mcs/gmcs/anonymous.cs

   1 //
   2 // anonymous.cs: Support for anonymous methods
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximain.com)
   6 //
   7 // (C) 2003, 2004 Novell, Inc.
   8 //
   9 // TODO: Ideally, we should have the helper classes emited as a hierarchy to map
  10 // their nesting, and have the visibility set to private, instead of NestedAssembly
  11 //
  12 //
  13 //
  14
  15 using System;
  16 using System.Text;
  17 using System.Collections;
  18 using System.Reflection;
  19 using System.Reflection.Emit;
  20
  21 namespace Mono.CSharp {
  22
  23         public class AnonymousMethod : Expression {
  24                 // Used to generate unique method names.
  25                 static int anonymous_method_count;
  26
  27                 // An array list of AnonymousMethodParameter or null
  28                 public Parameters Parameters;
  29
  30                 //
  31                 // The block that makes up the body for the anonymous mehtod
  32                 //
  33                 public ToplevelBlock Block;
  34
  35                 //
  36                 // The container block for this anonymous method.
  37                 //
  38                 public Block ContainingBlock;
  39
  40                 //
  41                 // The implicit method we create
  42                 //
  43                 public Method method;
  44
  45                 MethodInfo invoke_mb;
  46
  47                 // The emit context for the anonymous method
  48                 public EmitContext aec;
  49                 public InternalParameters amp;
  50                 bool unreachable;
  51
  52                 //
  53                 // The modifiers applied to the method, we aggregate them
  54                 //
  55                 int method_modifiers = Modifiers.PRIVATE;
  56
  57                 //
  58                 // During the resolve stage of the anonymous method body,
  59                 // we discover the actual scope where we are hosted, or
  60                 // null to host the method in the same class
  61                 //
  62                 public ScopeInfo Scope;
  63
  64                 //
  65                 // Points to our container anonymous method if its present
  66                 //
  67                 public AnonymousMethod ContainerAnonymousMethod;
  68
  69                 public AnonymousMethod (Parameters parameters, ToplevelBlock container, ToplevelBlock block, Location l)
  70                 {
  71                         Parameters = parameters;
  72                         Block = block;
  73                         loc = l;
  74
  75                         //
  76                         // The order is important: this setups the CaptureContext tree hierarchy.
  77                         //
  78                         container.SetHaveAnonymousMethods (l, this);
  79                         block.SetHaveAnonymousMethods (l, this);
  80                 }
  81
  82                 public override Expression DoResolve (EmitContext ec)
  83                 {
  84                         //
  85                         // Set class type, set type
  86                         //
  87
  88                         eclass = ExprClass.Value;
  89
  90                         //
  91                         // This hack means `The type is not accessible
  92                         // anywhere', we depend on special conversion
  93                         // rules.
  94                         //
  95                         type = TypeManager.anonymous_method_type;
  96
  97                         return this;
  98                 }
  99
 100                 public override void Emit (EmitContext ec)
 101                 {
 102                         // nothing, as we only exist to not do anything.
