mcs/gmcs/iterators.cs

   1 //
   2 // iterators.cs: Support for implementing iterators
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //
   7 // (C) 2003 Ximian, Inc.
   8 //
   9 // TODO:
  10 //    Flow analysis for Yield.
  11 //    Emit calls to base object constructor.
  12 //
  13 // Generics note:
  14 //    Current should be defined to return T, and IEnumerator.Current returns object
  15 //
  16
  17 using System;
  18 using System.Collections;
  19 using System.Reflection;
  20 using System.Reflection.Emit;
  21
  22 namespace Mono.CSharp {
  23
  24         public interface IIteratorContainer {
  25
  26                 //
  27                 // Invoked if a yield statement is found in the body
  28                 //
  29                 void SetYields ();
  30         }
  31
  32         public class Yield : Statement {
  33                 Expression expr;
  34                 ArrayList finally_blocks;
  35
  36                 public Yield (Expression expr, Location l)
  37                 {
  38                         this.expr = expr;
  39                         loc = l;
  40                 }
  41
  42                 public static bool CheckContext (EmitContext ec, Location loc)
  43                 {
  44                         if (ec.InFinally) {
  45                                 Report.Error (1625, loc, "Cannot yield in the body of a " +
  46                                               "finally clause");
  47                                 return false;
  48                         }
  49
  50                         if (ec.InUnsafe) {
  51                                 Report.Error (1629, loc, "Unsafe code may not appear in iterators");
  52                                 return false;
  53                         }
  54                         if (ec.InCatch){
  55                                 Report.Error (1631, loc, "Cannot yield a value in the body of a catch clause");
  56                                 return false;
  57                         }
  58
  59                         AnonymousContainer am = ec.CurrentAnonymousMethod;
  60                         if ((am != null) && !am.IsIterator){
  61                                 Report.Error (1621, loc, "The yield statement cannot be used inside anonymous method blocks");
  62                                 return false;
  63                         }
  64
  65                         if (ec.CurrentBranching.InTryWithCatch ()) {
  66                                 Report.Error (1626, loc, "Cannot yield a value in the body of a " +
  67                                         "try block with a catch clause");
  68                                 return false;
  69                         }
  70                         return true;
  71                 }
  72
  73                 public override bool Resolve (EmitContext ec)
  74                 {
  75                         expr = expr.Resolve (ec);
  76                         if (expr == null)
  77                                 return false;
  78
  79                         if (!CheckContext (ec, loc))
  80                                 return false;
  81
  82                         Iterator iterator = ec.CurrentIterator;
  83
  84                         if (expr.Type != iterator.IteratorType){
  85                                 expr = Convert.ImplicitConversionRequired (
  86                                         ec, expr, iterator.IteratorType, loc);
  87                                 if (expr == null)
  88                                         return false;
  89                         }
  90
  91                         ec.CurrentBranching.StealFinallyClauses (ref finally_blocks);
  92                         return true;
  93                 }
  94
  95                 protected override void DoEmit (EmitContext ec)
  96                 {
  97                         ec.CurrentIterator.MarkYield (ec, expr, finally_blocks);
  98                 }
  99         }
 100
 101         public class YieldBreak : Statement {
 102
 103                 public YieldBreak (Location l)
 104                 {
 105                         loc = l;
 106                 }
 107
 108                 public override bool Resolve (EmitContext ec)
 109                 {
 110                         if (!Yield.CheckContext (ec, loc))
 111                                 return false;
 112
 113                         ec.CurrentBranching.CurrentUsageVector.Goto ();
 114                         return true;
 115                 }
 116
 117                 protected override void DoEmit (EmitContext ec)
 118                 {
 119                         ec.CurrentIterator.EmitYieldBreak (ec.ig);
 120                 }
 121         }
 122
 123         public class Iterator : Class {
 124                 protected ToplevelBlock original_block;
 125                 protected ToplevelBlock block;
 126
 127                 Type original_iterator_type;
 128                 TypeExpr iterator_type_expr;
 129                 bool is_enumerable;
 130                 public readonly bool IsStatic;
 131
 132                 //
 133                 // The state as we generate the iterator
 134                 //
 135                 Label move_next_ok, move_next_error;
 136                 ArrayList resume_points = new ArrayList ();
 137                 int pc;
 138
 139                 //
 140                 // Context from the original method
 141                 //
 142                 GenericMethod generic_method;
 143                 TypeContainer container;
 144                 TypeExpr current_type;
 145                 Type this_type;
 146                 InternalParameters parameters;
 147                 InternalParameters original_parameters;
 148                 IMethodData orig_method;
 149
 150                 MethodInfo dispose_method;
 151                 MoveNextMethod move_next_method;
 152                 Constructor ctor;
 153                 CaptureContext cc;
 154
 155                 Expression enumerator_type;
 156                 Expression enumerable_type;
 157                 Expression generic_enumerator_type;
 158                 Expression generic_enumerable_type;
 159                 TypeArguments generic_args;
 160
 161                 protected enum State {
 162                         Uninitialized   = -2,
 163                         After,
 164                         Running
 165                 }
 166
 167                 static int proxy_count;
 168
 169                 public void EmitYieldBreak (ILGenerator ig)
 170                 {
 171                         ig.Emit (OpCodes.Ldarg_0);
 172                         IntConstant.EmitInt (ig, (int) State.After);
 173                         ig.Emit (OpCodes.Stfld, pc_field.FieldBuilder);
 174                         ig.Emit (OpCodes.Br, move_next_error);
 175                 }
 176
 177                 public void EmitMoveNext (EmitContext ec)
 178                 {
 179                         ILGenerator ig = ec.ig;
 180
 181                         move_next_ok = ig.DefineLabel ();
 182                         move_next_error = ig.DefineLabel ();
 183
 184                         LocalBuilder retval = ec.GetTemporaryLocal (TypeManager.int32_type);
 185
 186                         ig.BeginExceptionBlock ();
 187
 188                         Label dispatcher = ig.DefineLabel ();
