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, "Delegate `{0}' does not take `{1}' arguments",
 291                                                 TypeManager.CSharpName (delegate_type), amp.Count);
 292                                         Error_ParameterMismatch (delegate_type);
 293                                 }
 294                                 return null;
 295                         }
 296
 297                         for (int i = 0; i < amp.Count; i++){
 298                                 Parameter.Modifier amp_mod = amp.ParameterModifier (i);
 299
 300                                 if (!probe) {
 301                                         if ((amp_mod & (Parameter.Modifier.OUT | Parameter.Modifier.REF)) != 0){
 302                                                 Report.Error (1677, loc, "Parameter `{0}' should not be declared with the `{1}' keyword",
 303                                                         i+1, amp.ModifierDesc (i));
 304                                                 Error_ParameterMismatch (delegate_type);
 305                                                 return null;
 306                                         }
 307
 308                                         if (amp_mod != invoke_pd.ParameterModifier (i)){
 309                                                 Report.Error (1676, loc, "Parameter `{0}' must be declared with the `{1}' keyword",
 310                                                         i+1, Parameter.GetModifierSignature (invoke_pd.ParameterModifier (i)));
 311                                                 Error_ParameterMismatch (delegate_type);
 312                                                 return null;
 313                                         }
 314
 315                                         if (amp.ParameterType (i) != invoke_pd.ParameterType (i)){
 316                                                 Report.Error (1678, loc, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
 317                                                         i+1,
 318                                                         TypeManager.CSharpName (amp.ParameterType (i)),
 319                                                         TypeManager.CSharpName (invoke_pd.ParameterType (i)));
 320                                                 Error_ParameterMismatch (delegate_type);
 321                                                 return null;
 322                                         }
 323                                 }
 324                         }
 325
 326                         //
 327                         // If we are only probing, return ourselves
 328                         //
 329                         if (probe)
 330                                 return this;
 331
 332                         //
 333                         // Second: the return type of the delegate must be compatible with
 334                         // the anonymous type.   Instead of doing a pass to examine the block
 335                         // we satisfy the rule by setting the return type on the EmitContext
 336                         // to be the delegate type return type.
 337                         //
 338
 339                         //MethodBuilder builder = method_data.MethodBuilder;
 340                         //ILGenerator ig = builder.GetILGenerator ();
 341
 342
 343                         aec = new EmitContext (
 344                                 ec.TypeContainer, ec.DeclSpace, loc, null,
 345                                 invoke_mb.ReturnType,
 346                                 /* REVIEW */ (ec.InIterator ? Modifiers.METHOD_YIELDS : 0) |
 347                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0) |
 348                                 (ec.IsStatic ? Modifiers.STATIC : 0),
 349                                 /* No constructor */ false);
 350
 351                         aec.CurrentAnonymousMethod = this;
 352                         ContainerAnonymousMethod = ec.CurrentAnonymousMethod;
 353                         ContainingBlock = ec.CurrentBlock;
 354
 355                         if (aec.ResolveTopBlock (ec, Block, amp, null, out unreachable))
 356                                 return new AnonymousDelegate (this, delegate_type, loc).Resolve (ec);
 357
 358                         return null;
 359                 }
 360
 361                 public MethodInfo GetMethodBuilder ()
 362                 {
 363                         MethodInfo builder = method.MethodData.MethodBuilder;
 364                         if (TypeArguments != null)
 365                                 return builder.BindGenericParameters (TypeArguments);
 366                         else
 367                                 return builder;
 368                 }
 369
 370                 public override string GetSignatureForError ()
 371                 {
 372                         string s = TypeManager.CSharpSignature (invoke_mb);
 373                         return s.Substring (0, s.IndexOf (".Invoke("));
 374                 }
 375
 376                 public bool EmitMethod (EmitContext ec)
 377                 {
 378                         if (!CreateMethodHost (ec))
 379                                 return false;
 380
 381                         MethodBuilder builder = method.MethodData.MethodBuilder;
 382                         ILGenerator ig = builder.GetILGenerator ();
 383                         aec.ig = ig;
 384
 385                         Parameters.LabelParameters (aec, builder);
 386
 387                         //
 388                         // Adjust based on the computed state of the
 389                         // method from CreateMethodHost
