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