mcs/class/System.Data.Linq/src/DbLinq/Data/Linq/Implementation/EntityTracker.cs

   1 #region MIT license\r
   2 // \r
   3 // MIT license\r
   4 //\r
   5 // Copyright (c) 2007-2008 Jiri Moudry, Pascal Craponne\r
   6 // \r
   7 // Permission is hereby granted, free of charge, to any person obtaining a copy\r
   8 // of this software and associated documentation files (the "Software"), to deal\r
   9 // in the Software without restriction, including without limitation the rights\r
  10 // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell\r
  11 // copies of the Software, and to permit persons to whom the Software is\r
  12 // furnished to do so, subject to the following conditions:\r
  13 // \r
  14 // The above copyright notice and this permission notice shall be included in\r
  15 // all copies or substantial portions of the Software.\r
  16 // \r
  17 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR\r
  18 // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,\r
  19 // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE\r
  20 // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER\r
  21 // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,\r
  22 // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN\r
  23 // THE SOFTWARE.\r
  24 // \r
  25 #endregion\r
  26 \r
  27 using System;\r
  28 using System.Collections.Generic;\r
  29 using System.Linq;\r
  30 \r
  31 #if MONO_STRICT\r
  32 using System.Data.Linq.Identity;\r
  33 #else\r
  34 using DbLinq.Data.Linq.Identity;\r
  35 #endif\r
  36 \r
  37 #if MONO_STRICT\r
  38 namespace System.Data.Linq.Implementation\r
  39 #else\r
  40 namespace DbLinq.Data.Linq.Implementation\r
  41 #endif\r
  42 {\r
  43     /// <summary>\r
  44     /// List of entities, with their corresponding state (to insert, to watch, to delete)\r
  45     /// </summary>\r
  46     internal class EntityTracker : IEntityTracker\r
  47     {\r
  48         /// <summary>\r
  49         /// Entities being watched\r
  50         /// </summary>\r
  51         private readonly List<EntityTrack> entities = new List<EntityTrack>();\r
  52 \r
  53         /// <summary>\r
  54         /// Entities currently being watched and to be updated\r
  55         /// </summary>\r
  56         private readonly IDictionary<IdentityKey, EntityTrack> entitiesByKey = new Dictionary<IdentityKey, EntityTrack>();\r
  57 \r
  58         /// <summary>\r
  59         /// Finds an entity tracking info by object reference\r
  60         /// </summary>\r
  61         /// <param name="entity"></param>\r
  62         /// <returns></returns>\r
  63         private EntityTrack FindByReference(object entity)\r
  64         {\r
  65             //    return (from e in entities where e.Entity == entity select e).FirstOrDefault();\r
  66             return this.entities.Find(e => object.ReferenceEquals(entity, e.Entity));\r
  67         }\r
  68 \r
  69         /// <summary>\r
  70         /// Finds entity by key (PK)\r
  71         /// </summary>\r
  72         /// <param name="identityKey"></param>\r
  73         /// <returns></returns>\r
  74         public EntityTrack FindByIdentity(IdentityKey identityKey)\r
  75         {\r
  76             EntityTrack entityTrack;\r
  77             entitiesByKey.TryGetValue(identityKey, out entityTrack);\r
  78             return entityTrack;\r
  79         }\r
  80 \r
  81         /// <summary>\r
  82         /// Returns true if the list contains the entity\r
  83         /// </summary>\r
  84         /// <param name="entity"></param>\r
  85         /// <returns></returns>\r
  86         public bool ContainsReference(object entity)\r
  87         {\r
  88             return FindByReference(entity) != null;\r
  89         }\r
  90 \r
  91         /// <summary>\r
  92         /// Registers an entity to be inserted\r
  93         /// </summary>\r
  94         /// <param name="entity"></param>\r
  95         public void RegisterToInsert(object entity)\r
  96         {\r
  97             if (entity == null)\r
  98                 throw new ArgumentNullException("entity");\r
  99 \r
 100             var entityTrack = FindByReference(entity);\r
 101             if (entityTrack == null)\r
 102             {\r
 103                 entityTrack = new EntityTrack(entity, EntityState.ToInsert);\r
 104                 entities.Add(entityTrack);\r
 105             }\r
 106             else\r
 107             {\r
 108                 switch (entityTrack.EntityState)\r
 109                 {\r
 110                 // if already registered for insert/update, then this is an error\r
 111                 case EntityState.ToInsert:\r
 112                 case EntityState.ToWatch:\r
 113                     throw new InvalidOperationException();\r
 114                 // whenever the object is registered for deletion, the fact of\r
 115                 // registering it for insertion sets it back to watch\r
 116                 case EntityState.ToDelete:\r
