ActivityWithResultConverter.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / ndp / cdf / src / NetFx40 / System.Activities / System / Activities / XamlIntegration / ActivityWithResultConverter.cs / 1305376 / ActivityWithResultConverter.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace System.Activities.XamlIntegration 
{
    using Microsoft.VisualBasic.Activities; 
    using System; 
    using System.Activities.Expressions;
    using System.Collections.Generic; 
    using System.ComponentModel;
    using System.Linq;
    using System.Reflection;
    using System.Runtime; 
    using System.Text.RegularExpressions;
    using System.Windows.Markup; 
    using System.Xaml; 
    using System.Xaml.Schema;
    using System.Xml.Linq; 
    using Microsoft.VisualBasic.Activities.XamlIntegration;

    public sealed class ActivityWithResultConverter : TypeConverterBase
    { 
        public ActivityWithResultConverter()
            : base(typeof(Activity<>), typeof(ExpressionConverterHelper<>)) 
        { 
        }
 
        public ActivityWithResultConverter(Type type)
            : base(type, typeof(Activity<>), typeof(ExpressionConverterHelper<>))
        {
        } 

        internal static object GetRootTemplatedActivity(IServiceProvider serviceProvider) 
        { 
            // For now, we only support references to the root Activity when we're inside an Activity.Body
            // Note that in the case of nested activity bodies, this gives us the outer activity 
            IRootObjectProvider rootProvider =
                serviceProvider.GetService(typeof(IRootObjectProvider)) as IRootObjectProvider;
            if (rootProvider == null)
            { 
                return null;
            } 
            IAmbientProvider ambientProvider = 
                serviceProvider.GetService(typeof(IAmbientProvider)) as IAmbientProvider;
            if (ambientProvider == null) 
            {
                return null;
            }
            IXamlSchemaContextProvider schemaContextProvider = 
                serviceProvider.GetService(typeof(IXamlSchemaContextProvider)) as IXamlSchemaContextProvider;
            if (schemaContextProvider == null) 
            { 
                return null;
            } 
            XamlMember activityBody = GetXamlMember(schemaContextProvider.SchemaContext, typeof(Activity), "Implementation");
            XamlMember dynamicActivityBody = GetXamlMember(schemaContextProvider.SchemaContext, typeof(DynamicActivity), "Implementation");
            if (activityBody == null || dynamicActivityBody == null)
            { 
                return null;
            } 
            if (ambientProvider.GetFirstAmbientValue(null, activityBody, dynamicActivityBody) == null) 
            {
                return null; 
            }
            object rootActivity = rootProvider.RootObject as Activity;
            return rootActivity;
        } 

        static XamlMember GetXamlMember(XamlSchemaContext schemaContext, Type type, string memberName) 
        { 
            XamlType xamlType = schemaContext.GetXamlType(type);
            if (xamlType == null) 
            {
                return null;
            }
            XamlMember xamlMember = xamlType.GetMember(memberName); 
            return xamlMember;
        } 
 
        internal sealed class ExpressionConverterHelper : TypeConverterHelper>
        { 
            static Regex LiteralEscapeRegex = new Regex(@"^(%+\[)");
            static Type LocationHelperType = typeof(LocationHelper<>);

            TypeConverter baseConverter; 
            Type valueType;
            LocationHelper locationHelper; // true if we're dealing with a Location 
 
            public ExpressionConverterHelper()
                : this(TypeHelper.AreTypesCompatible(typeof(T), typeof(Location))) 
            {
            }

            public ExpressionConverterHelper(bool isLocationType) 
            {
                this.valueType = typeof(T); 
 
                if (isLocationType)
                { 
                    Fx.Assert(this.valueType.IsGenericType && this.valueType.GetGenericArguments().Length == 1, "Should only get Location here");
                    this.valueType = this.valueType.GetGenericArguments()[0];
                    Type concreteHelperType = LocationHelperType.MakeGenericType(typeof(T), this.valueType);
                    this.locationHelper = (LocationHelper)Activator.CreateInstance(concreteHelperType); 
                }
            } 
 
            TypeConverter BaseConverter
            { 
                get
                {
                    if (this.baseConverter == null)
                    { 
                        this.baseConverter = TypeDescriptor.GetConverter(this.valueType);
                    } 
 
                    return this.baseConverter;
                } 
            }

            public override Activity ConvertFromString(string text, ITypeDescriptorContext context)
            { 
                if (IsExpression(text))
                { 
                    // Expression.  Use the expression parser. 
                    string expressionText = text.Substring(1, text.Length - 2);
 
                    if (this.locationHelper != null)
                    {
                        //
                        return (Activity)this.locationHelper.CreateExpression(expressionText); 
                    }
                    else 
                    { 
                        //
                        return new VisualBasicValue() 
                        {
                            ExpressionText = expressionText
                        };
                    } 
                }
                else 
                { 
                    if (this.locationHelper != null)
                    { 
                        throw FxTrace.Exception.AsError(new InvalidOperationException(SR.InvalidLocationExpression));
                    }

                    // look for "%[....]" escape pattern 
                    if (text.EndsWith("]", StringComparison.Ordinal) && LiteralEscapeRegex.IsMatch(text))
                    { 
                        // strip off the very front-most '%' from the original string 
                        text = text.Substring(1, text.Length - 1);
                    } 

                    T literalValue;
                    if (text is T)
                    { 
                        literalValue = (T)(object)text;
                    } 
                    else if (text == string.Empty) // workaround for System.Runtime.Xaml bug 
                    {
                        literalValue = default(T); 
                    }
                    else
                    {
                        // Literal value.  Invoke the base type converter. 
                        literalValue = (T)BaseConverter.ConvertFromString(context, text);
                    } 
 
                    return new Literal { Value = literalValue };
                } 
            }

            static bool IsExpression(string text)
            { 
                return (text.StartsWith("[", StringComparison.Ordinal) && text.EndsWith("]", StringComparison.Ordinal));
            } 
 
            // to perform the generics dance around Locations we need these helpers
            abstract class LocationHelper 
            {
                public abstract Activity CreateExpression(string expressionText);
            }
 
            class LocationHelper : LocationHelper
            { 
                public override Activity CreateExpression(string expressionText) 
                {
                    return new VisualBasicReference() 
                    {
                        ExpressionText = expressionText
                    };
                } 
            }
        } 
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
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ActivityWithResultConverter.cs source code in C# .NET

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