mcs/mcs/iterators.cs

   1 //
   2 // iterators.cs: Support for implementing iterators
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@gmail.com)
   7 //
   8 // Dual licensed under the terms of the MIT X11 or GNU GPL
   9 // Copyright 2003 Ximian, Inc.
  10 // Copyright 2003-2008 Novell, Inc.
  11 // Copyright 2011 Xamarin Inc.
  12 //
  13
  14 using System;
  15 using System.Collections.Generic;
  16 using Mono.CompilerServices.SymbolWriter;
  17
  18 #if STATIC
  19 using IKVM.Reflection.Emit;
  20 #else
  21 using System.Reflection.Emit;
  22 #endif
  23
  24 namespace Mono.CSharp
  25 {
  26         public abstract class YieldStatement<T> : ResumableStatement where T : StateMachineInitializer
  27         {
  28                 protected Expression expr;
  29                 protected bool unwind_protect;
  30                 protected T machine_initializer;
  31                 int resume_pc;
  32                 ExceptionStatement inside_try_block;
  33
  34                 protected YieldStatement (Expression expr, Location l)
  35                 {
  36                         this.expr = expr;
  37                         loc = l;
  38                 }
  39
  40                 public Expression Expr {
  41                         get { return this.expr; }
  42                 }
  43
  44                 protected override void CloneTo (CloneContext clonectx, Statement t)
  45                 {
  46                         var target = (YieldStatement<T>) t;
  47                         target.expr = expr.Clone (clonectx);
  48                 }
  49
  50                 protected override void DoEmit (EmitContext ec)
  51                 {
  52                         machine_initializer.InjectYield (ec, expr, resume_pc, unwind_protect, resume_point);
  53                 }
  54
  55                 protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
  56                 {
  57                         expr.FlowAnalysis (fc);
  58
  59                         RegisterResumePoint ();
  60
  61                         return false;
  62                 }
  63
  64                 public override bool Resolve (BlockContext bc)
  65                 {
  66                         expr = expr.Resolve (bc);
  67                         if (expr == null)
  68                                 return false;
  69
  70                         machine_initializer = bc.CurrentAnonymousMethod as T;
  71                         inside_try_block = bc.CurrentTryBlock;
  72                         return true;
  73                 }
  74
  75                 public void RegisterResumePoint ()
  76                 {
  77                         if (resume_pc != 0)
  78                                 return;
  79
  80                         if (inside_try_block == null) {
  81                                 resume_pc = machine_initializer.AddResumePoint (this);
  82                         } else {
  83                                 resume_pc = inside_try_block.AddResumePoint (this, resume_pc, machine_initializer);
  84                                 unwind_protect = true;
  85                                 inside_try_block = null;
  86                         }
  87                 }
  88         }
  89
  90         public class Yield : YieldStatement<Iterator>
  91         {
  92                 public Yield (Expression expr, Location loc)
  93                         : base (expr, loc)
  94                 {
  95                 }
  96
  97                 public static bool CheckContext (BlockContext bc, Location loc)
  98                 {
  99                         if (!bc.CurrentAnonymousMethod.IsIterator) {
 100                                 bc.Report.Error (1621, loc,
 101                                         "The yield statement cannot be used inside anonymous method blocks");
 102                                 return false;
 103                         }
 104
 105                         if (bc.HasSet (ResolveContext.Options.FinallyScope)) {
 106                                 bc.Report.Error (1625, loc, "Cannot yield in the body of a finally clause");
 107                                 return false;
 108                         }
 109
 110                         return true;
 111                 }
 112
 113                 public override bool Resolve (BlockContext bc)
 114                 {
 115                         if (!CheckContext (bc, loc))
 116                                 return false;
 117
 118                         if (bc.HasAny (ResolveContext.Options.TryWithCatchScope)) {
 119                                 bc.Report.Error (1626, loc, "Cannot yield a value in the body of a try block with a catch clause");
 120                         }
 121
 122                         if (bc.HasSet (ResolveContext.Options.CatchScope)) {
 123                                 bc.Report.Error (1631, loc, "Cannot yield a value in the body of a catch clause");
 124                         }
 125
 126                         if (!base.Resolve (bc))
 127                                 return false;
 128
 129                         var otype = bc.CurrentIterator.OriginalIteratorType;
 130                         if (expr.Type != otype) {
 131                                 expr = Convert.ImplicitConversionRequired (bc, expr, otype, loc);
 132                                 if (expr == null)
 133                                         return false;
 134                         }
 135
 136                         return true;
 137                 }
 138
 139                 public override object Accept (StructuralVisitor visitor)
 140                 {
 141                         return visitor.Visit (this);
 142                 }
 143         }
 144
 145         public class YieldBreak : ExitStatement
 146         {
 147                 Iterator iterator;
 148
 149                 public YieldBreak (Location l)
 150                 {
 151                         loc = l;
 152                 }
 153
 154                 protected override bool IsLocalExit {
 155                         get {
 156                                 return false;
 157                         }
 158                 }
 159
 160                 protected override void CloneTo (CloneContext clonectx, Statement target)
 161                 {
 162                         throw new NotSupportedException ();
 163                 }
 164
 165                 protected override bool DoResolve (BlockContext bc)
 166                 {
 167                         iterator = bc.CurrentIterator;
 168                         return Yield.CheckContext (bc, loc);
 169                 }
 170
 171                 protected override void DoEmit (EmitContext ec)
 172                 {
 173                         iterator.EmitYieldBreak (ec, unwind_protect);
 174                 }
 175
 176                 protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
 177                 {
 178                         return true;
 179                 }
 180
 181                 public override Reachability MarkReachable (Reachability rc)
 182                 {
 183                         base.MarkReachable (rc);
 184                         return Reachability.CreateUnreachable ();
 185                 }
 186
 187                 public override object Accept (StructuralVisitor visitor)
 188                 {
 189                         return visitor.Visit (this);
 190                 }
 191         }
 192
 193         public abstract class StateMachine : AnonymousMethodStorey
 194         {
 195                 public enum State
 196                 {
 197                         Running = -3, // Used only in CurrentPC, never stored into $PC