 390
 391                         aec.MethodIsStatic = (method_modifiers & Modifiers.STATIC) != 0;
 392
 393                         aec.EmitMeta (Block, amp);
 394                         aec.EmitResolvedTopBlock (Block, unreachable);
 395                         return true;
 396                 }
 397
 398                 public override void CreateScopeType (EmitContext ec, ScopeInfo scope)
 399                 {
 400                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 401                         string name = String.Format ("<>AnonHelp<{0}>", scope.id);
 402
 403                         scope.ScopeTypeBuilder = container.DefineNestedType (
 404                                 name, TypeAttributes.AutoLayout | TypeAttributes.Class |
 405                                 TypeAttributes.NestedAssembly, TypeManager.object_type, null);
 406
 407                         Type [] constructor_types = TypeManager.NoTypes;
 408                         Parameters constructor_parameters = Parameters.EmptyReadOnlyParameters;
 409                         scope.ScopeConstructor = scope.ScopeTypeBuilder.DefineConstructor (
 410                                 MethodAttributes.Public | MethodAttributes.HideBySig |
 411                                 MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
 412                                 CallingConventions.HasThis, constructor_types);
 413                         InternalParameters parameter_info = new InternalParameters (constructor_types, constructor_parameters);
 414                         TypeManager.RegisterMethod (scope.ScopeConstructor, parameter_info, constructor_types);
 415
 416                         ILGenerator cig = scope.ScopeConstructor.GetILGenerator ();
 417                         cig.Emit (OpCodes.Ldarg_0);
 418                         cig.Emit (OpCodes.Call, TypeManager.object_ctor);
 419                         cig.Emit (OpCodes.Ret);
 420                 }
 421
 422                 public static void Error_AddressOfCapturedVar (string name, Location loc)
 423                 {
 424                         Report.Error (1686, loc,
 425                                 "Local variable `{0}' or its members cannot have their address taken and be used inside an anonymous method block",
 426                                 name);
 427                 }
 428         }
 429
 430         //
 431         // This will emit the code for the delegate, as well delegate creation on the host
 432         //
 433         public class AnonymousDelegate : DelegateCreation {
 434                 AnonymousMethod am;
 435
 436                 public AnonymousDelegate (AnonymousMethod am, Type target_type, Location l)
 437                 {
 438                         type = target_type;
 439                         loc = l;
 440                         this.am = am;
 441                 }
 442
 443                 public override Expression DoResolve (EmitContext ec)
 444                 {
 445                         eclass = ExprClass.Value;
 446
 447                         return this;
 448                 }
 449
 450                 public override void Emit (EmitContext ec)
 451                 {
 452                         if (!am.EmitMethod (ec))
 453                                 return;
 454
 455                         //
 456                         // Now emit the delegate creation.
 457                         //
 458                         if ((am.method.ModFlags & Modifiers.STATIC) == 0)
 459                                 delegate_instance_expression = new AnonymousInstance (am);
 460
 461                         Expression ml = Expression.MemberLookup (ec, type, ".ctor", loc);
 462                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 463                         delegate_method = am.GetMethodBuilder ();
 464                         base.Emit (ec);
 465                 }
 466
 467                 class AnonymousInstance : Expression {
 468                         AnonymousMethod am;
 469
 470                         public AnonymousInstance (AnonymousMethod am)
 471                         {
 472                                 this.am = am;
 473                                 eclass = ExprClass.Value;
 474                         }
 475
 476                         public override Expression DoResolve (EmitContext ec)
 477                         {
 478                                 return this;
 479                         }
 480
 481                         public override void Emit (EmitContext ec)
 482                         {
 483                                 am.aec.EmitMethodHostInstance (ec, am);
 484                         }
 485                 }
 486         }
 487
 488         class CapturedParameter {
 489                 public Type Type;
 490                 public FieldBuilder FieldBuilder;
 491                 public int Idx;
 492
 493                 public CapturedParameter (Type type, int idx)
 494                 {
 495                         Type = type;
 496                         Idx = idx;
 497                 }
 498         }
 499
 500         //
 501         // Here we cluster all the variables captured on a given scope, we also
 502         // keep some extra information that might be required on each scope.
 503         //
 504         public class ScopeInfo {
 505                 public CaptureContext CaptureContext;
 506                 public ScopeInfo ParentScope;
 507                 public Block ScopeBlock;
 508                 public bool NeedThis = false;
 509                 public bool HostsParameters = false;
 510
 511                 // For tracking the number of scopes created.
