ALinqExpressionVisitor.cs source code in C# .NET

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Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / fx / src / DataWeb / Client / System / Data / Services / Client / ALinq / ALinqExpressionVisitor.cs / 1305376 / ALinqExpressionVisitor.cs
                        

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

#if ASTORIA_SERVER
namespace System.Data.Services
#else 
namespace System.Data.Services.Client
#endif 
{ 
    using System;
    using System.Collections.Generic; 
    using System.Collections.ObjectModel;
    using System.Linq.Expressions;
#if ASTORIA_LIGHT
    using System.Reflection; 
    using System.Security;
    using System.Security.Permissions; 
 
    /// 
    /// This class introduced because of a bug in SL3 which prevents using non-public (e.g anonymous) types as return types for lambdas 
    /// We should be able to remove this for SL4.
    /// 
    internal static class ExpressionHelpers
    { 
        private static MethodInfo lambdaFunc;
        internal static LambdaExpression CreateLambda(Expression body, params ParameterExpression[] parameters) 
        { 
            return CreateLambda(InferDelegateType(body, parameters), body, parameters);
        } 

        // This creates a tree and compiles it just for the purposes of creating the real lambda
        internal static LambdaExpression CreateLambda(Type delegateType, Expression body, params ParameterExpression[] parameters)
        { 
            // Expression.Lambda() doesn't work directly if "body" is a non-public type
            // Work around this by calling the factory from a DynamicMethod. 
 
            var args = new[] { Expression.Parameter(typeof(Expression), "body"), Expression.Parameter(typeof(ParameterExpression[]), "parameters") };
 
            var lambdaFactory = Expression.Lambda>(
                Expression.Call(GetLambdaFactoryMethod(delegateType), args), args
            );
 
            return lambdaFactory.Compile().Invoke(body, parameters);
        } 
 
        private static Type InferDelegateType(Expression body, params ParameterExpression[] parameters)
        { 
            bool isVoid = body.Type == typeof(void);
            int length = (parameters == null) ? 0 : parameters.Length;

            var typeArgs = new Type[length + (isVoid ? 0 : 1)]; 
            for (int i = 0; i < length; i++)
            { 
                typeArgs[i] = parameters[i].Type; 
            }
            if (isVoid) 
            {
                return Expression.GetActionType(typeArgs);
            }
            else 
            {
                typeArgs[length] = body.Type; 
                return Expression.GetFuncType(typeArgs); 
            }
        } 

        private static MethodInfo GetLambdaFactoryMethod(Type delegateType)
        {
            // Gets the MethodInfo for Expression.Lambda(Expression body, params ParameterExpression[] parameters) 
            if (lambdaFunc == null)
            { 
                lambdaFunc = new Func>(Expression.Lambda).Method.GetGenericMethodDefinition(); 
            }
 
            //Create a throwaway delegate to bind to the right Labda function with a specific delegate type.
            return lambdaFunc.MakeGenericMethod(delegateType);
        }
    } 
#endif
 
    ///  
    /// base vistor class for walking an expression tree bottom up.
    ///  
    internal abstract class ALinqExpressionVisitor
    {
        /// 
        /// Main visit method for ALinqExpressionVisitor 
        /// 
        /// The expression to visit 
        /// The visited expression  
        internal virtual Expression Visit(Expression exp)
        { 
            if (exp == null)
            {
                return exp;
            } 

