mcs/class/System.Xaml/System.Xaml/XamlType.cs

   1 //
   2 // Copyright (C) 2010 Novell Inc. http://novell.com
   3 //
   4 // Permission is hereby granted, free of charge, to any person obtaining
   5 // a copy of this software and associated documentation files (the
   6 // "Software"), to deal in the Software without restriction, including
   7 // without limitation the rights to use, copy, modify, merge, publish,
   8 // distribute, sublicense, and/or sell copies of the Software, and to
   9 // permit persons to whom the Software is furnished to do so, subject to
  10 // the following conditions:
  11 //
  12 // The above copyright notice and this permission notice shall be
  13 // included in all copies or substantial portions of the Software.
  14 //
  15 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  16 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  17 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  18 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  19 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  20 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  21 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  22 //
  23 using System;
  24 using System.Collections;
  25 using System.Collections.Generic;
  26 using System.ComponentModel;
  27 using System.Linq;
  28 using System.Reflection;
  29 using System.Windows.Markup;
  30 using System.Xaml.Schema;
  31 using System.Xml.Serialization;
  32
  33 namespace System.Xaml
  34 {
  35         public class XamlType : IEquatable<XamlType>
  36         {
  37                 public XamlType (Type underlyingType, XamlSchemaContext schemaContext)
  38                         : this (underlyingType, schemaContext, null)
  39                 {
  40                 }
  41
  42 //              static readonly Type [] predefined_types = {
  43 //                              typeof (XData), typeof (Uri), typeof (TimeSpan), typeof (PropertyDefinition), typeof (MemberDefinition), typeof (Reference)
  44 //                      };
  45
  46                 public XamlType (Type underlyingType, XamlSchemaContext schemaContext, XamlTypeInvoker invoker)
  47                         : this (schemaContext, invoker)
  48                 {
  49                         if (underlyingType == null)
  50                                 throw new ArgumentNullException ("underlyingType");
  51                         type = underlyingType;
  52                         underlying_type = type;
  53
  54                         XamlType xt;
  55                         if (XamlLanguage.InitializingTypes) {
  56                                 // These are special. Only XamlLanguage members are with shorthand name.
  57                                 if (type == typeof (PropertyDefinition))
  58                                         Name = "Property";
  59                                 else if (type == typeof (MemberDefinition))
  60                                         Name = "Member";
  61                                 else
  62                                         Name = GetXamlName (type);
  63                                 PreferredXamlNamespace = XamlLanguage.Xaml2006Namespace;
  64                         } else if ((xt = XamlLanguage.AllTypes.FirstOrDefault (t => t.UnderlyingType == type)) != null) {
  65                                 Name = xt.Name;
  66                                 PreferredXamlNamespace = XamlLanguage.Xaml2006Namespace;
  67                         } else {
  68                                 Name = GetXamlName (type);
  69                                 PreferredXamlNamespace = String.Format ("clr-namespace:{0};assembly={1}", type.Namespace, type.Assembly.GetName ().Name);
  70                         }
  71                         if (type.IsGenericType) {
  72                                 TypeArguments = new List<XamlType> ();
  73                                 foreach (var gta in type.GetGenericArguments ())
  74                                         TypeArguments.Add (schemaContext.GetXamlType (gta));
  75                         }
  76                 }
  77
  78                 public XamlType (string unknownTypeNamespace, string unknownTypeName, IList<XamlType> typeArguments, XamlSchemaContext schemaContext)
  79                         : this (schemaContext, null)
  80                 {
  81                         if (unknownTypeNamespace == null)
  82                                 throw new ArgumentNullException ("unknownTypeNamespace");
  83                         if (unknownTypeName == null)
  84                                 throw new ArgumentNullException ("unknownTypeName");
  85                         if (schemaContext == null)
  86                                 throw new ArgumentNullException ("schemaContext");
  87
  88                         type = typeof (object);
  89                         Name = unknownTypeName;
  90                         PreferredXamlNamespace = unknownTypeNamespace;
  91                         TypeArguments = typeArguments != null && typeArguments.Count == 0 ? null : typeArguments;
  92                         explicit_ns = unknownTypeNamespace;
  93                 }
  94
  95                 protected XamlType (string typeName, IList<XamlType> typeArguments, XamlSchemaContext schemaContext)
