/BlogEngine/DotNetSlave.BusinessLogic/StateCollection.cs

namespace BlogEngine.Core

{

    using System;

    using System.Collections.Generic;

    using System.Linq;



    /// <summary>

    /// A generic collection with the ability to 

    ///     check if it has been changed.

    /// </summary>

    /// <typeparam name="T">

    /// The type of the list elements.

    /// </typeparam>

    [Serializable]

    public class StateList<T> : List<T>

    {

        ///// <summary>

        ///// Inserts an element into the collection at the specified index and marks it changed.

        ///// </summary>

        // protected override void InsertItem(int index, T item)

        // {

        // base.InsertItem(index, item);

        // _IsChanged = true;

        // }



        ///// <summary>

        ///// Removes all the items in the collection and marks it changed.

        ///// </summary>

        // protected override void ClearItems()

        // {

        // base.ClearItems();

        // _IsChanged = true;

        // }



        ///// <summary>

        ///// Removes the element at the specified index and marks the collection changed.

        ///// </summary>

        // protected override void RemoveItem(int index)

        // {

        // base.RemoveItem(index);

        // _IsChanged = true;

        // }



        ///// <summary>

        ///// Replaces the element at the specified index and marks the collection changed.

        ///// </summary>

        // protected override void SetItem(int index, T item)

        // {

        // base.SetItem(index, item);

        // _IsChanged = true;

        // }

        #region Constants and Fields



        /// <summary>

        /// Has code int.

        /// </summary>

        private int hasCode;



        #endregion



        #region Properties



        /// <summary>

        ///     Gets a value indicating whether this object's data has been changed.

        /// </summary>

        /// <returns>A value indicating if this object's data has been changed.</returns>

        public virtual bool IsChanged

        {

            get

            {

                return this.GetHashCode() != this.hasCode;

            }

        }



        #endregion



        #region Public Methods



        /// <summary>

        /// Determines whether the specified <see cref="T:System.Object"></see> is equal to the current <see cref="T:System.Object"></see>.

        /// </summary>

        /// <param name="obj">

        /// The <see cref="T:System.Object"></see> to compare with the current <see cref="T:System.Object"></see>.

        /// </param>

        /// <returns>

        /// true if the specified <see cref="T:System.Object"></see> is equal to the current <see cref="T:System.Object"></see>; otherwise, false.

        /// </returns>

        public override bool Equals(object obj)

        {

            if (obj == null)

            {

                return false;

            }



            if (obj.GetType() == this.GetType())

            {

                return obj.GetHashCode() == this.GetHashCode();

            }



            return false;

        }



        /// <summary>

        /// Serves as a hash function for a particular type. <see cref="M:System.Object.GetHashCode"></see> is suitable for use in hashing algorithms and data structures like a hash table.

        /// </summary>

        /// <returns>

        /// A hash code for the current <see cref="T:System.Object"></see>.

        /// </returns>

        public override int GetHashCode()

        {

            var hash = this.Aggregate(string.Empty, (current, item) => current + item.GetHashCode().ToString());



            return hash.GetHashCode();

        }



        /// <summary>

        /// Marks the object as being clean, 

        ///     which means not changed.

        /// </summary>

        public virtual void MarkOld()

        {

            this.hasCode = this.GetHashCode();

            this.TrimExcess();

        }



        #endregion

    }

}