mcs/mcs/anonymous.cs

   1 //
   2 // anonymous.cs: Support for anonymous methods
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximain.com)
   6 //
   7 // (C) 2003, 2004 Novell, Inc.
   8 //
   9 // TODO: Ideally, we should have the helper classes emited as a hierarchy to map
  10 // their nesting, and have the visibility set to private, instead of NestedAssembly
  11 //
  12 //
  13 //
  14
  15 using System;
  16 using System.Text;
  17 using System.Collections;
  18 using System.Reflection;
  19 using System.Reflection.Emit;
  20
  21 namespace Mono.CSharp {
  22
  23         public abstract class AnonymousContainer : Expression
  24         {
  25                 // Used to generate unique method names.
  26                 protected static int anonymous_method_count;
  27
  28                 // An array list of AnonymousMethodParameter or null
  29                 public Parameters Parameters;
  30
  31                 //
  32                 // The block that makes up the body for the anonymous mehtod
  33                 //
  34                 public ToplevelBlock Block;
  35
  36                 //
  37                 // The container block for this anonymous method.
  38                 //
  39                 public Block ContainingBlock;
  40
  41                 //
  42                 // The implicit method we create
  43                 //
  44                 public Method method;
  45
  46                 protected MethodInfo invoke_mb;
  47
  48                 // The emit context for the anonymous method
  49                 public EmitContext aec;
  50                 public Parameters amp;
  51                 protected bool unreachable;
  52
  53                 // The method scope
  54                 ScopeInfo method_scope;
  55                 bool computed_method_scope = false;
  56
  57                 //
  58                 // The modifiers applied to the method, we aggregate them
  59                 //
  60                 protected int method_modifiers = Modifiers.PRIVATE;
  61
  62                 //
  63                 // Track the scopes that this method has used.  At the
  64                 // end this is used to determine the ScopeInfo that will
  65                 // host the method
  66                 //
  67                 ArrayList scopes_used = new ArrayList ();
  68
  69                 //
  70                 // Points to our container anonymous method if its present
  71                 //
  72                 public AnonymousContainer ContainerAnonymousMethod;
  73
  74                 protected AnonymousContainer (Parameters parameters, ToplevelBlock container,
  75                                               ToplevelBlock block, Location l)
  76                 {
  77                         Parameters = parameters;
  78                         Block = block;
  79                         loc = l;
  80
  81                         //
  82                         // The order is important: this setups the CaptureContext tree hierarchy.
  83                         //
  84                         if (container == null) {
  85                                 Report.Error (1706, l, "Anonymous methods are not allowed in attribute declaration");
  86                                 return;
  87                         }
  88                         container.SetHaveAnonymousMethods (l, this);
  89                         block.SetHaveAnonymousMethods (l, this);
  90                 }
  91
  92                 protected AnonymousContainer (Parameters parameters, ToplevelBlock container,
  93                                               Location l):
  94                         this (parameters, container, new ToplevelBlock (container, parameters, l), l)
  95                 {
  96                 }
  97
  98                 public override Expression DoResolve (EmitContext ec)
  99                 {
 100                         //
 101                         // Set class type, set type
 102                         //
 103
 104                         eclass = ExprClass.Value;
 105
 106                         //
 107                         // This hack means `The type is not accessible
 108                         // anywhere', we depend on special conversion
 109                         // rules.
 110                         //
 111                         type = TypeManager.anonymous_method_type;
 112
 113                         return this;
 114                 }
 115
 116                 public void RegisterScope (ScopeInfo scope)
 117                 {
 118                         if (scopes_used.Contains (scope))
 119                                 return;
 120                         scopes_used.Add (scope);
 121                 }
 122
 123                 // Returns the deepest of two scopes
 124                 ScopeInfo Deepest (ScopeInfo a, ScopeInfo b)
 125                 {
 126                         ScopeInfo p;
 127
 128                         if (a == null)
 129                                 return b;
 130                         if (b == null)
 131                                 return a;
 132                         if (a == b)
 133                                 return a;
 134
 135                         //
 136                         // If they Scopes are on the same CaptureContext, we do the double
 137                         // checks just so if there is an invariant change in the future,
 138                         // we get the exception at the end
 139                         //
 140                         for (p = a; p != null; p = p.ParentScope)
 141                                 if (p == b)
 142                                         return a;
 143
 144                         for (p = b; p != null; p = p.ParentScope)
 145                                 if (p == a)
 146                                         return b;
 147
 148                         CaptureContext ca = a.CaptureContext;
 149                         CaptureContext cb = b.CaptureContext;
 150
 151                         for (CaptureContext c = ca; c != null; c = c.ParentCaptureContext)
 152                                 if (c == cb)
 153                                         return a;
 154
 155                         for (CaptureContext c = cb; c != null; c = c.ParentCaptureContext)
 156                                 if (c == ca)
 157                                         return b;
 158                         throw new Exception ("Should never be reached");
 159                 }
 160
 161                 //
 162                 // Determines the proper host for a method considering the
 163                 // scopes it references
 164                 //
 165                 public void ComputeMethodHost ()
 166                 {
 167                         if (computed_method_scope)
 168                                 return;
 169
 170                         method_scope = null;
 171                         int top = scopes_used.Count;
 172                         computed_method_scope = true;
 173
 174                         if (top == 0)
 175                                 return;
 176
 177                         method_scope = (ScopeInfo) scopes_used [0];
 178                         if (top == 1)
 179                                 return;
 180
 181                         for (int i = 1; i < top; i++)
 182                                 method_scope = Deepest (method_scope, (ScopeInfo) scopes_used [i]);
 183                 }
 184
 185                 public ScopeInfo Scope {
 186                         get {
 187                                 if (computed_method_scope)
 188                                         return method_scope;
 189
 190                                 //
 191                                 // This means that ComputeMethodHost is not being called, most
 192                                 // likely by someone who overwrote the CreateMethodHost method
 193                                 //
 194                                 throw new Exception ("Internal error, AnonymousContainer.Scope is being used before its container is computed");
 195                         }
 196                 }
 197
 198
 199                 protected abstract bool CreateMethodHost (EmitContext ec);
 200
 201                 public abstract void CreateScopeType (EmitContext ec, ScopeInfo scope);
 202
 203                 public abstract bool IsIterator {
 204                         get;
 205                 }
 206         }
 207
 208         public class AnonymousMethod : AnonymousContainer
 209         {
 210                 public AnonymousMethod (Parameters parameters, ToplevelBlock container,
 211                                         ToplevelBlock block, Location l)
 212                         : base (parameters, container, block, l)
 213                 {
 214                 }
 215
 216                 public override bool IsIterator {
 217                         get { return false; }
 218                 }
 219
 220                 public override void Emit (EmitContext ec)
 221                 {
 222                         // nothing, as we only exist to not do anything.