 189                         ig.Emit (OpCodes.Br, dispatcher);
 190
 191                         ResumePoint entry_point = new ResumePoint (null);
 192                         resume_points.Add (entry_point);
 193                         entry_point.Define (ig);
 194
 195                         ec.EmitTopBlock (orig_method, original_block, parameters);
 196
 197                         EmitYieldBreak (ig);
 198
 199                         ig.MarkLabel (dispatcher);
 200
 201                         Label [] labels = new Label [resume_points.Count];
 202                         for (int i = 0; i < labels.Length; i++)
 203                                 labels [i] = ((ResumePoint) resume_points [i]).Label;
 204
 205                         ig.Emit (OpCodes.Ldarg_0);
 206                         ig.Emit (OpCodes.Ldfld, pc_field.FieldBuilder);
 207                         ig.Emit (OpCodes.Switch, labels);
 208
 209                         Label end = ig.DefineLabel ();
 210
 211                         ig.MarkLabel (move_next_error);
 212                         ig.Emit (OpCodes.Ldc_I4_0);
 213                         ig.Emit (OpCodes.Stloc, retval);
 214                         ig.Emit (OpCodes.Leave, end);
 215
 216                         ig.MarkLabel (move_next_ok);
 217                         ig.Emit (OpCodes.Ldc_I4_1);
 218                         ig.Emit (OpCodes.Stloc, retval);
 219                         ig.Emit (OpCodes.Leave, end);
 220
 221                         ig.BeginFaultBlock ();
 222
 223                         ig.Emit (OpCodes.Ldarg_0);
 224                         ig.Emit (OpCodes.Callvirt, dispose_method);
 225
 226                         ig.EndExceptionBlock ();
 227
 228                         ig.MarkLabel (end);
 229                         ig.Emit (OpCodes.Ldloc, retval);
 230                         ig.Emit (OpCodes.Ret);
 231                 }
 232
 233                 public void EmitDispose (EmitContext ec)
 234                 {
 235                         ILGenerator ig = ec.ig;
 236
 237                         Label end = ig.DefineLabel ();
 238                         Label dispatcher = ig.DefineLabel ();
 239                         ig.Emit (OpCodes.Br, dispatcher);
 240
 241                         Label [] labels = new Label [resume_points.Count];
 242                         for (int i = 0; i < labels.Length; i++) {
 243                                 ResumePoint point = (ResumePoint) resume_points [i];
 244
 245                                 if (point.FinallyBlocks == null) {
 246                                         labels [i] = end;
 247                                         continue;
 248                                 }
 249
 250                                 labels [i] = ig.DefineLabel ();
 251                                 ig.MarkLabel (labels [i]);
 252
 253                                 ig.BeginExceptionBlock ();
 254                                 ig.BeginFinallyBlock ();
 255
 256                                 foreach (ExceptionStatement stmt in point.FinallyBlocks) {
 257                                         if (stmt != null)
 258                                                 stmt.EmitFinally (ec);
 259                                 }
 260
 261                                 ig.EndExceptionBlock ();
 262                                 ig.Emit (OpCodes.Br, end);
 263                         }
 264
 265                         ig.MarkLabel (dispatcher);
 266                         ig.Emit (OpCodes.Ldarg_0);
 267                         ig.Emit (OpCodes.Ldfld, pc_field.FieldBuilder);
 268                         ig.Emit (OpCodes.Switch, labels);
 269
 270                         ig.Emit (OpCodes.Ldarg_0);
 271                         IntConstant.EmitInt (ig, (int) State.After);
 272                         ig.Emit (OpCodes.Stfld, pc_field.FieldBuilder);
 273
 274                         ig.MarkLabel (end);
 275                 }
 276
 277                 protected class ResumePoint
 278                 {
 279                         public Label Label;
 280                         public readonly ExceptionStatement[] FinallyBlocks;
 281
 282                         public ResumePoint (ArrayList list)
 283                         {
 284                                 if (list != null) {
 285                                         FinallyBlocks = new ExceptionStatement [list.Count];
 286                                         list.CopyTo (FinallyBlocks, 0);
 287                                 }
 288                         }
 289
 290                         public void Define (ILGenerator ig)
 291                         {
 292                                 Label = ig.DefineLabel ();
 293                                 ig.MarkLabel (Label);
 294                         }
 295                 }
 296
 297                 //
 298                 // Called back from Yield
 299                 //
 300                 public void MarkYield (EmitContext ec, Expression expr,
 301                                        ArrayList finally_blocks)
 302                 {
 303                         ILGenerator ig = ec.ig;
 304
 305                         // Store the new current
 306                         ig.Emit (OpCodes.Ldarg_0);
 307                         expr.Emit (ec);
 308                         ig.Emit (OpCodes.Stfld, current_field.FieldBuilder);
 309
 310                         // increment pc
 311                         pc++;
 312                         ig.Emit (OpCodes.Ldarg_0);
 313                         IntConstant.EmitInt (ig, pc);
 314                         ig.Emit (OpCodes.Stfld, pc_field.FieldBuilder);
 315
 316                         // Return ok
 317                         ig.Emit (OpCodes.Br, move_next_ok);
 318
 319                         ResumePoint point = new ResumePoint (finally_blocks);
 320                         resume_points.Add (point);
 321                         point.Define (ig);
 322                 }
 323
 324                 public void MarkFinally (EmitContext ec, ArrayList finally_blocks)
 325                 {
 326                         ILGenerator ig = ec.ig;
 327
 328                         // increment pc
 329                         pc++;
 330                         ig.Emit (OpCodes.Ldarg_0);
 331                         IntConstant.EmitInt (ig, pc);
 332                         ig.Emit (OpCodes.Stfld, pc_field.FieldBuilder);
 333
 334                         ResumePoint point = new ResumePoint (finally_blocks);
 335                         resume_points.Add (point);
 336                         point.Define (ig);
 337                 }
 338
 339                 private static MemberName MakeProxyName (string name, GenericMethod generic, Location loc)
 340                 {
 341                         int pos = name.LastIndexOf ('.');
 342                         if (pos > 0)
 343                                 name = name.Substring (pos + 1);
 344
 345                         string proxy_name = "<" + name + ">__" + (proxy_count++);
 346
 347                         if (generic != null) {
 348                                 TypeArguments args = new TypeArguments (loc);
 349                                 foreach (TypeParameter tparam in generic.CurrentTypeParameters)
 350                                         args.Add (new SimpleName (tparam.Name, loc));
