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using System;
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using System.Diagnostics;
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namespace Implab {
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/// <summary>
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/// Класс для асинхронного получения результатов. Так называемое "обещание".
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/// </summary>
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/// <typeparam name="T">Тип получаемого результата</typeparam>
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/// <remarks>
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/// <para>Сервис при обращении к его методу дает обещаиние о выполнении операции,
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/// клиент получив такое обещание может установить ряд обратных вызово для получения
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/// событий выполнения обещания, тоесть завершения операции и предоставлении результатов.</para>
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/// <para>
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/// Обещение может быть как выполнено, так и выполнено с ошибкой. Для подписки на
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/// данные события клиент должен использовать методы <c>Then</c>.
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/// </para>
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/// <para>
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/// Сервис, в свою очередь, по окончанию выполнения операции (возможно с ошибкой),
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/// использует методы <c>Resolve</c> либо <c>Reject</c> для оповещения клиетна о
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/// выполнении обещания.
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/// </para>
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/// <para>
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/// Если сервер успел выполнить обещание еще до того, как клиент на него подписался,
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/// то в момент подписки клиента будут вызваны соответсвующие события в синхронном
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/// режиме и клиент будет оповещен в любом случае. Иначе, обработчики добавляются в
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/// список в порядке подписания и в этом же порядке они будут вызваны при выполнении
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/// обещания.
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/// </para>
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/// <para>
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/// Обрабатывая результаты обещания можно преобразовывать результаты либо инициировать
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/// связанные асинхронные операции, которые также возвращают обещания. Для этого следует
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/// использовать соответствующую форму методе <c>Then</c>.
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/// </para>
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/// <para>
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/// Также хорошим правилом является то, что <c>Resolve</c> и <c>Reject</c> должен вызывать
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/// только инициатор обещания иначе могут возникнуть противоречия.
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/// </para>
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/// </remarks>
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public class Promise<T> : AbstractPromise<IDeferred<T>>, IPromise<T>, IDeferred<T> {
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class StubDeferred : IDeferred, IDeferred<T> {
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public static readonly StubDeferred instance = new StubDeferred();
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StubDeferred() {
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}
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#region IDeferred implementation
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public void Resolve(T value) {
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}
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public void Resolve() {
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}
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public void Reject(Exception error) {
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}
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#endregion
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#region ICancellable implementation
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public void Cancel() {
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}
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public void Cancel(Exception reason) {
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}
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#endregion
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}
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class RemapDescriptor<T2> : IDeferred<T> {
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readonly Func<T,T2> m_remap;
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readonly Func<Exception, T2> m_failed;
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readonly Func<Exception, T2> m_cancel;
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readonly IDeferred<T2> m_deferred;
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public RemapDescriptor(Func<T,T2> remap, Func<Exception,T2> failed, Func<Exception, T2> cancel, IDeferred<T2> deferred ) {
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Debug.Assert(deferred != null);
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m_remap = remap;
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m_failed = failed;
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m_cancel = cancel;
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m_deferred = deferred;
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}
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#region IDeferred implementation
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public void Resolve(T value) {
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if (m_remap != null) {
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try {
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m_deferred.Resolve(m_remap(value));
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} catch (Exception ex) {
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Reject(ex);
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}
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}
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}
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public void Reject(Exception error) {
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if (m_failed != null) {
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try {
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m_deferred.Resolve(m_failed(error));
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} catch (Exception ex) {
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m_deferred.Reject(ex);
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}
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} else {
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m_deferred.Reject(error);
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}
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}
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#endregion
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#region ICancellable implementation
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public void Cancel(Exception reason) {
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if (m_cancel != null) {
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try {
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m_deferred.Resolve(m_cancel(reason));
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} catch (Exception ex) {
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Reject(ex);
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}
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} else {
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m_deferred.Cancel(reason);
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}
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}
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public void Cancel() {
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Cancel(null);
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}
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#endregion
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}
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class ListenerDescriptor : IDeferred<T> {
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readonly Action m_handler;
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readonly PromiseEventType m_events;
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public ListenerDescriptor(Action handler, PromiseEventType events) {
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Debug.Assert(handler != null);
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m_handler = handler;
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m_events = events;
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}
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#region IDeferred implementation
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public void Resolve(T value) {
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if (m_events.HasFlag(PromiseEventType.Success)) {
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try {
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m_handler();
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// Analysis disable once EmptyGeneralCatchClause
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} catch {
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}
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}
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}
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public void Reject(Exception error) {
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if (m_events.HasFlag(PromiseEventType.Error)){
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try {
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m_handler();
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// Analysis disable once EmptyGeneralCatchClause
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} catch {
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}
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}
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}
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#endregion
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#region ICancellable implementation
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public void Cancel() {
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Cancel(null);
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}
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public void Cancel(Exception reason) {
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if (m_events.HasFlag(PromiseEventType.Cancelled)){
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try {
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m_handler();
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// Analysis disable once EmptyGeneralCatchClause
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} catch {
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}
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}
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}