  96                         : this (String.Empty, typeName, typeArguments, schemaContext)
  97                 {
  98                 }
  99
 100                 XamlType (XamlSchemaContext schemaContext, XamlTypeInvoker invoker)
 101                 {
 102                         if (schemaContext == null)
 103                                 throw new ArgumentNullException ("schemaContext");
 104                         SchemaContext = schemaContext;
 105                         this.invoker = invoker ?? new XamlTypeInvoker (this);
 106                 }
 107
 108                 Type type, underlying_type;
 109
 110                 string explicit_ns;
 111
 112                 // populated properties
 113                 XamlType base_type;
 114                 XamlTypeInvoker invoker;
 115
 116                 internal EventHandler<XamlSetMarkupExtensionEventArgs> SetMarkupExtensionHandler {
 117                         get { return LookupSetMarkupExtensionHandler (); }
 118                 }
 119
 120                 internal EventHandler<XamlSetTypeConverterEventArgs> SetTypeConverterHandler {
 121                         get { return LookupSetTypeConverterHandler (); }
 122                 }
 123
 124                 public IList<XamlType> AllowedContentTypes {
 125                         get { return LookupAllowedContentTypes (); }
 126                 }
 127
 128                 public XamlType BaseType {
 129                         get { return LookupBaseType (); }
 130                 }
 131
 132                 public bool ConstructionRequiresArguments {
 133                         get { return LookupConstructionRequiresArguments (); }
 134                 }
 135
 136                 public XamlMember ContentProperty {
 137                         get { return LookupContentProperty (); }
 138                 }
 139
 140                 public IList<XamlType> ContentWrappers {
 141                         get { return LookupContentWrappers (); }
 142                 }
 143
 144                 public XamlValueConverter<XamlDeferringLoader> DeferringLoader {
 145                         get { return LookupDeferringLoader (); }
 146                 }
 147
 148                 public XamlTypeInvoker Invoker {
 149                         get { return LookupInvoker (); }
 150                 }
 151
 152                 public bool IsAmbient {
 153                         get { return LookupIsAmbient (); }
 154                 }
 155
 156                 public bool IsArray {
 157                         get { return LookupCollectionKind () == XamlCollectionKind.Array; }
 158                 }
 159
 160                 // it somehow treats array as not a collection...
 161                 public bool IsCollection {
 162                         get { return LookupCollectionKind () == XamlCollectionKind.Collection; }
 163                 }
 164
 165                 public bool IsConstructible {
 166                         get { return LookupIsConstructible (); }
 167                 }
 168
 169                 public bool IsDictionary {
 170                         get { return LookupCollectionKind () == XamlCollectionKind.Dictionary; }
 171                 }
 172
 173                 public bool IsGeneric {
 174                         get { return type.IsGenericType; }
 175                 }
 176
 177                 public bool IsMarkupExtension {
 178                         get { return LookupIsMarkupExtension (); }
 179                 }
 180                 public bool IsNameScope {
 181                         get { return LookupIsNameScope (); }
 182                 }
 183                 public bool IsNameValid {
 184                         get { return XamlLanguage.IsValidXamlName (Name); }
 185                 }
 186
 187                 public bool IsNullable {
 188                         get { return LookupIsNullable (); }
 189                 }
 190
 191                 public bool IsPublic {
 192                         get { return LookupIsPublic (); }
 193                 }
 194
 195                 public bool IsUnknown {
 196                         get { return LookupIsUnknown (); }
 197                 }
 198
 199                 public bool IsUsableDuringInitialization {
 200                         get { return LookupUsableDuringInitialization (); }
 201                 }
 202
 203                 public bool IsWhitespaceSignificantCollection {
 204                         get { return LookupIsWhitespaceSignificantCollection (); }
 205                 }
 206
 207                 public bool IsXData {
 208                         get { return LookupIsXData (); }
 209                 }
 210
 211                 public XamlType ItemType {
 212                         get { return LookupItemType (); }
 213                 }
 214
 215                 public XamlType KeyType {
 216                         get { return LookupKeyType (); }
 217                 }
 218
 219                 public XamlType MarkupExtensionReturnType {
 220                         get { return LookupMarkupExtensionReturnType (); }
 221                 }
 222
 223                 public string Name { get; private set; }
 224
 225                 public string PreferredXamlNamespace { get; private set; }
 226
 227                 public XamlSchemaContext SchemaContext { get; private set; }