 512                 public int id;
 513                 static int count;
 514                 bool inited = false;
 515
 516                 ArrayList locals = new ArrayList ();
 517                 ArrayList children = new ArrayList ();
 518
 519                 //
 520                 // The types and fields generated
 521                 //
 522                 public TypeBuilder ScopeTypeBuilder;
 523                 public ConstructorBuilder ScopeConstructor;
 524                 public FieldBuilder THIS;
 525                 public FieldBuilder ParentLink;
 526
 527                 //
 528                 // Points to the object of type `ScopeTypeBuilder' that
 529                 // holds the data for the scope
 530                 //
 531                 LocalBuilder scope_instance;
 532
 533                 public ScopeInfo (CaptureContext cc, Block b)
 534                 {
 535                         CaptureContext = cc;
 536                         ScopeBlock = b;
 537                         id = count++;
 538
 539                         cc.AddScope (this);
 540                 }
 541
 542                 public void AddLocal (LocalInfo li)
 543                 {
 544                         if (locals.Contains (li))
 545                                 return;
 546
 547                         locals.Add (li);
 548 }
 549
 550                 public bool IsCaptured (LocalInfo li)
 551                 {
 552                         return locals.Contains (li);
 553                 }
 554
 555                 internal void AddChild (ScopeInfo si)
 556                 {
 557                         if (children.Contains (si))
 558                                 return;
 559
 560                         //
 561                         // If any of the current children should be a children of `si', move them there
 562                         //
 563                         ArrayList move_queue = null;
 564                         foreach (ScopeInfo child in children){
 565                                 if (child.ScopeBlock.IsChildOf (si.ScopeBlock)){
 566                                         if (move_queue == null)
 567                                                 move_queue = new ArrayList ();
 568                                         move_queue.Add (child);
 569                                         child.ParentScope = si;
 570                                         si.AddChild (child);
 571                                 }
 572                         }
 573
 574                         children.Add (si);
 575
 576                         if (move_queue != null){
 577                                 foreach (ScopeInfo child in move_queue){
 578                                         children.Remove (child);
 579                                 }
 580                         }
 581                 }
 582
 583                 static int indent = 0;
 584
 585                 void Pad ()
 586                 {
 587                         for (int i = 0; i < indent; i++)
 588                                 Console.Write ("    ");
 589                 }
 590
 591                 void EmitDebug ()
 592                 {
 593                         //Console.WriteLine (Environment.StackTrace);
 594                         Pad ();
 595                         Console.WriteLine ("START");
 596                         indent++;
 597                         Pad ();
 598                         Console.WriteLine ("NeedThis=" + NeedThis);
 599                         foreach (LocalInfo li in locals){
 600                                 Pad ();
 601                                 Console.WriteLine ("var {0}", li.Name);
 602                         }
 603
 604                         foreach (ScopeInfo si in children)
 605                                 si.EmitDebug ();
 606                         indent--;
 607                         Pad ();
 608                         Console.WriteLine ("END");
 609                 }
 610
 611                 public string MakeHelperName ()
 612                 {
 613                         return String.Format ("<>AnonHelp<{0}>", id);
 614                 }
 615
 616                 public void EmitScopeType (EmitContext ec)
 617                 {
 618                         // EmitDebug ();
 619
 620                         if (ScopeTypeBuilder != null)
 621                                 return;
 622
 623                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 624
 625                         CaptureContext.Host.CreateScopeType (ec, this);
 626
 627                         if (NeedThis)
 628                                 THIS = ScopeTypeBuilder.DefineField ("<>THIS", container, FieldAttributes.Assembly);
 629
 630                         if (ParentScope != null){
 631                                 if (ParentScope.ScopeTypeBuilder == null){
 632                                         throw new Exception (String.Format ("My parent has not been initialized {0} and {1}", ParentScope, this));
 633                                 }
 634
 635                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder)
 636                                         ParentLink = ScopeTypeBuilder.DefineField ("<>parent", ParentScope.ScopeTypeBuilder,
 637                                                                                    FieldAttributes.Assembly);
 638                         }
 639
 640                         if (NeedThis && ParentScope != null)
 641                                 throw new Exception ("I was not expecting THIS && having a parent");
 642
 643                         foreach (LocalInfo info in locals)
 644                                 info.FieldBuilder = ScopeTypeBuilder.DefineField (
 645                                         info.Name, info.VariableType, FieldAttributes.Assembly);
 646
 647                         if (HostsParameters){
 648                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 649
 650                                 foreach (DictionaryEntry de in captured_parameters){
 651                                         string name = (string) de.Key;
 652                                         CapturedParameter cp = (CapturedParameter) de.Value;
