mcs/mcs/anonymous.cs

   1 //
   2 // anonymous.cs: Support for anonymous methods
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximain.com)
   6 //
   7 // (C) 2003, 2004 Novell, Inc.
   8 //
   9 // TODO: Ideally, we should have the helper classes emited as a hierarchy to map
  10 // their nesting, and have the visibility set to private, instead of NestedAssembly
  11 //
  12 //
  13 //
  14
  15 using System;
  16 using System.Text;
  17 using System.Collections;
  18 using System.Reflection;
  19 using System.Reflection.Emit;
  20
  21 namespace Mono.CSharp {
  22
  23         public abstract class AnonymousContainer : Expression
  24         {
  25                 // Used to generate unique method names.
  26                 protected static int anonymous_method_count;
  27
  28                 // An array list of AnonymousMethodParameter or null
  29                 public Parameters Parameters;
  30
  31                 //
  32                 // The block that makes up the body for the anonymous mehtod
  33                 //
  34                 public ToplevelBlock Block;
  35
  36                 //
  37                 // The container block for this anonymous method.
  38                 //
  39                 public Block ContainingBlock;
  40
  41                 //
  42                 // The implicit method we create
  43                 //
  44                 public Method method;
  45
  46                 protected MethodInfo invoke_mb;
  47
  48                 // The emit context for the anonymous method
  49                 public EmitContext aec;
  50                 public InternalParameters amp;
  51                 protected bool unreachable;
  52
  53                 //
  54                 // The modifiers applied to the method, we aggregate them
  55                 //
  56                 protected int method_modifiers = Modifiers.PRIVATE;
  57
  58                 //
  59                 // During the resolve stage of the anonymous method body,
  60                 // we discover the actual scope where we are hosted, or
  61                 // null to host the method in the same class
  62                 //
  63                 public ScopeInfo Scope;
  64
  65                 //
  66                 // Points to our container anonymous method if its present
  67                 //
  68                 public AnonymousContainer ContainerAnonymousMethod;
  69
  70                 protected AnonymousContainer (Parameters parameters, ToplevelBlock container,
  71                                               ToplevelBlock block, Location l)
  72                 {
  73                         Parameters = parameters;
  74                         Block = block;
  75                         loc = l;
  76
  77                         //
  78                         // The order is important: this setups the CaptureContext tree hierarchy.
  79                         //
  80                         container.SetHaveAnonymousMethods (l, this);
  81                         block.SetHaveAnonymousMethods (l, this);
  82                 }
  83
  84                 protected AnonymousContainer (Parameters parameters, ToplevelBlock container,
  85                                               Location l)
  86                 {
  87                         Parameters = parameters;
  88                         Block = new ToplevelBlock (container, Parameters, l);
  89                         loc = l;
  90
  91                         //
  92                         // The order is important: this setups the CaptureContext tree hierarchy.
  93                         //
  94                         container.SetHaveAnonymousMethods (loc, this);
  95                         Block.SetHaveAnonymousMethods (loc, this);
  96                 }
  97
  98                 public override Expression DoResolve (EmitContext ec)
  99                 {
 100                         //
 101                         // Set class type, set type
 102                         //
 103
 104                         eclass = ExprClass.Value;
 105
 106                         //
 107                         // This hack means `The type is not accessible
 108                         // anywhere', we depend on special conversion
 109                         // rules.
 110                         //
 111                         type = TypeManager.anonymous_method_type;
 112
 113                         return this;
 114                 }
 115
 116                 protected abstract bool CreateMethodHost (EmitContext ec);
 117
 118                 public abstract void CreateScopeType (EmitContext ec, ScopeInfo scope);
 119
 120                 public abstract bool IsIterator {
 121                         get;
 122                 }
 123         }
 124
 125         public class AnonymousMethod : AnonymousContainer
 126         {
 127                 public AnonymousMethod (Parameters parameters, ToplevelBlock container,
 128                                         ToplevelBlock block, Location l)
 129                         : base (parameters, container, block, l)
 130                 {
 131                 }
 132
 133                 public override bool IsIterator {
 134                         get { return false; }
 135                 }
 136
 137                 public override void Emit (EmitContext ec)
 138                 {
 139                         // nothing, as we only exist to not do anything.
 140                 }
 141
 142                 //
 143                 // Creates the host for the anonymous method
 144                 //
 145                 protected override bool CreateMethodHost (EmitContext ec)
 146                 {
 147                         //
 148                         // Crude hack follows: we replace the TypeBuilder during the
 149                         // definition to get the method hosted in the right class
 150                         //
 151
 152                         TypeBuilder current_type = ec.TypeContainer.TypeBuilder;
 153                         TypeBuilder type_host = (Scope == null ) // || Scope.ScopeTypeBuilder == null)
 154                                 ? current_type : Scope.ScopeTypeBuilder;
 155
 156                         if (current_type == null)
 157                                 throw new Exception ("The current_type is null");
 158
 159                         if (type_host == null)
 160                                 throw new Exception (String.Format ("Type host is null, Scope is {0}", Scope == null ? "null" : "Not null"));
 161
 162                         if (current_type == type_host && ec.IsStatic){
 163                                 if (ec.IsStatic){
 164                                         method_modifiers |= Modifiers.STATIC;
 165                                 }
 166                                 current_type = null;
 167                         }
 168
 169                         method = new Method (
 170                                 (TypeContainer) ec.TypeContainer,
 171                                 new TypeExpression (invoke_mb.ReturnType, loc),
 172                                 method_modifiers, false, new MemberName ("<#AnonymousMethod>" + anonymous_method_count++),
 173                                 Parameters, null, loc);
 174                         method.Block = Block;
 175
 176                         //
 177                         // Swap the TypeBuilder while we define the method, then restore
 178                         //
 179                         if (current_type != null)
 180                                 ec.TypeContainer.TypeBuilder = type_host;
 181                         bool res = method.Define ();
 182                         if (current_type != null)
 183                                 ec.TypeContainer.TypeBuilder = current_type;
 184                         return res;
 185                 }
 186
 187                 void Error_ParameterMismatch (Type t)
 188                 {
 189                         Report.Error (1661, loc, "Anonymous method could not be converted to delegate `" +
 190                                       "{0}' since there is a parameter mismatch", t);
 191                 }
 192
 193                 //
 194                 // Returns true if this anonymous method can be implicitly
 195                 // converted to the delegate type `delegate_type'
 196                 //
 197                 public Expression Compatible (EmitContext ec, Type delegate_type, bool probe)
 198                 {
 199                         //
 200                         // At this point its the first time we know the return type that is
 201                         // needed for the anonymous method.  We create the method here.