 228
 229                 public bool TrimSurroundingWhitespace {
 230                         get { return LookupTrimSurroundingWhitespace (); }
 231                 }
 232
 233                 public IList<XamlType> TypeArguments { get; private set; }
 234
 235                 public XamlValueConverter<TypeConverter> TypeConverter {
 236                         get { return LookupTypeConverter (); }
 237                 }
 238
 239                 public Type UnderlyingType {
 240                         get { return LookupUnderlyingType (); }
 241                 }
 242
 243                 public XamlValueConverter<ValueSerializer> ValueSerializer {
 244                         get { return LookupValueSerializer (); }
 245                 }
 246
 247                 internal string GetInternalXmlName ()
 248                 {
 249                         if (IsMarkupExtension && Name.EndsWith ("Extension", StringComparison.Ordinal))
 250                                 return Name.Substring (0, Name.Length - 9);
 251                         var stn = XamlLanguage.SpecialNames.FirstOrDefault (s => s.Type == this);
 252                         return stn != null ? stn.Name : Name;
 253                 }
 254
 255                 public static bool operator == (XamlType left, XamlType right)
 256                 {
 257                         return IsNull (left) ? IsNull (right) : left.Equals (right);
 258                 }
 259
 260                 static bool IsNull (XamlType a)
 261                 {
 262                         return Object.ReferenceEquals (a, null);
 263                 }
 264
 265                 public static bool operator != (XamlType left, XamlType right)
 266                 {
 267                         return !(left == right);
 268                 }
 269
 270                 public bool Equals (XamlType other)
 271                 {
 272                         // It does not compare XamlSchemaContext.
 273                         return !IsNull (other) &&
 274                                 UnderlyingType == other.UnderlyingType &&
 275                                 Name == other.Name &&
 276                                 PreferredXamlNamespace == other.PreferredXamlNamespace && TypeArguments.ListEquals (other.TypeArguments);
 277                 }
 278
 279                 public override bool Equals (object obj)
 280                 {
 281                         var a = obj as XamlType;
 282                         return Equals (a);
 283                 }
 284
 285                 public override int GetHashCode ()
 286                 {
 287                         if (UnderlyingType != null)
 288                                 return UnderlyingType.GetHashCode ();
 289                         int x = Name.GetHashCode () << 7 + PreferredXamlNamespace.GetHashCode ();
 290                         if (TypeArguments != null)
 291                                 foreach (var t in TypeArguments)
 292                                         x = t.GetHashCode () + x << 5;
 293                         return x;
 294                 }
 295
 296                 public override string ToString ()
 297                 {
 298                         return new XamlTypeName (this).ToString ();
 299                         //return String.IsNullOrEmpty (PreferredXamlNamespace) ? Name : String.Concat ("{", PreferredXamlNamespace, "}", Name);
 300                 }
 301
 302                 public virtual bool CanAssignTo (XamlType xamlType)
 303                 {
 304                         if (this.UnderlyingType == null)
 305                                 return xamlType == XamlLanguage.Object;
 306                         var ut = xamlType.UnderlyingType ?? typeof (object);
 307                         return ut.IsAssignableFrom (UnderlyingType);
 308                 }
 309
 310                 public XamlMember GetAliasedProperty (XamlDirective directive)
 311                 {
 312                         return LookupAliasedProperty (directive);
 313                 }
 314
 315                 public ICollection<XamlMember> GetAllAttachableMembers ()
 316                 {
 317                         return new List<XamlMember> (LookupAllAttachableMembers ());
 318                 }
 319
 320                 public ICollection<XamlMember> GetAllMembers ()
 321                 {
 322                         return new List<XamlMember> (LookupAllMembers ());
 323                 }
 324
 325                 public XamlMember GetAttachableMember (string name)
 326                 {
 327                         return LookupAttachableMember (name);
 328                 }
 329
 330                 public XamlMember GetMember (string name)
 331                 {
 332                         return LookupMember (name, true);
 333                 }
 334
 335                 public IList<XamlType> GetPositionalParameters (int parameterCount)
 336                 {
 337                         return LookupPositionalParameters (parameterCount);
 338                 }
 339
 340                 public virtual IList<string> GetXamlNamespaces ()
 341                 {
 342                         throw new NotImplementedException ();
 343                         /* this does not work like documented!
