mcs/gmcs/anonymous.cs

   1 //
   2 // anonymous.cs: Support for anonymous methods
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximain.com)
   6 //
   7 // (C) 2003, 2004 Novell, Inc.
   8 //
   9 // TODO: Ideally, we should have the helper classes emited as a hierarchy to map
  10 // their nesting, and have the visibility set to private, instead of NestedAssembly
  11 //
  12 //
  13 //
  14
  15 using System;
  16 using System.Text;
  17 using System.Collections;
  18 using System.Reflection;
  19 using System.Reflection.Emit;
  20
  21 namespace Mono.CSharp {
  22
  23         public abstract class AnonymousContainer : Expression
  24         {
  25                 // Used to generate unique method names.
  26                 protected static int anonymous_method_count;
  27
  28                 // An array list of AnonymousMethodParameter or null
  29                 public Parameters Parameters;
  30
  31                 //
  32                 // The block that makes up the body for the anonymous mehtod
  33                 //
  34                 public ToplevelBlock Block;
  35
  36                 //
  37                 // The container block for this anonymous method.
  38                 //
  39                 public Block ContainingBlock;
  40
  41                 //
  42                 // The implicit method we create
  43                 //
  44                 public Method method;
  45
  46                 protected MethodInfo invoke_mb;
  47
  48                 // The emit context for the anonymous method
  49                 public EmitContext aec;
  50                 public Parameters amp;
  51                 public string[] TypeParameters;
  52                 public Type[] TypeArguments;
  53                 protected bool unreachable;
  54
  55                 //
  56                 // The modifiers applied to the method, we aggregate them
  57                 //
  58                 protected int method_modifiers = Modifiers.PRIVATE;
  59
  60                 //
  61                 // During the resolve stage of the anonymous method body,
  62                 // we discover the actual scope where we are hosted, or
  63                 // null to host the method in the same class
  64                 //
  65                 public ScopeInfo Scope;
  66
  67                 //
  68                 // Points to our container anonymous method if its present
  69                 //
  70                 public AnonymousContainer ContainerAnonymousMethod;
  71
  72                 protected AnonymousContainer (Parameters parameters, ToplevelBlock container,
  73                                               ToplevelBlock block, Location l)
  74                 {
  75                         Parameters = parameters;
  76                         Block = block;
  77                         loc = l;
  78
  79                         //
  80                         // The order is important: this setups the CaptureContext tree hierarchy.
  81                         //
  82                         if (container == null) {
  83                                 Report.Error (1706, l, "Anonymous methods are not allowed in attribute declaration");
  84                                 return;
  85                         }
  86                         container.SetHaveAnonymousMethods (l, this);
  87                         block.SetHaveAnonymousMethods (l, this);
  88                 }
  89
  90                 protected AnonymousContainer (Parameters parameters, ToplevelBlock container,
  91                                               Location l):
  92                         this (parameters, container, new ToplevelBlock (container, parameters, l), l)
  93                 {
  94                 }
  95
  96                 public override Expression DoResolve (EmitContext ec)
  97                 {
  98                         //
  99                         // Set class type, set type
 100                         //
 101
 102                         eclass = ExprClass.Value;
 103
 104                         //
 105                         // This hack means `The type is not accessible
 106                         // anywhere', we depend on special conversion
 107                         // rules.
 108                         //
 109                         type = TypeManager.anonymous_method_type;
 110
 111                         return this;
 112                 }
 113
 114                 protected abstract bool CreateMethodHost (EmitContext ec);
 115
 116                 public abstract void CreateScopeType (EmitContext ec, ScopeInfo scope);
 117
 118                 public abstract Iterator Iterator {
 119                         get;
 120                 }
 121
 122                 public abstract bool IsIterator {
 123                         get;
 124                 }
 125         }
 126
 127         public class AnonymousMethod : AnonymousContainer
 128         {
 129                 public AnonymousMethod (Parameters parameters, ToplevelBlock container,
 130                                         ToplevelBlock block, Location l)
 131                         : base (parameters, container, block, l)
 132                 {
 133                 }
 134
 135                 public override Iterator Iterator {
 136                         get { return null; }
 137                 }
 138
 139                 public override bool IsIterator {
 140                         get { return false; }
 141                 }
 142
 143                 public override void Emit (EmitContext ec)
 144                 {
 145                         // nothing, as we only exist to not do anything.
 146                 }
 147
 148                 //
 149                 // Creates the host for the anonymous method
 150                 //
 151                 protected override bool CreateMethodHost (EmitContext ec)
 152                 {
 153                         //
 154                         // Crude hack follows: we replace the TypeBuilder during the
 155                         // definition to get the method hosted in the right class
 156                         //
 157
 158                         TypeBuilder current_type = ec.TypeContainer.TypeBuilder;
 159                         TypeBuilder type_host = (Scope == null ) // || Scope.ScopeTypeBuilder == null)
 160                                 ? current_type : Scope.ScopeTypeBuilder;
 161
 162                         if (current_type == null)
 163                                 throw new Exception ("The current_type is null");
 164
 165                         if (type_host == null)
 166                                 throw new Exception (String.Format ("Type host is null, Scope is {0}", Scope == null ? "null" : "Not null"));
 167
 168                         if (current_type != type_host)
 169                                 method_modifiers = Modifiers.INTERNAL;
 170
 171                         if (current_type == type_host && ec.IsStatic){
 172                                 method_modifiers |= Modifiers.STATIC;
 173                                 current_type = null;
 174                         }
 175
 176                         string name = "<#AnonymousMethod>" + anonymous_method_count++;
 177                         MemberName member_name;
 178
 179                         GenericMethod generic_method = null;
 180                         if (TypeParameters != null) {
 181                                 TypeArguments args = new TypeArguments (loc);
 182                                 foreach (string t in TypeParameters)
 183                                         args.Add (new SimpleName (t, loc));
 184
 185                                 member_name = new MemberName (name, args, loc);
 186
 187                                 generic_method = new GenericMethod (
 188                                         ec.DeclSpace.NamespaceEntry,
 189                                         (TypeContainer) ec.TypeContainer, member_name,
 190                                         new TypeExpression (invoke_mb.ReturnType, loc),
 191                                         Parameters);
 192
 193                                 generic_method.SetParameterInfo (null);
 194                         } else
 195                                 member_name = new MemberName (name, loc);
 196
 197                         method = new Method (
 198                                 (TypeContainer) ec.TypeContainer, generic_method,
 199                                 new TypeExpression (invoke_mb.ReturnType, loc),
 200                                 method_modifiers, false, member_name, Parameters, null);
 201                         method.Block = Block;
 202
 203                         //
 204                         // Swap the TypeBuilder while we define the method, then restore
 205                         //
 206                         if (current_type != null)
 207                                 ec.TypeContainer.TypeBuilder = type_host;
 208                         bool res = method.Define ();
 209                         if (current_type != null)
 210                                 ec.TypeContainer.TypeBuilder = current_type;
 211
 212                         return res;
 213                 }
 214
 215                 void Error_ParameterMismatch (Type t)
 216                 {
 217                         Report.Error (1661, loc, "Anonymous method could not be converted to delegate `" +
 218                                       "{0}' since there is a parameter mismatch", TypeManager.CSharpName (t));
 219         }
 220
 221                 //
 222                 // Returns true if this anonymous method can be implicitly
 223                 // converted to the delegate type `delegate_type'
 224                 //
 225                 public Expression Compatible (EmitContext ec, Type delegate_type, bool probe)
 226                 {
 227                         //
 228                         // At this point its the first time we know the return type that is
 229                         // needed for the anonymous method.  We create the method here.