 198                         Uninitialized = -2,
 199                         After = -1,
 200                         Start = 0
 201                 }
 202
 203                 Field pc_field;
 204                 StateMachineMethod method;
 205
 206                 protected StateMachine (ParametersBlock block, TypeDefinition parent, MemberBase host, TypeParameters tparams, string name, MemberKind kind)
 207                         : base (block, parent, host, tparams, name, kind)
 208                 {
 209                         OriginalTypeParameters = tparams;
 210                 }
 211
 212                 #region Properties
 213
 214                 public TypeParameters OriginalTypeParameters { get; private set; }
 215
 216                 public StateMachineMethod StateMachineMethod {
 217                         get {
 218                                 return method;
 219                         }
 220                 }
 221
 222                 public Field PC {
 223                         get {
 224                                 return pc_field;
 225                         }
 226                 }
 227
 228                 #endregion
 229
 230                 public void AddEntryMethod (StateMachineMethod method)
 231                 {
 232                         if (this.method != null)
 233                                 throw new InternalErrorException ();
 234
 235                         this.method = method;
 236                         Members.Add (method);
 237                 }
 238
 239                 protected override bool DoDefineMembers ()
 240                 {
 241                         pc_field = AddCompilerGeneratedField ("$PC", new TypeExpression (Compiler.BuiltinTypes.Int, Location));
 242
 243                         return base.DoDefineMembers ();
 244                 }
 245
 246                 protected override string GetVariableMangledName (ResolveContext rc, LocalVariable local_info)
 247                 {
 248                         if (local_info.IsCompilerGenerated)
 249                                 return base.GetVariableMangledName (rc, local_info);
 250
 251                         //
 252                         // Special format which encodes original variable name and
 253                         // it's scope to support lifted variables debugging. This
 254                         // is same what csc does and allows to correctly set fields
 255                         // scope information (like ambiguity, our of scope, etc).
 256                         //
 257                         var id = rc.CurrentBlock.Explicit.GetDebugSymbolScopeIndex ();
 258                         return "<" + local_info.Name + ">__" + id;
 259                 }
 260         }
 261
 262         class IteratorStorey : StateMachine
 263         {
 264                 class GetEnumeratorMethod : StateMachineMethod
 265                 {
 266                         sealed class GetEnumeratorStatement : Statement
 267                         {
 268                                 readonly IteratorStorey host;
 269                                 readonly StateMachineMethod host_method;
 270
 271                                 Expression new_storey;
 272
 273                                 public GetEnumeratorStatement (IteratorStorey host, StateMachineMethod host_method)
 274                                 {
 275                                         this.host = host;
 276                                         this.host_method = host_method;
 277                                         loc = host_method.Location;
 278                                 }
 279
 280                                 protected override void CloneTo (CloneContext clonectx, Statement target)
 281                                 {
 282                                         throw new NotSupportedException ();
 283                                 }
 284
 285                                 public override bool Resolve (BlockContext ec)
 286                                 {
 287                                         TypeExpression storey_type_expr = new TypeExpression (host.Definition, loc);
 288                                         List<Expression> init = null;
 289                                         if (host.hoisted_this != null) {
 290                                                 init = new List<Expression> (host.hoisted_params == null ? 1 : host.HoistedParameters.Count + 1);
 291                                                 HoistedThis ht = host.hoisted_this;
 292                                                 FieldExpr from = new FieldExpr (ht.Field, loc);
 293                                                 from.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, loc);
 294                                                 init.Add (new ElementInitializer (ht.Field.Name, from, loc));
 295                                         }
 296
 297                                         if (host.hoisted_params != null) {
 298                                                 if (init == null)
 299                                                         init = new List<Expression> (host.HoistedParameters.Count);
 300
 301                                                 for (int i = 0; i < host.hoisted_params.Count; ++i) {
 302                                                         HoistedParameter hp = host.hoisted_params [i];
 303                                                         HoistedParameter hp_cp = host.hoisted_params_copy [i] ?? hp;
 304
 305                                                         FieldExpr from = new FieldExpr (hp_cp.Field, loc);
 306                                                         from.InstanceExpression = new CompilerGeneratedThis (ec.CurrentType, loc);
 307
 308                                                         init.Add (new ElementInitializer (hp.Field.Name, from, loc));
 309                                                 }
 310                                         }
 311
 312                                         if (init != null) {
 313                                                 new_storey = new NewInitialize (storey_type_expr, null,
 314                                                         new CollectionOrObjectInitializers (init, loc), loc);
 315                                         } else {
 316                                                 new_storey = new New (storey_type_expr, null, loc);
 317                                         }
 318
 319                                         new_storey = new_storey.Resolve (ec);
 320                                         if (new_storey != null)
 321                                                 new_storey = Convert.ImplicitConversionRequired (ec, new_storey, host_method.MemberType, loc);
 322
 323                                         return true;
 324                                 }
 325
 326                                 protected override void DoEmit (EmitContext ec)
 327                                 {
 328                                         Label label_init = ec.DefineLabel ();
 329
 330                                         ec.EmitThis ();
 331                                         ec.Emit (OpCodes.Ldflda, host.PC.Spec);
 332                                         ec.EmitInt ((int) State.Start);
 333                                         ec.EmitInt ((int) State.Uninitialized);
 334
 335                                         var m = ec.Module.PredefinedMembers.InterlockedCompareExchange.Resolve (loc);
 336                                         if (m != null)
 337                                                 ec.Emit (OpCodes.Call, m);