 344                         if (explicit_ns != null)
 345                                 return new string [] {explicit_ns};
 346                         var l = SchemaContext.GetAllXamlNamespaces ();
 347                         if (l != null)
 348                                 return new List<string> (l);
 349                         return new string [] {String.Empty};
 350                         */
 351                 }
 352
 353                 // lookups
 354
 355                 protected virtual XamlMember LookupAliasedProperty (XamlDirective directive)
 356                 {
 357                         if (directive == XamlLanguage.Key) {
 358                                 var a = this.GetCustomAttribute<DictionaryKeyPropertyAttribute> ();
 359                                 return a != null ? GetMember (a.Name) : null;
 360                         }
 361                         if (directive == XamlLanguage.Name) {
 362                                 var a = this.GetCustomAttribute<RuntimeNamePropertyAttribute> ();
 363                                 return a != null ? GetMember (a.Name) : null;
 364                         }
 365                         if (directive == XamlLanguage.Uid) {
 366                                 var a = this.GetCustomAttribute<UidPropertyAttribute> ();
 367                                 return a != null ? GetMember (a.Name) : null;
 368                         }
 369                         if (directive == XamlLanguage.Lang) {
 370                                 var a = this.GetCustomAttribute<XmlLangPropertyAttribute> ();
 371                                 return a != null ? GetMember (a.Name) : null;
 372                         }
 373                         return null;
 374                 }
 375
 376                 protected virtual IEnumerable<XamlMember> LookupAllAttachableMembers ()
 377                 {
 378                         if (UnderlyingType == null)
 379                                 return BaseType != null ? BaseType.GetAllAttachableMembers () : null;
 380                         return DoLookupAllAttachableMembers ();
 381                 }
 382
 383                 IEnumerable<XamlMember> DoLookupAllAttachableMembers ()
 384                 {
 385                         yield break; // FIXME: what to return here?
