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/***************************************************************************\
*
* File: Maps.cs
*
* Description:
* Contains specialized data structures for mapping a key to data.
*
* Copyright (C) 2002 by Microsoft Corporation. All rights reserved.
*
\***************************************************************************/
using System;
using System.Collections;
using System.Windows;
namespace MS.Utility
{
/***************************************************************************\
*****************************************************************************
*
* DTypeMap (DType --> Object)
*
* Maps the first N used DependencyObject-derived types via an array
* (low constant time lookup) for mapping. After which falls back on a
* hash table.
*
* - Fastest gets and sets (normally single array access).
* - Large memory footprint.
*
* Starting mapping is all map to null
*
*****************************************************************************
\***************************************************************************/
using MS.Internal.PresentationCore;
[FriendAccessAllowed] // Built into Core, also used by Framework.
internal class DTypeMap
{
public DTypeMap(int entryCount)
{
// Constant Time Lookup entries (array size)
_entryCount = entryCount;
_entries = new object[_entryCount];
_activeDTypes = new ItemStructList<DependencyObjectType>(128);
}
public object this[DependencyObjectType dType]
{
get
{
if (dType.Id < _entryCount)
{
return _entries[dType.Id];
}
else
{
if (_overFlow != null)
{
return _overFlow[dType];
}
return null;
}
}
set
{
if (dType.Id < _entryCount)
{
_entries[dType.Id] = value;
}
else
{
if (_overFlow == null)
{
_overFlow = new Hashtable();
}
_overFlow[dType] = value;
}
_activeDTypes.Add(dType);
}
}
// Return list of non-null DType mappings
public ItemStructList<DependencyObjectType> ActiveDTypes
{
get { return _activeDTypes; }
}
// Clear the data-structures to be able to start over
public void Clear()
{
for (int i=0; i<_entryCount; i++)
{
_entries[i] = null;
}
for (int i=0; i<_activeDTypes.Count; i++)
{
_activeDTypes.List[i] = null;
}
if (_overFlow != null)
{
_overFlow.Clear();
}
}
private int _entryCount;
private object[] _entries;
private Hashtable _overFlow;
private ItemStructList<DependencyObjectType> _activeDTypes;
}
}
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