WeakReferenceKey.cs source code in C# .NET

Source code for the .NET framework in C#

                        
Code:

                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Base / MS / Internal / WeakReferenceKey.cs / 1305600 / WeakReferenceKey.cs
                        

                        
                            //---------------------------------------------------------------------------------------- 
//
// 
//    Copyright (C) Microsoft Corporation.  All rights reserved.
//  
//
// Description: 
//  This file defines a class that holds a weak reference to an object.  It preserves the hashcode 
//  of the object and is intended to be used as a key in hashtables or dictionaries.
// 
//-------------------------------------------------------------------------------------


using System; 
using MS.Internal;
 
namespace MS.Internal.Utility 
{
 	///  
    /// Helper class that allows using a weak reference to an item as a key in a hash table.
    /// 
    internal class WeakReferenceKey
    { 
        public WeakReferenceKey(T item)
        { 
            Invariant.Assert(item != null); 

            _item = new WeakReference(item); 
            _hashCode = item.GetHashCode();
        }

        public T Item 
        {
            get { return (T)_item.Target; } 
        } 

        public override bool Equals(object o) 
        {
            if (o == this)
                return true;
 
            WeakReferenceKey key = o as WeakReferenceKey;
            if (key != null) 
            { 
                T item = this.Item;
 
                if (item == null)
                    return false;   // a stale key matches nothing (except itself)

                return this._hashCode == key._hashCode && 
                        Object.Equals(item, key.Item);
            } 
 
            return false;
        } 

        public override int GetHashCode()
        {
            return _hashCode; 
        }
 
        private WeakReference _item; 
        private int _hashCode;
    } 
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.

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