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#endregion
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}
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class ValueEventDescriptor : IDeferred<T> {
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readonly Action<T> m_success;
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readonly Action<Exception> m_failed;
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readonly Action<Exception> m_cancelled;
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readonly IDeferred<T> m_deferred;
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public ValueEventDescriptor(Action<T> success, Action<Exception> failed, Action<Exception> cancelled, IDeferred<T> deferred) {
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Debug.Assert(deferred != null);
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m_success = success;
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m_failed = failed;
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m_cancelled = cancelled;
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m_deferred = deferred;
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}
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#region IDeferred implementation
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public void Resolve(T value) {
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if (m_success != null) {
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try {
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m_success(value);
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m_deferred.Resolve(value);
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} catch (Exception ex) {
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Reject(ex);
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}
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}
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}
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public void Reject(Exception error) {
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if (m_failed != null) {
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try {
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m_failed(error);
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m_deferred.Resolve(default(T));
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} catch(Exception ex) {
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m_deferred.Reject(ex);
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}
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} else {
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m_deferred.Reject(error);
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}
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}
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#endregion
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#region ICancellable implementation
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public void Cancel(Exception reason) {
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if (m_cancelled != null) {
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try {
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m_cancelled(reason);
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m_deferred.Resolve(default(T));
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} catch (Exception ex) {
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Reject(ex);
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}
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} else {
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m_deferred.Cancel(reason);
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}
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}
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public void Cancel() {
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Cancel(null);
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}
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#endregion
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}
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public class EventDescriptor : IDeferred<T> {
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readonly Action m_success;
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readonly Action<Exception> m_failed;
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readonly Action<Exception> m_cancelled;
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readonly IDeferred m_deferred;
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public EventDescriptor(Action success, Action<Exception> failed, Action<Exception> cancelled, IDeferred deferred) {
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Debug.Assert(deferred != null);
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m_success = success;
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m_failed = failed;
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m_cancelled = cancelled;
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m_deferred = deferred;
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}
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#region IDeferred implementation
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public void Resolve(T value) {
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if (m_success != null) {
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try {
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m_success();
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m_deferred.Resolve();
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} catch (Exception ex) {
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Reject(ex);
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}
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}
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}
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public void Reject(Exception error) {
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if (m_failed != null) {
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try {
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m_failed(error);
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m_deferred.Resolve();
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} catch (Exception ex) {
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m_deferred.Reject(ex);
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}
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} else {
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m_deferred.Reject(error);
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}
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}
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#endregion
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#region ICancellable implementation
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public void Cancel(Exception reason) {
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if (m_cancelled != null) {
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try {
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m_cancelled(reason);
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m_deferred.Resolve();
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} catch (Exception ex) {
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Reject(ex);
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}
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} else {
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m_deferred.Cancel(reason);
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}
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}
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public void Cancel() {
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Cancel(null);
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}
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#endregion
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}
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T m_result;
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public virtual void Resolve(T value) {
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if (BeginSetResult()) {
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m_result = value;
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EndSetResult();
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}
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}
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public void Reject(Exception error) {
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SetError(error);
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}
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public Type PromiseType {
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get {
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return typeof(T);
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}
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}
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public new T Join() {
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WaitResult(-1);
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return m_result;
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}
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public new T Join(int timeout) {
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WaitResult(timeout);
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return m_result;
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}
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public IPromise<T> On(Action<T> success, Action<Exception> error, Action<Exception> cancel) {
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AddHandler(new ValueEventDescriptor(success, error, cancel, StubDeferred.instance));
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return this;
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}
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public IPromise<T> On(Action<T> success, Action<Exception> error) {
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AddHandler(new ValueEventDescriptor(success, error, null, StubDeferred.instance));
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return this;
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}
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public IPromise<T> On(Action<T> success) {
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AddHandler(new ValueEventDescriptor(success, null, null, StubDeferred.instance));
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return this;
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}
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public IPromise<T> On(Action handler, PromiseEventType events) {
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Listen(events, handler);
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return this;
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}
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public IPromise<T2> Then<T2>(Func<T, T2> mapper, Func<Exception, T2> error, Func<Exception, T2> cancel) {
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var promise = new Promise<T2>();
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if (mapper != null)
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promise.On((Action)null, null, Cancel);
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AddHandler(new RemapDescriptor<T2>(mapper, error, cancel, promise));
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return promise;
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}
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public IPromise<T2> Then<T2>(Func<T, T2> mapper, Func<Exception, T2> error) {
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var promise = new Promise<T2>();
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if (mapper != null)
