XmlDataCollection.cs source code in C# .NET

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                         / 4.0 / 4.0 / untmp / DEVDIV_TFS / Dev10 / Releases / RTMRel / wpf / src / Framework / MS / Internal / Data / XmlDataCollection.cs / 1305600 / XmlDataCollection.cs
                        
                        
                            //---------------------------------------------------------------------------- 
//
// 
//    Copyright (C) 2003 by Microsoft Corporation.  All rights reserved.
//  
//
// 
// 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
{
    /// 
    /// Implementation of a data collection based on ArrayList, 
    /// implementing INotifyCollectionChanged to notify listeners
    /// when items get added, removed or the whole list is refreshed. 
    ///  
    internal class XmlDataCollection : ReadOnlyObservableCollection
    { 
        //-----------------------------------------------------
        //
        //  Constructors
        // 
        //-----------------------------------------------------
 
        ///  
        /// Initializes a new instance of XmlDataCollection that is empty and has the specified initial capacity.
        ///  
        /// Parent Xml Data Source
        internal XmlDataCollection(XmlDataProvider xmlDataProvider) : base(new ObservableCollection())
        {
            _xds = xmlDataProvider; 
        }
 
        //------------------------------------------------------ 
        //
        //  Internal Properties 
        //
        //-----------------------------------------------------

        ///  
        /// XmlNamespaceManager property, XmlNamespaceManager used for executing XPath queries.
        ///  
        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; 
    } 
}
 



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

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