            switch (exp.NodeType) 
            { 
                case ExpressionType.UnaryPlus:
                case ExpressionType.Negate: 
                case ExpressionType.NegateChecked:
                case ExpressionType.Not:
                case ExpressionType.Convert:
                case ExpressionType.ConvertChecked: 
                case ExpressionType.ArrayLength:
                case ExpressionType.Quote: 
                case ExpressionType.TypeAs: 
                    return this.VisitUnary((UnaryExpression)exp);
                case ExpressionType.Add: 
                case ExpressionType.AddChecked:
                case ExpressionType.Subtract:
                case ExpressionType.SubtractChecked:
                case ExpressionType.Multiply: 
                case ExpressionType.MultiplyChecked:
                case ExpressionType.Divide: 
                case ExpressionType.Modulo: 
#if !ASTORIA_CLIENT
                case ExpressionType.Power: 
#endif
                case ExpressionType.And:
                case ExpressionType.AndAlso:
                case ExpressionType.Or: 
                case ExpressionType.OrElse:
                case ExpressionType.LessThan: 
                case ExpressionType.LessThanOrEqual: 
                case ExpressionType.GreaterThan:
                case ExpressionType.GreaterThanOrEqual: 
                case ExpressionType.Equal:
                case ExpressionType.NotEqual:
                case ExpressionType.Coalesce:
                case ExpressionType.ArrayIndex: 
                case ExpressionType.RightShift:
                case ExpressionType.LeftShift: 
                case ExpressionType.ExclusiveOr: 
                    return this.VisitBinary((BinaryExpression)exp);
                case ExpressionType.TypeIs: 
                    return this.VisitTypeIs((TypeBinaryExpression)exp);
                case ExpressionType.Conditional:
                    return this.VisitConditional((ConditionalExpression)exp);
                case ExpressionType.Constant: 
                    return this.VisitConstant((ConstantExpression)exp);
                case ExpressionType.Parameter: 
                    return this.VisitParameter((ParameterExpression)exp); 
                case ExpressionType.MemberAccess:
                    return this.VisitMemberAccess((MemberExpression)exp); 
                case ExpressionType.Call:
                    return this.VisitMethodCall((MethodCallExpression)exp);
                case ExpressionType.Lambda:
                    return this.VisitLambda((LambdaExpression)exp); 
                case ExpressionType.New:
                    return this.VisitNew((NewExpression)exp); 
                case ExpressionType.NewArrayInit: 
                case ExpressionType.NewArrayBounds:
                    return this.VisitNewArray((NewArrayExpression)exp); 
                case ExpressionType.Invoke:
                    return this.VisitInvocation((InvocationExpression)exp);
                case ExpressionType.MemberInit:
                    return this.VisitMemberInit((MemberInitExpression)exp); 
                case ExpressionType.ListInit:
                    return this.VisitListInit((ListInitExpression)exp); 
                default: 
                    throw new NotSupportedException(Strings.ALinq_UnsupportedExpression(exp.NodeType.ToString()));
            } 
        }

        /// 
        /// MemberBinding visit method 
        /// 
        /// The MemberBinding expression to visit 
        /// The visited MemberBinding expression  
        internal virtual MemberBinding VisitBinding(MemberBinding binding)
        { 
            switch (binding.BindingType)
            {
                case MemberBindingType.Assignment:
                    return this.VisitMemberAssignment((MemberAssignment)binding); 
                case MemberBindingType.MemberBinding:
                    return this.VisitMemberMemberBinding((MemberMemberBinding)binding); 
                case MemberBindingType.ListBinding: 
                    return this.VisitMemberListBinding((MemberListBinding)binding);
                default: 
                    throw new NotSupportedException(Strings.ALinq_UnsupportedExpression(binding.BindingType.ToString()));
            }
        }
 
        /// 
        /// ElementInit visit method 
        ///  
        /// The ElementInit expression to visit
        /// The visited ElementInit expression  
        internal virtual ElementInit VisitElementInitializer(ElementInit initializer)
        {
            ReadOnlyCollection arguments = this.VisitExpressionList(initializer.Arguments);
            if (arguments != initializer.Arguments) 
            {
                return Expression.ElementInit(initializer.AddMethod, arguments); 
            } 

            return initializer; 
        }

        /// 
        /// UnaryExpression visit method 
        /// 
        /// The UnaryExpression expression to visit 
        /// The visited UnaryExpression expression  
        internal virtual Expression VisitUnary(UnaryExpression u)
        { 
            Expression operand = this.Visit(u.Operand);
            if (operand != u.Operand)
            {
                return Expression.MakeUnary(u.NodeType, operand, u.Type, u.Method); 
            }
 
            return u; 
        }
 
        /// 
        /// BinaryExpression visit method
        /// 
        /// The BinaryExpression expression to visit 
        /// The visited BinaryExpression expression 
        internal virtual Expression VisitBinary(BinaryExpression b) 
        { 
            Expression left = this.Visit(b.Left);
            Expression right = this.Visit(b.Right); 
            Expression conversion = this.Visit(b.Conversion);
            if (left != b.Left || right != b.Right || conversion != b.Conversion)
            {
                if (b.NodeType == ExpressionType.Coalesce && b.Conversion != null) 
                {
                    return Expression.Coalesce(left, right, conversion as LambdaExpression); 
                } 
                else
                { 
                    return Expression.MakeBinary(b.NodeType, left, right, b.IsLiftedToNull, b.Method);
                }
            }
 
            return b;
        } 
 
        /// 
        /// TypeBinaryExpression visit method 
        /// 
        /// The TypeBinaryExpression expression to visit
        /// The visited TypeBinaryExpression expression 
        internal virtual Expression VisitTypeIs(TypeBinaryExpression b) 
        {
            Expression expr = this.Visit(b.Expression); 
            if (expr != b.Expression) 
            {
                return Expression.TypeIs(expr, b.TypeOperand); 
            }

            return b;
        } 

        ///  
        /// ConstantExpression visit method 
        /// 
        /// The ConstantExpression expression to visit 
        /// The visited ConstantExpression expression 
        internal virtual Expression VisitConstant(ConstantExpression c)
        {
            return c; 
        }
 