 103                 }
 104
 105                 //
 106                 // Creates the host for the anonymous method
 107                 //
 108                 bool CreateMethodHost (EmitContext ec, Type return_type)
 109                 {
 110                         //
 111                         // Crude hack follows: we replace the TypeBuilder during the
 112                         // definition to get the method hosted in the right class
 113                         //
 114
 115                         TypeBuilder current_type = ec.TypeContainer.TypeBuilder;
 116                         TypeBuilder type_host = (Scope == null ) // || Scope.ScopeTypeBuilder == null)
 117                                 ? current_type : Scope.ScopeTypeBuilder;
 118
 119                         if (current_type == null)
 120                                 throw new Exception ("The current_type is null");
 121
 122                         if (type_host == null)
 123                                 throw new Exception ("Type host is null");
 124
 125                         if (current_type == type_host && ec.IsStatic){
 126                                 if (ec.IsStatic){
 127                                         method_modifiers |= Modifiers.STATIC;
 128                                 }
 129                                 current_type = null;
 130                         }
 131
 132                         method = new Method (
 133                                 (TypeContainer) ec.TypeContainer, null,
 134                                 new TypeExpression (return_type, loc),
 135                                 method_modifiers, false, new MemberName ("<#AnonymousMethod>" + anonymous_method_count++),
 136                                 Parameters, null, loc);
 137                         method.Block = Block;
 138
 139                         //
 140                         // Swap the TypeBuilder while we define the method, then restore
 141                         //
 142                         if (current_type != null)
 143                                 ec.TypeContainer.TypeBuilder = type_host;
 144                         bool res = method.Define ();
 145                         if (current_type != null)
 146                                 ec.TypeContainer.TypeBuilder = current_type;
 147                         return res;
 148                 }
 149
 150                 void Error_ParameterMismatch (Type t)
 151                 {
 152                         Report.Error (1661, loc, "Anonymous method could not be converted to delegate `" +
 153                                       "{0}' since there is a parameter mismatch", t);
 154         }
 155
 156                 //
 157                 // Returns true if this anonymous method can be implicitly
 158                 // converted to the delegate type `delegate_type'
 159                 //
 160                 public Expression Compatible (EmitContext ec, Type delegate_type, bool probe)
 161                 {
 162                         //
 163                         // At this point its the first time we know the return type that is
 164                         // needed for the anonymous method.  We create the method here.
 165                         //
 166
 167                         MethodGroupExpr invoke_mg = Delegate.GetInvokeMethod (ec, delegate_type, loc);
 168                         invoke_mb = (MethodInfo) invoke_mg.Methods [0];
 169                         ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
 170
 171                         if (Parameters == null){
 172                                 int i, j;
 173
 174                                 //
 175                                 // We provide a set of inaccessible parameters
 176                                 //
 177                                 int params_idx = -1;
 178                                 for (i = 0; i < invoke_pd.Count; i++){
 179                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 180                                                 params_idx = i;
 181                                 }
 182                                 int n = invoke_pd.Count - (params_idx != -1 ? 1 : 0);
 183                                 Parameter [] fixedpars = new Parameter [n];
 184
 185                                 for (i =  j = 0; i < invoke_pd.Count; i++){
 186                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 187                                                 continue;
 188                                         fixedpars [j] = new Parameter (
 189                                                 new TypeExpression (invoke_pd.ParameterType (i), loc),
 190                                                 "+" + j, invoke_pd.ParameterModifier (i), null);
 191                                         j++;
 192                                 }
 193
 194                                 Parameter variable = null;
 195                                 if (params_idx != -1){
 196                                         variable = new Parameter (
 197                                                 new TypeExpression (invoke_pd.ParameterType (params_idx), loc),
 198                                                 "+" + params_idx, invoke_pd.ParameterModifier (params_idx), null);
 199                                 }
 200
 201                                 Parameters = new Parameters (fixedpars, variable, loc);
 202                         }
 203
 204                         //
 205                         // First, parameter types of `delegate_type' must be compatible
 206                         // with the anonymous method.
