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                 public string[] TypeParameters;
  51                 public Type[] TypeArguments;
  52                 bool unreachable;
  53
  54                 //
  55                 // The modifiers applied to the method, we aggregate them
  56                 //
  57                 int method_modifiers = Modifiers.PRIVATE;
  58
  59                 //
  60                 // During the resolve stage of the anonymous method body,
  61                 // we discover the actual scope where we are hosted, or
  62                 // null to host the method in the same class
  63                 //
  64                 public ScopeInfo Scope;
  65
  66                 //
  67                 // Points to our container anonymous method if its present
  68                 //
  69                 public AnonymousMethod ContainerAnonymousMethod;
  70
  71                 public AnonymousMethod (Parameters parameters, ToplevelBlock container, ToplevelBlock block, Location l)
  72                 {
  73                         Parameters = parameters;
  74                         Block = block;
  75                         loc = l;
  76
  77                         //
  78                         // The order is important: this setups the CaptureContext tree hierarchy.
  79                         //
  80                         container.SetHaveAnonymousMethods (l, this);
  81                         block.SetHaveAnonymousMethods (l, this);
  82                 }
  83
  84                 public override Expression DoResolve (EmitContext ec)
  85                 {
  86                         //
  87                         // Set class type, set type
  88                         //
  89
  90                         eclass = ExprClass.Value;
  91
  92                         //
  93                         // This hack means `The type is not accessible
  94                         // anywhere', we depend on special conversion
  95                         // rules.
  96                         //
  97                         type = TypeManager.anonymous_method_type;
  98
  99                         return this;
 100                 }
 101
 102                 public override void Emit (EmitContext ec)
 103                 {
 104                         // nothing, as we only exist to not do anything.
 105                 }
 106
 107                 //
 108                 // Creates the host for the anonymous method
 109                 //
 110                 bool CreateMethodHost (EmitContext ec, Type return_type)
 111                 {
 112                         //
 113                         // Crude hack follows: we replace the TypeBuilder during the
 114                         // definition to get the method hosted in the right class
 115                         //
 116
 117                         TypeBuilder current_type = ec.TypeContainer.TypeBuilder;
 118                         TypeBuilder type_host = (Scope == null ) // || Scope.ScopeTypeBuilder == null)
 119                                 ? current_type : Scope.ScopeTypeBuilder;
 120
 121                         if (current_type == null)
 122                                 throw new Exception ("The current_type is null");
 123
 124                         if (type_host == null)
 125                                 throw new Exception (String.Format ("Type host is null, Scope is {0}", Scope == null ? "null" : "Not null"));
 126
 127                         if (current_type == type_host && ec.IsStatic){
 128                                 if (ec.IsStatic){
 129                                         method_modifiers |= Modifiers.STATIC;
 130                                 }
 131                                 current_type = null;
 132                         }
 133
 134                         string name = "<#AnonymousMethod>" + anonymous_method_count++;
 135                         MemberName member_name;
 136
 137                         GenericMethod generic_method = null;
 138                         if (TypeParameters != null) {
 139                                 TypeArguments args = new TypeArguments (loc);
 140                                 foreach (string t in TypeParameters)
 141                                         args.Add (new SimpleName (t, loc));
 142
 143                                 member_name = new MemberName (name, args);
 144
 145                                 generic_method = new GenericMethod (
 146                                         ec.DeclSpace.NamespaceEntry,
 147                                         (TypeContainer) ec.TypeContainer,
 148                                         member_name, loc);
 149
 150                                 generic_method.SetParameterInfo (null);
 151                         } else
 152                                 member_name = new MemberName (name);
 153
 154                         method = new Method (
 155                                 (TypeContainer) ec.TypeContainer, generic_method,
 156                                 new TypeExpression (return_type, loc),
 157                                 method_modifiers, false, member_name,
 158                                 Parameters, null, loc);
 159                         method.Block = Block;
 160
 161                         //
 162                         // Swap the TypeBuilder while we define the method, then restore
 163                         //
 164                         if (current_type != null)
 165                                 ec.TypeContainer.TypeBuilder = type_host;
 166                         bool res = method.Define ();
 167                         if (current_type != null)
 168                                 ec.TypeContainer.TypeBuilder = current_type;
 169
 170                         return res;
 171                 }
 172
 173                 void Error_ParameterMismatch (Type t)
 174                 {
 175                         Report.Error (1661, loc, "Anonymous method could not be converted to delegate `" +
 176                                       "{0}' since there is a parameter mismatch", t);
 177         }
 178
 179                 //
 180                 // Returns true if this anonymous method can be implicitly
 181                 // converted to the delegate type `delegate_type'
 182                 //
 183                 public Expression Compatible (EmitContext ec, Type delegate_type, bool probe)
 184                 {
 185                         //
 186                         // At this point its the first time we know the return type that is
 187                         // needed for the anonymous method.  We create the method here.
