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