 223                 }
 224
 225                 //
 226                 // Creates the host for the anonymous method
 227                 //
 228                 protected override bool CreateMethodHost (EmitContext ec)
 229                 {
 230                         ComputeMethodHost ();
 231
 232                         //
 233                         // Crude hack follows: we replace the TypeBuilder during the
 234                         // definition to get the method hosted in the right class
 235                         //
 236                         TypeBuilder current_type = ec.TypeContainer.TypeBuilder;
 237                         TypeBuilder type_host = (Scope == null ) ? current_type : Scope.ScopeTypeBuilder;
 238
 239                         if (current_type == null)
 240                                 throw new Exception ("The current_type is null");
 241
 242                         if (type_host == null)
 243                                 throw new Exception (String.Format ("Type host is null, method_host is {0}", Scope == null ? "null" : "Not null"));
 244
 245                         if (current_type != type_host)
 246                                 method_modifiers = Modifiers.INTERNAL;
 247
 248                         if (current_type == type_host && ec.IsStatic){
 249                                 method_modifiers |= Modifiers.STATIC;
 250                                 current_type = null;
 251                         }
 252
 253                         method = new Method (
 254                                 (TypeContainer) ec.TypeContainer,
 255                                 new TypeExpression (invoke_mb.ReturnType, loc),
 256                                 method_modifiers, false, new MemberName ("<#AnonymousMethod>" + anonymous_method_count++, loc),
 257                                 Parameters, null);
 258                         method.Block = Block;
 259
 260                         //
 261                         // Swap the TypeBuilder while we define the method, then restore
 262                         //
 263                         if (current_type != null)
 264                                 ec.TypeContainer.TypeBuilder = type_host;
 265                         bool res = method.Define ();
 266                         if (current_type != null)
 267                                 ec.TypeContainer.TypeBuilder = current_type;
 268                         return res;
 269                 }
 270
 271                 void Error_ParameterMismatch (Type t)
 272                 {
 273                         Report.Error (1661, loc, "Anonymous method could not be converted to delegate `" +
 274                                       "{0}' since there is a parameter mismatch", TypeManager.CSharpName (t));
 275                 }
 276
 277                 //
 278                 // Returns true if this anonymous method can be implicitly
 279                 // converted to the delegate type `delegate_type'
 280                 //
 281                 public Expression Compatible (EmitContext ec, Type delegate_type, bool probe)
 282                 {
 283                         //
 284                         // At this point its the first time we know the return type that is
 285                         // needed for the anonymous method.  We create the method here.
 286                         //
 287
 288                         invoke_mb = (MethodInfo) Delegate.GetInvokeMethod (ec, delegate_type, loc);
 289                         ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
 290
 291                         if (Parameters == null){
 292                                 //
 293                                 // We provide a set of inaccessible parameters
 294                                 //
 295                                 Parameter [] fixedpars = new Parameter [invoke_pd.Count];
 296
 297                                 for (int i = 0; i < invoke_pd.Count; i++){
 298                                         fixedpars [i] = new Parameter (
 299                                                 invoke_pd.ParameterType (i),
 300                                                 "+" + i, invoke_pd.ParameterModifier (i), null, loc);
 301                                 }
 302
 303                                 Parameters = new Parameters (fixedpars);
 304                         }
 305
 306                         //
 307                         // First, parameter types of `delegate_type' must be compatible
 308                         // with the anonymous method.
 309                         //
 310                         Parameters.Resolve (ec);
 311                         amp = Parameters;
 312
 313                         if (amp.Count != invoke_pd.Count){
 314                                 if (!probe){
 315                                         Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
 316                                                 TypeManager.CSharpName (delegate_type), amp.Count.ToString ());
 317                                         Error_ParameterMismatch (delegate_type);
 318                                 }
 319                                 return null;
 320                         }
 321
 322                         for (int i = 0; i < amp.Count; i++){
 323                                 Parameter.Modifier amp_mod = amp.ParameterModifier (i);
 324
 325                                 if (!probe) {
 326                                         if (amp_mod != invoke_pd.ParameterModifier (i)){
 327                                                 Report.Error (1676, loc, "Parameter `{0}' must be declared with the `{1}' keyword",
 328                                                         (i+1).ToString (), Parameter.GetModifierSignature (invoke_pd.ParameterModifier (i)));
 329                                                 Error_ParameterMismatch (delegate_type);
 330                                                 return null;
 331                                         }
 332
 333                                         if (amp.ParameterType (i) != invoke_pd.ParameterType (i)){
 334                                                 Report.Error (1678, loc, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
 335                                                         (i+1).ToString (),
 336                                                         TypeManager.CSharpName (amp.ParameterType (i)),
 337                                                         TypeManager.CSharpName (invoke_pd.ParameterType (i)));
 338                                                 Error_ParameterMismatch (delegate_type);
 339                                                 return null;
 340                                         }
 341                                 }
 342                         }
 343
 344                         //
 345                         // If we are only probing, return ourselves
 346                         //
 347                         if (probe)
 348                                 return this;
 349
 350                         //
 351                         // Second: the return type of the delegate must be compatible with
 352                         // the anonymous type.   Instead of doing a pass to examine the block
 353                         // we satisfy the rule by setting the return type on the EmitContext
 354                         // to be the delegate type return type.