 188                         //
 189
 190                         MethodGroupExpr invoke_mg = Delegate.GetInvokeMethod (ec, delegate_type, loc);
 191                         invoke_mb = (MethodInfo) invoke_mg.Methods [0];
 192                         ParameterData invoke_pd = TypeManager.GetParameterData (invoke_mb);
 193
 194                         if (delegate_type.IsGenericInstance) {
 195                                 TypeArguments = TypeManager.GetTypeArguments (delegate_type);
 196
 197                                 Type def = delegate_type.GetGenericTypeDefinition ();
 198                                 Type[] tparam = TypeManager.GetTypeArguments (def);
 199                                 TypeParameters = new string [tparam.Length];
 200                                 for (int i = 0; i < tparam.Length; i++)
 201                                         TypeParameters [i] = tparam [i].Name;
 202                         }
 203
 204                         if (Parameters == null){
 205                                 int i, j;
 206
 207                                 //
 208                                 // We provide a set of inaccessible parameters
 209                                 //
 210                                 int params_idx = -1;
 211                                 for (i = 0; i < invoke_pd.Count; i++){
 212                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 213                                                 params_idx = i;
 214                                 }
 215                                 int n = invoke_pd.Count - (params_idx != -1 ? 1 : 0);
 216                                 Parameter [] fixedpars = new Parameter [n];
 217
 218                                 for (i =  j = 0; i < invoke_pd.Count; i++){
 219                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 220                                                 continue;
 221                                         fixedpars [j] = new Parameter (
 222                                                 new TypeExpression (invoke_pd.ParameterType (i), loc),
 223                                                 "+" + j, invoke_pd.ParameterModifier (i), null);
 224                                         j++;
 225                                 }
 226
 227                                 Parameter variable = null;
 228                                 if (params_idx != -1){
 229                                         variable = new Parameter (
 230                                                 new TypeExpression (invoke_pd.ParameterType (params_idx), loc),
 231                                                 "+" + params_idx, invoke_pd.ParameterModifier (params_idx), null);
 232                                 }
 233
 234                                 Parameters = new Parameters (fixedpars, variable, loc);
 235                         }
 236
 237                         //
 238                         // First, parameter types of `delegate_type' must be compatible
 239                         // with the anonymous method.
 240                         //
 241                         amp = new InternalParameters (Parameters.GetParameterInfo (ec), Parameters);
 242
 243                         if (amp.Count != invoke_pd.Count){
 244                                 if (!probe){
 245                                         Report.Error (1593, loc,
 246                                               "Anonymous method has {0} parameters, while delegate requires {1}",
 247                                               amp.Count, invoke_pd.Count);
 248                                         Error_ParameterMismatch (delegate_type);
 249                                 }
 250                                 return null;
 251                         }
 252
 253                         for (int i = 0; i < amp.Count; i++){
 254                                 Parameter.Modifier amp_mod = amp.ParameterModifier (i);
 255
 256                                 if ((amp_mod & (Parameter.Modifier.OUT | Parameter.Modifier.REF)) != 0){
 257                                         if (!probe){
 258                                                 Error_ParameterMismatch (delegate_type);
 259                                                 Report.Error (1677, loc, "Parameter '{0}' should not be declared with the '{1}' keyword",
 260                                                         i+1, amp.ModifierDesc (i));
 261                                         }
 262                                         return null;
 263                                 }
 264
 265                                 if (amp_mod != invoke_pd.ParameterModifier (i)){
 266                                         if (!probe){
 267                                                 Report.Error (1676, loc,
 268                                                       "Signature mismatch in parameter modifier for parameter #0", i + 1);
 269                                                 Error_ParameterMismatch (delegate_type);
 270                                         }
 271                                         return null;
 272                                 }
 273
 274                                 if (amp.ParameterType (i) != invoke_pd.ParameterType (i)){
 275                                         if (!probe){
 276                                                 Report.Error (1678, loc,
 277                                                                       "Signature mismatch in parameter {0}: need `{1}' got `{2}'", i + 1,
 278                                                                       TypeManager.CSharpName (invoke_pd.ParameterType (i)),
 279                                                                       TypeManager.CSharpName (amp.ParameterType (i)));
 280                                                 Error_ParameterMismatch (delegate_type);
 281                                         }
 282                                         return null;
 283                                 }
 284                         }
 285
 286                         //
 287                         // If we are only probing, return ourselves
 288                         //
 289                         if (probe)
 290                                 return this;
 291
 292                         //
 293                         // Second: the return type of the delegate must be compatible with
 294                         // the anonymous type.   Instead of doing a pass to examine the block
 295                         // we satisfy the rule by setting the return type on the EmitContext
 296                         // to be the delegate type return type.
