VisualBasicDesignerHelper.cs source code in C# .NET

Source code for the .NET framework in C#

                        

Code:

/ 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx40 / System.Activities / Microsoft / VisualBasic / Activities / VisualBasicDesignerHelper.cs / 1305376 / VisualBasicDesignerHelper.cs

                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace Microsoft.VisualBasic.Activities 
{
    using System; 
    using System.Activities; 
    using System.Activities.ExpressionParser;
    using System.Collections.Generic; 
    using System.Diagnostics.CodeAnalysis;
    using System.Linq.Expressions;
    using System.Reflection;
    using System.Runtime; 
    using System.Collections.ObjectModel;
 
    public static class VisualBasicDesignerHelper 
    {
        static Type VisualBasicExpressionFactoryType = typeof(VisualBasicExpressionFactory<>); 

        // Recompile the VBValue passed in, with its current LocationReferenceEnvironment context
        // in a weakly-typed manner (the argument VBValue's type argument is ignored)
        [SuppressMessage(FxCop.Category.Design, FxCop.Rule.AvoidOutParameters, 
            Justification = "Design has been approved")]
        public static Activity RecompileVisualBasicValue(ActivityWithResult visualBasicValue, 
            out Type returnType, 
            out SourceExpressionException compileError,
            out VisualBasicSettings vbSettings) 
        {
            IVisualBasicExpression ivbv = visualBasicValue as IVisualBasicExpression;
            if (ivbv == null)
            { 
                // the argument must be of type VisualBasicValue<>
                throw FxTrace.Exception.AsError(new ArgumentException()); 
            } 
            string expressionText = ivbv.ExpressionText;
            LocationReferenceEnvironment environment = visualBasicValue.GetParentEnvironment(); 

            HashSet allImportReferences = VisualBasicHelper.GetAllImportReferences(environment != null ? environment.Root : null);

            HashSet namespaces = new HashSet(); 
            HashSet referencedAssemblies = new HashSet();
 
            foreach (VisualBasicImportReference importReference in allImportReferences) 
            {
                namespaces.Add(importReference.Import); 
                referencedAssemblies.Add(importReference.Assembly);
            }

            return CreatePrecompiledVisualBasicValue( 
                null,
                expressionText, 
                namespaces, 
                referencedAssemblies,
                environment, 
                out returnType,
                out compileError,
                out vbSettings);
        } 

        // Recompile the VBReference passed in, with its current LocationReferenceEnvironment context 
        // in a weakly-typed manner (the argument VBReference's type argument is ignored) 
        [SuppressMessage(FxCop.Category.Design, FxCop.Rule.AvoidOutParameters,
            Justification = "Design has been approved")] 
        public static Activity RecompileVisualBasicReference(ActivityWithResult visualBasicReference,
            out Type returnType,
            out SourceExpressionException compileError,
            out VisualBasicSettings vbSettings) 
        {
            IVisualBasicExpression ivbr = visualBasicReference as IVisualBasicExpression; 
            if (ivbr == null) 
            {
                // the argument must be of type VisualBasicReference<> 
                throw FxTrace.Exception.AsError(new ArgumentException());
            }
            string expressionText = ivbr.ExpressionText;
            LocationReferenceEnvironment environment = visualBasicReference.GetParentEnvironment(); 

            HashSet allImportReferences = VisualBasicHelper.GetAllImportReferences(environment != null ? environment.Root : null); 
 
            HashSet namespaces = new HashSet();
            HashSet referencedAssemblies = new HashSet(); 

            foreach (VisualBasicImportReference importReference in allImportReferences)
            {
                namespaces.Add(importReference.Import); 
                referencedAssemblies.Add(importReference.Assembly);
            } 
 
            return CreatePrecompiledVisualBasicReference(
                null, 
                expressionText,
                namespaces,
                referencedAssemblies,
                environment, 
                out returnType,
                out compileError, 
                out vbSettings); 
        }
 