 207                         //
 208                         amp = new InternalParameters (Parameters.GetParameterInfo (ec), Parameters);
 209
 210                         if (amp.Count != invoke_pd.Count){
 211                                 if (!probe){
 212                                         Report.Error (1593, loc,
 213                                               "Anonymous method has {0} parameters, while delegate requires {1}",
 214                                               amp.Count, invoke_pd.Count);
 215                                         Error_ParameterMismatch (delegate_type);
 216                                 }
 217                                 return null;
 218                         }
 219
 220                         for (int i = 0; i < amp.Count; i++){
 221                                 Parameter.Modifier amp_mod = amp.ParameterModifier (i);
 222
 223                                 if ((amp_mod & (Parameter.Modifier.OUT | Parameter.Modifier.REF)) != 0){
 224                                         if (!probe){
 225                                                 Error_ParameterMismatch (delegate_type);
 226                                                 Report.Error (1677, loc, "Parameter '{0}' should not be declared with the '{1}' keyword",
 227                                                         i+1, amp.ModifierDesc (i));
 228                                         }
 229                                         return null;
 230                                 }
 231
 232                                 if (amp_mod != invoke_pd.ParameterModifier (i)){
 233                                         if (!probe){
 234                                                 Report.Error (1676, loc,
 235                                                       "Signature mismatch in parameter modifier for parameter #0", i + 1);
 236                                                 Error_ParameterMismatch (delegate_type);
 237                                         }
 238                                         return null;
 239                                 }
 240
 241                                 if (amp.ParameterType (i) != invoke_pd.ParameterType (i)){
 242                                         if (!probe){
 243                                                 Report.Error (1678, loc,
 244                                                                       "Signature mismatch in parameter {0}: need `{1}' got `{2}'", i + 1,
 245                                                                       TypeManager.CSharpName (invoke_pd.ParameterType (i)),
 246                                                                       TypeManager.CSharpName (amp.ParameterType (i)));
 247                                                 Error_ParameterMismatch (delegate_type);
 248                                         }
 249                                         return null;
 250                                 }
 251                         }
 252
 253                         //
 254                         // If we are only probing, return ourselves
 255                         //
 256                         if (probe)
 257                                 return this;
 258
 259                         //
 260                         // Second: the return type of the delegate must be compatible with
 261                         // the anonymous type.   Instead of doing a pass to examine the block
 262                         // we satisfy the rule by setting the return type on the EmitContext
 263                         // to be the delegate type return type.
 264                         //
 265
 266                         //MethodBuilder builder = method_data.MethodBuilder;
 267                         //ILGenerator ig = builder.GetILGenerator ();
 268
 269
 270                         aec = new EmitContext (
 271                                 ec.TypeContainer, ec.DeclSpace, loc, null,
 272                                 invoke_mb.ReturnType,
 273                                 /* REVIEW */ (ec.InIterator ? Modifiers.METHOD_YIELDS : 0) |
 274                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0) |
 275                                 (ec.IsStatic ? Modifiers.STATIC : 0),
 276                                 /* No constructor */ false);
 277
 278                         aec.CurrentAnonymousMethod = this;
 279                         ContainerAnonymousMethod = ec.CurrentAnonymousMethod;
 280                         ContainingBlock = ec.CurrentBlock;
 281
 282                         if (aec.ResolveTopBlock (ec, Block, amp, loc, out unreachable))
 283                                 return new AnonymousDelegate (this, delegate_type, loc).Resolve (ec);
 284
 285                         return null;
 286                 }
 287
 288                 public MethodBuilder GetMethodBuilder ()
 289                 {
 290                         return method.MethodData.MethodBuilder;
 291                 }
 292
 293                 public bool EmitMethod (EmitContext ec)
 294                 {
 295                         if (!CreateMethodHost (ec, invoke_mb.ReturnType))
 296                                 return false;
 297
 298                         MethodBuilder builder = GetMethodBuilder ();
 299                         ILGenerator ig = builder.GetILGenerator ();
 300                         aec.ig = ig;
 301
 302                         Parameters.LabelParameters (aec, builder, loc);
 303
 304                         //
 305                         // Adjust based on the computed state of the
 306                         // method from CreateMethodHost
 307
 308                         aec.MethodIsStatic = (method_modifiers & Modifiers.STATIC) != 0;
 309
 310                         aec.EmitMeta (Block, amp);
 311                         aec.EmitResolvedTopBlock (Block, unreachable);
 312                         return true;
 313                 }
 314
 315                 public static void Error_AddressOfCapturedVar (string name, Location loc)
 316                 {
 317                         Report.Error (1686, loc,
 318                                       "Variable {0} is captured in an anonymous method and its address is also being taken: they are exclusive", name);
 319                 }
 320         }
 321
 322         //
 323         // This will emit the code for the delegate, as well delegate creation on the host
 324         //
 325         public class AnonymousDelegate : DelegateCreation {
 326                 AnonymousMethod am;
 327
 328                 public AnonymousDelegate (AnonymousMethod am, Type target_type, Location l)
 329                 {
 330                         type = target_type;
 331                         loc = l;
 332                         this.am = am;
 333                 }
 334
 335                 public override Expression DoResolve (EmitContext ec)
 336                 {
 337                         eclass = ExprClass.Value;
 338
 339                         return this;
 340                 }
 341
 342                 public override void Emit (EmitContext ec)
 343                 {
 344                         if (!am.EmitMethod (ec))
 345                                 return;
 346
 347                         //
 348                         // Now emit the delegate creation.
