// The DbIsEmptyExpression that is being visited.
        ///  
        public override bool Visit(DbIsEmptyExpression expression)
        { 
            return VisitUnaryExpression(expression); 
        }
 
        /// 
        /// 
        /// 
        /// The DbIsNullExpression that is being visited. 
        /// 
        public override bool Visit(DbIsNullExpression expression) 
        { 
            return VisitUnaryExpression(expression);
        } 

        /// 
        /// 
        ///  
        /// The DbIsOfExpression that is being visited.
        ///  
        public override bool Visit(DbIsOfExpression expression) 
        {
            return VisitUnaryExpression(expression); 
        }

        /// 
        /// Walks the structure 
        /// 
        /// The DbJoinExpression that is being visited. 
        ///  
        public override bool Visit(DbJoinExpression expression)
        { 
            bool leftNeedsRewrite = VisitExpressionBinding(expression.Left);
            bool rightNeedsRewrite = VisitExpressionBinding(expression.Right);
            bool conditionNeedsRewrite = VisitExpression(expression.JoinCondition);
            return leftNeedsRewrite || rightNeedsRewrite || conditionNeedsRewrite; 
        }
 
        ///  
        /// Walks the structure
        ///  
        /// The DbLikeExpression that is being visited.
        /// 
        public override bool Visit(DbLikeExpression expression)
        { 
            bool argumentNeedsRewrite = VisitExpression(expression.Argument);
            bool patternNeedsRewrite = VisitExpression(expression.Pattern); 
            bool excapeNeedsRewrite = VisitExpression(expression.Escape); 
            return argumentNeedsRewrite || patternNeedsRewrite || excapeNeedsRewrite;
        } 

        /// 
        /// Walks the structure
        ///  
        /// 
        ///  
        /// expression.Limit is DbParameterReferenceExpression 
        public override bool Visit(DbLimitExpression expression)
        { 
            if (expression.Limit is DbParameterReferenceExpression)
            {
                throw EntityUtil.NotSupported(System.Data.Entity.Strings.SqlGen_ParameterForLimitNotSupportedOnSql8);
            } 

            return VisitExpression(expression.Argument); 
        } 

 
#if METHOD_EXPRESSION
        /// 
        /// Visitor pattern method for .
        ///  
        /// The MethodExpression that is being visited.
        ///  is null 
        public override bool Visit(MethodExpression expression) 
        {
            bool result = VisitExpressionList(expression.Arguments); 

            if (expression.Instance != null)
            {
               bool instanceNeedsRewrite =  VisitExpression(expression.Instance); 
                result = result || instanceNeedsRewrite;
            } 
            return result; 
        }
#endif 

        /// 
        /// Walks the arguments
        ///  
        /// The DbNewInstanceExpression that is being visited.
        ///  
        public override bool Visit(DbNewInstanceExpression expression) 
        {
            return VisitExpressionList(expression.Arguments); 
        }

        /// 
        ///  
        /// 
        /// The DbNotExpression that is being visited. 
        ///  
        public override bool Visit(DbNotExpression expression)
        { 
            return VisitUnaryExpression(expression);
        }

        ///  
        /// Returns false
        ///  
        /// The DbNullExpression that is being visited. 
        /// false
        public override bool Visit(DbNullExpression expression) 
        {
            return false;
        }
 
        /// 
        ///  
        ///  
        /// The DbOfTypeExpression that is being visited.
        ///  
        public override bool Visit(DbOfTypeExpression expression)
        {
            return VisitUnaryExpression(expression);
        } 

        ///  
        ///  
        /// 
        /// The DbOrExpression that is being visited. 
        /// 
        public override bool Visit(DbOrExpression expression)
        {
            return VisitBinaryExpression(expression); 
        }
 
        ///  
        /// Returns false
        ///  
        /// The DbParameterReferenceExpression that is being visited.
        /// 
        public override bool Visit(DbParameterReferenceExpression expression)
        { 
            return false;
        } 
 
        /// 
        /// Walks the structure 
        /// 
        /// The DbProjectExpression that is being visited.
        /// 
        public override bool Visit(DbProjectExpression expression) 
        {
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input); 
            bool projectionNeedsRewrite = VisitExpression(expression.Projection); 
            return inputNeedsRewrite || projectionNeedsRewrite;
        } 