 230                         //
 231
 232                         MethodGroupExpr invoke_mg = Delegate.GetInvokeMethod (ec, delegate_type, loc);
 233                         invoke_mb = (MethodInfo) invoke_mg.Methods [0];
 234                         ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
 235
 236                         if (delegate_type.IsGenericType) {
 237                                 Type def = delegate_type.GetGenericTypeDefinition ();
 238
 239                                 if (def != delegate_type) {
 240                                         Type[] tparam = TypeManager.GetTypeArguments (def);
 241
 242                                         TypeArguments = TypeManager.GetTypeArguments (delegate_type);
 243                                         TypeParameters = new string [tparam.Length];
 244                                         for (int i = 0; i < tparam.Length; i++)
 245                                                 TypeParameters [i] = tparam [i].Name;
 246                                 }
 247                         }
 248
 249                         if (Parameters == null){
 250                                 //
 251                                 // We provide a set of inaccessible parameters
 252                                 //
 253                                 Parameter [] fixedpars = new Parameter [invoke_pd.Count];
 254
 255                                 for (int i = 0; i < invoke_pd.Count; i++){
 256                                         fixedpars [i] = new Parameter (
 257                                                 invoke_pd.ParameterType (i),
 258                                                 "+" + i, invoke_pd.ParameterModifier (i), null, loc);
 259                                 }
 260
 261                                 Parameters = new Parameters (fixedpars);
 262                         }
 263
 264                         //
 265                         // First, parameter types of `delegate_type' must be compatible
 266                         // with the anonymous method.
 267                         //
 268                         Parameters.Resolve (ec);
 269                         amp = Parameters;
 270
 271                         if (amp.Count != invoke_pd.Count){
 272                                 if (!probe){
 273                                         Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
 274                                                 TypeManager.CSharpName (delegate_type), amp.Count.ToString ());
 275                                         Error_ParameterMismatch (delegate_type);
 276                                 }
 277                                 return null;
 278                         }
 279
 280                         for (int i = 0; i < amp.Count; i++){
 281                                 Parameter.Modifier amp_mod = amp.ParameterModifier (i);
 282
 283                                 if (!probe) {
 284                                         if ((amp_mod & (Parameter.Modifier.OUT | Parameter.Modifier.REF)) != 0){
 285                                                 Report.Error (1677, loc, "Parameter `{0}' should not be declared with the `{1}' keyword",
 286                                                         (i+1).ToString (), Parameter.GetModifierSignature (amp_mod));
 287                                                 Error_ParameterMismatch (delegate_type);
 288                                                 return null;
 289                                         }
 290
 291                                         if (amp_mod != invoke_pd.ParameterModifier (i)){
 292                                                 Report.Error (1676, loc, "Parameter `{0}' must be declared with the `{1}' keyword",
 293                                                         (i+1).ToString (), Parameter.GetModifierSignature (invoke_pd.ParameterModifier (i)));
 294                                                 Error_ParameterMismatch (delegate_type);
 295                                                 return null;
 296                                         }
 297
 298                                         if (amp.ParameterType (i) != invoke_pd.ParameterType (i)){
 299                                                 Report.Error (1678, loc, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
 300                                                         (i+1).ToString (),
 301                                                         TypeManager.CSharpName (amp.ParameterType (i)),
 302                                                         TypeManager.CSharpName (invoke_pd.ParameterType (i)));
 303                                                 Error_ParameterMismatch (delegate_type);
 304                                                 return null;
 305                                         }
 306                                 }
 307                         }
 308
 309                         //
 310                         // If we are only probing, return ourselves
 311                         //
 312                         if (probe)
 313                                 return this;
 314
 315                         //
 316                         // Second: the return type of the delegate must be compatible with
 317                         // the anonymous type.   Instead of doing a pass to examine the block
 318                         // we satisfy the rule by setting the return type on the EmitContext
 319                         // to be the delegate type return type.
