mcs/class/corlib/System.Reflection/Binder.cs

   1 // System.Reflection.Binder
   2 //
   3 // Authors:
   4 //      Sean MacIsaac (macisaac@ximian.com)
   5 //      Paolo Molaro (lupus@ximian.com)
   6 //      Gonzalo Paniagua Javier (gonzalo@ximian.com)
   7 //
   8 // (C) Ximian, Inc. 2001 - 2003
   9 // (c) Copyright 2004 Novell, Inc. (http://www.novell.com)
  10
  11 //
  12 // Copyright (C) 2004 Novell, Inc (http://www.novell.com)
  13 //
  14 // Permission is hereby granted, free of charge, to any person obtaining
  15 // a copy of this software and associated documentation files (the
  16 // "Software"), to deal in the Software without restriction, including
  17 // without limitation the rights to use, copy, modify, merge, publish,
  18 // distribute, sublicense, and/or sell copies of the Software, and to
  19 // permit persons to whom the Software is furnished to do so, subject to
  20 // the following conditions:
  21 //
  22 // The above copyright notice and this permission notice shall be
  23 // included in all copies or substantial portions of the Software.
  24 //
  25 // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  26 // EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  27 // MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
  28 // NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
  29 // LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
  30 // OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
  31 // WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
  32 //
  33
  34 using System.Globalization;
  35 using System.Runtime.InteropServices;
  36
  37 namespace System.Reflection
  38 {
  39 #if NET_2_0
  40         [ComVisible (true)]
  41 #endif
  42         [Serializable]
  43         [ClassInterface(ClassInterfaceType.AutoDual)]
  44         public abstract class Binder
  45         {
  46                 protected Binder () {}
  47
  48                 public abstract FieldInfo BindToField (BindingFlags bindingAttr, FieldInfo[] match, object value, CultureInfo culture);
  49                 public abstract MethodBase BindToMethod (BindingFlags bindingAttr, MethodBase[] match, ref object[] args, ParameterModifier[] modifiers, CultureInfo culture, string[] names, out object state);
  50                 public abstract object ChangeType (object value, Type type, CultureInfo culture);
  51                 public abstract void ReorderArgumentArray( ref object[] args, object state);
  52                 public abstract MethodBase SelectMethod (BindingFlags bindingAttr, MethodBase[] match, Type[] types, ParameterModifier[] modifiers);
  53                 public abstract PropertyInfo SelectProperty( BindingFlags bindingAttr, PropertyInfo[] match, Type returnType, Type[] indexes, ParameterModifier[] modifiers);
  54
  55                 static Binder default_binder = new Default ();
  56
  57                 internal static Binder DefaultBinder {
  58                         get {
  59                                 return default_binder;
  60                         }
  61                 }
  62
  63                 internal static bool ConvertArgs (Binder binder, object[] args, ParameterInfo[] pinfo, CultureInfo culture) {
  64                         if (args == null) {
  65                                 if ( pinfo.Length == 0)
  66                                         return true;
  67                                 else
  68                                         throw new TargetParameterCountException ();
  69                         }
  70                         if (pinfo.Length != args.Length)
  71                                 throw new TargetParameterCountException ();
  72                         for (int i = 0; i < args.Length; ++i) {
  73                                 object v = binder.ChangeType (args [i], pinfo[i].ParameterType, culture);
  74                                 if ((v == null) && (args [i] != null))
  75                                         return false;
  76                                 args [i] = v;
  77                         }
  78                         return true;
  79                 }
  80
  81                 internal static int GetDerivedLevel (Type type)
  82                 {
  83                         Type searchType = type;
  84                         int level = 1;
  85
  86                         while (searchType.BaseType != null)
  87                         {
  88                                 level++;
  89                                 searchType = searchType.BaseType;
  90                         }
  91
  92                         return level;
  93                 }
  94
  95                 internal static MethodBase FindMostDerivedMatch (MethodBase [] match)
  96                 {
  97                         int highLevel = 0;
  98                         int matchId = -1;
  99                         int count = match.Length;
 100
 101                         for (int current = 0; current < count; current++)
 102                         {
 103                                 MethodBase m = match [current];
 104                                 int level = GetDerivedLevel (m.DeclaringType);
 105                                 if (level == highLevel)
 106                                         throw new AmbiguousMatchException ();
 107                                 // If the argument types differ we
 108                                 // have an ambigous match, as well
 109                                 if (matchId >= 0) {
 110                                         ParameterInfo[] p1 = m.GetParameters ();
 111                                         ParameterInfo[] p2 = match [matchId].GetParameters ();
 112                                         bool equal = true;
 113
 114                                         if (p1.Length != p2.Length)
 115                                                 equal = false;
 116                                         else {
 117                                                 int i;
 118
 119                                                 for (i = 0; i < p1.Length; ++i) {
 120                                                         if (p1 [i].ParameterType != p2 [i].ParameterType) {
 121                                                                 equal = false;