 653                                         FieldBuilder fb;
 654
 655                                         fb = ScopeTypeBuilder.DefineField ("<p:" + name + ">", cp.Type, FieldAttributes.Assembly);
 656                                         cp.FieldBuilder = fb;
 657                                 }
 658                         }
 659
 660                         foreach (ScopeInfo si in children){
 661                                 si.EmitScopeType (ec);
 662                         }
 663                 }
 664
 665                 public void CloseTypes ()
 666                 {
 667                         RootContext.RegisterCompilerGeneratedType (ScopeTypeBuilder);
 668                         foreach (ScopeInfo si in children)
 669                                 si.CloseTypes ();
 670                 }
 671
 672                 //
 673                 // Emits the initialization code for the scope
 674                 //
 675                 public void EmitInitScope (EmitContext ec)
 676                 {
 677                         ILGenerator ig = ec.ig;
 678
 679                         if (inited)
 680                                 return;
 681
 682                         if (ScopeConstructor == null)
 683                                 throw new Exception ("ScopeConstructor is null for" + this.ToString ());
 684
 685                         if (!CaptureContext.Host.IsIterator) {
 686                                 scope_instance = ig.DeclareLocal (ScopeTypeBuilder);
 687                                 ig.Emit (OpCodes.Newobj, (ConstructorInfo) ScopeConstructor);
 688                                 ig.Emit (OpCodes.Stloc, scope_instance);
 689                         }
 690
 691                         if (THIS != null){
 692                                 if (CaptureContext.Host.IsIterator) {
 693                                         ig.Emit (OpCodes.Ldarg_0);
 694                                         ig.Emit (OpCodes.Ldarg_1);
 695                                 } else {
 696                                         ig.Emit (OpCodes.Ldloc, scope_instance);
 697                                         ig.Emit (OpCodes.Ldarg_0);
 698                                 }
 699                                 ig.Emit (OpCodes.Stfld, THIS);
 700                         }
 701
 702                         //
 703                         // Copy the parameter values, if any
 704                         //
 705                         int extra = ec.IsStatic ? 0 : 1;
 706                         if (CaptureContext.Host.IsIterator)
 707                                 extra++;
 708                         if (HostsParameters){
 709                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 710
 711                                 foreach (DictionaryEntry de in captured_parameters){
 712                                         CapturedParameter cp = (CapturedParameter) de.Value;
 713
 714                                         EmitScopeInstance (ig);
 715                                         ParameterReference.EmitLdArg (ig, cp.Idx + extra);
 716                                         ig.Emit (OpCodes.Stfld, cp.FieldBuilder);
 717                                 }
 718                         }
 719
 720                         if (ParentScope != null){
 721                                 if (!ParentScope.inited)
 722                                         ParentScope.EmitInitScope (ec);
 723
 724                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder) {
 725                                         //
 726                                         // Only emit initialization in our capturecontext world
 727                                         //
 728                                         if (ParentScope.CaptureContext == CaptureContext){
 729                                                 EmitScopeInstance (ig);
 730                                                 ParentScope.EmitScopeInstance (ig);
 731                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 732                                         } else {
 733                                                 EmitScopeInstance (ig);
 734                                                 ig.Emit (OpCodes.Ldarg_0);
 735                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 736                                         }
 737                                 }
 738                         }
 739                         inited = true;
 740                 }
 741
 742                 public void EmitScopeInstance (ILGenerator ig)
 743                 {
 744                         if (CaptureContext.Host.IsIterator)
 745                                 ig.Emit (OpCodes.Ldarg_0);
 746                         else
 747                                 ig.Emit (OpCodes.Ldloc, scope_instance);
 748                 }
 749
 750                 static void DoPath (StringBuilder sb, ScopeInfo start)
 751                 {
 752                         if (start.ParentScope != null){
 753                                 DoPath (sb, start.ParentScope);
 754                                 sb.Append (", ");
 755                         }
 756                         sb.Append ((start.id).ToString ());
 757                 }
 758
 759                 public override string ToString ()
 760                 {
 761                         StringBuilder sb = new StringBuilder ();
 762
 763                         sb.Append ("{");
 764                         if (CaptureContext != null){
 765                                 sb.Append (CaptureContext.ToString ());
 766                                 sb.Append (":");
 767                         }
 768
 769                         DoPath (sb, this);
 770                         sb.Append ("}");
 771
 772                         return sb.ToString ();
 773                 }
 774         }
 775
 776         //
 777         // CaptureContext objects are created on demand if a method has
 778         // anonymous methods and kept on the ToplevelBlock.
 779         //
 780         // If they exist, all ToplevelBlocks in the containing block are
 781         // linked together (children pointing to their parents).
