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, bool isYieldBreak)
  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
  55                         AnonymousContainer am = ec.CurrentAnonymousMethod;
  56                         if ((am != null) && !am.IsIterator){
  57                                 Report.Error (1621, loc, "The yield statement cannot be used inside anonymous method blocks");
  58                                 return false;
  59                         }
  60
  61                         if (ec.CurrentBranching.InTryWithCatch () && (!isYieldBreak || !ec.InCatch)) {
  62                                 if (!ec.InCatch)
  63                                         Report.Error (1626, loc, "Cannot yield a value in the body of a " +
  64                                         "try block with a catch clause");
  65                                 else
  66                                         Report.Error (1631, loc, "Cannot yield a value in the body of a catch clause");
  67                                 return false;
  68                         }
  69                         return true;
  70                 }
  71
  72                 public override bool Resolve (EmitContext ec)
  73                 {
  74                         expr = expr.Resolve (ec);
  75                         if (expr == null)
  76                                 return false;
  77
  78                         if (!CheckContext (ec, loc, false))
  79                                 return false;
  80
  81                         Iterator iterator = ec.CurrentIterator;
  82
  83                         if (expr.Type != iterator.IteratorType){
  84                                 expr = Convert.ImplicitConversionRequired (
  85                                         ec, expr, iterator.IteratorType, loc);
  86                                 if (expr == null)
  87                                         return false;
  88                         }
  89
  90                         ec.CurrentBranching.StealFinallyClauses (ref finally_blocks);
  91                         return true;
  92                 }
  93
  94                 protected override void DoEmit (EmitContext ec)
  95                 {
  96                         ec.CurrentIterator.MarkYield (ec, expr, finally_blocks);
  97                 }
  98         }
  99
 100         public class YieldBreak : Statement {
 101
 102                 public YieldBreak (Location l)
 103                 {
 104                         loc = l;
 105                 }
 106
 107                 public override bool Resolve (EmitContext ec)
 108                 {
 109                         if (!Yield.CheckContext (ec, loc, true))
 110                                 return false;
 111
 112                         ec.CurrentBranching.CurrentUsageVector.Goto ();
 113                         return true;
 114                 }
 115
 116                 protected override void DoEmit (EmitContext ec)
 117                 {
 118                         ec.CurrentIterator.EmitYieldBreak (ec.ig);
 119                 }
 120         }
 121
 122         public class Iterator : Class {
 123                 protected ToplevelBlock original_block;
 124                 protected ToplevelBlock block;
 125
 126                 Type original_iterator_type;
 127                 TypeExpr iterator_type_expr;
 128                 bool is_enumerable;
 129                 public readonly bool IsStatic;
 130
 131                 //
 132                 // The state as we generate the iterator
 133                 //
 134                 Label move_next_ok, move_next_error;
 135                 ArrayList resume_points = new ArrayList ();
 136                 int pc;
 137
 138                 //
 139                 // Context from the original method
 140                 //
 141                 GenericMethod generic_method;
 142                 TypeContainer container;
 143                 TypeExpr current_type;
 144                 Type this_type;
 145                 Parameters parameters;
 146                 Parameters original_parameters;
 147                 IMethodData orig_method;
 148
 149                 MethodInfo dispose_method;
 150                 MoveNextMethod move_next_method;
 151                 Constructor ctor;
 152                 CaptureContext cc;
 153
 154                 Expression enumerator_type;
 155                 Expression enumerable_type;
 156                 Expression generic_enumerator_type;
 157                 Expression generic_enumerable_type;
 158                 TypeArguments generic_args;
 159                 EmitContext ec;
 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);
 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, DeclSpace parent, GenericMethod generic,
 360                                  int modifiers)
 361                         : base (parent.NamespaceEntry, parent,
 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 = ((TypeContainer) parent).PartialContainer;
 369                         this.original_parameters = m_container.ParameterInfo;
 370                         this.original_block = orig_method.Block;
 371                         this.block = new ToplevelBlock (orig_method.Block, 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, 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.IsGenericType) {
 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, false).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                 Parameters InflateParameters (Parameters parameters, EmitContext ec)
 534                 {
 535                         int count = parameters.FixedParameters.Length;
 536                         if (count == 0)
 537                                 return Parameters.EmptyReadOnlyParameters;
 538                         Parameter[] fixed_params = new Parameter [count];
 539                         for (int i = 0; i < count; i++)
 540                                 fixed_params [i] = InflateParameter (parameters.FixedParameters [i]);
 541
 542                         return new Parameters (fixed_params, parameters.HasArglist);
