mcs/mcs/anonymous.cs

   1 //
   2 // anonymous.cs: Support for anonymous methods
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximain.com)
   6 //
   7 // (C) 2003, 2004 Novell, Inc.
   8 //
   9 // TODO: Ideally, we should have the helper classes emited as a hierarchy to map
  10 // their nesting, and have the visibility set to private, instead of NestedAssembly
  11 //
  12 //
  13 //
  14
  15 using System;
  16 using System.Text;
  17 using System.Collections;
  18 using System.Reflection;
  19 using System.Reflection.Emit;
  20
  21 namespace Mono.CSharp {
  22
  23         public class AnonymousMethod : Expression {
  24                 // Used to generate unique method names.
  25                 static int anonymous_method_count;
  26
  27                 // An array list of AnonymousMethodParameter or null
  28                 public Parameters Parameters;
  29
  30                 //
  31                 // The block that makes up the body for the anonymous mehtod
  32                 //
  33                 public ToplevelBlock Block;
  34
  35                 //
  36                 // The container block for this anonymous method.
  37                 //
  38                 public Block ContainingBlock;
  39
  40                 //
  41                 // The implicit method we create
  42                 //
  43                 public Method method;
  44
  45                 MethodInfo invoke_mb;
  46
  47                 // The emit context for the anonymous method
  48                 public EmitContext aec;
  49                 public InternalParameters amp;
  50                 bool unreachable;
  51
  52                 //
  53                 // The modifiers applied to the method, we aggregate them
  54                 //
  55                 int method_modifiers = Modifiers.INTERNAL;
  56
  57                 //
  58                 // During the resolve stage of the anonymous method body,
  59                 // we discover the actual scope where we are hosted, or
  60                 // null to host the method in the same class
  61                 //
  62                 public ScopeInfo Scope;
  63
  64                 //
  65                 // Points to our container anonymous method if its present
  66                 //
  67                 public AnonymousMethod ContainerAnonymousMethod;
  68
  69                 public AnonymousMethod (Parameters parameters, ToplevelBlock container, ToplevelBlock block, Location l)
  70                 {
  71                         Parameters = parameters;
  72                         Block = block;
  73                         loc = l;
  74
  75                         //
  76                         // The order is important: this setups the CaptureContext tree hierarchy.
  77                         //
  78                         container.SetHaveAnonymousMethods (l, this);
  79                         block.SetHaveAnonymousMethods (l, this);
  80                 }
  81
  82                 public override Expression DoResolve (EmitContext ec)
  83                 {
  84                         //
  85                         // Set class type, set type
  86                         //
  87
  88                         eclass = ExprClass.Value;
  89
  90                         //
  91                         // This hack means `The type is not accessible
  92                         // anywhere', we depend on special conversion
  93                         // rules.
  94                         //
  95                         type = TypeManager.anonymous_method_type;
  96
  97                         return this;
  98                 }
  99
 100                 public override void Emit (EmitContext ec)
 101                 {
 102                         // nothing, as we only exist to not do anything.
 103                 }
 104
 105                 //
 106                 // Creates the host for the anonymous method
 107                 //
 108                 bool CreateMethodHost (EmitContext ec, Type return_type)
 109                 {
 110                         //
 111                         // Crude hack follows: we replace the TypeBuilder during the
 112                         // definition to get the method hosted in the right class
 113                         //
 114
 115                         TypeBuilder current_type = ec.TypeContainer.TypeBuilder;
 116                         TypeBuilder type_host = Scope == null ? current_type : Scope.ScopeTypeBuilder;
 117
 118                         if (current_type == null)
 119                                 throw new Exception ("The current_type is null");
 120
 121                         if (type_host == null)
 122                                 throw new Exception ("Type host is null");
 123
 124                         if (current_type == type_host && ec.IsStatic){
 125                                 if (ec.IsStatic)
 126                                         method_modifiers |= Modifiers.STATIC;
 127                                 current_type = null;
 128                         }
 129
 130                         method = new Method (
 131                                 (TypeContainer) ec.TypeContainer,
 132                                 new TypeExpression (return_type, loc),
 133                                 method_modifiers, false, new MemberName ("<#AnonymousMethod>" + anonymous_method_count++),
 134                                 Parameters, null, loc);
 135                         method.Block = Block;
 136
 137
 138                         //
 139                         // Swap the TypeBuilder while we define the method, then restore
 140                         //
 141                         if (current_type != null)
 142                                 ec.TypeContainer.TypeBuilder = type_host;
 143                         bool res = method.Define ();
 144                         if (current_type != null)
 145                                 ec.TypeContainer.TypeBuilder = current_type;
 146                         return res;
 147                 }
 148
 149                 void Error_ParameterMismatch (Type t)
 150                 {
 151                         Report.Error (1661, loc, "Anonymous method could not be converted to delegate `" +
 152                                       "{0}' since there is a parameter mismatch", t);
 153                 }
 154
 155                 //
 156                 // Returns true if this anonymous method can be implicitly
 157                 // converted to the delegate type `delegate_type'
 158                 //
 159                 public Expression Compatible (EmitContext ec, Type delegate_type, bool probe)
 160                 {
 161                         //
 162                         // At this point its the first time we know the return type that is
 163                         // needed for the anonymous method.  We create the method here.