 202                         //
 203
 204                         invoke_mb = (MethodInfo) Delegate.GetInvokeMethod (ec, delegate_type, loc);
 205                         ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
 206
 207                         if (Parameters == null){
 208                                 int i, j;
 209
 210                                 //
 211                                 // We provide a set of inaccessible parameters
 212                                 //
 213                                 int params_idx = -1;
 214                                 for (i = 0; i < invoke_pd.Count; i++){
 215                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 216                                                 params_idx = i;
 217                                 }
 218                                 int n = invoke_pd.Count - (params_idx != -1 ? 1 : 0);
 219                                 Parameter [] fixedpars = new Parameter [n];
 220
 221                                 for (i =  j = 0; i < invoke_pd.Count; i++){
 222                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 223                                                 continue;
 224                                         fixedpars [j] = new Parameter (
 225                                                 new TypeExpression (invoke_pd.ParameterType (i), loc),
 226                                                 "+" + j, invoke_pd.ParameterModifier (i), null, loc);
 227                                         j++;
 228                                 }
 229
 230                                 Parameter variable = null;
 231                                 if (params_idx != -1){
 232                                         variable = new Parameter (
 233                                                 new TypeExpression (invoke_pd.ParameterType (params_idx), loc),
 234                                                 "+" + params_idx, invoke_pd.ParameterModifier (params_idx), null, loc);
 235                                 }
 236
 237                                 Parameters = new Parameters (fixedpars, variable);
 238                         }
 239
 240                         //
 241                         // First, parameter types of `delegate_type' must be compatible
 242                         // with the anonymous method.
 243                         //
 244                         amp = new InternalParameters (Parameters.GetParameterInfo (ec), Parameters);
 245
 246                         if (amp.Count != invoke_pd.Count){
 247                                 if (!probe){
 248                                         Report.Error (1593, loc, "Delegate `{0}' does not take `{1}' arguments",
 249                                                 TypeManager.CSharpName (delegate_type), amp.Count);
 250                                         Error_ParameterMismatch (delegate_type);
 251                                 }
 252                                 return null;
 253                         }
 254
 255                         for (int i = 0; i < amp.Count; i++){
 256                                 Parameter.Modifier amp_mod = amp.ParameterModifier (i);
 257
 258                                 if (!probe) {
 259                                         if ((amp_mod & (Parameter.Modifier.OUT | Parameter.Modifier.REF)) != 0){
 260                                                 Report.Error (1677, loc, "Parameter `{0}' should not be declared with the `{1}' keyword",
 261                                                         i+1, amp.ModifierDesc (i));
 262                                                 Error_ParameterMismatch (delegate_type);
 263                                                 return null;
 264                                         }
 265
 266                                         if (amp_mod != invoke_pd.ParameterModifier (i)){
 267                                                 Report.Error (1676, loc, "Parameter `{0}' must be declared with the `{1}' keyword",
 268                                                         i+1, Parameter.GetModifierSignature (invoke_pd.ParameterModifier (i)));
 269                                                 Error_ParameterMismatch (delegate_type);
 270                                                 return null;
 271                                         }
 272
 273                                         if (amp.ParameterType (i) != invoke_pd.ParameterType (i)){
 274                                                 Report.Error (1678, loc, "Parameter `{0}' is declared as type `{1}' but should be `{2}'",
 275                                                         i+1,
 276                                                         TypeManager.CSharpName (amp.ParameterType (i)),
 277                                                         TypeManager.CSharpName (invoke_pd.ParameterType (i)));
 278                                                 Error_ParameterMismatch (delegate_type);
 279                                                 return null;
 280                                         }
 281                                 }
 282                         }
 283
 284                         //
 285                         // If we are only probing, return ourselves
 286                         //
 287                         if (probe)
 288                                 return this;
 289
 290                         //
 291                         // Second: the return type of the delegate must be compatible with
 292                         // the anonymous type.   Instead of doing a pass to examine the block
 293                         // we satisfy the rule by setting the return type on the EmitContext
 294                         // to be the delegate type return type.