 355                         //
 356
 357                         //MethodBuilder builder = method_data.MethodBuilder;
 358                         //ILGenerator ig = builder.GetILGenerator ();
 359
 360
 361                         aec = new EmitContext (
 362                                 ec.TypeContainer, ec.DeclSpace, loc, null,
 363                                 invoke_mb.ReturnType,
 364                                 /* REVIEW */ (ec.InIterator ? Modifiers.METHOD_YIELDS : 0) |
 365                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0) |
 366                                 (ec.IsStatic ? Modifiers.STATIC : 0),
 367                                 /* No constructor */ false);
 368
 369                         aec.CurrentAnonymousMethod = this;
 370                         ContainerAnonymousMethod = ec.CurrentAnonymousMethod;
 371                         ContainingBlock = ec.CurrentBlock;
 372
 373                         if (aec.ResolveTopBlock (ec, Block, amp, null, out unreachable))
 374                                 return new AnonymousDelegate (this, delegate_type, loc).Resolve (ec);
 375
 376                         return null;
 377                 }
 378
 379                 public override string ExprClassName {
 380                         get {
 381                                 return "anonymous method";
 382                         }
 383                 }
 384
 385                 public MethodBuilder GetMethodBuilder ()
 386                 {
 387                         return method.MethodData.MethodBuilder;
 388                 }
 389
 390                 public override string GetSignatureForError ()
 391                 {
 392                         string s = TypeManager.CSharpSignature (invoke_mb);
 393                         return s.Substring (0, s.IndexOf (".Invoke("));
 394                 }
 395
 396                 public bool EmitMethod (EmitContext ec)
 397                 {
 398                         if (!CreateMethodHost (ec))
 399                                 return false;
 400
 401                         MethodBuilder builder = GetMethodBuilder ();
 402                         ILGenerator ig = builder.GetILGenerator ();
 403                         aec.ig = ig;
 404
 405                         Parameters.ApplyAttributes (aec, builder);
 406
 407                         //
 408                         // Adjust based on the computed state of the
 409                         // method from CreateMethodHost
 410
 411                         aec.MethodIsStatic = (method_modifiers & Modifiers.STATIC) != 0;
 412
 413                         aec.EmitMeta (Block);
 414                         aec.EmitResolvedTopBlock (Block, unreachable);
 415                         return true;
 416                 }
 417
 418                 public override void CreateScopeType (EmitContext ec, ScopeInfo scope)
 419                 {
 420                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 421                         string name = String.Format ("<>AnonHelp<{0}>", scope.id);
 422
 423                         scope.ScopeTypeBuilder = container.DefineNestedType (
 424                                 name, TypeAttributes.AutoLayout | TypeAttributes.Class |
 425                                 TypeAttributes.NestedAssembly, TypeManager.object_type, null);
 426
 427                         Type [] constructor_types = TypeManager.NoTypes;
 428                         scope.ScopeConstructor = scope.ScopeTypeBuilder.DefineConstructor (
 429                                 MethodAttributes.Public | MethodAttributes.HideBySig |
 430                                 MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
 431                                 CallingConventions.HasThis, constructor_types);
 432
 433                         TypeManager.RegisterMethod (scope.ScopeConstructor, Parameters.EmptyReadOnlyParameters);
 434
 435                         ILGenerator cig = scope.ScopeConstructor.GetILGenerator ();
 436                         cig.Emit (OpCodes.Ldarg_0);
 437                         cig.Emit (OpCodes.Call, TypeManager.object_ctor);
 438                         cig.Emit (OpCodes.Ret);
 439                 }
 440
 441                 public static void Error_AddressOfCapturedVar (string name, Location loc)
 442                 {
 443                         Report.Error (1686, loc,
 444                                 "Local variable `{0}' or its members cannot have their address taken and be used inside an anonymous method block",
 445                                 name);
 446                 }
 447         }
 448
 449         //
 450         // This will emit the code for the delegate, as well delegate creation on the host
 451         //
 452         public class AnonymousDelegate : DelegateCreation {
 453                 AnonymousMethod am;
 454
 455                 public AnonymousDelegate (AnonymousMethod am, Type target_type, Location l)
 456                 {
 457                         type = target_type;
 458                         loc = l;
 459                         this.am = am;
 460                 }
 461
 462                 public override Expression DoResolve (EmitContext ec)
 463                 {
 464                         eclass = ExprClass.Value;
 465
 466                         return this;
 467                 }
 468
 469                 public override void Emit (EmitContext ec)
 470                 {
 471                         if (!am.EmitMethod (ec))
 472                                 return;
 473
 474                         //
 475                         // Now emit the delegate creation.
 476                         //
 477                         if ((am.method.ModFlags & Modifiers.STATIC) == 0)
 478                                 delegate_instance_expression = new AnonymousInstance (am);
 479
 480                         Expression ml = Expression.MemberLookup (ec, type, ".ctor", loc);
 481                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 482                         delegate_method = am.GetMethodBuilder ();
 483                         base.Emit (ec);
 484                 }
 485
 486                 class AnonymousInstance : Expression {
 487                         AnonymousMethod am;
 488
 489                         public AnonymousInstance (AnonymousMethod am)
 490                         {
 491                                 this.am = am;
 492                                 eclass = ExprClass.Value;
 493                         }
 494
 495                         public override Expression DoResolve (EmitContext ec)
 496                         {
 497                                 return this;
 498                         }
 499
 500                         public override void Emit (EmitContext ec)
 501                         {
 502                                 am.aec.EmitMethodHostInstance (ec, am);
 503                         }
 504                 }
 505         }
 506
 507         class CapturedParameter {
 508                 public Type Type;
 509                 public FieldBuilder FieldBuilder;
 510                 public int Idx;
 511
 512                 public CapturedParameter (Type type, int idx)
 513                 {
 514                         Type = type;
 515                         Idx = idx;
 516                 }
 517         }
 518
 519         //
 520         // Here we cluster all the variables captured on a given scope, we also
 521         // keep some extra information that might be required on each scope.
 522         //
 523         public class ScopeInfo {
 524                 public CaptureContext CaptureContext;
 525                 public ScopeInfo ParentScope;
 526                 public Block ScopeBlock;
 527                 public bool NeedThis = false;
 528                 public bool HostsParameters = false;
 529
 530                 // For tracking the number of scopes created.