 320                         //
 321
 322                         //MethodBuilder builder = method_data.MethodBuilder;
 323                         //ILGenerator ig = builder.GetILGenerator ();
 324
 325
 326                         aec = new EmitContext (
 327                                 ec.TypeContainer, ec.DeclSpace, loc, null,
 328                                 invoke_mb.ReturnType,
 329                                 /* REVIEW */ (ec.InIterator ? Modifiers.METHOD_YIELDS : 0) |
 330                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0) |
 331                                 (ec.IsStatic ? Modifiers.STATIC : 0),
 332                                 /* No constructor */ false);
 333
 334                         aec.CurrentAnonymousMethod = this;
 335                         ContainerAnonymousMethod = ec.CurrentAnonymousMethod;
 336                         ContainingBlock = ec.CurrentBlock;
 337
 338                         if (aec.ResolveTopBlock (ec, Block, amp, null, out unreachable))
 339                                 return new AnonymousDelegate (this, delegate_type, loc).Resolve (ec);
 340
 341                         return null;
 342                 }
 343
 344                 public override string ExprClassName {
 345                         get {
 346                                 return "anonymous method";
 347                         }
 348                 }
 349
 350                 public MethodInfo GetMethodBuilder ()
 351                 {
 352                         MethodInfo builder = method.MethodData.MethodBuilder;
 353                         if (TypeArguments != null)
 354                                 return builder.MakeGenericMethod (TypeArguments);
 355                         else
 356                                 return builder;
 357                 }
 358
 359                 public override string GetSignatureForError ()
 360                 {
 361                         string s = TypeManager.CSharpSignature (invoke_mb);
 362                         return s.Substring (0, s.IndexOf (".Invoke("));
 363                 }
 364
 365                 public bool EmitMethod (EmitContext ec)
 366                 {
 367                         if (!CreateMethodHost (ec))
 368                                 return false;
 369
 370                         MethodBuilder builder = method.MethodData.MethodBuilder;
 371                         ILGenerator ig = builder.GetILGenerator ();
 372                         aec.ig = ig;
 373
 374                         Parameters.ApplyAttributes (aec, builder);
 375
 376                         //
 377                         // Adjust based on the computed state of the
 378                         // method from CreateMethodHost
 379
 380                         aec.MethodIsStatic = (method_modifiers & Modifiers.STATIC) != 0;
 381
 382                         aec.EmitMeta (Block);
 383                         aec.EmitResolvedTopBlock (Block, unreachable);
 384                         return true;
 385                 }
 386
 387                 public override void CreateScopeType (EmitContext ec, ScopeInfo scope)
 388                 {
 389                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 390                         string name = String.Format ("<>AnonHelp<{0}>", scope.id);
 391
 392                         scope.ScopeTypeBuilder = container.DefineNestedType (
 393                                 name, TypeAttributes.AutoLayout | TypeAttributes.Class |
 394                                 TypeAttributes.NestedAssembly, TypeManager.object_type, null);
 395
 396                         Type [] constructor_types = TypeManager.NoTypes;
 397                         ConstructorBuilder ctor = scope.ScopeTypeBuilder.DefineConstructor (
 398                                 MethodAttributes.Public | MethodAttributes.HideBySig |
 399                                 MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
 400                                 CallingConventions.HasThis, constructor_types);
 401                         TypeManager.RegisterMethod (ctor, Parameters.EmptyReadOnlyParameters);
 402
 403                         ILGenerator cig = ctor.GetILGenerator ();
 404                         cig.Emit (OpCodes.Ldarg_0);
 405                         cig.Emit (OpCodes.Call, TypeManager.object_ctor);
 406                         cig.Emit (OpCodes.Ret);
 407
 408                         if (ec.TypeContainer.IsGeneric) {
 409                                 TypeParameter[] tparam = ec.TypeContainer.TypeParameters;
 410                                 string[] names = new string [tparam.Length];
 411                                 Type[] types = new Type [tparam.Length];
 412
 413                                 for (int i = 0; i < names.Length; i++) {
 414                                         names [i] = tparam [i].Name;
 415                                         types [i] = tparam [i].Type;
 416                                 }
 417
 418                                 scope.ScopeTypeBuilder.DefineGenericParameters (names);
 419                                 scope.ScopeTypeBuilder.GetGenericTypeDefinition ();
 420
 421                                 scope.ScopeType = scope.ScopeTypeBuilder.MakeGenericType (types);
 422                         } else
 423                                 scope.ScopeType = scope.ScopeTypeBuilder;
 424
 425
 426                         if (ec.TypeContainer.IsGeneric)
 427                                 scope.ScopeConstructor = TypeBuilder.GetConstructor (
 428                                         scope.ScopeType, ctor);
 429                         else
 430                                 scope.ScopeConstructor = ctor;
 431                 }
 432
 433                 public static void Error_AddressOfCapturedVar (string name, Location loc)
 434                 {
 435                         Report.Error (1686, loc,
 436                                 "Local variable `{0}' or its members cannot have their address taken and be used inside an anonymous method block",
 437                                 name);
 438                 }
 439         }
 440
 441         //
 442         // This will emit the code for the delegate, as well delegate creation on the host
 443         //
 444         public class AnonymousDelegate : DelegateCreation {
 445                 AnonymousMethod am;
 446
 447                 public AnonymousDelegate (AnonymousMethod am, Type target_type, Location l)
 448                 {
 449                         type = target_type;
 450                         loc = l;
 451                         this.am = am;
 452                 }
 453
 454                 public override Expression DoResolve (EmitContext ec)
 455                 {
 456                         eclass = ExprClass.Value;
 457
 458                         return this;
 459                 }
 460
 461                 public override void Emit (EmitContext ec)
 462                 {
 463                         if (!am.EmitMethod (ec))
 464                                 return;
 465
 466                         //
 467                         // Now emit the delegate creation.
 468                         //
 469                         if ((am.method.ModFlags & Modifiers.STATIC) == 0)
 470                                 delegate_instance_expression = new AnonymousInstance (am);
 471
 472                         Expression ml = Expression.MemberLookup (ec, type, ".ctor", loc);
 473                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 474                         delegate_method = am.GetMethodBuilder ();
 475                         base.Emit (ec);
 476                 }
 477
 478                 class AnonymousInstance : Expression {
 479                         AnonymousMethod am;
 480
 481                         public AnonymousInstance (AnonymousMethod am)
 482                         {
 483                                 this.am = am;
 484                                 eclass = ExprClass.Value;
 485                         }
 486
 487                         public override Expression DoResolve (EmitContext ec)
 488                         {
 489                                 return this;
 490                         }
 491
 492                         public override void Emit (EmitContext ec)
 493                         {
 494                                 am.aec.EmitMethodHostInstance (ec, am);
 495                         }
 496                 }
 497         }
 498
 499         class CapturedParameter {
 500                 public Type Type;
 501                 public FieldBuilder FieldBuilder;
 502                 public int Idx;
 503
 504                 public CapturedParameter (Type type, int idx)
 505                 {
 506                         Type = type;
 507                         Idx = idx;
 508                 }
 509         }
 510
 511         //
 512         // Here we cluster all the variables captured on a given scope, we also
 513         // keep some extra information that might be required on each scope.