        // create a pre-compiled VBValueExpression, and also provides expressin type back to the caller.
        [SuppressMessage(FxCop.Category.Design, FxCop.Rule.AvoidOutParameters,
            Justification = "Design has been approved")]
        public static Activity CreatePrecompiledVisualBasicValue(Type targetType, string expressionText, IEnumerable namespaces, IEnumerable referencedAssemblies, 
            LocationReferenceEnvironment environment,
            out Type returnType, 
            out SourceExpressionException compileError, 
            out VisualBasicSettings vbSettings)
        { 
            LambdaExpression lambda = null;
            HashSet namespacesSet = new HashSet();
            HashSet assembliesSet = new HashSet();
            compileError = null; 
            returnType = null;
 
            if (namespaces != null) 
            {
                foreach (string ns in namespaces) 
                {
                    if (ns != null)
                    {
                        namespacesSet.Add(ns); 
                    }
                } 
            } 

            if (referencedAssemblies != null) 
            {
                foreach (string assm in referencedAssemblies)
                {
                    if (assm != null) 
                    {
                        assembliesSet.Add(new AssemblyName(assm)); 
                    } 
                }
            } 

            VisualBasicHelper vbhelper = new VisualBasicHelper(expressionText, assembliesSet, namespacesSet);
            if (targetType == null)
            { 
                try
                { 
                    lambda = vbhelper.CompileNonGeneric(environment); 
                    if (lambda != null)
                    { 
                        returnType = lambda.ReturnType;
                    }
                }
                catch (SourceExpressionException e) 
                {
                    compileError = e; 
                    returnType = typeof(object); 
                }
                targetType = returnType; 
            }
            else
            {
                MethodInfo genericCompileMethod = typeof(VisualBasicHelper).GetMethod("Compile", new Type[] { typeof(LocationReferenceEnvironment) }); 
                genericCompileMethod = genericCompileMethod.MakeGenericMethod(new Type[] { targetType });
                try 
                { 
                    lambda = (LambdaExpression)genericCompileMethod.Invoke(vbhelper, new object[] { environment });
                    returnType = targetType; 
                }
                catch (TargetInvocationException e)
                {
                    SourceExpressionException se = e.InnerException as SourceExpressionException; 
                    if (se != null)
                    { 
                        compileError = se; 
                        returnType = typeof(object);
                    } 
                    else
                    {
                        throw FxTrace.Exception.AsError(e.InnerException);
                    } 
                }
            } 
 
            vbSettings = new VisualBasicSettings();
            if (lambda != null) 
            {
                HashSet typeReferences = new HashSet();
                FindTypeReferences(lambda.Body, typeReferences);
                foreach (Type type in typeReferences) 
                {
                    Assembly tassembly = type.Assembly; 
                    if (tassembly.IsDynamic) 
                    {
                        continue; 
                    }
                    string assemblyName = VisualBasicHelper.GetFastAssemblyName(tassembly).Name;
                    VisualBasicImportReference importReference = new VisualBasicImportReference { Assembly = assemblyName, Import = type.Namespace };
                    vbSettings.ImportReferences.Add(importReference); 
                }
            } 
 
            Type concreteHelperType = VisualBasicExpressionFactoryType.MakeGenericType(targetType);
            VisualBasicExpressionFactory expressionFactory = (VisualBasicExpressionFactory)Activator.CreateInstance(concreteHelperType); 

            return expressionFactory.CreateVisualBasicValue(expressionText);
        }
 
        // create a pre-compiled VBValueExpression, and also provides expressin type back to the caller.
        [SuppressMessage(FxCop.Category.Design, FxCop.Rule.AvoidOutParameters, 
            Justification = "Design has been approved")] 
        public static Activity CreatePrecompiledVisualBasicReference(Type targetType, string expressionText, IEnumerable namespaces, IEnumerable referencedAssemblies,
            LocationReferenceEnvironment environment, 
            out Type returnType,
            out SourceExpressionException compileError,
            out VisualBasicSettings vbSettings)
        { 
            LambdaExpression lambda = null;
            HashSet namespacesSet = new HashSet(); 
            HashSet assembliesSet = new HashSet(); 
            compileError = null;
            returnType = null; 

            if (namespaces != null)
            {
                foreach (string ns in namespaces) 
                {
                    if (ns != null) 
                    { 
                        namespacesSet.Add(ns);
                    } 
                }
            }

            if (referencedAssemblies != null) 
            {
                foreach (string assm in referencedAssemblies) 
                { 
                    if (assm != null)
                    { 
                        assembliesSet.Add(new AssemblyName(assm));
                    }
                }
            } 