 295                         //
 296
 297                         //MethodBuilder builder = method_data.MethodBuilder;
 298                         //ILGenerator ig = builder.GetILGenerator ();
 299
 300
 301                         aec = new EmitContext (
 302                                 ec.TypeContainer, ec.DeclSpace, loc, null,
 303                                 invoke_mb.ReturnType,
 304                                 /* REVIEW */ (ec.InIterator ? Modifiers.METHOD_YIELDS : 0) |
 305                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0) |
 306                                 (ec.IsStatic ? Modifiers.STATIC : 0),
 307                                 /* No constructor */ false);
 308
 309                         aec.CurrentAnonymousMethod = this;
 310                         ContainerAnonymousMethod = ec.CurrentAnonymousMethod;
 311                         ContainingBlock = ec.CurrentBlock;
 312
 313                         if (aec.ResolveTopBlock (ec, Block, amp, null, out unreachable))
 314                                 return new AnonymousDelegate (this, delegate_type, loc).Resolve (ec);
 315
 316                         return null;
 317                 }
 318
 319                 public MethodBuilder GetMethodBuilder ()
 320                 {
 321                         return method.MethodData.MethodBuilder;
 322                 }
 323
 324                 public override string GetSignatureForError ()
 325                 {
 326                         string s = TypeManager.CSharpSignature (invoke_mb);
 327                         return s.Substring (0, s.IndexOf (".Invoke("));
 328                 }
 329
 330                 public bool EmitMethod (EmitContext ec)
 331                 {
 332                         if (!CreateMethodHost (ec))
 333                                 return false;
 334
 335                         MethodBuilder builder = GetMethodBuilder ();
 336                         ILGenerator ig = builder.GetILGenerator ();
 337                         aec.ig = ig;
 338
 339                         Parameters.LabelParameters (aec, builder);
 340
 341                         //
 342                         // Adjust based on the computed state of the
 343                         // method from CreateMethodHost
 344
 345                         aec.MethodIsStatic = (method_modifiers & Modifiers.STATIC) != 0;
 346
 347                         aec.EmitMeta (Block, amp);
 348                         aec.EmitResolvedTopBlock (Block, unreachable);
 349                         return true;
 350                 }
 351
 352                 public override void CreateScopeType (EmitContext ec, ScopeInfo scope)
 353                 {
 354                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 355                         string name = String.Format ("<>AnonHelp<{0}>", scope.id);
 356
 357                         scope.ScopeTypeBuilder = container.DefineNestedType (
 358                                 name, TypeAttributes.AutoLayout | TypeAttributes.Class |
 359                                 TypeAttributes.NestedAssembly, TypeManager.object_type, null);
 360
 361                         Type [] constructor_types = TypeManager.NoTypes;
 362                         Parameters constructor_parameters = Parameters.EmptyReadOnlyParameters;
 363                         scope.ScopeConstructor = scope.ScopeTypeBuilder.DefineConstructor (
 364                                 MethodAttributes.Public | MethodAttributes.HideBySig |
 365                                 MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
 366                                 CallingConventions.HasThis, constructor_types);
 367                         InternalParameters parameter_info = new InternalParameters (constructor_types, constructor_parameters);
 368                         TypeManager.RegisterMethod (scope.ScopeConstructor, parameter_info, constructor_types);
 369
 370                         ILGenerator cig = scope.ScopeConstructor.GetILGenerator ();
 371                         cig.Emit (OpCodes.Ldarg_0);
 372                         cig.Emit (OpCodes.Call, TypeManager.object_ctor);
 373                         cig.Emit (OpCodes.Ret);
 374                 }
 375
 376                 public static void Error_AddressOfCapturedVar (string name, Location loc)
 377                 {
 378                         Report.Error (1686, loc,
 379                                 "Local variable `{0}' or its members cannot have their address taken and be used inside an anonymous method block",
 380                                 name);
 381                 }
 382         }
 383
 384         //
 385         // This will emit the code for the delegate, as well delegate creation on the host
 386         //
 387         public class AnonymousDelegate : DelegateCreation {
 388                 AnonymousMethod am;
 389
 390                 public AnonymousDelegate (AnonymousMethod am, Type target_type, Location l)
 391                 {
 392                         type = target_type;
 393                         loc = l;
 394                         this.am = am;
 395                 }
 396
 397                 public override Expression DoResolve (EmitContext ec)
 398                 {
 399                         eclass = ExprClass.Value;
 400
 401                         return this;
 402                 }
 403
 404                 public override void Emit (EmitContext ec)
 405                 {
 406                         if (!am.EmitMethod (ec))
 407                                 return;
 408
 409                         //
 410                         // Now emit the delegate creation.
 411                         //
 412                         if ((am.method.ModFlags & Modifiers.STATIC) == 0)
 413                                 delegate_instance_expression = new AnonymousInstance (am);
 414
 415                         Expression ml = Expression.MemberLookup (ec, type, ".ctor", loc);
 416                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 417                         delegate_method = am.GetMethodBuilder ();
 418                         base.Emit (ec);
 419                 }
 420
 421                 class AnonymousInstance : Expression {
 422                         AnonymousMethod am;
 423
 424                         public AnonymousInstance (AnonymousMethod am)
 425                         {
 426                                 this.am = am;
 427                                 eclass = ExprClass.Value;
 428                         }
 429
 430                         public override Expression DoResolve (EmitContext ec)
 431                         {
 432                                 return this;
 433                         }
 434
 435                         public override void Emit (EmitContext ec)
 436                         {
 437                                 am.aec.EmitMethodHostInstance (ec, am);
 438                         }
 439                 }
 440         }
 441
 442         class CapturedParameter {
 443                 public Type Type;
 444                 public FieldBuilder FieldBuilder;
 445                 public int Idx;
 446
 447                 public CapturedParameter (Type type, int idx)
 448                 {
 449                         Type = type;
 450                         Idx = idx;
 451                 }
 452         }
 453
 454         //
 455         // Here we cluster all the variables captured on a given scope, we also
 456         // keep some extra information that might be required on each scope.
 457         //
 458         public class ScopeInfo {
 459                 public CaptureContext CaptureContext;
 460                 public ScopeInfo ParentScope;
 461                 public Block ScopeBlock;
 462                 public bool NeedThis = false;
 463                 public bool HostsParameters = false;
 464
 465                 // For tracking the number of scopes created.