 122                                                                 break;
 123                                                         }
 124                                                 }
 125                                         }
 126
 127                                         if (!equal)
 128                                                 throw new AmbiguousMatchException ();
 129                                 }
 130
 131                                 if (level > highLevel)
 132                                 {
 133                                         highLevel = level;
 134                                         matchId = current;
 135                                 }
 136                         }
 137
 138                         return match[matchId];
 139                 }
 140
 141                 internal sealed class Default : Binder {
 142                         public override FieldInfo BindToField (BindingFlags bindingAttr, FieldInfo[] match, object value, CultureInfo culture)
 143                         {
 144                                 if (match == null)
 145                                         throw new ArgumentNullException ("match");
 146                                 foreach (FieldInfo f in match) {
 147                                         if (check_type (value.GetType (), f.FieldType))
 148                                                 return f;
 149                                 }
 150                                 return null;
 151                         }
 152
 153                         //
 154                         // FIXME: There was a MonoTODO, but it does not explain what the problem is
 155                         //
 156                         public override MethodBase BindToMethod (BindingFlags bindingAttr, MethodBase[] match, ref object[] args, ParameterModifier[] modifiers, CultureInfo culture, string[] names, out object state)
 157                         {
 158                                 Type[] types;
 159                                 if (args == null)
 160                                         types = Type.EmptyTypes;
 161                                 else {
 162                                         types = new Type [args.Length];
 163                                         for (int i = 0; i < args.Length; ++i) {
 164                                                 if (args [i] != null)
 165                                                         types [i] = args [i].GetType ();
 166                                         }
 167                                 }
 168                                 MethodBase selected = SelectMethod (bindingAttr, match, types, modifiers);
 169                                 state = null;
 170                                 if (names != null)
 171                                         ReorderParameters (names, ref args, selected);
 172                                 return selected;
 173                         }
 174
 175                         void ReorderParameters (string [] names, ref object [] args, MethodBase selected)
 176                         {
 177                                 object [] newArgs = new object [args.Length];
 178                                 Array.Copy (args, newArgs, args.Length);
 179                                 ParameterInfo [] plist = selected.GetParameters ();
 180                                 for (int n = 0; n < names.Length; n++)
 181                                         for (int p = 0; p < plist.Length; p++) {
 182                                                 if (names [n] == plist [p].Name) {
 183                                                         newArgs [p] = args [n];
 184                                                         break;
 185                                                 }
 186                                         }
 187                                 Array.Copy (newArgs, args, args.Length);
 188                         }
 189
 190                         static bool IsArrayAssignable (Type object_type, Type target_type)
 191                         {
 192                                 if (object_type.IsArray && target_type.IsArray)
 193                                         return IsArrayAssignable (object_type.GetElementType (), target_type.GetElementType ());
 194
 195                                 if (target_type.IsAssignableFrom (object_type))
 196                                         return true;
 197
 198                                 return false;
 199                         }
 200
 201                         public override object ChangeType (object value, Type type, CultureInfo culture)
 202                         {
 203                                 if (value == null)
 204                                         return null;
 205                                 Type vtype = value.GetType ();
 206                                 if (type.IsByRef)
 207                                         type = type.GetElementType ();
 208                                 if (vtype == type || type.IsInstanceOfType (value))
 209                                         return value;
 210                                 if (vtype.IsArray && type.IsArray){
 211                                         if (IsArrayAssignable (vtype.GetElementType (), type.GetElementType ()))
 212                                                 return value;
 213                                 }
 214
 215                                 if (check_type (vtype, type)) {
 216                                         // These are not supported by Convert
 217                                         if (type.IsEnum)
 218                                                 return Enum.ToObject (type, value);
 219                                         if (vtype == typeof (Char)) {
 220                                                 if (type == typeof (double))
 221                                                         return (double)(char)value;
 222                                                 if (type == typeof (float))
 223                                                         return (float)(char)value;
 224                                         }
 225                                         return Convert.ChangeType (value, type);
