using System;

using System.Collections.Generic;

using System.ComponentModel;

using System.Linq.Expressions;

using System.Reactive.Concurrency;

using System.Reactive.Disposables;

using System.Reactive.Linq;

using System.Runtime.CompilerServices;

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello World");

    }

}

​

​

    public partial class HostContainer

    {

    public partial class Host : INotifyPropertyChanged

    {

        private HostContainer.Host.ViewModelHost _viewModel;

        private string _value;

​

        public event PropertyChangedEventHandler PropertyChanged;

​

        private string Value

        {

            get => _value;

            set => RaiseAndSetIfChanged(ref _value, value);

        }

​

        public HostContainer.Host.ViewModelHost ViewModel

        {

            get => _viewModel;

            set => RaiseAndSetIfChanged(ref _viewModel, value);

        }

        public IDisposable GetTwoWayBindSubscription()

        {

            var instance = this;

            return this.Bind(ViewModel, x => x.Value, x => x.Value);

        }

​

        public IObservable<object> GetWhenChangedViewModelObservable()

        {

            return this.WhenChanged(x => x.ViewModel);

        }

​

        public IObservable<object> GetWhenChangedObservable()

        {

            return this.WhenChanged(x => x.Value);

        }

​

        protected void RaiseAndSetIfChanged<T>(ref T fieldValue, T value, [CallerMemberName] string propertyName = null)

        {

            if (EqualityComparer<T>.Default.Equals(fieldValue, value))

            {

                return;

            }

​

            fieldValue = value;

            OnPropertyChanged(propertyName);

        }

​

        protected virtual void OnPropertyChanged(string propertyName)

        {

            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

        }

​

    protected internal partial class ViewModelHost : INotifyPropertyChanged

    {

        private string _value;

        private ViewModelHost _child;

​

        public event PropertyChangedEventHandler PropertyChanged;

​

        internal string Value

        {

            get => _value;

            set => RaiseAndSetIfChanged(ref _value, value);

        }

​

        internal ViewModelHost Child

        {

            get => _child;

            set => RaiseAndSetIfChanged(ref _child, value);

        }

        public IObservable<object> GetWhenChangedObservable()

        {

            var instance = this;

            return this.WhenChanged(x => x.Value);

        }

​

        protected void RaiseAndSetIfChanged<T>(ref T fieldValue, T value, [CallerMemberName] string propertyName = null)

        {

            if (EqualityComparer<T>.Default.Equals(fieldValue, value))

            {

                return;

            }

​

            fieldValue = value;

            OnPropertyChanged(propertyName);

        }

​

        protected virtual void OnPropertyChanged(string propertyName)

        {

            PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

        }

​

    }

​

    }

​

    }

​

​

public partial class HostContainer

{

    public partial class Host

    {

        protected internal IObservable<HostContainer.Host.ViewModelHost> WhenChanged( Expression<Func<HostContainer.Host, HostContainer.Host.ViewModelHost>> propertyExpression, [CallerMemberName]string callerMemberName = null, [CallerFilePath]string callerFilePath = null, [CallerLineNumber]int callerLineNumber = 0) =>Observable.Create<HostContainer.Host.ViewModelHost>(observer=>

    {

        if ( this == null) return Disposable.Empty;

        observer.OnNext(this.ViewModel);

        PropertyChangedEventHandler handler = ( sender, e) =>

        {

            if ( e.PropertyName == "ViewModel") 

            {

                observer.OnNext(this.ViewModel);

            }

        };

        this.PropertyChanged+=handler;

        return Disposable.Create(( Parent: this, Handler: handler) , x=>this.PropertyChanged-=x.Handler);

    });

        public IObservable<string> WhenChanged( Expression<Func<HostContainer.Host, string>> propertyExpression, [CallerMemberName]string callerMemberName = null, [CallerFilePath]string callerFilePath = null, [CallerLineNumber]int callerLineNumber = 0) =>Observable.Create<string>(observer=>

    {

        if ( this == null) return Disposable.Empty;

        observer.OnNext(this.Value);

        PropertyChangedEventHandler handler = ( sender, e) =>

        {

            if ( e.PropertyName == "Value") 

            {

                observer.OnNext(this.Value);

            }

        };

        this.PropertyChanged+=handler;

        return Disposable.Create(( Parent: this, Handler: handler) , x=>this.PropertyChanged-=x.Handler);

    });

    }

}

​

public partial class HostContainer

{

    public partial class Host

{

    protected internal partial class ViewModelHost

    {

        protected internal IObservable<string> WhenChanged( Expression<Func<HostContainer.Host.ViewModelHost, string>> propertyExpression, [CallerMemberName]string callerMemberName = null, [CallerFilePath]string callerFilePath = null, [CallerLineNumber]int callerLineNumber = 0) =>Observable.Create<string>(observer=>

    {

        if ( this == null) return Disposable.Empty;

        observer.OnNext(this.Value);

        PropertyChangedEventHandler handler = ( sender, e) =>

        {

            if ( e.PropertyName == "Value") 

            {

                observer.OnNext(this.Value);

            }

        };

        this.PropertyChanged+=handler;

        return Disposable.Create(( Parent: this, Handler: handler) , x=>this.PropertyChanged-=x.Handler);

    });

    }

}

}

​

public partial class HostContainer

{

    public partial class Host

    {

        protected internal IDisposable Bind( HostContainer.Host.ViewModelHost targetObject, Expression<Func<HostContainer.Host, string>> fromProperty, Expression<Func<HostContainer.Host.ViewModelHost, string>> toProperty, IScheduler scheduler = null, [CallerMemberName]string callerMemberName = null, [CallerFilePath]string callerFilePath = null, [CallerLineNumber]int callerLineNumber = 0) 

    {

        IObservable<string> hostObs = this.WhenChanged(fromProperty, callerMemberName, callerFilePath, callerLineNumber);

        IObservable<string> targetObs = targetObject.WhenChanged(toProperty, callerMemberName, callerFilePath, callerLineNumber).Skip(1);

        scheduler=scheduler ?? ImmediateScheduler.Instance;

        return new CompositeDisposable(hostObs.Subscribe(x=>targetObject.Value=x), targetObs.Subscribe(x=>this.Value=x));

    }

    }

}

​

​