 297                         //
 298
 299                         //MethodBuilder builder = method_data.MethodBuilder;
 300                         //ILGenerator ig = builder.GetILGenerator ();
 301
 302
 303                         aec = new EmitContext (
 304                                 ec.TypeContainer, ec.DeclSpace, loc, null,
 305                                 invoke_mb.ReturnType,
 306                                 /* REVIEW */ (ec.InIterator ? Modifiers.METHOD_YIELDS : 0) |
 307                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0) |
 308                                 (ec.IsStatic ? Modifiers.STATIC : 0),
 309                                 /* No constructor */ false);
 310
 311                         aec.CurrentAnonymousMethod = this;
 312                         ContainerAnonymousMethod = ec.CurrentAnonymousMethod;
 313                         ContainingBlock = ec.CurrentBlock;
 314
 315                         if (aec.ResolveTopBlock (ec, Block, amp, loc, out unreachable))
 316                                 return new AnonymousDelegate (this, delegate_type, loc).Resolve (ec);
 317
 318                         return null;
 319                 }
 320
 321                 public MethodInfo GetMethodBuilder ()
 322                 {
 323                         MethodInfo builder = method.MethodData.MethodBuilder;
 324                         if (TypeArguments != null)
 325                                 return builder.BindGenericParameters (TypeArguments);
 326                         else
 327                                 return builder;
 328                 }
 329
 330                 public bool EmitMethod (EmitContext ec)
 331                 {
 332                         if (!CreateMethodHost (ec, invoke_mb.ReturnType))
 333                                 return false;
 334
 335                         MethodBuilder builder = method.MethodData.MethodBuilder;
 336                         ILGenerator ig = builder.GetILGenerator ();
 337                         aec.ig = ig;
 338
 339                         Parameters.LabelParameters (aec, builder, loc);
 340
 341                         //
 342                         // Adjust based on the computed state of the
 343                         // method from CreateMethodHost
 344
 345                         aec.MethodIsStatic = (method_modifiers & Modifiers.STATIC) != 0;
 346
 347                         aec.EmitMeta (Block, amp);
 348                         aec.EmitResolvedTopBlock (Block, unreachable);
 349                         return true;
 350                 }
 351
 352                 public static void Error_AddressOfCapturedVar (string name, Location loc)
 353                 {
 354                         Report.Error (1686, loc,
 355                                       "Variable {0} is captured in an anonymous method and its address is also being taken: they are exclusive", name);
 356                 }
 357         }
 358
 359         //
 360         // This will emit the code for the delegate, as well delegate creation on the host
 361         //
 362         public class AnonymousDelegate : DelegateCreation {
 363                 AnonymousMethod am;
 364
 365                 public AnonymousDelegate (AnonymousMethod am, Type target_type, Location l)
 366                 {
 367                         type = target_type;
 368                         loc = l;
 369                         this.am = am;
 370                 }
 371
 372                 public override Expression DoResolve (EmitContext ec)
 373                 {
 374                         eclass = ExprClass.Value;
 375
 376                         return this;
 377                 }
 378
 379                 public override void Emit (EmitContext ec)
 380                 {
 381                         if (!am.EmitMethod (ec))
 382                                 return;
 383
 384                         //
 385                         // Now emit the delegate creation.
 386                         //
 387                         if ((am.method.ModFlags & Modifiers.STATIC) == 0)
 388                                 delegate_instance_expression = new AnonymousInstance (am);
 389
 390                         Expression ml = Expression.MemberLookup (ec, type, ".ctor", loc);
 391                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 392                         delegate_method = am.GetMethodBuilder ();
 393                         base.Emit (ec);
 394                 }
 395
 396                 class AnonymousInstance : Expression {
 397                         AnonymousMethod am;
 398
 399                         public AnonymousInstance (AnonymousMethod am)
 400                         {
 401                                 this.am = am;
 402                                 eclass = ExprClass.Value;
 403                         }
 404
 405                         public override Expression DoResolve (EmitContext ec)
 406                         {
 407                                 return this;
 408                         }
 409
 410                         public override void Emit (EmitContext ec)
 411                         {
 412                                 am.aec.EmitMethodHostInstance (ec, am);
 413                         }
 414                 }
 415         }
 416
 417         class CapturedParameter {
 418                 public Type Type;
 419                 public FieldBuilder FieldBuilder;
 420                 public int Idx;
 421
 422                 public CapturedParameter (Type type, int idx)
 423                 {
 424                         Type = type;
 425                         Idx = idx;
 426                 }
 427         }
 428
 429         //
 430         // Here we cluster all the variables captured on a given scope, we also
 431         // keep some extra information that might be required on each scope.
 432         //
 433         public class ScopeInfo {
 434                 public CaptureContext CaptureContext;
 435                 public ScopeInfo ParentScope;
 436                 public Block ScopeBlock;
 437                 public bool NeedThis = false;
 438                 public bool HostsParameters = false;
 439
 440                 // For tracking the number of scopes created.