 543                 }
 544
 545                 public override TypeExpr [] GetClassBases (out TypeExpr base_class)
 546                 {
 547                         iterator_type_expr = InflateType (original_iterator_type);
 548
 549                         generic_args = new TypeArguments (Location);
 550                         generic_args.Add (iterator_type_expr);
 551
 552                         ArrayList list = new ArrayList ();
 553                         if (is_enumerable) {
 554                                 enumerable_type = new TypeExpression (
 555                                         TypeManager.ienumerable_type, Location);
 556                                 list.Add (enumerable_type);
 557
 558                                 generic_enumerable_type = new ConstructedType (
 559                                         TypeManager.generic_ienumerable_type,
 560                                         generic_args, Location);
 561                                 list.Add (generic_enumerable_type);
 562                         }
 563
 564                         enumerator_type = new TypeExpression (
 565                                 TypeManager.ienumerator_type, Location);
 566                         list.Add (enumerator_type);
 567
 568                         list.Add (new TypeExpression (TypeManager.idisposable_type, Location));
 569
 570                         generic_enumerator_type = new ConstructedType (
 571                                 TypeManager.generic_ienumerator_type,
 572                                 generic_args, Location);
 573                         list.Add (generic_enumerator_type);
 574
 575                         Bases = list;
 576
 577                         return base.GetClassBases (out base_class);
 578                 }
 579
 580                 //
 581                 // Returns the new block for the method, or null on failure
 582                 //
 583                 protected override bool DefineNestedTypes ()
 584                 {
 585                         if (CurrentType != null)
 586                                 current_type = new TypeExpression (CurrentType, Location);
 587                         else
 588                                 current_type = new TypeExpression (TypeBuilder, Location);
 589
 590                         if (IsGeneric) {
 591                                 foreach (TypeParameter tparam in TypeParameters)
 592                                         tparam.InflateConstraints (current_type.Type);
 593                         }
 594
 595                         parameters = InflateParameters (original_parameters, ec);
 596                         if (!parameters.Resolve (ec)) {
 597                                 // TODO:
 598                         }
 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, Location)));
 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, false);
 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, "$PC",
 675                                 null, Location);
 676                         AddField (pc_field);
 677
 678                         current_field = new Field (
 679                                 this, iterator_type_expr, Modifiers.PRIVATE, "$current",
 680                                 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.bool_type, "initialized",
 697                                 Parameter.Modifier.NONE, null, Location));
 698
 699                         Parameter[] old_fixed = parameters.FixedParameters;
 700                         list.AddRange (old_fixed);
 701
 702                         Parameter[] fixed_params = new Parameter [list.Count];
 703                         list.CopyTo (fixed_params);
 704
 705                         ctor_params = new Parameters (fixed_params);
 706
 707                         ctor = new Constructor (
 708                                 this, MemberName.Name, Modifiers.PUBLIC, ctor_params,
 709                                 new GeneratedBaseInitializer (Location),
 710                                 Location);
 711                         AddConstructor (ctor);
 712
 713                         ctor.Block = new ToplevelBlock (block, parameters, Location);
 714
 715                         int first = IsStatic ? 2 : 3;
 716
 717                         State initial = is_enumerable ? State.Uninitialized : State.Running;
 718                         ctor.Block.AddStatement (new SetState (this, initial, Location));
 719
 720                         ctor.Block.AddStatement (new If (
 721                                 new SimpleParameterReference (
 722                                         TypeManager.bool_type, first - 1, Location),
 723                                 new SetState (this, State.Running, Location),
 724                                 Location));
 725
 726                         ctor.Block.AddStatement (new InitScope (this, Location));
 727                 }
 728
 729                 Statement Create_ThrowInvalidOperation ()
 730                 {
 731                         TypeExpr ex_type = new TypeExpression (
 732                                 TypeManager.invalid_operation_exception_type, Location);
 733
 734                         return new Throw (new New (ex_type, null, Location), Location);
 735                 }
 736
 737                 Statement Create_ThrowNotSupported ()
 738                 {
 739                         TypeExpr ex_type = new TypeExpression (
 740                                 TypeManager.not_supported_exception_type, Location);
 741
 742                         return new Throw (new New (ex_type, null, Location), Location);
 743                 }
 744
 745                 void Define_Current (bool is_generic)
 746                 {
 747                         MemberName left;
 748                         Expression type;
 749                         if (is_generic) {
 750                                 left = new MemberName (
 751                                         "System.Collections.Generic.IEnumerator",
 752                                         generic_args, Location);
 753                                 type = iterator_type_expr;
