mcs/class/System.Web/System.Web.UI.WebControls/PagedDataSource.cs

   1 // System.Web.UI.WebControls.PagedDataSource.cs
   2 //
   3 // Author: Duncan Mak (duncan@novell.com)
   4 //         Jackson Harper  (jackson@ximian.com)
   5 //
   6 // Copyright (C) 2005 Novell, Inc (http://www.novell.com)
   7 //
   8 // Permission is hereby granted, free of charge, to any person obtaining
   9 // a copy of this software and associated documentation files (the
  10 // "Software"), to deal in the Software without restriction, including
  11 // without limitation the rights to use, copy, modify, merge, publish,
  12 // distribute, sublicense, and/or sell copies of the Software, and to
  13 // permit persons to whom the Software is furnished to do so, subject to
  14 // the following conditions:
  15 //
  16 // The above copyright notice and this permission notice shall be
  17 // included in all copies or substantial portions of the Software.
  18 //
  19 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  20 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  21 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  22 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  23 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  24 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  25 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  26 //
  27
  28 using System.Collections;
  29 using System.ComponentModel;
  30 using System.Security.Permissions;
  31
  32 namespace System.Web.UI.WebControls {
  33
  34         // CAS - no inheritance demand required because the class is sealed
  35         [AspNetHostingPermission (SecurityAction.LinkDemand, Level = AspNetHostingPermissionLevel.Minimal)]
  36         public sealed class PagedDataSource : ICollection, IEnumerable, ITypedList
  37         {
  38                 int page_size, current_page_index, virtual_count;
  39                 bool allow_paging, allow_custom_paging;
  40                 IEnumerable source;
  41
  42 #if NET_2_0
  43                 bool allow_server_paging;
  44 #endif
  45
  46                 public PagedDataSource ()
  47                 {
  48                         page_size = 10;
  49                 }
  50
  51                 public bool AllowCustomPaging {
  52                         get { return allow_custom_paging; }
  53                         set {
  54                                 allow_custom_paging = value;
  55 #if NET_2_0
  56                                 // AllowCustomPaging and AllowServerPaging are mutually exclusive
  57                                 if (allow_custom_paging)
  58                                         allow_server_paging = false;
  59 #endif
  60                         }
  61                 }
  62
  63                 public bool AllowPaging {
  64                         get { return allow_paging; }
  65                         set { allow_paging = value; }
  66                 }
  67
  68                 public int Count {
  69                         get {
  70                                 if (source == null)
  71                                         return 0;
  72
  73                                 if (IsPagingEnabled) {
  74                                         if (IsCustomPagingEnabled || !IsLastPage)
  75                                                 return page_size;
  76                                         return DataSourceCount - FirstIndexInPage;
  77                                 }
  78
  79                                 return DataSourceCount;
  80                         }
  81                 }
  82
  83                 public int CurrentPageIndex {
  84                         get { return current_page_index; }
  85                         set { current_page_index = value; }
  86                 }
  87
  88                 public IEnumerable DataSource {
  89                         get { return source; }
  90                         set { source = value; }
  91                 }
  92
  93                 public int DataSourceCount {
  94                         get {
  95                                 if (source == null)
  96                                         return 0;
  97
  98                                 if (IsCustomPagingEnabled
  99 #if NET_2_0
 100                                     || IsServerPagingEnabled
 101 #endif
 102                                 )
 103                                         return virtual_count;
 104
 105                                 if (source is ICollection)
 106                                         return ((ICollection) source).Count;
 107
 108                                 throw new HttpException ("The data source must implement ICollection");
 109                         }
 110                 }
 111
 112                 public int FirstIndexInPage {
 113                         get {
 114                                 if (!IsPagingEnabled || IsCustomPagingEnabled ||
 115 #if NET_2_0
 116                                     IsServerPagingEnabled ||
 117 #endif
 118                                     source == null)
 119                                         return 0;
 120
 121                                 return current_page_index * page_size;
 122                         }
 123                 }
 124
 125                 public bool IsCustomPagingEnabled {
 126                         get { return IsPagingEnabled && allow_custom_paging; }
 127                 }
 128
 129 #if NET_2_0
 130                 public bool IsServerPagingEnabled {
 131                         get { return IsPagingEnabled && allow_server_paging; }
 132                 }
 133 #endif
 134
 135                 public bool IsFirstPage {
 136                         get {