 441                 public int id;
 442                 static int count;
 443                 bool inited = false;
 444
 445                 ArrayList locals = new ArrayList ();
 446                 ArrayList children = new ArrayList ();
 447
 448                 //
 449                 // The types and fields generated
 450                 //
 451                 public TypeBuilder ScopeTypeBuilder;
 452                 public ConstructorBuilder ScopeConstructor;
 453                 public FieldBuilder THIS;
 454                 public FieldBuilder ParentLink;
 455
 456                 //
 457                 // Points to the object of type `ScopeTypeBuilder' that
 458                 // holds the data for the scope
 459                 //
 460                 public LocalBuilder ScopeInstance;
 461
 462
 463                 public ScopeInfo (CaptureContext cc, Block b)
 464                 {
 465                         CaptureContext = cc;
 466                         ScopeBlock = b;
 467                         id = count++;
 468
 469                         cc.AddScope (this);
 470                 }
 471
 472                 public void AddLocal (LocalInfo li)
 473                 {
 474                         if (locals.Contains (li))
 475                                 return;
 476
 477                         locals.Add (li);
 478 }
 479
 480                 public bool IsCaptured (LocalInfo li)
 481                 {
 482                         return locals.Contains (li);
 483                 }
 484
 485                 internal void AddChild (ScopeInfo si)
 486                 {
 487                         if (children.Contains (si))
 488                                 return;
 489
 490                         //
 491                         // If any of the current children should be a children of `si', move them there
 492                         //
 493                         ArrayList move_queue = null;
 494                         foreach (ScopeInfo child in children){
 495                                 if (child.ScopeBlock.IsChildOf (si.ScopeBlock)){
 496                                         if (move_queue == null)
 497                                                 move_queue = new ArrayList ();
 498                                         move_queue.Add (child);
 499                                         child.ParentScope = si;
 500                                         si.AddChild (child);
 501                                 }
 502                         }
 503
 504                         children.Add (si);
 505
 506                         if (move_queue != null){
 507                                 foreach (ScopeInfo child in move_queue){
 508                                         children.Remove (child);
 509                                 }
 510                         }
 511                 }
 512
 513                 static int indent = 0;
 514
 515                 void Pad ()
 516                 {
 517                         for (int i = 0; i < indent; i++)
 518                                 Console.Write ("    ");
 519                 }
 520
 521                 void EmitDebug ()
 522                 {
 523                         //Console.WriteLine (Environment.StackTrace);
 524                         Pad ();
 525                         Console.WriteLine ("START");
 526                         indent++;
 527                         Pad ();
 528                         Console.WriteLine ("NeedThis=" + NeedThis);
 529                         foreach (LocalInfo li in locals){
 530                                 Pad ();
 531                                 Console.WriteLine ("var {0}", li.Name);
 532                         }
 533
 534                         foreach (ScopeInfo si in children)
 535                                 si.EmitDebug ();
 536                         indent--;
 537                         Pad ();
 538                         Console.WriteLine ("END");
 539                 }
 540
 541                 public string MakeHelperName ()
 542                 {
 543                         return String.Format ("<>AnonHelp<{0}>", id);
 544                 }
 545
 546                 public void EmitScopeConstructor ()
 547                 {
 548                         Type [] constructor_types = TypeManager.NoTypes;
 549                         Parameters constructor_parameters = Parameters.EmptyReadOnlyParameters;
 550                         ScopeConstructor = ScopeTypeBuilder.DefineConstructor (
 551                                 MethodAttributes.Public | MethodAttributes.HideBySig |
 552                                 MethodAttributes.SpecialName | MethodAttributes.RTSpecialName,
 553                                 CallingConventions.HasThis, constructor_types);
 554                         InternalParameters parameter_info = new InternalParameters (constructor_types, constructor_parameters);
 555                         TypeManager.RegisterMethod (ScopeConstructor, parameter_info, constructor_types);
 556
 557                         ILGenerator cig = ScopeConstructor.GetILGenerator ();
 558                         cig.Emit (OpCodes.Ldarg_0);
 559                         cig.Emit (OpCodes.Call, TypeManager.object_ctor);
 560                         cig.Emit (OpCodes.Ret);
 561                 }
 562
 563                 public void EmitScopeType (EmitContext ec)
 564                 {
 565                         //EmitDebug ();
 566
 567                         if (ScopeTypeBuilder != null)
 568                                 return;
 569
 570                         TypeBuilder container = ec.TypeContainer.TypeBuilder;
 571
 572                         ScopeTypeBuilder = container.DefineNestedType (
 573                                 MakeHelperName (), TypeAttributes.AutoLayout | TypeAttributes.Class | TypeAttributes.NestedAssembly,
 574                                 TypeManager.object_type, null);
 575
 576                         if (NeedThis)
 577                                 THIS = ScopeTypeBuilder.DefineField ("<>THIS", container, FieldAttributes.Assembly);
 578
 579                         if (ParentScope != null){
 580                                 if (ParentScope.ScopeTypeBuilder == null){
 581                                         throw new Exception (String.Format ("My parent has not been initialized {0} and {1}", ParentScope, this));
 582                                 }
 583
 584                                 ParentLink = ScopeTypeBuilder.DefineField ("<>parent", ParentScope.ScopeTypeBuilder,
 585                                                                            FieldAttributes.Assembly);
 586                         }
 587
 588                         if (NeedThis && ParentScope != null)
 589                                 throw new Exception ("I was not expecting THIS && having a parent");
 590
 591                         foreach (LocalInfo info in locals){
 592                                 info.FieldBuilder = ScopeTypeBuilder.DefineField (
 593                                         info.Name, info.VariableType, FieldAttributes.Assembly);
 594                         }
 595
 596                         if (HostsParameters){
 597                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 598
 599                                 foreach (DictionaryEntry de in captured_parameters){
 600                                         string name = (string) de.Key;
 601                                         CapturedParameter cp = (CapturedParameter) de.Value;
 602                                         FieldBuilder fb;
 603
 604                                         fb = ScopeTypeBuilder.DefineField ("<p:" + name + ">", cp.Type, FieldAttributes.Assembly);