 754                         } else {
 755                                 left = new MemberName ("System.Collections.IEnumerator", Location);
 756                                 type = TypeManager.system_object_expr;
 757                         }
 758
 759                         MemberName name = new MemberName (left, "Current", null, Location);
 760
 761                         ToplevelBlock get_block = new ToplevelBlock (
 762                                 block, parameters, Location);
 763
 764                         get_block.AddStatement (new If (
 765                                 new Binary (
 766                                         Binary.Operator.LessThanOrEqual,
 767                                         new FieldExpression (this, pc_field),
 768                                         new IntLiteral ((int) State.Running, pc_field.Location)),
 769                                 Create_ThrowInvalidOperation (),
 770                                 new Return (
 771                                         new FieldExpression (this, current_field), Location),
 772                                 Location));
 773
 774                         Accessor getter = new Accessor (get_block, 0, null, Location);
 775
 776                         Property current = new Property (
 777                                 this, type, 0, false, name, null, getter, null);
 778                         AddProperty (current);
 779                 }
 780
 781                 void Define_MoveNext ()
 782                 {
 783                         move_next_method = new MoveNextMethod (this, Location);
 784
 785                         original_block.ReParent (block, move_next_method);
 786
 787                         move_next_method.CreateMethod (ec);
 788
 789                         AddMethod (move_next_method.method);
 790                 }
 791
 792                 void Define_GetEnumerator (bool is_generic)
 793                 {
 794                         MemberName left;
 795                         Expression type;
 796                         if (is_generic) {
 797                                 left = new MemberName (
 798                                         "System.Collections.Generic.IEnumerable",
 799                                         generic_args, Location);
 800                                 type = generic_enumerator_type;
 801                         } else {
 802                                 left = new MemberName ("System.Collections.IEnumerable", Location);
 803                                 type = enumerator_type;
 804                         }
 805
 806                         MemberName name = new MemberName (left, "GetEnumerator", Location);
 807
 808                         Method get_enumerator = new Method (
 809                                 this, null, type, 0, false, name,
 810                                 Parameters.EmptyReadOnlyParameters, null);
 811
 812                         //
 813                         // We call append instead of add, as we need to make sure that
 814                         // this method is resolved after the MoveNext method, as that one
 815                         // triggers the computation of the AnonymousMethod Scope, which is
 816                         // required during the code generation of the enumerator
 817                         //
 818                         AppendMethod (get_enumerator);
 819
 820                         get_enumerator.Block = new ToplevelBlock (
 821                                 block, parameters, Location);
 822
 823                         get_enumerator.Block.SetHaveAnonymousMethods (Location, move_next_method);
 824
 825                         Expression ce = new MemberAccess (
 826                                 new SimpleName ("System.Threading.Interlocked", Location),
 827                                 "CompareExchange", Location);
 828
 829                         Expression pc = new FieldExpression (this, pc_field);
 830                         Expression before = new IntLiteral ((int) State.Running, Location);
 831                         Expression uninitialized = new IntLiteral ((int) State.Uninitialized, Location);
 832
 833                         ArrayList args = new ArrayList ();
 834                         args.Add (new Argument (pc, Argument.AType.Ref));
 835                         args.Add (new Argument (before, Argument.AType.Expression));
 836                         args.Add (new Argument (uninitialized, Argument.AType.Expression));
 837
 838                         get_enumerator.Block.AddStatement (new If (
 839                                 new Binary (
 840                                         Binary.Operator.Equality,
 841                                         new Invocation (ce, args),
 842                                         uninitialized),
 843                                 new Return (new ThisParameterReference (type.Type, Location),
 844                                             Location),
 845                                 Location));
 846
 847                         args = new ArrayList ();
 848                         if (!IsStatic) {
 849                                 args.Add (new Argument (new CapturedThisReference (this, Location)));
 850                         }
 851
 852                         args.Add (new Argument (new BoolLiteral (true, Location)));
 853
 854                         for (int i = 0; i < parameters.Count; i++) {
 855                                 Expression cp = new CapturedParameterReference (
 856                                         this, parameters.ParameterType (i),
 857                                         parameters.ParameterName (i), Location);
 858                                 args.Add (new Argument (cp));
 859                         }
 860
 861                         Expression new_expr = new New (current_type, args, Location);
 862                         get_enumerator.Block.AddStatement (new Return (new_expr, Location));
 863                 }
 864
 865                 protected class SimpleParameterReference : Expression