 514         //
 515         public class ScopeInfo {
 516                 public CaptureContext CaptureContext;
 517                 public ScopeInfo ParentScope;
 518                 public Block ScopeBlock;
 519                 public bool NeedThis = false;
 520                 public bool HostsParameters = false;
 521
 522                 // For tracking the number of scopes created.
 523                 public int id;
 524                 static int count;
 525                 bool inited = false;
 526
 527                 ArrayList locals = new ArrayList ();
 528                 ArrayList children = new ArrayList ();
 529
 530                 //
 531                 // The types and fields generated
 532                 //
 533                 public TypeBuilder ScopeTypeBuilder;
 534                 public Type ScopeType;
 535                 public ConstructorInfo ScopeConstructor;
 536                 public FieldBuilder THIS;
 537                 public FieldBuilder ParentLink;
 538
 539                 //
 540                 // Points to the object of type `ScopeTypeBuilder' that
 541                 // holds the data for the scope
 542                 //
 543                 LocalBuilder scope_instance;
 544
 545                 public ScopeInfo (CaptureContext cc, Block b)
 546                 {
 547                         CaptureContext = cc;
 548                         ScopeBlock = b;
 549                         id = count++;
 550
 551                         cc.AddScope (this);
 552                 }
 553
 554                 public void AddLocal (LocalInfo li)
 555                 {
 556                         if (locals.Contains (li))
 557                                 return;
 558
 559                         locals.Add (li);
 560 }
 561
 562                 public bool IsCaptured (LocalInfo li)
 563                 {
 564                         return locals.Contains (li);
 565                 }
 566
 567                 internal void AddChild (ScopeInfo si)
 568                 {
 569                         if (children.Contains (si))
 570                                 return;
 571
 572                         //
 573                         // If any of the current children should be a children of `si', move them there
 574                         //
 575                         ArrayList move_queue = null;
 576                         foreach (ScopeInfo child in children){
 577                                 if (child.ScopeBlock.IsChildOf (si.ScopeBlock)){
 578                                         if (move_queue == null)
 579                                                 move_queue = new ArrayList ();
 580                                         move_queue.Add (child);
 581                                         child.ParentScope = si;
 582                                         si.AddChild (child);
 583                                 }
 584                         }
 585
 586                         children.Add (si);
 587
 588                         if (move_queue != null){
 589                                 foreach (ScopeInfo child in move_queue){
 590                                         children.Remove (child);
 591                                 }
 592                         }
 593                 }
 594
 595                 static int indent = 0;
 596
 597                 void Pad ()
 598                 {
 599                         for (int i = 0; i < indent; i++)
 600                                 Console.Write ("    ");
 601                 }
 602
 603                 void EmitDebug ()
 604                 {
 605                         //Console.WriteLine (Environment.StackTrace);
 606                         Pad ();
 607                         Console.WriteLine ("START");
 608                         indent++;
 609                         Pad ();
 610                         Console.WriteLine ("NeedThis=" + NeedThis);
 611                         foreach (LocalInfo li in locals){
 612                                 Pad ();
 613                                 Console.WriteLine ("var {0}", MakeFieldName (li.Name));
 614                         }
 615
 616                         foreach (ScopeInfo si in children)
 617                                 si.EmitDebug ();
 618                         indent--;
 619                         Pad ();
 620                         Console.WriteLine ("END");
 621                 }
 622
 623                 public string MakeHelperName ()
 624                 {
 625                         return String.Format ("<>AnonHelp<{0}>", id);
 626                 }
 627
 628                 private string MakeFieldName (string local_name)
 629                 {
 630                         return "<" + id + ":" + local_name + ">";
 631                 }
 632
 633                 public void EmitScopeType (EmitContext ec)
 634                 {
 635                         // EmitDebug ();
 636
 637                         if (ScopeTypeBuilder != null)
 638                                 return;
 639
 640                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 641
 642                         CaptureContext.Host.CreateScopeType (ec, this);
 643
 644                         if (NeedThis)
 645                                 THIS = ScopeTypeBuilder.DefineField ("<>THIS", container, FieldAttributes.Assembly);
 646
 647                         if (ParentScope != null){
 648                                 if (ParentScope.ScopeTypeBuilder == null){
 649                                         throw new Exception (String.Format ("My parent has not been initialized {0} and {1}", ParentScope, this));
 650                                 }
 651
 652                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder)
 653                                         ParentLink = ScopeTypeBuilder.DefineField (
 654                                                 "<>parent", ParentScope.ScopeType, FieldAttributes.Assembly);
 655                         }
 656
 657                         if (NeedThis && ParentScope != null)
 658                                 throw new Exception ("I was not expecting THIS && having a parent");
 659
 660                         foreach (LocalInfo info in locals)
 661                                 info.FieldBuilder = ScopeTypeBuilder.DefineField (
 662                                         MakeFieldName (info.Name), info.VariableType, FieldAttributes.Assembly);
 663
 664                         if (HostsParameters){
 665                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 666
 667                                 foreach (DictionaryEntry de in captured_parameters){
 668                                         string name = (string) de.Key;
 669                                         CapturedParameter cp = (CapturedParameter) de.Value;
 670                                         FieldBuilder fb;