 605                                         cp.FieldBuilder = fb;
 606                                 }
 607                         }
 608
 609                         EmitScopeConstructor ();
 610                         foreach (ScopeInfo si in children){
 611                                 si.EmitScopeType (ec);
 612                         }
 613                 }
 614
 615                 public void CloseTypes ()
 616                 {
 617                         RootContext.RegisterCompilerGeneratedType (ScopeTypeBuilder);
 618                         foreach (ScopeInfo si in children)
 619                                 si.CloseTypes ();
 620                 }
 621
 622                 //
 623                 // Emits the initialization code for the scope
 624                 //
 625                 public void EmitInitScope (EmitContext ec)
 626                 {
 627                         ILGenerator ig = ec.ig;
 628
 629                         if (inited)
 630                                 return;
 631
 632                         if (ScopeConstructor == null)
 633                                 throw new Exception ("ScopeConstructor is null for" + this.ToString ());
 634
 635                         ig.Emit (OpCodes.Newobj, (ConstructorInfo) ScopeConstructor);
 636                         ScopeInstance = ig.DeclareLocal (ScopeTypeBuilder);
 637                         ig.Emit (OpCodes.Stloc, ScopeInstance);
 638
 639                         if (THIS != null){
 640                                 ig.Emit (OpCodes.Ldloc, ScopeInstance);
 641                                 ig.Emit (OpCodes.Ldarg_0);
 642                                 ig.Emit (OpCodes.Stfld, THIS);
 643                         }
 644
 645                         //
 646                         // Copy the parameter values, if any
 647                         //
 648                         int extra = ec.IsStatic ? 0 : 1;
 649                         if (HostsParameters){
 650                                 Hashtable captured_parameters = CaptureContext.captured_parameters;
 651
 652                                 foreach (DictionaryEntry de in captured_parameters){
 653                                         CapturedParameter cp = (CapturedParameter) de.Value;
 654
 655                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 656                                         ParameterReference.EmitLdArg (ig, cp.Idx + extra);
 657                                         ig.Emit (OpCodes.Stfld, cp.FieldBuilder);
 658                                 }
 659                         }
 660
 661                         if (ParentScope != null){
 662                                 if (!ParentScope.inited)
 663                                         ParentScope.EmitInitScope (ec);
 664
 665                                 //
 666                                 // Only emit initialization in our capturecontext world
 667                                 //
 668                                 if (ParentScope.CaptureContext == CaptureContext){
 669                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 670                                         ig.Emit (OpCodes.Ldloc, ParentScope.ScopeInstance);
 671                                         ig.Emit (OpCodes.Stfld, ParentLink);
 672                                 } else {
 673                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 674                                         ig.Emit (OpCodes.Ldarg_0);
 675                                         ig.Emit (OpCodes.Stfld, ParentLink);
 676                                 }
 677                         }
 678                         inited = true;
 679                 }
 680
 681                 static void DoPath (StringBuilder sb, ScopeInfo start)
 682                 {
 683                         if (start.ParentScope != null){
 684                                 DoPath (sb, start.ParentScope);
 685                                 sb.Append (", ");
 686                         }
 687                         sb.Append ((start.id).ToString ());
 688                 }
 689
 690                 public override string ToString ()
 691                 {
 692                         StringBuilder sb = new StringBuilder ();
 693
 694                         sb.Append ("{");
 695                         if (CaptureContext != null){
 696                                 sb.Append (CaptureContext.ToString ());
 697                                 sb.Append (":");
 698                         }
 699
 700                         DoPath (sb, this);
 701                         sb.Append ("}");
 702
 703                         return sb.ToString ();
 704                 }
 705         }
 706
 707         //
 708         // CaptureContext objects are created on demand if a method has
 709         // anonymous methods and kept on the ToplevelBlock.
 710         //
 711         // If they exist, all ToplevelBlocks in the containing block are
 712         // linked together (children pointing to their parents).
 713         //
 714         public class CaptureContext {
 715                 public static int count;
 716                 public int cc_id;
 717                 public Location loc;
 718
 719                 //
 720                 // Points to the toplevel block that owns this CaptureContext
 721                 //
 722                 ToplevelBlock toplevel_owner;
 723                 Hashtable scopes = new Hashtable ();
 724                 bool have_captured_vars = false;
 725                 bool referenced_this = false;
 726                 ScopeInfo topmost = null;
 727
 728                 //
 729                 // Captured fields
 730                 //
 731                 Hashtable captured_fields = new Hashtable ();
 732                 Hashtable captured_variables = new Hashtable ();
 733                 public Hashtable captured_parameters = new Hashtable ();
 734                 public AnonymousMethod Host;
 735
 736                 public CaptureContext (ToplevelBlock toplevel_owner, Location loc, AnonymousMethod host)
 737                 {
 738                         cc_id = count++;
 739                         this.toplevel_owner = toplevel_owner;
 740                         this.loc = loc;
 741
 742                         if (host != null)
 743                                 Host = host;
 744                 }
 745
 746                 void DoPath (StringBuilder sb, CaptureContext cc)
 747                 {
 748                         if (cc.ParentCaptureContext != null){
 749                                 DoPath (sb, cc.ParentCaptureContext);
 750                                 sb.Append (".");
 751                         }
 752                         sb.Append (cc_id.ToString ());
 753                 }
 754
 755                 public override string ToString ()
 756                 {
 757                         StringBuilder sb = new StringBuilder ();
 758                         sb.Append ("[");
 759                         DoPath (sb, this);
 760                         sb.Append ("]");
 761                         return sb.ToString ();
 762                 }
 763
 764                 public ToplevelBlock ParentToplevel {
 765                         get {
 766                                 return toplevel_owner.Container;
 767                         }
 768                 }
 769
 770                 public CaptureContext ParentCaptureContext {
 771                         get {
 772                                 ToplevelBlock parent = ParentToplevel;
 773
 774                                 return (parent == null) ? null : parent.CaptureContext;