        /// 
        /// Returns false
        ///  
        /// The DbPropertyExpression that is being visited.
        ///  
        public override bool Visit(DbPropertyExpression expression) 
        {
            return VisitExpression(expression.Instance); 
        }

        /// 
        /// Walks the structure 
        /// 
        /// The DbQuantifierExpression that is being visited. 
        ///  
        public override bool Visit(DbQuantifierExpression expression)
        { 
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input);
            bool predicateNeedsRewrite = VisitExpression(expression.Predicate);
            return inputNeedsRewrite || predicateNeedsRewrite;
        } 

        ///  
        ///  
        /// 
        /// The DbRefExpression that is being visited. 
        /// 
        public override bool Visit(DbRefExpression expression)
        {
            return VisitUnaryExpression(expression); 
        }
 
        ///  
        /// 
        ///  
        /// The DbRefKeyExpression that is being visited.
        /// 
        public override bool Visit(DbRefKeyExpression expression)
        { 
            return VisitUnaryExpression(expression);
        } 
 
        /// 
        /// Walks the structure 
        /// 
        /// The DbRelationshipNavigationExpression that is being visited.
        /// 
        public override bool Visit(DbRelationshipNavigationExpression expression) 
        {
            return VisitExpression(expression.NavigationSource); 
        } 

        ///  
        /// Returns false;
        /// 
        /// The DbScanExpression that is being visited.
        ///  
        public override bool Visit(DbScanExpression expression)
        { 
            return false; 
        }
 
        /// 
        /// Resturns true
        /// 
        ///  
        /// 
        /// expression.Count is DbParameterReferenceExpression 
        public override bool Visit(DbSkipExpression expression) 
        {
            if (expression.Count is DbParameterReferenceExpression) 
            {
                throw EntityUtil.NotSupported(System.Data.Entity.Strings.SqlGen_ParameterForSkipNotSupportedOnSql8);
            }
 
            //Walk the structure in case a non-supported construct is encountered
            VisitExpressionBinding(expression.Input); 
            VisitSortClauseList(expression.SortOrder); 
            VisitExpression(expression.Count);
 
            return true;
        }

        ///  
        /// Walks the structure
        ///  
        /// The DbSortExpression that is being visited. 
        /// 
        public override bool Visit(DbSortExpression expression) 
        {
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input);
            bool sortClauseNeedsRewrite = VisitSortClauseList(expression.SortOrder);
            return inputNeedsRewrite || sortClauseNeedsRewrite; 
        }
 
        ///  
        /// 
        ///  
        /// The DbTreatExpression that is being visited.
        /// 
        public override bool Visit(DbTreatExpression expression)
        { 
            return VisitUnaryExpression(expression);
        } 
 
        /// 
        ///  
        /// 
        /// The DbUnionAllExpression that is being visited.
        /// 
        public override bool Visit(DbUnionAllExpression expression) 
        {
            return VisitBinaryExpression(expression); 
        } 

        ///  
        /// Returns false
        /// 
        /// The DbVariableReferenceExpression that is being visited.
        /// false 
        public override bool Visit(DbVariableReferenceExpression expression)
        { 
            return false; 
        }
 
        #endregion
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
//---------------------------------------------------------------------- 
// 
//      Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// 
// @owner  [....]
// @backupOwner [....] 
//--------------------------------------------------------------------- 

using System; 
using System.Collections.Generic;
using System.Data.Common;
using System.Data.Common.CommandTrees;
 
namespace System.Data.SqlClient.SqlGen
{ 
    ///  
    /// The Sql8ConformanceChecker walks a DbExpression tree and determines whether
    /// it should be rewritten in order to be translated to SQL appropriate for SQL Server 2000. 
    /// The tree should be rewritten if it contains any of the following expressions:
    /// 
    /// 
    ///  
    /// 
    ///  
    /// 
    /// Also, it throws if it determines that the tree can not
    /// be translated into SQL appropriate for SQL Server 2000. 
    /// This happens if:
    /// 
    /// The tree contains 
    /// The tree contains  with property Limit of type  
    /// The tree contains  with property Count of type 
     ///  
    /// 
    /// The visitor only checks for expressions for which the support differs between SQL Server 2000 and SQL Server 2005,
    /// but does not check/throw for expressions that are not supported for both providers. 
    ///
    /// Implementation note: In the cases when the visitor encounters an expression that requires rewrite,
    /// it still needs to walk its structure in case something below it is not supported and needs to throw.
    /// 
    /// 
    internal class Sql8ConformanceChecker : DbExpressionVisitor 
    { 