        ///  
        /// ConditionalExpression visit method
        ///  
        /// The ConditionalExpression expression to visit
        /// The visited ConditionalExpression expression 
        internal virtual Expression VisitConditional(ConditionalExpression c)
        { 
            Expression test = this.Visit(c.Test);
            Expression iftrue = this.Visit(c.IfTrue); 
            Expression iffalse = this.Visit(c.IfFalse); 
            if (test != c.Test || iftrue != c.IfTrue || iffalse != c.IfFalse)
            { 
                return Expression.Condition(test, iftrue, iffalse);
            }

            return c; 
        }
 
        ///  
        /// ParameterExpression visit method
        ///  
        /// The ParameterExpression expression to visit
        /// The visited ParameterExpression expression 
        internal virtual Expression VisitParameter(ParameterExpression p)
        { 
            return p;
        } 
 
        /// 
        /// MemberExpression visit method 
        /// 
        /// The MemberExpression expression to visit
        /// The visited MemberExpression expression 
        internal virtual Expression VisitMemberAccess(MemberExpression m) 
        {
            Expression exp = this.Visit(m.Expression); 
            if (exp != m.Expression) 
            {
                return Expression.MakeMemberAccess(exp, m.Member); 
            }

            return m;
        } 

        ///  
        /// MethodCallExpression visit method 
        /// 
        /// The MethodCallExpression expression to visit 
        /// The visited MethodCallExpression expression 
        internal virtual Expression VisitMethodCall(MethodCallExpression m)
        {
            Expression obj = this.Visit(m.Object); 
            IEnumerable args = this.VisitExpressionList(m.Arguments);
            if (obj != m.Object || args != m.Arguments) 
            { 
                return Expression.Call(obj, m.Method, args);
            } 

            return m;
        }
 
        /// 
        /// Expression list visit method 
        ///  
        /// The expression list to visit
        /// The visited expression list 
        internal virtual ReadOnlyCollection VisitExpressionList(ReadOnlyCollection original)
        {
            List list = null;
            for (int i = 0, n = original.Count; i < n; i++) 
            {
                Expression p = this.Visit(original[i]); 
                if (list != null) 
                {
                    list.Add(p); 
                }
                else if (p != original[i])
                {
                    list = new List(n); 
                    for (int j = 0; j < i; j++)
                    { 
                        list.Add(original[j]); 
                    }
 
                    list.Add(p);
                }
            }
 
            if (list != null)
            { 
                return new ReadOnlyCollection(list); 
            }
 
            return original;
        }

        ///  
        /// MemberAssignment visit method
        ///  
        /// The MemberAssignment to visit 
        /// The visited MemberAssignmentt
        internal virtual MemberAssignment VisitMemberAssignment(MemberAssignment assignment) 
        {
            Expression e = this.Visit(assignment.Expression);
            if (e != assignment.Expression)
            { 
                return Expression.Bind(assignment.Member, e);
            } 
 
            return assignment;
        } 

        /// 
        /// MemberMemberBinding visit method
        ///  
        /// The MemberMemberBinding to visit
        /// The visited MemberMemberBinding 
        internal virtual MemberMemberBinding VisitMemberMemberBinding(MemberMemberBinding binding) 
        {
            IEnumerable bindings = this.VisitBindingList(binding.Bindings); 
            if (bindings != binding.Bindings)
            {
                return Expression.MemberBind(binding.Member, bindings);
            } 

            return binding; 
        } 

        ///  
        /// MemberListBinding visit method
        /// 
        /// The MemberListBinding to visit
        /// The visited MemberListBinding 
        internal virtual MemberListBinding VisitMemberListBinding(MemberListBinding binding)
        { 
            IEnumerable initializers = this.VisitElementInitializerList(binding.Initializers); 
            if (initializers != binding.Initializers)
            { 
                return Expression.ListBind(binding.Member, initializers);
            }

            return binding; 
        }
 
        ///  
        /// Binding List visit method
        ///  
        /// The Binding list to visit
        /// The visited Binding list
        internal virtual IEnumerable VisitBindingList(ReadOnlyCollection original)
        { 
            List list = null;
            for (int i = 0, n = original.Count; i < n; i++) 
            { 
                MemberBinding b = this.VisitBinding(original[i]);
                if (list != null) 
                {
                    list.Add(b);
                }
                else if (b != original[i]) 
                {
                    list = new List(n); 
                    for (int j = 0; j < i; j++) 
                    {
                        list.Add(original[j]); 
                    }

