91 lines
2.1 KiB
C#
91 lines
2.1 KiB
C#
/*
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* Copyright (c) 2023 ETH Zürich, Educational Development and Technology (LET)
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*/
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using System;
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using SafeExamBrowser.Core.Contracts.OperationModel;
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using SafeExamBrowser.Core.Contracts.OperationModel.Events;
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namespace SafeExamBrowser.Core.Operations
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{
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/// <summary>
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/// A wrapper operation to allow for a lazy (just-in-time) instantiation of an operation, initialized on <see cref="Perform"/>.
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/// Is useful when e.g. dependencies for a certain operation are not available during execution of the composition root, but rather
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/// only after a preceding operation within an <see cref="IOperationSequence"/> has finished.
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/// </summary>
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public class LazyInitializationOperation : IOperation
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{
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private Func<IOperation> initialize;
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private IOperation operation;
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private event ActionRequiredEventHandler ActionRequiredImpl;
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private event StatusChangedEventHandler StatusChangedImpl;
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public event ActionRequiredEventHandler ActionRequired
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{
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add
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{
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ActionRequiredImpl += value;
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if (operation != null)
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{
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operation.ActionRequired += value;
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}
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}
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remove
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{
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ActionRequiredImpl -= value;
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if (operation != null)
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{
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operation.ActionRequired -= value;
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}
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}
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}
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public event StatusChangedEventHandler StatusChanged
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{
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add
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{
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StatusChangedImpl += value;
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if (operation != null)
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{
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operation.StatusChanged += value;
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}
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}
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remove
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{
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StatusChangedImpl -= value;
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if (operation != null)
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{
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operation.StatusChanged -= value;
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}
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}
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}
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public LazyInitializationOperation(Func<IOperation> initialize)
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{
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this.initialize = initialize;
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}
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public OperationResult Perform()
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{
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operation = initialize.Invoke();
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operation.ActionRequired += ActionRequiredImpl;
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operation.StatusChanged += StatusChangedImpl;
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return operation.Perform();
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}
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public OperationResult Revert()
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{
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return operation.Revert();
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}
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}
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}
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