C# IObservable.Cast方法代码示例

        public FileTailer(FileInfo file,
                IObservable<FileSearchResult> filter,
                IObservable<ScrollRequest> scrollRequest,
                ILogger logger,
                IScheduler scheduler = null)
        {
            if (file == null) throw new ArgumentNullException(nameof(file));
            if (filter == null) throw new ArgumentNullException(nameof(filter));
            if (logger == null) throw new ArgumentNullException(nameof(logger));

            logger.Info($"Constructing file tailer for {file.FullName}");

            var lines = new SourceList<Line>();
            Lines = lines.AsObservableList();

            var isBusy = new Subject<bool>();
            IsSearching = isBusy.AsObservable();

            var locker = new object();
            scrollRequest = scrollRequest.Synchronize(locker);

            var fileWatcher = file.WatchFile(scheduler: scheduler)
                            .DistinctUntilChanged()
                            .TakeWhile(notification => notification.Exists).Repeat()
                            .Replay(1).RefCount();

            var indexer = fileWatcher.Index().Replay(1).RefCount();

            //compare latest lines and latest filter and only take the filtered results it is not empty
            var latestLines = indexer.Cast<ILineProvider>().Synchronize(locker);
            var latestFilter = filter.Cast<ILineProvider>().Synchronize(locker);
            var latest = latestLines.CombineLatest(latestFilter, (l, f) => f.IsEmpty ? l : f);

            MatchedLines = latest.Select(provider => provider.Count);
            TotalLines = latestLines.Select(x => x.Count);
            FileSize = fileWatcher.Select(notification => notification.Size);
            IsLoading = indexer.Take(1).Select(_ => false).StartWith(true);

            var aggregator = latest.CombineLatest(scrollRequest, (currentLines, scroll) =>
            {
                return currentLines.ReadLines(scroll).ToArray();
            })
            .Subscribe(currentPage =>
            {
                var previous = lines.Items.ToArray();
                var added = currentPage.Except(previous).ToArray();
                var removed = previous.Except(currentPage).ToArray();

                lines.Edit(innerList =>
                {
                    if (removed.Any()) innerList.RemoveMany(removed);
                    if (added.Any()) innerList.AddRange(added);
                });

            });

            //var aggregator = latest.CombineLatest(scrollRequest, (currentLines, scroll) =>
            //{
            //    //TODO: Read entire page, the check which lines should be added and which shold be removed
            //    //as part of that work, get the maximum inded [this is the head!]

            //    //   Debug.WriteLine($"{scroll.Mode}, {scroll.FirstIndex}, {scroll.PageSize}");

            //    var currentPage = currentLines.GetIndicies(scroll).ToArray();

            //    var previous = lines.Items.Select(l => l.LineInfo).ToArray();
            //    var removed = previous.Except(currentPage, LineInfo.LineIndexComparer).ToArray();
            //    var added = currentPage.Except(previous, LineInfo.LineIndexComparer).ToArray();
            //    //calculated added and removed lines
            //    var removedLines = lines.Items.Where(l => removed.Contains(l.LineInfo)).ToArray();

            //    Func<long, DateTime?> isTail = l =>
            //    {
            //        //account for time with tail (i.e. add time to ILineProvider.TailStartsAt )
            //        var tail = currentLines.TailStartsAt;
            //        var onTail = tail != -1 && l >= tail;
            //        return onTail ? DateTime.Now : (DateTime?)null;
            //    };

            //    //Console.WriteLine();
            //    //finally we can load the line from the file todo: Add encdoing back in
            //    var newLines = file.ReadLine(added, (lineIndex, text, position) => new Line(lineIndex, text, isTail(position)), Encoding.UTF8).ToArray();

            //    return new { NewLines = newLines, OldLines = removedLines };
            //})
            //.Where(fn => fn.NewLines.Length + fn.OldLines.Length > 0)
            //.Subscribe(changes =>
            //{
            //    //update observable list
            //    lines.Edit(innerList =>
            //{
            //    if (changes.OldLines.Any()) innerList.RemoveMany(changes.OldLines);
            //    if (changes.NewLines.Any()) innerList.AddRange(changes.NewLines);
            //});
            //});

            _cleanUp = new CompositeDisposable(Lines, lines, aggregator, Disposable.Create(() => isBusy.OnCompleted()));
        }

 public static ICurrencyPair ToCurrencyPair(this NSString nsString, IObservable<PriceDto> priceStream)
 {
     var pair = JsonConvert.DeserializeObject<CurrencyPair>(nsString);
     pair.PriceStream = priceStream.Cast<IPrice>();
     return pair;
 }