class/System.Runtime.Serialization/System.Runtime.Serialization/KnownTypeCollection.cs

   1 //
   2 // KnownTypeCollection.cs
   3 //
   4 // Author:
   5 //      Atsushi Enomoto <atsushi@ximian.com>
   6 //
   7 // Copyright (C) 2005 Novell, Inc.  http://www.novell.com
   8 //
   9 // Permission is hereby granted, free of charge, to any person obtaining
  10 // a copy of this software and associated documentation files (the
  11 // "Software"), to deal in the Software without restriction, including
  12 // without limitation the rights to use, copy, modify, merge, publish,
  13 // distribute, sublicense, and/or sell copies of the Software, and to
  14 // permit persons to whom the Software is furnished to do so, subject to
  15 // the following conditions:
  16 //
  17 // The above copyright notice and this permission notice shall be
  18 // included in all copies or substantial portions of the Software.
  19 //
  20 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  21 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  22 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  23 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  24 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  25 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  26 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  27 //
  28 #if NET_2_0
  29 using System;
  30 using System.Collections;
  31 using System.Collections.Generic;
  32 using System.Collections.ObjectModel;
  33 using System.Linq;
  34 using System.Reflection;
  35 using System.Xml;
  36 using System.Xml.Schema;
  37
  38 using QName = System.Xml.XmlQualifiedName;
  39 using System.Xml.Serialization;
  40
  41 namespace System.Runtime.Serialization
  42 {
  43 /*
  44         XmlFormatter implementation design inference:
  45
  46         type definitions:
  47         - No XML Schema types are directly used. There are some maps from
  48           xs:blahType to ms:blahType where the namespaceURI for prefix "ms" is
  49           "http://schemas.microsoft.com/2003/10/Serialization/" .
  50
  51         serializable types:
  52         - An object being serialized 1) must be of type System.Object, or
  53           2) must be null, or 3) must have either a [DataContract] attribute
  54           or a [Serializable] attribute to be serializable.
  55         - When the object is either of type System.Object or null, then the
  56           XML type is "anyType".
  57         - When the object is [Serializable], then the runtime-serialization
  58           compatible object graph is written.
  59         - Otherwise the serialization is based on contract attributes.
  60           ([Serializable] takes precedence).
  61
  62         type derivation:
  63         - For type A to be serializable, the base type B of A must be
  64           serializable.
  65         - If a type which is [Serializable] and whose base type has a
  66           [DataContract], then for base type members [DataContract] is taken.
  67         - It is vice versa i.e. if the base type is [Serializable] and the
  68           derived type has a [DataContract], then [Serializable] takes place
  69           for base members.
  70
  71         known type collection:
  72         - It internally manages mapping store keyed by contract QNames.
  73           KnownTypeCollection.Add() checks if the same QName contract already
  74           exists (and raises InvalidOperationException if required).