            VisualBasicHelper vbhelper = new VisualBasicHelper(expressionText, assembliesSet, namespacesSet); 
            if (targetType == null) 
            {
                try 
                {
                    lambda = vbhelper.CompileNonGeneric(environment);
                    if (lambda != null)
                    { 
                        // inspect the expressionTree to see if it is a valid location expression(L-value)
                        string extraErrorMessage; 
                        if (!ExpressionUtilities.IsLocation(lambda, targetType, out extraErrorMessage)) 
                        {
                            string errorMessage = SR.InvalidLValueExpression; 
                            if (extraErrorMessage != null)
                            {
                                errorMessage += ":" + extraErrorMessage;
                            } 
                            throw FxTrace.Exception.AsError(
                                new SourceExpressionException(SR.CompilerErrorSpecificExpression(expressionText, errorMessage))); 
                        } 
                        returnType = lambda.ReturnType;
                    } 
                }
                catch (SourceExpressionException e)
                {
                    compileError = e; 
                    returnType = typeof(object);
                } 
                targetType = returnType; 
            }
            else 
            {
                MethodInfo genericCompileMethod = typeof(VisualBasicHelper).GetMethod("Compile", new Type[] { typeof(LocationReferenceEnvironment) });
                genericCompileMethod = genericCompileMethod.MakeGenericMethod(new Type[] { targetType });
                try 
                {
                    lambda = (LambdaExpression)genericCompileMethod.Invoke(vbhelper, new object[] { environment }); 
                    // inspect the expressionTree to see if it is a valid location expression(L-value) 
                    string extraErrorMessage = null;
                    if (!ExpressionUtilities.IsLocation(lambda, targetType, out extraErrorMessage)) 
                    {
                        string errorMessage = SR.InvalidLValueExpression;
                        if (extraErrorMessage != null)
                        { 
                            errorMessage += ":" + extraErrorMessage;
                        } 
                        throw FxTrace.Exception.AsError( 
                            new SourceExpressionException(SR.CompilerErrorSpecificExpression(expressionText, errorMessage)));
                    } 
                    returnType = targetType;
                }
                catch (SourceExpressionException e)
                { 
                    compileError = e;
                    returnType = typeof(object); 
                } 
                catch (TargetInvocationException e)
                { 
                    SourceExpressionException se = e.InnerException as SourceExpressionException;
                    if (se != null)
                    {
                        compileError = se; 
                        returnType = typeof(object);
                    } 
                    else 
                    {
                        throw FxTrace.Exception.AsError(e.InnerException); 
                    }
                }
            }
 
            vbSettings = new VisualBasicSettings();
            if (lambda != null) 
            { 
                HashSet typeReferences = new HashSet();
                FindTypeReferences(lambda.Body, typeReferences); 
                foreach (Type type in typeReferences)
                {
                    Assembly tassembly = type.Assembly;
                    if (tassembly.IsDynamic) 
                    {
                        continue; 
                    } 
                    string assemblyName = VisualBasicHelper.GetFastAssemblyName(tassembly).Name;
                    VisualBasicImportReference importReference = new VisualBasicImportReference { Assembly = assemblyName, Import = type.Namespace }; 
                    vbSettings.ImportReferences.Add(importReference);
                }
            }
 
            Type concreteHelperType = VisualBasicExpressionFactoryType.MakeGenericType(targetType);
            VisualBasicExpressionFactory expressionFactory = (VisualBasicExpressionFactory)Activator.CreateInstance(concreteHelperType); 
 
            return expressionFactory.CreateVisualBasicReference(expressionText);
        } 

        static void EnsureTypeReferenced(Type type, bool isDirectReference, HashSet typeReferences)
        {
            if (type == null) 
            {
                return; 
            } 

            if (type.HasElementType) 
            {
                EnsureTypeReferenced(type.GetElementType(), isDirectReference, typeReferences);
            }
            else 
            {
                EnsureTypeReferencedRecurse(type, isDirectReference, typeReferences); 
                if (type.IsGenericType) 
                {
                    Type[] typeArgs = type.GetGenericArguments(); 
                    for (int i = 1; i < typeArgs.Length; ++i)
                    {
                        EnsureTypeReferencedRecurse(typeArgs[i], isDirectReference, typeReferences);
                    } 
                }
            } 
        } 

        static void EnsureTypeReferencedRecurse(Type type, bool isDirectReference, HashSet typeReferences) 
        {
            if (typeReferences.Contains(type))
            {
                return; 
            }
 
            // don't add base types/interfaces if they're in the default set (or we'll get superfluous xmlns references) 
            if (isDirectReference || !VisualBasicHelper.DefaultReferencedAssemblies.Contains(type.Assembly))
            { 
                typeReferences.Add(type);
            }