 226                                 }
 227                                 return null;
 228                         }
 229
 230                         [MonoTODO ("This method does not do anything in Mono")]
 231                         public override void ReorderArgumentArray (ref object[] args, object state)
 232                         {
 233                                 //do nothing until we support named arguments
 234                                 //throw new NotImplementedException ();
 235                         }
 236
 237                         private static bool check_type (Type from, Type to) {
 238                                 if (from == to)
 239                                         return true;
 240
 241                                 if (from == null)
 242                                         return true;
 243
 244                                 if (to.IsByRef != from.IsByRef)
 245                                         return false;
 246
 247                                 if (to.IsInterface)
 248                                         return to.IsAssignableFrom (from);
 249
 250                                 if (to.IsEnum) {
 251                                         to = Enum.GetUnderlyingType (to);
 252                                         if (from == to)
 253                                                 return true;
 254                                 }
 255
 256                                 TypeCode fromt = Type.GetTypeCode (from);
 257                                 TypeCode tot = Type.GetTypeCode (to);
 258
 259                                 switch (fromt) {
 260                                 case TypeCode.Char:
 261                                         switch (tot) {
 262                                         case TypeCode.UInt16:
 263                                         case TypeCode.UInt32:
 264                                         case TypeCode.Int32:
 265                                         case TypeCode.UInt64:
 266                                         case TypeCode.Int64:
 267                                         case TypeCode.Single:
 268                                         case TypeCode.Double:
 269                                                 return true;
 270                                         }
 271                                         return to == typeof (object);
 272                                 case TypeCode.Byte:
 273                                         switch (tot) {
 274                                         case TypeCode.Char:
 275                                         case TypeCode.UInt16:
 276                                         case TypeCode.Int16:
 277                                         case TypeCode.UInt32:
 278                                         case TypeCode.Int32:
 279                                         case TypeCode.UInt64:
 280                                         case TypeCode.Int64:
 281                                         case TypeCode.Single:
 282                                         case TypeCode.Double:
 283                                                 return true;
 284                                         }
 285                                         return to == typeof (object) || (from.IsEnum && to == typeof (Enum));
 286                                 case TypeCode.SByte:
 287                                         switch (tot) {
 288                                         case TypeCode.Int16:
 289                                         case TypeCode.Int32:
 290                                         case TypeCode.Int64:
 291                                         case TypeCode.Single:
 292                                         case TypeCode.Double:
 293                                                 return true;
 294                                         }
 295                                         return to == typeof (object) || (from.IsEnum && to == typeof (Enum));
 296                                 case TypeCode.UInt16:
 297                                         switch (tot) {
 298                                         case TypeCode.UInt32:
 299                                         case TypeCode.Int32:
 300                                         case TypeCode.UInt64:
 301                                         case TypeCode.Int64:
 302                                         case TypeCode.Single:
 303                                         case TypeCode.Double:
 304                                                 return true;
 305                                         }
 306                                         return to == typeof (object) || (from.IsEnum && to == typeof (Enum));
 307                                 case TypeCode.Int16:
 308                                         switch (tot) {
 309                                         case TypeCode.Int32:
 310                                         case TypeCode.Int64:
 311                                         case TypeCode.Single:
 312                                         case TypeCode.Double:
 313                                                 return true;
 314                                         }
 315                                         return to == typeof (object) || (from.IsEnum && to == typeof (Enum));
 316                                 case TypeCode.UInt32:
 317                                         switch (tot) {
 318                                         case TypeCode.UInt64:
 319                                         case TypeCode.Int64:
 320                                         case TypeCode.Single:
 321                                         case TypeCode.Double:
 322                                                 return true;
 323                                         }
 324                                         return to == typeof (object) || (from.IsEnum && to == typeof (Enum));
 325                                 case TypeCode.Int32:
 326                                         switch (tot) {
 327                                         case TypeCode.Int64:
 328                                         case TypeCode.Single:
 329                                         case TypeCode.Double:
