Universal Type Extender

// file     : ExtensionRepository.RepositoryItemTargetKey.cs
// project  : UniversalTypeExtender
// author   : Thorsten Bruning
// date     : 18.10.2011

using System;

namespace TB.ComponentModel.Infrastructure {
    partial class ExtensionRepository {

        /// <summary>
        /// Represents the key of an ExtensionRepositoryItem.
        /// Only for infrastructure.
        /// </summary>
        public class RepositoryItemTargetKey {

            private readonly WeakReference mTarget;
            private readonly int mHashCode;

            /// <summary>
            /// Gets the target.
            /// </summary>
            public object Target {
                get { return mTarget.Target; }
            }

            /// <summary>
            /// Initializes a new instance of the RepositoryItemTargetKey class.
            /// </summary>
            /// <param name="target">RepositoryItem.</param>
            public RepositoryItemTargetKey(object target) {
                mTarget = new WeakReference(target);
                if(target != null) {
                    mHashCode = target.GetHashCode();
                }
            }

            /// <summary>
            /// Serves as a hash function for this type.
            /// </summary>
            /// <returns>A hash code for this instance.</returns>
            public override int GetHashCode() {
                return mHashCode;
            }

            /// <summary>
            /// Determines whether the specified object is equal to this instance.
            /// </summary>
            /// <param name="obj">The object to compare with this instance.</param>
            /// <returns>true if the specified object is equal to this instance otherwise, false.</returns>
            public override bool Equals(object obj) {
                if (obj == null) {
                    return false;
                }
                if (obj.GetType() != GetType()) {
                    return false;
                }
                object target = Target;
                object objectsTarget = ((RepositoryItemTargetKey)obj).Target;
                if (target == null && objectsTarget == null) {
                    return true;
                }
                if (target == null) {
                    return false;
                }
                if(objectsTarget == null) {
                    return false;
                }
                return target.Equals(objectsTarget);
            }

        }
    }
}