 531                 public int id;
 532                 static int count;
 533                 bool inited = false;
 534
 535                 ArrayList locals = new ArrayList ();
 536                 ArrayList children = new ArrayList ();
 537
 538                 //
 539                 // The types and fields generated
 540                 //
 541                 public TypeBuilder ScopeTypeBuilder;
 542                 public ConstructorBuilder ScopeConstructor;
 543                 public FieldBuilder THIS;
 544                 public FieldBuilder ParentLink;
 545
 546                 //
 547                 // Points to the object of type `ScopeTypeBuilder' that
 548                 // holds the data for the scope
 549                 //
 550                 LocalBuilder scope_instance;
 551
 552                 public ScopeInfo (CaptureContext cc, Block b)
 553                 {
 554                         CaptureContext = cc;
 555                         ScopeBlock = b;
 556                         id = count++;
 557
 558                         cc.RegisterCaptureContext ();
 559                 }
 560
 561                 public void AddLocal (LocalInfo li)
 562                 {
 563                         if (locals.Contains (li))
 564                                 return;
 565
 566                         locals.Add (li);
 567                 }
 568
 569                 public bool IsCaptured (LocalInfo li)
 570                 {
 571                         return locals.Contains (li);
 572                 }
 573
 574                 internal void AddChild (ScopeInfo si)
 575                 {
 576                         if (children.Contains (si))
 577                                 return;
 578
 579                         //
 580                         // If any of the current children should be a children of `si', move them there
 581                         //
 582                         ArrayList move_queue = null;
 583                         foreach (ScopeInfo child in children){
 584                                 if (child.ScopeBlock.IsChildOf (si.ScopeBlock)){
 585                                         if (move_queue == null)
 586                                                 move_queue = new ArrayList ();
 587                                         move_queue.Add (child);
 588                                         child.ParentScope = si;
 589                                         si.AddChild (child);
 590                                 }
 591                         }
 592
 593                         children.Add (si);
 594
 595                         if (move_queue != null){
 596                                 foreach (ScopeInfo child in move_queue){
 597                                         children.Remove (child);
 598                                 }
 599                         }
 600                 }
 601
 602                 static int indent = 0;
 603
 604                 void Pad ()
 605                 {
 606                         for (int i = 0; i < indent; i++)
 607                                 Console.Write ("    ");
 608                 }
 609
 610                 void EmitDebug ()
 611                 {
 612                         //Console.WriteLine (Environment.StackTrace);
 613                         Pad ();
 614                         Console.WriteLine ("START");
 615                         indent++;
 616                         Pad ();
 617                         Console.WriteLine ("NeedThis=" + NeedThis);
 618                         foreach (LocalInfo li in locals){
 619                                 Pad ();
 620                                 Console.WriteLine ("var {0}", MakeFieldName (li.Name));
 621                         }
 622
 623                         foreach (ScopeInfo si in children)
 624                                 si.EmitDebug ();
 625                         indent--;
 626                         Pad ();
 627                         Console.WriteLine ("END");
 628                 }
 629
 630                 public string MakeHelperName ()
 631                 {
 632                         return String.Format ("<>AnonHelp<{0}>", id);
 633                 }
 634
 635                 private string MakeFieldName (string local_name)
 636                 {
 637                         return "<" + id + ":" + local_name + ">";
 638                 }
 639
 640                 public void EmitScopeType (EmitContext ec)
 641                 {
 642                         // EmitDebug ();
 643
 644                         if (ScopeTypeBuilder != null)
 645                                 return;
 646
 647                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 648
 649                         CaptureContext.Host.CreateScopeType (ec, this);
 650
 651                         if (NeedThis)
 652                                 THIS = ScopeTypeBuilder.DefineField ("<>THIS", container, FieldAttributes.Assembly);
 653
 654                         if (ParentScope != null){
 655                                 if (ParentScope.ScopeTypeBuilder == null){
 656                                         throw new Exception (String.Format ("My parent has not been initialized {0} and {1}", ParentScope, this));
 657                                 }
 658
 659                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder)
 660                                         ParentLink = ScopeTypeBuilder.DefineField ("<>parent", ParentScope.ScopeTypeBuilder,
 661                                                                                    FieldAttributes.Assembly);
 662                         }
 663
 664                         if (NeedThis && ParentScope != null)
 665                                 throw new Exception ("I was not expecting THIS && having a parent");
 666
 667                         foreach (LocalInfo info in locals)
 668                                 info.FieldBuilder = ScopeTypeBuilder.DefineField (
 669                                         MakeFieldName (info.Name), info.VariableType, FieldAttributes.Assembly);
 670
 671                         if (HostsParameters){
 672                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 673
 674                                 foreach (DictionaryEntry de in captured_parameters){
 675                                         string name = (string) de.Key;
 676                                         CapturedParameter cp = (CapturedParameter) de.Value;
 677                                         FieldBuilder fb;
 678
 679                                         fb = ScopeTypeBuilder.DefineField ("<p:" + name + ">", cp.Type, FieldAttributes.Assembly);
 680                                         cp.FieldBuilder = fb;
 681                                 }
 682                         }
 683
 684                         foreach (ScopeInfo si in children){
 685                                 si.EmitScopeType (ec);
 686                         }
 687                 }
 688
 689                 public void CloseTypes ()
 690                 {
 691                         RootContext.RegisterCompilerGeneratedType (ScopeTypeBuilder);
 692                         foreach (ScopeInfo si in children)
 693                                 si.CloseTypes ();
 694                 }
 695
 696                 //
 697                 // Emits the initialization code for the scope
 698                 //
 699                 public void EmitInitScope (EmitContext ec)
 700                 {
 701                         ILGenerator ig = ec.ig;
 702
 703                         if (inited)
 704                                 return;
 705
 706                         if (ScopeConstructor == null)
 707                                 throw new Exception ("ScopeConstructor is null for" + this.ToString ());
 708
 709                         if (!CaptureContext.Host.IsIterator) {
 710                                 scope_instance = ig.DeclareLocal (ScopeTypeBuilder);
 711                                 ig.Emit (OpCodes.Newobj, (ConstructorInfo) ScopeConstructor);
 712                                 ig.Emit (OpCodes.Stloc, scope_instance);
 713                         }
 714
 715                         if (THIS != null){