 338
 339                                         ec.EmitInt ((int) State.Uninitialized);
 340                                         ec.Emit (OpCodes.Bne_Un_S, label_init);
 341
 342                                         ec.EmitThis ();
 343                                         ec.Emit (OpCodes.Ret);
 344
 345                                         ec.MarkLabel (label_init);
 346
 347                                         new_storey.Emit (ec);
 348                                         ec.Emit (OpCodes.Ret);
 349                                 }
 350
 351                                 protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
 352                                 {
 353                                         throw new NotImplementedException ();
 354                                 }
 355
 356                                 public override Reachability MarkReachable (Reachability rc)
 357                                 {
 358                                         base.MarkReachable (rc);
 359                                         return Reachability.CreateUnreachable ();
 360                                 }
 361                         }
 362
 363                         GetEnumeratorMethod (IteratorStorey host, FullNamedExpression returnType, MemberName name)
 364                                 : base (host, null, returnType, Modifiers.DEBUGGER_HIDDEN, name, ToplevelBlock.Flags.CompilerGenerated | ToplevelBlock.Flags.NoFlowAnalysis)
 365                         {
 366                         }
 367
 368                         public static GetEnumeratorMethod Create (IteratorStorey host, FullNamedExpression returnType, MemberName name)
 369                         {
 370                                 return Create (host, returnType, name, null);
 371                         }
 372
 373                         public static GetEnumeratorMethod Create (IteratorStorey host, FullNamedExpression returnType, MemberName name, Statement statement)
 374                         {
 375                                 var m = new GetEnumeratorMethod (host, returnType, name);
 376                                 var stmt = statement ?? new GetEnumeratorStatement (host, m);
 377                                 m.block.AddStatement (stmt);
 378                                 return m;
 379                         }
 380                 }
 381
 382                 class DisposeMethod : StateMachineMethod
 383                 {
 384                         sealed class DisposeMethodStatement : Statement
 385                         {
 386                                 Iterator iterator;
 387
 388                                 public DisposeMethodStatement (Iterator iterator)
 389                                 {
 390                                         this.iterator = iterator;
 391                                         this.loc = iterator.Location;
 392                                 }
 393
 394                                 protected override void CloneTo (CloneContext clonectx, Statement target)
 395                                 {
 396                                         throw new NotSupportedException ();
 397                                 }
 398
 399                                 public override bool Resolve (BlockContext ec)
 400                                 {
 401                                         return true;
 402                                 }
 403
 404                                 protected override void DoEmit (EmitContext ec)
 405                                 {
 406                                         ec.CurrentAnonymousMethod = iterator;
 407                                         iterator.EmitDispose (ec);
 408                                 }
 409
 410                                 protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
 411                                 {
 412                                         throw new NotImplementedException ();
 413                                 }
 414                         }
 415
 416                         public DisposeMethod (IteratorStorey host)
 417                                 : base (host, null, new TypeExpression (host.Compiler.BuiltinTypes.Void, host.Location), Modifiers.PUBLIC | Modifiers.DEBUGGER_HIDDEN,
 418                                         new MemberName ("Dispose", host.Location), ToplevelBlock.Flags.CompilerGenerated | ToplevelBlock.Flags.NoFlowAnalysis)
 419                         {
 420                                 host.Members.Add (this);
 421
 422                                 Block.AddStatement (new DisposeMethodStatement (host.Iterator));
 423                         }
 424                 }
 425
 426                 //
 427                 // Uses Method as method info
 428                 //
 429                 class DynamicMethodGroupExpr : MethodGroupExpr
 430                 {
 431                         readonly Method method;
 432
 433                         public DynamicMethodGroupExpr (Method method, Location loc)
 434                                 : base ((IList<MemberSpec>) null, null, loc)
 435                         {
 436                                 this.method = method;
 437                                 eclass = ExprClass.Unresolved;
 438                         }
 439
 440                         protected override Expression DoResolve (ResolveContext ec)
 441                         {
 442                                 Methods = new List<MemberSpec> (1) { method.Spec };
 443                                 type = method.Parent.Definition;
 444                                 InstanceExpression = new CompilerGeneratedThis (type, Location);
 445                                 return base.DoResolve (ec);
 446                         }
 447                 }
 448
 449                 class DynamicFieldExpr : FieldExpr
 450                 {
 451                         readonly Field field;
 452
 453                         public DynamicFieldExpr (Field field, Location loc)
 454                                 : base (loc)
 455                         {
 456                                 this.field = field;
 457                         }
 458
 459                         protected override Expression DoResolve (ResolveContext ec)
 460                         {
 461                                 spec = field.Spec;
 462                                 type = spec.MemberType;
 463                                 InstanceExpression = new CompilerGeneratedThis (type, Location);
 464                                 return base.DoResolve (ec);
 465                         }
 466                 }
 467
 468                 public readonly Iterator Iterator;
 469
 470                 List<HoistedParameter> hoisted_params_copy;
 471
 472                 TypeExpr iterator_type_expr;
 473                 Field current_field;
 474                 Field disposing_field;
 475
 476                 TypeSpec generic_enumerator_type;
 477                 TypeSpec generic_enumerable_type;
 478
 479                 public IteratorStorey (Iterator iterator)
 480                         : base (iterator.Container.ParametersBlock, iterator.Host,
 481                           iterator.OriginalMethod as MemberBase, iterator.OriginalMethod.CurrentTypeParameters, "Iterator", MemberKind.Class)
 482                 {
 483                         this.Iterator = iterator;
 484                 }
 485
 486                 public Field CurrentField {
 487                         get {
 488                                 return current_field;
 489                         }
 490                 }
 491