 386                 }
 387
 388                 static readonly XamlMember [] empty_array = new XamlMember [0];
 389
 390                 protected virtual IEnumerable<XamlMember> LookupAllMembers ()
 391                 {
 392                         if (UnderlyingType == null)
 393                                 return BaseType != null ? BaseType.GetAllMembers () : empty_array;
 394                         if (all_members_cache == null) {
 395                                 all_members_cache = new List<XamlMember> (DoLookupAllMembers ());
 396                                 all_members_cache.Sort (TypeExtensionMethods.CompareMembers);
 397                         }
 398                         return all_members_cache;
 399                 }
 400
 401                 List<XamlMember> all_members_cache;
 402
 403                 IEnumerable<XamlMember> DoLookupAllMembers ()
 404                 {
 405                         // This is a hack that is likely required due to internal implementation difference in System.Uri. Our Uri has two readonly collection properties
 406                         if (this == XamlLanguage.Uri)
 407                                 yield break;
 408
 409                         var bf = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance;
 410
 411                         foreach (var pi in UnderlyingType.GetProperties (bf))
 412                                 if (pi.CanRead && (pi.CanWrite || IsCollectionType (pi.PropertyType) || typeof (IXmlSerializable).IsAssignableFrom (pi.PropertyType)) && pi.GetIndexParameters ().Length == 0)
 413                                         yield return new XamlMember (pi, SchemaContext);
 414                         foreach (var ei in UnderlyingType.GetEvents (bf))
 415                                 yield return new XamlMember (ei, SchemaContext);
 416                 }
 417
 418                 static bool IsPublicAccessor (MethodInfo mi)
 419                 {
 420                         return mi != null && mi.IsPublic;
 421                 }
 422
 423                 bool IsCollectionType (Type type)
 424                 {
 425                         if (type == null)
 426                                 return false;
 427                         var xt = SchemaContext.GetXamlType (type);
 428                         return xt.LookupCollectionKind () != XamlCollectionKind.None;
 429                 }
 430
 431                 protected virtual IList<XamlType> LookupAllowedContentTypes ()
 432                 {
 433                         // the actual implementation is very different from what is documented :(
 434                         return null;
 435
 436                         /*
 437                         var l = new List<XamlType> ();
 438                         if (ContentWrappers != null)
 439                                 l.AddRange (ContentWrappers);
 440                         if (ContentProperty != null)
 441                                 l.Add (ContentProperty.Type);
 442                         if (ItemType != null)
 443                                 l.Add (ItemType);
 444                         return l.Count > 0 ? l : null;
 445                         */
 446                 }
 447
 448                 protected virtual XamlMember LookupAttachableMember (string name)
 449                 {
 450                         throw new NotImplementedException ();
 451                 }
 452
 453                 [MonoTODO]
 454                 protected virtual XamlType LookupBaseType ()
 455                 {
 456                         if (base_type == null) {
 457                                 if (UnderlyingType == null)
 458                                         // FIXME: probably something advanced is needed here.
 459                                         base_type = new XamlType (typeof (object), SchemaContext, Invoker);
 460                                 else
 461                                         base_type = type.BaseType == null || type.BaseType == typeof (object) ? null : new XamlType (type.BaseType, SchemaContext, Invoker);
 462                         }
 463                         return base_type;
 464                 }
 465
 466                 // This implementation is not verified. (No place to use.)
 467                 protected virtual XamlCollectionKind LookupCollectionKind ()
 468                 {
 469                         if (UnderlyingType == null)
 470                                 return BaseType != null ? BaseType.LookupCollectionKind () : XamlCollectionKind.None;
 471                         if (type.IsArray)
 472                                 return XamlCollectionKind.Array;
 473
 474                         if (type.ImplementsAnyInterfacesOf (typeof (IDictionary), typeof (IDictionary<,>)))
 475                                 return XamlCollectionKind.Dictionary;
 476
 477                         if (type.ImplementsAnyInterfacesOf (typeof (IList), typeof (ICollection<>)))
 478                                 return XamlCollectionKind.Collection;
 479
 480                         return XamlCollectionKind.None;
 481                 }
 482
 483                 protected virtual bool LookupConstructionRequiresArguments ()
 484                 {
 485                         if (UnderlyingType == null)
 486                                 return false;
 487
 488                         // not sure if it is required, but MemberDefinition return true while they are abstract and it makes no sense.
 489                         if (UnderlyingType.IsAbstract)
 490                                 return true;
 491
 492                         // FIXME: probably some primitive types are treated as special.