 117                     entityTrack.EntityState = EntityState.ToWatch;\r
 118                     entitiesByKey[entityTrack.IdentityKey] = entityTrack;\r
 119                     break;\r
 120                 default:\r
 121                     throw new ArgumentOutOfRangeException();\r
 122                 }\r
 123             }\r
 124         }\r
 125 \r
 126         /// <summary>\r
 127         /// Registers an entity to be watched\r
 128         /// </summary>\r
 129         /// <param name="entity"></param>\r
 130         /// <param name="identityKey"></param>\r
 131         public void RegisterToWatch(object entity, IdentityKey identityKey)\r
 132         {\r
 133             var entityTrack = FindByReference(entity);\r
 134             if (entityTrack == null)\r
 135             {\r
 136                 entityTrack = new EntityTrack(entity, EntityState.ToWatch) { IdentityKey = identityKey };\r
 137                 entities.Add(entityTrack);\r
 138                 entitiesByKey[identityKey] = entityTrack;\r
 139             }\r
 140             else\r
 141             {\r
 142                 // changes the state of the current entity\r
 143                 switch (entityTrack.EntityState)\r
 144                 {\r
 145                 case EntityState.ToInsert:\r
 146                     entityTrack.EntityState = EntityState.ToWatch;\r
 147                     entityTrack.IdentityKey = identityKey;\r
 148                     entitiesByKey[identityKey] = entityTrack;\r
 149                     break;\r
 150                 // watched entities should not be registered again\r
 151                 case EntityState.ToWatch:\r
 152                 case EntityState.ToDelete:\r
 153                     throw new InvalidOperationException();\r
 154                 default:\r
 155                     throw new ArgumentOutOfRangeException();\r
 156                 }\r
 157             }\r
 158         }\r
 159 \r
 160         /// <summary>\r
 161         /// Registers entity to be deleted\r
 162         /// </summary>\r
 163         /// <param name="entity"></param>\r
 164         public void RegisterToDelete(object entity)\r
 165         {\r
 166             if (entity == null)\r
 167                 throw new ArgumentNullException("entity");\r
 168 \r
 169             var entityTrack = FindByReference(entity);\r
 170             if (entityTrack == null)\r
 171             {\r
 172                 entityTrack = new EntityTrack(entity, EntityState.ToDelete);\r
 173                 entities.Add(entityTrack);\r
 174             }\r
 175             else\r
 176             {\r
 177                 // changes the state of the current entity\r
 178                 switch (entityTrack.EntityState)\r
 179                 {\r
 180                 // if entity was to be inserted, we just remove it from the list\r
 181                 // as if it never came here\r
 182                 case EntityState.ToInsert:\r
 183                     entities.Remove(entityTrack);\r
 184                     break;\r
 185                 // watched entities are registered to be removed\r
 186                 case EntityState.ToWatch:\r
 187                     entityTrack.EntityState = EntityState.ToDelete;\r
 188                     entitiesByKey.Remove(entityTrack.IdentityKey);\r
 189                     break;\r
 190                 case EntityState.ToDelete:\r
 191                     throw new InvalidOperationException();\r
 192                 default:\r
 193                     throw new ArgumentOutOfRangeException();\r
 194                 }\r
 195             }\r
 196         }\r
 197 \r
 198         /// <summary>\r
 199         /// Unregisters the entity after deletion\r
 200         /// </summary>\r
 201         /// <param name="entity"></param>\r
 202         public void RegisterDeleted(object entity)\r
 203         {\r
 204             // TODO: we could require an index\r
 205             var entityTrack = FindByReference(entity);\r
 206             if (entityTrack == null)\r
 207             {\r
 208                 throw new ArgumentException("entity");\r
 209             }\r
 210             // changes the state of the current entity\r
 211             switch (entityTrack.EntityState)\r
 212             {\r
 213             case EntityState.ToDelete:\r
 214                 entities.Remove(entityTrack);\r
 215                 break;\r
 216             case EntityState.ToInsert:\r
 217             case EntityState.ToWatch:\r
 218                 throw new InvalidOperationException();\r
 219             default:\r
 220                 throw new ArgumentOutOfRangeException();\r
 221             }\r
 222         }\r
 223 \r
 224         /// <summary>\r
 225         /// Enumerates all registered entities\r
 226         /// </summary>\r
 227         /// <returns></returns>\r
 228         public IEnumerable<EntityTrack> EnumerateAll()\r
 229         {\r
 230             return entities;\r
 231         }\r
 232     }\r
 233 }\r