 349                         //
 350                         if ((am.method.ModFlags & Modifiers.STATIC) == 0)
 351                                 delegate_instance_expression = new AnonymousInstance (am);
 352
 353                         Expression ml = Expression.MemberLookup (ec, type, ".ctor", loc);
 354                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 355                         delegate_method = am.GetMethodBuilder ();
 356                         base.Emit (ec);
 357                 }
 358
 359                 class AnonymousInstance : Expression {
 360                         AnonymousMethod am;
 361
 362                         public AnonymousInstance (AnonymousMethod am)
 363                         {
 364                                 this.am = am;
 365                                 eclass = ExprClass.Value;
 366                         }
 367
 368                         public override Expression DoResolve (EmitContext ec)
 369                         {
 370                                 return this;
 371                         }
 372
 373                         public override void Emit (EmitContext ec)
 374                         {
 375                                 am.aec.EmitMethodHostInstance (ec, am);
 376                         }
 377                 }
 378         }
 379
 380         class CapturedParameter {
 381                 public Type Type;
 382                 public FieldBuilder FieldBuilder;
 383                 public int Idx;
 384
 385                 public CapturedParameter (Type type, int idx)
 386                 {
 387                         Type = type;
 388                         Idx = idx;
 389                 }
 390         }
 391
 392         //
 393         // Here we cluster all the variables captured on a given scope, we also
 394         // keep some extra information that might be required on each scope.
 395         //
 396         public class ScopeInfo {
 397                 public CaptureContext CaptureContext;
 398                 public ScopeInfo ParentScope;
 399                 public Block ScopeBlock;
 400                 public bool NeedThis = false;
 401                 public bool HostsParameters = false;
 402
 403                 // For tracking the number of scopes created.
 404                 public int id;
 405                 static int count;
 406                 bool inited = false;
 407
 408                 ArrayList locals = new ArrayList ();
 409                 ArrayList children = new ArrayList ();
 410
 411                 //
 412                 // The types and fields generated
 413                 //
 414                 public TypeBuilder ScopeTypeBuilder;
 415                 public ConstructorBuilder ScopeConstructor;
 416                 public FieldBuilder THIS;
 417                 public FieldBuilder ParentLink;
 418
 419                 //
 420                 // Points to the object of type `ScopeTypeBuilder' that
 421                 // holds the data for the scope
 422                 //
 423                 public LocalBuilder ScopeInstance;
 424
 425
 426                 public ScopeInfo (CaptureContext cc, Block b)
 427                 {
 428                         CaptureContext = cc;
 429                         ScopeBlock = b;
 430                         id = count++;
 431
 432                         cc.AddScope (this);
 433                 }
 434
 435                 public void AddLocal (LocalInfo li)
 436                 {
 437                         if (locals.Contains (li))
 438                                 return;
 439
 440                         locals.Add (li);
 441 }
 442
 443                 public bool IsCaptured (LocalInfo li)
 444                 {
 445                         return locals.Contains (li);
 446                 }
 447
 448                 public void AddChild (ScopeInfo si)
 449                 {
 450                         if (children.Contains (si))
 451                                 return;
 452                         children.Add (si);
 453                 }
 454
 455                 static int indent = 0;
 456
 457                 void Pad ()
 458                 {
 459                         for (int i = 0; i < indent; i++)
 460                                 Console.Write ("    ");
 461                 }
 462
 463                 void EmitDebug ()
 464                 {
 465                         //Console.WriteLine (Environment.StackTrace);
 466                         Pad ();
 467                         Console.WriteLine ("START");
 468                         indent++;