 330                                                 return true;
 331                                         }
 332                                         return to == typeof (object) || (from.IsEnum && to == typeof (Enum));
 333                                 case TypeCode.UInt64:
 334                                 case TypeCode.Int64:
 335                                         switch (tot) {
 336                                         case TypeCode.Single:
 337                                         case TypeCode.Double:
 338                                                 return true;
 339                                         }
 340                                         return to == typeof (object) || (from.IsEnum && to == typeof (Enum));
 341                                 case TypeCode.Single:
 342                                         return tot == TypeCode.Double || to == typeof (object);
 343                                 default:
 344                                         /* TODO: handle valuetype -> byref */
 345                                         if (to == typeof (object) && from.IsValueType)
 346                                                 return true;
 347
 348                                         return to.IsAssignableFrom (from);
 349                                 }
 350                         }
 351
 352                         private static bool check_arguments (Type[] types, ParameterInfo[] args) {
 353                                 for (int i = 0; i < types.Length; ++i) {
 354                                         if (!check_type (types [i], args [i].ParameterType))
 355                                                 return false;
 356                                 }
 357                                 return true;
 358                         }
 359
 360                         public override MethodBase SelectMethod (BindingFlags bindingAttr, MethodBase[] match, Type[] types, ParameterModifier[] modifiers)
 361                         {
 362                                 MethodBase m;
 363                                 int i, j;
 364
 365                                 if (match == null)
 366                                         throw new ArgumentNullException ("match");
 367
 368                                 /* first look for an exact match... */
 369                                 for (i = 0; i < match.Length; ++i) {
 370                                         m = match [i];
 371                                         ParameterInfo[] args = m.GetParameters ();
 372                                         if (args.Length != types.Length)
 373                                                 continue;
 374                                         for (j = 0; j < types.Length; ++j) {
 375                                                 if (types [j] != args [j].ParameterType)
 376                                                         break;
 377                                         }
 378                                         if (j == types.Length)
 379                                                 return m;
 380                                 }
 381
 382                                 /* Try methods with ParamArray attribute */
 383                                 bool isdefParamArray = false;
 384                                 Type elementType = null;
 385                                 for (i = 0; i < match.Length; ++i) {
 386                                         m = match [i];
 387                                         ParameterInfo[] args = m.GetParameters ();
 388                                         if (args.Length > types.Length)
 389                                                 continue;
 390                                         else if (args.Length == 0)
 391                                                 continue;
 392                                         isdefParamArray = Attribute.IsDefined (args [args.Length - 1], typeof (ParamArrayAttribute));
 393                                         if (!isdefParamArray)
 394                                                 continue;
 395                                         elementType = args [args.Length - 1].ParameterType.GetElementType ();
 396                                         for (j = 0; j < types.Length; ++j) {
 397                                                 if (j < (args.Length - 1) && types [j] != args [j].ParameterType)
 398                                                         break;
 399                                                 else if (j >= (args.Length - 1) && types [j] != elementType)
 400                                                         break;
 401                                         }
 402                                         if (j == types.Length)
 403                                                 return m;
 404                                 }
 405
 406                                 if ((int)(bindingAttr & BindingFlags.ExactBinding) != 0)
 407                                         return null;
 408
 409                                 MethodBase result = null;
 410                                 for (i = 0; i < match.Length; ++i) {
 411                                         m = match [i];
 412                                         ParameterInfo[] args = m.GetParameters ();
 413                                         if (args.Length != types.Length)
 414                                                 continue;
 415                                         if (!check_arguments (types, args))
 416                                                 continue;
 417
 418                                         if (result != null)
 419                                                 result = GetBetterMethod (result, m, types);
 420                                         else
 421                                                 result = m;
 422                                 }
 423
 424                                 return result;
 425                         }
 426
 427                         MethodBase GetBetterMethod (MethodBase m1, MethodBase m2, Type [] types)
 428                         {
 429 #if NET_2_0
 430                                 if (m1.IsGenericMethodDefinition &&
 431                                     !m2.IsGenericMethodDefinition)