 351                                 return new MemberName (proxy_name, args, loc);
 352                         } else
 353                                 return new MemberName (proxy_name, loc);
 354                 }
 355
 356                 //
 357                 // Our constructor
 358                 //
 359                 public Iterator (IMethodData m_container, TypeContainer container, GenericMethod generic,
 360                                  InternalParameters parameters, int modifiers)
 361                         : base (container.NamespaceEntry, container,
 362                                 MakeProxyName (m_container.MethodName.Name, generic, m_container.Location),
 363                                 (modifiers & Modifiers.UNSAFE) | Modifiers.PRIVATE, null)
 364                 {
 365                         this.orig_method = m_container;
 366
 367                         this.generic_method = generic;
 368                         this.container = container;
 369                         this.original_parameters = parameters;
 370                         this.original_block = orig_method.Block;
 371                         this.block = new ToplevelBlock (orig_method.Block, parameters.Parameters, orig_method.Location);
 372
 373                         if (generic != null) {
 374                                 ArrayList constraints = new ArrayList ();
 375                                 foreach (TypeParameter tparam in generic.TypeParameters)
 376                                         constraints.Add (tparam.Constraints);
 377
 378                                 SetParameterInfo (constraints);
 379                         }
 380
 381                         IsStatic = (modifiers & Modifiers.STATIC) != 0;
 382                 }
 383
 384                 public AnonymousContainer Host {
 385                         get { return move_next_method; }
 386                 }
 387
 388                 public bool DefineIterator ()
 389                 {
 390                         ec = new EmitContext (this, Location, null, null, ModFlags);
 391                         ec.CurrentAnonymousMethod = move_next_method;
 392                         ec.InIterator = true;
 393
 394                         if (!CheckType ()) {
 395                                 Report.Error (1624, Location,
 396                                         "The body of `{0}' cannot be an iterator block because `{1}' is not an iterator interface type",
 397                                         orig_method.GetSignatureForError (), TypeManager.CSharpName (orig_method.ReturnType));
 398                                 return false;
 399                         }
 400
 401                         for (int i = 0; i < original_parameters.Count; i++){
 402                                 Parameter.Modifier mod = original_parameters.ParameterModifier (i);
 403                                 if ((mod & (Parameter.Modifier.REF | Parameter.Modifier.OUT)) != 0){
 404                                         Report.Error (
 405                                                 1623, Location,
 406                                                 "Iterators cannot have ref or out parameters");
 407                                         return false;
 408                                 }
 409
 410                                 if ((mod & Parameter.Modifier.ARGLIST) != 0) {
 411                                         Report.Error (1636, Location, "__arglist is not allowed in parameter list of iterators");
 412                                         return false;
 413                                 }
 414
 415                                 if (original_parameters.ParameterType (i).IsPointer) {
 416                                         Report.Error (1637, Location, "Iterators cannot have unsafe parameters or yield types");
 417                                         return false;
 418                                 }
 419                         }
 420
 421                         if (container.CurrentType != null)
 422                                 this_type = container.CurrentType;
 423                         else
 424                                 this_type = container.TypeBuilder;
 425
 426                         container.AddIterator (this);
 427
 428                         orig_method.Block = block;
 429                         return true;
 430                 }
 431
 432                 MethodInfo FetchMethodDispose ()
 433                 {
 434                         MemberList dispose_list;
 435
 436                         dispose_list = FindMembers (
 437                                 current_type.Type,
 438                                 MemberTypes.Method, BindingFlags.Public | BindingFlags.Instance,
 439                                 Type.FilterName, "Dispose");
 440
 441                         if (dispose_list.Count != 1)
 442                                 throw new InternalErrorException ("Cannot find Dipose() method.");
 443
 444                         return (MethodInfo) dispose_list [0];
 445                 }
 446
 447                 protected override bool DoDefineMembers ()
 448                 {
 449                         ec.InIterator = true;
 450                         ec.CurrentAnonymousMethod = move_next_method;
 451                         ec.capture_context = cc;
 452
 453                         if (!base.DoDefineMembers ())
 454                                 return false;
 455
 456                         dispose_method = FetchMethodDispose ();
 457                         if (dispose_method == null)
 458                                 return false;
 459
 460                         return true;
 461                 }
 462
 463                 public override bool Define ()
 464                 {
 465                         if (!base.Define ())
 466                                 return false;
 467
 468                         ec.InIterator = true;
 469                         ec.CurrentAnonymousMethod = move_next_method;
 470                         ec.capture_context = cc;
 471
 472                         ec.TypeContainer = ec.TypeContainer.Parent;
 473
 474                         if (ec.TypeContainer.CurrentType != null)
 475                                 ec.ContainerType = ec.TypeContainer.CurrentType;
 476                         else
 477                                 ec.ContainerType = ec.TypeContainer.TypeBuilder;
 478
 479                         ec.ig = move_next_method.method.MethodBuilder.GetILGenerator ();
 480
 481                         if (!ctor.Define ())
 482                                 return false;
 483
 484                         bool unreachable;
 485
 486                         if (!ec.ResolveTopBlock (null, original_block, parameters, orig_method, out unreachable))
 487                                 return false;
 488
 489                         if (!ec.ResolveTopBlock (null, block, parameters, orig_method, out unreachable))
 490                                 return false;
 491
 492                         original_block.CompleteContexts ();
 493
 494                         cc.EmitAnonymousHelperClasses (ec);
 495
 496                         return true;
 497                 }
 498
 499                 TypeExpr InflateType (Type it)
 500                 {
 501                         if (generic_method == null)
