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//------------------------------------------------------------------------------
// <copyright file="Select.cs" company="Microsoft">
// Copyright (c) Microsoft Corporation. All rights reserved.
// </copyright>
// <owner current="true" primary="true">[....]</owner>
// <owner current="true" primary="false">[....]</owner>
//------------------------------------------------------------------------------
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;
/// <summary><see cref="DataView.ObjectID"/></summary>
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);
}
}
/// <summary>
/// Maintain the DataView before <see cref="DataView.ListChanged"/> is raised.
/// </summary>
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<DataViewListener> 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<DataViewListener> 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);
}
}
}
}
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