                    list.Add(b);
                } 
            }
 
            if (list != null) 
            {
                return list; 
            }

            return original;
        } 

        ///  
        /// ElementInit expression list visit method 
        /// 
        /// The ElementInit expression list  to visit 
        /// The visited ElementInit expression list 
        internal virtual IEnumerable VisitElementInitializerList(ReadOnlyCollection original)
        {
            List list = null; 
            for (int i = 0, n = original.Count; i < n; i++)
            { 
                ElementInit init = this.VisitElementInitializer(original[i]); 
                if (list != null)
                { 
                    list.Add(init);
                }
                else if (init != original[i])
                { 
                    list = new List(n);
                    for (int j = 0; j < i; j++) 
                    { 
                        list.Add(original[j]);
                    } 

                    list.Add(init);
                }
            } 

            if (list != null) 
            { 
                return list;
            } 

            return original;
        }
 
        /// 
        /// LambdaExpression visit method 
        ///  
        /// The LambdaExpression to visit
        /// The visited LambdaExpression 
        internal virtual Expression VisitLambda(LambdaExpression lambda)
        {
            Expression body = this.Visit(lambda.Body);
            if (body != lambda.Body) 
            {
#if !ASTORIA_LIGHT 
                return Expression.Lambda(lambda.Type, body, lambda.Parameters); 
#else
                ParameterExpression[] parameters = new ParameterExpression[lambda.Parameters.Count]; 
                lambda.Parameters.CopyTo(parameters, 0);
                return ExpressionHelpers.CreateLambda(lambda.Type, body, parameters);
#endif
            } 

            return lambda; 
        } 

        ///  
        /// NewExpression visit method
        /// 
        /// The NewExpression to visit
        /// The visited NewExpression 
        internal virtual NewExpression VisitNew(NewExpression nex)
        { 
            IEnumerable args = this.VisitExpressionList(nex.Arguments); 
            if (args != nex.Arguments)
            { 
                if (nex.Members != null)
                {
                    return Expression.New(nex.Constructor, args, nex.Members);
                } 
                else
                { 
                    return Expression.New(nex.Constructor, args); 
                }
            } 

            return nex;
        }
 
        /// 
        /// MemberInitExpression visit method 
        ///  
        /// The MemberInitExpression to visit
        /// The visited MemberInitExpression 
        internal virtual Expression VisitMemberInit(MemberInitExpression init)
        {
            NewExpression n = this.VisitNew(init.NewExpression);
            IEnumerable bindings = this.VisitBindingList(init.Bindings); 
            if (n != init.NewExpression || bindings != init.Bindings)
            { 
                return Expression.MemberInit(n, bindings); 
            }
 
            return init;
        }

        ///  
        /// ListInitExpression visit method
        ///  
        /// The ListInitExpression to visit 
        /// The visited ListInitExpression
        internal virtual Expression VisitListInit(ListInitExpression init) 
        {
            NewExpression n = this.VisitNew(init.NewExpression);
            IEnumerable initializers = this.VisitElementInitializerList(init.Initializers);
            if (n != init.NewExpression || initializers != init.Initializers) 
            {
                return Expression.ListInit(n, initializers); 
            } 

            return init; 
        }

        /// 
        /// NewArrayExpression visit method 
        /// 
        /// The NewArrayExpression to visit 
        /// The visited NewArrayExpression 
        internal virtual Expression VisitNewArray(NewArrayExpression na)
        { 
            IEnumerable exprs = this.VisitExpressionList(na.Expressions);
            if (exprs != na.Expressions)
            {
                if (na.NodeType == ExpressionType.NewArrayInit) 
                {
                    return Expression.NewArrayInit(na.Type.GetElementType(), exprs); 
                } 
                else
                { 
                    return Expression.NewArrayBounds(na.Type.GetElementType(), exprs);
                }
            }
 
            return na;
        } 
 
        /// 
        /// InvocationExpression visit method 
        /// 
        /// The InvocationExpression to visit
        /// The visited InvocationExpression
        internal virtual Expression VisitInvocation(InvocationExpression iv) 
        {
            IEnumerable args = this.VisitExpressionList(iv.Arguments); 
            Expression expr = this.Visit(iv.Expression); 
            if (args != iv.Arguments || expr != iv.Expression)
            { 
                return Expression.Invoke(expr, args);
            }

            return iv; 
        }
    } 
} 

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

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