WorkflowDataContext.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 / WorkflowDataContext.cs / 1305376 / WorkflowDataContext.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// Copyright (c) Microsoft Corporation.  All rights reserved.
//-----------------------------------------------------------------------------

namespace System.Activities 
{
    using System; 
    using System.Activities.Hosting; 
    using System.Activities.Runtime;
    using System.Collections.Generic; 
    using System.ComponentModel;
    using System.Runtime;

    [Fx.Tag.XamlVisible(false)] 
    public sealed class WorkflowDataContext : CustomTypeDescriptor, INotifyPropertyChanged, IDisposable
    { 
        ActivityExecutor executor; 
        ActivityInstance activityInstance;
        IDictionary locationMapping; 
        PropertyChangedEventHandler propertyChangedEventHandler;
        PropertyDescriptorCollection properties;
        ActivityContext cachedResolutionContext;
 
        internal WorkflowDataContext(ActivityExecutor executor, ActivityInstance activityInstance)
        { 
            this.executor = executor; 
            this.activityInstance = activityInstance;
            this.properties = CreateProperties(); 
        }

        public event PropertyChangedEventHandler PropertyChanged;
 
        // We want our own cached ActivityContext rather than using this.executor.GetResolutionContext
        // because there is no synchronization of access to the executor's cached object and access thru 
        // this WorkflowDataContext will not be done on the workflow runtime thread. 
        ActivityContext ResolutionContext
        { 
            get
            {
                if (this.cachedResolutionContext == null)
                { 
                    this.cachedResolutionContext = new ActivityContext(this.activityInstance, this.executor);
                    this.cachedResolutionContext.AllowChainedEnvironmentAccess = true; 
                } 
                else
                { 
                    this.cachedResolutionContext.Reinitialize(this.activityInstance, this.executor);
                }
                return this.cachedResolutionContext;
            } 
        }
 
        PropertyChangedEventHandler PropertyChangedEventHandler 
        {
            get 
            {
                if (this.propertyChangedEventHandler == null)
                {
                    this.propertyChangedEventHandler = new PropertyChangedEventHandler(this.OnLocationChanged); 
                }
                return this.propertyChangedEventHandler; 
            } 
        }
 
        PropertyDescriptorCollection CreateProperties()
        {
            // The name in child Activity will shadow the name in parent.
            Dictionary names = new Dictionary(); 

            List propertyList = new List(); 
 
            LocationReferenceEnvironment environment = this.activityInstance.Activity.PublicEnvironment;
            while (environment != null) 
            {
                foreach (LocationReference locRef in environment.GetLocationReferences())
                {
                    AddProperty(locRef, names, propertyList); 
                }
 
                environment = environment.Parent; 

            } 

            return new PropertyDescriptorCollection(propertyList.ToArray(), true);
        }
 
        void AddProperty(LocationReference reference, Dictionary names,
            List propertyList) 
        { 
            if (!string.IsNullOrEmpty(reference.Name) &&
                !names.ContainsKey(reference.Name)) 
            {
                names.Add(reference.Name, reference);
                PropertyDescriptorImpl property = new PropertyDescriptorImpl(reference);
                propertyList.Add(property); 
                AddNotifyHandler(property);
            } 
        } 

        void AddNotifyHandler(PropertyDescriptorImpl property) 
        {
            ActivityContext activityContext = this.ResolutionContext;
            try
            { 
                Location location = property.LocationReference.GetLocation(activityContext);
                INotifyPropertyChanged notify = location as INotifyPropertyChanged; 
                if (notify != null) 
                {
                    notify.PropertyChanged += PropertyChangedEventHandler; 

                    if (this.locationMapping == null)
                    {
                        this.locationMapping = new Dictionary(); 
                    }
                    this.locationMapping.Add(location, property); 
                } 
            }
            finally 
            {
                activityContext.Dispose();
            }
        } 

        void OnLocationChanged(object sender, PropertyChangedEventArgs e) 
        { 
            PropertyChangedEventHandler handler = this.PropertyChanged;
            if (handler != null) 
            {
                Location location = (Location)sender;

                Fx.Assert(this.locationMapping != null, "Location mapping must not be null."); 
                PropertyDescriptorImpl property;
                if (this.locationMapping.TryGetValue(location, out property)) 
                { 
                    if (e.PropertyName == "Value")
                    { 
                        handler(this, new PropertyChangedEventArgs(property.Name));
                    }
                    else
                    { 
                        handler(this, new PropertyChangedEventArgs(property.Name + "." + e.PropertyName));
                    } 
                } 
            }
        } 

        public void Dispose()
        {
            if (this.locationMapping != null) 
            {
                foreach (KeyValuePair pair in this.locationMapping) 
                { 
                    INotifyPropertyChanged notify = pair.Value as INotifyPropertyChanged;
                    if (notify != null) 
                    {
                        notify.PropertyChanged -= PropertyChangedEventHandler;
                    }
                } 
            }
        } 
 
        public override PropertyDescriptorCollection GetProperties()
        { 
            return this.properties;
        }

        class PropertyDescriptorImpl : PropertyDescriptor 
        {
            LocationReference reference; 
            // 

 

            public PropertyDescriptorImpl(LocationReference reference)
                : base(reference.Name, new Attribute[0])
            { 
                this.reference = reference;
            } 
 
            public override Type ComponentType
            { 
                get { return typeof(WorkflowDataContext); }
            }

            public override bool IsReadOnly 
            {
                get 
                { 
                    //
 
                    return false;
                }
            }
 
            public override Type PropertyType
            { 
                get 
                {
                    return this.reference.Type; 
                }
            }

            public LocationReference LocationReference 
            {
                get 
                { 
                    return this.reference;
                } 
            }

            public override bool CanResetValue(object component)
            { 
                return false;
            } 
 
            public override object GetValue(object component)
            { 
                WorkflowDataContext dataContext = (WorkflowDataContext)component;

                ActivityContext activityContext = dataContext.ResolutionContext;
                try 
                {
                    return this.reference.GetLocation(activityContext).Value; 
                } 
                finally
                { 
                    activityContext.Dispose();
                }
            }
 
            public override void ResetValue(object component)
            { 
                throw FxTrace.Exception.AsError(new NotSupportedException(SR.CannotResetPropertyInDataContext)); 
            }
 
            public override void SetValue(object component, object value)
            {
                if (IsReadOnly)
                { 
                    throw FxTrace.Exception.AsError(new NotSupportedException(SR.PropertyReadOnlyInWorkflowDataContext(this.Name)));
                } 
 
                WorkflowDataContext dataContext = (WorkflowDataContext)component;
 
                ActivityContext activityContext = dataContext.ResolutionContext;
                try
                {
                    Location location = this.reference.GetLocation(activityContext); 
                    location.Value = value;
                } 
                finally 
                {
                    activityContext.Dispose(); 
                }
            }

            public override bool ShouldSerializeValue(object component) 
            {
                return true; 
            } 
        }
    } 
}

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

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