mcs/class/referencesource/System.Data/System/Data/DataViewListener.cs

   1 //------------------------------------------------------------------------------
   2 // <copyright file="Select.cs" company="Microsoft">
   3 //     Copyright (c) Microsoft Corporation.  All rights reserved.
   4 // </copyright>
   5 // <owner current="true" primary="true">Microsoft</owner>
   6 // <owner current="true" primary="false">Microsoft</owner>
   7 //------------------------------------------------------------------------------
   8
   9 namespace System.Data {
  10
  11     using System;
  12     using System.ComponentModel;
  13     using System.Collections.Generic;
  14     using System.Diagnostics;
  15
  16     internal sealed class DataViewListener {
  17
  18         private readonly WeakReference _dvWeak;
  19         private DataTable _table;
  20         private Index _index;
  21
  22         /// <summary><see cref="DataView.ObjectID"/></summary>
  23         internal readonly int ObjectID;
  24
  25         internal DataViewListener(DataView dv) {
  26             this.ObjectID = dv.ObjectID;
  27             _dvWeak = new WeakReference(dv);
  28         }
  29
  30         private void ChildRelationCollectionChanged(object sender, CollectionChangeEventArgs e) {
  31             DataView dv = (DataView)_dvWeak.Target;
  32             if (dv != null) {
  33                 dv.ChildRelationCollectionChanged(sender, e);
  34             }
  35             else {
  36                 CleanUp(true);
  37             }
  38         }
  39
  40         private void ParentRelationCollectionChanged(object sender, CollectionChangeEventArgs e) {
  41             DataView dv = (DataView)_dvWeak.Target;
  42             if (dv != null) {
  43                 dv.ParentRelationCollectionChanged(sender, e);
  44             }
  45             else {
  46                 CleanUp(true);
  47             }
  48         }
  49
  50         private void ColumnCollectionChanged(object sender, CollectionChangeEventArgs e) {
  51             DataView dv = (DataView)_dvWeak.Target;
  52             if (dv != null) {
  53                 dv.ColumnCollectionChangedInternal(sender, e);
  54             }
  55             else {
  56                 CleanUp(true);
  57             }
  58         }
  59
  60         /// <summary>
  61         /// Maintain the DataView before <see cref="DataView.ListChanged"/> is raised.
  62         /// </summary>
  63         internal void MaintainDataView(ListChangedType changedType, DataRow row, bool trackAddRemove) {
  64             DataView dv = (DataView)_dvWeak.Target;
  65             if (dv != null) {
  66                 dv.MaintainDataView(changedType, row, trackAddRemove);
  67             }
  68             else {
  69                 CleanUp(true);
  70             }
  71         }
  72
  73         internal void IndexListChanged(ListChangedEventArgs e) {
  74             DataView dv = (DataView)_dvWeak.Target;
  75             if (dv != null) {
  76                 dv.IndexListChangedInternal(e);
  77             }
  78             else {
  79                 CleanUp(true);
  80             }
  81         }
  82
  83         internal void RegisterMetaDataEvents(DataTable table) {
  84             Debug.Assert(null == _table, "DataViewListener already registered table");
  85             _table = table;
  86             if (table != null) {
  87                 // actively remove listeners without a target
  88                 RegisterListener(table);
  89
  90                 // start listening to events
  91                 CollectionChangeEventHandler handlerCollection = new CollectionChangeEventHandler(ColumnCollectionChanged);
  92                 table.Columns.ColumnPropertyChanged += handlerCollection;
  93                 table.Columns.CollectionChanged += handlerCollection;
  94
  95                 CollectionChangeEventHandler handlerChildRelation = new CollectionChangeEventHandler(ChildRelationCollectionChanged);
  96                 ((DataRelationCollection.DataTableRelationCollection)(table.ChildRelations)).RelationPropertyChanged += handlerChildRelation;
  97                 table.ChildRelations.CollectionChanged += handlerChildRelation;
  98
  99                 CollectionChangeEventHandler handlerParentRelation = new CollectionChangeEventHandler(ParentRelationCollectionChanged);
 100                 ((DataRelationCollection.DataTableRelationCollection)(table.ParentRelations)).RelationPropertyChanged += handlerParentRelation;
 101                 table.ParentRelations.CollectionChanged += handlerParentRelation;
 102             }
 103         }
 104
 105         internal void UnregisterMetaDataEvents() {
 106             UnregisterMetaDataEvents(true);
 107         }
 108
 109         private void UnregisterMetaDataEvents(bool updateListeners) {
 110             DataTable table = _table;
 111             _table = null;
 112
 113             if (table != null) {
 114                 CollectionChangeEventHandler handlerCollection = new CollectionChangeEventHandler(ColumnCollectionChanged);
 115                 table.Columns.ColumnPropertyChanged -= handlerCollection;
 116                 table.Columns.CollectionChanged -= handlerCollection;
 117
 118                 CollectionChangeEventHandler handlerChildRelation = new CollectionChangeEventHandler(ChildRelationCollectionChanged);
 119                 ((DataRelationCollection.DataTableRelationCollection)(table.ChildRelations)).RelationPropertyChanged -= handlerChildRelation;
 120                 table.ChildRelations.CollectionChanged -= handlerChildRelation;
 121
 122                 CollectionChangeEventHandler handlerParentRelation = new CollectionChangeEventHandler(ParentRelationCollectionChanged);
 123                 ((DataRelationCollection.DataTableRelationCollection)(table.ParentRelations)).RelationPropertyChanged -= handlerParentRelation;
 124                 table.ParentRelations.CollectionChanged -= handlerParentRelation;
 125
 126                 if (updateListeners) {
 127                     List<DataViewListener> listeners = table.GetListeners();
 128                     lock (listeners) {
 129                         listeners.Remove(this);
 130                     }
 131                 }
 132             }
 133         }
 134
 135         internal void RegisterListChangedEvent(Index index) {
 136             Debug.Assert(null == _index, "DataviewListener already registered index");
 137             _index = index;
 138             if (null != index) {
 139                 lock (index) {
 140                     index.AddRef();
 141                     index.ListChangedAdd(this);
 142                 }
 143             }
 144         }
 145
 146         internal void UnregisterListChangedEvent() {
 147             Index index = _index;
 148             _index = null;
 149
 150             if (index != null) {
 151                 lock (index) {
 152                     index.ListChangedRemove(this);
 153                     if (index.RemoveRef() <= 1) {
 154                         index.RemoveRef();
 155                     }
 156                 }
 157             }
 158         }
 159
 160         private void CleanUp(bool updateListeners) {
 161             UnregisterMetaDataEvents(updateListeners);
 162             UnregisterListChangedEvent();
 163         }
 164
 165         private void RegisterListener(DataTable table) {
 166             List<DataViewListener> listeners = table.GetListeners();
 167             lock (listeners) {
 168                 for (int i = listeners.Count - 1; 0 <= i; --i) {
 169                     DataViewListener listener = listeners[i];
 170                     if (!listener._dvWeak.IsAlive) {
 171                         listeners.RemoveAt(i);
 172                         listener.CleanUp(false);
 173                     }
 174                 }
 175                 listeners.Add(this);
 176             }
 177         }
 178     }
 179 }