 671
 672                                         fb = ScopeTypeBuilder.DefineField ("<p:" + name + ">", cp.Type, FieldAttributes.Assembly);
 673                                         cp.FieldBuilder = fb;
 674                                 }
 675                         }
 676
 677                         foreach (ScopeInfo si in children){
 678                                 si.EmitScopeType (ec);
 679                         }
 680                 }
 681
 682                 public void CloseTypes ()
 683                 {
 684                         RootContext.RegisterCompilerGeneratedType (ScopeTypeBuilder);
 685                         foreach (ScopeInfo si in children)
 686                                 si.CloseTypes ();
 687                 }
 688
 689                 //
 690                 // Emits the initialization code for the scope
 691                 //
 692                 public void EmitInitScope (EmitContext ec)
 693                 {
 694                         ILGenerator ig = ec.ig;
 695
 696                         if (inited)
 697                                 return;
 698
 699                         if (ScopeConstructor == null)
 700                                 throw new Exception ("ScopeConstructor is null for" + this.ToString ());
 701
 702                         if (!CaptureContext.Host.IsIterator) {
 703                                 scope_instance = ig.DeclareLocal (ScopeType);
 704                                 ig.Emit (OpCodes.Newobj, ScopeConstructor);
 705                                 ig.Emit (OpCodes.Stloc, scope_instance);
 706                         }
 707
 708                         if (THIS != null){
 709                                 if (CaptureContext.Host.IsIterator) {
 710                                         ig.Emit (OpCodes.Ldarg_0);
 711                                         ig.Emit (OpCodes.Ldarg_1);
 712                                 } else {
 713                                         ig.Emit (OpCodes.Ldloc, scope_instance);
 714                                         ig.Emit (OpCodes.Ldarg_0);
 715                                 }
 716                                 ig.Emit (OpCodes.Stfld, THIS);
 717                         }
 718
 719                         //
 720                         // Copy the parameter values, if any
 721                         //
 722                         int extra = ec.IsStatic ? 0 : 1;
 723                         if (CaptureContext.Host.IsIterator)
 724                                 extra++;
 725                         if (HostsParameters){
 726                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 727
 728                                 foreach (DictionaryEntry de in captured_parameters){
 729                                         CapturedParameter cp = (CapturedParameter) de.Value;
 730
 731                                         EmitScopeInstance (ig);
 732                                         ParameterReference.EmitLdArg (ig, cp.Idx + extra);
 733                                         ig.Emit (OpCodes.Stfld, cp.FieldBuilder);
 734                                 }
 735                         }
 736
 737                         if (ParentScope != null){
 738                                 if (!ParentScope.inited)
 739                                         ParentScope.EmitInitScope (ec);
 740
 741                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder) {
 742                                         //
 743                                         // Only emit initialization in our capturecontext world
 744                                         //
 745                                         if (ParentScope.CaptureContext == CaptureContext){
 746                                                 EmitScopeInstance (ig);
 747                                                 ParentScope.EmitScopeInstance (ig);
 748                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 749                                         } else {
 750                                                 EmitScopeInstance (ig);
 751                                                 ig.Emit (OpCodes.Ldarg_0);
 752                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 753                                         }
 754                                 }
 755                         }
 756                         inited = true;
 757                 }
 758
 759                 public void EmitScopeInstance (ILGenerator ig)
 760                 {
 761                         if (CaptureContext.Host.IsIterator)
 762                                 ig.Emit (OpCodes.Ldarg_0);
 763                         else
 764                                 ig.Emit (OpCodes.Ldloc, scope_instance);
 765                 }
 766
 767                 public static void CheckCycles (string msg, ScopeInfo s)
 768                 {
 769                         ArrayList l = new ArrayList ();
 770                         int n = 0;
 771
 772                         for (ScopeInfo p = s; p != null; p = p.ParentScope,n++){
 773                                 if (l.Contains (p)){
 774                                         Console.WriteLine ("Loop detected {0} in {1}", n, msg);
 775                                         throw new Exception ();
 776                                 }
 777                                 l.Add (p);
 778                         }
 779                 }
 780
 781                 static void DoPath (StringBuilder sb, ScopeInfo start)
 782                 {
 783                         CheckCycles ("print", start);
 784
 785                         if (start.ParentScope != null){
 786                                 DoPath (sb, start.ParentScope);
 787                                 sb.Append (", ");
 788                         }
 789                         sb.Append ((start.id).ToString ());
 790                 }
 791
 792                 public override string ToString ()
 793                 {
 794                         StringBuilder sb = new StringBuilder ();
 795
 796                         sb.Append ("{");
 797                         if (CaptureContext != null){
 798                                 sb.Append (CaptureContext.ToString ());
 799                                 sb.Append (":");
 800                         }
 801
 802                         DoPath (sb, this);
 803                         sb.Append ("}");
 804
 805                         return sb.ToString ();
 806                 }
 807         }
 808
 809         //
 810         // CaptureContext objects are created on demand if a method has
 811         // anonymous methods and kept on the ToplevelBlock.
 812         //
 813         // If they exist, all ToplevelBlocks in the containing block are
 814         // linked together (children pointing to their parents).