 432                                         return m2;
 433                                 if (m2.IsGenericMethodDefinition &&
 434                                     !m1.IsGenericMethodDefinition)
 435                                         return m1;
 436 #endif
 437
 438                                 ParameterInfo [] pl1 = m1.GetParameters ();
 439                                 ParameterInfo [] pl2 = m2.GetParameters ();
 440                                 int prev = 0;
 441                                 for (int i = 0; i < pl1.Length; i++) {
 442                                         int cmp = CompareCloserType (pl1 [i].ParameterType, pl2 [i].ParameterType);
 443                                         if (cmp != 0 && prev != 0 && prev != cmp)
 444                                                 throw new AmbiguousMatchException ();
 445                                         if (cmp != 0)
 446                                                 prev = cmp;
 447                                 }
 448                                 if (prev != 0)
 449                                         return prev > 0 ? m2 : m1;
 450
 451                                 Type dt1 = m1.DeclaringType;
 452                                 Type dt2 = m2.DeclaringType;
 453                                 if (dt1 != dt2) {
 454                                         if (dt1.IsSubclassOf(dt2))
 455                                                 return m1;
 456                                         if (dt2.IsSubclassOf(dt1))
 457                                                 return m2;
 458                                 }
 459
 460                                 bool va1 = (m1.CallingConvention & CallingConventions.VarArgs) != 0;
 461                                 bool va2 = (m2.CallingConvention & CallingConventions.VarArgs) != 0;
 462                                 if (va1 && !va2)
 463                                         return m2;
 464                                 if (va2 && !va1)
 465                                         return m1;
 466
 467                                 throw new AmbiguousMatchException ();
 468                         }
 469
 470                         int CompareCloserType (Type t1, Type t2)
 471                         {
 472                                 if (t1 == t2)
 473                                         return 0;
 474 #if NET_2_0
 475                                 if (t1.IsGenericParameter && !t2.IsGenericParameter)
 476                                         return 1; // t2
 477                                 if (!t1.IsGenericParameter && t2.IsGenericParameter)
 478                                         return -1; // t1
 479 #endif
 480                                 if (t1.HasElementType && t2.HasElementType)
 481                                         return CompareCloserType (
 482                                                 t1.GetElementType (),
 483                                                 t2.GetElementType ());
 484
 485                                 if (t1.IsSubclassOf (t2))
 486                                         return -1; // t1
 487                                 if (t2.IsSubclassOf (t1))
 488                                         return 1; // t2
 489
 490                                 if (t1.IsInterface && Array.IndexOf (t2.GetInterfaces (), t1) >= 0)
 491                                         return 1; // t2
 492                                 if (t2.IsInterface && Array.IndexOf (t1.GetInterfaces (), t2) >= 0)
 493                                         return -1; // t1
 494
 495                                 // What kind of cases could reach here?
 496                                 return 0;
 497                         }
 498
 499                         public override PropertyInfo SelectProperty (BindingFlags bindingAttr, PropertyInfo[] match, Type returnType, Type[] indexes, ParameterModifier[] modifiers)
 500                         {
 501                                 if (match == null || match.Length == 0)
 502                                         throw new ArgumentException ("No properties provided", "match");
 503
 504                                 bool haveRet = (returnType != null);
 505                                 int idxlen = (indexes != null) ? indexes.Length : -1;
 506                                 PropertyInfo result = null;
 507                                 int i;
 508                                 int best_score = Int32.MaxValue - 1;
 509                                 int fail_score = Int32.MaxValue;
 510                                 int level = 0;
 511
 512                                 for (i = match.Length - 1; i >= 0; i--) {
 513                                         PropertyInfo p = match [i];
 514                                         ParameterInfo[] args = p.GetIndexParameters ();
 515                                         if (idxlen >= 0 && idxlen != args.Length)
 516                                                 continue;
 517
 518                                         if (haveRet && p.PropertyType != returnType)
 519                                                 continue;
 520
 521                                         int score = Int32.MaxValue - 1;
 522                                         if (idxlen > 0) {
 523                                                 score = check_arguments_with_score (indexes, args);
 524                                                 if (score == -1)
 525                                                         continue;
 526                                         }
 527
 528                                         int new_level = GetDerivedLevel (p.DeclaringType);
 529                                         if (result != null) {
 530                                                 if (best_score < score)
 531                                                         continue;
 532
 533                                                 if (best_score == score) {
 534                                                         if (level == new_level) {
 535                                                                 // Keep searching. May be there's something
 536                                                                 // better for us.
