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//-----------------------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//-----------------------------------------------------------------------------
namespace Microsoft.VisualBasic.Activities
{
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Activities;
using System.Activities.Expressions;
using System.Activities.ExpressionParser;
using System.Activities.XamlIntegration;
using System.Linq.Expressions;
using System.Windows.Markup;
using System.ComponentModel;
using System.Runtime;
[DebuggerStepThrough]
public sealed class VisualBasicValue<TResult> : CodeActivity<TResult>, IValueSerializableExpression, IExpressionContainer, ITextExpression
{
Expression<Func<ActivityContext, TResult>> expressionTree;
Func<ActivityContext, TResult> compiledExpression;
CompiledExpressionInvoker invoker;
public VisualBasicValue()
: base()
{
this.UseOldFastPath = true;
}
public VisualBasicValue(string expressionText)
: this()
{
this.ExpressionText = expressionText;
}
public string ExpressionText
{
get;
set;
}
[DesignerSerializationVisibility(DesignerSerializationVisibility.Hidden)]
public string Language
{
get
{
return VisualBasicHelper.Language;
}
}
public bool RequiresCompilation
{
get
{
return false;
}
}
protected override TResult Execute(CodeActivityContext context)
{
if (!this.invoker.IsStaticallyCompiled)
{
if (this.expressionTree != null)
{
if (this.compiledExpression == null)
{
this.compiledExpression = this.expressionTree.Compile();
}
return this.compiledExpression(context);
}
else
{
return default(TResult);
}
}
else
{
return (TResult)this.invoker.InvokeExpression(context);
}
}
protected override void CacheMetadata(CodeActivityMetadata metadata)
{
this.expressionTree = null;
this.invoker = new CompiledExpressionInvoker(this, false, metadata);
if (this.invoker.IsStaticallyCompiled == true)
{
return;
}
// If ICER is not implemented that means we haven't been compiled
CodeActivityPublicEnvironmentAccessor publicAccessor = CodeActivityPublicEnvironmentAccessor.Create(metadata);
try
{
this.expressionTree = VisualBasicHelper.Compile<TResult>(this.ExpressionText, publicAccessor, false);
}
catch (SourceExpressionException e)
{
metadata.AddValidationError(e.Message);
}
}
public bool CanConvertToString(IValueSerializerContext context)
{
// we can always convert to a string
return true;
}
public string ConvertToString(IValueSerializerContext context)
{
// Return our bracket-escaped text
return "[" + this.ExpressionText + "]";
}
public Expression GetExpressionTree()
{
if (this.IsMetadataCached)
{
if (this.expressionTree == null)
{
// it's safe to create this CodeActivityMetadata here,
// because we know we are using it only as lookup purpose.
CodeActivityMetadata metadata = new CodeActivityMetadata(this, this.GetParentEnvironment(), false);
CodeActivityPublicEnvironmentAccessor publicAccessor = CodeActivityPublicEnvironmentAccessor.CreateWithoutArgument(metadata);
try
{
this.expressionTree = VisualBasicHelper.Compile<TResult>(this.ExpressionText, publicAccessor, false);
}
catch (SourceExpressionException e)
{
throw FxTrace.Exception.AsError(new InvalidOperationException(SR.VBExpressionTamperedSinceLastCompiled(e.Message)));
}
finally
{
metadata.Dispose();
}
}
Fx.Assert(this.expressionTree.NodeType == ExpressionType.Lambda, "Lambda expression required");
return ExpressionUtilities.RewriteNonCompiledExpressionTree((LambdaExpression)this.expressionTree);
}
else
{
throw FxTrace.Exception.AsError(new InvalidOperationException(SR.ActivityIsUncached));
}
}
}
}
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