 502                                 return new TypeExpression (it, Location);
 503
 504                         if (it.IsGenericParameter && (it.DeclaringMethod != null)) {
 505                                 int pos = it.GenericParameterPosition;
 506                                 it = CurrentTypeParameters [pos].Type;
 507                         } else if (it.IsGenericInstance) {
 508                                 Type[] args = it.GetGenericArguments ();
 509
 510                                 TypeArguments inflated = new TypeArguments (Location);
 511                                 foreach (Type t in args)
 512                                         inflated.Add (InflateType (t));
 513
 514                                 return new ConstructedType (it, inflated, Location);
 515                         } else if (it.IsArray) {
 516                                 TypeExpr et_expr = InflateType (it.GetElementType ());
 517                                 int rank = it.GetArrayRank ();
 518
 519                                 Type et = et_expr.ResolveAsTypeTerminal (ec).Type;
 520                                 it = et.MakeArrayType (rank);
 521                         }
 522
 523                         return new TypeExpression (it, Location);
 524                 }
 525
 526                 Parameter InflateParameter (Parameter param)
 527                 {
 528                         TypeExpr te = InflateType (param.ParameterType);
 529                         return new Parameter (
 530                                 te, param.Name, param.ModFlags, param.OptAttributes, param.Location);
 531                 }
 532
 533                 InternalParameters InflateParameters (Parameters parameters, EmitContext ec)
 534                 {
 535                         Parameter[] fixed_params = null;
 536                         if (parameters.FixedParameters != null) {
 537                                 fixed_params = new Parameter [parameters.FixedParameters.Length];
 538                                 for (int i = 0; i < fixed_params.Length; i++)
 539                                         fixed_params [i] = InflateParameter (parameters.FixedParameters [i]);
 540                         }
 541
 542                         Parameters new_params;
 543                         if (parameters.ArrayParameter != null) {
 544                                 Parameter array_param = InflateParameter (parameters.ArrayParameter);
 545                                 new_params = new Parameters (fixed_params, array_param);
 546                         } else
 547                                 new_params = new Parameters (fixed_params, parameters.HasArglist);
 548
 549                         Type [] types = new_params.GetParameterInfo (ec);
 550                         return new InternalParameters (types, new_params);
 551                 }
 552
 553                 protected override TypeExpr [] GetClassBases (out TypeExpr base_class)
 554                 {
 555                         iterator_type_expr = InflateType (original_iterator_type);
 556
 557                         generic_args = new TypeArguments (Location);
 558                         generic_args.Add (iterator_type_expr);
 559
 560                         ArrayList list = new ArrayList ();
 561                         if (is_enumerable) {
 562                                 enumerable_type = new TypeExpression (
 563                                         TypeManager.ienumerable_type, Location);
 564                                 list.Add (enumerable_type);
 565
 566                                 generic_enumerable_type = new ConstructedType (
 567                                         TypeManager.generic_ienumerable_type,
 568                                         generic_args, Location);
 569                                 list.Add (generic_enumerable_type);
 570                         }
 571
 572                         enumerator_type = new TypeExpression (
 573                                 TypeManager.ienumerator_type, Location);
 574                         list.Add (enumerator_type);
 575
 576                         list.Add (new TypeExpression (TypeManager.idisposable_type, Location));
 577
 578                         generic_enumerator_type = new ConstructedType (
 579                                 TypeManager.generic_ienumerator_type,
 580                                 generic_args, Location);
 581                         list.Add (generic_enumerator_type);
 582
 583                         Bases = list;
 584
 585                         return base.GetClassBases (out base_class);
 586                 }
 587
 588                 //
 589                 // Returns the new block for the method, or null on failure
 590                 //
 591                 protected override bool DefineNestedTypes ()
 592                 {
 593                         if (CurrentType != null)
 594                                 current_type = new TypeExpression (CurrentType, Location);
 595                         else
 596                                 current_type = new TypeExpression (TypeBuilder, Location);
 597
 598                         parameters = InflateParameters (original_parameters.Parameters, ec);
 599
 600                         Define_Fields ();
 601                         Define_Current (false);
 602                         Define_Current (true);
 603                         Define_MoveNext ();
 604                         Define_Reset ();
 605                         Define_Dispose ();
 606
 607                         Define_Constructor ();
 608
 609                         Create_Block ();
 610
 611                         if (is_enumerable) {
 612                                 Define_GetEnumerator (false);
 613                                 Define_GetEnumerator (true);
 614                         }
 615
 616                         return base.DefineNestedTypes ();
 617                 }
 618
 619                 Field pc_field;
 620                 Field current_field;
 621                 Method dispose;
 622
 623                 void Create_Block ()
 624                 {
 625                         original_block.SetHaveAnonymousMethods (Location, move_next_method);
 626                         block.SetHaveAnonymousMethods (Location, move_next_method);
 627
 628                         cc = original_block.CaptureContext;
 629
 630                         int first = IsStatic ? 0 : 1;
 631
 632                         ArrayList args = new ArrayList ();
 633                         if (!IsStatic) {
 634                                 Type t = this_type;
 635                                 args.Add (new Argument (
 636                                         new ThisParameterReference (t, Location)));
 637                                 cc.CaptureThis (move_next_method);
 638                         }
 639
 640                         args.Add (new Argument (new BoolLiteral (false)));
 641
 642                         for (int i = 0; i < parameters.Count; i++) {
 643                                 Type t = original_parameters.ParameterType (i);
 644                                 Type inflated = parameters.ParameterType (i);
 645                                 string name = parameters.ParameterName (i);
 646
 647                                 args.Add (new Argument (