 466                 public int id;
 467                 static int count;
 468                 bool inited = false;
 469
 470                 ArrayList locals = new ArrayList ();
 471                 ArrayList children = new ArrayList ();
 472
 473                 //
 474                 // The types and fields generated
 475                 //
 476                 public TypeBuilder ScopeTypeBuilder;
 477                 public ConstructorBuilder ScopeConstructor;
 478                 public FieldBuilder THIS;
 479                 public FieldBuilder ParentLink;
 480
 481                 //
 482                 // Points to the object of type `ScopeTypeBuilder' that
 483                 // holds the data for the scope
 484                 //
 485                 LocalBuilder scope_instance;
 486
 487                 public ScopeInfo (CaptureContext cc, Block b)
 488                 {
 489                         CaptureContext = cc;
 490                         ScopeBlock = b;
 491                         id = count++;
 492
 493                         cc.AddScope (this);
 494                 }
 495
 496                 public void AddLocal (LocalInfo li)
 497                 {
 498                         if (locals.Contains (li))
 499                                 return;
 500
 501                         locals.Add (li);
 502                 }
 503
 504                 public bool IsCaptured (LocalInfo li)
 505                 {
 506                         return locals.Contains (li);
 507                 }
 508
 509                 internal void AddChild (ScopeInfo si)
 510                 {
 511                         if (children.Contains (si))
 512                                 return;
 513
 514                         //
 515                         // If any of the current children should be a children of `si', move them there
 516                         //
 517                         ArrayList move_queue = null;
 518                         foreach (ScopeInfo child in children){
 519                                 if (child.ScopeBlock.IsChildOf (si.ScopeBlock)){
 520                                         if (move_queue == null)
 521                                                 move_queue = new ArrayList ();
 522                                         move_queue.Add (child);
 523                                         child.ParentScope = si;
 524                                         si.AddChild (child);
 525                                 }
 526                         }
 527
 528                         children.Add (si);
 529
 530                         if (move_queue != null){
 531                                 foreach (ScopeInfo child in move_queue){
 532                                         children.Remove (child);
 533                                 }
 534                         }
 535                 }
 536
 537                 static int indent = 0;
 538
 539                 void Pad ()
 540                 {
 541                         for (int i = 0; i < indent; i++)
 542                                 Console.Write ("    ");
 543                 }
 544
 545                 void EmitDebug ()
 546                 {
 547                         //Console.WriteLine (Environment.StackTrace);
 548                         Pad ();
 549                         Console.WriteLine ("START");
 550                         indent++;
 551                         Pad ();
 552                         Console.WriteLine ("NeedThis=" + NeedThis);
 553                         foreach (LocalInfo li in locals){
 554                                 Pad ();
 555                                 Console.WriteLine ("var {0}", li.Name);
 556                         }
 557
 558                         foreach (ScopeInfo si in children)
 559                                 si.EmitDebug ();
 560                         indent--;
 561                         Pad ();
 562                         Console.WriteLine ("END");
 563                 }
 564
 565                 public string MakeHelperName ()
 566                 {
 567                         return String.Format ("<>AnonHelp<{0}>", id);
 568                 }
 569
 570                 public void EmitScopeType (EmitContext ec)
 571                 {
 572                         // EmitDebug ();
 573
 574                         if (ScopeTypeBuilder != null)
 575                                 return;
 576
 577                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 578
 579                         CaptureContext.Host.CreateScopeType (ec, this);
 580
 581                         if (NeedThis)
 582                                 THIS = ScopeTypeBuilder.DefineField ("<>THIS", container, FieldAttributes.Assembly);
 583
 584                         if (ParentScope != null){
 585                                 if (ParentScope.ScopeTypeBuilder == null){
 586                                         throw new Exception (String.Format ("My parent has not been initialized {0} and {1}", ParentScope, this));
 587                                 }
 588
 589                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder)
 590                                         ParentLink = ScopeTypeBuilder.DefineField ("<>parent", ParentScope.ScopeTypeBuilder,
 591                                                                                    FieldAttributes.Assembly);
 592                         }
 593
 594                         if (NeedThis && ParentScope != null)
 595                                 throw new Exception ("I was not expecting THIS && having a parent");
 596
 597                         foreach (LocalInfo info in locals)
 598                                 info.FieldBuilder = ScopeTypeBuilder.DefineField (
 599                                         info.Name, info.VariableType, FieldAttributes.Assembly);
 600
 601                         if (HostsParameters){
 602                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 603
 604                                 foreach (DictionaryEntry de in captured_parameters){
 605                                         string name = (string) de.Key;
 606                                         CapturedParameter cp = (CapturedParameter) de.Value;
 607                                         FieldBuilder fb;
 608
 609                                         fb = ScopeTypeBuilder.DefineField ("<p:" + name + ">", cp.Type, FieldAttributes.Assembly);
 610                                         cp.FieldBuilder = fb;
 611                                 }
 612                         }
 613
 614                         foreach (ScopeInfo si in children){
 615                                 si.EmitScopeType (ec);
 616                         }
 617                 }
 618
 619                 public void CloseTypes ()
 620                 {
 621                         RootContext.RegisterCompilerGeneratedType (ScopeTypeBuilder);
 622                         foreach (ScopeInfo si in children)
 623                                 si.CloseTypes ();
 624                 }
 625
 626                 //
 627                 // Emits the initialization code for the scope
 628                 //
 629                 public void EmitInitScope (EmitContext ec)
 630                 {
 631                         ILGenerator ig = ec.ig;
 632
 633                         if (inited)
 634                                 return;
 635
 636                         if (ScopeConstructor == null)
 637                                 throw new Exception ("ScopeConstructor is null for" + this.ToString ());
 638
 639                         if (!CaptureContext.Host.IsIterator) {
 640                                 scope_instance = ig.DeclareLocal (ScopeTypeBuilder);
 641                                 ig.Emit (OpCodes.Newobj, (ConstructorInfo) ScopeConstructor);
