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