            // make sure any interfaces needed by this type are referenced 
            Type[] interfaces = type.GetInterfaces();
            for (int i = 0; i < interfaces.Length; ++i) 
            { 
                EnsureTypeReferencedRecurse(interfaces[i], false, typeReferences);
            } 

            // same for base types
            Type baseType = type.BaseType;
            while ((baseType != null) && (baseType != TypeHelper.ObjectType)) 
            {
                EnsureTypeReferencedRecurse(baseType, false, typeReferences); 
                baseType = baseType.BaseType; 
            }
        } 

        static void FindTypeReferences(Expression expression, HashSet typeReferences)
        {
            if (expression == null) 
            {
                return; 
            } 
            switch (expression.NodeType)
            { 
                case ExpressionType.Add:
                case ExpressionType.AddChecked:
                case ExpressionType.And:
                case ExpressionType.AndAlso: 
                case ExpressionType.Coalesce:
                case ExpressionType.Divide: 
                case ExpressionType.Equal: 
                case ExpressionType.ExclusiveOr:
                case ExpressionType.GreaterThan: 
                case ExpressionType.GreaterThanOrEqual:
                case ExpressionType.LeftShift:
                case ExpressionType.LessThan:
                case ExpressionType.LessThanOrEqual: 
                case ExpressionType.Modulo:
                case ExpressionType.Multiply: 
                case ExpressionType.MultiplyChecked: 
                case ExpressionType.NotEqual:
                case ExpressionType.Or: 
                case ExpressionType.OrElse:
                case ExpressionType.Power:
                case ExpressionType.RightShift:
                case ExpressionType.Subtract: 
                case ExpressionType.SubtractChecked:
                    BinaryExpression binaryExpression = (BinaryExpression)expression; 
                    FindTypeReferences(binaryExpression.Left, typeReferences); 
                    FindTypeReferences(binaryExpression.Right, typeReferences);
                    return; 

                case ExpressionType.Conditional:
                    ConditionalExpression conditional = (ConditionalExpression)expression;
                    FindTypeReferences(conditional.Test, typeReferences); 
                    FindTypeReferences(conditional.IfTrue, typeReferences);
                    FindTypeReferences(conditional.IfFalse, typeReferences); 
                    return; 

                case ExpressionType.Constant: 
                    ConstantExpression constantExpr = (ConstantExpression)expression;
                    if (constantExpr.Value is Type)
                    {
                        EnsureTypeReferenced((Type)constantExpr.Value, true, typeReferences); 
                    }
                    else if (constantExpr.Value != null) 
                    { 
                        EnsureTypeReferenced(constantExpr.Value.GetType(), true, typeReferences);
                    } 
                    return;

                case ExpressionType.Invoke:
                    InvocationExpression invocation = (InvocationExpression)expression; 
                    FindTypeReferences(invocation.Expression, typeReferences);
                    for (int i = 0; i < invocation.Arguments.Count; i++) 
                    { 
                        FindTypeReferences(invocation.Arguments[i], typeReferences);
                    } 
                    return;

                case ExpressionType.Lambda:
                    LambdaExpression lambda = (LambdaExpression)expression; 
                    FindTypeReferences(lambda.Body, typeReferences);
                    for (int i = 0; i < lambda.Parameters.Count; i++) 
                    { 
                        FindTypeReferences(lambda.Parameters[i], typeReferences);
                    } 
                    return;

                case ExpressionType.ListInit:
                    ListInitExpression listInit = (ListInitExpression)expression; 
                    FindTypeReferences(listInit.NewExpression, typeReferences);
                    for (int i = 0; i < listInit.Initializers.Count; i++) 
                    { 
                        ReadOnlyCollection arguments = listInit.Initializers[i].Arguments;
                        for (int argumentIndex = 0; argumentIndex < arguments.Count; argumentIndex++) 
                        {
                            FindTypeReferences(arguments[argumentIndex], typeReferences);
                        }
                    } 
                    return;
 
                case ExpressionType.Parameter: 
                    ParameterExpression paramExpr = (ParameterExpression)expression;
                    EnsureTypeReferenced(paramExpr.Type, false, typeReferences); 
                    return;

