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//-----------------------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
namespace System.Activities.Statements
{
using System.Activities;
using System.Activities.Validation;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Runtime.Collections;
using System.Windows.Markup;
[ContentProperty("Activities")]
public sealed class Sequence : NativeActivity
{
Collection<Activity> activities;
Collection<Variable> variables;
Variable<int> lastIndexHint;
CompletionCallback onChildComplete;
public Sequence()
: base()
{
this.lastIndexHint = new Variable<int>();
this.onChildComplete = new CompletionCallback(InternalExecute);
}
public Collection<Variable> Variables
{
get
{
if (this.variables == null)
{
this.variables = new ValidatingCollection<Variable>
{
// disallow null values
OnAddValidationCallback = item =>
{
if (item == null)
{
throw FxTrace.Exception.ArgumentNull("item");
}
}
};
}
return this.variables;
}
}
[DependsOn("Variables")]
public Collection<Activity> Activities
{
get
{
if (this.activities == null)
{
this.activities = new ValidatingCollection<Activity>
{
// disallow null values
OnAddValidationCallback = item =>
{
if (item == null)
{
throw FxTrace.Exception.ArgumentNull("item");
}
}
};
}
return this.activities;
}
}
protected override void OnCreateDynamicUpdateMap(DynamicUpdate.NativeActivityUpdateMapMetadata metadata, Activity originalActivity)
{
// Our algorithm for recovering from update depends on iterating a unique Activities list.
// So we can't support update if the same activity is referenced more than once.
for (int i = 0; i < this.Activities.Count - 1; i++)
{
for (int j = i + 1; j < this.Activities.Count; j++)
{
if (this.Activities[i] == this.Activities[j])
{
metadata.DisallowUpdateInsideThisActivity(SR.SequenceDuplicateReferences);
break;
}
}
}
}
protected override void CacheMetadata(NativeActivityMetadata metadata)
{
metadata.SetChildrenCollection(this.Activities);
metadata.SetVariablesCollection(this.Variables);
metadata.AddImplementationVariable(this.lastIndexHint);
}
protected override void Execute(NativeActivityContext context)
{
if (this.activities != null && this.Activities.Count > 0)
{
Activity nextChild = this.Activities[0];
context.ScheduleActivity(nextChild, this.onChildComplete);
}
}
void InternalExecute(NativeActivityContext context, ActivityInstance completedInstance)
{
int completedInstanceIndex = this.lastIndexHint.Get(context);
if (completedInstanceIndex >= this.Activities.Count || this.Activities[completedInstanceIndex] != completedInstance.Activity)
{
completedInstanceIndex = this.Activities.IndexOf(completedInstance.Activity);
}
int nextChildIndex = completedInstanceIndex + 1;
if (nextChildIndex == this.Activities.Count)
{
return;
}
Activity nextChild = this.Activities[nextChildIndex];
context.ScheduleActivity(nextChild, this.onChildComplete);
this.lastIndexHint.Set(context, nextChildIndex);
}
}
}
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