SwitchExtensions.cs

using System;

namespace UniRx {

    public static class SwitchExtensions {

        public static IObservable<OUT> SwitchSelectWhenTrue<OUT>( this IObservable<bool> observable, Func<IObservable<OUT>> resultIfTrue ) {
            return observable.Select(value => value == true ? resultIfTrue() : Observable.Empty<OUT>()).Switch();
        }

        public static IObservable<OUT> SwitchSelectWhenFalse<OUT>( this IObservable<bool> observable, Func<IObservable<OUT>> resultIfFalse ) {
            return observable.Select(value => value == false ? resultIfFalse() : Observable.Empty<OUT>()).Switch();
        }

        public static IObservable<OUT> SwitchSelectWhenNull<OUT, IN>( this IObservable<IN> observable, Func<IObservable<OUT>> resultWhenNull ) where IN : class {
            return observable.Select(value => value == null ? resultWhenNull() : Observable.Empty<OUT>()).Switch();
        }

        public static IObservable<OUT> SwitchSelectWhenNotNull<OUT, IN>( this IObservable<IN> observable, Func<IN, IObservable<OUT>> resultWhenNotNull ) where IN : class {
            return observable.Select(value => value != null ? resultWhenNotNull(value) : Observable.Empty<OUT>()).Switch();
        }

        public static IObservable<OUT> SwitchSelect<OUT, IN>( this IObservable<IN> observable, Func<IN, IObservable<OUT>> result ) {
            return observable.Select(result).Switch();
        }
    }

}