mcs/gmcs/anonymous.cs

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