ntpa/Ntp.Analyzer.Objects/PersistentObject.cs

//
// PersistentObject.cs
//
// Author:
//       Carsten Sonne Larsen <cs@innolan.dk>
//
// Copyright (c) 2013-2016 Carsten Sonne Larsen
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in
// all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
// THE SOFTWARE.
using System;

namespace Ntp.Analyzer.Objects
{
    public abstract class PersistentObject
    {
        private int id;
        private bool newObject;

        /// <summary>
        /// Initializes a new instance of the <see cref="Ntp.Analyzer.Objects.PersistentObject" /> class.
        /// </summary>
        /// <param name="id">Identifier.</param>
        /// <remarks>
        /// Constructor used when creating instances from data storage.
        /// </remarks>
        protected PersistentObject(int id)
        {
            this.id = id;
            newObject = false;
        }

        /// <summary>
        /// Initializes a new instance of the <see cref="Ntp.Analyzer.Objects.PersistentObject" /> class.
        /// </summary>
        protected PersistentObject()
        {
            id = -1;
            newObject = true;
        }

        /// <summary>
        /// Gets the identifier.
        /// </summary>
        /// <remarks>
        /// The identifier is equal to the primary key in database terminology.
        /// </remarks>
        /// <value>The identifier.</value>
        public int Id
        {
            get { return id; }
        }

        /// <summary>
        /// Gets a value indicating whether this <see cref="Ntp.Analyzer.Objects.PersistentObject" /> is a new object
        /// which does not yet exists in the peristing storage (database etc).
        /// </summary>
        /// <value>
        ///     <c>true</c> if new object; otherwise, <c>false</c>.
        /// </value>
        public bool NewObject
        {
            get { return newObject; }
            protected set { newObject = value; }
        }

        /// <summary>
        /// Sets the identifier after the object have been stored in persistent storage.
        /// </summary>
        /// <param name="id">Identifier.</param>
        public void SetId(int id)
        {
            this.id = id;
            newObject = false;
        }

        public override bool Equals(Object obj)
        {
            if (obj == null)
                return false;

            if (obj.GetType () != GetType ())
                return false;

            return 
                newObject ? 
                base.Equals(obj) :
                id == ((PersistentObject)obj).Id;
        }

        public override int GetHashCode()
        {
            return 
                newObject ?
                base.GetHashCode() :
                (int)(id * 2654435761 % 2 ^ 32);
        }

        /// <summary>
        /// Returns a <see cref="System.String" /> that represents the current <see cref="Ntp.Analyzer.Objects.PersistentObject" />.
        /// </summary>
        /// <returns>
        /// A <see cref="System.String" /> that represents the current <see cref="Ntp.Analyzer.Objects.PersistentObject" />.
        /// </returns>
        public override string ToString()
        {
            return string.Format("[PersistentObject: Id={0}, NewObject={1}]", Id, NewObject);
        }
    }
}