        #region 'Public' API 
        /// 
        /// The entry point
        /// 
        ///  
        /// True if the tree needs to be rewriten, false otherwise
        internal static bool NeedsRewrite(DbExpression expr) 
        { 
            Sql8ConformanceChecker checker = new Sql8ConformanceChecker();
            return expr.Accept(checker); 
        }
        #endregion

        #region Constructor 
        /// 
        /// Default Constructor 
        ///  
        private Sql8ConformanceChecker()
        { 
        }
        #endregion

        #region Visitor Helpers 

        ///  
        /// Default handling for DbUnaryExpression-derived classes. Simply visits its argument 
        /// 
        /// The DbUnaryExpression to visit 
        /// 
        private bool VisitUnaryExpression(DbUnaryExpression expr)
        {
            return VisitExpression(expr.Argument); 
        }
 
        ///  
        /// Default handling for DbBinaryExpression-derived classes. Visits both arguments.
        ///  
        /// The DbBinaryExpression to visit
        /// 
        private bool VisitBinaryExpression(DbBinaryExpression expr)
        { 
            bool leftNeedsRewrite = VisitExpression(expr.Left);
            bool rightNeedsRewrite = VisitExpression(expr.Right); 
            return leftNeedsRewrite || rightNeedsRewrite; 
        }
 
        /// 
        /// Used for 
        /// 
        ///  
        /// 
        ///  
        private delegate bool ListElementHandler(TElementType element); 

        ///  
        /// Walks the structure
        /// 
        /// 
        ///  
        private bool VisitAggregate(DbAggregate aggregate)
        { 
            return VisitExpressionList(aggregate.Arguments); 
        }
 
        /// 
        /// DbExpressionBinding handler
        /// 
        ///  
        /// 
        private bool VisitExpressionBinding(DbExpressionBinding expressionBinding) 
        { 
            return VisitExpression(expressionBinding.Expression);
        } 

        /// 
        /// Used as handler for expressions
        ///  
        /// 
        ///  
        private bool VisitExpression(DbExpression expression) 
        {
            if (expression == null) 
            {
                return false;
            }
            return expression.Accept(this); 
        }
 
        ///  
        /// Used as handler for SortClauses
        ///  
        /// 
        /// 
        private bool VisitSortClause(DbSortClause sortClause)
        { 
            return VisitExpression(sortClause.Expression);
        } 
 
        /// 
        /// Helper method for iterating a list 
        /// 
        /// 
        /// 
        ///  
        /// 
        private static bool VisitList(ListElementHandler handler, IList list) 
        { 
            bool result = false;
 
            foreach (TElementType element in list)
            {
                bool localResult = handler(element);
                result = result || localResult; 
            }
            return result; 
        } 

        ///  
        /// Handing for list of s.
        /// 
        /// 
        ///  
        private bool VisitAggregateList(IList list)
        { 
            return VisitList(VisitAggregate, list); 
        }
 
        /// 
        /// Handing for list of s.
        /// 
        ///  
        /// 
        private bool VisitExpressionBindingList(IList list) 
        { 
            return VisitList(VisitExpressionBinding, list);
        } 

        /// 
        /// Handing for list of s.
        ///  
        /// 
        ///  
        private bool VisitExpressionList(IList list) 
        {
            return VisitList(VisitExpression, list); 
        }

        /// 
        /// Handling for list of s. 
        /// 
        ///  
        ///  
        private bool VisitSortClauseList(IList list)
        { 
            return VisitList(VisitSortClause, list);
        }
        #endregion
 
        #region DbExpressionVisitor Members
 
        ///  
        /// Called when an  of an otherwise unrecognized type is encountered.
        ///  
        /// The expression
        /// 
        /// Always thrown if this method is called, since it indicates that  is of an unsupported type
        public override bool Visit(DbExpression expression) 
        {
            throw EntityUtil.NotSupported(System.Data.Entity.Strings.Cqt_General_UnsupportedExpression(expression.GetType().FullName)); 
        } 