                case ExpressionType.MemberAccess:
                    MemberExpression memberExpression = (MemberExpression)expression; 
                    if (memberExpression.Expression == null)
                    { 
                        EnsureTypeReferenced(memberExpression.Member.DeclaringType, true, typeReferences); 
                    }
                    else 
                    {
                        FindTypeReferences(memberExpression.Expression, typeReferences);
                    }
                    EnsureTypeReferenced(memberExpression.Type, false, typeReferences); 
                    return;
 
                case ExpressionType.MemberInit: 
                    MemberInitExpression memberInit = (MemberInitExpression)expression;
                    FindTypeReferences(memberInit.NewExpression, typeReferences); 
                    ReadOnlyCollection bindings = memberInit.Bindings;
                    for (int i = 0; i < bindings.Count; i++)
                    {
                        FindTypeReferences(bindings[i], typeReferences); 
                    }
                    return; 
 
                case ExpressionType.ArrayIndex:
                    // ArrayIndex can be a MethodCallExpression or a BinaryExpression 
                    MethodCallExpression arrayIndex = expression as MethodCallExpression;
                    if (arrayIndex != null)
                    {
                        FindTypeReferences(arrayIndex.Object, typeReferences); 
                        ReadOnlyCollection arguments = arrayIndex.Arguments;
                        for (int i = 0; i < arguments.Count; i++) 
                        { 
                            FindTypeReferences(arguments[i], typeReferences);
                        } 
                        return;
                    }
                    BinaryExpression alternateIndex = (BinaryExpression)expression;
                    FindTypeReferences(alternateIndex.Left, typeReferences); 
                    FindTypeReferences(alternateIndex.Right, typeReferences);
                    return; 
 
                case ExpressionType.Call:
                    MethodCallExpression methodCall = (MethodCallExpression)expression; 
                    MethodInfo method = methodCall.Method;
                    EnsureTypeReferenced(methodCall.Type, false, typeReferences);
                    if (methodCall.Object != null)
                    { 
                        FindTypeReferences(methodCall.Object, typeReferences);
                    } 
                    else 
                    {
                        EnsureTypeReferenced(method.DeclaringType, true, typeReferences); 
                    }

                    if (method.IsGenericMethod && !method.IsGenericMethodDefinition && !method.ContainsGenericParameters)
                    { 
                        // closed generic method
                        Type[] typeArgs = method.GetGenericArguments(); 
                        for (int i = 1; i < typeArgs.Length; ++i) 
                        {
                            EnsureTypeReferenced(typeArgs[i], true, typeReferences); 
                        }
                    }

                    ParameterInfo[] parameters = method.GetParameters(); 
                    if (parameters != null)
                    { 
                        foreach (ParameterInfo parameter in parameters) 
                        {
                            EnsureTypeReferenced(parameter.ParameterType, false, typeReferences); 
                        }
                    }

                    ReadOnlyCollection callArguments = methodCall.Arguments; 
                    for (int i = 0; i < callArguments.Count; i++)
                    { 
                        FindTypeReferences(callArguments[i], typeReferences); 
                    }
                    return; 

                case ExpressionType.NewArrayInit:
                    NewArrayExpression newArray = (NewArrayExpression)expression;
                    EnsureTypeReferenced(newArray.Type.GetElementType(), true, typeReferences); 
                    ReadOnlyCollection expressions = newArray.Expressions;
                    for (int i = 0; i < expressions.Count; i++) 
                    { 
                        FindTypeReferences(expressions[i], typeReferences);
                    } 
                    return;

                case ExpressionType.NewArrayBounds:
                    NewArrayExpression newArrayBounds = (NewArrayExpression)expression; 
                    EnsureTypeReferenced(newArrayBounds.Type.GetElementType(), true, typeReferences);
                    ReadOnlyCollection boundExpressions = newArrayBounds.Expressions; 
                    for (int i = 0; i < boundExpressions.Count; i++) 
                    {
                        FindTypeReferences(boundExpressions[i], typeReferences); 
                    }
                    return;

                case ExpressionType.New: 
                    NewExpression newExpression = (NewExpression)expression;
                    if (newExpression.Constructor != null) 
                    { 
                        EnsureTypeReferenced(newExpression.Constructor.DeclaringType, true, typeReferences);
                    } 
                    else
                    {
                        // if no constructors defined (e.g. structs), the simply use the type
                        EnsureTypeReferenced(newExpression.Type, true, typeReferences); 
                    }
                    ReadOnlyCollection ctorArguments = newExpression.Arguments; 
                    for (int i = 0; i < ctorArguments.Count; i++) 
                    {
                        FindTypeReferences(ctorArguments[i], typeReferences); 
                    }
                    return;

