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