 137                                 if (!allow_paging)
 138                                         return true;
 139
 140                                 return current_page_index == 0;
 141                         }
 142                 }
 143
 144                 public bool IsLastPage {
 145                         get {
 146                                 if (!allow_paging || page_size == 0)
 147                                         return true;
 148
 149                                 return  (current_page_index == (PageCount - 1));
 150                         }
 151                 }
 152
 153                 public bool IsPagingEnabled {
 154                         get { return (allow_paging && page_size != 0); }
 155                 }
 156
 157                 public bool IsReadOnly {
 158                         get { return false; } // as documented
 159                 }
 160
 161                 public bool IsSynchronized {
 162                         get { return false; } // as documented
 163                 }
 164
 165                 public int PageCount {
 166                         get {
 167                                 if (source == null)
 168                                         return 0;
 169
 170                                 if (!IsPagingEnabled || DataSourceCount == 0 || page_size == 0)
 171                                         return 1;
 172
 173                                 return (DataSourceCount + page_size - 1) / page_size;
 174                         }
 175                 }
 176
 177                 public int PageSize {
 178                         get { return page_size; }
 179                         set { page_size = value; }
 180                 }
 181
 182                 public object SyncRoot {
 183                         get { return this; }
 184                 }
 185
 186                 public int VirtualCount {
 187                         get { return virtual_count; }
 188                         set { virtual_count = value; }
 189                 }
 190 #if NET_2_0
 191                 public bool AllowServerPaging {
 192                         get {
 193                                 return allow_server_paging;
 194                         }
 195                         set {
 196                                 allow_server_paging = value;
 197                                 // AllowCustomPaging and AllowServerPaging are mutually exclusive
 198                                 if (allow_server_paging)
 199                                         allow_custom_paging = false;
 200                         }
 201                 }
 202 #endif
 203
 204                 public void CopyTo (Array array, int index)
 205                 {
 206                         foreach (object o in source)
 207                                 array.SetValue (o, index++);
 208                 }
 209
 210                 public IEnumerator GetEnumerator ()
 211                 {
 212                         // IList goes first, as it implements ICollection
 213                         IList list = source as IList;
 214                         int first = 0;
 215                         int count;
 216                         int limit;
 217                         if (list != null) {
 218                                 first = FirstIndexInPage;
 219                                 count = ((ICollection) source).Count;
 220                                 limit = ((first + page_size) > count) ? (count - first) : page_size;
 221                                 return GetListEnum (list, first, first + limit);
 222                         }
 223
 224                         ICollection col = source as ICollection;
 225                         if (col != null) {
 226                                 first = FirstIndexInPage;
 227                                 count = col.Count;
 228                                 limit = ((first + page_size) > count) ? (count - first) : page_size;
 229                                 return GetEnumeratorEnum (col.GetEnumerator (), first, first + page_size);
 230                         }
 231
 232                         return source.GetEnumerator ();
 233                 }
 234
 235                 public PropertyDescriptorCollection GetItemProperties (PropertyDescriptor [] list_accessors)
 236                 {
 237                         ITypedList typed = source as ITypedList;
 238                         if (typed == null)
 239                                 return null;
 240                         return typed.GetItemProperties (list_accessors);
 241                 }
 242
 243                 public string GetListName (PropertyDescriptor [] list_accessors)
 244                 {
 245                         return String.Empty; // as documented
 246                 }
 247
 248                 private IEnumerator GetListEnum (IList list, int start, int end)
 249                 {
 250                         if (!AllowPaging)
 251                                 end = list.Count;
 252                         else if (start >= list.Count)
 253                                 yield break;
 254
 255                         for (int i = start; i < end; i++)
 256                                 yield return list [i];
 257                 }
 258
 259                 private IEnumerator GetEnumeratorEnum (IEnumerator e, int start, int end)
 260                 {
 261                         for (int i = 0; i < start; i++)
 262                                 e.MoveNext ();
 263                         for (int i = start; (!allow_paging || i < end) && e.MoveNext (); i++)
 264                                 yield return e.Current;
 265                 }
 266         }
 267 }
 268