 716                                 if (CaptureContext.Host.IsIterator) {
 717                                         ig.Emit (OpCodes.Ldarg_0);
 718                                         ig.Emit (OpCodes.Ldarg_1);
 719                                 } else {
 720                                         ig.Emit (OpCodes.Ldloc, scope_instance);
 721                                         ig.Emit (OpCodes.Ldarg_0);
 722                                 }
 723                                 ig.Emit (OpCodes.Stfld, THIS);
 724                         }
 725
 726                         //
 727                         // Copy the parameter values, if any
 728                         //
 729                         int extra = ec.IsStatic ? 0 : 1;
 730                         if (CaptureContext.Host.IsIterator)
 731                                 extra++;
 732                         if (HostsParameters){
 733                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 734
 735                                 foreach (DictionaryEntry de in captured_parameters){
 736                                         CapturedParameter cp = (CapturedParameter) de.Value;
 737
 738                                         EmitScopeInstance (ig);
 739                                         ParameterReference.EmitLdArg (ig, cp.Idx + extra);
 740                                         ig.Emit (OpCodes.Stfld, cp.FieldBuilder);
 741                                 }
 742                         }
 743
 744                         if (ParentScope != null){
 745                                 if (!ParentScope.inited)
 746                                         ParentScope.EmitInitScope (ec);
 747
 748                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder) {
 749                                         //
 750                                         // Only emit initialization in our capturecontext world
 751                                         //
 752                                         if (ParentScope.CaptureContext == CaptureContext){
 753                                                 EmitScopeInstance (ig);
 754                                                 ParentScope.EmitScopeInstance (ig);
 755                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 756                                         } else {
 757                                                 EmitScopeInstance (ig);
 758                                                 ig.Emit (OpCodes.Ldarg_0);
 759                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 760                                         }
 761                                 }
 762                         }
 763                         inited = true;
 764                 }
 765
 766                 public void EmitScopeInstance (ILGenerator ig)
 767                 {
 768                         if (CaptureContext.Host.IsIterator)
 769                                 ig.Emit (OpCodes.Ldarg_0);
 770                         else
 771                                 ig.Emit (OpCodes.Ldloc, scope_instance);
 772                 }
 773
 774                 public static void CheckCycles (string msg, ScopeInfo s)
 775                 {
 776                         ArrayList l = new ArrayList ();
 777                         int n = 0;
 778
 779                         for (ScopeInfo p = s; p != null; p = p.ParentScope,n++){
 780                                 if (l.Contains (p)){
 781                                         Console.WriteLine ("Loop detected {0} in {1}", n, msg);
 782                                         throw new Exception ();
 783                                 }
 784                                 l.Add (p);
 785                         }
 786                 }
 787
 788                 static void DoPath (StringBuilder sb, ScopeInfo start)
 789                 {
 790                         CheckCycles ("print", start);
 791
 792                         if (start.ParentScope != null){
 793                                 DoPath (sb, start.ParentScope);
 794                                 sb.Append (", ");
 795                         }
 796                         sb.Append ((start.id).ToString ());
 797                 }
 798
 799                 public override string ToString ()
 800                 {
 801                         StringBuilder sb = new StringBuilder ();
 802
 803                         sb.Append ("{");
 804                         if (CaptureContext != null){
 805                                 sb.Append (CaptureContext.ToString ());
 806                                 sb.Append (":");
 807                         }
 808
 809                         DoPath (sb, this);
 810                         sb.Append ("}");
 811
 812                         return sb.ToString ();
 813                 }
 814         }
 815
 816         //
 817         // CaptureContext objects are created on demand if a method has
 818         // anonymous methods and kept on the ToplevelBlock.
 819         //
 820         // If they exist, all ToplevelBlocks in the containing block are
 821         // linked together (children pointing to their parents).
 822         //
 823         public class CaptureContext {
 824                 public static int count;
 825                 public int cc_id;
 826                 public Location loc;
 827
 828                 //
 829                 // Points to the toplevel block that owns this CaptureContext
 830                 //
 831                 ToplevelBlock toplevel_owner;
 832
 833                 //
 834                 // All the scopes we capture
 835                 //
 836                 Hashtable scopes = new Hashtable ();
 837
 838                 //
 839                 // All the root scopes
 840                 //
 841                 ArrayList roots = new ArrayList ();
 842
 843                 bool have_captured_vars = false;
 844                 bool referenced_this = false;
 845
 846                 //
 847                 // Captured fields
 848                 //
 849                 Hashtable captured_fields = new Hashtable ();
 850                 Hashtable captured_variables = new Hashtable ();
 851                 public Hashtable captured_parameters = new Hashtable ();
 852                 public AnonymousContainer Host;
 853
 854                 public CaptureContext (ToplevelBlock toplevel_owner, Location loc,
 855                                        AnonymousContainer host)
 856                 {
 857                         cc_id = count++;
 858                         this.toplevel_owner = toplevel_owner;
 859                         this.loc = loc;
 860
 861                         if (host != null)
 862                                 Host = host;
 863                 }
 864
 865                 void DoPath (StringBuilder sb, CaptureContext cc)
 866                 {
 867                         if (cc.ParentCaptureContext != null){
 868                                 DoPath (sb, cc.ParentCaptureContext);
 869                                 sb.Append (".");
 870                         }
 871                         sb.Append (cc.cc_id.ToString ());
 872                 }
 873
 874                 public void ReParent (ToplevelBlock new_toplevel, AnonymousContainer new_host)
 875                 {
 876                         toplevel_owner = new_toplevel;
 877                         Host = new_host;
 878
 879                         for (CaptureContext cc = ParentCaptureContext; cc != null;
 880                              cc = cc.ParentCaptureContext) {
 881                                 cc.Host = new_host;
 882                         }
 883                 }
 884
 885                 public override string ToString ()
 886                 {
 887                         StringBuilder sb = new StringBuilder ();
 888                         sb.Append ("[");
 889                         DoPath (sb, this);
 890                         sb.Append ("]");
 891                         return sb.ToString ();
 892                 }
 893
 894                 public ToplevelBlock ParentToplevel {
 895                         get {
 896                                 return toplevel_owner.Container;
 897                         }
 898                 }
