TrackingCollection.cs

#region License
// Copyright (c) Jeremy Skinner (http://www.jeremyskinner.co.uk)
// 
// Licensed under the Apache License, Version 2.0 (the "License"); 
// you may not use this file except in compliance with the License. 
// You may obtain a copy of the License at 
// 
// http://www.apache.org/licenses/LICENSE-2.0 
// 
// Unless required by applicable law or agreed to in writing, software 
// distributed under the License is distributed on an "AS IS" BASIS, 
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 
// See the License for the specific language governing permissions and 
// limitations under the License.
// 
// The latest version of this file can be found at http://fluentvalidation.codeplex.com
#endregion

namespace ServiceStack.FluentValidation.Internal
{
    using System;
    using System.Collections;
    using System.Collections.Generic;

    public class TrackingCollection<T> : IEnumerable<T>
    {
        readonly List<T> innerCollection = new List<T>();
        public event Action<T> ItemAdded;

        public void Add(T item) {
            innerCollection.Add(item);

            if (ItemAdded != null) {
                ItemAdded(item);
            }
        }

        public IDisposable OnItemAdded(Action<T> onItemAdded) {
            ItemAdded += onItemAdded;
            return new EventDisposable(this, onItemAdded);
        }

        public IEnumerator<T> GetEnumerator() {
            return innerCollection.GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator() {
            return GetEnumerator();
        }

        class EventDisposable : IDisposable {
            readonly TrackingCollection<T> parent;
            readonly Action<T> handler;

            public EventDisposable(TrackingCollection<T> parent, Action<T> handler) {
                this.parent = parent;
                this.handler = handler;
            }

            public void Dispose() {
                parent.ItemAdded -= handler;
            }
        }
    }
}