 782         //
 783         public class CaptureContext {
 784                 public static int count;
 785                 public int cc_id;
 786                 public Location loc;
 787
 788                 //
 789                 // Points to the toplevel block that owns this CaptureContext
 790                 //
 791                 ToplevelBlock toplevel_owner;
 792                 Hashtable scopes = new Hashtable ();
 793                 bool have_captured_vars = false;
 794                 bool referenced_this = false;
 795                 ScopeInfo topmost = null;
 796
 797                 //
 798                 // Captured fields
 799                 //
 800                 Hashtable captured_fields = new Hashtable ();
 801                 Hashtable captured_variables = new Hashtable ();
 802                 public Hashtable captured_parameters = new Hashtable ();
 803                 public AnonymousContainer Host;
 804
 805                 public CaptureContext (ToplevelBlock toplevel_owner, Location loc,
 806                                        AnonymousContainer host)
 807                 {
 808                         cc_id = count++;
 809                         this.toplevel_owner = toplevel_owner;
 810                         this.loc = loc;
 811
 812                         if (host != null)
 813                                 Host = host;
 814                 }
 815
 816                 void DoPath (StringBuilder sb, CaptureContext cc)
 817                 {
 818                         if (cc.ParentCaptureContext != null){
 819                                 DoPath (sb, cc.ParentCaptureContext);
 820                                 sb.Append (".");
 821                         }
 822                         sb.Append (cc.cc_id.ToString ());
 823                 }
 824
 825                 public void ReParent (ToplevelBlock new_toplevel, AnonymousContainer new_host)
 826                 {
 827                         toplevel_owner = new_toplevel;
 828                         Host = new_host;
 829
 830                         for (CaptureContext cc = ParentCaptureContext; cc != null;
 831                              cc = cc.ParentCaptureContext) {
 832                                 cc.Host = new_host;
 833                         }
 834                 }
 835
 836                 public override string ToString ()
 837                 {
 838                         StringBuilder sb = new StringBuilder ();
 839                         sb.Append ("[");
 840                         DoPath (sb, this);
 841                         sb.Append ("]");
 842                         return sb.ToString ();
 843                 }
 844
 845                 public ToplevelBlock ParentToplevel {
 846                         get {
 847                                 return toplevel_owner.Container;
 848                         }
 849                 }
 850
 851                 public CaptureContext ParentCaptureContext {
 852                         get {
 853                                 ToplevelBlock parent = ParentToplevel;
 854
 855                                 return (parent == null) ? null : parent.CaptureContext;
 856                         }
 857                 }
 858
 859                 // Returns the deepest of two scopes
 860                 public ScopeInfo Deepest (ScopeInfo a, ScopeInfo b)
 861                 {
 862                         ScopeInfo p;
 863
 864                         if (a == null)
 865                                 return b;
 866                         if (b == null)
 867                                 return a;
 868                         if (a == b)
 869                                 return a;
 870
 871                         //
 872                         // If they Scopes are on the same CaptureContext, we do the double
 873                         // checks just so if there is an invariant change in the future,
 874                         // we get the exception at the end
 875                         //
 876                         for (p = a; p != null; p = p.ParentScope)
 877                                 if (p == b)
 878                                         return a;
 879
 880                         for (p = b; p != null; p = p.ParentScope)
 881                                 if (p == a)
 882                                         return b;
 883
 884                         CaptureContext ca = a.CaptureContext;
 885                         CaptureContext cb = b.CaptureContext;
 886
 887                         for (CaptureContext c = ca; c != null; c = c.ParentCaptureContext)
 888                                 if (c == cb)
 889                                         return a;
 890
 891                         for (CaptureContext c = cb; c != null; c = c.ParentCaptureContext)
 892                                 if (c == ca)
 893                                         return b;
 894                         throw new Exception ("Should never be reached");
 895                 }
 896
 897                 void AdjustMethodScope (AnonymousContainer am, ScopeInfo scope)
 898                 {
 899                         am.Scope = Deepest (am.Scope, scope);
 900                 }
 901
 902                 void LinkScope (ScopeInfo scope, int id)
 903                 {
 904                         ScopeInfo parent = (ScopeInfo) scopes [id];
 905                         scope.ParentScope = parent;
 906                         parent.AddChild (scope);
 907
 908                         if (scope == topmost)
 909                                 topmost = parent;
 910                 }
 911
 912                 public void AddLocal (AnonymousContainer am, LocalInfo li)