 642                                 ig.Emit (OpCodes.Stloc, scope_instance);
 643                         }
 644
 645                         if (THIS != null){
 646                                 if (CaptureContext.Host.IsIterator) {
 647                                         ig.Emit (OpCodes.Ldarg_0);
 648                                         ig.Emit (OpCodes.Ldarg_1);
 649                                 } else {
 650                                         ig.Emit (OpCodes.Ldloc, scope_instance);
 651                                         ig.Emit (OpCodes.Ldarg_0);
 652                                 }
 653                                 ig.Emit (OpCodes.Stfld, THIS);
 654                         }
 655
 656                         //
 657                         // Copy the parameter values, if any
 658                         //
 659                         int extra = ec.IsStatic ? 0 : 1;
 660                         if (CaptureContext.Host.IsIterator)
 661                                 extra++;
 662                         if (HostsParameters){
 663                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 664
 665                                 foreach (DictionaryEntry de in captured_parameters){
 666                                         CapturedParameter cp = (CapturedParameter) de.Value;
 667
 668                                         EmitScopeInstance (ig);
 669                                         ParameterReference.EmitLdArg (ig, cp.Idx + extra);
 670                                         ig.Emit (OpCodes.Stfld, cp.FieldBuilder);
 671                                 }
 672                         }
 673
 674                         if (ParentScope != null){
 675                                 if (!ParentScope.inited)
 676                                         ParentScope.EmitInitScope (ec);
 677
 678                                 if (ParentScope.ScopeTypeBuilder != ScopeTypeBuilder) {
 679                                         //
 680                                         // Only emit initialization in our capturecontext world
 681                                         //
 682                                         if (ParentScope.CaptureContext == CaptureContext){
 683                                                 EmitScopeInstance (ig);
 684                                                 ParentScope.EmitScopeInstance (ig);
 685                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 686                                         } else {
 687                                                 EmitScopeInstance (ig);
 688                                                 ig.Emit (OpCodes.Ldarg_0);
 689                                                 ig.Emit (OpCodes.Stfld, ParentLink);
 690                                         }
 691                                 }
 692                         }
 693                         inited = true;
 694                 }
 695
 696                 public void EmitScopeInstance (ILGenerator ig)
 697                 {
 698                         if (CaptureContext.Host.IsIterator)
 699                                 ig.Emit (OpCodes.Ldarg_0);
 700                         else
 701                                 ig.Emit (OpCodes.Ldloc, scope_instance);
 702                 }
 703
 704                 static void DoPath (StringBuilder sb, ScopeInfo start)
 705                 {
 706                         if (start.ParentScope != null){
 707                                 DoPath (sb, start.ParentScope);
 708                                 sb.Append (", ");
 709                         }
 710                         sb.Append ((start.id).ToString ());
 711                 }
 712
 713                 public override string ToString ()
 714                 {
 715                         StringBuilder sb = new StringBuilder ();
 716
 717                         sb.Append ("{");
 718                         if (CaptureContext != null){
 719                                 sb.Append (CaptureContext.ToString ());
 720                                 sb.Append (":");
 721                         }
 722
 723                         DoPath (sb, this);
 724                         sb.Append ("}");
 725
 726                         return sb.ToString ();
 727                 }
 728         }
 729
 730         //
 731         // CaptureContext objects are created on demand if a method has
 732         // anonymous methods and kept on the ToplevelBlock.
 733         //
 734         // If they exist, all ToplevelBlocks in the containing block are
 735         // linked together (children pointing to their parents).
 736         //
 737         public class CaptureContext {
 738                 public static int count;
 739                 public int cc_id;
 740                 public Location loc;
 741
 742                 //
 743                 // Points to the toplevel block that owns this CaptureContext
 744                 //
 745                 ToplevelBlock toplevel_owner;
 746                 Hashtable scopes = new Hashtable ();
 747                 bool have_captured_vars = false;
 748                 bool referenced_this = false;
 749                 ScopeInfo topmost = null;
 750
 751                 //
 752                 // Captured fields
 753                 //
 754                 Hashtable captured_fields = new Hashtable ();
 755                 Hashtable captured_variables = new Hashtable ();
 756                 public Hashtable captured_parameters = new Hashtable ();
 757                 public AnonymousContainer Host;
 758
 759                 public CaptureContext (ToplevelBlock toplevel_owner, Location loc,
 760                                        AnonymousContainer host)
 761                 {
 762                         cc_id = count++;
 763                         this.toplevel_owner = toplevel_owner;
 764                         this.loc = loc;
 765
 766                         if (host != null)
 767                                 Host = host;
 768                 }
 769
 770                 void DoPath (StringBuilder sb, CaptureContext cc)
 771                 {
 772                         if (cc.ParentCaptureContext != null){
 773                                 DoPath (sb, cc.ParentCaptureContext);
 774                                 sb.Append (".");
 775                         }
 776                         sb.Append (cc.cc_id.ToString ());
 777                 }
 778
 779                 public void ReParent (ToplevelBlock new_toplevel, AnonymousContainer new_host)
 780                 {
 781                         toplevel_owner = new_toplevel;
 782                         Host = new_host;
 783
 784                         for (CaptureContext cc = ParentCaptureContext; cc != null;
 785                              cc = cc.ParentCaptureContext) {
 786                                 cc.Host = new_host;
 787                         }
 788                 }
 789
 790                 public override string ToString ()
 791                 {
 792                         StringBuilder sb = new StringBuilder ();
 793                         sb.Append ("[");
 794                         DoPath (sb, this);
 795                         sb.Append ("]");
 796                         return sb.ToString ();
 797                 }
 798
 799                 public ToplevelBlock ParentToplevel {
 800                         get {
 801                                 return toplevel_owner.Container;
 802                         }
 803                 }
 804
 805                 public CaptureContext ParentCaptureContext {
 806                         get {
 807                                 ToplevelBlock parent = ParentToplevel;
 808