 537                                                                 fail_score = score;
 538                                                                 continue;
 539                                                         }
 540
 541                                                         if (level > new_level)
 542                                                                 continue;
 543                                                 }
 544                                         }
 545
 546                                         result = p;
 547                                         best_score = score;
 548                                         level = new_level;
 549                                 }
 550
 551                                 if (fail_score <= best_score)
 552                                         throw new AmbiguousMatchException ();
 553
 554                                 return result;
 555                         }
 556
 557                         static int check_arguments_with_score (Type [] types, ParameterInfo [] args)
 558                         {
 559                                 int worst = -1;
 560
 561                                 for (int i = 0; i < types.Length; ++i) {
 562                                         int res = check_type_with_score (types [i], args [i].ParameterType);
 563                                         if (res == -1)
 564                                                 return -1;
 565
 566                                         if (worst < res)
 567                                                 worst = res;
 568                                 }
 569
 570                                 return worst;
 571                         }
 572
 573                         // 0 -> same type or null and !valuetype
 574                         // 1 -> to == Enum
 575                         // 2 -> value type that don't lose data
 576                         // 3 -> to == IsAssignableFrom
 577                         // 4 -> to == object
 578                         static int check_type_with_score (Type from, Type to)
 579                         {
 580                                 if (from == null)
 581                                         return to.IsValueType ? -1 : 0;
 582
 583                                 if (from == to)
 584                                         return 0;
 585
 586                                 if (to == typeof (object))
 587                                         return 4;
 588
 589                                 TypeCode fromt = Type.GetTypeCode (from);
 590                                 TypeCode tot = Type.GetTypeCode (to);
 591
 592                                 switch (fromt) {
 593                                 case TypeCode.Char:
 594                                         switch (tot) {
 595                                         case TypeCode.UInt16:
 596                                                 return 0;
 597
 598                                         case TypeCode.UInt32:
 599                                         case TypeCode.Int32:
 600                                         case TypeCode.UInt64:
 601                                         case TypeCode.Int64:
 602                                         case TypeCode.Single:
 603                                         case TypeCode.Double:
 604                                                 return 2;
 605                                         }
 606                                         return -1;
 607                                 case TypeCode.Byte:
 608                                         switch (tot) {
 609                                         case TypeCode.Char:
 610                                         case TypeCode.UInt16:
 611                                         case TypeCode.Int16:
 612                                         case TypeCode.UInt32:
 613                                         case TypeCode.Int32:
 614                                         case TypeCode.UInt64:
 615                                         case TypeCode.Int64:
 616                                         case TypeCode.Single:
 617                                         case TypeCode.Double:
 618                                                 return 2;
 619                                         }
 620                                         return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
 621                                 case TypeCode.SByte:
 622                                         switch (tot) {
 623                                         case TypeCode.Int16:
 624                                         case TypeCode.Int32:
 625                                         case TypeCode.Int64:
 626                                         case TypeCode.Single:
 627                                         case TypeCode.Double:
 628                                                 return 2;
 629                                         }
 630                                         return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
 631                                 case TypeCode.UInt16:
 632                                         switch (tot) {
 633                                         case TypeCode.UInt32:
 634                                         case TypeCode.Int32:
 635                                         case TypeCode.UInt64:
 636                                         case TypeCode.Int64:
 637                                         case TypeCode.Single:
 638                                         case TypeCode.Double:
 639                                                 return 2;
 640                                         }
 641                                         return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
 642                                 case TypeCode.Int16:
 643                                         switch (tot) {
 644                                         case TypeCode.Int32:
 645                                         case TypeCode.Int64:
 646                                         case TypeCode.Single:
 647                                         case TypeCode.Double:
 648                                                 return 2;
 649                                         }
 650                                         return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
 651                                 case TypeCode.UInt32:
 652                                         switch (tot) {
 653                                         case TypeCode.UInt64:
 654                                         case TypeCode.Int64:
 655                                         case TypeCode.Single:
 656                                         case TypeCode.Double:
 657                                                 return 2;
 658                                         }
 659                                         return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
 660                                 case TypeCode.Int32:
 661                                         switch (tot) {
 662                                         case TypeCode.Int64:
 663                                         case TypeCode.Single:
 664                                         case TypeCode.Double:
 665                                                 return 2;
 666                                         }
 667                                         return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
 668                                 case TypeCode.UInt64:
 669                                 case TypeCode.Int64:
 670                                         switch (tot) {
 671                                         case TypeCode.Single:
 672                                         case TypeCode.Double:
 673                                                 return 2;
 674                                         }
 675                                         return (from.IsEnum && to == typeof (Enum)) ? 1 : -1;
 676                                 case TypeCode.Single:
 677                                         return tot == TypeCode.Double ? 2 : -1;
 678                                 default:
 679                                         return (to.IsAssignableFrom (from)) ? 3 : -1;
 680                                 }
 681                         }
 682                 }
 683         }
 684 }
 685