        ///  
        /// 
        /// 
        /// The DbAndExpression that is being visited.
        ///  
        public override bool Visit(DbAndExpression expression)
        { 
            return VisitBinaryExpression(expression); 
        }
 
        /// 
        /// Not supported on SQL Server 2000.
        /// 
        /// The DbApplyExpression that is being visited. 
        /// Always
        public override bool Visit(DbApplyExpression expression) 
        { 
            throw EntityUtil.NotSupported(System.Data.Entity.Strings.SqlGen_ApplyNotSupportedOnSql8);
        } 

        /// 
        /// Default handling for DbArithmeticExpression. Visits all arguments.
        ///  
        /// The DbArithmeticExpression that is being visited.
        ///  
        public override bool Visit(DbArithmeticExpression expression) 
        {
            return VisitExpressionList(expression.Arguments); 
        }

        /// 
        /// Walks the strucutre 
        /// 
        /// The DbCaseExpression that is being visited. 
        ///  
        public override bool Visit(DbCaseExpression expression)
        { 
            bool whenNeedsRewrite = VisitExpressionList(expression.When);
            bool thenNeedsRewrite = VisitExpressionList(expression.Then);
            bool elseNeedsRewrite = VisitExpression(expression.Else);
            return whenNeedsRewrite || thenNeedsRewrite || elseNeedsRewrite; 
        }
 
        ///  
        /// 
        ///  
        /// The DbCastExpression that is being visited.
        /// 
        public override bool Visit(DbCastExpression expression)
        { 
            return VisitUnaryExpression(expression);
        } 
 
        /// 
        ///  
        /// 
        /// The DbComparisonExpression that is being visited.
        /// 
        public override bool Visit(DbComparisonExpression expression) 
        {
            return VisitBinaryExpression(expression); 
        } 

        ///  
        /// Returns false
        /// 
        /// The DbConstantExpression that is being visited.
        ///  
        public override bool Visit(DbConstantExpression expression)
        { 
            return false; 
        }
 
        /// 
        /// Walks the structure
        /// 
        /// The DbCrossJoinExpression that is being visited. 
        /// 
        public override bool Visit(DbCrossJoinExpression expression) 
        { 
            return VisitExpressionBindingList(expression.Inputs);
        } 

        /// 
        /// 
        ///  
        /// The DeRefExpression that is being visited.
        ///  
        public override bool Visit(DbDerefExpression expression) 
        {
            return VisitUnaryExpression(expression); 
        }

        /// 
        ///  
        /// 
        /// The DbDistinctExpression that is being visited. 
        ///  
        public override bool Visit(DbDistinctExpression expression)
        { 
            return VisitUnaryExpression(expression);
        }

        ///  
        /// 
        ///  
        /// The DbElementExpression that is being visited. 
        /// 
        public override bool Visit(DbElementExpression expression) 
        {
            return VisitUnaryExpression(expression);
        }
 
        /// 
        ///  
        ///  
        /// The DbEntityRefExpression that is being visited.
        ///  
        public override bool Visit(DbEntityRefExpression expression)
        {
            return VisitUnaryExpression(expression);
        } 

        ///  
        /// Returns true, the tree needs to be rewritten. 
        /// 
        /// The DbExceptExpression that is being visited. 
        /// 
        public override bool Visit(DbExceptExpression expression)
        {
            //Walk the structure in case a non-supported construct is encountered 
            VisitExpression(expression.Left);
            VisitExpression(expression.Right); 
            return true; 
        }
 
        /// 
        /// Walks the structure
        /// 
        /// The DbFilterExpression that is being visited. 
        /// 
        public override bool Visit(DbFilterExpression expression) 
        { 
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input);
            bool predicateNeedsRewrite = VisitExpression(expression.Predicate); 
            return inputNeedsRewrite || predicateNeedsRewrite;
        }

        ///  
        /// Visits the arguments
        ///  
        /// The DbFunctionExpression that is being visited. 
        /// 
        public override bool Visit(DbFunctionExpression expression) 
        {
            return VisitExpressionList(expression.Arguments);
        }
 