 809                                 return (parent == null) ? null : parent.CaptureContext;
 810                         }
 811                 }
 812
 813                 // Returns the deepest of two scopes
 814                 public ScopeInfo Deepest (ScopeInfo a, ScopeInfo b)
 815                 {
 816                         ScopeInfo p;
 817
 818                         if (a == null)
 819                                 return b;
 820                         if (b == null)
 821                                 return a;
 822                         if (a == b)
 823                                 return a;
 824
 825                         //
 826                         // If they Scopes are on the same CaptureContext, we do the double
 827                         // checks just so if there is an invariant change in the future,
 828                         // we get the exception at the end
 829                         //
 830                         for (p = a; p != null; p = p.ParentScope)
 831                                 if (p == b)
 832                                         return a;
 833
 834                         for (p = b; p != null; p = p.ParentScope)
 835                                 if (p == a)
 836                                         return b;
 837
 838                         CaptureContext ca = a.CaptureContext;
 839                         CaptureContext cb = b.CaptureContext;
 840
 841                         for (CaptureContext c = ca; c != null; c = c.ParentCaptureContext)
 842                                 if (c == cb)
 843                                         return a;
 844
 845                         for (CaptureContext c = cb; c != null; c = c.ParentCaptureContext)
 846                                 if (c == ca)
 847                                         return b;
 848                         throw new Exception ("Should never be reached");
 849                 }
 850
 851                 void AdjustMethodScope (AnonymousContainer am, ScopeInfo scope)
 852                 {
 853                         am.Scope = Deepest (am.Scope, scope);
 854                 }
 855
 856                 void LinkScope (ScopeInfo scope, int id)
 857                 {
 858                         ScopeInfo parent = (ScopeInfo) scopes [id];
 859                         scope.ParentScope = parent;
 860                         parent.AddChild (scope);
 861
 862                         if (scope == topmost)
 863                                 topmost = parent;
 864                 }
 865
 866                 public void AddLocal (AnonymousContainer am, LocalInfo li)
 867                 {
 868                         if (li.Block.Toplevel != toplevel_owner){
 869                                 ParentCaptureContext.AddLocal (am, li);
 870                                 return;
 871                         }
 872                         int block_id = li.Block.ID;
 873                         ScopeInfo scope;
 874                         if (scopes [block_id] == null){
 875                                 scope = new ScopeInfo (this, li.Block);
 876                                 scopes [block_id] = scope;
 877                         } else
 878                                 scope = (ScopeInfo) scopes [block_id];
 879
 880                         if (topmost == null){
 881                                 topmost = scope;
 882                         } else {
 883                                 // Link to parent
 884
 885                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
 886                                         if (scopes [b.ID] != null){
 887                                                 LinkScope (scope, b.ID);
 888                                                 break;
 889                                         }
 890                                 }
 891
 892                                 if (scope.ParentScope == null && ParentCaptureContext != null){
 893                                         CaptureContext pcc = ParentCaptureContext;
 894
 895                                         for (Block b = am.ContainingBlock; b != null; b = b.Parent){
 896                                                 if (pcc.scopes [b.ID] != null){
 897                                                         pcc.LinkScope (scope, b.ID);
 898                                                         break;
 899                                                 }
 900                                         }
 901                                 }
 902                         }
 903
 904                         //
 905                         // Adjust the owner
 906                         //
 907                         if (Host != null)
 908                                 AdjustMethodScope (Host, topmost);
 909
 910                         //
 911                         // Adjust the user
 912                         //
 913                         AdjustMethodScope (am, scope);
 914
 915                         if (captured_variables [li] != null)
 916                                 return;
 917
 918                         have_captured_vars = true;
 919                         captured_variables [li] = li;
 920                         scope.AddLocal (li);
 921                 }
 922
 923                 //
 924                 // Retursn the CaptureContext for the block that defines the parameter `name'
 925                 //
 926                 static CaptureContext _ContextForParameter (ToplevelBlock current, string name)
 927                 {
 928                         ToplevelBlock container = current.Container;
 929                         if (container != null){
 930                                 CaptureContext cc = _ContextForParameter (container, name);
 931                                 if (cc != null)
 932                                         return cc;
 933                         }
 934                         if (current.IsParameterReference (name))
 935                                 return current.ToplevelBlockCaptureContext;
 936                         return null;
 937                 }
 938
 939                 static CaptureContext ContextForParameter (ToplevelBlock current, string name)
 940                 {
 941                         CaptureContext cc = _ContextForParameter (current, name);
 942                         if (cc == null)
 943                                 throw new Exception (String.Format ("request for parameteter {0} failed: not found", name));
 944                         return cc;
 945                 }
 946
 947                 //
 948                 // Records the captured parameter at the appropriate CaptureContext
 949                 //
 950                 public void AddParameter (EmitContext ec, AnonymousContainer am,
 951                                           string name, Type t, int idx)
 952                 {
 953                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
 954
 955                         cc.AddParameterToContext (am, name, t, idx);
 956                 }
 957
 958                 //
 959                 // Records the parameters in the context
 960                 //
 961                 public void AddParameterToContext (AnonymousContainer am, string name, Type t, int idx)
 962                 {
 963                         if (captured_parameters == null)
 964                                 captured_parameters = new Hashtable ();
 965                         if (captured_parameters [name] != null)
 966                                 return;
 967                         captured_parameters [name] = new CapturedParameter (t, idx);
 968
 969                         if (topmost == null){
 970                                 //
 971                                 // Create one ScopeInfo, if there are none.
