mcs/gmcs/enum.cs

   1 //
   2 // enum.cs: Enum handling.
   3 //
   4 // Author: Miguel de Icaza (miguel@gnu.org)
   5 //         Ravi Pratap     (ravi@ximian.com)
   6 //
   7 // Licensed under the terms of the GNU GPL
   8 //
   9 // (C) 2001 Ximian, Inc (http://www.ximian.com)
  10 //
  11
  12 using System;
  13 using System.Collections;
  14 using System.Reflection;
  15 using System.Reflection.Emit;
  16
  17 namespace Mono.CSharp {
  18
  19         /// <summary>
  20         ///   Enumeration container
  21         /// </summary>
  22         public class Enum : DeclSpace {
  23                 ArrayList ordered_enums;
  24
  25                 public Expression BaseType;
  26
  27                 public Type UnderlyingType;
  28
  29                 Hashtable member_to_location;
  30                 Hashtable member_to_attributes;
  31
  32                 //
  33                 // This is for members that have been defined
  34                 //
  35                 Hashtable member_to_value;
  36
  37                 //
  38                 // This is used to mark members we're currently defining
  39                 //
  40                 Hashtable in_transit;
  41
  42                 ArrayList field_builders;
  43
  44                 public const int AllowedModifiers =
  45                         Modifiers.NEW |
  46                         Modifiers.PUBLIC |
  47                         Modifiers.PROTECTED |
  48                         Modifiers.INTERNAL |
  49                         Modifiers.PRIVATE;
  50
  51                 public Enum (NamespaceEntry ns, TypeContainer parent, Expression type,
  52                              int mod_flags, MemberName name, Attributes attrs, Location l)
  53                         : base (ns, parent, name, attrs, l)
  54                 {
  55                         this.BaseType = type;
  56                         ModFlags = Modifiers.Check (AllowedModifiers, mod_flags,
  57                                                     IsTopLevel ? Modifiers.INTERNAL : Modifiers.PRIVATE, l);
  58
  59                         ordered_enums = new ArrayList ();
  60                         member_to_location = new Hashtable ();
  61                         member_to_value = new Hashtable ();
  62                         in_transit = new Hashtable ();
  63                         field_builders = new ArrayList ();
  64                 }
  65
  66                 /// <summary>
  67                 ///   Adds @name to the enumeration space, with @expr
  68                 ///   being its definition.
  69                 /// </summary>
  70                 public AdditionResult AddEnumMember (string name, Expression expr, Location loc,
  71                                                      Attributes opt_attrs)
  72                 {
  73                         if (defined_names.Contains (name))
  74                                 return AdditionResult.NameExists;
  75
  76                         if (name == "value__") {
  77                                 Report.Error (76, loc, "An item in an enumeration can't have an identifier `value__'");
  78                                 return AdditionResult.Error;
  79                         }
  80
  81                         DefineName (name, expr);
  82
  83                         ordered_enums.Add (name);
  84                         member_to_location.Add (name, loc);
  85
  86                         if (member_to_attributes == null)
  87                                 member_to_attributes = new Hashtable ();
  88
  89                         member_to_attributes.Add (name, opt_attrs);
  90
  91                         return AdditionResult.Success;
  92                 }
  93
  94                 public override void ApplyAttributeBuilder (object builder, Attribute a, CustomAttributeBuilder cb)
  95                 {
  96                         ((TypeBuilder) builder).SetCustomAttribute (cb);
  97                 }
  98
  99                 //
 100                 // This is used by corlib compilation: we map from our
 101                 // type to a type that is consumable by the DefineField
 102                 //
 103                 Type MapToInternalType (Type t)
 104                 {
 105                         if (t == TypeManager.int32_type)
 106                                 return typeof (int);
 107                         if (t == TypeManager.int64_type)
 108                                 return typeof (long);
 109                         if (t == TypeManager.uint32_type)
 110                                 return typeof (uint);
 111                         if (t == TypeManager.uint64_type)
 112                                 return typeof (ulong);
 113                         if (t == TypeManager.float_type)
 114                                 return typeof (float);
 115                         if (t == TypeManager.double_type)
 116                                 return typeof (double);
 117                         if (t == TypeManager.byte_type)
 118                                 return typeof (byte);
 119                         if (t == TypeManager.sbyte_type)
 120                                 return typeof (sbyte);
 121                         if (t == TypeManager.char_type)
 122                                 return typeof (char);
 123                         if (t == TypeManager.short_type)
 124                                 return typeof (short);
 125                         if (t == TypeManager.ushort_type)