 469                         Pad ();
 470                         Console.WriteLine ("NeedThis=" + NeedThis);
 471                         foreach (LocalInfo li in locals){
 472                                 Pad ();
 473                                 Console.WriteLine ("var {0}", li.Name);
 474                         }
 475
 476                         foreach (ScopeInfo si in children)
 477                                 si.EmitDebug ();
 478                         indent--;
 479                         Pad ();
 480                         Console.WriteLine ("END");
 481                 }
 482
 483                 public string MakeHelperName ()
 484                 {
 485                         return String.Format ("<>AnonHelp<{0}>", id);
 486                 }
 487
 488                 public void EmitScopeConstructor ()
 489                 {
 490                         Type [] constructor_types = TypeManager.NoTypes;
 491                         Parameters constructor_parameters = Parameters.EmptyReadOnlyParameters;
 492                         ScopeConstructor = ScopeTypeBuilder.DefineConstructor (
 493                                 MethodAttributes.Public | MethodAttributes.HideBySig |
 494                                 MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
 495                                 CallingConventions.HasThis, constructor_types);
 496                         InternalParameters parameter_info = new InternalParameters (constructor_types, constructor_parameters);
 497                         TypeManager.RegisterMethod (ScopeConstructor, parameter_info, constructor_types);
 498
 499                         ILGenerator cig = ScopeConstructor.GetILGenerator ();
 500                         cig.Emit (OpCodes.Ldarg_0);
 501                         cig.Emit (OpCodes.Call, TypeManager.object_ctor);
 502                         cig.Emit (OpCodes.Ret);
 503                 }
 504
 505                 public void EmitScopeType (EmitContext ec)
 506                 {
 507                         //EmitDebug ();
 508
 509                         if (ScopeTypeBuilder != null)
 510                                 return;
 511
 512                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 513
 514                         ScopeTypeBuilder = container.DefineNestedType (
 515                                 MakeHelperName (), TypeAttributes.AutoLayout | TypeAttributes.Class | TypeAttributes.NestedAssembly,
 516                                 TypeManager.object_type, null);
 517
 518                         if (NeedThis)
 519                                 THIS = ScopeTypeBuilder.DefineField ("<>THIS", container, FieldAttributes.Assembly);
 520
 521                         if (ParentScope != null){
 522                                 if (ParentScope.ScopeTypeBuilder == null){
 523                                         throw new Exception (String.Format ("My parent has not been initialized {0} and {1}", ParentScope, this));
 524                                 }
 525
 526                                 ParentLink = ScopeTypeBuilder.DefineField ("<>parent", ParentScope.ScopeTypeBuilder,
 527                                                                            FieldAttributes.Assembly);
 528                         }
 529
 530                         if (NeedThis && ParentScope != null)
 531                                 throw new Exception ("I was not expecting THIS && having a parent");
 532
 533                         foreach (LocalInfo info in locals){
 534                                 info.FieldBuilder = ScopeTypeBuilder.DefineField (
 535                                         info.Name, info.VariableType, FieldAttributes.Assembly);
 536                         }
 537
 538                         if (HostsParameters){
 539                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 540
 541                                 foreach (DictionaryEntry de in captured_parameters){
 542                                         string name = (string) de.Key;
 543                                         CapturedParameter cp = (CapturedParameter) de.Value;
 544                                         FieldBuilder fb;
 545
 546                                         fb = ScopeTypeBuilder.DefineField ("<p:" + name + ">", cp.Type, FieldAttributes.Assembly);
 547                                         cp.FieldBuilder = fb;
 548                                 }
 549                         }
 550
 551                         EmitScopeConstructor ();
 552                         foreach (ScopeInfo si in children){
