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