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//----------------------------------------------------------------
// Copyright (c) Microsoft Corporation. All rights reserved.
//----------------------------------------------------------------
namespace System.Activities.Expressions
{
using System.Activities;
using System.Activities.Statements;
using System.Linq.Expressions;
using System.Activities.Validation;
using System.Collections.Generic;
using System.ComponentModel;
using System.Runtime;
public sealed class Equal<TLeft, TRight, TResult> : CodeActivity<TResult>
{
//Lock is not needed for operationFunction here. The reason is that delegates for a given Equal<TLeft, TRight, TResult> are the same.
//It's possible that 2 threads are assigning the operationFucntion at the same time. But it's okay because the compiled codes are the same.
static Func<TLeft, TRight, TResult> operationFunction;
[RequiredArgument]
[DefaultValue(null)]
public InArgument<TLeft> Left
{
get;
set;
}
[RequiredArgument]
[DefaultValue(null)]
public InArgument<TRight> Right
{
get;
set;
}
protected override void CacheMetadata(CodeActivityMetadata metadata)
{
BinaryExpressionHelper.OnGetArguments(metadata, this.Left, this.Right);
if (operationFunction == null)
{
ValidationError validationError;
if (!BinaryExpressionHelper.TryGenerateLinqDelegate(ExpressionType.Equal, out operationFunction, out validationError))
{
metadata.AddValidationError(validationError);
}
}
}
protected override TResult Execute(CodeActivityContext context)
{
Fx.Assert(operationFunction != null, "OperationFunction must exist.");
TLeft leftValue = this.Left.Get(context);
TRight rightValue = this.Right.Get(context);
return operationFunction(leftValue, rightValue);
}
}
}
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