 553                                 si.EmitScopeType (ec);
 554                         }
 555                 }
 556
 557                 public void CloseTypes ()
 558                 {
 559                         RootContext.RegisterCompilerGeneratedType (ScopeTypeBuilder);
 560                         foreach (ScopeInfo si in children)
 561                                 si.CloseTypes ();
 562                 }
 563
 564                 //
 565                 // Emits the initialization code for the scope
 566                 //
 567                 public void EmitInitScope (EmitContext ec)
 568                 {
 569                         ILGenerator ig = ec.ig;
 570
 571                         if (inited)
 572                                 return;
 573
 574                         ig.Emit (OpCodes.Newobj, (ConstructorInfo) ScopeConstructor);
 575                         ScopeInstance = ig.DeclareLocal (ScopeTypeBuilder);
 576                         ig.Emit (OpCodes.Stloc, ScopeInstance);
 577
 578                         if (THIS != null){
 579                                 ig.Emit (OpCodes.Ldloc, ScopeInstance);
 580                                 ig.Emit (OpCodes.Ldarg_0);
 581                                 ig.Emit (OpCodes.Stfld, THIS);
 582                         }
 583
 584                         //
 585                         // Copy the parameter values, if any
 586                         //
 587                         int extra = ec.IsStatic ? 0 : 1;
 588                         if (HostsParameters){
 589                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 590
 591                                 foreach (DictionaryEntry de in captured_parameters){
 592                                         CapturedParameter cp = (CapturedParameter) de.Value;
 593
 594                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 595                                         ParameterReference.EmitLdArg (ig, cp.Idx + extra);
 596                                         ig.Emit (OpCodes.Stfld, cp.FieldBuilder);
 597                                 }
 598                         }
 599
 600                         if (ParentScope != null){
 601                                 if (!ParentScope.inited)
 602                                         ParentScope.EmitInitScope (ec);
 603
 604                                 //
 605                                 // Only emit initialization in our capturecontext world
 606                                 //
 607                                 if (ParentScope.CaptureContext == CaptureContext){
 608                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 609                                         ig.Emit (OpCodes.Ldloc, ParentScope.ScopeInstance);
 610                                         ig.Emit (OpCodes.Stfld, ParentLink);
 611                                 } else {
 612                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 613                                         ig.Emit (OpCodes.Ldarg_0);
 614                                         ig.Emit (OpCodes.Stfld, ParentLink);
 615                                 }
 616                         }
 617                         inited = true;
 618                 }
 619
 620                 static void DoPath (StringBuilder sb, ScopeInfo start)
 621                 {
 622                         if (start.ParentScope != null){
 623                                 DoPath (sb, start.ParentScope);
 624                                 sb.Append (", ");
 625                         }
 626                         sb.Append ((start.id).ToString ());
 627                 }
 628
 629                 public override string ToString ()
 630                 {
 631                         StringBuilder sb = new StringBuilder ();
 632
 633                         sb.Append ("{");
 634                         if (CaptureContext != null){
 635                                 sb.Append (CaptureContext.ToString ());
 636                                 sb.Append (":");
 637                         }
 638
 639                         DoPath (sb, this);
 640                         sb.Append ("}");
 641
 642                         return sb.ToString ();
 643                 }
 644         }
 645
 646         //
 647         // CaptureContext objects are created on demand if a method has
 648         // anonymous methods and kept on the ToplevelBlock.
 649         //
 650         // If they exist, all ToplevelBlocks in the containing block are
 651         // linked together (children pointing to their parents).