 972                                 //
 973                                 topmost = new ScopeInfo (this, toplevel_owner);
 974                                 scopes [toplevel_owner.ID] = topmost;
 975                         } else {
 976                                 //
 977                                 // If the topmost ScopeInfo is not at the topblock level, insert
 978                                 // a new ScopeInfo there.
 979                                 //
 980                                 // FIXME: This code probably should be evolved to be like the code
 981                                 // in AddLocal
 982                                 //
 983                                 if (topmost.ScopeBlock != toplevel_owner){
 984                                         ScopeInfo par_si = new ScopeInfo (this, toplevel_owner);
 985                                         ScopeInfo old_top = topmost;
 986                                         scopes [toplevel_owner.ID] = topmost;
 987                                         topmost.ParentScope = par_si;
 988                                         topmost = par_si;
 989                                         topmost.AddChild (old_top);
 990                                 }
 991                         }
 992
 993                         topmost.HostsParameters = true;
 994                         AdjustMethodScope (am, topmost);
 995                 }
 996
 997                 //
 998                 // Captured fields are only recorded on the topmost CaptureContext, because that
 999                 // one is the one linked to the owner of instance fields
1000                 //
1001                 public void AddField (FieldExpr fe)
1002                 {
1003                         if (fe.FieldInfo.IsStatic)
1004                                 throw new Exception ("Attempt to register a static field as a captured field");
1005
1006                         CaptureContext parent = ParentCaptureContext;
1007                         if (parent != null)
1008                                 parent.AddField (fe);
1009                         else
1010                                 captured_fields [fe] = fe;
1011                 }
1012
1013                 public void CaptureThis ()
1014                 {
1015                         CaptureContext parent = ParentCaptureContext;
1016                         if (parent != null)
1017                                 parent.CaptureThis ();
1018                         referenced_this = true;
1019                 }
1020
1021                 public bool HaveCapturedVariables {
1022                         get {
1023                                 return have_captured_vars;
1024                         }
1025                 }
1026
1027                 public bool HaveCapturedFields {
1028                         get {
1029                                 CaptureContext parent = ParentCaptureContext;
1030                                 if (parent != null)
1031                                         return parent.HaveCapturedFields;
1032                                 return captured_fields.Count > 0;
1033                         }
1034                 }
1035
1036                 public bool IsCaptured (LocalInfo local)
1037                 {
1038                         foreach (ScopeInfo si in scopes.Values){
1039                                 if (si.IsCaptured (local))
1040                                         return true;
1041                         }
1042                         return false;
1043                 }
1044
1045                 //
1046                 // Returns whether the parameter is captured
1047                 //
1048                 public bool IsParameterCaptured (string name)
1049                 {
1050                         if (ParentCaptureContext != null && ParentCaptureContext.IsParameterCaptured (name))
1051                                 return true;
1052
1053                         if (captured_parameters != null)
1054                                 return captured_parameters [name] != null;
1055                         return false;
1056                 }
1057
1058                 public void EmitAnonymousHelperClasses (EmitContext ec)
1059                 {
1060                         if (topmost != null){
1061                                 topmost.NeedThis = HaveCapturedFields || referenced_this;
1062                                 topmost.EmitScopeType (ec);
1063                         }
1064                 }
1065
1066                 public void CloseAnonymousHelperClasses ()
1067                 {
1068                         if (topmost != null)
1069                                 topmost.CloseTypes ();
1070                 }
1071
1072                 public void EmitInitScope (EmitContext ec)
1073                 {
1074                         EmitAnonymousHelperClasses (ec);
1075                         if (topmost != null)
1076                                 topmost.EmitInitScope (ec);
1077                 }
1078
1079                 ScopeInfo GetScopeFromBlock (EmitContext ec, Block b)
1080                 {
1081                         ScopeInfo si;
1082
1083                         si = (ScopeInfo) scopes [b.ID];
1084                         if (si == null)
1085                                 throw new Exception ("Si is null for block " + b.ID);
1086                         si.EmitInitScope (ec);
1087
1088                         return si;
1089                 }
1090
1091                 //
1092                 // Emits the opcodes necessary to load the instance of the captured
1093                 // variable in `li'
1094                 //
1095                 public void EmitCapturedVariableInstance (EmitContext ec, LocalInfo li,
1096                                                           AnonymousContainer am)
1097                 {
1098                         ILGenerator ig = ec.ig;
1099                         ScopeInfo si;
1100
1101                         if (li.Block.Toplevel == toplevel_owner){
1102                                 si = GetScopeFromBlock (ec, li.Block);
1103                                 si.EmitScopeInstance (ig);
1104                                 return;
1105                         }
1106
1107                         si = am.Scope;
1108                         ig.Emit (OpCodes.Ldarg_0);
1109                         if (si != null){
1110                                 if (am.IsIterator && (si.ScopeBlock.Toplevel == li.Block.Toplevel)) {
1111                                         return;
1112                                 }
1113
1114                                 while (si.ScopeBlock.ID != li.Block.ID){
1115                                         if (si.ParentLink != null)
1116                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
1117                                         si = si.ParentScope;
1118                                         if (si == null) {
1119                                                 si = am.Scope;
1120                                                 Console.WriteLine ("Target: {0} {1}", li.Block.ID, li.Name);
1121                                                 while (si.ScopeBlock.ID != li.Block.ID){
1122                                                         Console.WriteLine ("Trying: {0}", si.ScopeBlock.ID);
1123                                                         si = si.ParentScope;
1124                                                 }
1125
1126                                                 throw new Exception (
1127                                                              String.Format ("Never found block {0} starting at {1} while looking up {2}",
1128                                                                             li.Block.ID, am.Scope.ScopeBlock.ID, li.Name));
1129                                         }
1130                                 }
1131                         }
1132                 }
1133
1134                 //
1135                 // Internal routine that loads the instance to reach parameter `name'
1136                 //
1137                 void EmitParameterInstance (EmitContext ec, string name)
1138                 {
1139                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1140                         if (cc != this){
1141                                 cc.EmitParameterInstance (ec, name);
1142                                 return;
1143                         }
1144
1145                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1146                         if (par_info != null){
1147                                 //
1148                                 // FIXME: implementing this.