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promise.On((Action)null, null, Cancel);
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AddHandler(new RemapDescriptor<T2>(mapper, error, null, promise));
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return promise;
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}
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public IPromise<T2> Then<T2>(Func<T, T2> mapper) {
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var promise = new Promise<T2>();
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if (mapper != null)
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promise.On((Action)null, null, Cancel);
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AddHandler(new RemapDescriptor<T2>(mapper, null, null, promise));
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return promise;
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}
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public IPromise<T2> Chain<T2>(Func<T, IPromise<T2>> chained, Func<Exception, IPromise<T2>> error, Func<Exception, IPromise<T2>> cancel) {
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// this promise will be resolved when an asyc operation is started
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var promise = new Promise<IPromise<T2>>();
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AddHandler(new RemapDescriptor<IPromise<T2>>(
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chained,
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error,
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cancel,
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promise
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));
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var medium = new Promise<T2>();
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if (chained != null)
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medium.On(Cancel, PromiseEventType.Cancelled);
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// we need to connect started async operation with the medium
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// if the async operation hasn't been started by the some reason
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// report is to the medium
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promise.On(
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result => ConnectPromise<T2>(result, medium),
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medium.Reject,
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medium.Cancel
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);
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return medium;
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}
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static void ConnectPromise<T2>(IPromise<T2> result, Promise<T2> medium) {
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if (result != null) {
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result.On(
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medium.Resolve,
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medium.Reject,
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medium.Cancel
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);
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medium.On(result.Cancel, PromiseEventType.Cancelled);
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} else {
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medium.Reject(
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new NullReferenceException(
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"The chained asynchronous operation returned" +
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" 'null' where the promise instance is expected"
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)
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);
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}
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}
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public IPromise<T2> Chain<T2>(Func<T, IPromise<T2>> chained, Func<Exception, IPromise<T2>> error) {
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return Chain(chained, error, null);
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}
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public IPromise<T2> Chain<T2>(Func<T, IPromise<T2>> chained) {
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return Chain(chained, null, null);
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}
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public IPromise Then(Action success, Action<Exception> error, Action<Exception> cancel) {
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var promise = new Promise();
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if (success != null)
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promise.On(null, null, Cancel);
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AddHandler(new EventDescriptor(success, error, cancel, promise));
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return promise;
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}
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public IPromise Then(Action success, Action<Exception> error) {
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return Then(success, error, null);
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}
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public IPromise Then(Action success) {
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return Then(success, null, null);
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}
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public IPromise Chain(Func<IPromise> chained, Func<Exception, IPromise> error, Func<Exception, IPromise> cancel) {
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var promise = new Promise<IPromise>();
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AddHandler(
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new RemapDescriptor<IPromise>(
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x => chained(),
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error,
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cancel,
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promise
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)
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);
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var medium = new Promise();
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if (chained != null)
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medium.On(null, null, Cancel);
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promise.On(
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result => ConnectPromise(result, medium),
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medium.Reject,
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|
medium.Cancel
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);
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return medium;
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}
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static void ConnectPromise(IPromise result, Promise medium) {
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|
if (result != null) {
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result.On(
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medium.Resolve,
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medium.Reject,
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|
medium.Cancel
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);
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medium.On(null, null, result.Cancel);
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} else {
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|
medium.Reject(
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|
new NullReferenceException(
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|
"The chained asynchronous operation returned" +
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|
" 'null' where the promise instance is expected"
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|
)
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|
);
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}
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}
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public IPromise Chain(Func<IPromise> chained, Func<Exception, IPromise> error) {
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|
return Chain(chained, error, null);
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|
}
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public IPromise Chain(Func<IPromise> chained) {
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|
return Chain(chained, null, null);
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|
}
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public IPromise On(Action success, Action<Exception> error, Action<Exception> cancel) {
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|
AddHandler(new EventDescriptor(success,error,cancel, StubDeferred.instance));
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|
return this;
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|
}
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|
public IPromise On(Action success, Action<Exception> error) {
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|
|
AddHandler(new EventDescriptor(success, error, null, StubDeferred.instance));
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|
return this;
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|
}
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public IPromise On(Action success) {
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|
Listen(PromiseEventType.Success, success);
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|
return this;
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|
}
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|
IPromise IPromise.On(Action handler, PromiseEventType events) {
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|
|
Listen(events,handler);
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|
|
return this;
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|
}
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|
public IPromise<T2> Cast<T2>() {
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|
|
return (IPromise<T2>)this;
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|
|
}
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|
|
#region implemented abstract members of AbstractPromise
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|
|
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|
protected override void SignalSuccess(IDeferred<T> handler) {
|
|
|
handler.Resolve(m_result);
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|
|
}
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|
|
|
|
protected override void SignalError(IDeferred<T> handler, Exception error) {
|
|
|
handler.Reject(error);
|
|
|
}
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|
|
|
|
protected override void SignalCancelled(IDeferred<T> handler, Exception reason) {
|
|
|
handler.Cancel(reason);
|
|
|
}
|
|
|
|
|
|
protected override void Listen(PromiseEventType events, Action handler) {
|
|
|
if (handler != null)
|
|
|
AddHandler(new ListenerDescriptor(handler, events));
|
|
|
}
|
|
|
|
|
|
#endregion
|
|
|
|
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|
public static IPromise<T> ResultToPromise(T value) {
|
|
|
var p = new Promise<T>();
|
|
|
p.Resolve(value);
|
|
|
return p;
|
|
|
}
|
|
|
|
|
|
public static IPromise<T> ExceptionToPromise(Exception error) {
|
|
|
var p = new Promise<T>();
|
|
|
p.Reject(error);
|
|
|
return p;
|
|
|
}
|
|
|
|
|
|
}
|
|
|
}
|
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|