  75
  76 */
  77         internal static class TypeExtensions
  78         {
  79                 public static T GetCustomAttribute<T> (this Type type, bool inherit)
  80                 {
  81                         var arr = type.GetCustomAttributes (typeof (T), inherit);
  82                         return arr != null && arr.Length == 1 ? (T) arr [0] : default (T);
  83                 }
  84         }
  85
  86         internal sealed class KnownTypeCollection : Collection<Type>
  87         {
  88                 internal const string MSSimpleNamespace =
  89                         "http://schemas.microsoft.com/2003/10/Serialization/";
  90                 internal const string MSArraysNamespace =
  91                         "http://schemas.microsoft.com/2003/10/Serialization/Arrays";
  92                 internal const string DefaultClrNamespaceBase =
  93                         "http://schemas.datacontract.org/2004/07/";
  94
  95                 static QName any_type, bool_type,
  96                         byte_type, date_type, decimal_type, double_type,
  97                         float_type, string_type,
  98                         short_type, int_type, long_type,
  99                         ubyte_type, ushort_type, uint_type, ulong_type,
 100                         // non-TypeCode
 101                         any_uri_type, base64_type, duration_type, qname_type,
 102                         // custom in ms nsURI schema
 103                         char_type, guid_type,
 104                         // not in ms nsURI schema
 105                         dbnull_type;
 106
 107                 static KnownTypeCollection ()
 108                 {
 109                         //any_type, bool_type,  byte_type, date_type, decimal_type, double_type,        float_type, string_type,
 110                         // short_type, int_type, long_type,     ubyte_type, ushort_type, uint_type, ulong_type,
 111                         //      any_uri_type, base64_type, duration_type, qname_type,
 112                         //      char_type, guid_type,   dbnull_type;
 113                         string s = MSSimpleNamespace;
 114                         any_type = new QName ("anyType", s);
 115                         any_uri_type = new QName ("anyURI", s);
 116                         bool_type = new QName ("boolean", s);
 117                         base64_type = new QName ("base64Binary", s);
 118                         date_type = new QName ("dateTime", s);
 119                         duration_type = new QName ("duration", s);
 120                         qname_type = new QName ("QName", s);
 121                         decimal_type = new QName ("decimal", s);
 122                         double_type = new QName ("double", s);
 123                         float_type = new QName ("float", s);
 124                         byte_type = new QName ("byte", s);
 125                         short_type = new QName ("short", s);
 126                         int_type = new QName ("int", s);
 127                         long_type = new QName ("long", s);
 128                         ubyte_type = new QName ("unsignedByte", s);
 129                         ushort_type = new QName ("unsignedShort", s);
 130                         uint_type = new QName ("unsignedInt", s);
 131                         ulong_type = new QName ("unsignedLong", s);
 132                         string_type = new QName ("string", s);
 133                         guid_type = new QName ("guid", s);
 134                         char_type = new QName ("char", s);
 135
 136                         dbnull_type = new QName ("DBNull", MSSimpleNamespace + "System");
 137                 }
 138
 139                 // FIXME: find out how QName and guid are processed
 140
 141                 internal QName GetXmlName (Type type)
 142                 {
 143                         SerializationMap map = FindUserMap (type);
 144                         if (map != null)
 145                                 return map.XmlName;
 146                         return GetPredefinedTypeName (type);
 147                 }
 148
 149                 internal static QName GetPredefinedTypeName (Type type)
 150                 {
 151                         QName name = GetPrimitiveTypeName (type);
 152                         if (name != QName.Empty)
 153                                 return name;
 154                         if (type == typeof (DBNull))
 155                                 return dbnull_type;
 156                         return QName.Empty;
 157                 }
 158
 159                 internal static QName GetPrimitiveTypeName (Type type)
 160                 {
 161                         if (type.IsGenericType && type.GetGenericTypeDefinition () == typeof (Nullable<>))
 162                                 return GetPrimitiveTypeName (type.GetGenericArguments () [0]);
 163
 164                         if (type.IsEnum)
 165                                 return QName.Empty;
 166
 167                         switch (Type.GetTypeCode (type)) {
 168                         case TypeCode.Object: // other than System.Object
 169                         case TypeCode.DBNull: // it is natively mapped, but not in ms serialization namespace.