 492                 public Field DisposingField {
 493                         get {
 494                                 return disposing_field;
 495                         }
 496                 }
 497
 498                 public IList<HoistedParameter> HoistedParameters {
 499                         get { return hoisted_params; }
 500                 }
 501
 502                 protected override Constructor DefineDefaultConstructor (bool is_static)
 503                 {
 504                         var ctor = base.DefineDefaultConstructor (is_static);
 505                         ctor.ModFlags |= Modifiers.DEBUGGER_HIDDEN;
 506                         return ctor;
 507                 }
 508
 509                 protected override TypeSpec[] ResolveBaseTypes (out FullNamedExpression base_class)
 510                 {
 511                         var mtype = Iterator.OriginalIteratorType;
 512                         if (Mutator != null)
 513                                 mtype = Mutator.Mutate (mtype);
 514
 515                         iterator_type_expr = new TypeExpression (mtype, Location);
 516
 517                         var ifaces = new List<TypeSpec> (5);
 518                         if (Iterator.IsEnumerable) {
 519                                 ifaces.Add (Compiler.BuiltinTypes.IEnumerable);
 520
 521                                 if (Module.PredefinedTypes.IEnumerableGeneric.Define ()) {
 522                                         generic_enumerable_type = Module.PredefinedTypes.IEnumerableGeneric.TypeSpec.MakeGenericType (Module, new[] { mtype });
 523                                         ifaces.Add (generic_enumerable_type);
 524                                 }
 525                         }
 526
 527                         ifaces.Add (Compiler.BuiltinTypes.IEnumerator);
 528                         ifaces.Add (Compiler.BuiltinTypes.IDisposable);
 529
 530                         var ienumerator_generic = Module.PredefinedTypes.IEnumeratorGeneric;
 531                         if (ienumerator_generic.Define ()) {
 532                                 generic_enumerator_type = ienumerator_generic.TypeSpec.MakeGenericType (Module, new [] { mtype });
 533                                 ifaces.Add (generic_enumerator_type);
 534                         }
 535
 536                         base_class = null;
 537
 538                         base_type = Compiler.BuiltinTypes.Object;
 539                         return ifaces.ToArray ();
 540                 }
 541
 542                 protected override bool DoDefineMembers ()
 543                 {
 544                         current_field = AddCompilerGeneratedField ("$current", iterator_type_expr);
 545                         disposing_field = AddCompilerGeneratedField ("$disposing", new TypeExpression (Compiler.BuiltinTypes.Bool, Location));
 546
 547                         if (Iterator.IsEnumerable && hoisted_params != null) {
 548                                 //
 549                                 // Iterators are independent, each GetEnumerator call has to
 550                                 // create same enumerator therefore we have to keep original values
 551                                 // around for re-initialization
 552                                 //
 553                                 hoisted_params_copy = new List<HoistedParameter> (hoisted_params.Count);
 554                                 foreach (HoistedParameter hp in hoisted_params) {
 555
 556                                         //
 557                                         // Don't create field copy for unmodified captured parameters
 558                                         //
 559                                         HoistedParameter hp_copy;
 560                                         if (hp.IsAssigned) {
 561                                                 hp_copy = new HoistedParameter (hp, "<$>" + hp.Field.Name);
 562                                         } else {
 563                                                 hp_copy = null;
 564                                         }
 565
 566                                         hoisted_params_copy.Add (hp_copy);
 567                                 }
 568                         }
 569
 570                         if (generic_enumerator_type != null)
 571                                 Define_Current (true);
 572
 573                         Define_Current (false);
 574                         new DisposeMethod (this);
 575                         Define_Reset ();
 576
 577                         if (Iterator.IsEnumerable) {
 578                                 FullNamedExpression explicit_iface = new TypeExpression (Compiler.BuiltinTypes.IEnumerable, Location);
 579                                 var name = new MemberName ("GetEnumerator", null, explicit_iface, Location.Null);
 580
 581                                 if (generic_enumerator_type != null) {
 582                                         explicit_iface = new TypeExpression (generic_enumerable_type, Location);
 583                                         var gname = new MemberName ("GetEnumerator", null, explicit_iface, Location.Null);
 584                                         Method gget_enumerator = GetEnumeratorMethod.Create (this, new TypeExpression (generic_enumerator_type, Location), gname);
 585
 586                                         //
 587                                         // Just call generic GetEnumerator implementation
 588                                         //
 589                                         var stmt = new Return (new Invocation (new DynamicMethodGroupExpr (gget_enumerator, Location), null), Location);
 590                                         Method get_enumerator = GetEnumeratorMethod.Create (this, new TypeExpression (Compiler.BuiltinTypes.IEnumerator, Location), name, stmt);
 591
 592                                         Members.Add (get_enumerator);
 593                                         Members.Add (gget_enumerator);
 594                                 } else {
 595                                         Members.Add (GetEnumeratorMethod.Create (this, new TypeExpression (Compiler.BuiltinTypes.IEnumerator, Location), name));
 596                                 }
 597                         }
 598
 599                         return base.DoDefineMembers ();
 600                 }
 601
 602                 void Define_Current (bool is_generic)
 603                 {
 604                         TypeExpr type;
 605                         FullNamedExpression explicit_iface;
 606
 607                         if (is_generic) {
 608                                 explicit_iface = new TypeExpression (generic_enumerator_type, Location);
 609                                 type = iterator_type_expr;
 610                         } else {
 611                                 explicit_iface = new TypeExpression (Module.Compiler.BuiltinTypes.IEnumerator, Location);
 612                                 type = new TypeExpression (Compiler.BuiltinTypes.Object, Location);
 613                         }
 614
 615                         var name = new MemberName ("Current", null, explicit_iface, Location);
 616
 617                         ToplevelBlock get_block = new ToplevelBlock (Compiler, ParametersCompiled.EmptyReadOnlyParameters, Location,
 618                                 Block.Flags.CompilerGenerated | Block.Flags.NoFlowAnalysis);
 619                         get_block.AddStatement (new Return (new DynamicFieldExpr (CurrentField, Location), Location));
 620
 621                         Property current = new Property (this, type, Modifiers.DEBUGGER_HIDDEN | Modifiers.COMPILER_GENERATED, name, null);