1149                                 //
1150                         }
1151                         ILGenerator ig = ec.ig;
1152
1153                         ScopeInfo si;
1154
1155                         if (ec.CurrentBlock.Toplevel == toplevel_owner){
1156                                 si = GetScopeFromBlock (ec, toplevel_owner);
1157                                 si.EmitScopeInstance (ig);
1158                                 return;
1159                         }
1160
1161                         si = ec.CurrentAnonymousMethod.Scope;
1162                         ig.Emit (OpCodes.Ldarg_0);
1163                         if (si != null){
1164                                 while (si.ParentLink != null) {
1165                                         ig.Emit (OpCodes.Ldfld, si.ParentLink);
1166                                         si = si.ParentScope;
1167                                 }
1168                         }
1169                 }
1170
1171                 //
1172                 // Emits the code necessary to load the parameter named `name' within
1173                 // an anonymous method.
1174                 //
1175                 public void EmitParameter (EmitContext ec, string name)
1176                 {
1177                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1178                         if (cc != this){
1179                                 cc.EmitParameter (ec, name);
1180                                 return;
1181                         }
1182                         EmitParameterInstance (ec, name);
1183                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1184                         if (par_info != null){
1185                                 //
1186                                 // FIXME: implementing this.
1187                                 //
1188                         }
1189                         ec.ig.Emit (OpCodes.Ldfld, par_info.FieldBuilder);
1190                 }
1191
1192                 //
1193                 // Implements the assignment of `source' to the paramenter named `name' within
1194                 // an anonymous method.
1195                 //
1196                 public void EmitAssignParameter (EmitContext ec, string name, Expression source, bool leave_copy, bool prepare_for_load)
1197                 {
1198                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1199                         if (cc != this){
1200                                 cc.EmitAssignParameter (ec, name, source, leave_copy, prepare_for_load);
1201                                 return;
1202                         }
1203                         ILGenerator ig = ec.ig;
1204                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1205
1206                         EmitParameterInstance (ec, name);
1207                         source.Emit (ec);
1208                         if (leave_copy)
1209                                 ig.Emit (OpCodes.Dup);
1210                         ig.Emit (OpCodes.Stfld, par_info.FieldBuilder);
1211                 }
1212
1213                 //
1214                 // Emits the address for the parameter named `name' within
1215                 // an anonymous method.
1216                 //
1217                 public void EmitAddressOfParameter (EmitContext ec, string name)
1218                 {
1219                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1220                         if (cc != this){
1221                                 cc.EmitAddressOfParameter (ec, name);
1222                                 return;
1223                         }
1224                         EmitParameterInstance (ec, name);
1225                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1226                         ec.ig.Emit (OpCodes.Ldflda, par_info.FieldBuilder);
1227                 }
1228
1229                 //
1230                 // The following methods are only invoked on the host for the
1231                 // anonymous method.
1232                 //
1233                 public void EmitMethodHostInstance (EmitContext target, AnonymousContainer am)
1234                 {
1235                         ILGenerator ig = target.ig;
1236                         ScopeInfo si = am.Scope;
1237
1238                         if (si == null){
1239                                 ig.Emit (OpCodes.Ldarg_0);
1240                                 return;
1241                         }
1242
1243                         si.EmitInitScope (target);
1244                         si.EmitScopeInstance (ig);
1245                 }
1246
1247                 ArrayList all_scopes = new ArrayList ();
1248
1249                 public void AddScope (ScopeInfo si)
1250                 {
1251                         all_scopes.Add (si);
1252                         toplevel_owner.RegisterCaptureContext (this);
1253                 }
1254
1255                 //
1256                 // Links any scopes that were not linked previously
1257                 //
1258                 public void AdjustScopes ()
1259                 {
1260                         foreach (ScopeInfo scope in all_scopes){
1261                                 if (scope.ParentScope != null)
1262                                         continue;
1263
1264                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
1265                                         if (scopes [b.ID] != null){
1266                                                 LinkScope (scope, b.ID);
1267                                                 break;
1268                                         }
1269                                 }
1270
1271                                 if (scope.ParentScope == null && ParentCaptureContext != null){
1272                                         CaptureContext pcc = ParentCaptureContext;
1273
1274                                         for (Block b = Host.ContainingBlock; b != null; b = b.Parent){
1275                                                 if (pcc.scopes [b.ID] != null){
1276                                                         pcc.LinkScope (scope, b.ID);
1277                                                         break;
1278                                                 }
1279                                         }
1280                                 }
1281                         }
1282                 }
1283         }
1284 }