 170                         case TypeCode.Empty:
 171                         default:
 172                                 if (type == typeof (object))
 173                                         return any_type;
 174                                 if (type == typeof (Guid))
 175                                         return guid_type;
 176                                 if (type == typeof (TimeSpan))
 177                                         return duration_type;
 178                                 if (type == typeof (byte []))
 179                                         return base64_type;
 180                                 if (type == typeof (Uri))
 181                                         return any_uri_type;
 182                                 return QName.Empty;
 183                         case TypeCode.Boolean:
 184                                 return bool_type;
 185                         case TypeCode.Byte:
 186                                 return ubyte_type;
 187                         case TypeCode.Char:
 188                                 return char_type;
 189                         case TypeCode.DateTime:
 190                                 return date_type;
 191                         case TypeCode.Decimal:
 192                                 return decimal_type;
 193                         case TypeCode.Double:
 194                                 return double_type;
 195                         case TypeCode.Int16:
 196                                 return short_type;
 197                         case TypeCode.Int32:
 198                                 return int_type;
 199                         case TypeCode.Int64:
 200                                 return long_type;
 201                         case TypeCode.SByte:
 202                                 return byte_type;
 203                         case TypeCode.Single:
 204                                 return float_type;
 205                         case TypeCode.String:
 206                                 return string_type;
 207                         case TypeCode.UInt16:
 208                                 return ushort_type;
 209                         case TypeCode.UInt32:
 210                                 return uint_type;
 211                         case TypeCode.UInt64:
 212                                 return ulong_type;
 213                         }
 214                 }
 215
 216                 internal static string PredefinedTypeObjectToString (object obj)
 217                 {
 218                         Type type = obj.GetType ();
 219                         switch (Type.GetTypeCode (type)) {
 220                         case TypeCode.Object: // other than System.Object
 221                         case TypeCode.Empty:
 222                         default:
 223                                 if (type == typeof (object))
 224                                         return String.Empty;
 225                                 if (type == typeof (Guid))
 226                                         return XmlConvert.ToString ((Guid) obj);
 227                                 if (type == typeof (TimeSpan))
 228                                         return XmlConvert.ToString ((TimeSpan) obj);
 229                                 if (type == typeof (byte []))
 230                                         return Convert.ToBase64String ((byte []) obj);
 231                                 if (type == typeof (Uri))
 232                                         return ((Uri) obj).ToString ();
 233                                 throw new Exception ("Internal error: missing predefined type serialization for type " + type.FullName);
 234                         case TypeCode.DBNull: // predefined, but not primitive
 235                                 return String.Empty;
 236                         case TypeCode.Boolean:
 237                                 return XmlConvert.ToString ((bool) obj);
 238                         case TypeCode.Byte:
 239                                 return XmlConvert.ToString ((int)((byte) obj));
 240                         case TypeCode.Char:
 241                                 return XmlConvert.ToString ((uint) (char) obj);
 242                         case TypeCode.DateTime:
 243                                 return XmlConvert.ToString ((DateTime) obj, XmlDateTimeSerializationMode.RoundtripKind);
 244                         case TypeCode.Decimal:
 245                                 return XmlConvert.ToString ((decimal) obj);
 246                         case TypeCode.Double:
 247                                 return XmlConvert.ToString ((double) obj);
 248                         case TypeCode.Int16:
 249                                 return XmlConvert.ToString ((short) obj);
 250                         case TypeCode.Int32:
 251                                 return XmlConvert.ToString ((int) obj);
 252                         case TypeCode.Int64:
 253                                 return XmlConvert.ToString ((long) obj);
 254                         case TypeCode.SByte:
 255                                 return XmlConvert.ToString ((sbyte) obj);
 256                         case TypeCode.Single:
 257                                 return XmlConvert.ToString ((float) obj);
 258                         case TypeCode.String:
 259                                 return (string) obj;
 260                         case TypeCode.UInt16:
 261                                 return XmlConvert.ToString ((int) (ushort) obj);
 262                         case TypeCode.UInt32:
 263                                 return XmlConvert.ToString ((uint) obj);
 264                         case TypeCode.UInt64:
 265                                 return XmlConvert.ToString ((ulong) obj);
 266                         }
 267                 }
 268
 269                 // FIXME: xsd types and ms serialization types should be differentiated.