 622                         current.Get = new Property.GetMethod (current, Modifiers.COMPILER_GENERATED, null, Location);
 623                         current.Get.Block = get_block;
 624
 625                         Members.Add (current);
 626                 }
 627
 628                 void Define_Reset ()
 629                 {
 630                         Method reset = new Method (
 631                                 this, new TypeExpression (Compiler.BuiltinTypes.Void, Location),
 632                                 Modifiers.PUBLIC | Modifiers.DEBUGGER_HIDDEN | Modifiers.COMPILER_GENERATED,
 633                                 new MemberName ("Reset", Location),
 634                                 ParametersCompiled.EmptyReadOnlyParameters, null);
 635                         Members.Add (reset);
 636
 637                         reset.Block = new ToplevelBlock (Compiler, reset.ParameterInfo, Location,
 638                                 Block.Flags.CompilerGenerated | Block.Flags.NoFlowAnalysis);
 639
 640                         TypeSpec ex_type = Module.PredefinedTypes.NotSupportedException.Resolve ();
 641                         if (ex_type == null)
 642                                 return;
 643
 644                         reset.Block.AddStatement (new Throw (new New (new TypeExpression (ex_type, Location), null, Location), Location));
 645                 }
 646
 647                 protected override void EmitHoistedParameters (EmitContext ec, List<HoistedParameter> hoisted)
 648                 {
 649                         base.EmitHoistedParameters (ec, hoisted);
 650                         if (hoisted_params_copy != null)
 651                                 base.EmitHoistedParameters (ec, hoisted_params_copy);
 652                 }
 653         }
 654
 655         public class StateMachineMethod : Method
 656         {
 657                 readonly StateMachineInitializer expr;
 658
 659                 public StateMachineMethod (StateMachine host, StateMachineInitializer expr, FullNamedExpression returnType,
 660                         Modifiers mod, MemberName name, ToplevelBlock.Flags blockFlags)
 661                         : base (host, returnType, mod | Modifiers.COMPILER_GENERATED,
 662                           name, ParametersCompiled.EmptyReadOnlyParameters, null)
 663                 {
 664                         this.expr = expr;
 665                         Block = new ToplevelBlock (host.Compiler, ParametersCompiled.EmptyReadOnlyParameters, Location.Null, blockFlags);
 666                 }
 667
 668                 public override EmitContext CreateEmitContext (ILGenerator ig, SourceMethodBuilder sourceMethod)
 669                 {
 670                         EmitContext ec = new EmitContext (this, ig, MemberType, sourceMethod);
 671                         ec.CurrentAnonymousMethod = expr;
 672
 673                         if (expr is AsyncInitializer)
 674                                 ec.With (BuilderContext.Options.AsyncBody, true);
 675
 676                         return ec;
 677                 }
 678         }
 679
 680         public abstract class StateMachineInitializer : AnonymousExpression
 681         {
 682                 sealed class MoveNextBodyStatement : Statement
 683                 {
 684                         readonly StateMachineInitializer state_machine;
 685
 686                         public MoveNextBodyStatement (StateMachineInitializer stateMachine)
 687                         {
 688                                 this.state_machine = stateMachine;
 689                                 this.loc = stateMachine.Location;
 690                         }
 691
 692                         protected override void CloneTo (CloneContext clonectx, Statement target)
 693                         {
 694                                 throw new NotSupportedException ();
 695                         }
 696
 697                         public override bool Resolve (BlockContext ec)
 698                         {
 699                                 return true;
 700                         }
 701
 702                         protected override void DoEmit (EmitContext ec)
 703                         {
 704                                 state_machine.EmitMoveNext (ec);
 705                         }
 706
 707                         public override void Emit (EmitContext ec)
 708                         {
 709                                 // Don't create sequence point
 710                                 DoEmit (ec);
 711                         }
 712
 713                         protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
 714                         {
 715                                 return state_machine.ReturnType.Kind != MemberKind.Void;
 716                         }
 717
 718                         public override Reachability MarkReachable (Reachability rc)
 719                         {
 720                                 base.MarkReachable (rc);
 721
 722                                 if (state_machine.ReturnType.Kind != MemberKind.Void)
 723                                         rc = Reachability.CreateUnreachable ();
 724
 725                                 return rc;
 726                         }
 727                 }
 728
 729                 public readonly TypeDefinition Host;
 730                 protected StateMachine storey;
 731
 732                 //
 733                 // The state as we generate the machine
 734                 //
 735                 protected Label move_next_ok;
 736                 protected Label move_next_error;
 737                 LocalBuilder skip_finally;
 738                 protected LocalBuilder current_pc;
 739                 protected List<ResumableStatement> resume_points;
 740
 741                 protected StateMachineInitializer (ParametersBlock block, TypeDefinition host, TypeSpec returnType)
 742                         : base (block, returnType, block.StartLocation)
 743                 {
 744                         this.Host = host;
 745                 }
 746
 747                 #region Properties
 748
 749                 public Label BodyEnd { get; set; }
 750
 751                 public LocalBuilder CurrentPC
 752                 {
 753                         get {
 754                                 return current_pc;
 755                         }
 756                 }
 757
 758                 public LocalBuilder SkipFinally {
 759                         get {
 760                                 return skip_finally;
 761                         }
 762                 }
 763
 764                 public override AnonymousMethodStorey Storey {
 765                         get {
 766                                 return storey;
 767                         }
 768                 }
 769
 770                 #endregion
 771
 772                 public int AddResumePoint (ResumableStatement stmt)
 773                 {
 774                         if (resume_points == null)
 775                                 resume_points = new List<ResumableStatement> ();
 776
 777                         resume_points.Add (stmt);
 778                         return resume_points.Count;
 779                 }
 780
 781                 public override Expression CreateExpressionTree (ResolveContext ec)
 782                 {
 783                         throw new NotSupportedException ("ET");
 784                 }
 785
 786                 protected virtual BlockContext CreateBlockContext (BlockContext bc)
 787                 {
 788                         var ctx = new BlockContext (bc, block, bc.ReturnType);