 815         //
 816         public class CaptureContext {
 817                 public static int count;
 818                 public int cc_id;
 819                 public Location loc;
 820
 821                 //
 822                 // Points to the toplevel block that owns this CaptureContext
 823                 //
 824                 ToplevelBlock toplevel_owner;
 825                 Hashtable scopes = new Hashtable ();
 826                 bool have_captured_vars = false;
 827                 bool referenced_this = false;
 828                 ScopeInfo topmost = null;
 829
 830                 //
 831                 // Captured fields
 832                 //
 833                 Hashtable captured_fields = new Hashtable ();
 834                 Hashtable captured_variables = new Hashtable ();
 835                 public Hashtable captured_parameters = new Hashtable ();
 836                 public AnonymousContainer Host;
 837
 838                 public CaptureContext (ToplevelBlock toplevel_owner, Location loc,
 839                                        AnonymousContainer host)
 840                 {
 841                         cc_id = count++;
 842                         this.toplevel_owner = toplevel_owner;
 843                         this.loc = loc;
 844
 845                         if (host != null)
 846                                 Host = host;
 847                 }
 848
 849                 void DoPath (StringBuilder sb, CaptureContext cc)
 850                 {
 851                         if (cc.ParentCaptureContext != null){
 852                                 DoPath (sb, cc.ParentCaptureContext);
 853                                 sb.Append (".");
 854                         }
 855                         sb.Append (cc.cc_id.ToString ());
 856                 }
 857
 858                 public void ReParent (ToplevelBlock new_toplevel, AnonymousContainer new_host)
 859                 {
 860                         toplevel_owner = new_toplevel;
 861                         Host = new_host;
 862
 863                         for (CaptureContext cc = ParentCaptureContext; cc != null;
 864                              cc = cc.ParentCaptureContext) {
 865                                 cc.Host = new_host;
 866                         }
 867                 }
 868
 869                 public override string ToString ()
 870                 {
 871                         StringBuilder sb = new StringBuilder ();
 872                         sb.Append ("[");
 873                         DoPath (sb, this);
 874                         sb.Append ("]");
 875                         return sb.ToString ();
 876                 }
 877
 878                 public ToplevelBlock ParentToplevel {
 879                         get {
 880                                 return toplevel_owner.Container;
 881                         }
 882                 }
 883
 884                 public CaptureContext ParentCaptureContext {
 885                         get {
 886                                 ToplevelBlock parent = ParentToplevel;
 887
 888                                 return (parent == null) ? null : parent.CaptureContext;
 889                         }
 890                 }
 891
 892                 // Returns the deepest of two scopes
 893                 public ScopeInfo Deepest (ScopeInfo a, ScopeInfo b)
 894                 {
 895                         ScopeInfo p;
 896
 897                         if (a == null)
 898                                 return b;
 899                         if (b == null)
 900                                 return a;
 901                         if (a == b)
 902                                 return a;
 903
 904                         //
 905                         // If they Scopes are on the same CaptureContext, we do the double
 906                         // checks just so if there is an invariant change in the future,
 907                         // we get the exception at the end
 908                         //
 909                         for (p = a; p != null; p = p.ParentScope)
 910                                 if (p == b)
 911                                         return a;
 912
 913                         for (p = b; p != null; p = p.ParentScope)
 914                                 if (p == a)
 915                                         return b;
 916
 917                         CaptureContext ca = a.CaptureContext;
 918                         CaptureContext cb = b.CaptureContext;
 919
 920                         for (CaptureContext c = ca; c != null; c = c.ParentCaptureContext)
 921                                 if (c == cb)
 922                                         return a;
 923
 924                         for (CaptureContext c = cb; c != null; c = c.ParentCaptureContext)
 925                                 if (c == ca)
 926                                         return b;
 927                         throw new Exception ("Should never be reached");
 928                 }
 929
 930                 void AdjustMethodScope (AnonymousContainer am, ScopeInfo scope)
 931                 {
 932                         am.Scope = Deepest (am.Scope, scope);
 933                 }
 934
 935                 void LinkScope (ScopeInfo scope, int id)
 936                 {
 937                         ScopeInfo parent = (ScopeInfo) scopes [id];
 938                         if (parent == scope)
 939                                 return;
 940
 941                         scope.ParentScope = parent;
 942                         parent.AddChild (scope);
 943
 944                         if (scope == topmost)
 945                                 topmost = parent;
 946                 }
 947
 948                 public void AddLocal (AnonymousContainer am, LocalInfo li)
 949                 {
 950                         if (li.Block.Toplevel != toplevel_owner){
 951                                 ParentCaptureContext.AddLocal (am, li);
 952                                 return;
 953                         }
 954                         int block_id = li.Block.ID;
 955                         ScopeInfo scope;
 956                         if (scopes [block_id] == null){
 957                                 scope = new ScopeInfo (this, li.Block);
 958                                 scopes [block_id] = scope;
 959                         } else
 960                                 scope = (ScopeInfo) scopes [block_id];
 961
 962                         if (topmost == null){
 963                                 topmost = scope;
 964                         } else {
 965                                 // Link to parent
 966
 967                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
 968                                         if (scopes [b.ID] != null){
 969                                                 LinkScope (scope, b.ID);
 970                                                 break;
 971                                         }
 972                                 }
 973
 974                                 if (scope.ParentScope == null && ParentCaptureContext != null){
 975                                         CaptureContext pcc = ParentCaptureContext;
 976
 977                                         for (Block b = am.ContainingBlock; b != null; b = b.Parent){
 978                                                 if (pcc.scopes [b.ID] != null){
 979                                                         pcc.LinkScope (scope, b.ID);
 980                                                         break;
 981                                                 }
 982                                         }
 983                                 }
 984                         }
 985
 986                         //
 987                         // Adjust the owner
 988                         //
 989                         if (Host != null)
 990                                 AdjustMethodScope (Host, topmost);
 991
 992                         //
 993                         // Adjust the user
 994                         //
 995                         AdjustMethodScope (am, scope);
 996
 997                         if (captured_variables [li] != null)
 998                                 return;
 999
1000                         have_captured_vars = true;
1001                         captured_variables [li] = li;
1002                         scope.AddLocal (li);
1003                 }
1004
1005                 //
1006                 // Retursn the CaptureContext for the block that defines the parameter `name'
1007                 //
1008                 static CaptureContext _ContextForParameter (ToplevelBlock current, string name)
1009                 {
1010                         ToplevelBlock container = current.Container;
1011                         if (container != null){
1012                                 CaptureContext cc = _ContextForParameter (container, name);
1013                                 if (cc != null)
1014                                         return cc;
1015                         }
1016                         if (current.IsParameterReference (name))
1017                                 return current.ToplevelBlockCaptureContext;
1018                         return null;
1019                 }
1020
1021                 static CaptureContext ContextForParameter (ToplevelBlock current, string name)
1022                 {
1023                         CaptureContext cc = _ContextForParameter (current, name);
1024                         if (cc == null)
1025                                 throw new Exception (String.Format ("request for parameteter {0} failed: not found", name));
1026                         return cc;
1027                 }
1028
1029                 //
1030                 // Records the captured parameter at the appropriate CaptureContext
1031                 //
1032                 public void AddParameter (EmitContext ec, AnonymousContainer am,
1033                                           string name, Type t, int idx)
1034                 {
1035                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1036
1037                         cc.AddParameterToContext (am, name, t, idx);
1038                 }
1039
1040                 //
1041                 // Records the parameters in the context
1042                 //
1043                 public void AddParameterToContext (AnonymousContainer am, string name, Type t, int idx)
1044                 {
1045                         if (captured_parameters == null)
1046                                 captured_parameters = new Hashtable ();
1047                         if (captured_parameters [name] == null)
1048                                 captured_parameters [name] = new CapturedParameter (t, idx);
1049
1050                         if (topmost == null){
1051                                 //
1052                                 // Create one ScopeInfo, if there are none.