 126                                 return typeof (ushort);
 127
 128                         throw new Exception ();
 129                 }
 130
 131                 public override TypeBuilder DefineType ()
 132                 {
 133                         if (TypeBuilder != null)
 134                                 return TypeBuilder;
 135
 136                         TypeAttributes attr = Modifiers.TypeAttr (ModFlags, IsTopLevel);
 137
 138                         attr |= TypeAttributes.Class | TypeAttributes.Sealed;
 139
 140                         UnderlyingType = ResolveType (BaseType, false, Location);
 141
 142                         if (UnderlyingType != TypeManager.int32_type &&
 143                             UnderlyingType != TypeManager.uint32_type &&
 144                             UnderlyingType != TypeManager.int64_type &&
 145                             UnderlyingType != TypeManager.uint64_type &&
 146                             UnderlyingType != TypeManager.short_type &&
 147                             UnderlyingType != TypeManager.ushort_type &&
 148                             UnderlyingType != TypeManager.byte_type  &&
 149                             UnderlyingType != TypeManager.sbyte_type) {
 150                                 Report.Error (1008, Location,
 151                                               "Type byte, sbyte, short, ushort, int, uint, " +
 152                                               "long, or ulong expected (got: " +
 153                                               TypeManager.CSharpName (UnderlyingType) + ")");
 154                                 return null;
 155                         }
 156
 157                         if (IsTopLevel) {
 158                                 if (TypeManager.NamespaceClash (Name, Location))
 159                                         return null;
 160
 161                                 ModuleBuilder builder = CodeGen.Module.Builder;
 162
 163                                 TypeBuilder = builder.DefineType (Name, attr, TypeManager.enum_type);
 164                         } else {
 165                                 TypeBuilder builder = Parent.TypeBuilder;
 166
 167                                 TypeBuilder = builder.DefineNestedType (
 168                                         Basename, attr, TypeManager.enum_type);
 169                         }
 170
 171                         //
 172                         // Call MapToInternalType for corlib
 173                         //
 174                         TypeBuilder.DefineField ("value__", UnderlyingType,
 175                                                  FieldAttributes.Public | FieldAttributes.SpecialName
 176                                                  | FieldAttributes.RTSpecialName);
 177
 178                         TypeManager.AddEnumType (Name, TypeBuilder, this);
 179
 180                         return TypeBuilder;
 181                 }
 182
 183                 bool IsValidEnumConstant (Expression e)
 184                 {
 185                         if (!(e is Constant))
 186                                 return false;
 187
 188                         if (e is IntConstant || e is UIntConstant || e is LongConstant ||
 189                             e is ByteConstant || e is SByteConstant || e is ShortConstant ||
 190                             e is UShortConstant || e is ULongConstant || e is EnumConstant ||
 191                             e is CharConstant)
 192                                 return true;
 193                         else
 194                                 return false;
 195                 }
 196
 197                 object GetNextDefaultValue (object default_value)
 198                 {
 199                         if (UnderlyingType == TypeManager.int32_type) {
 200                                 int i = (int) default_value;
 201
 202                                 if (i < System.Int32.MaxValue)
 203                                         return ++i;
 204                                 else
 205                                         return null;
 206                         } else if (UnderlyingType == TypeManager.uint32_type) {
 207                                 uint i = (uint) default_value;
 208
 209                                 if (i < System.UInt32.MaxValue)
 210                                         return ++i;
 211                                 else
 212                                         return null;
 213                         } else if (UnderlyingType == TypeManager.int64_type) {
 214                                 long i = (long) default_value;
 215
 216                                 if (i < System.Int64.MaxValue)
 217                                         return ++i;
 218                                 else
 219                                         return null;
 220                         } else if (UnderlyingType == TypeManager.uint64_type) {
 221                                 ulong i = (ulong) default_value;
 222
 223                                 if (i < System.UInt64.MaxValue)
 224                                         return ++i;
 225                                 else
 226                                         return null;
 227                         } else if (UnderlyingType == TypeManager.short_type) {
 228                                 short i = (short) default_value;
 229
 230                                 if (i < System.Int16.MaxValue)