 775                         }
 776                 }
 777
 778                 // Returns the deepest of two scopes
 779                 public ScopeInfo Deepest (ScopeInfo a, ScopeInfo b)
 780                 {
 781                         ScopeInfo p;
 782
 783                         if (a == null)
 784                                 return b;
 785                         if (b == null)
 786                                 return a;
 787                         if (a == b)
 788                                 return a;
 789
 790                         //
 791                         // If they Scopes are on the same CaptureContext, we do the double
 792                         // checks just so if there is an invariant change in the future,
 793                         // we get the exception at the end
 794                         //
 795                         for (p = a; p != null; p = p.ParentScope)
 796                                 if (p == b)
 797                                         return a;
 798
 799                         for (p = b; p != null; p = p.ParentScope)
 800                                 if (p == a)
 801                                         return b;
 802
 803                         CaptureContext ca = a.CaptureContext;
 804                         CaptureContext cb = b.CaptureContext;
 805
 806                         for (CaptureContext c = ca; c != null; c = c.ParentCaptureContext)
 807                                 if (c == cb)
 808                                         return a;
 809
 810                         for (CaptureContext c = cb; c != null; c = c.ParentCaptureContext)
 811                                 if (c == ca)
 812                                         return b;
 813                         throw new Exception ("Should never be reached");
 814                 }
 815
 816                 void AdjustMethodScope (AnonymousMethod am, ScopeInfo scope)
 817                 {
 818                         am.Scope = Deepest (am.Scope, scope);
 819                 }
 820
 821                 void LinkScope (ScopeInfo scope, int id)
 822                 {
 823                         ScopeInfo parent = (ScopeInfo) scopes [id];
 824                         scope.ParentScope = parent;
 825                         parent.AddChild (scope);
 826
 827                         if (scope == topmost)
 828                                 topmost = parent;
 829                 }
 830
 831                 public void AddLocal (AnonymousMethod am, LocalInfo li)
 832                 {
 833                         if (li.Block.Toplevel != toplevel_owner){
 834                                 ParentCaptureContext.AddLocal (am, li);
 835                                 return;
 836                         }
 837                         int block_id = li.Block.ID;
 838                         ScopeInfo scope;
 839                         if (scopes [block_id] == null){
 840                                 scope = new ScopeInfo (this, li.Block);
 841                                 scopes [block_id] = scope;
 842                         } else
 843                                 scope = (ScopeInfo) scopes [block_id];
 844
 845                         if (topmost == null){
 846                                 topmost = scope;
 847                         } else {
 848                                 // Link to parent
 849
 850                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
 851                                         if (scopes [b.ID] != null){
 852                                                 LinkScope (scope, b.ID);
 853                                                 break;
 854                                         }
 855                                 }
 856
 857                                 if (scope.ParentScope == null && ParentCaptureContext != null){
 858                                         CaptureContext pcc = ParentCaptureContext;
 859
 860                                         for (Block b = am.ContainingBlock; b != null; b = b.Parent){
 861                                                 if (pcc.scopes [b.ID] != null){
 862                                                         pcc.LinkScope (scope, b.ID);
 863                                                         break;
 864                                                 }
 865                                         }
 866                                 }
 867                         }
 868
 869                         //
 870                         // Adjust the owner
 871                         //
 872                         if (Host != null)
 873                                 AdjustMethodScope (Host, topmost);
 874
 875                         //
 876                         // Adjust the user
 877                         //
 878                         AdjustMethodScope (am, scope);
 879
 880                         if (captured_variables [li] != null)
 881                                 return;
 882
 883                         have_captured_vars = true;
 884                         captured_variables [li] = li;
 885                         scope.AddLocal (li);
 886                 }
 887
 888                 //
 889                 // Retursn the CaptureContext for the block that defines the parameter `name'
 890                 //
 891                 static CaptureContext _ContextForParameter (ToplevelBlock current, string name)
 892                 {
 893                         ToplevelBlock container = current.Container;
 894                         if (container != null){
 895                                 CaptureContext cc = _ContextForParameter (container, name);
 896                                 if (cc != null)
 897                                         return cc;
 898                         }
 899                         if (current.IsParameterReference (name))
 900                                 return current.ToplevelBlockCaptureContext;
 901                         return null;
 902                 }
 903
 904                 static CaptureContext ContextForParameter (ToplevelBlock current, string name)
 905                 {
 906                         CaptureContext cc = _ContextForParameter (current, name);
 907                         if (cc == null)
 908                                 throw new Exception (String.Format ("request for parameteter {0} failed: not found", name));
 909                         return cc;
 910                 }
 911
 912                 //
 913                 // Records the captured parameter at the appropriate CaptureContext
 914                 //
 915                 public void AddParameter (EmitContext ec, AnonymousMethod am, string name, Type t, int idx)
 916                 {
 917                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
 918
 919                         cc.AddParameterToContext (am, name, t, idx);
 920                 }
 921
 922                 //
 923                 // Records the parameters in the context
 924                 //
 925                 void AddParameterToContext (AnonymousMethod am, string name, Type t, int idx)
 926                 {
 927                         if (captured_parameters == null)
 928                                 captured_parameters = new Hashtable ();
 929                         if (captured_parameters [name] != null)
 930                                 return;
 931                         captured_parameters [name] = new CapturedParameter (t, idx);
 932
 933                         if (topmost == null){
 934                                 //
 935                                 // Create one ScopeInfo, if there are none.