 648                                         new SimpleParameterReference (t, first + i, Location)));
 649
 650                                 cc.AddParameterToContext (move_next_method, name, inflated, first + i);
 651                         }
 652
 653                         TypeExpr proxy_type;
 654                         if (generic_method != null) {
 655                                 TypeArguments new_args = new TypeArguments (Location);
 656                                 if (Parent.IsGeneric) {
 657                                         foreach (TypeParameter tparam in Parent.TypeParameters)
 658                                                 new_args.Add (new TypeParameterExpr (tparam, Location));
 659                                 }
 660                                 foreach (TypeParameter tparam in generic_method.TypeParameters)
 661                                         new_args.Add (new TypeParameterExpr (tparam, Location));
 662                                 ConstructedType ct = new ConstructedType (CurrentType, new_args, Location);
 663                                 proxy_type = ct.ResolveAsTypeTerminal (ec);
 664                         } else
 665                                 proxy_type = current_type;
 666
 667                         Expression new_expr = new New (proxy_type, args, Location);
 668                         block.AddStatement (new NoCheckReturn (new_expr, Location));
 669                 }
 670
 671                 void Define_Fields ()
 672                 {
 673                         pc_field = new Field (
 674                                 this, TypeManager.system_int32_expr, Modifiers.PRIVATE, "$PC",
 675                                 null, null, Location);
 676                         AddField (pc_field);
 677
 678                         current_field = new Field (
 679                                 this, iterator_type_expr, Modifiers.PRIVATE, "$current",
 680                                 null, null, Location);
 681                         AddField (current_field);
 682                 }
 683
 684                 void Define_Constructor ()
 685                 {
 686                         Parameters ctor_params;
 687
 688                         ArrayList list = new ArrayList ();
 689
 690                         if (!IsStatic)
 691                                 list.Add (new Parameter (
 692                                         new TypeExpression (this_type, Location),
 693                                         "this", Parameter.Modifier.NONE,
 694                                         null, Location));
 695                         list.Add (new Parameter (
 696                                 TypeManager.system_boolean_expr, "initialized",
 697                                 Parameter.Modifier.NONE, null, Location));
 698
 699                         Parameter[] old_fixed = parameters.Parameters.FixedParameters;
 700                         if (old_fixed != null)
 701                                 list.AddRange (old_fixed);
 702
 703                         Parameter[] fixed_params = new Parameter [list.Count];
 704                         list.CopyTo (fixed_params);
 705
 706                         ctor_params = new Parameters (fixed_params, parameters.Parameters.ArrayParameter);
 707
 708                         ctor = new Constructor (
 709                                 this, MemberName.Name, Modifiers.PUBLIC, ctor_params,
 710                                 new ConstructorBaseInitializer (null, Location),
 711                                 Location);
 712                         AddConstructor (ctor);
 713
 714                         ctor.Block = new ToplevelBlock (block, parameters.Parameters, Location);
 715
 716                         int first = IsStatic ? 2 : 3;
 717
 718                         State initial = is_enumerable ? State.Uninitialized : State.Running;
 719                         ctor.Block.AddStatement (new SetState (this, initial, Location));
 720
 721                         ctor.Block.AddStatement (new If (
 722                                 new SimpleParameterReference (
 723                                         TypeManager.bool_type, first - 1, Location),
 724                                 new SetState (this, State.Running, Location),
 725                                 Location));
 726
 727                         ctor.Block.AddStatement (new InitScope (this, Location));
 728                 }
 729
 730                 Statement Create_ThrowInvalidOperation ()
 731                 {
 732                         TypeExpr ex_type = new TypeExpression (
 733                                 TypeManager.invalid_operation_exception_type, Location);
 734
 735                         return new Throw (new New (ex_type, null, Location), Location);
 736                 }
 737
 738                 Statement Create_ThrowNotSupported ()
 739                 {
 740                         TypeExpr ex_type = new TypeExpression (
 741                                 TypeManager.not_supported_exception_type, Location);
 742
 743                         return new Throw (new New (ex_type, null, Location), Location);
 744                 }
 745
 746                 void Define_Current (bool is_generic)
 747                 {
 748                         MemberName left;
 749                         Expression type;
 750                         if (is_generic) {
 751                                 left = new MemberName (
 752                                         "System.Collections.Generic.IEnumerator",
 753                                         generic_args, Location);
 754                                 type = iterator_type_expr;
 755                         } else {
 756                                 left = new MemberName ("System.Collections.IEnumerator", Location);
 757                                 type = TypeManager.system_object_expr;
 758                         }
 759
 760                         MemberName name = new MemberName (left, "Current", null, Location);
 761
 762                         ToplevelBlock get_block = new ToplevelBlock (
 763                                 block, parameters.Parameters, Location);
 764
 765                         get_block.AddStatement (new If (
 766                                 new Binary (
 767                                         Binary.Operator.LessThanOrEqual,
 768                                         new FieldExpression (this, pc_field),
 769                                         new IntLiteral ((int) State.Running)),
 770                                 Create_ThrowInvalidOperation (),
 771                                 new Return (
 772                                         new FieldExpression (this, current_field), Location),
 773                                 Location));
 774
 775                         Accessor getter = new Accessor (get_block, 0, null, Location);
 776
 777                         Property current = new Property (
 778                                 this, type, 0, false, name, null, getter, null);
 779                         AddProperty (current);
 780                 }
 781
 782                 void Define_MoveNext ()
 783                 {
 784                         move_next_method = new MoveNextMethod (this, Location);
 785