 866                 {
 867                         int idx;
 868
 869                         public SimpleParameterReference (Type type, int idx, Location loc)
 870                         {
 871                                 this.idx = idx;
 872                                 this.loc = loc;
 873                                 this.type = type;
 874                                 eclass = ExprClass.Variable;
 875                         }
 876
 877                         public override Expression DoResolve (EmitContext ec)
 878                         {
 879                                 return this;
 880                         }
 881
 882                         public override void Emit (EmitContext ec)
 883                         {
 884                                 DoEmit (ec);
 885                         }
 886
 887                         protected virtual void DoEmit (EmitContext ec)
 888                         {
 889                                 ParameterReference.EmitLdArg (ec.ig, idx);
 890                         }
 891                 }
 892
 893                 protected class ThisParameterReference : SimpleParameterReference, IMemoryLocation
 894                 {
 895                         public ThisParameterReference (Type type, Location loc)
 896                                 : base (type, 0, loc)
 897                         { }
 898
 899                         protected override void DoEmit (EmitContext ec)
 900                         {
 901                                 base.DoEmit (ec);
 902                                 if (ec.TypeContainer is Struct)
 903                                         ec.ig.Emit (OpCodes.Ldobj, type);
 904                         }
 905
 906                         public void AddressOf (EmitContext ec, AddressOp mode)
 907                         {
 908                                 if (ec.TypeContainer is Struct)
 909                                         ec.ig.Emit (OpCodes.Ldarga, 0);
 910                                 else
 911                                         ec.ig.Emit (OpCodes.Ldarg, 0);
 912                         }
 913                 }
 914
 915                 protected class CapturedParameterReference : Expression
 916                 {
 917                         Iterator iterator;
 918                         string name;
 919
 920                         public CapturedParameterReference (Iterator iterator, Type type,
 921                                                            string name, Location loc)
 922                         {
 923                                 this.iterator = iterator;
 924                                 this.loc = loc;
 925                                 this.type = type;
 926                                 this.name = name;
 927                                 eclass = ExprClass.Variable;
 928                         }
 929
 930                         public override Expression DoResolve (EmitContext ec)
 931                         {
 932                                 return this;
 933                         }
 934
 935                         public override void Emit (EmitContext ec)
 936                         {
 937                                 ec.CurrentAnonymousMethod = iterator.move_next_method;
 938
 939                                 LocalTemporary dummy = null;
 940
 941                                 iterator.cc.EmitParameter (ec, name, false, false, ref dummy);
 942                         }
 943                 }
 944
 945                 protected class CapturedThisReference : Expression
 946                 {
 947                         public CapturedThisReference (Iterator iterator, Location loc)
 948                         {
 949                                 this.loc = loc;
 950                                 this.type = iterator.this_type;
 951                                 eclass = ExprClass.Variable;
 952                         }
 953
 954                         public override Expression DoResolve (EmitContext ec)
 955                         {
 956                                 return this;
 957                         }
 958
 959                         public override void Emit (EmitContext ec)
 960                         {
 961                                 ec.EmitThis (false);
 962                         }
 963                 }
 964
 965                 protected class FieldExpression : Expression
 966                 {
 967                         Iterator iterator;
 968                         Field field;
 969
 970                         public FieldExpression (Iterator iterator, Field field)
 971                         {
 972                                 this.iterator = iterator;
 973                                 this.field = field;
 974                                 this.loc = iterator.Location;
 975                         }
 976
 977                         public override Expression DoResolveLValue (EmitContext ec, Expression right_side)
 978                         {
 979                                 FieldExpr fexpr = new FieldExpr (field.FieldBuilder, loc);
 980                                 fexpr.InstanceExpression = new ThisParameterReference (
 981                                         iterator.this_type, loc);
 982                                 return fexpr.ResolveLValue (ec, right_side, loc);
 983                         }
 984
 985                         public override Expression DoResolve (EmitContext ec)
 986                         {
 987                                 FieldExpr fexpr = new FieldExpr (field.FieldBuilder, loc);
 988                                 fexpr.InstanceExpression = new ThisParameterReference (
 989                                         iterator.this_type, loc);
 990                                 return fexpr.Resolve (ec);
 991                         }
 992
 993                         public override void Emit (EmitContext ec)
 994                         {
 995                                 throw new InvalidOperationException ();
 996                         }
 997                 }
 998