 231                                         return ++i;
 232                                 else
 233                                         return null;
 234                         } else if (UnderlyingType == TypeManager.ushort_type) {
 235                                 ushort i = (ushort) default_value;
 236
 237                                 if (i < System.UInt16.MaxValue)
 238                                         return ++i;
 239                                 else
 240                                         return null;
 241                         } else if (UnderlyingType == TypeManager.byte_type) {
 242                                 byte i = (byte) default_value;
 243
 244                                 if (i < System.Byte.MaxValue)
 245                                         return ++i;
 246                                 else
 247                                         return null;
 248                         } else if (UnderlyingType == TypeManager.sbyte_type) {
 249                                 sbyte i = (sbyte) default_value;
 250
 251                                 if (i < System.SByte.MaxValue)
 252                                         return ++i;
 253                                 else
 254                                         return null;
 255                         }
 256
 257                         return null;
 258                 }
 259
 260                 void Error_ConstantValueCannotBeConverted (object val, Location loc)
 261                 {
 262                         if (val is Constant)
 263                                 Report.Error (31, loc, "Constant value '" + ((Constant) val).AsString () +
 264                                               "' cannot be converted" +
 265                                               " to a " + TypeManager.CSharpName (UnderlyingType));
 266                         else
 267                                 Report.Error (31, loc, "Constant value '" + val +
 268                                               "' cannot be converted" +
 269                                               " to a " + TypeManager.CSharpName (UnderlyingType));
 270                         return;
 271                 }
 272
 273                 /// <summary>
 274                 ///  Determines if a standard implicit conversion exists from
 275                 ///  expr_type to target_type
 276                 /// </summary>
 277                 public static bool ImplicitConversionExists (Type expr_type, Type target_type)
 278                 {
 279                         expr_type = TypeManager.TypeToCoreType (expr_type);
 280
 281                         if (expr_type == TypeManager.void_type)
 282                                 return false;
 283
 284                         if (expr_type == target_type)
 285                                 return true;
 286
 287                         // First numeric conversions
 288
 289                         if (expr_type == TypeManager.sbyte_type){
 290                                 //
 291                                 // From sbyte to short, int, long, float, double.
 292                                 //
 293                                 if ((target_type == TypeManager.int32_type) ||
 294                                     (target_type == TypeManager.int64_type) ||
 295                                     (target_type == TypeManager.double_type) ||
 296                                     (target_type == TypeManager.float_type)  ||
 297                                     (target_type == TypeManager.short_type) ||
 298                                     (target_type == TypeManager.decimal_type))
 299                                         return true;
 300
 301                         } else if (expr_type == TypeManager.byte_type){
 302                                 //
 303                                 // From byte to short, ushort, int, uint, long, ulong, float, double
 304                                 //
 305                                 if ((target_type == TypeManager.short_type) ||
 306                                     (target_type == TypeManager.ushort_type) ||
 307                                     (target_type == TypeManager.int32_type) ||
 308                                     (target_type == TypeManager.uint32_type) ||
 309                                     (target_type == TypeManager.uint64_type) ||
 310                                     (target_type == TypeManager.int64_type) ||
 311                                     (target_type == TypeManager.float_type) ||
 312                                     (target_type == TypeManager.double_type) ||
 313                                     (target_type == TypeManager.decimal_type))
 314                                         return true;
 315
 316                         } else if (expr_type == TypeManager.short_type){
 317                                 //
 318                                 // From short to int, long, float, double
 319                                 //
 320                                 if ((target_type == TypeManager.int32_type) ||
 321                                     (target_type == TypeManager.int64_type) ||
 322                                     (target_type == TypeManager.double_type) ||
 323                                     (target_type == TypeManager.float_type) ||
 324                                     (target_type == TypeManager.decimal_type))
 325                                         return true;
 326