 789                         ctx.CurrentAnonymousMethod = this;
 790
 791                         ctx.AssignmentInfoOffset = bc.AssignmentInfoOffset;
 792                         ctx.EnclosingLoop = bc.EnclosingLoop;
 793                         ctx.EnclosingLoopOrSwitch = bc.EnclosingLoopOrSwitch;
 794                         ctx.Switch = bc.Switch;
 795
 796                         return ctx;
 797                 }
 798
 799                 protected override Expression DoResolve (ResolveContext rc)
 800                 {
 801                         var bc = (BlockContext) rc;
 802                         var ctx = CreateBlockContext (bc);
 803
 804                         Block.Resolve (ctx);
 805
 806                         if (!rc.IsInProbingMode) {
 807                                 var move_next = new StateMachineMethod (storey, this, new TypeExpression (ReturnType, loc), Modifiers.PUBLIC, new MemberName ("MoveNext", loc), 0);
 808                                 move_next.Block.AddStatement (new MoveNextBodyStatement (this));
 809                                 storey.AddEntryMethod (move_next);
 810                         }
 811
 812                         bc.AssignmentInfoOffset = ctx.AssignmentInfoOffset;
 813                         eclass = ExprClass.Value;
 814                         return this;
 815                 }
 816
 817                 public override void Emit (EmitContext ec)
 818                 {
 819                         //
 820                         // Load state machine instance
 821                         //
 822                         storey.Instance.Emit (ec);
 823                 }
 824
 825                 void EmitMoveNext_NoResumePoints (EmitContext ec)
 826                 {
 827                         ec.EmitThis ();
 828                         ec.Emit (OpCodes.Ldfld, storey.PC.Spec);
 829
 830                         ec.EmitThis ();
 831                         ec.EmitInt ((int) IteratorStorey.State.After);
 832                         ec.Emit (OpCodes.Stfld, storey.PC.Spec);
 833
 834                         // We only care if the PC is zero (start executing) or non-zero (don't do anything)
 835                         ec.Emit (OpCodes.Brtrue, move_next_error);
 836
 837                         BodyEnd = ec.DefineLabel ();
 838
 839                         var async_init = this as AsyncInitializer;
 840                         if (async_init != null)
 841                                 ec.BeginExceptionBlock ();
 842
 843                         block.EmitEmbedded (ec);
 844
 845                         if (async_init != null)
 846                                 async_init.EmitCatchBlock (ec);
 847
 848                         ec.MarkLabel (BodyEnd);
 849
 850                         EmitMoveNextEpilogue (ec);
 851
 852                         ec.MarkLabel (move_next_error);
 853
 854                         if (ReturnType.Kind != MemberKind.Void) {
 855                                 ec.EmitInt (0);
 856                                 ec.Emit (OpCodes.Ret);
 857                         }
 858
 859                         ec.MarkLabel (move_next_ok);
 860                 }
 861
 862                 void EmitMoveNext (EmitContext ec)
 863                 {
 864                         move_next_ok = ec.DefineLabel ();
 865                         move_next_error = ec.DefineLabel ();
 866
 867                         if (resume_points == null) {
 868                                 EmitMoveNext_NoResumePoints (ec);
 869                                 return;
 870                         }
 871
 872                         current_pc = ec.GetTemporaryLocal (ec.BuiltinTypes.UInt);
 873                         ec.EmitThis ();
 874                         ec.Emit (OpCodes.Ldfld, storey.PC.Spec);
 875                         ec.Emit (OpCodes.Stloc, current_pc);
 876
 877                         // We're actually in state 'running', but this is as good a PC value as any if there's an abnormal exit
 878                         ec.EmitThis ();
 879                         ec.EmitInt ((int) IteratorStorey.State.After);
 880                         ec.Emit (OpCodes.Stfld, storey.PC.Spec);
 881
 882                         Label[] labels = new Label[1 + resume_points.Count];
 883                         labels[0] = ec.DefineLabel ();
 884
 885                         bool need_skip_finally = false;
 886                         for (int i = 0; i < resume_points.Count; ++i) {
 887                                 ResumableStatement s = resume_points[i];
 888                                 need_skip_finally |= s is ExceptionStatement;
 889                                 labels[i + 1] = s.PrepareForEmit (ec);
 890                         }
 891
 892                         if (need_skip_finally) {
 893                                 skip_finally = ec.GetTemporaryLocal (ec.BuiltinTypes.Bool);
 894                                 ec.EmitInt (0);
 895                                 ec.Emit (OpCodes.Stloc, skip_finally);
 896                         }
 897
 898                         var async_init = this as AsyncInitializer;
 899                         if (async_init != null)
 900                                 ec.BeginExceptionBlock ();
 901
 902                         ec.Emit (OpCodes.Ldloc, current_pc);
 903                         ec.Emit (OpCodes.Switch, labels);
 904
 905                         ec.Emit (async_init != null ? OpCodes.Leave : OpCodes.Br, move_next_error);
 906
 907                         ec.MarkLabel (labels[0]);
 908
 909                         BodyEnd = ec.DefineLabel ();
 910
 911                         block.EmitEmbedded (ec);
 912
 913                         ec.MarkLabel (BodyEnd);
 914
 915                         if (async_init != null) {
 916                                 async_init.EmitCatchBlock (ec);
 917                         }
 918
 919                         ec.Mark (Block.Original.EndLocation);
 920                         ec.EmitThis ();
 921                         ec.EmitInt ((int) IteratorStorey.State.After);
 922                         ec.Emit (OpCodes.Stfld, storey.PC.Spec);
 923
 924                         EmitMoveNextEpilogue (ec);
 925
 926                         ec.MarkLabel (move_next_error);
 927
 928                         if (ReturnType.Kind != MemberKind.Void) {
 929                                 ec.EmitInt (0);
 930                                 ec.Emit (OpCodes.Ret);
 931                         }
 932
 933                         ec.MarkLabel (move_next_ok);
 934
 935                         if (ReturnType.Kind != MemberKind.Void) {
 936                                 ec.EmitInt (1);
 937                                 ec.Emit (OpCodes.Ret);
 938                         }
 939                 }
 940
 941                 protected virtual void EmitMoveNextEpilogue (EmitContext ec)
 942                 {
 943                 }
 944
 945                 public void EmitLeave (EmitContext ec, bool unwind_protect)
 946                 {
 947                         // Return ok
 948                         ec.Emit (unwind_protect ? OpCodes.Leave : OpCodes.Br, move_next_ok);
 949                 }
 950
 951                 //
 952                 // Called back from YieldStatement
 953                 //
 954                 public virtual void InjectYield (EmitContext ec, Expression expr, int resume_pc, bool unwind_protect, Label resume_point)
 955                 {
 956                         //
 957                         // Guard against being disposed meantime
 958                         //
 959                         Label disposed = ec.DefineLabel ();
 960                         var iterator = storey as IteratorStorey;
