|
//---------------------------------------------------------------------------
//
// <copyright file="XmlDataCollection.cs" company="Microsoft">
// Copyright (C) 2003 by Microsoft Corporation. All rights reserved.
// </copyright>
//
//
// Description: Data collection produced by an XmlDataProvider
//
// Specs: http://avalon/connecteddata/M5%20Specs/IDataCollection.mht
//
//---------------------------------------------------------------------------
using System.Xml;
using System.Collections.ObjectModel;
using System.Collections.Specialized;
using System.Windows.Data;
using System.Windows.Markup;
namespace MS.Internal.Data
{
/// <summary>
/// Implementation of a data collection based on ArrayList,
/// implementing INotifyCollectionChanged to notify listeners
/// when items get added, removed or the whole list is refreshed.
/// </summary>
internal class XmlDataCollection : ReadOnlyObservableCollection<XmlNode>
{
//------------------------------------------------------
//
// Constructors
//
//------------------------------------------------------
/// <summary>
/// Initializes a new instance of XmlDataCollection that is empty and has the specified initial capacity.
/// </summary>
/// <param name="xmlDataProvider">Parent Xml Data Source</param>
internal XmlDataCollection(XmlDataProvider xmlDataProvider) : base(new ObservableCollection<XmlNode>())
{
_xds = xmlDataProvider;
}
//------------------------------------------------------
//
// Internal Properties
//
//------------------------------------------------------
/// <summary>
/// XmlNamespaceManager property, XmlNamespaceManager used for executing XPath queries.
/// </summary>
internal XmlNamespaceManager XmlNamespaceManager
{
get
{
if (_nsMgr == null && _xds != null)
_nsMgr = _xds.XmlNamespaceManager;
return _nsMgr;
}
set { _nsMgr = value; }
}
internal XmlDataProvider ParentXmlDataProvider
{
get { return _xds; }
}
//------------------------------------------------------
//
// Internal Methods
//
//------------------------------------------------------
// return true if the counts are different or the identity of the nodes have changed
internal bool CollectionHasChanged(XmlNodeList nodes)
{
int count = this.Count;
if (count != nodes.Count)
return true;
for (int i = 0; i < count; ++i)
{
if (this[i] != nodes[i])
return true;
}
return false;
}
// Update the collection using new query results
internal void SynchronizeCollection(XmlNodeList nodes)
{
if (nodes == null)
{
Items.Clear();
return;
}
int i = 0, j;
while (i < this.Count && i < nodes.Count)
{
if (this[i] != nodes[i])
{
// starting after current node, see if the old node is still in the new list.
for (j = i + 1; j < nodes.Count; ++j)
{
if (this[i] == nodes[j])
{
break;
}
}
if (j < nodes.Count)
{
// the node from existing collection is found at [j] in the new collection;
// this means the node(s) [i ~ j-1] in new collection should be inserted.
while (i < j)
{
Items.Insert(i, nodes[i]);
++i;
}
++i; // advance to next node
}
else
{
// the node from existing collection is no longer in
// the new collection, delete it.
Items.RemoveAt(i);
// do not advance to the next node
}
}
else
{
// nodes are the same; advance to the next node.
++i;
}
}
// Remove any extra nodes left over in the old collection
while (i < this.Count)
{
Items.RemoveAt(i);
}
// Add any extra new nodes from the new collection
while (i < nodes.Count)
{
Items.Insert(i, nodes[i]);
++i;
}
}
private XmlDataProvider _xds;
private XmlNamespaceManager _nsMgr;
}
}
|