 786                         original_block.ReParent (block, move_next_method);
 787
 788                         move_next_method.CreateMethod (ec);
 789
 790                         AddMethod (move_next_method.method);
 791                 }
 792
 793                 void Define_GetEnumerator (bool is_generic)
 794                 {
 795                         MemberName left;
 796                         Expression type;
 797                         if (is_generic) {
 798                                 left = new MemberName (
 799                                         "System.Collections.Generic.IEnumerable",
 800                                         generic_args, Location);
 801                                 type = generic_enumerator_type;
 802                         } else {
 803                                 left = new MemberName ("System.Collections.IEnumerable", Location);
 804                                 type = enumerator_type;
 805                         }
 806
 807                         MemberName name = new MemberName (left, "GetEnumerator", Location);
 808
 809                         Method get_enumerator = new Method (
 810                                 this, null, type, 0, false, name,
 811                                 Parameters.EmptyReadOnlyParameters, null);
 812                         AddMethod (get_enumerator);
 813
 814                         get_enumerator.Block = new ToplevelBlock (
 815                                 block, parameters.Parameters, Location);
 816
 817                         get_enumerator.Block.SetHaveAnonymousMethods (Location, move_next_method);
 818
 819                         Expression ce = new MemberAccess (
 820                                 new SimpleName ("System.Threading.Interlocked", Location),
 821                                 "CompareExchange", Location);
 822
 823                         Expression pc = new FieldExpression (this, pc_field);
 824                         Expression before = new IntLiteral ((int) State.Running);
 825                         Expression uninitialized = new IntLiteral ((int) State.Uninitialized);
 826
 827                         ArrayList args = new ArrayList ();
 828                         args.Add (new Argument (pc, Argument.AType.Ref));
 829                         args.Add (new Argument (before, Argument.AType.Expression));
 830                         args.Add (new Argument (uninitialized, Argument.AType.Expression));
 831
 832                         get_enumerator.Block.AddStatement (new If (
 833                                 new Binary (
 834                                         Binary.Operator.Equality,
 835                                         new Invocation (ce, args),
 836                                         uninitialized),
 837                                 new Return (new ThisParameterReference (type.Type, Location),
 838                                             Location),
 839                                 Location));
 840
 841                         args = new ArrayList ();
 842                         if (!IsStatic) {
 843                                 args.Add (new Argument (new CapturedThisReference (this, Location)));
 844                         }
 845
 846                         args.Add (new Argument (new BoolLiteral (true)));
 847
 848                         for (int i = 0; i < parameters.Count; i++) {
 849                                 Expression cp = new CapturedParameterReference (
 850                                         this, parameters.ParameterType (i),
 851                                         parameters.ParameterName (i), Location);
 852                                 args.Add (new Argument (cp));
 853                         }
 854
 855                         Expression new_expr = new New (current_type, args, Location);
 856                         get_enumerator.Block.AddStatement (new Return (new_expr, Location));
 857                 }
 858
 859                 protected class SimpleParameterReference : Expression
 860                 {
 861                         int idx;
 862
 863                         public SimpleParameterReference (Type type, int idx, Location loc)
 864                         {
 865                                 this.idx = idx;
 866                                 this.loc = loc;
 867                                 this.type = type;
 868                                 eclass = ExprClass.Variable;
 869                         }
 870
 871                         public override Expression DoResolve (EmitContext ec)
 872                         {
 873                                 return this;
 874                         }
 875
 876                         public override void Emit (EmitContext ec)
 877                         {
 878                                 DoEmit (ec);
 879                         }
 880
 881                         protected virtual void DoEmit (EmitContext ec)
 882                         {
 883                                 ParameterReference.EmitLdArg (ec.ig, idx);
 884                         }
 885                 }
 886
 887                 protected class ThisParameterReference : SimpleParameterReference, IMemoryLocation
 888                 {
 889                         public ThisParameterReference (Type type, Location loc)
 890                                 : base (type, 0, loc)
 891                         { }
 892
 893                         protected override void DoEmit (EmitContext ec)
 894                         {
 895                                 base.DoEmit (ec);
 896                                 if (ec.TypeContainer is Struct)
 897                                         ec.ig.Emit (OpCodes.Ldobj, type);
 898                         }
 899
 900                         public void AddressOf (EmitContext ec, AddressOp mode)
 901                         {
 902                                 if (ec.TypeContainer is Struct)
 903                                         ec.ig.Emit (OpCodes.Ldarga, 0);
 904                                 else
 905                                         ec.ig.Emit (OpCodes.Ldarg, 0);
 906                         }
 907                 }
 908
 909                 protected class CapturedParameterReference : Expression
 910                 {
 911                         Iterator iterator;
 912                         string name;
 913
 914                         public CapturedParameterReference (Iterator iterator, Type type,
 915                                                            string name, Location loc)
 916                         {
 917                                 this.iterator = iterator;
 918                                 this.loc = loc;
 919                                 this.type = type;
 920                                 this.name = name;
 921                                 eclass = ExprClass.Variable;
 922                         }
 923
 924                         public override Expression DoResolve (EmitContext ec)
 925                         {
 926                                 return this;
 927                         }
 928
 929                         public override void Emit (EmitContext ec)
 930                         {
 931                                 ec.CurrentAnonymousMethod = iterator.move_next_method;
 932
 933                                 iterator.cc.EmitParameter (ec, name);