1053                                 //
1054                                 topmost = new ScopeInfo (this, toplevel_owner);
1055                                 scopes [toplevel_owner.ID] = topmost;
1056                         } else {
1057                                 //
1058                                 // If the topmost ScopeInfo is not at the topblock level, insert
1059                                 // a new ScopeInfo there.
1060                                 //
1061                                 // FIXME: This code probably should be evolved to be like the code
1062                                 // in AddLocal
1063                                 //
1064                                 if (topmost.ScopeBlock != toplevel_owner){
1065                                         ScopeInfo par_si = new ScopeInfo (this, toplevel_owner);
1066                                         ScopeInfo old_top = topmost;
1067                                         scopes [toplevel_owner.ID] = topmost;
1068                                         topmost.ParentScope = par_si;
1069                                         topmost = par_si;
1070                                         topmost.AddChild (old_top);
1071                                 }
1072                         }
1073
1074                         topmost.HostsParameters = true;
1075                         AdjustMethodScope (am, topmost);
1076                 }
1077
1078                 //
1079                 // Captured fields are only recorded on the topmost CaptureContext, because that
1080                 // one is the one linked to the owner of instance fields
1081                 //
1082                 public void AddField (EmitContext ec, AnonymousContainer am, FieldExpr fe)
1083                 {
1084                         if (fe.FieldInfo.IsStatic)
1085                                 throw new Exception ("Attempt to register a static field as a captured field");
1086                         CaptureContext parent = ParentCaptureContext;
1087                         if (parent != null) {
1088                                 parent.AddField (ec, am, fe);
1089                                 return;
1090                         }
1091
1092                         if (topmost == null){
1093                                 //
1094                                 // Create one ScopeInfo, if there are none.
1095                                 //
1096                                 topmost = new ScopeInfo (this, toplevel_owner);
1097                                 scopes [toplevel_owner.ID] = topmost;
1098                         }
1099
1100                         AdjustMethodScope (am, topmost);
1101                 }
1102
1103                 public void CaptureThis (AnonymousContainer am)
1104                 {
1105                         CaptureContext parent = ParentCaptureContext;
1106                         if (parent != null) {
1107                                 parent.CaptureThis (am);
1108                                 return;
1109                         }
1110                         referenced_this = true;
1111
1112                         if (topmost == null){
1113                                 //
1114                                 // Create one ScopeInfo, if there are none.
1115                                 //
1116                                 topmost = new ScopeInfo (this, toplevel_owner);
1117                                 scopes [toplevel_owner.ID] = topmost;
1118
1119                                 AdjustMethodScope (am, topmost);
1120                         }
1121                 }
1122
1123                 public bool HaveCapturedVariables {
1124                         get {
1125                                 return have_captured_vars;
1126                         }
1127                 }
1128
1129                 public bool HaveCapturedFields {
1130                         get {
1131                                 CaptureContext parent = ParentCaptureContext;
1132                                 if (parent != null)
1133                                         return parent.HaveCapturedFields;
1134                                 return captured_fields.Count > 0;
1135                         }
1136                 }
1137
1138                 public bool IsCaptured (LocalInfo local)
1139                 {
1140                         foreach (ScopeInfo si in scopes.Values){
1141                                 if (si.IsCaptured (local))
1142                                         return true;
1143                         }
1144                         return false;
1145                 }
1146
1147                 //
1148                 // Returns whether the parameter is captured
1149                 //
1150                 public bool IsParameterCaptured (string name)
1151                 {
1152                         if (ParentCaptureContext != null && ParentCaptureContext.IsParameterCaptured (name))
1153                                 return true;
1154
1155                         if (captured_parameters != null)
1156                                 return captured_parameters [name] != null;
1157                         return false;
1158                 }
1159
1160                 public void EmitAnonymousHelperClasses (EmitContext ec)
1161                 {
1162                         if (topmost != null){
1163                                 topmost.NeedThis = HaveCapturedFields || referenced_this;
1164                                 topmost.EmitScopeType (ec);
1165                         }
1166                 }
1167
1168                 public void CloseAnonymousHelperClasses ()
1169                 {
1170                         if (topmost != null)
1171                                 topmost.CloseTypes ();
1172                 }
1173
1174                 public void EmitInitScope (EmitContext ec)
1175                 {
1176                         EmitAnonymousHelperClasses (ec);
1177                         if (topmost != null)
1178                                 topmost.EmitInitScope (ec);
1179                 }
1180
1181                 ScopeInfo GetScopeFromBlock (EmitContext ec, Block b)
1182                 {
1183                         ScopeInfo si;
1184
1185                         si = (ScopeInfo) scopes [b.ID];
1186                         if (si == null)
1187                                 throw new Exception ("Si is null for block " + b.ID);
1188                         si.EmitInitScope (ec);
1189
1190                         return si;
1191                 }
1192
1193                 //
1194                 // Emits the opcodes necessary to load the instance of the captured
1195                 // variable in `li'
1196                 //
1197                 public void EmitCapturedVariableInstance (EmitContext ec, LocalInfo li,
1198                                                           AnonymousContainer am)
1199                 {
1200                         ILGenerator ig = ec.ig;
1201                         ScopeInfo si;
1202
1203                         if (li.Block.Toplevel == toplevel_owner){
1204                                 si = GetScopeFromBlock (ec, li.Block);
1205                                 si.EmitScopeInstance (ig);
1206                                 return;
1207                         }
1208
1209                         si = am.Scope;
1210                         ig.Emit (OpCodes.Ldarg_0);
1211                         if (si != null){
1212                                 if (am.IsIterator && (si.ScopeBlock.Toplevel == li.Block.Toplevel)) {
1213                                         return;
1214                                 }
1215
1216                                 while (si.ScopeBlock.ID != li.Block.ID){
1217                                         if (si.ParentLink != null)
1218                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
1219                                         si = si.ParentScope;
1220                                         if (si == null) {
1221                                                 si = am.Scope;
1222                                                 Console.WriteLine ("Target: {0} {1}", li.Block.ID, li.Name);
1223                                                 while (si.ScopeBlock.ID != li.Block.ID){
1224                                                         Console.WriteLine ("Trying: {0}", si.ScopeBlock.ID);
1225                                                         si = si.ParentScope;
1226                                                 }
1227
1228                                                 throw new Exception (
1229                                                              String.Format ("Never found block {0} starting at {1} while looking up {2}",
1230                                                                             li.Block.ID, am.Scope.ScopeBlock.ID, li.Name));
1231                                         }
1232                                 }
1233                         }
1234                 }
1235
1236                 //
1237                 // Internal routine that loads the instance to reach parameter `name'
1238                 //
1239                 void EmitParameterInstance (EmitContext ec, string name)
1240                 {
1241                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1242                         if (cc != this){
1243                                 cc.EmitParameterInstance (ec, name);
1244                                 return;
1245                         }
1246
1247                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1248                         if (par_info != null){
1249                                 //
1250                                 // FIXME: implementing this.
