DataViewListener.cs source code in C# .NET

                        Code:
                         / DotNET / DotNET / 8.0 / untmp / whidbey / REDBITS / ndp / fx / src / Data / System / Data / DataViewListener.cs / 2 / DataViewListener.cs
                        
                        
                            //------------------------------------------------------------------------------ 
// 
//     Copyright (c) Microsoft Corporation.  All rights reserved.
// 
// [....] 
// [....]
//----------------------------------------------------------------------------- 
 
namespace System.Data {
 
    using System;
    using System.ComponentModel;
    using System.Collections.Generic;
    using System.Diagnostics; 

    internal sealed class DataViewListener { 
 
        private readonly WeakReference _dvWeak;
        private DataTable _table; 
        private Index _index;

        /// 
        internal readonly int ObjectID; 

        internal DataViewListener(DataView dv) { 
            this.ObjectID = dv.ObjectID; 
            _dvWeak = new WeakReference(dv);
        } 

        private void ChildRelationCollectionChanged(object sender, CollectionChangeEventArgs e) {
            DataView dv = (DataView)_dvWeak.Target;
            if (dv != null) { 
                dv.ChildRelationCollectionChanged(sender, e);
            } 
            else { 
                CleanUp(true);
            } 
        }

        private void ParentRelationCollectionChanged(object sender, CollectionChangeEventArgs e) {
            DataView dv = (DataView)_dvWeak.Target; 
            if (dv != null) {
                dv.ParentRelationCollectionChanged(sender, e); 
            } 
            else {
                CleanUp(true); 
            }
        }

        private void ColumnCollectionChanged(object sender, CollectionChangeEventArgs e) { 
            DataView dv = (DataView)_dvWeak.Target;
            if (dv != null) { 
                dv.ColumnCollectionChangedInternal(sender, e); 
            }
            else { 
                CleanUp(true);
            }
        }
 
        /// 
        /// Maintain the DataView before  is raised. 
        ///  
        internal void MaintainDataView(ListChangedType changedType, DataRow row, bool trackAddRemove) {
            DataView dv = (DataView)_dvWeak.Target; 
            if (dv != null) {
                dv.MaintainDataView(changedType, row, trackAddRemove);
            }
            else { 
                CleanUp(true);
            } 
        } 

        internal void IndexListChanged(ListChangedEventArgs e) { 
            DataView dv = (DataView)_dvWeak.Target;
            if (dv != null) {
                dv.IndexListChangedInternal(e);
            } 
            else {
                CleanUp(true); 
            } 
        }
 
        internal void RegisterMetaDataEvents(DataTable table) {
            Debug.Assert(null == _table, "DataViewListener already registered table");
            _table = table;
            if (table != null) { 
                // actively remove listeners without a target
                RegisterListener(table); 
 
                // start listening to events
                CollectionChangeEventHandler handlerCollection = new CollectionChangeEventHandler(ColumnCollectionChanged); 
                table.Columns.ColumnPropertyChanged += handlerCollection;
                table.Columns.CollectionChanged += handlerCollection;

                CollectionChangeEventHandler handlerChildRelation = new CollectionChangeEventHandler(ChildRelationCollectionChanged); 
                ((DataRelationCollection.DataTableRelationCollection)(table.ChildRelations)).RelationPropertyChanged += handlerChildRelation;
                table.ChildRelations.CollectionChanged += handlerChildRelation; 
 
                CollectionChangeEventHandler handlerParentRelation = new CollectionChangeEventHandler(ParentRelationCollectionChanged);
                ((DataRelationCollection.DataTableRelationCollection)(table.ParentRelations)).RelationPropertyChanged += handlerParentRelation; 
                table.ParentRelations.CollectionChanged += handlerParentRelation;
            }
        }
 
        internal void UnregisterMetaDataEvents() {
            UnregisterMetaDataEvents(true); 
        } 

        private void UnregisterMetaDataEvents(bool updateListeners) { 
            DataTable table = _table;
            _table = null;

            if (table != null) { 
                CollectionChangeEventHandler handlerCollection = new CollectionChangeEventHandler(ColumnCollectionChanged);
                table.Columns.ColumnPropertyChanged -= handlerCollection; 
                table.Columns.CollectionChanged -= handlerCollection; 

                CollectionChangeEventHandler handlerChildRelation = new CollectionChangeEventHandler(ChildRelationCollectionChanged); 
                ((DataRelationCollection.DataTableRelationCollection)(table.ChildRelations)).RelationPropertyChanged -= handlerChildRelation;
                table.ChildRelations.CollectionChanged -= handlerChildRelation;

                CollectionChangeEventHandler handlerParentRelation = new CollectionChangeEventHandler(ParentRelationCollectionChanged); 
                ((DataRelationCollection.DataTableRelationCollection)(table.ParentRelations)).RelationPropertyChanged -= handlerParentRelation;
                table.ParentRelations.CollectionChanged -= handlerParentRelation; 
 
                if (updateListeners) {
                    List listeners = table.GetListeners(); 
                    lock (listeners) {
                        listeners.Remove(this);
                    }
                } 
            }
        } 
 
        internal void RegisterListChangedEvent(Index index) {
            Debug.Assert(null == _index, "DataviewListener already registered index"); 
            _index = index;
            if (null != index) {
                lock (index) {
                    index.AddRef(); 
                    index.ListChangedAdd(this);
                } 
            } 
        }
 
        internal void UnregisterListChangedEvent() {
            Index index = _index;
            _index = null;
 
            if (index != null) {
                lock (index) { 
                    index.ListChangedRemove(this); 
                    if (index.RemoveRef() <= 1) {
                        index.RemoveRef(); 
                    }
                }
            }
        } 

        private void CleanUp(bool updateListeners) { 
            UnregisterMetaDataEvents(updateListeners); 
            UnregisterListChangedEvent();
        } 

        private void RegisterListener(DataTable table) {
            List listeners = table.GetListeners();
            lock (listeners) { 
                for (int i = listeners.Count - 1; 0 <= i; --i) {
                    DataViewListener listener = listeners[i]; 
                    if (!listener._dvWeak.IsAlive) { 
                        listeners.RemoveAt(i);
                        listener.CleanUp(false); 
                    }
                }
                listeners.Add(this);
            } 
        }
    } 
} 

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

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