 493                         switch (Type.GetTypeCode (UnderlyingType)) {
 494                         case TypeCode.String:
 495                                 return true;
 496                         case TypeCode.Object:
 497                                 if (UnderlyingType == typeof (TimeSpan))
 498                                         return false;
 499                                 break;
 500                         default:
 501                                 return false;
 502                         }
 503
 504                         return UnderlyingType.GetConstructor (BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance, null, Type.EmptyTypes, null) == null;
 505                 }
 506
 507                 protected virtual XamlMember LookupContentProperty ()
 508                 {
 509                         var a = this.GetCustomAttribute<ContentPropertyAttribute> ();
 510                         return a != null && a.Name != null ? GetMember (a.Name) : null;
 511                 }
 512
 513                 protected virtual IList<XamlType> LookupContentWrappers ()
 514                 {
 515                         if (GetCustomAttributeProvider () == null)
 516                                 return null;
 517
 518                         var arr = GetCustomAttributeProvider ().GetCustomAttributes (typeof (ContentWrapperAttribute), false);
 519                         if (arr == null || arr.Length == 0)
 520                                 return null;
 521                         var l = new XamlType [arr.Length];
 522                         for (int i = 0; i < l.Length; i++)
 523                                 l [i] = SchemaContext.GetXamlType (((ContentWrapperAttribute) arr [i]).ContentWrapper);
 524                         return l;
 525                 }
 526
 527                 internal ICustomAttributeProvider GetCustomAttributeProvider ()
 528                 {
 529                         return LookupCustomAttributeProvider ();
 530                 }
 531
 532                 protected internal virtual ICustomAttributeProvider LookupCustomAttributeProvider ()
 533                 {
 534                         return UnderlyingType;
 535                 }
 536
 537                 protected virtual XamlValueConverter<XamlDeferringLoader> LookupDeferringLoader ()
 538                 {
 539                         throw new NotImplementedException ();
 540                 }
 541
 542                 protected virtual XamlTypeInvoker LookupInvoker ()
 543                 {
 544                         return invoker;
 545                 }
 546
 547                 protected virtual bool LookupIsAmbient ()
 548                 {
 549                         return this.GetCustomAttribute<AmbientAttribute> () != null;
 550                 }
 551
 552                 // It is documented as if it were to reflect spec. section 5.2,
 553                 // but the actual behavior shows it is *totally* wrong.
 554                 // Here I have implemented this based on the nunit test results. sigh.
 555                 protected virtual bool LookupIsConstructible ()
 556                 {
 557                         if (UnderlyingType == null)
 558                                 return true;
 559                         if (IsMarkupExtension)
 560                                 return true;
 561                         if (UnderlyingType.IsAbstract)
 562                                 return false;
 563                         if (!IsNameValid)
 564                                 return false;
 565                         return true;
 566                 }
 567
 568                 protected virtual bool LookupIsMarkupExtension ()
 569                 {
 570                         return typeof (MarkupExtension).IsAssignableFrom (UnderlyingType);
 571                 }
 572
 573                 protected virtual bool LookupIsNameScope ()
 574                 {
 575                         return typeof (INameScope).IsAssignableFrom (UnderlyingType);
 576                 }
 577
 578                 protected virtual bool LookupIsNullable ()
 579                 {
 580                         return !type.IsValueType || type.ImplementsInterface (typeof (Nullable<>));
 581                 }
 582
 583                 protected virtual bool LookupIsPublic ()
 584                 {
 585                         return underlying_type == null || underlying_type.IsPublic || underlying_type.IsNestedPublic;
 586                 }
 587
 588                 protected virtual bool LookupIsUnknown ()
 589                 {
 590                         return UnderlyingType == null;
 591                 }
 592
 593                 protected virtual bool LookupIsWhitespaceSignificantCollection ()
 594                 {
 595                         // probably for unknown types, it should preserve whitespaces.
