ContainerTracking.cs source code in C# .NET

                        Code:
                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / System / Windows / Controls / ContainerTracking.cs / 1305600 / ContainerTracking.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// Copyright (C) Microsoft Corporation.  All rights reserved.
//
//--------------------------------------------------------------------------- 

using System; 
using System.Collections; 
using System.Collections.Generic;
using System.Collections.ObjectModel; 
using System.Collections.Specialized;
using System.ComponentModel;
using System.Diagnostics;
using System.Windows; 
using System.Windows.Controls.Primitives;
using System.Windows.Input; 
 
namespace System.Windows.Controls
{ 
    /// 
    ///     Represents a node in a linked list used to track active containers.
    ///     Containers should instantiate and references these.
    ///     Parents hold onto the linked list. 
    ///
    ///     The list is iterated in order to call a variety of methods on containers 
    ///     in response to changes on the parent. 
    /// 
    internal class ContainerTracking 
    {
        internal ContainerTracking(T container)
        {
            _container = container; 
        }
 
        ///  
        ///     The row container that this object represents.
        ///  
        internal T Container
        {
            get { return _container; }
        } 

        ///  
        ///     The next node in the list. 
        /// 
        internal ContainerTracking Next 
        {
            get { return _next; }
        }
 
        /// 
        ///     The previous node in the list. 
        ///  
        internal ContainerTracking Previous
        { 
            get { return _previous; }
        }

        ///  
        ///     Adds this tracker to the list of active containers.
        ///  
        /// The root of the list. 
        internal void StartTracking(ref ContainerTracking root)
        { 
            // Add the node to the root
            if (root != null)
            {
                root._previous = this; 
            }
 
            _next = root; 
            root = this;
        } 

        /// 
        ///     Removes this tracker from the list of active containers.
        ///  
        /// The root of the list.
        internal void StopTracking(ref ContainerTracking root) 
        { 
            // Unhook the node from the list
            if (_previous != null) 
            {
                _previous._next = _next;
            }
 
            if (_next != null)
            { 
                _next._previous = _previous; 
            }
 
            // Update the root reference
            if (root == this)
            {
                root = _next; 
            }
 
            // Clear the node's references 
            _previous = null;
            _next = null; 
        }

        #region Debugging Helpers
 
        /// 
        ///     Asserts that the container represented by this tracker is in the list represented by the given root. 
        ///  
        [Conditional("DEBUG")]
        internal void Debug_AssertIsInList(ContainerTracking root) 
        {
#if DEBUG
            Debug.Assert(IsInList(root), "This container should be in the tracking list.");
#endif 
        }
 
        ///  
        ///     Asserts that the container represented by this tracker is not in the list represented by the given root.
        ///  
        [Conditional("DEBUG")]
        internal void Debug_AssertNotInList(ContainerTracking root)
        {
#if DEBUG 
            Debug.Assert(!IsInList(root), "This container shouldn't be in our tracking list");
#endif 
        } 

#if DEBUG 
        /// 
        ///     Checks that this tracker is present in the list starting with root.  It's a linear walk through the list, so should be used
        ///     mostly for debugging
        ///  
        private bool IsInList(ContainerTracking root)
        { 
            ContainerTracking node = root; 

            while (node != null) 
            {
                if (node == this)
                {
                    return true; 
                }
 
                node = node._next; 
            }
 
            return false;
        }
#endif
 
        #endregion
 
        private T _container; 
        private ContainerTracking _next;
        private ContainerTracking _previous; 
    }
}

// File provided for Reference Use Only by Microsoft Corporation (c) 2007.
// Copyright (c) Microsoft Corporation. All rights reserved.
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ContainerTracking.cs source code in C# .NET

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