 270                 internal static Type GetPrimitiveTypeFromName (string name)
 271                 {
 272                         switch (name) {
 273                         case "anyURI":
 274                                 return typeof (Uri);
 275                         case "boolean":
 276                                 return typeof (bool);
 277                         case "base64Binary":
 278                                 return typeof (byte []);
 279                         case "dateTime":
 280                                 return typeof (DateTime);
 281                         case "duration":
 282                                 return typeof (TimeSpan);
 283                         case "QName":
 284                                 return typeof (QName);
 285                         case "decimal":
 286                                 return typeof (decimal);
 287                         case "double":
 288                                 return typeof (double);
 289                         case "float":
 290                                 return typeof (float);
 291                         case "byte":
 292                                 return typeof (sbyte);
 293                         case "short":
 294                                 return typeof (short);
 295                         case "int":
 296                                 return typeof (int);
 297                         case "long":
 298                                 return typeof (long);
 299                         case "unsignedByte":
 300                                 return typeof (byte);
 301                         case "unsignedShort":
 302                                 return typeof (ushort);
 303                         case "unsignedInt":
 304                                 return typeof (uint);
 305                         case "unsignedLong":
 306                                 return typeof (ulong);
 307                         case "string":
 308                                 return typeof (string);
 309                         case "anyType":
 310                                 return typeof (object);
 311                         case "guid":
 312                                 return typeof (Guid);
 313                         case "char":
 314                                 return typeof (char);
 315                         default:
 316                                 return null;
 317                         }
 318                 }
 319
 320
 321                 internal static object PredefinedTypeStringToObject (string s,
 322                         string name, XmlReader reader)
 323                 {
 324                         switch (name) {
 325                         case "anyURI":
 326                                 return new Uri(s,UriKind.RelativeOrAbsolute);
 327                         case "boolean":
 328                                 return XmlConvert.ToBoolean (s);
 329                         case "base64Binary":
 330                                 return Convert.FromBase64String (s);
 331                         case "dateTime":
 332                                 return XmlConvert.ToDateTime (s, XmlDateTimeSerializationMode.RoundtripKind);
 333                         case "duration":
 334                                 return XmlConvert.ToTimeSpan (s);
 335                         case "QName":
 336                                 int idx = s.IndexOf (':');
 337                                 string l = idx < 0 ? s : s.Substring (idx + 1);
 338                                 return idx < 0 ? new QName (l) :
 339                                         new QName (l, reader.LookupNamespace (
 340                                                 s.Substring (0, idx)));
 341                         case "decimal":
 342                                 return XmlConvert.ToDecimal (s);
 343                         case "double":
 344                                 return XmlConvert.ToDouble (s);
 345                         case "float":
 346                                 return XmlConvert.ToSingle (s);
 347                         case "byte":
 348                                 return XmlConvert.ToSByte (s);
 349                         case "short":
 350                                 return XmlConvert.ToInt16 (s);
 351                         case "int":
 352                                 return XmlConvert.ToInt32 (s);
 353                         case "long":
 354                                 return XmlConvert.ToInt64 (s);
 355                         case "unsignedByte":
 356                                 return XmlConvert.ToByte (s);
 357                         case "unsignedShort":
 358                                 return XmlConvert.ToUInt16 (s);
 359                         case "unsignedInt":
 360                                 return XmlConvert.ToUInt32 (s);
 361                         case "unsignedLong":
 362                                 return XmlConvert.ToUInt64 (s);
 363                         case "string":
 364                                 return s;
 365                         case "guid":
 366                                 return XmlConvert.ToGuid (s);
 367                         case "anyType":
 368                                 return s;
 369                         case "char":
 370                                 return (char) XmlConvert.ToUInt32 (s);
 371                         default:
 372                                 throw new Exception ("Unanticipated primitive type: " + name);
 373                         }
 374                 }
 375
 376                 List<SerializationMap> contracts = new List<SerializationMap> ();
 377
 378                 public KnownTypeCollection ()
 379                 {
 380                 }
 381
 382                 protected override void ClearItems ()
 383                 {
 384                         base.Clear ();
 385                 }
 386
 387                 protected override void InsertItem (int index, Type type)
 388                 {
 389                         if (TryRegister (type))
 390                                 base.InsertItem (index, type);
 391                 }
 392
 393                 // FIXME: it could remove other types' dependencies.