1251                                 //
1252                         }
1253                         ILGenerator ig = ec.ig;
1254
1255                         ScopeInfo si;
1256
1257                         if (ec.CurrentBlock.Toplevel == toplevel_owner) {
1258                                 si = GetScopeFromBlock (ec, toplevel_owner);
1259                                 si.EmitScopeInstance (ig);
1260                         } else {
1261                                 si = ec.CurrentAnonymousMethod.Scope;
1262                                 ig.Emit (OpCodes.Ldarg_0);
1263                         }
1264
1265                         if (si != null){
1266                                 while (si.ParentLink != null) {
1267                                         ig.Emit (OpCodes.Ldfld, si.ParentLink);
1268                                         si = si.ParentScope;
1269                                 }
1270                         }
1271                 }
1272
1273                 //
1274                 // Emits the code necessary to load the parameter named `name' within
1275                 // an anonymous method.
1276                 //
1277                 public void EmitParameter (EmitContext ec, string name, bool leave_copy, bool prepared, ref LocalTemporary temp)
1278                 {
1279                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1280                         if (cc != this){
1281                                 cc.EmitParameter (ec, name, leave_copy, prepared, ref temp);
1282                                 return;
1283                         }
1284                         if (!prepared)
1285                                 EmitParameterInstance (ec, name);
1286                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1287                         if (par_info != null){
1288                                 //
1289                                 // FIXME: implementing this.
1290                                 //
1291                         }
1292                         ec.ig.Emit (OpCodes.Ldfld, par_info.FieldBuilder);
1293
1294                         if (leave_copy){
1295                                 ec.ig.Emit (OpCodes.Dup);
1296                                 temp = new LocalTemporary (ec, par_info.FieldBuilder.FieldType);
1297                                 temp.Store (ec);
1298                         }
1299                 }
1300
1301                 //
1302                 // Implements the assignment of `source' to the paramenter named `name' within
1303                 // an anonymous method.
1304                 //
1305                 public void EmitAssignParameter (EmitContext ec, string name, Expression source, bool leave_copy, bool prepare_for_load, ref LocalTemporary temp)
1306                 {
1307                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1308                         if (cc != this){
1309                                 cc.EmitAssignParameter (ec, name, source, leave_copy, prepare_for_load, ref temp);
1310                                 return;
1311                         }
1312                         ILGenerator ig = ec.ig;
1313                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1314
1315                         EmitParameterInstance (ec, name);
1316                         if (prepare_for_load)
1317                                 ig.Emit (OpCodes.Dup);
1318                         source.Emit (ec);
1319                         if (leave_copy){
1320                                 ig.Emit (OpCodes.Dup);
1321                                 temp = new LocalTemporary (ec, par_info.FieldBuilder.FieldType);
1322                                 temp.Store (ec);
1323                         }
1324                         ig.Emit (OpCodes.Stfld, par_info.FieldBuilder);
1325                         if (temp != null)
1326                                 temp.Emit (ec);
1327                 }
1328
1329                 //
1330                 // Emits the address for the parameter named `name' within
1331                 // an anonymous method.
1332                 //
1333                 public void EmitAddressOfParameter (EmitContext ec, string name)
1334                 {
1335                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1336                         if (cc != this){
1337                                 cc.EmitAddressOfParameter (ec, name);
1338                                 return;
1339                         }
1340                         EmitParameterInstance (ec, name);
1341                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1342                         ec.ig.Emit (OpCodes.Ldflda, par_info.FieldBuilder);
1343                 }
1344
1345                 //
1346                 // The following methods are only invoked on the host for the
1347                 // anonymous method.
1348                 //
1349                 public void EmitMethodHostInstance (EmitContext target, AnonymousContainer am)
1350                 {
1351                         ILGenerator ig = target.ig;
1352                         ScopeInfo si = am.Scope;
1353
1354                         AnonymousContainer container = am.ContainerAnonymousMethod;
1355
1356                         if ((si == null) || ((container != null) && (si == container.Scope))) {
1357                                 ig.Emit (OpCodes.Ldarg_0);
1358                                 return;
1359                         }
1360
1361                         si.EmitInitScope (target);
1362                         si.EmitScopeInstance (ig);
1363                 }
1364
1365                 ArrayList all_scopes = new ArrayList ();
1366
1367                 public void AddScope (ScopeInfo si)
1368                 {
1369                         all_scopes.Add (si);
1370                         toplevel_owner.RegisterCaptureContext (this);
1371                 }
1372
1373                 //
1374                 // Links any scopes that were not linked previously
1375                 //
1376                 public void AdjustScopes ()
1377                 {
1378                         foreach (ScopeInfo scope in all_scopes){
1379                                 if (scope.ParentScope != null)
1380                                         continue;
1381
1382                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
1383                                         if (scopes [b.ID] != null){
1384                                                 LinkScope (scope, b.ID);
1385                                                 break;
1386                                         }
1387                                 }
1388
1389                                 if (scope.ParentScope == null && ParentCaptureContext != null){
1390                                         CaptureContext pcc = ParentCaptureContext;
1391
1392                                         for (Block b = Host.ContainingBlock; b != null; b = b.Parent){
1393                                                 if (pcc.scopes [b.ID] != null){
1394                                                         pcc.LinkScope (scope, b.ID);
1395                                                         break;
1396                                                 }
1397                                         }
1398                                 }
1399                         }
1400                 }
1401         }
1402 }