        /// 
        /// Visits the arguments and lambda body 
        ///  
        /// The DbLambdaExpression that is being visited.
        ///  
        public override bool Visit(DbLambdaExpression expression)
        {
            bool argumentsNeedRewrite = VisitExpressionList(expression.Arguments);
            bool bodyNeedsRewrite = VisitExpression(expression.Lambda.Body); 

            return argumentsNeedRewrite || bodyNeedsRewrite; 
        } 

        ///  
        /// Walks the structure
        /// 
        /// The DbExpression that is being visited.
        ///  
        public override bool Visit(DbGroupByExpression expression)
        { 
            bool inputNeedsRewrite = VisitExpression(expression.Input.Expression); 
            bool keysNeedRewrite = VisitExpressionList(expression.Keys);
            bool aggregatesNeedRewrite = VisitAggregateList(expression.Aggregates); 

            return inputNeedsRewrite || keysNeedRewrite || aggregatesNeedRewrite;
        }
 
        /// 
        /// Returns true. 
        ///  
        /// The DbIntersectExpression that is being visited.
        ///  
        public override bool Visit(DbIntersectExpression expression)
        {
            //Walk the structure in case a non-supported construct is encountered
            VisitExpression(expression.Left); 
            VisitExpression(expression.Right);
            return true; 
        } 

        ///  
        /// 
        /// 
        /// The DbIsEmptyExpression that is being visited.
        ///  
        public override bool Visit(DbIsEmptyExpression expression)
        { 
            return VisitUnaryExpression(expression); 
        }
 
        /// 
        /// 
        /// 
        /// The DbIsNullExpression that is being visited. 
        /// 
        public override bool Visit(DbIsNullExpression expression) 
        { 
            return VisitUnaryExpression(expression);
        } 

        /// 
        /// 
        ///  
        /// The DbIsOfExpression that is being visited.
        ///  
        public override bool Visit(DbIsOfExpression expression) 
        {
            return VisitUnaryExpression(expression); 
        }

        /// 
        /// Walks the structure 
        /// 
        /// The DbJoinExpression that is being visited. 
        ///  
        public override bool Visit(DbJoinExpression expression)
        { 
            bool leftNeedsRewrite = VisitExpressionBinding(expression.Left);
            bool rightNeedsRewrite = VisitExpressionBinding(expression.Right);
            bool conditionNeedsRewrite = VisitExpression(expression.JoinCondition);
            return leftNeedsRewrite || rightNeedsRewrite || conditionNeedsRewrite; 
        }
 
        ///  
        /// Walks the structure
        ///  
        /// The DbLikeExpression that is being visited.
        /// 
        public override bool Visit(DbLikeExpression expression)
        { 
            bool argumentNeedsRewrite = VisitExpression(expression.Argument);
            bool patternNeedsRewrite = VisitExpression(expression.Pattern); 
            bool excapeNeedsRewrite = VisitExpression(expression.Escape); 
            return argumentNeedsRewrite || patternNeedsRewrite || excapeNeedsRewrite;
        } 

        /// 
        /// Walks the structure
        ///  
        /// 
        ///  
        /// expression.Limit is DbParameterReferenceExpression 
        public override bool Visit(DbLimitExpression expression)
        { 
            if (expression.Limit is DbParameterReferenceExpression)
            {
                throw EntityUtil.NotSupported(System.Data.Entity.Strings.SqlGen_ParameterForLimitNotSupportedOnSql8);
            } 

            return VisitExpression(expression.Argument); 
        } 

 
#if METHOD_EXPRESSION
        /// 
        /// Visitor pattern method for .
        ///  
        /// The MethodExpression that is being visited.
        ///  is null 
        public override bool Visit(MethodExpression expression) 
        {
            bool result = VisitExpressionList(expression.Arguments); 

            if (expression.Instance != null)
            {
               bool instanceNeedsRewrite =  VisitExpression(expression.Instance); 
                result = result || instanceNeedsRewrite;
            } 
            return result; 
        }
#endif 

        /// 
        /// Walks the arguments
        ///  
        /// The DbNewInstanceExpression that is being visited.
        ///  
        public override bool Visit(DbNewInstanceExpression expression) 
        {
            return VisitExpressionList(expression.Arguments); 
        }

        /// 
        ///  
        /// 
        /// The DbNotExpression that is being visited. 
        ///  
        public override bool Visit(DbNotExpression expression)
        { 
            return VisitUnaryExpression(expression);
        }

        ///  
        /// Returns false
        ///  
        /// The DbNullExpression that is being visited. 
        /// false
        public override bool Visit(DbNullExpression expression) 
        {
            return false;
        }
 