 327                         } else if (expr_type == TypeManager.ushort_type){
 328                                 //
 329                                 // From ushort to int, uint, long, ulong, float, double
 330                                 //
 331                                 if ((target_type == TypeManager.uint32_type) ||
 332                                     (target_type == TypeManager.uint64_type) ||
 333                                     (target_type == TypeManager.int32_type) ||
 334                                     (target_type == TypeManager.int64_type) ||
 335                                     (target_type == TypeManager.double_type) ||
 336                                     (target_type == TypeManager.float_type) ||
 337                                     (target_type == TypeManager.decimal_type))
 338                                         return true;
 339
 340                         } else if (expr_type == TypeManager.int32_type){
 341                                 //
 342                                 // From int to long, float, double
 343                                 //
 344                                 if ((target_type == TypeManager.int64_type) ||
 345                                     (target_type == TypeManager.double_type) ||
 346                                     (target_type == TypeManager.float_type) ||
 347                                     (target_type == TypeManager.decimal_type))
 348                                         return true;
 349
 350                         } else if (expr_type == TypeManager.uint32_type){
 351                                 //
 352                                 // From uint to long, ulong, float, double
 353                                 //
 354                                 if ((target_type == TypeManager.int64_type) ||
 355                                     (target_type == TypeManager.uint64_type) ||
 356                                     (target_type == TypeManager.double_type) ||
 357                                     (target_type == TypeManager.float_type) ||
 358                                     (target_type == TypeManager.decimal_type))
 359                                         return true;
 360
 361                         } else if ((expr_type == TypeManager.uint64_type) ||
 362                                    (expr_type == TypeManager.int64_type)) {
 363                                 //
 364                                 // From long/ulong to float, double
 365                                 //
 366                                 if ((target_type == TypeManager.double_type) ||
 367                                     (target_type == TypeManager.float_type) ||
 368                                     (target_type == TypeManager.decimal_type))
 369                                         return true;
 370
 371                         } else if (expr_type == TypeManager.char_type){
 372                                 //
 373                                 // From char to ushort, int, uint, long, ulong, float, double
 374                                 //
 375                                 if ((target_type == TypeManager.ushort_type) ||
 376                                     (target_type == TypeManager.int32_type) ||
 377                                     (target_type == TypeManager.uint32_type) ||
 378                                     (target_type == TypeManager.uint64_type) ||
 379                                     (target_type == TypeManager.int64_type) ||
 380                                     (target_type == TypeManager.float_type) ||
 381                                     (target_type == TypeManager.double_type) ||
 382                                     (target_type == TypeManager.decimal_type))
 383                                         return true;
 384
 385                         } else if (expr_type == TypeManager.float_type){
 386                                 //
 387                                 // float to double
 388                                 //
 389                                 if (target_type == TypeManager.double_type)
 390                                         return true;
 391                         }
 392
 393                         return false;
 394                 }
 395
 396                 //
 397                 // Horrible, horrible.  But there is no other way we can pass the EmitContext
 398                 // to the recursive definition triggered by the evaluation of a forward
 399                 // expression
 400                 //
 401                 static EmitContext current_ec = null;
 402
 403                 /// <summary>
 404                 ///  This is used to lookup the value of an enum member. If the member is undefined,
 405                 ///  it attempts to define it and return its value
 406                 /// </summary>
 407                 public object LookupEnumValue (EmitContext ec, string name, Location loc)
 408                 {
 409
 410                         object default_value = null;
 411                         Constant c = null;
 412
 413                         default_value = member_to_value [name];
 414
 415                         if (default_value != null)
 416                                 return default_value;
 417
 418                         //
 419                         // This may happen if we're calling a method in System.Enum, for instance
 420                         // Enum.IsDefined().
