82 lines
2.8 KiB
C#
82 lines
2.8 KiB
C#
//----------------------------------------------------------------
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// Copyright (c) Microsoft Corporation. All rights reserved.
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//----------------------------------------------------------------
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namespace System.Activities.Expressions
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{
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using System.Activities;
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using System.Activities.Validation;
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using System.ComponentModel;
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using System.Reflection;
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public sealed class FieldValue<TOperand, TResult> : CodeActivity<TResult>
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{
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Func<TOperand, TResult> operationFunction;
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bool isOperationFunctionStatic;
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[DefaultValue(null)]
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public string FieldName
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{
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get;
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set;
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}
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[DefaultValue(null)]
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public InArgument<TOperand> Operand
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{
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get;
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set;
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}
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protected override void CacheMetadata(CodeActivityMetadata metadata)
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{
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bool isRequired = false;
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if (typeof(TOperand).IsEnum)
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{
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metadata.AddValidationError(SR.TargetTypeCannotBeEnum(this.GetType().Name, this.DisplayName));
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}
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if (string.IsNullOrEmpty(this.FieldName))
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{
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metadata.AddValidationError(SR.ActivityPropertyMustBeSet("FieldName", this.DisplayName));
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}
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else
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{
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FieldInfo fieldInfo = null;
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Type operandType = typeof(TOperand);
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fieldInfo = operandType.GetField(this.FieldName);
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if (fieldInfo == null)
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{
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metadata.AddValidationError(SR.MemberNotFound(this.FieldName, typeof(TOperand).Name));
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}
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else
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{
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this.isOperationFunctionStatic = fieldInfo.IsStatic;
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isRequired = !this.isOperationFunctionStatic;
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ValidationError validationError;
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if (!MemberExpressionHelper.TryGenerateLinqDelegate(this.FieldName, true, this.isOperationFunctionStatic, out this.operationFunction, out validationError))
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{
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metadata.AddValidationError(validationError);
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}
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}
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}
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MemberExpressionHelper.AddOperandArgument(metadata, this.Operand, isRequired);
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}
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protected override TResult Execute(CodeActivityContext context)
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{
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TOperand operandValue = this.Operand.Get(context);
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if (!this.isOperationFunctionStatic && operandValue == null)
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{
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throw FxTrace.Exception.AsError(new InvalidOperationException(SR.MemberCannotBeNull("Operand", this.GetType().Name, this.DisplayName)));
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}
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return this.operationFunction(operandValue);
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}
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}
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}
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