 999                 protected class MoveNextMethod : AnonymousContainer
1000                 {
1001                         Iterator iterator;
1002
1003                         public MoveNextMethod (Iterator iterator, Location loc)
1004                                 : base (iterator.parameters, iterator.original_block, loc)
1005                         {
1006                                 this.iterator = iterator;
1007                         }
1008
1009                         protected override bool CreateMethodHost (EmitContext ec)
1010                         {
1011                                 method = new Method (
1012                                         iterator, null, TypeManager.system_boolean_expr,
1013                                         Modifiers.PUBLIC, false, new MemberName ("MoveNext", loc),
1014                                         Parameters.EmptyReadOnlyParameters, null);
1015
1016                                 method.Block = Block;
1017
1018                                 MoveNextStatement inline = new MoveNextStatement (iterator, loc);
1019                                 Block.AddStatement (inline);
1020
1021                                 return true;
1022                         }
1023
1024                         public bool CreateMethod (EmitContext ec)
1025                         {
1026                                 return CreateMethodHost (ec);
1027                         }
1028
1029                         public override Iterator Iterator {
1030                                 get { return iterator; }
1031                         }
1032
1033                         public void ComputeHost ()
1034                         {
1035                                 ComputeMethodHost ();
1036                         }
1037
1038                         public override bool IsIterator {
1039                                 get { return true; }
1040                         }
1041
1042                         public override void CreateScopeType (EmitContext ec, ScopeInfo scope)
1043                         {
1044                                 scope.ScopeTypeBuilder = iterator.TypeBuilder;
1045                                 scope.ScopeConstructor = iterator.ctor.ConstructorBuilder;
1046                         }
1047
1048                         public override void Emit (EmitContext ec)
1049                         {
1050                                 throw new InternalErrorException ();
1051                         }
1052                 }
1053
1054                 protected class MoveNextStatement : Statement {
1055                         Iterator iterator;
1056
1057                         public MoveNextStatement (Iterator iterator, Location loc)
1058                         {
1059                                 this.loc = loc;
1060                                 this.iterator = iterator;
1061                         }
1062
1063                         public override bool Resolve (EmitContext ec)
1064                         {
1065                                 return true;
1066                         }
1067
1068                         protected override void DoEmit (EmitContext ec)
1069                         {
1070                                 iterator.move_next_method.ComputeHost ();
1071                                 ec.CurrentAnonymousMethod = iterator.move_next_method;
1072                                 ec.InIterator = true;
1073
1074                                 iterator.EmitMoveNext (ec);
1075                         }
1076                 }
1077
1078                 protected class DisposeMethod : Statement {
1079                         Iterator iterator;
1080
1081                         public DisposeMethod (Iterator iterator, Location loc)
1082                         {
1083                                 this.loc = loc;
1084                                 this.iterator = iterator;
1085                         }
1086
1087                         public override bool Resolve (EmitContext ec)
1088                         {
1089                                 return true;
1090                         }
1091
1092                         protected override void DoEmit (EmitContext ec)
1093                         {
1094                                 iterator.EmitDispose (ec);
1095                         }
1096                 }
1097
1098                 protected class StatementList : Statement {
1099                         ArrayList statements;
1100
1101                         public StatementList (Location loc)
1102                         {
1103                                 this.loc = loc;
1104                                 statements = new ArrayList ();
1105                         }
1106
1107                         public void Add (Statement statement)
1108                         {
1109                                 statements.Add (statement);
1110                         }
1111
1112                         public override bool Resolve (EmitContext ec)
1113                         {
1114                                 foreach (Statement stmt in statements) {
1115                                         if (!stmt.Resolve (ec))
1116                                                 return false;
1117                                 }
1118
1119                                 return true;
1120                         }
1121
1122                         protected override void DoEmit (EmitContext ec)
1123                         {
1124                                 foreach (Statement stmt in statements)
1125                                         stmt.Emit (ec);
1126                         }
1127                 }
1128
1129                 protected class SetState : Statement
1130                 {
1131                         Iterator iterator;
1132                         State state;
1133
1134                         public SetState (Iterator iterator, State state, Location loc)
1135                         {
1136                                 this.iterator = iterator;
1137                                 this.state = state;
1138                                 this.loc = loc;
1139                         }