 899
 900                 public CaptureContext ParentCaptureContext {
 901                         get {
 902                                 ToplevelBlock parent = ParentToplevel;
 903
 904                                 return (parent == null) ? null : parent.CaptureContext;
 905                         }
 906                 }
 907
 908                 ScopeInfo GetScopeForBlock (Block block)
 909                 {
 910                         ScopeInfo si = (ScopeInfo) scopes [block.ID];
 911                         if (si != null)
 912                                 return si;
 913                         si = new ScopeInfo (this, block);
 914                         scopes [block.ID] = si;
 915                         return si;
 916                 }
 917
 918                 public void AddLocal (AnonymousContainer am, LocalInfo li)
 919                 {
 920                         if (li.Block.Toplevel != toplevel_owner){
 921                                 ParentCaptureContext.AddLocal (am, li);
 922                                 return;
 923                         }
 924                         ScopeInfo scope = GetScopeForBlock (li.Block);
 925
 926                         //
 927                         // Adjust the owner
 928                         //
 929                         if (Host != null)
 930                                 Host.RegisterScope (scope);
 931
 932                         //
 933                         // Adjust the user
 934                         //
 935                         am.RegisterScope (scope);
 936
 937                         if (captured_variables [li] != null)
 938                                 return;
 939
 940                         have_captured_vars = true;
 941                         captured_variables [li] = li;
 942                         scope.AddLocal (li);
 943                 }
 944
 945                 //
 946                 // Retursn the CaptureContext for the block that defines the parameter `name'
 947                 //
 948                 static CaptureContext _ContextForParameter (ToplevelBlock current, string name)
 949                 {
 950                         ToplevelBlock container = current.Container;
 951                         if (container != null){
 952                                 CaptureContext cc = _ContextForParameter (container, name);
 953                                 if (cc != null)
 954                                         return cc;
 955                         }
 956                         if (current.IsParameterReference (name))
 957                                 return current.ToplevelBlockCaptureContext;
 958                         return null;
 959                 }
 960
 961                 static CaptureContext ContextForParameter (ToplevelBlock current, string name)
 962                 {
 963                         CaptureContext cc = _ContextForParameter (current, name);
 964                         if (cc == null)
 965                                 throw new Exception (String.Format ("request for parameteter {0} failed: not found", name));
 966                         return cc;
 967                 }
 968
 969                 //
 970                 // Records the captured parameter at the appropriate CaptureContext
 971                 //
 972                 public void AddParameter (EmitContext ec, AnonymousContainer am,
 973                                           string name, Type t, int idx)
 974                 {
 975                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
 976
 977                         cc.AddParameterToContext (am, name, t, idx);
 978                 }
 979
 980                 //
 981                 // Records the parameters in the context
 982                 //
 983                 public void AddParameterToContext (AnonymousContainer am, string name, Type t, int idx)
 984                 {
 985                         if (captured_parameters == null)
 986                                 captured_parameters = new Hashtable ();
 987                         if (captured_parameters [name] == null)
 988                                 captured_parameters [name] = new CapturedParameter (t, idx);
 989
 990                         ScopeInfo scope = GetScopeForBlock (toplevel_owner);
 991                         scope.HostsParameters = true;
 992                         am.RegisterScope (scope);
 993                 }
 994
 995                 //
 996                 // Captured fields are only recorded on the topmost CaptureContext, because that
 997                 // one is the one linked to the owner of instance fields
 998                 //
 999                 public void AddField (EmitContext ec, AnonymousContainer am, FieldExpr fe)
1000                 {
1001                         if (fe.FieldInfo.IsStatic)
1002                                 throw new Exception ("Attempt to register a static field as a captured field");
1003                         CaptureContext parent = ParentCaptureContext;
1004                         if (parent != null) {
1005                                 parent.AddField (ec, am, fe);
1006                                 return;
1007                         }
1008
1009                         ScopeInfo scope = GetScopeForBlock (toplevel_owner);
1010                         am.RegisterScope (scope);
1011                 }
1012
1013                 public void CaptureThis (AnonymousContainer am)
1014                 {
1015                         if (am == null)
1016                                 throw new Exception ("Internal Compiler error: Capturethis called with a null method");
1017                         CaptureContext parent = ParentCaptureContext;
1018                         if (parent != null) {
1019                                 parent.CaptureThis (am);
1020                                 return;
1021                         }
1022                         referenced_this = true;
1023
1024                         ScopeInfo scope = GetScopeForBlock (toplevel_owner);
1025                         am.RegisterScope (scope);
1026                 }
1027
1028                 public bool HaveCapturedVariables {
1029                         get {
1030                                 return have_captured_vars;
1031                         }
1032                 }
1033
1034                 public bool HaveCapturedFields {
1035                         get {
1036                                 CaptureContext parent = ParentCaptureContext;
1037                                 if (parent != null)
1038                                         return parent.HaveCapturedFields;
1039                                 return captured_fields.Count > 0;
1040                         }
1041                 }
1042
1043                 public bool IsCaptured (LocalInfo local)
1044                 {
1045                         foreach (ScopeInfo si in scopes.Values){
1046                                 if (si.IsCaptured (local))
1047                                         return true;
1048                         }
1049                         return false;
1050                 }
1051
1052                 //
1053                 // Returns whether the parameter is captured
1054                 //
1055                 public bool IsParameterCaptured (string name)
1056                 {
1057                         if (ParentCaptureContext != null && ParentCaptureContext.IsParameterCaptured (name))
1058                                 return true;
1059
1060                         if (captured_parameters != null)
1061                                 return captured_parameters [name] != null;
1062                         return false;
1063                 }
1064
1065                 public void EmitAnonymousHelperClasses (EmitContext ec)
1066                 {
1067                         if (roots.Count != 0){
1068                                 foreach (ScopeInfo root in roots){
1069                                         //
1070                                         // FIXME: We really should do this in a per-ScopeInfo
1071                                         // basis, instead of having the NeedThis applied to
1072                                         // all of the roots.