 394                 protected override void RemoveItem (int index)
 395                 {
 396                         Type t = base [index];
 397                         List<SerializationMap> l = new List<SerializationMap> ();
 398                         foreach (SerializationMap m in contracts) {
 399                                 if (m.RuntimeType == t)
 400                                         l.Add (m);
 401                         }
 402                         foreach (SerializationMap m in l) {
 403                                 contracts.Remove (m);
 404                                 base.RemoveItem (index);
 405                         }
 406                 }
 407
 408                 protected override void SetItem (int index, Type type)
 409                 {
 410                         if (index == Count)
 411                                 InsertItem (index, type);
 412                         else {
 413                                 RemoveItem (index);
 414                                 if (TryRegister (type))
 415                                         base.InsertItem (index - 1, type);
 416                         }
 417                 }
 418
 419                 internal SerializationMap FindUserMap (QName qname)
 420                 {
 421                         for (int i = 0; i < contracts.Count; i++)
 422                                 if (qname == contracts [i].XmlName)
 423                                         return contracts [i];
 424                         return null;
 425                 }
 426
 427                 internal Type GetSerializedType (Type type)
 428                 {
 429                         Type element = GetCollectionElementType (type);
 430                         if (element == null)
 431                                 return type;
 432                         QName name = GetQName (type);
 433                         var map = FindUserMap (name);
 434                         if (map != null)
 435                                 return map.RuntimeType;
 436                         return type;
 437                 }
 438
 439                 internal SerializationMap FindUserMap (Type type)
 440                 {
 441                         for (int i = 0; i < contracts.Count; i++)
 442                                 if (type == contracts [i].RuntimeType)
 443                                         return contracts [i];
 444                         return null;
 445                 }
 446
 447                 internal QName GetQName (Type type)
 448                 {
 449                         SerializationMap map = FindUserMap (type);
 450                         if (map != null)
 451                                 // already mapped.
 452                                 return map.XmlName;
 453                         return GetStaticQName (type);
 454                 }
 455
 456                 public static QName GetStaticQName (Type type)
 457                 {
 458                         if (IsPrimitiveNotEnum (type))
 459                                 return GetPrimitiveTypeName (type);
 460
 461                         if (type.IsEnum)
 462                                 return GetEnumQName (type);
 463
 464                         QName qname = GetContractQName (type);
 465                         if (qname != null)
 466                                 return qname;
 467
 468                         if (type.GetInterface ("System.Xml.Serialization.IXmlSerializable") != null)
 469                                 //FIXME: Reusing GetSerializableQName here, since we just
 470                                 //need name of the type..
 471                                 return GetSerializableQName (type);
 472
 473                         qname = GetCollectionContractQName (type);
 474                         if (qname != null)
 475                                 return qname;
 476
 477                         Type element = GetCollectionElementType (type);
 478                         if (element != null)
 479                                 return GetCollectionQName (element);
 480
 481                         if (GetAttribute<SerializableAttribute> (type) != null)
 482                                 return GetSerializableQName (type);
 483
 484                         // default type map - still uses GetContractQName().
 485                         return GetContractQName (type, null, null);
 486                 }
 487
 488                 internal static QName GetContractQName (Type type)
 489                 {
 490                         var a = GetAttribute<DataContractAttribute> (type);
 491                         return a == null ? null : GetContractQName (type, a.Name, a.Namespace);
 492                 }
 493
 494                 static QName GetCollectionContractQName (Type type)
 495                 {
 496                         var a = GetAttribute<CollectionDataContractAttribute> (type);
 497                         return a == null ? null : GetContractQName (type, a.Name, a.Namespace);
 498                 }
 499
 500                 static QName GetContractQName (Type type, string name, string ns)
 501                 {
 502                         if (name == null)
 503                                 name = GetDefaultName (type);
 504                         if (ns == null)
 505                                 ns = GetDefaultNamespace (type);
 506                         return new QName (name, ns);
 507                 }
 508
 509                 static QName GetEnumQName (Type type)
 510                 {
 511                         string name = null, ns = null;
 512
 513                         if (!type.IsEnum)
 514                                 return null;
 515
 516                         var dca = GetAttribute<DataContractAttribute> (type);
 517
 518                         if (dca != null) {
 519                                 ns = dca.Namespace;
 520                                 name = dca.Name;
 521                         }
 522
 523                         if (ns == null)
 524                                 ns = GetDefaultNamespace (type);
 525
 526                         if (name == null)
 527                                 name = type.Namespace == null ? type.Name : type.FullName.Substring (type.Namespace.Length + 1).Replace ('+', '.');
 528
 529                         return new QName (name, ns);
 530                 }
 531
 532                 internal static string GetDefaultName (Type type)
 533                 {
 534                         // FIXME: there could be decent ways to get
 535                         // the same result...