1140
1141                         public override bool Resolve (EmitContext ec)
1142                         {
1143                                 return true;
1144                         }
1145
1146                         protected override void DoEmit (EmitContext ec)
1147                         {
1148                                 ec.ig.Emit (OpCodes.Ldarg_0);
1149                                 IntConstant.EmitInt (ec.ig, (int) state);
1150                                 ec.ig.Emit (OpCodes.Stfld, iterator.pc_field.FieldBuilder);
1151                         }
1152                 }
1153
1154                 protected class InitScope : Statement
1155                 {
1156                         Iterator iterator;
1157
1158                         public InitScope (Iterator iterator, Location loc)
1159                         {
1160                                 this.iterator = iterator;
1161                                 this.loc = loc;
1162                         }
1163
1164                         public override bool Resolve (EmitContext ec)
1165                         {
1166                                 return true;
1167                         }
1168
1169                         protected override void DoEmit (EmitContext ec)
1170                         {
1171                                 iterator.cc.EmitInitScope (ec);
1172                         }
1173                 }
1174
1175                 void Define_Reset ()
1176                 {
1177                         Method reset = new Method (
1178                                 this, null, TypeManager.system_void_expr, Modifiers.PUBLIC,
1179                                 false, new MemberName ("Reset", Location),
1180                                 Parameters.EmptyReadOnlyParameters, null);
1181                         AddMethod (reset);
1182
1183                         reset.Block = new ToplevelBlock (Location);
1184                         reset.Block = new ToplevelBlock (block, parameters, Location);
1185                         reset.Block.SetHaveAnonymousMethods (Location, move_next_method);
1186
1187                         reset.Block.AddStatement (Create_ThrowNotSupported ());
1188                 }
1189
1190                 void Define_Dispose ()
1191                 {
1192                         dispose = new Method (
1193                                 this, null, TypeManager.system_void_expr, Modifiers.PUBLIC,
1194                                 false, new MemberName ("Dispose", Location),
1195                                 Parameters.EmptyReadOnlyParameters, null);
1196                         AddMethod (dispose);
1197
1198                         dispose.Block = new ToplevelBlock (block, parameters, Location);
1199                         dispose.Block.SetHaveAnonymousMethods (Location, move_next_method);
1200
1201                         dispose.Block.AddStatement (new DisposeMethod (this, Location));
1202                 }
1203
1204                 public Type IteratorType {
1205                         get { return iterator_type_expr.Type; }
1206                 }
1207
1208                 //
1209                 // This return statement tricks return into not flagging an error for being
1210                 // used in a Yields method
1211                 //
1212                 class NoCheckReturn : Statement {
1213                         public Expression Expr;
1214
1215                         public NoCheckReturn (Expression expr, Location l)
1216                         {
1217                                 Expr = expr;
1218                                 loc = l;
1219                         }
1220
1221                         public override bool Resolve (EmitContext ec)
1222                         {
1223                                 Expr = Expr.Resolve (ec);
1224                                 if (Expr == null)
1225                                         return false;
1226
1227                                 ec.CurrentBranching.CurrentUsageVector.Return ();
1228
1229                                 return true;
1230                         }
1231
1232                         protected override void DoEmit (EmitContext ec)
1233                         {
1234                                 Expr.Emit (ec);
1235                                 ec.ig.Emit (OpCodes.Ret);
1236                         }
1237                 }
1238
1239                 bool CheckType ()
1240                 {
1241                         Type ret = orig_method.ReturnType;
1242
1243                         if (ret == TypeManager.ienumerable_type) {
1244                                 original_iterator_type = TypeManager.object_type;
1245                                 is_enumerable = true;
1246                                 return true;
1247                         }
1248                         if (ret == TypeManager.ienumerator_type) {
1249                                 original_iterator_type = TypeManager.object_type;
1250                                 is_enumerable = false;
1251                                 return true;
1252                         }
1253
1254                         if (!ret.IsGenericType)
1255                                 return false;
1256
1257                         Type[] args = TypeManager.GetTypeArguments (ret);
1258                         if (args.Length != 1)
1259                                 return false;
1260
1261                         Type gt = ret.GetGenericTypeDefinition ();
1262                         if (gt == TypeManager.generic_ienumerable_type) {
1263                                 original_iterator_type = args [0];
1264                                 is_enumerable = true;
1265                                 return true;
1266                         } else if (gt == TypeManager.generic_ienumerator_type) {
1267                                 original_iterator_type = args [0];
1268                                 is_enumerable = false;
1269                                 return true;
1270                         }
1271
1272                         return false;
1273                 }
1274         }
1275 }
1276