 913                 {
 914                         if (li.Block.Toplevel != toplevel_owner){
 915                                 ParentCaptureContext.AddLocal (am, li);
 916                                 return;
 917                         }
 918                         int block_id = li.Block.ID;
 919                         ScopeInfo scope;
 920                         if (scopes [block_id] == null){
 921                                 scope = new ScopeInfo (this, li.Block);
 922                                 scopes [block_id] = scope;
 923                         } else
 924                                 scope = (ScopeInfo) scopes [block_id];
 925
 926                         if (topmost == null){
 927                                 topmost = scope;
 928                         } else {
 929                                 // Link to parent
 930
 931                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
 932                                         if (scopes [b.ID] != null){
 933                                                 LinkScope (scope, b.ID);
 934                                                 break;
 935                                         }
 936                                 }
 937
 938                                 if (scope.ParentScope == null && ParentCaptureContext != null){
 939                                         CaptureContext pcc = ParentCaptureContext;
 940
 941                                         for (Block b = am.ContainingBlock; b != null; b = b.Parent){
 942                                                 if (pcc.scopes [b.ID] != null){
 943                                                         pcc.LinkScope (scope, b.ID);
 944                                                         break;
 945                                                 }
 946                                         }
 947                                 }
 948                         }
 949
 950                         //
 951                         // Adjust the owner
 952                         //
 953                         if (Host != null)
 954                                 AdjustMethodScope (Host, topmost);
 955
 956                         //
 957                         // Adjust the user
 958                         //
 959                         AdjustMethodScope (am, scope);
 960
 961                         if (captured_variables [li] != null)
 962                                 return;
 963
 964                         have_captured_vars = true;
 965                         captured_variables [li] = li;
 966                         scope.AddLocal (li);
 967                 }
 968
 969                 //
 970                 // Retursn the CaptureContext for the block that defines the parameter `name'
 971                 //
 972                 static CaptureContext _ContextForParameter (ToplevelBlock current, string name)
 973                 {
 974                         ToplevelBlock container = current.Container;
 975                         if (container != null){
 976                                 CaptureContext cc = _ContextForParameter (container, name);
 977                                 if (cc != null)
 978                                         return cc;
 979                         }
 980                         if (current.IsParameterReference (name))
 981                                 return current.ToplevelBlockCaptureContext;
 982                         return null;
 983                 }
 984
 985                 static CaptureContext ContextForParameter (ToplevelBlock current, string name)
 986                 {
 987                         CaptureContext cc = _ContextForParameter (current, name);
 988                         if (cc == null)
 989                                 throw new Exception (String.Format ("request for parameteter {0} failed: not found", name));
 990                         return cc;
 991                 }
 992
 993                 //
 994                 // Records the captured parameter at the appropriate CaptureContext
 995                 //
 996                 public void AddParameter (EmitContext ec, AnonymousContainer am,
 997                                           string name, Type t, int idx)
 998                 {
 999                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1000
1001                         cc.AddParameterToContext (am, name, t, idx);
1002                 }
1003
1004                 //
1005                 // Records the parameters in the context
1006                 //
1007                 public void AddParameterToContext (AnonymousContainer am, string name, Type t, int idx)
1008                 {
1009                         if (captured_parameters == null)
1010                                 captured_parameters = new Hashtable ();
1011                         if (captured_parameters [name] != null)
1012                                 return;
1013                         captured_parameters [name] = new CapturedParameter (t, idx);
1014
1015                         if (topmost == null){
1016                                 //
1017                                 // Create one ScopeInfo, if there are none.
1018                                 //
1019                                 topmost = new ScopeInfo (this, toplevel_owner);
1020                                 scopes [toplevel_owner.ID] = topmost;
1021                         } else {
1022                                 //
1023                                 // If the topmost ScopeInfo is not at the topblock level, insert
1024                                 // a new ScopeInfo there.