 536                         string name = type.Namespace == null || type.Namespace.Length == 0 ? type.Name : type.FullName.Substring (type.Namespace.Length + 1).Replace ('+', '.');
 537                         if (type.IsGenericType) {
 538                                 name = name.Substring (0, name.IndexOf ('`')) + "Of";
 539                                 foreach (var t in type.GetGenericArguments ())
 540                                         name += t.Name; // FIXME: check namespaces too
 541                         }
 542                         return name;
 543                 }
 544
 545                 internal static string GetDefaultNamespace (Type type)
 546                 {
 547                         foreach (ContractNamespaceAttribute a in type.Assembly.GetCustomAttributes (typeof (ContractNamespaceAttribute), true))
 548                                 if (a.ClrNamespace == type.Namespace)
 549                                         return a.ContractNamespace;
 550                         return DefaultClrNamespaceBase + type.Namespace;
 551                 }
 552
 553                 static QName GetCollectionQName (Type element)
 554                 {
 555                         QName eqname = GetStaticQName (element);
 556
 557                         string ns = eqname.Namespace;
 558                         if (eqname.Namespace == MSSimpleNamespace)
 559                                 //Arrays of Primitive types
 560                                 ns = MSArraysNamespace;
 561
 562                         return new QName (
 563                                 "ArrayOf" + XmlConvert.EncodeLocalName (eqname.Name),
 564                                 ns);
 565                 }
 566
 567                 static QName GetSerializableQName (Type type)
 568                 {
 569                         string xmlName = type.Name;
 570                         if (type.IsGenericType) {
 571                                 xmlName = xmlName.Substring (0, xmlName.IndexOf ('`')) + "Of";
 572                                 foreach (var t in type.GetGenericArguments ())
 573                                         xmlName += GetStaticQName (t).Name; // FIXME: check namespaces too
 574                         }
 575                         string xmlNamespace = GetDefaultNamespace (type);
 576                         var x = GetAttribute<XmlRootAttribute> (type);
 577                         if (x != null) {
 578                                 xmlName = x.ElementName;
 579                                 xmlNamespace = x.Namespace;
 580                         }
 581                         return new QName (XmlConvert.EncodeLocalName (xmlName), xmlNamespace);
 582                 }
 583
 584                 static bool IsPrimitiveNotEnum (Type type)
 585                 {
 586                         if (type.IsEnum)
 587                                 return false;
 588                         if (Type.GetTypeCode (type) != TypeCode.Object) // explicitly primitive
 589                                 return true;
 590                         if (type == typeof (Guid) || type == typeof (object) || type == typeof(TimeSpan) || type == typeof(byte[]) || type==typeof(Uri)) // special primitives
 591                                 return true;
 592                         // nullable
 593                         if (type.IsGenericType && type.GetGenericTypeDefinition () == typeof (Nullable<>))
 594                                 return IsPrimitiveNotEnum (type.GetGenericArguments () [0]);
 595                         return false;
 596                 }
 597
 598                 internal bool TryRegister (Type type)
 599                 {
 600                         // exclude predefined maps
 601                         if (IsPrimitiveNotEnum (type))
 602                                 return false;
 603
 604                         if (FindUserMap (type) != null)
 605                                 return false;
 606
 607                         if (RegisterEnum (type) != null)
 608                                 return true;
 609
 610                         if (RegisterDictionary (type) != null)
 611                                 return true;
 612
 613                         if (RegisterCollectionContract (type) != null)
 614                                 return true;
 615
 616                         if (RegisterContract (type) != null)
 617                                 return true;
 618
 619                         if (RegisterIXmlSerializable (type) != null)
 620                                 return true;
 621
 622                         if (RegisterCollection (type) != null)