 421                         //
 422                         if (!defined_names.Contains (name))
 423                                 return null;
 424
 425                         if (in_transit.Contains (name)) {
 426                                 Report.Error (110, loc, "The evaluation of the constant value for `" +
 427                                               Name + "." + name + "' involves a circular definition.");
 428                                 return null;
 429                         }
 430
 431                         //
 432                         // So if the above doesn't happen, we have a member that is undefined
 433                         // We now proceed to define it
 434                         //
 435                         Expression val = this [name];
 436
 437                         if (val == null) {
 438
 439                                 int idx = ordered_enums.IndexOf (name);
 440
 441                                 if (idx == 0)
 442                                         default_value = 0;
 443                                 else {
 444                                         for (int i = 0; i < idx; ++i) {
 445                                                 string n = (string) ordered_enums [i];
 446                                                 Location m_loc = (Mono.CSharp.Location)
 447                                                         member_to_location [n];
 448                                                 in_transit.Add (name, true);
 449
 450                                                 EmitContext old_ec = current_ec;
 451                                                 current_ec = ec;
 452
 453                                                 default_value = LookupEnumValue (ec, n, m_loc);
 454
 455                                                 current_ec = old_ec;
 456
 457                                                 in_transit.Remove (name);
 458                                                 if (default_value == null)
 459                                                         return null;
 460                                         }
 461
 462                                         default_value = GetNextDefaultValue (default_value);
 463                                 }
 464
 465                         } else {
 466                                 bool old = ec.InEnumContext;
 467                                 ec.InEnumContext = true;
 468                                 in_transit.Add (name, true);
 469
 470                                 EmitContext old_ec = current_ec;
 471                                 current_ec = ec;
 472                                 val = val.Resolve (ec);
 473                                 current_ec = old_ec;
 474
 475                                 in_transit.Remove (name);
 476                                 ec.InEnumContext = old;
 477
 478                                 if (val == null)
 479                                         return null;
 480
 481                                 if (!IsValidEnumConstant (val)) {
 482                                         Report.Error (
 483                                                 1008, loc,
 484                                                 "Type byte, sbyte, short, ushort, int, uint, long, or " +
 485                                                 "ulong expected (have: " + val + ")");
 486                                         return null;
 487                                 }
 488
 489                                 c = (Constant) val;
 490                                 default_value = c.GetValue ();
 491
 492                                 if (default_value == null) {
 493                                         Error_ConstantValueCannotBeConverted (c, loc);
 494                                         return null;
 495                                 }
 496
 497                                 if (val is EnumConstant){
 498                                         Type etype = TypeManager.EnumToUnderlying (c.Type);
 499
 500                                         if (!ImplicitConversionExists (etype, UnderlyingType)){
 501                                                 Convert.Error_CannotImplicitConversion (
 502                                                         loc, c.Type, UnderlyingType);
 503                                                 return null;
 504                                         }
 505                                 }
 506                         }
 507
 508                         FieldAttributes attr = FieldAttributes.Public | FieldAttributes.Static
 509                                         | FieldAttributes.Literal;
 510
 511                         FieldBuilder fb = TypeBuilder.DefineField (name, TypeBuilder, attr);
 512
 513                         bool fail;
 514                         default_value = TypeManager.ChangeType (default_value, UnderlyingType, out fail);
 515                         if (fail){
 516                                 Error_ConstantValueCannotBeConverted (c, loc);
 517                                 return null;
 518                         }
 519
 520                         fb.SetConstant (default_value);
 521                         field_builders.Add (fb);
 522                         member_to_value [name] = default_value;
 523
 524                         if (!TypeManager.RegisterFieldValue (fb, default_value))
 525                                 return null;
 526
 527                         //
 528                         // Now apply attributes
 529                         //
 530                         Attribute.ApplyAttributes (ec, fb, fb, (Attributes) member_to_attributes [name]);
 531
 532                         return default_value;
 533                 }
 534
 535                 public override bool DefineMembers (TypeContainer parent)
 536                 {
 537                         return true;
 538                 }
 539
 540                 public override bool Define (TypeContainer parent)
 541                 {
 542                         //
 543                         // If there was an error during DefineEnum, return
 544                         //
 545                         if (TypeBuilder == null)
 546                                 return false;
 547
 548                         EmitContext ec = new EmitContext (this, this, Location, null,
 549                                                           UnderlyingType, ModFlags, false);
 550
 551
 552                         object default_value = 0;
 553
 554                         FieldAttributes attr = FieldAttributes.Public | FieldAttributes.Static
 555                                              | FieldAttributes.Literal;
 556
 557
 558                         foreach (string name in ordered_enums) {
 559                                 //
 560                                 // Have we already been defined, thanks to some cross-referencing ?