 961                         if (iterator != null) {
 962                                 ec.EmitThis ();
 963                                 ec.Emit (OpCodes.Ldfld, iterator.DisposingField.Spec);
 964                                 ec.Emit (OpCodes.Brtrue_S, disposed);
 965                         }
 966
 967                         //
 968                         // store resume program-counter
 969                         //
 970                         ec.EmitThis ();
 971                         ec.EmitInt (resume_pc);
 972                         ec.Emit (OpCodes.Stfld, storey.PC.Spec);
 973
 974                         if (iterator != null) {
 975                                 ec.MarkLabel (disposed);
 976                         }
 977
 978                         // mark finally blocks as disabled
 979                         if (unwind_protect && skip_finally != null) {
 980                                 ec.EmitInt (1);
 981                                 ec.Emit (OpCodes.Stloc, skip_finally);
 982                         }
 983                 }
 984
 985                 public void SetStateMachine (StateMachine stateMachine)
 986                 {
 987                         this.storey = stateMachine;
 988                 }
 989         }
 990
 991         //
 992         // Iterators are implemented as state machine blocks
 993         //
 994         public class Iterator : StateMachineInitializer
 995         {
 996                 sealed class TryFinallyBlockProxyStatement : Statement
 997                 {
 998                         TryFinallyBlock block;
 999                         Iterator iterator;
1000
1001                         public TryFinallyBlockProxyStatement (Iterator iterator, TryFinallyBlock block)
1002                         {
1003                                 this.iterator = iterator;
1004                                 this.block = block;
1005                         }
1006
1007                         protected override void CloneTo (CloneContext clonectx, Statement target)
1008                         {
1009                                 throw new NotSupportedException ();
1010                         }
1011
1012                         protected override bool DoFlowAnalysis (FlowAnalysisContext fc)
1013                         {
1014                                 throw new NotSupportedException ();
1015                         }
1016
1017                         protected override void DoEmit (EmitContext ec)
1018                         {
1019                                 //
1020                                 // Restore redirection for any captured variables
1021                                 //
1022                                 ec.CurrentAnonymousMethod = iterator;
1023
1024                                 using (ec.With (BuilderContext.Options.OmitDebugInfo, !ec.HasMethodSymbolBuilder)) {
1025                                         block.EmitFinallyBody (ec);
1026                                 }
1027                         }
1028                 }
1029
1030                 public readonly IMethodData OriginalMethod;
1031                 public readonly bool IsEnumerable;
1032                 public readonly TypeSpec OriginalIteratorType;
1033                 int finally_hosts_counter;
1034
1035                 public Iterator (ParametersBlock block, IMethodData method, TypeDefinition host, TypeSpec iterator_type, bool is_enumerable)
1036                         : base (block, host, host.Compiler.BuiltinTypes.Bool)
1037                 {
1038                         this.OriginalMethod = method;
1039                         this.OriginalIteratorType = iterator_type;
1040                         this.IsEnumerable = is_enumerable;
1041                         this.type = method.ReturnType;
1042                 }
1043
1044                 #region Properties
1045
1046                 public ToplevelBlock Container {
1047                         get { return OriginalMethod.Block; }
1048                 }
1049
1050                 public override string ContainerType {
1051                         get { return "iterator"; }
1052                 }
1053
1054                 public override bool IsIterator {
1055                         get { return true; }
1056                 }
1057
1058                 #endregion
1059
1060                 public Method CreateFinallyHost (TryFinallyBlock block)
1061                 {
1062                         var method = new Method (storey, new TypeExpression (storey.Compiler.BuiltinTypes.Void, loc),
1063                                 Modifiers.COMPILER_GENERATED, new MemberName (CompilerGeneratedContainer.MakeName (null, null, "Finally", finally_hosts_counter++), loc),
1064                                 ParametersCompiled.EmptyReadOnlyParameters, null);
1065
1066                         method.Block = new ToplevelBlock (method.Compiler, method.ParameterInfo, loc,
1067                                 ToplevelBlock.Flags.CompilerGenerated | ToplevelBlock.Flags.NoFlowAnalysis);
1068                         method.Block.AddStatement (new TryFinallyBlockProxyStatement (this, block));
1069
1070                         // Cannot it add to storey because it'd be emitted before nested
1071                         // anonoymous methods which could capture shared variable
1072
1073                         return method;
1074                 }
1075
1076                 public void EmitYieldBreak (EmitContext ec, bool unwind_protect)
1077                 {
1078                         ec.Emit (unwind_protect ? OpCodes.Leave : OpCodes.Br, move_next_error);
1079                 }
1080
1081                 public override string GetSignatureForError ()
1082                 {
1083                         return OriginalMethod.GetSignatureForError ();
1084                 }
1085
1086                 public override void Emit (EmitContext ec)
1087                 {
1088                         //
1089                         // Load Iterator storey instance
1090                         //
1091                         storey.Instance.Emit (ec);
1092
1093                         //
1094                         // Initialize iterator PC when it's unitialized
1095                         //
1096                         if (IsEnumerable) {
1097                                 ec.Emit (OpCodes.Dup);
1098                                 ec.EmitInt ((int)IteratorStorey.State.Uninitialized);
1099
1100                                 var field = storey.PC.Spec;
1101                                 if (storey.MemberName.IsGeneric) {
1102                                         field = MemberCache.GetMember (Storey.Instance.Type, field);
1103                                 }
1104
1105                                 ec.Emit (OpCodes.Stfld, field);
1106                         }
1107                 }
1108
1109                 public void EmitDispose (EmitContext ec)
1110                 {
1111                         if (resume_points == null)
1112                                 return;
1113
1114                         Label end = ec.DefineLabel ();
1115
1116                         Label[] labels = null;
1117                         for (int i = 0; i < resume_points.Count; ++i) {
1118                                 ResumableStatement s = resume_points[i];
1119                                 Label ret = s.PrepareForDispose (ec, end);
1120                                 if (ret.Equals (end) && labels == null)
1121                                         continue;
1122                                 if (labels == null) {
1123                                         labels = new Label[resume_points.Count + 1];