1025                                 //
1026                                 // FIXME: This code probably should be evolved to be like the code
1027                                 // in AddLocal
1028                                 //
1029                                 if (topmost.ScopeBlock != toplevel_owner){
1030                                         ScopeInfo par_si = new ScopeInfo (this, toplevel_owner);
1031                                         ScopeInfo old_top = topmost;
1032                                         scopes [toplevel_owner.ID] = topmost;
1033                                         topmost.ParentScope = par_si;
1034                                         topmost = par_si;
1035                                         topmost.AddChild (old_top);
1036                                 }
1037                         }
1038
1039                         topmost.HostsParameters = true;
1040                         AdjustMethodScope (am, topmost);
1041                 }
1042
1043                 //
1044                 // Captured fields are only recorded on the topmost CaptureContext, because that
1045                 // one is the one linked to the owner of instance fields
1046                 //
1047                 public void AddField (FieldExpr fe)
1048                 {
1049                         if (fe.FieldInfo.IsStatic)
1050                                 throw new Exception ("Attempt to register a static field as a captured field");
1051
1052                         CaptureContext parent = ParentCaptureContext;
1053                         if (parent != null)
1054                                 parent.AddField (fe);
1055                         else
1056                                 captured_fields [fe] = fe;
1057                 }
1058
1059                 public void CaptureThis ()
1060                 {
1061                         CaptureContext parent = ParentCaptureContext;
1062                         if (parent != null)
1063                                 parent.CaptureThis ();
1064                         referenced_this = true;
1065                 }
1066
1067                 public bool HaveCapturedVariables {
1068                         get {
1069                                 return have_captured_vars;
1070                         }
1071                 }
1072
1073                 public bool HaveCapturedFields {
1074                         get {
1075                                 CaptureContext parent = ParentCaptureContext;
1076                                 if (parent != null)
1077                                         return parent.HaveCapturedFields;
1078                                 return captured_fields.Count > 0;
1079                         }
1080                 }
1081
1082                 public bool IsCaptured (LocalInfo local)
1083                 {
1084                         foreach (ScopeInfo si in scopes.Values){
1085                                 if (si.IsCaptured (local))
1086                                         return true;
1087                         }
1088                         return false;
1089                 }
1090
1091                 //
1092                 // Returns whether the parameter is captured
1093                 //
1094                 public bool IsParameterCaptured (string name)
1095                 {
1096                         if (ParentCaptureContext != null && ParentCaptureContext.IsParameterCaptured (name))
1097                                 return true;
1098
1099                         if (captured_parameters != null)
1100                                 return captured_parameters [name] != null;
1101                         return false;
1102                 }
1103
1104                 public void EmitAnonymousHelperClasses (EmitContext ec)
1105                 {
1106                         if (topmost != null){
1107                                 topmost.NeedThis = HaveCapturedFields || referenced_this;
1108                                 topmost.EmitScopeType (ec);
1109                         }
1110                 }
1111
1112                 public void CloseAnonymousHelperClasses ()
1113                 {
1114                         if (topmost != null)
1115                                 topmost.CloseTypes ();
1116                 }
1117
1118                 public void EmitInitScope (EmitContext ec)
1119                 {
1120                         EmitAnonymousHelperClasses (ec);
1121                         if (topmost != null)
1122                                 topmost.EmitInitScope (ec);
1123                 }
1124
1125                 ScopeInfo GetScopeFromBlock (EmitContext ec, Block b)
1126                 {
1127                         ScopeInfo si;
1128
1129                         si = (ScopeInfo) scopes [b.ID];
1130                         if (si == null)
1131                                 throw new Exception ("Si is null for block " + b.ID);
1132                         si.EmitInitScope (ec);
1133
1134                         return si;
1135                 }
1136
1137                 //
1138                 // Emits the opcodes necessary to load the instance of the captured
1139                 // variable in `li'
1140                 //
1141                 public void EmitCapturedVariableInstance (EmitContext ec, LocalInfo li,
1142                                                           AnonymousContainer am)
1143                 {
1144                         ILGenerator ig = ec.ig;
1145                         ScopeInfo si;
1146
1147                         if (li.Block.Toplevel == toplevel_owner){
1148                                 si = GetScopeFromBlock (ec, li.Block);
1149                                 si.EmitScopeInstance (ig);
1150                                 return;
1151                         }
1152
1153                         si = am.Scope;
1154                         ig.Emit (OpCodes.Ldarg_0);
1155                         if (si != null){
1156                                 if (am.IsIterator && (si.ScopeBlock.Toplevel == li.Block.Toplevel)) {
1157                                         return;
1158                                 }
1159
1160                                 while (si.ScopeBlock.ID != li.Block.ID){
1161                                         if (si.ParentLink != null)
1162                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
1163                                         si = si.ParentScope;
1164                                         if (si == null) {
1165                                                 si = am.Scope;
1166                                                 Console.WriteLine ("Target: {0} {1}", li.Block.ID, li.Name);
1167                                                 while (si.ScopeBlock.ID != li.Block.ID){
1168                                                         Console.WriteLine ("Trying: {0}", si.ScopeBlock.ID);
1169                                                         si = si.ParentScope;
1170                                                 }
1171
1172                                                 throw new Exception (
1173                                                              String.Format ("Never found block {0} starting at {1} while looking up {2}",
1174                                                                             li.Block.ID, am.Scope.ScopeBlock.ID, li.Name));
1175                                         }
1176                                 }
1177                         }
1178                 }
1179
1180                 //
1181                 // Internal routine that loads the instance to reach parameter `name'
1182                 //
1183                 void EmitParameterInstance (EmitContext ec, string name)
1184                 {
1185                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1186                         if (cc != this){
1187                                 cc.EmitParameterInstance (ec, name);
1188                                 return;
1189                         }
1190
1191                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1192                         if (par_info != null){
1193                                 //
1194                                 // FIXME: implementing this.