 934                         }
 935                 }
 936
 937                 protected class CapturedThisReference : Expression
 938                 {
 939                         public CapturedThisReference (Iterator iterator, Location loc)
 940                         {
 941                                 this.loc = loc;
 942                                 this.type = iterator.this_type;
 943                                 eclass = ExprClass.Variable;
 944                         }
 945
 946                         public override Expression DoResolve (EmitContext ec)
 947                         {
 948                                 return this;
 949                         }
 950
 951                         public override void Emit (EmitContext ec)
 952                         {
 953                                 ec.EmitThis ();
 954                         }
 955                 }
 956
 957                 protected class FieldExpression : Expression
 958                 {
 959                         Iterator iterator;
 960                         Field field;
 961
 962                         public FieldExpression (Iterator iterator, Field field)
 963                         {
 964                                 this.iterator = iterator;
 965                                 this.field = field;
 966                                 this.loc = iterator.Location;
 967                         }
 968
 969                         public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
 970                         {
 971                                 FieldExpr fexpr = new FieldExpr (field.FieldBuilder, loc);
 972                                 fexpr.InstanceExpression = new ThisParameterReference (
 973                                         iterator.this_type, loc);
 974                                 return fexpr.ResolveLValue (ec, right_side, loc);
 975                         }
 976
 977                         public override Expression DoResolve (EmitContext ec)
 978                         {
 979                                 FieldExpr fexpr = new FieldExpr (field.FieldBuilder, loc);
 980                                 fexpr.InstanceExpression = new ThisParameterReference (
 981                                         iterator.this_type, loc);
 982                                 return fexpr.Resolve (ec);
 983                         }
 984
 985                         public override void Emit (EmitContext ec)
 986                         {
 987                                 throw new InvalidOperationException ();
 988                         }
 989                 }
 990
 991                 protected class MoveNextMethod : AnonymousContainer
 992                 {
 993                         Iterator iterator;
 994
 995                         public MoveNextMethod (Iterator iterator, Location loc)
 996                                 : base (iterator.parameters.Parameters, iterator.original_block, loc)
 997                         {
 998                                 this.iterator = iterator;
 999                         }
1000
1001                         protected override bool CreateMethodHost (EmitContext ec)
1002                         {
1003                                 method = new Method (
1004                                         iterator, null, TypeManager.system_boolean_expr,
1005                                         Modifiers.PUBLIC, false, new MemberName ("MoveNext", loc),
1006                                         Parameters.EmptyReadOnlyParameters, null);
1007
1008                                 method.Block = Block;
1009
1010                                 MoveNextStatement inline = new MoveNextStatement (iterator, loc);
1011                                 Block.AddStatement (inline);
1012
1013                                 return true;
1014                         }
1015
1016                         public bool CreateMethod (EmitContext ec)
1017                         {
1018                                 return CreateMethodHost (ec);
1019                         }
1020
1021                         public override Iterator Iterator {
1022                                 get { return iterator; }
1023                         }
1024
1025                         public override bool IsIterator {
1026                                 get { return true; }
1027                         }
1028
1029                         public override void CreateScopeType (EmitContext ec, ScopeInfo scope)
1030                         {
1031                                 scope.ScopeTypeBuilder = iterator.TypeBuilder;
1032                                 scope.ScopeConstructor = iterator.ctor.ConstructorBuilder;
1033                         }
1034
1035                         public override void Emit (EmitContext ec)
1036                         {
1037                                 throw new InternalErrorException ();
1038                         }
1039                 }
1040
1041                 protected class MoveNextStatement : Statement {
1042                         Iterator iterator;
1043
1044                         public MoveNextStatement (Iterator iterator, Location loc)
1045                         {
1046                                 this.loc = loc;
1047                                 this.iterator = iterator;
1048                         }
1049
1050                         public override bool Resolve (EmitContext ec)
1051                         {
1052                                 return true;
1053                         }
1054
1055                         protected override void DoEmit (EmitContext ec)
1056                         {
1057                                 ec.CurrentAnonymousMethod = iterator.move_next_method;
1058                                 ec.InIterator = true;
1059
1060                                 iterator.EmitMoveNext (ec);
1061                         }
1062                 }
1063
1064                 protected class DisposeMethod : Statement {
1065                         Iterator iterator;
1066
1067                         public DisposeMethod (Iterator iterator, Location loc)
1068                         {
1069                                 this.loc = loc;
1070                                 this.iterator = iterator;
1071                         }
1072
1073                         public override bool Resolve (EmitContext ec)
1074                         {
1075                                 return true;
1076                         }
1077
1078                         protected override void DoEmit (EmitContext ec)
1079                         {
1080                                 iterator.EmitDispose (ec);
1081                         }
1082                 }
1083
1084                 protected class StatementList : Statement {
1085                         ArrayList statements;
1086
1087                         public StatementList (Location loc)
1088                         {
1089                                 this.loc = loc;
1090                                 statements = new ArrayList ();
1091                         }
1092
1093                         public void Add (Statement statement)
1094                         {
1095                                 statements.Add (statement);
1096                         }
1097
1098                         public override bool Resolve (EmitContext ec)