 936                                 //
 937                                 topmost = new ScopeInfo (this, toplevel_owner);
 938                                 scopes [toplevel_owner.ID] = topmost;
 939                         } else {
 940                                 //
 941                                 // If the topmost ScopeInfo is not at the topblock level, insert
 942                                 // a new ScopeInfo there.
 943                                 //
 944                                 // FIXME: This code probably should be evolved to be like the code
 945                                 // in AddLocal
 946                                 //
 947                                 if (topmost.ScopeBlock != toplevel_owner){
 948                                         ScopeInfo par_si = new ScopeInfo (this, toplevel_owner);
 949                                         ScopeInfo old_top = topmost;
 950                                         scopes [toplevel_owner.ID] = topmost;
 951                                         topmost.ParentScope = par_si;
 952                                         topmost = par_si;
 953                                         topmost.AddChild (old_top);
 954                                 }
 955                         }
 956
 957                         topmost.HostsParameters = true;
 958                         AdjustMethodScope (am, topmost);
 959                 }
 960
 961                 //
 962                 // Captured fields are only recorded on the topmost CaptureContext, because that
 963                 // one is the one linked to the owner of instance fields
 964                 //
 965                 public void AddField (FieldExpr fe)
 966                 {
 967                         if (fe.FieldInfo.IsStatic)
 968                                 throw new Exception ("Attempt to register a static field as a captured field");
 969
 970                         CaptureContext parent = ParentCaptureContext;
 971                         if (parent != null)
 972                                 parent.AddField (fe);
 973                         else
 974                                 captured_fields [fe] = fe;
 975                 }
 976
 977                 public void CaptureThis ()
 978                 {
 979                         CaptureContext parent = ParentCaptureContext;
 980                         if (parent != null)
 981                                 parent.CaptureThis ();
 982                         referenced_this = true;
 983                 }
 984
 985                 public bool HaveCapturedVariables {
 986                         get {
 987                                 return have_captured_vars;
 988                         }
 989                 }
 990
 991                 public bool HaveCapturedFields {
 992                         get {
 993                                 CaptureContext parent = ParentCaptureContext;
 994                                 if (parent != null)
 995                                         return parent.HaveCapturedFields;
 996                                 return captured_fields.Count > 0;
 997                         }
 998                 }
 999
1000                 public bool IsCaptured (LocalInfo local)
1001                 {
1002                         foreach (ScopeInfo si in scopes.Values){
1003                                 if (si.IsCaptured (local))
1004                                         return true;
1005                         }
1006                         return false;
1007                 }
1008
1009                 //
1010                 // Returns whether the parameter is captured
1011                 //
1012                 public bool IsParameterCaptured (string name)
1013                 {
1014                         if (ParentCaptureContext != null && ParentCaptureContext.IsParameterCaptured (name))
1015                                 return true;
1016
1017                         if (captured_parameters != null)
1018                                 return captured_parameters [name] != null;
1019                         return false;
1020                 }
1021
1022                 public void EmitAnonymousHelperClasses (EmitContext ec)
1023                 {
1024                         if (topmost != null){
1025                                 topmost.NeedThis = HaveCapturedFields || referenced_this;
1026                                 topmost.EmitScopeType (ec);
1027                         }
1028                 }
1029
1030                 public void CloseAnonymousHelperClasses ()
1031                 {
1032                         if (topmost != null)
1033                                 topmost.CloseTypes ();
1034                 }
1035
1036                 ScopeInfo GetScopeFromBlock (EmitContext ec, Block b)
1037                 {
1038                         ScopeInfo si;
1039
1040                         si = (ScopeInfo) scopes [b.ID];
1041                         if (si == null)
1042                                 throw new Exception ("Si is null for block " + b.ID);
1043                         si.EmitInitScope (ec);
1044
1045                         return si;
1046                 }
1047
1048                 //
1049                 // Emits the opcodes necessary to load the instance of the captured
1050                 // variable in `li'
1051                 //
1052                 public void EmitCapturedVariableInstance (EmitContext ec, LocalInfo li, AnonymousMethod am)
1053                 {
1054                         ILGenerator ig = ec.ig;
1055                         ScopeInfo si;
1056
1057                         if (li.Block.Toplevel == toplevel_owner){
1058                                 si = GetScopeFromBlock (ec, li.Block);
1059                                 ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
1060                                 return;
1061                         }
1062
1063                         si = am.Scope;
1064                         ig.Emit (OpCodes.Ldarg_0);
1065                         if (si != null){
1066                                 while (si.ScopeBlock.ID != li.Block.ID){
1067                                         if (si.ParentLink != null)
1068                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
1069                                         si = si.ParentScope;
1070                                         if (si == null) {
1071                                                 si = am.Scope;
1072                                                 Console.WriteLine ("Target: {0} {1}", li.Block.ID, li.Name);
1073                                                 while (si.ScopeBlock.ID != li.Block.ID){
1074                                                         Console.WriteLine ("Trying: {0}", si.ScopeBlock.ID);
1075                                                         si = si.ParentScope;
1076                                                 }
1077
1078                                                 throw new Exception (
1079                                                              String.Format ("Never found block {0} starting at {1} while looking up {2}",
1080                                                                             li.Block.ID, am.Scope.ScopeBlock.ID, li.Name));
1081                                         }
1082                                 }
1083                         }
1084                 }
1085
1086                 //
1087                 // Internal routine that loads the instance to reach parameter `name'
1088                 //
1089                 void EmitParameterInstance (EmitContext ec, string name)
1090                 {
1091                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1092                         if (cc != this){
1093                                 cc.EmitParameterInstance (ec, name);
1094                                 return;
1095                         }
1096
1097                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1098                         if (par_info != null){
1099                                 //
1100                                 // FIXME: implementing this.