 623                                 return true;
 624
 625                         if (GetAttribute<SerializableAttribute> (type) != null) {
 626                                 RegisterSerializable (type);
 627                                 return true;
 628                         }
 629
 630                         RegisterDefaultTypeMap (type);
 631                         return true;
 632                 }
 633
 634                 static Type GetCollectionElementType (Type type)
 635                 {
 636                         if (type.IsArray)
 637                                 return type.GetElementType ();
 638
 639                         Type [] ifaces = type.GetInterfaces ();
 640                         foreach (Type i in ifaces)
 641                                 if (i.IsGenericType && i.GetGenericTypeDefinition ().Equals (typeof (ICollection<>)))
 642                                         return i.GetGenericArguments () [0];
 643                         foreach (Type i in ifaces)
 644                                 if (i == typeof (IList))
 645                                         return typeof (object);
 646                         return null;
 647                 }
 648
 649                 internal static T GetAttribute<T> (ICustomAttributeProvider ap) where T : Attribute
 650                 {
 651                         object [] atts = ap.GetCustomAttributes (typeof (T), false);
 652                         return atts.Length == 0 ? null : (T) atts [0];
 653                 }
 654
 655                 private CollectionContractTypeMap RegisterCollectionContract (Type type)
 656                 {
 657                         var cdca = GetAttribute<CollectionDataContractAttribute> (type);
 658                         if (cdca == null)
 659                                 return null;
 660
 661                         Type element = GetCollectionElementType (type);
 662                         if (element == null)
 663                                 throw new InvalidOperationException (String.Format ("Type '{0}' is marked as collection contract, but it is not a collection", type));
 664
 665                         TryRegister (element); // must be registered before the name conflict check.
 666
 667                         QName qname = GetCollectionContractQName (type);
 668                         CheckStandardQName (qname);
 669                         if (FindUserMap (qname) != null)
 670                                 throw new InvalidOperationException (String.Format ("Failed to add type {0} to known type collection. There already is a registered type for XML name {1}", type, qname));
 671
 672                         var ret = new CollectionContractTypeMap (type, cdca, element, qname, this);
 673                         contracts.Add (ret);
 674                         return ret;
 675                 }
 676
 677                 private CollectionTypeMap RegisterCollection (Type type)
 678                 {
 679                         Type element = GetCollectionElementType (type);
 680                         if (element == null)
 681                                 return null;
 682
 683                         TryRegister (element);
 684
 685                         QName qname = GetCollectionQName (element);
 686
 687                         var map = FindUserMap (qname);
 688                         if (map != null) {
 689                                 var cmap = map as CollectionTypeMap;
 690                                 if (cmap == null || cmap.RuntimeType != type)
 691                                         throw new InvalidOperationException (String.Format ("Failed to add type {0} to known type collection. There already is a registered type for XML name {1}", type, qname));
 692                                 return cmap;
 693                         }
 694
 695                         CollectionTypeMap ret =
 696                                 new CollectionTypeMap (type, element, qname, this);
 697                         contracts.Add (ret);
 698                         return ret;
 699                 }
 700
 701                 static bool TypeImplementsIDictionary (Type type)
 702                 {
 703                         foreach (var iface in type.GetInterfaces ())
 704                                 if (iface == typeof (IDictionary) || (iface.IsGenericType && iface.GetGenericTypeDefinition () == typeof (IDictionary<,>)))
 705                                         return true;
 706
 707                         return false;
 708                 }
 709
 710                 // it also supports contract-based dictionary.
