ImmutableUndoRedo

A lightweight, flexible and easy to use do/undo/redo implementation based on immutable objects for .NET.

Getting started

To install ImmutableUndoRedo run the following command from the Package Manager Console:

PM> install-package ImmutableUndoRedo

Sample

Activity implementation

internal class Activity : IActivity<Activity>
{
    private readonly int id;

    private readonly int doCalls;

    private readonly int undoCalls;

    public Activity(int id)
    {
        this.id = id;
    }

    private Activity(int id, int doCalls, int undoCalls)
        : this(id)
    {
        this.doCalls = doCalls;
        this.undoCalls = undoCalls;
    }

    public Activity Do()
    {
        Console.WriteLine("Do activity #{0}", this.id);

        return new Activity(this.id, this.doCalls + 1, this.undoCalls);
    }

    public Activity Undo()
    {
        Console.WriteLine("Undo activity #{0}", this.id);

        return new Activity(this.id, this.doCalls, this.undoCalls + 1);
    }

    public override string ToString()
    {
        return $"Activity {{Id = {this.id}, #Do calls = {this.doCalls}, #Undo calls = {this.undoCalls}}}";
    }
}

Use of the History class

class Program
{
    static void Main(string[] args)
    {
        var history = History<Activity>.Create()
                                       .Do(new Activity(1))
                                       .Do(new Activity(2))
                                       .Do(new Activity(3))
                                       .Do(new Activity(4))
                                       .Do(new Activity(5))
                                       .Undo()
                                       .Undo()
                                       .Undo()
                                       .Redo();

        Console.WriteLine("\n\nDone activities:");
        var done = new List<Activity>();
        history.CopyDoneTo(done);
        done.ForEach(Console.WriteLine);

        Console.WriteLine("\n\nUndone activities:");
        var undone = new List<Activity>();
        history.CopyUndoneTo(undone);
        undone.ForEach(Console.WriteLine);

        Console.ReadLine();
    }
}

// Console output:
Do activity #1
Do activity #2
Do activity #3
Do activity #4
Do activity #5
Undo activity #5
Undo activity #4
Undo activity #3
Do activity #3


Done activities:
Activity {Id = 1, #Do calls = 1, #Undo calls = 0}
Activity {Id = 2, #Do calls = 1, #Undo calls = 0}
Activity {Id = 3, #Do calls = 2, #Undo calls = 1}


Undone activities:
Activity {Id = 5, #Do calls = 1, #Undo calls = 1}
Activity {Id = 4, #Do calls = 1, #Undo calls = 1}