1073                                         //
1074                                         root.NeedThis = HaveCapturedFields || referenced_this;
1075
1076                                         root.EmitScopeType (ec);
1077                                 }
1078                         }
1079                 }
1080
1081                 public void CloseAnonymousHelperClasses ()
1082                 {
1083                         if (roots.Count != 0)
1084                                 foreach (ScopeInfo root in roots)
1085                                         root.CloseTypes ();
1086                 }
1087
1088                 public void EmitInitScope (EmitContext ec)
1089                 {
1090                         EmitAnonymousHelperClasses (ec);
1091                         if (roots.Count != 0)
1092                                 foreach (ScopeInfo root in roots)
1093                                         root.EmitInitScope (ec);
1094                 }
1095
1096                 ScopeInfo EmitGetScopeFromBlock (EmitContext ec, Block b)
1097                 {
1098                         ScopeInfo si;
1099
1100                         si = (ScopeInfo) scopes [b.ID];
1101                         if (si == null)
1102                                 throw new Exception ("Si is null for block " + b.ID);
1103                         si.EmitInitScope (ec);
1104
1105                         return si;
1106                 }
1107
1108                 //
1109                 // Emits the opcodes necessary to load the instance of the captured
1110                 // variable in `li'
1111                 //
1112                 public void EmitCapturedVariableInstance (EmitContext ec, LocalInfo li,
1113                                                           AnonymousContainer am)
1114                 {
1115                         ILGenerator ig = ec.ig;
1116                         ScopeInfo si;
1117
1118                         if (li.Block.Toplevel == toplevel_owner){
1119                                 si = EmitGetScopeFromBlock (ec, li.Block);
1120                                 si.EmitScopeInstance (ig);
1121                                 return;
1122                         }
1123
1124                         si = am.Scope;
1125                         ig.Emit (OpCodes.Ldarg_0);
1126                         if (si != null){
1127                                 if (am.IsIterator && (si.ScopeBlock.Toplevel == li.Block.Toplevel)) {
1128                                         return;
1129                                 }
1130
1131                                 while (si.ScopeBlock.ID != li.Block.ID){
1132                                         if (si.ParentLink != null)
1133                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
1134                                         si = si.ParentScope;
1135                                         if (si == null) {
1136                                                 si = am.Scope;
1137                                                 Console.WriteLine ("Target: {0} {1}", li.Block.ID, li.Name);
1138                                                 while (si.ScopeBlock.ID != li.Block.ID){
1139                                                         Console.WriteLine ("Trying: {0}", si.ScopeBlock.ID);
1140                                                         si = si.ParentScope;
1141                                                 }
1142
1143                                                 throw new Exception (
1144                                                              String.Format ("Never found block {0} starting at {1} while looking up {2}",
1145                                                                             li.Block.ID, am.Scope.ScopeBlock.ID, li.Name));
1146                                         }
1147                                 }
1148                         }
1149                 }
1150
1151                 //
1152                 // Internal routine that loads the instance to reach parameter `name'
1153                 //
1154                 void EmitParameterInstance (EmitContext ec, string name)
1155                 {
1156                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1157                         if (cc != this){
1158                                 cc.EmitParameterInstance (ec, name);
1159                                 return;
1160                         }
1161
1162                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1163                         if (par_info != null){
1164                                 //
1165                                 // FIXME: implementing this.
1166                                 //
1167                         }
1168                         ILGenerator ig = ec.ig;
1169
1170                         ScopeInfo si;
1171
1172                         if (ec.CurrentBlock.Toplevel == toplevel_owner) {
1173                                 si = EmitGetScopeFromBlock (ec, toplevel_owner);
1174                                 si.EmitScopeInstance (ig);
1175                         } else {
1176                                 si = ec.CurrentAnonymousMethod.Scope;
1177                                 ig.Emit (OpCodes.Ldarg_0);
1178                         }
1179
1180                         if (si != null){
1181                                 while (si.ParentLink != null) {
1182                                         ig.Emit (OpCodes.Ldfld, si.ParentLink);
1183                                         si = si.ParentScope;
1184                                 }
1185                         }
1186                 }
1187
1188                 //
1189                 // Emits the code necessary to load the parameter named `name' within
1190                 // an anonymous method.
1191                 //
1192                 public void EmitParameter (EmitContext ec, string name, bool leave_copy, bool prepared, ref LocalTemporary temp)
1193                 {
1194                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1195                         if (cc != this){
1196                                 cc.EmitParameter (ec, name, leave_copy, prepared, ref temp);
1197                                 return;
1198                         }
1199                         if (!prepared)
1200                                 EmitParameterInstance (ec, name);
1201                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1202                         if (par_info != null){
1203                                 //
1204                                 // FIXME: implementing this.
1205                                 //
1206                         }
1207                         ec.ig.Emit (OpCodes.Ldfld, par_info.FieldBuilder);
1208
1209                         if (leave_copy){
1210                                 ec.ig.Emit (OpCodes.Dup);
1211                                 temp = new LocalTemporary (ec, par_info.FieldBuilder.FieldType);
1212                                 temp.Store (ec);
1213                         }
1214                 }
1215
1216                 //
1217                 // Implements the assignment of `source' to the paramenter named `name' within
1218                 // an anonymous method.
1219                 //
1220                 public void EmitAssignParameter (EmitContext ec, string name, Expression source, bool leave_copy, bool prepare_for_load, ref LocalTemporary temp)
1221                 {
1222                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1223                         if (cc != this){
1224                                 cc.EmitAssignParameter (ec, name, source, leave_copy, prepare_for_load, ref temp);
1225                                 return;
1226                         }
1227                         ILGenerator ig = ec.ig;
1228                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1229
1230                         EmitParameterInstance (ec, name);
1231                         if (prepare_for_load)
1232                                 ig.Emit (OpCodes.Dup);
1233                         source.Emit (ec);
1234                         if (leave_copy){
1235                                 ig.Emit (OpCodes.Dup);
1236                                 temp = new LocalTemporary (ec, par_info.FieldBuilder.FieldType);
1237                                 temp.Store (ec);
1238                         }
1239                         ig.Emit (OpCodes.Stfld, par_info.FieldBuilder);
1240                         if (temp != null)
1241                                 temp.Emit (ec);
1242                 }
1243
1244                 //
1245                 // Emits the address for the parameter named `name' within
1246                 // an anonymous method.
