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