 652         //
 653         public class CaptureContext {
 654                 public static int count;
 655                 public int cc_id;
 656                 public Location loc;
 657
 658                 //
 659                 // Points to the toplevel block that owns this CaptureContext
 660                 //
 661                 ToplevelBlock toplevel_owner;
 662                 Hashtable scopes = new Hashtable ();
 663                 bool have_captured_vars = false;
 664                 bool referenced_this = 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                 public void CaptureThis ()
 911                 {
 912                         CaptureContext parent = ParentCaptureContext;
 913                         if (parent != null)
 914                                 parent.CaptureThis ();
 915                         referenced_this = true;
 916                 }
 917
 918                 public bool HaveCapturedVariables {
 919                         get {
 920                                 return have_captured_vars;
 921                         }
 922                 }
 923
 924                 public bool HaveCapturedFields {
 925                         get {
 926                                 CaptureContext parent = ParentCaptureContext;
 927                                 if (parent != null)
 928                                         return parent.HaveCapturedFields;
 929                                 return captured_fields.Count > 0;
 930                         }
 931                 }
 932
 933                 public bool IsCaptured (LocalInfo local)
 934                 {
 935                         foreach (ScopeInfo si in scopes.Values){
 936                                 if (si.IsCaptured (local))
 937                                         return true;
 938                         }
 939                         return false;
 940                 }
 941
 942                 //
 943                 // Returns whether the parameter is captured
 944                 //
 945                 public bool IsParameterCaptured (string name)
 946                 {
 947                         if (ParentCaptureContext != null && ParentCaptureContext.IsParameterCaptured (name))
 948                                 return true;
 949
 950                         if (captured_parameters != null)
 951                                 return captured_parameters [name] != null;
 952                         return false;
 953                 }
 954
 955                 public void EmitAnonymousHelperClasses (EmitContext ec)
 956                 {
 957                         if (topmost != null){
 958                                 topmost.NeedThis = HaveCapturedFields || referenced_this;
 959                                 topmost.EmitScopeType (ec);
 960                         }
 961                 }
 962
 963                 public void CloseAnonymousHelperClasses ()
 964                 {
 965                         if (topmost != null)
 966                                 topmost.CloseTypes ();
 967                 }
 968
 969                 ScopeInfo GetScopeFromBlock (EmitContext ec, Block b)
 970                 {
 971                         ScopeInfo si;
 972
 973                         si = (ScopeInfo) scopes [b.ID];
 974                         if (si == null)
 975                                 throw new Exception ("Si is null for block " + b.ID);
 976                         si.EmitInitScope (ec);
 977
 978                         return si;
 979                 }
 980
 981                 //
 982                 // Emits the opcodes necessary to load the instance of the captured
 983                 // variable in `li'
 984                 //
 985                 public void EmitCapturedVariableInstance (EmitContext ec, LocalInfo li, AnonymousMethod am)
 986                 {
 987                         ILGenerator ig = ec.ig;
 988                         ScopeInfo si;
 989
 990                         if (li.Block.Toplevel == toplevel_owner){
 991                                 si = GetScopeFromBlock (ec, li.Block);
 992                                 ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
 993                                 return;
 994                         }
 995
 996                         si = am.Scope;
 997                         ig.Emit (OpCodes.Ldarg_0);
 998                         if (si != null){
 999                                 while (si.ScopeBlock.ID != li.Block.ID){
1000                                         if (si.ParentLink != null)
1001                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
1002                                         si = si.ParentScope;
1003                                         if (si == null)
1004                                                 throw new Exception (
1005                                                              String.Format ("Never found block {0} starting at {1} while looking up {2}",
1006                                                                             li.Block.ID, am.Scope.ScopeBlock.ID, li.Name));
1007                                 }
1008                         }
1009                 }
1010
1011                 //
1012                 // Internal routine that loads the instance to reach parameter `name'
1013                 //
1014                 void EmitParameterInstance (EmitContext ec, string name)
1015                 {
1016                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1017                         if (cc != this){
1018                                 cc.EmitParameterInstance (ec, name);
1019                                 return;
1020                         }
1021
1022                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1023                         if (par_info != null){
1024                                 //
1025                                 // FIXME: implementing this.
1026                                 //
1027                         }
1028                         ILGenerator ig = ec.ig;
1029
1030                         ScopeInfo si;
1031                         if (ec.CurrentBlock == toplevel_owner){
1032                                 si = GetScopeFromBlock (ec, toplevel_owner);
1033                                 ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
1034                                 return;
1035                         }
1036
1037                         si = ec.CurrentAnonymousMethod.Scope;
1038                         ig.Emit (OpCodes.Ldarg_0);
1039                         if (si != null){
1040                                 while (si.ParentLink != null) {
1041                                         ig.Emit (OpCodes.Ldfld, si.ParentLink);
1042                                         si = si.ParentScope;
1043                                 }
1044                         }
1045                 }
1046
1047                 //
1048                 // Emits the code necessary to load the parameter named `name' within
1049                 // an anonymous method.