 596                         return IsUnknown || this.GetCustomAttribute<WhitespaceSignificantCollectionAttribute> () != null;
 597                 }
 598
 599                 protected virtual bool LookupIsXData ()
 600                 {
 601                         return CanAssignTo (SchemaContext.GetXamlType (typeof (IXmlSerializable)));
 602                 }
 603
 604                 protected virtual XamlType LookupItemType ()
 605                 {
 606                         if (IsArray)
 607                                 return new XamlType (type.GetElementType (), SchemaContext);
 608                         if (IsDictionary) {
 609                                 if (!IsGeneric)
 610                                         return new XamlType (typeof (object), SchemaContext);
 611                                 return new XamlType (type.GetGenericArguments () [1], SchemaContext);
 612                         }
 613                         if (!IsCollection)
 614                                 return null;
 615                         if (!IsGeneric)
 616                                 return new XamlType (typeof (object), SchemaContext);
 617                         return new XamlType (type.GetGenericArguments () [0], SchemaContext);
 618                 }
 619
 620                 protected virtual XamlType LookupKeyType ()
 621                 {
 622                         if (!IsDictionary)
 623                                 return null;
 624                         if (!IsGeneric)
 625                                 return new XamlType (typeof (object), SchemaContext);
 626                         return new XamlType (type.GetGenericArguments () [0], SchemaContext);
 627                 }
 628
 629                 protected virtual XamlType LookupMarkupExtensionReturnType ()
 630                 {
 631                         var a = this.GetCustomAttribute<MarkupExtensionReturnTypeAttribute> ();
 632                         return a != null ? new XamlType (a.ReturnType, SchemaContext) : null;
 633                 }
 634
 635                 protected virtual XamlMember LookupMember (string name, bool skipReadOnlyCheck)
 636                 {
 637                         // FIXME: verify if this does not filter out events.
 638                         return GetAllMembers ().FirstOrDefault (m => m.Name == name && (skipReadOnlyCheck || !m.IsReadOnly || m.Type.IsCollection || m.Type.IsDictionary || m.Type.IsArray));
 639                 }
 640
 641                 protected virtual IList<XamlType> LookupPositionalParameters (int parameterCount)
 642                 {
 643                         if (UnderlyingType == null/* || !IsMarkupExtension*/) // see nunit tests...
 644                                 return null;
 645
 646                         // check if there is applicable ConstructorArgumentAttribute.
 647                         // If there is, then return its type.
 648                         if (parameterCount == 1) {
 649                                 foreach (var xm in GetAllMembers ()) {
 650                                         var ca = xm.GetCustomAttributeProvider ().GetCustomAttribute<ConstructorArgumentAttribute> (false);
 651                                         if (ca != null)
 652                                                 return new XamlType [] {xm.Type};
 653                                 }
 654                         }
 655
 656                         var methods = (from m in UnderlyingType.GetConstructors (BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Instance) where m.GetParameters ().Length == parameterCount select m).ToArray ();
 657                         if (methods.Length == 1)
 658                                 return (from p in methods [0].GetParameters () select SchemaContext.GetXamlType (p.ParameterType)).ToArray ();
 659
 660                         if (SchemaContext.SupportMarkupExtensionsWithDuplicateArity)
 661                                 throw new NotSupportedException ("The default LookupPositionalParameters implementation does not allow duplicate arity of markup extensions");
 662                         return null;
 663                 }
 664
 665                 BindingFlags flags_get_static = BindingFlags.Public | BindingFlags.NonPublic | BindingFlags.Static;
 666
 667                 protected virtual EventHandler<XamlSetMarkupExtensionEventArgs> LookupSetMarkupExtensionHandler ()
 668                 {
 669                         var a = this.GetCustomAttribute<XamlSetMarkupExtensionAttribute> ();
 670                         if (a == null)
 671                                 return null;
 672                         var mi = type.GetMethod (a.XamlSetMarkupExtensionHandler, flags_get_static);
 673                         if (mi == null)
 674                                 throw new ArgumentException ("Binding to XamlSetMarkupExtensionHandler failed");
 675                         return (EventHandler<XamlSetMarkupExtensionEventArgs>) Delegate.CreateDelegate (typeof (EventHandler<XamlSetMarkupExtensionEventArgs>), mi);
 676                 }
 677
 678                 protected virtual EventHandler<XamlSetTypeConverterEventArgs> LookupSetTypeConverterHandler ()
 679                 {
 680                         var a = this.GetCustomAttribute<XamlSetTypeConverterAttribute> ();
 681                         if (a == null)
 682                                 return null;
 683                         var mi = type.GetMethod (a.XamlSetTypeConverterHandler, flags_get_static);
 684                         if (mi == null)
 685                                 throw new ArgumentException ("Binding to XamlSetTypeConverterHandler failed");
 686                         return (EventHandler<XamlSetTypeConverterEventArgs>) Delegate.CreateDelegate (typeof (EventHandler<XamlSetTypeConverterEventArgs>), mi);
 687                 }
 688
 689                 protected virtual bool LookupTrimSurroundingWhitespace ()
 690                 {
 691                         return this.GetCustomAttribute<TrimSurroundingWhitespaceAttribute> () != null;
 692                 }
 693
 694                 protected virtual XamlValueConverter<TypeConverter> LookupTypeConverter ()
 695                 {
 696                         var t = UnderlyingType;
 697                         if (t == null)
 698                                 return null;
 699
 700                         // equivalent to TypeExtension.