1247                 //
1248                 public void EmitAddressOfParameter (EmitContext ec, string name)
1249                 {
1250                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1251                         if (cc != this){
1252                                 cc.EmitAddressOfParameter (ec, name);
1253                                 return;
1254                         }
1255                         EmitParameterInstance (ec, name);
1256                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1257                         ec.ig.Emit (OpCodes.Ldflda, par_info.FieldBuilder);
1258                 }
1259
1260                 //
1261                 // The following methods are only invoked on the host for the
1262                 // anonymous method.
1263                 //
1264                 public void EmitMethodHostInstance (EmitContext target, AnonymousContainer am)
1265                 {
1266                         ILGenerator ig = target.ig;
1267                         ScopeInfo si = am.Scope;
1268
1269                         AnonymousContainer container = am.ContainerAnonymousMethod;
1270
1271                         if ((si == null) || ((container != null) && (si == container.Scope))) {
1272                                 ig.Emit (OpCodes.Ldarg_0);
1273                                 return;
1274                         }
1275
1276                         si.EmitInitScope (target);
1277                         si.EmitScopeInstance (ig);
1278                 }
1279
1280                 public void RegisterCaptureContext ()
1281                 {
1282                         toplevel_owner.RegisterCaptureContext (this);
1283                 }
1284
1285                 //
1286                 // Returs true if `probe' is an ancestor of `scope' in the
1287                 // scope chain
1288                 //
1289                 bool IsAncestor (ScopeInfo probe, ScopeInfo scope)
1290                 {
1291                         for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
1292                                 if (probe.ScopeBlock == b)
1293                                         return true;
1294                         }
1295                         return false;
1296                 }
1297
1298                 //
1299                 // Returns an ArrayList of ScopeInfos that enumerates all the ancestors
1300                 // of `scope' found in `scope_list'.
1301                 //
1302                 // The value returned is either a ScopeInfo or an Arraylist of ScopeInfos
1303                 //
1304                 object GetAncestorScopes (ScopeInfo scope, ScopeInfo [] scope_list)
1305                 {
1306                         object ancestors = null;
1307
1308                         for (int i = 0; i < scope_list.Length; i++){
1309                                 // Ignore the same scope
1310                                 if (scope_list [i] == scope)
1311                                         continue;
1312
1313                                 if (IsAncestor (scope_list [i], scope)){
1314                                         if (ancestors == null){
1315                                                 ancestors = scope_list [i];
1316                                                 continue;
1317                                         }
1318
1319                                         if (ancestors is ScopeInfo){
1320                                                 object old = ancestors;
1321                                                 ancestors = new ArrayList (4);
1322                                                 ((ArrayList)ancestors).Add (old);
1323                                         }
1324
1325                                         ((ArrayList)ancestors).Add (scope_list [i]);
1326                                 }
1327                         }
1328                         return ancestors;
1329                 }
1330
1331                 //
1332                 // Returns the immediate parent of `scope' from all the captured
1333                 // scopes found in `scope_list', or null if this is a toplevel scope.
1334                 //
1335                 ScopeInfo GetParentScope (ScopeInfo scope, ScopeInfo [] scope_list)
1336                 {
1337                         object ancestors = GetAncestorScopes (scope, scope_list);
1338                         if (ancestors == null)
1339                                 return null;
1340
1341                         // Single match, thats the parent.
1342                         if (ancestors is ScopeInfo)
1343                                 return (ScopeInfo) ancestors;
1344
1345                         ArrayList candidates = (ArrayList) ancestors;
1346                         ScopeInfo parent = (ScopeInfo) candidates [0];
1347                         for (int i = 1; i < candidates.Count; i++){
1348                                 if (IsAncestor (parent, (ScopeInfo) candidates [i]))
1349                                         parent = (ScopeInfo) candidates [i];
1350                         }
1351                         return parent;
1352                 }
1353
1354                 //
1355                 // Links all the scopes
1356                 //
1357                 bool linked;
1358                 public void LinkScopes ()
1359                 {
1360                         if (linked)
1361                                 return;
1362
1363                         linked = true;
1364                         if (ParentCaptureContext != null)
1365                                 ParentCaptureContext.LinkScopes ();
1366
1367                         int scope_count = scopes.Keys.Count;
1368                         ScopeInfo [] scope_list = new ScopeInfo [scope_count];
1369                         scopes.Values.CopyTo (scope_list, 0);
1370
1371                         for (int i = 0; i < scope_count; i++){
1372                                 ScopeInfo parent = GetParentScope (scope_list [i], scope_list);
1373
1374                                 if (parent == null){
1375                                         roots.Add (scope_list [i]);
1376                                         continue;
1377                                 }
1378
1379                                 scope_list [i].ParentScope = parent;
1380                                 parent.AddChild (scope_list [i]);
1381                         }
1382
1383                         //
1384                         // Link the roots to their parent containers if any.
1385                         //
1386                         if (ParentCaptureContext != null && roots.Count != 0){
1387                                 ScopeInfo one_root = (ScopeInfo) roots [0];
1388                                 bool found = false;
1389
1390                                 foreach (ScopeInfo a_parent_root in ParentCaptureContext.roots){
1391                                         if (!IsAncestor (a_parent_root, one_root))
1392                                                 continue;
1393
1394                                         found = true;
1395
1396                                         // Found, link all the roots to this root
1397                                         foreach (ScopeInfo root in roots){
1398                                                 root.ParentScope = a_parent_root;
1399                                                 a_parent_root.AddChild (root);
1400                                         }
1401                                         break;
1402                                 }
1403                                 if (!found){
1404                                         //
1405                                         // This is to catch a condition in which it is
1406                                         // not possible to determine the containing ScopeInfo
1407                                         // from an encapsulating CaptureContext
1408                                         //
1409                                         throw new Exception ("Internal compiler error: Did not find the parent for the root in the chain");
1410                                 }
1411                         }
1412                 }
1413         }
1414 }