 711                 private DictionaryTypeMap RegisterDictionary (Type type)
 712                 {
 713                         if (!TypeImplementsIDictionary (type))
 714                                 return null;
 715
 716                         var cdca = GetAttribute<CollectionDataContractAttribute> (type);
 717
 718                         DictionaryTypeMap ret =
 719                                 new DictionaryTypeMap (type, cdca, this);
 720
 721                         if (FindUserMap (ret.XmlName) != null)
 722                                 throw new InvalidOperationException (String.Format ("Failed to add type {0} to known type collection. There already is a registered type for XML name {1}", type, ret.XmlName));
 723                         contracts.Add (ret);
 724
 725                         TryRegister (ret.KeyType);
 726                         TryRegister (ret.ValueType);
 727
 728                         return ret;
 729                 }
 730
 731                 private SerializationMap RegisterSerializable (Type type)
 732                 {
 733                         QName qname = GetSerializableQName (type);
 734
 735                         if (FindUserMap (qname) != null)
 736                                 throw new InvalidOperationException (String.Format ("There is already a registered type for XML name {0}", qname));
 737
 738                         SharedTypeMap ret = new SharedTypeMap (type, qname, this);
 739                         contracts.Add (ret);
 740                         ret.Initialize ();
 741                         return ret;
 742                 }
 743
 744                 private SerializationMap RegisterIXmlSerializable (Type type)
 745                 {
 746                         if (type.GetInterface ("System.Xml.Serialization.IXmlSerializable") == null)
 747                                 return null;
 748
 749                         QName qname = GetSerializableQName (type);
 750
 751                         if (FindUserMap (qname) != null)
 752                                 throw new InvalidOperationException (String.Format ("There is already a registered type for XML name {0}", qname));
 753
 754                         XmlSerializableMap ret = new XmlSerializableMap (type, qname, this);
 755                         contracts.Add (ret);
 756
 757                         return ret;
 758                 }
 759
 760                 void CheckStandardQName (QName qname)
 761                 {
 762                         switch (qname.Namespace) {
 763                         case XmlSchema.Namespace:
 764                         case XmlSchema.InstanceNamespace:
 765                         case MSSimpleNamespace:
 766                         case MSArraysNamespace:
 767                                 throw new InvalidOperationException (String.Format ("Namespace {0} is reserved and cannot be used for user serialization", qname.Namespace));
 768                         }
 769
 770                 }
 771
 772                 private SharedContractMap RegisterContract (Type type)
 773                 {
 774                         QName qname = GetContractQName (type);
 775                         if (qname == null)
 776                                 return null;
 777                         CheckStandardQName (qname);
 778                         if (FindUserMap (qname) != null)
 779                                 throw new InvalidOperationException (String.Format ("There is already a registered type for XML name {0}", qname));
 780
 781                         SharedContractMap ret = new SharedContractMap (type, qname, this);
 782                         contracts.Add (ret);
 783                         ret.Initialize ();
 784
 785                         object [] attrs = type.GetCustomAttributes (typeof (KnownTypeAttribute), true);
 786                         for (int i = 0; i < attrs.Length; i++) {
 787                                 KnownTypeAttribute kt = (KnownTypeAttribute) attrs [i];
 788                                 TryRegister (kt.Type);
 789                         }
 790
 791                         return ret;
 792                 }
 793
 794                 DefaultTypeMap RegisterDefaultTypeMap (Type type)
 795                 {
 796                         DefaultTypeMap ret = new DefaultTypeMap (type, this);
 797                         contracts.Add (ret);
 798                         return ret;
 799                 }
 800
 801                 private EnumMap RegisterEnum (Type type)
 802                 {
 803                         QName qname = GetEnumQName (type);
 804                         if (qname == null)
 805                                 return null;
 806
 807                         if (FindUserMap (qname) != null)
 808                                 throw new InvalidOperationException (String.Format ("There is already a registered type for XML name {0}", qname));
 809
 810                         EnumMap ret =
 811                                 new EnumMap (type, qname, this);
 812                         contracts.Add (ret);
 813                         return ret;
 814                 }
 815         }
 816 }
 817 #endif