        /// 
        ///  
        ///  
        /// The DbOfTypeExpression that is being visited.
        ///  
        public override bool Visit(DbOfTypeExpression expression)
        {
            return VisitUnaryExpression(expression);
        } 

        ///  
        ///  
        /// 
        /// The DbOrExpression that is being visited. 
        /// 
        public override bool Visit(DbOrExpression expression)
        {
            return VisitBinaryExpression(expression); 
        }
 
        ///  
        /// Returns false
        ///  
        /// The DbParameterReferenceExpression that is being visited.
        /// 
        public override bool Visit(DbParameterReferenceExpression expression)
        { 
            return false;
        } 
 
        /// 
        /// Walks the structure 
        /// 
        /// The DbProjectExpression that is being visited.
        /// 
        public override bool Visit(DbProjectExpression expression) 
        {
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input); 
            bool projectionNeedsRewrite = VisitExpression(expression.Projection); 
            return inputNeedsRewrite || projectionNeedsRewrite;
        } 

        /// 
        /// Returns false
        ///  
        /// The DbPropertyExpression that is being visited.
        ///  
        public override bool Visit(DbPropertyExpression expression) 
        {
            return VisitExpression(expression.Instance); 
        }

        /// 
        /// Walks the structure 
        /// 
        /// The DbQuantifierExpression that is being visited. 
        ///  
        public override bool Visit(DbQuantifierExpression expression)
        { 
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input);
            bool predicateNeedsRewrite = VisitExpression(expression.Predicate);
            return inputNeedsRewrite || predicateNeedsRewrite;
        } 

        ///  
        ///  
        /// 
        /// The DbRefExpression that is being visited. 
        /// 
        public override bool Visit(DbRefExpression expression)
        {
            return VisitUnaryExpression(expression); 
        }
 
        ///  
        /// 
        ///  
        /// The DbRefKeyExpression that is being visited.
        /// 
        public override bool Visit(DbRefKeyExpression expression)
        { 
            return VisitUnaryExpression(expression);
        } 
 
        /// 
        /// Walks the structure 
        /// 
        /// The DbRelationshipNavigationExpression that is being visited.
        /// 
        public override bool Visit(DbRelationshipNavigationExpression expression) 
        {
            return VisitExpression(expression.NavigationSource); 
        } 

        ///  
        /// Returns false;
        /// 
        /// The DbScanExpression that is being visited.
        ///  
        public override bool Visit(DbScanExpression expression)
        { 
            return false; 
        }
 
        /// 
        /// Resturns true
        /// 
        ///  
        /// 
        /// expression.Count is DbParameterReferenceExpression 
        public override bool Visit(DbSkipExpression expression) 
        {
            if (expression.Count is DbParameterReferenceExpression) 
            {
                throw EntityUtil.NotSupported(System.Data.Entity.Strings.SqlGen_ParameterForSkipNotSupportedOnSql8);
            }
 
            //Walk the structure in case a non-supported construct is encountered
            VisitExpressionBinding(expression.Input); 
            VisitSortClauseList(expression.SortOrder); 
            VisitExpression(expression.Count);
 
            return true;
        }

        ///  
        /// Walks the structure
        ///  
        /// The DbSortExpression that is being visited. 
        /// 
        public override bool Visit(DbSortExpression expression) 
        {
            bool inputNeedsRewrite = VisitExpressionBinding(expression.Input);
            bool sortClauseNeedsRewrite = VisitSortClauseList(expression.SortOrder);
            return inputNeedsRewrite || sortClauseNeedsRewrite; 
        }
 
        ///  
        /// 
        ///  
        /// The DbTreatExpression that is being visited.
        /// 
        public override bool Visit(DbTreatExpression expression)
        { 
            return VisitUnaryExpression(expression);
        } 
 
        /// 
        ///  
        /// 
        /// The DbUnionAllExpression that is being visited.
        /// 
        public override bool Visit(DbUnionAllExpression expression) 
        {
            return VisitBinaryExpression(expression); 
        } 

        ///  
        /// Returns false
        /// 
        /// The DbVariableReferenceExpression that is being visited.
        /// false 
        public override bool Visit(DbVariableReferenceExpression expression)
        { 
            return false; 
        }
 
        #endregion
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
                        

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