1099                         {
1100                                 foreach (Statement stmt in statements) {
1101                                         if (!stmt.Resolve (ec))
1102                                                 return false;
1103                                 }
1104
1105                                 return true;
1106                         }
1107
1108                         protected override void DoEmit (EmitContext ec)
1109                         {
1110                                 foreach (Statement stmt in statements)
1111                                         stmt.Emit (ec);
1112                         }
1113                 }
1114
1115                 protected class SetState : Statement
1116                 {
1117                         Iterator iterator;
1118                         State state;
1119
1120                         public SetState (Iterator iterator, State state, Location loc)
1121                         {
1122                                 this.iterator = iterator;
1123                                 this.state = state;
1124                                 this.loc = loc;
1125                         }
1126
1127                         public override bool Resolve (EmitContext ec)
1128                         {
1129                                 return true;
1130                         }
1131
1132                         protected override void DoEmit (EmitContext ec)
1133                         {
1134                                 ec.ig.Emit (OpCodes.Ldarg_0);
1135                                 IntConstant.EmitInt (ec.ig, (int) state);
1136                                 ec.ig.Emit (OpCodes.Stfld, iterator.pc_field.FieldBuilder);
1137                         }
1138                 }
1139
1140                 protected class InitScope : Statement
1141                 {
1142                         Iterator iterator;
1143
1144                         public InitScope (Iterator iterator, Location loc)
1145                         {
1146                                 this.iterator = iterator;
1147                                 this.loc = loc;
1148                         }
1149
1150                         public override bool Resolve (EmitContext ec)
1151                         {
1152                                 return true;
1153                         }
1154
1155                         protected override void DoEmit (EmitContext ec)
1156                         {
1157                                 iterator.cc.EmitInitScope (ec);
1158                         }
1159                 }
1160
1161                 void Define_Reset ()
1162                 {
1163                         Method reset = new Method (
1164                                 this, null, TypeManager.system_void_expr, Modifiers.PUBLIC,
1165                                 false, new MemberName ("Reset", Location),
1166                                 Parameters.EmptyReadOnlyParameters, null);
1167                         AddMethod (reset);
1168
1169                         reset.Block = new ToplevelBlock (Location);
1170                         reset.Block = new ToplevelBlock (block, parameters.Parameters, Location);
1171                         reset.Block.SetHaveAnonymousMethods (Location, move_next_method);
1172
1173                         reset.Block.AddStatement (Create_ThrowNotSupported ());
1174                 }
1175
1176                 void Define_Dispose ()
1177                 {
1178                         dispose = new Method (
1179                                 this, null, TypeManager.system_void_expr, Modifiers.PUBLIC,
1180                                 false, new MemberName ("Dispose", Location),
1181                                 Parameters.EmptyReadOnlyParameters, null);
1182                         AddMethod (dispose);
1183
1184                         dispose.Block = new ToplevelBlock (block, parameters.Parameters, Location);
1185                         dispose.Block.SetHaveAnonymousMethods (Location, move_next_method);
1186
1187                         dispose.Block.AddStatement (new DisposeMethod (this, Location));
1188                 }
1189
1190                 public Type IteratorType {
1191                         get { return iterator_type_expr.Type; }
1192                 }
1193
1194                 //
1195                 // This return statement tricks return into not flagging an error for being
1196                 // used in a Yields method
1197                 //
1198                 class NoCheckReturn : Statement {
1199                         public Expression Expr;
1200
1201                         public NoCheckReturn (Expression expr, Location l)
1202                         {
1203                                 Expr = expr;
1204                                 loc = l;
1205                         }
1206
1207                         public override bool Resolve (EmitContext ec)
1208                         {
1209                                 Expr = Expr.Resolve (ec);
1210                                 if (Expr == null)
1211                                         return false;
1212
1213                                 ec.CurrentBranching.CurrentUsageVector.Return ();
1214
1215                                 return true;
1216                         }
1217
1218                         protected override void DoEmit (EmitContext ec)
1219                         {
1220                                 Expr.Emit (ec);
1221                                 ec.ig.Emit (OpCodes.Ret);
1222                         }
1223                 }
1224
1225                 bool CheckType ()
1226                 {
1227                         Type ret = orig_method.ReturnType;
1228
1229                         if (ret == TypeManager.ienumerable_type) {
1230                                 original_iterator_type = TypeManager.object_type;
1231                                 is_enumerable = true;
1232                                 return true;
1233                         }
1234                         if (ret == TypeManager.ienumerator_type) {
1235                                 original_iterator_type = TypeManager.object_type;
1236                                 is_enumerable = false;
1237                                 return true;
1238                         }
1239
1240                         if (!ret.IsGenericInstance)
1241                                 return false;
1242
1243                         Type[] args = TypeManager.GetTypeArguments (ret);
1244                         if (args.Length != 1)
1245                                 return false;
1246
1247                         Type gt = ret.GetGenericTypeDefinition ();
1248                         if (gt == TypeManager.generic_ienumerable_type) {
1249                                 original_iterator_type = args [0];
1250                                 is_enumerable = true;
1251                                 return true;
1252                         } else if (gt == TypeManager.generic_ienumerator_type) {
1253                                 original_iterator_type = args [0];
1254                                 is_enumerable = false;
1255                                 return true;
1256                         }
1257
1258                         return false;
1259                 }
1260         }
1261 }
1262