 561                                 //
 562                                 if (member_to_value.Contains (name))
 563                                         continue;
 564
 565                                 Location loc = (Mono.CSharp.Location) member_to_location [name];
 566
 567                                 if (this [name] != null) {
 568                                         default_value = LookupEnumValue (ec, name, loc);
 569
 570                                         if (default_value == null)
 571                                                 return true;
 572                                 } else {
 573                                         if (name == "value__"){
 574                                                 Report.Error (76, loc, "The name `value__' is reserved for enumerations");
 575                                                 return false;
 576                                         }
 577
 578                                         FieldBuilder fb = TypeBuilder.DefineField (
 579                                                 name, TypeBuilder, attr);
 580
 581                                         if (default_value == null) {
 582                                            Report.Error (543, loc, "Enumerator value for '" + name + "' is too large to " +
 583                                                               "fit in its type");
 584                                                 return false;
 585                                         }
 586
 587                                         bool fail;
 588                                         default_value = TypeManager.ChangeType (default_value, UnderlyingType, out fail);
 589                                         if (fail){
 590                                                 Error_ConstantValueCannotBeConverted (default_value, loc);
 591                                                 return false;
 592                                         }
 593
 594                                         fb.SetConstant (default_value);
 595                                         field_builders.Add (fb);
 596                                         member_to_value [name] = default_value;
 597
 598                                         if (!TypeManager.RegisterFieldValue (fb, default_value))
 599                                                 return false;
 600
 601                                         //
 602                                         // Apply attributes on the enum member
 603                                         //
 604                                         Attribute.ApplyAttributes (ec, fb, fb, (Attributes) member_to_attributes [name]);
 605                                 }
 606
 607                                 default_value = GetNextDefaultValue (default_value);
 608                         }
 609                         return true;
 610                 }
 611
 612                 public override void Emit (TypeContainer tc)
 613                 {
 614                         if (OptAttributes != null) {
 615                                 EmitContext ec = new EmitContext (tc, this, Location, null, null, ModFlags, false);
 616                         Attribute.ApplyAttributes (ec, TypeBuilder, this, OptAttributes);
 617                         }
 618
 619                         base.Emit (tc);
 620                 }
 621
 622                 protected override bool IsIdentifierClsCompliant (DeclSpace ds)
 623                 {
 624                         if (!base.IsIdentifierClsCompliant (ds))
 625                                 return false;
 626
 627                         for (int i = 1; i < ordered_enums.Count; ++i) {
 628                                 string checked_name = ordered_enums [i] as string;
 629                                 for (int ii = 0; ii < ordered_enums.Count; ++ii) {
 630                                         if (ii == i)
 631                                                 continue;
 632
 633                                         string enumerator_name = ordered_enums [ii] as string;
 634                                         if (String.Compare (checked_name, enumerator_name, true) == 0) {
 635                                                 Report.SymbolRelatedToPreviousError ((Location)member_to_location [enumerator_name], enumerator_name);
 636                                                 Report.Error_T (3005, (Location)member_to_location [checked_name], GetEnumeratorName (checked_name));
 637                                                 break;
 638                                         }
 639                                 }
 640                         }
 641                         return true;
 642                 }
 643
 644                 protected override bool VerifyClsCompliance (DeclSpace ds)
 645                 {
 646                         if (!base.VerifyClsCompliance (ds))
 647                                 return false;
 648
 649                         if (!AttributeTester.IsClsCompliant (UnderlyingType)) {
 650                                 Report.Error_T (3009, Location, GetSignatureForError (), TypeManager.CSharpName (UnderlyingType));
 651                         }
 652
 653                         return true;
 654                 }
 655
 656                 /// <summary>
 657                 /// Returns full enum name.
 658                 /// </summary>
 659                 string GetEnumeratorName (string valueName)
 660                 {
 661                         return String.Concat (Name, ".", valueName);
 662                 }
 663
 664                 //
 665                 // IMemberFinder
 666                 //
 667                 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
 668                                                         MemberFilter filter, object criteria)
 669                 {
 670                         ArrayList members = new ArrayList ();
 671
 672                         if ((mt & MemberTypes.Field) != 0) {
 673                                 if (criteria is string){
 674                                         if (member_to_value [criteria] == null && current_ec != null){
 675                                                 LookupEnumValue (current_ec, (string) criteria, Location.Null);
 676                                         }
 677                                 }
 678
 679                                 foreach (FieldBuilder fb in field_builders)
 680                                         if (filter (fb, criteria) == true)
 681                                                 members.Add (fb);
 682                         }
 683
 684                         return new MemberList (members);
 685                 }
 686
 687                 public override MemberCache MemberCache {
 688                         get {
 689                                 return null;
 690                         }
 691                 }
 692
 693                 public ArrayList ValueNames {
 694                         get {
 695                                 return ordered_enums;
 696                         }
 697                 }
 698
 699                 // indexer
 700                 public Expression this [string name] {
 701                         get {
 702                                 return (Expression) defined_names [name];
 703                         }
 704                 }
 705         }
 706 }