 701                         // FIXME: not sure if it should be specially handled here.
 702                         if (t == typeof (Type))
 703                                 t = typeof (TypeExtension);
 704
 705                         var a = GetCustomAttributeProvider ();
 706                         var ca = a != null ? a.GetCustomAttribute<TypeConverterAttribute> (false) : null;
 707                         if (ca != null)
 708                                 return SchemaContext.GetValueConverter<TypeConverter> (Type.GetType (ca.ConverterTypeName), this);
 709
 710                         if (t == typeof (object)) // This is a special case. ConverterType is null.
 711                                 return SchemaContext.GetValueConverter<TypeConverter> (null, this);
 712
 713                         // It's still not decent to check CollectionConverter.
 714                         var tct = TypeDescriptor.GetConverter (t).GetType ();
 715                         if (tct != typeof (TypeConverter) && tct != typeof (CollectionConverter) && tct != typeof (ReferenceConverter))
 716                                 return SchemaContext.GetValueConverter<TypeConverter> (tct, this);
 717                         return null;
 718                 }
 719
 720                 protected virtual Type LookupUnderlyingType ()
 721                 {
 722                         return underlying_type;
 723                 }
 724
 725                 protected virtual bool LookupUsableDuringInitialization ()
 726                 {
 727                         var a = this.GetCustomAttribute<UsableDuringInitializationAttribute> ();
 728                         return a != null && a.Usable;
 729                 }
 730
 731                 static XamlValueConverter<ValueSerializer> string_value_serializer;
 732
 733                 protected virtual XamlValueConverter<ValueSerializer> LookupValueSerializer ()
 734                 {
 735                         return LookupValueSerializer (this, GetCustomAttributeProvider ());
 736                 }
 737
 738                 internal static XamlValueConverter<ValueSerializer> LookupValueSerializer (XamlType targetType, ICustomAttributeProvider provider)
 739                 {
 740                         if (provider == null)
 741                                 return null;
 742
 743                         var a = provider.GetCustomAttribute<ValueSerializerAttribute> (true);
 744                         if (a != null)
 745                                 return new XamlValueConverter<ValueSerializer> (a.ValueSerializerType ?? Type.GetType (a.ValueSerializerTypeName), targetType);
 746
 747                         if (targetType.BaseType != null) {
 748                                 var ret = targetType.BaseType.LookupValueSerializer ();
 749                                 if (ret != null)
 750                                         return ret;
 751                         }
 752
 753                         if (targetType.UnderlyingType == typeof (string)) {
 754                                 if (string_value_serializer == null)
 755                                         string_value_serializer = new XamlValueConverter<ValueSerializer> (typeof (StringValueSerializer), targetType);
 756                                 return string_value_serializer;
 757                         }
 758
 759                         return null;
 760                 }
 761
 762                 static string GetXamlName (Type type)
 763                 {
 764                         string n;
 765                         if (!type.IsNested)
 766                                 n = type.Name;
 767                         else
 768                                 n = GetXamlName (type.DeclaringType) + "+" + type.Name;
 769                         if (type.IsGenericType && !type.ContainsGenericParameters) // the latter condition is to filter out "nested non-generic type within generic type".
 770                                 return n.Substring (0, n.IndexOf ('`'));
 771                         else
 772                                 return n;
 773                 }
 774         }
 775 }