1195                                 //
1196                         }
1197                         ILGenerator ig = ec.ig;
1198
1199                         ScopeInfo si;
1200
1201                         if (ec.CurrentBlock.Toplevel == toplevel_owner) {
1202                                 si = GetScopeFromBlock (ec, toplevel_owner);
1203                                 si.EmitScopeInstance (ig);
1204                         } else {
1205                                 si = ec.CurrentAnonymousMethod.Scope;
1206                                 ig.Emit (OpCodes.Ldarg_0);
1207                         }
1208
1209                         if (si != null){
1210                                 while (si.ParentLink != null) {
1211                                         ig.Emit (OpCodes.Ldfld, si.ParentLink);
1212                                         si = si.ParentScope;
1213                                 }
1214                         }
1215                 }
1216
1217                 //
1218                 // Emits the code necessary to load the parameter named `name' within
1219                 // an anonymous method.
1220                 //
1221                 public void EmitParameter (EmitContext ec, string name)
1222                 {
1223                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1224                         if (cc != this){
1225                                 cc.EmitParameter (ec, name);
1226                                 return;
1227                         }
1228                         EmitParameterInstance (ec, name);
1229                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1230                         if (par_info != null){
1231                                 //
1232                                 // FIXME: implementing this.
1233                                 //
1234                         }
1235                         ec.ig.Emit (OpCodes.Ldfld, par_info.FieldBuilder);
1236                 }
1237
1238                 //
1239                 // Implements the assignment of `source' to the paramenter named `name' within
1240                 // an anonymous method.
1241                 //
1242                 public void EmitAssignParameter (EmitContext ec, string name, Expression source, bool leave_copy, bool prepare_for_load)
1243                 {
1244                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1245                         if (cc != this){
1246                                 cc.EmitAssignParameter (ec, name, source, leave_copy, prepare_for_load);
1247                                 return;
1248                         }
1249                         ILGenerator ig = ec.ig;
1250                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1251
1252                         EmitParameterInstance (ec, name);
1253                         source.Emit (ec);
1254                         if (leave_copy)
1255                                 ig.Emit (OpCodes.Dup);
1256                         ig.Emit (OpCodes.Stfld, par_info.FieldBuilder);
1257                 }
1258
1259                 //
1260                 // Emits the address for the parameter named `name' within
1261                 // an anonymous method.
1262                 //
1263                 public void EmitAddressOfParameter (EmitContext ec, string name)
1264                 {
1265                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1266                         if (cc != this){
1267                                 cc.EmitAddressOfParameter (ec, name);
1268                                 return;
1269                         }
1270                         EmitParameterInstance (ec, name);
1271                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1272                         ec.ig.Emit (OpCodes.Ldflda, par_info.FieldBuilder);
1273                 }
1274
1275                 //
1276                 // The following methods are only invoked on the host for the
1277                 // anonymous method.
1278                 //
1279                 public void EmitMethodHostInstance (EmitContext target, AnonymousContainer am)
1280                 {
1281                         ILGenerator ig = target.ig;
1282                         ScopeInfo si = am.Scope;
1283
1284                         if (si == null){
1285                                 ig.Emit (OpCodes.Ldarg_0);
1286                                 return;
1287                         }
1288
1289                         si.EmitInitScope (target);
1290                         si.EmitScopeInstance (ig);
1291                 }
1292
1293                 ArrayList all_scopes = new ArrayList ();
1294
1295                 public void AddScope (ScopeInfo si)
1296                 {
1297                         all_scopes.Add (si);
1298                         toplevel_owner.RegisterCaptureContext (this);
1299                 }
1300
1301                 //
1302                 // Links any scopes that were not linked previously
1303                 //
1304                 public void AdjustScopes ()
1305                 {
1306                         foreach (ScopeInfo scope in all_scopes){
1307                                 if (scope.ParentScope != null)
1308                                         continue;
1309
1310                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
1311                                         if (scopes [b.ID] != null){
1312                                                 LinkScope (scope, b.ID);
1313                                                 break;
1314                                         }
1315                                 }
1316
1317                                 if (scope.ParentScope == null && ParentCaptureContext != null){
1318                                         CaptureContext pcc = ParentCaptureContext;
1319
1320                                         for (Block b = Host.ContainingBlock; b != null; b = b.Parent){
1321                                                 if (pcc.scopes [b.ID] != null){
1322                                                         pcc.LinkScope (scope, b.ID);
1323                                                         break;
1324                                                 }
1325                                         }
1326                                 }
1327                         }
1328                 }
1329         }
1330 }