                case ExpressionType.TypeIs: 
                    TypeBinaryExpression typeBinary = (TypeBinaryExpression)expression;
                    FindTypeReferences(typeBinary.Expression, typeReferences); 
                    EnsureTypeReferenced(typeBinary.TypeOperand, true, typeReferences); 
                    return;
 
                case ExpressionType.TypeAs:
                case ExpressionType.Convert:
                case ExpressionType.ConvertChecked:
                    UnaryExpression unary = (UnaryExpression)expression; 
                    FindTypeReferences(unary.Operand, typeReferences);
                    EnsureTypeReferenced(unary.Type, true, typeReferences); 
                    return; 

                case ExpressionType.ArrayLength: 
                case ExpressionType.Negate:
                case ExpressionType.NegateChecked:
                case ExpressionType.Not:
                case ExpressionType.Quote: 
                case ExpressionType.UnaryPlus:
                    UnaryExpression unaryExpression = (UnaryExpression)expression; 
                    FindTypeReferences(unaryExpression.Operand, typeReferences); 
                    return;
 
                // Expression Tree V2.0 types.  This is due to the hosted VB compiler generating ET V2.0 nodes

                case ExpressionType.Block:
                    BlockExpression block = (BlockExpression)expression; 
                    ReadOnlyCollection variables = block.Variables;
                    for (int i = 0; i < variables.Count; i++) 
                    { 
                        FindTypeReferences(variables[i], typeReferences);
                    } 
                    ReadOnlyCollection blockExpressions = block.Expressions;
                    for (int i = 0; i < blockExpressions.Count; i++)
                    {
                        FindTypeReferences(blockExpressions[i], typeReferences); 
                    }
                    return; 
 
                case ExpressionType.Assign:
                    BinaryExpression assign = (BinaryExpression)expression; 
                    FindTypeReferences(assign.Left, typeReferences);
                    FindTypeReferences(assign.Right, typeReferences);
                    return;
            } 

            Fx.Assert("Don't understand expression type " + expression.NodeType); 
            return; 
        }
 
        static void FindTypeReferences(MemberBinding binding, HashSet typeReferences)
        {
            switch (binding.BindingType)
            { 
                case MemberBindingType.Assignment:
                    MemberAssignment assignment = (MemberAssignment)binding; 
                    FindTypeReferences(assignment.Expression, typeReferences); 
                    return;
 
                case MemberBindingType.ListBinding:
                    MemberListBinding list = (MemberListBinding)binding;
                    ReadOnlyCollection initializers = list.Initializers;
                    for (int i = 0; i < initializers.Count; i++) 
                    {
                        ReadOnlyCollection arguments = initializers[i].Arguments; 
                        for (int j = 0; j < arguments.Count; j++) 
                        {
                            FindTypeReferences(arguments[j], typeReferences); 
                        }
                    }
                    return;
 
                case MemberBindingType.MemberBinding:
                    MemberMemberBinding member = (MemberMemberBinding)binding; 
                    ReadOnlyCollection bindings = member.Bindings; 
                    for (int i = 0; i < bindings.Count; i++)
                    { 
                        FindTypeReferences(bindings[i], typeReferences);
                    }
                    return;
 
                default:
                    Fx.Assert("MemberBinding type '" + binding.BindingType + "' is not supported."); 
                    return; 
            }
        } 

        // to perform the generics dance around VisualBasicValue/Reference we need these helpers
        abstract class VisualBasicExpressionFactory
        { 
            public abstract Activity CreateVisualBasicValue(string expressionText);
            public abstract Activity CreateVisualBasicReference(string expressionText); 
        } 

        class VisualBasicExpressionFactory : VisualBasicExpressionFactory 
        {
            public override Activity CreateVisualBasicReference(string expressionText)
            {
                return new VisualBasicReference() 
                {
                    ExpressionText = expressionText 
                }; 
            }
 
            public override Activity CreateVisualBasicValue(string expressionText)
            {
                return new VisualBasicValue()
                { 
                    ExpressionText = expressionText
                }; 
            } 
        }
    } 
}

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

Link Menu

Network programming in C#, Network Programming in VB.NET, Network Programming in .NET
This book is available now!
Buy at Amazon US or
Buy at Amazon UK