1101                                 //
1102                         }
1103                         ILGenerator ig = ec.ig;
1104
1105                         ScopeInfo si;
1106
1107                         if (ec.CurrentBlock.Toplevel == toplevel_owner){
1108                                 si = GetScopeFromBlock (ec, toplevel_owner);
1109                                 ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
1110                                 return;
1111                         }
1112
1113                         si = ec.CurrentAnonymousMethod.Scope;
1114                         ig.Emit (OpCodes.Ldarg_0);
1115                         if (si != null){
1116                                 while (si.ParentLink != null) {
1117                                         ig.Emit (OpCodes.Ldfld, si.ParentLink);
1118                                         si = si.ParentScope;
1119                                 }
1120                         }
1121                 }
1122
1123                 //
1124                 // Emits the code necessary to load the parameter named `name' within
1125                 // an anonymous method.
1126                 //
1127                 public void EmitParameter (EmitContext ec, string name)
1128                 {
1129                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1130                         if (cc != this){
1131                                 cc.EmitParameter (ec, name);
1132                                 return;
1133                         }
1134                         EmitParameterInstance (ec, name);
1135                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1136                         if (par_info != null){
1137                                 //
1138                                 // FIXME: implementing this.
1139                                 //
1140                         }
1141                         ec.ig.Emit (OpCodes.Ldfld, par_info.FieldBuilder);
1142                 }
1143
1144                 //
1145                 // Implements the assignment of `source' to the paramenter named `name' within
1146                 // an anonymous method.
1147                 //
1148                 public void EmitAssignParameter (EmitContext ec, string name, Expression source, bool leave_copy, bool prepare_for_load)
1149                 {
1150                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1151                         if (cc != this){
1152                                 cc.EmitAssignParameter (ec, name, source, leave_copy, prepare_for_load);
1153                                 return;
1154                         }
1155                         ILGenerator ig = ec.ig;
1156                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1157
1158                         EmitParameterInstance (ec, name);
1159                         source.Emit (ec);
1160                         if (leave_copy)
1161                                 ig.Emit (OpCodes.Dup);
1162                         ig.Emit (OpCodes.Stfld, par_info.FieldBuilder);
1163                 }
1164
1165                 //
1166                 // Emits the address for the parameter named `name' within
1167                 // an anonymous method.
1168                 //
1169                 public void EmitAddressOfParameter (EmitContext ec, string name)
1170                 {
1171                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1172                         if (cc != this){
1173                                 cc.EmitAddressOfParameter (ec, name);
1174                                 return;
1175                         }
1176                         EmitParameterInstance (ec, name);
1177                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1178                         ec.ig.Emit (OpCodes.Ldflda, par_info.FieldBuilder);
1179                 }
1180
1181                 //
1182                 // The following methods are only invoked on the host for the
1183                 // anonymous method.
1184                 //
1185                 public void EmitMethodHostInstance (EmitContext target, AnonymousMethod am)
1186                 {
1187                         ILGenerator ig = target.ig;
1188                         ScopeInfo si = am.Scope;
1189
1190                         if (si == null){
1191                                 ig.Emit (OpCodes.Ldarg_0);
1192                                 return;
1193                         }
1194
1195                         si.EmitInitScope (target);
1196                         ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
1197                 }
1198
1199                 ArrayList all_scopes = new ArrayList ();
1200
1201                 public void AddScope (ScopeInfo si)
1202                 {
1203                         all_scopes.Add (si);
1204                         toplevel_owner.RegisterCaptureContext (this);
1205                 }
1206
1207                 //
1208                 // Links any scopes that were not linked previously
1209                 //
1210                 public void AdjustScopes ()
1211                 {
1212                         foreach (ScopeInfo scope in all_scopes){
1213                                 if (scope.ParentScope != null)
1214                                         continue;
1215
1216                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
1217                                         if (scopes [b.ID] != null){
1218                                                 LinkScope (scope, b.ID);
1219                                                 break;
1220                                         }
1221                                 }
1222
1223                                 if (scope.ParentScope == null && ParentCaptureContext != null){
1224                                         CaptureContext pcc = ParentCaptureContext;
1225
1226                                         for (Block b = Host.ContainingBlock; b != null; b = b.Parent){
1227                                                 if (pcc.scopes [b.ID] != null){
1228                                                         pcc.LinkScope (scope, b.ID);
1229                                                         break;
1230                                                 }
1231                                         }
1232                                 }
1233                         }
1234                 }
1235         }
1236 }