1124                                         for (int j = 0; j <= i; ++j)
1125                                                 labels[j] = end;
1126                                 }
1127
1128                                 labels[i + 1] = ret;
1129                         }
1130
1131                         if (labels != null) {
1132                                 current_pc = ec.GetTemporaryLocal (ec.BuiltinTypes.UInt);
1133                                 ec.EmitThis ();
1134                                 ec.Emit (OpCodes.Ldfld, storey.PC.Spec);
1135                                 ec.Emit (OpCodes.Stloc, current_pc);
1136                         }
1137
1138                         ec.EmitThis ();
1139                         ec.EmitInt (1);
1140                         ec.Emit (OpCodes.Stfld, ((IteratorStorey) storey).DisposingField.Spec);
1141
1142                         ec.EmitThis ();
1143                         ec.EmitInt ((int) IteratorStorey.State.After);
1144                         ec.Emit (OpCodes.Stfld, storey.PC.Spec);
1145
1146                         if (labels != null) {
1147                                 //SymbolWriter.StartIteratorDispatcher (ec.ig);
1148                                 ec.Emit (OpCodes.Ldloc, current_pc);
1149                                 ec.Emit (OpCodes.Switch, labels);
1150                                 //SymbolWriter.EndIteratorDispatcher (ec.ig);
1151
1152                                 foreach (ResumableStatement s in resume_points)
1153                                         s.EmitForDispose (ec, current_pc, end, true);
1154                         }
1155
1156                         ec.MarkLabel (end);
1157                 }
1158
1159                 public override void EmitStatement (EmitContext ec)
1160                 {
1161                         throw new NotImplementedException ();
1162                 }
1163
1164                 public override void InjectYield (EmitContext ec, Expression expr, int resume_pc, bool unwind_protect, Label resume_point)
1165                 {
1166                         // Store the new value into current
1167                         var fe = new FieldExpr (((IteratorStorey) storey).CurrentField, loc);
1168                         fe.InstanceExpression = new CompilerGeneratedThis (storey.CurrentType, loc);
1169                         fe.EmitAssign (ec, expr, false, false);
1170
1171                         base.InjectYield (ec, expr, resume_pc, unwind_protect, resume_point);
1172
1173                         EmitLeave (ec, unwind_protect);
1174
1175                         ec.MarkLabel (resume_point);
1176                 }
1177
1178                 public static void CreateIterator (IMethodData method, TypeDefinition parent, Modifiers modifiers)
1179                 {
1180                         bool is_enumerable;
1181                         TypeSpec iterator_type;
1182
1183                         TypeSpec ret = method.ReturnType;
1184                         if (ret == null)
1185                                 return;
1186
1187                         if (!CheckType (ret, parent, out iterator_type, out is_enumerable)) {
1188                                 parent.Compiler.Report.Error (1624, method.Location,
1189                                               "The body of `{0}' cannot be an iterator block " +
1190                                               "because `{1}' is not an iterator interface type",
1191                                               method.GetSignatureForError (),
1192                                               ret.GetSignatureForError ());
1193                                 return;
1194                         }
1195
1196                         ParametersCompiled parameters = method.ParameterInfo;
1197                         for (int i = 0; i < parameters.Count; i++) {
1198                                 Parameter p = parameters [i];
1199                                 Parameter.Modifier mod = p.ModFlags;
1200                                 if ((mod & Parameter.Modifier.RefOutMask) != 0) {
1201                                         parent.Compiler.Report.Error (1623, p.Location,
1202                                                 "Iterators cannot have ref or out parameters");
1203                                         return;
1204                                 }
1205
1206                                 if (p is ArglistParameter) {
1207                                         parent.Compiler.Report.Error (1636, method.Location,
1208                                                 "__arglist is not allowed in parameter list of iterators");
1209                                         return;
1210                                 }
1211
1212                                 if (parameters.Types [i].IsPointer) {
1213                                         parent.Compiler.Report.Error (1637, p.Location,
1214                                                 "Iterators cannot have unsafe parameters or yield types");
1215                                         return;
1216                                 }
1217                         }
1218
1219                         if ((modifiers & Modifiers.UNSAFE) != 0) {
1220                                 parent.Compiler.Report.Error (1629, method.Location, "Unsafe code may not appear in iterators");
1221                         }
1222
1223                         method.Block = method.Block.ConvertToIterator (method, parent, iterator_type, is_enumerable);
1224                 }
1225
1226                 static bool CheckType (TypeSpec ret, TypeContainer parent, out TypeSpec original_iterator_type, out bool is_enumerable)
1227                 {
1228                         original_iterator_type = null;
1229                         is_enumerable = false;
1230
1231                         if (ret.BuiltinType == BuiltinTypeSpec.Type.IEnumerable) {
1232                                 original_iterator_type = parent.Compiler.BuiltinTypes.Object;
1233                                 is_enumerable = true;
1234                                 return true;
1235                         }
1236                         if (ret.BuiltinType == BuiltinTypeSpec.Type.IEnumerator) {
1237                                 original_iterator_type = parent.Compiler.BuiltinTypes.Object;
1238                                 is_enumerable = false;
1239                                 return true;
1240                         }
1241
1242                         InflatedTypeSpec inflated = ret as InflatedTypeSpec;
1243                         if (inflated == null)
1244                                 return false;
1245
1246                         var member_definition = inflated.MemberDefinition;
1247                         PredefinedType ptype = parent.Module.PredefinedTypes.IEnumerableGeneric;
1248
1249                         if (ptype.Define () && ptype.TypeSpec.MemberDefinition == member_definition) {
1250                                 original_iterator_type = inflated.TypeArguments[0];
1251                                 is_enumerable = true;
1252                                 return true;
1253                         }
1254
1255                         ptype = parent.Module.PredefinedTypes.IEnumeratorGeneric;
1256                         if (ptype.Define () && ptype.TypeSpec.MemberDefinition == member_definition) {
1257                                 original_iterator_type = inflated.TypeArguments[0];
1258                                 is_enumerable = false;
1259                                 return true;
1260                         }
1261
1262                         return false;
1263                 }
1264         }
1265 }
1266