75 lines
3.2 KiB
C#
75 lines
3.2 KiB
C#
namespace Caliburn.Micro.Core {
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using System;
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/// <summary>
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/// A result decorator which rescues errors from the decorated result by executing a rescue coroutine.
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/// </summary>
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/// <typeparam name="TException">The type of the exception we want to perform the rescue on</typeparam>
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public class RescueResultDecorator<TException> : ResultDecoratorBase where TException : Exception {
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static readonly ILog Log = LogManager.GetLog(typeof(RescueResultDecorator<>));
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readonly bool cancelResult;
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readonly Func<TException, IResult> coroutine;
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/// <summary>
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/// Initializes a new instance of the <see cref="RescueResultDecorator<TException>"/> class.
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/// </summary>
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/// <param name="result">The result to decorate.</param>
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/// <param name="coroutine">The rescue coroutine.</param>
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/// <param name="cancelResult">Set to true to cancel the result after executing rescue.</param>
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public RescueResultDecorator(IResult result, Func<TException, IResult> coroutine, bool cancelResult = true) : base(result) {
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if (coroutine == null)
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throw new ArgumentNullException("coroutine");
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this.coroutine = coroutine;
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this.cancelResult = cancelResult;
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}
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/// <summary>
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/// Called when the execution of the decorated result has completed.
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/// </summary>
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/// <param name="context">The context.</param>
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/// <param name="innerResult">The decorated result.</param>
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/// <param name="args">The <see cref="ResultCompletionEventArgs" /> instance containing the event data.</param>
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protected override void OnInnerResultCompleted(CoroutineExecutionContext context, IResult innerResult, ResultCompletionEventArgs args) {
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var error = args.Error as TException;
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if (error == null) {
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OnCompleted(args);
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}
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else {
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Log.Error(error);
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Log.Info(string.Format("Executing coroutine because {0} threw an exception.", innerResult.GetType().Name));
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Rescue(context, error);
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}
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}
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void Rescue(CoroutineExecutionContext context, TException exception) {
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IResult rescueResult;
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try {
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rescueResult = coroutine(exception);
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}
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catch (Exception ex) {
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OnCompleted(new ResultCompletionEventArgs {Error = ex});
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return;
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}
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try {
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rescueResult.Completed += RescueCompleted;
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IoC.BuildUp(rescueResult);
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rescueResult.Execute(context);
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}
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catch (Exception ex) {
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RescueCompleted(rescueResult, new ResultCompletionEventArgs {Error = ex});
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}
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}
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void RescueCompleted(object sender, ResultCompletionEventArgs args) {
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((IResult)sender).Completed -= RescueCompleted;
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OnCompleted(new ResultCompletionEventArgs
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{
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Error = args.Error,
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WasCancelled = (args.Error == null && (args.WasCancelled || cancelResult))
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});
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}
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}
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}
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