1050                 //
1051                 public void EmitParameter (EmitContext ec, string name)
1052                 {
1053                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1054                         if (cc != this){
1055                                 cc.EmitParameter (ec, name);
1056                                 return;
1057                         }
1058                         EmitParameterInstance (ec, name);
1059                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1060                         if (par_info != null){
1061                                 //
1062                                 // FIXME: implementing this.
1063                                 //
1064                         }
1065                         ec.ig.Emit (OpCodes.Ldfld, par_info.FieldBuilder);
1066                 }
1067
1068                 //
1069                 // Implements the assignment of `source' to the paramenter named `name' within
1070                 // an anonymous method.
1071                 //
1072                 public void EmitAssignParameter (EmitContext ec, string name, Expression source, bool leave_copy, bool prepare_for_load)
1073                 {
1074                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1075                         if (cc != this){
1076                                 cc.EmitAssignParameter (ec, name, source, leave_copy, prepare_for_load);
1077                                 return;
1078                         }
1079                         ILGenerator ig = ec.ig;
1080                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1081
1082                         EmitParameterInstance (ec, name);
1083                         source.Emit (ec);
1084                         if (leave_copy)
1085                                 ig.Emit (OpCodes.Dup);
1086                         ig.Emit (OpCodes.Stfld, par_info.FieldBuilder);
1087                 }
1088
1089                 //
1090                 // Emits the address for the parameter named `name' within
1091                 // an anonymous method.
1092                 //
1093                 public void EmitAddressOfParameter (EmitContext ec, string name)
1094                 {
1095                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1096                         if (cc != this){
1097                                 cc.EmitAddressOfParameter (ec, name);
1098                                 return;
1099                         }
1100                         EmitParameterInstance (ec, name);
1101                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1102                         ec.ig.Emit (OpCodes.Ldflda, par_info.FieldBuilder);
1103                 }
1104
1105                 //
1106                 // The following methods are only invoked on the host for the
1107                 // anonymous method.
1108                 //
1109                 public void EmitMethodHostInstance (EmitContext target, AnonymousMethod am)
1110                 {
1111                         ILGenerator ig = target.ig;
1112                         ScopeInfo si = am.Scope;
1113
1114                         if (si == null){
1115                                 ig.Emit (OpCodes.Ldarg_0);
1116                                 return;
1117                         }
1118
1119                         si.EmitInitScope (target);
1120                         ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
1121                 }
1122
1123                 ArrayList all_scopes = new ArrayList ();
1124
1125                 public void AddScope (ScopeInfo si)
1126                 {
1127                         all_scopes.Add (si);
1128                         toplevel_owner.RegisterCaptureContext (this);
1129                 }
1130
1131                 //
1132                 // Links any scopes that were not linked previously
1133                 //
1134                 public void AdjustScopes ()
1135                 {
1136                         foreach (ScopeInfo scope in all_scopes){
1137                                 if (scope.ParentScope != null)
1138                                         continue;
1139
1140                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
1141                                         if (scopes [b.ID] != null){
1142                                                 LinkScope (scope, b.ID);
1143                                                 break;
1144                                         }
1145                                 }
1146
1147                                 if (scope.ParentScope == null && ParentCaptureContext != null){
1148                                         CaptureContext pcc = ParentCaptureContext;
1149
1150                                         for (Block b = Host.ContainingBlock; b != null; b = b.Parent){
1151                                                 if (pcc.scopes [b.ID] != null){
1152                                                         pcc.LinkScope (scope, b.ID);
1153                                                         break;
1154                                                 }
1155                                         }
1156                                 }
1157                         }
1158                 }
1159         }
1160 }