 164                         //
 165
 166                         invoke_mb = (MethodInfo) Delegate.GetInvokeMethod (ec, delegate_type, loc);
 167                         ParameterData invoke_pd = Invocation.GetParameterData (invoke_mb);
 168
 169                         //
 170                         // If implicit parameters are set, then we must check for out in the parameters
 171                         // and flag it accordingly.
 172                         //
 173                         bool out_invalid_check = false;
 174
 175                         if (Parameters == null){
 176                                 int i, j;
 177                                 out_invalid_check = true;
 178
 179                                 //
 180                                 // We provide a set of inaccessible parameters
 181                                 //
 182                                 int params_idx = -1;
 183                                 for (i = 0; i < invoke_pd.Count; i++){
 184                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 185                                                 params_idx = i;
 186                                 }
 187                                 int n = invoke_pd.Count - (params_idx != -1 ? 1 : 0);
 188                                 Parameter [] fixedpars = new Parameter [n];
 189
 190                                 for (i =  j = 0; i < invoke_pd.Count; i++){
 191                                         if (invoke_pd.ParameterModifier (i) == Parameter.Modifier.PARAMS)
 192                                                 continue;
 193                                         fixedpars [j] = new Parameter (
 194                                                 new TypeExpression (invoke_pd.ParameterType (i), loc),
 195                                                 "+" + j, invoke_pd.ParameterModifier (i), null);
 196                                         j++;
 197                                 }
 198
 199                                 Parameter variable = null;
 200                                 if (params_idx != -1){
 201                                         variable = new Parameter (
 202                                                 new TypeExpression (invoke_pd.ParameterType (params_idx), loc),
 203                                                 "+" + params_idx, invoke_pd.ParameterModifier (params_idx), null);
 204                                 }
 205
 206                                 Parameters = new Parameters (fixedpars, variable, loc);
 207                         }
 208
 209                         //
 210                         // First, parameter types of `delegate_type' must be compatible
 211                         // with the anonymous method.
 212                         //
 213                         amp = new InternalParameters (Parameters.GetParameterInfo (ec), Parameters);
 214
 215                         if (amp.Count != invoke_pd.Count){
 216                                 if (!probe){
 217                                         Report.Error (1593, loc,
 218                                               "Anonymous method has {0} parameters, while delegate requires {1}",
 219                                               amp.Count, invoke_pd.Count);
 220                                         Error_ParameterMismatch (delegate_type);
 221                                 }
 222                                 return null;
 223                         }
 224
 225                         for (int i = 0; i < amp.Count; i++){
 226                                 Parameter.Modifier amp_mod = amp.ParameterModifier (i);
 227                                 if (amp_mod != invoke_pd.ParameterModifier (i)){
 228                                         if (!probe){
 229                                                 Report.Error (1676, loc,
 230                                                       "Signature mismatch in parameter modifier for parameter #0", i + 1);
 231                                                 Error_ParameterMismatch (delegate_type);
 232                                         }
 233                                         return null;
 234                                 }
 235
 236                                 if (amp.ParameterType (i) != invoke_pd.ParameterType (i)){
 237                                         if (!probe){
 238                                                 Report.Error (1678, loc,
 239                                                                       "Signature mismatch in parameter {0}: need `{1}' got `{2}'", i + 1,
 240                                                                       TypeManager.CSharpName (invoke_pd.ParameterType (i)),
 241                                                                       TypeManager.CSharpName (amp.ParameterType (i)));
 242                                                 Error_ParameterMismatch (delegate_type);
 243                                         }
 244                                         return null;
 245                                 }
 246
 247                                 if (out_invalid_check && (invoke_pd.ParameterModifier (i) & Parameter.Modifier.OUT) != 0){
 248                                         if (!probe){
 249                                                 Report.Error (1676, loc,"Parameter {0} must include the `out' modifier ", i+1);
 250                                                 Error_ParameterMismatch (delegate_type);
 251                                         }
 252                                         return null;
 253                                 }
 254                         }
 255
 256                         //
 257                         // If we are only probing, return ourselves
 258                         //
 259                         if (probe)
 260                                 return this;
 261
 262                         //
 263                         // Second: the return type of the delegate must be compatible with
 264                         // the anonymous type.   Instead of doing a pass to examine the block
 265                         // we satisfy the rule by setting the return type on the EmitContext
 266                         // to be the delegate type return type.
 267                         //
 268
 269                         //MethodBuilder builder = method_data.MethodBuilder;
 270                         //ILGenerator ig = builder.GetILGenerator ();
 271
 272
 273                         aec = new EmitContext (
 274                                 ec.TypeContainer, ec.DeclSpace, loc, null,
 275                                 invoke_mb.ReturnType,
 276                                 /* REVIEW */ (ec.InIterator ? Modifiers.METHOD_YIELDS : 0) |
 277                                 (ec.InUnsafe ? Modifiers.UNSAFE : 0),
 278                                 /* No constructor */ false);
 279
 280                         aec.CurrentAnonymousMethod = this;
 281                         ContainerAnonymousMethod = ec.CurrentAnonymousMethod;
 282                         ContainingBlock = ec.CurrentBlock;
 283
 284                         if (aec.ResolveTopBlock (ec, Block, amp, loc, out unreachable))
 285                                 return new AnonymousDelegate (this, delegate_type, loc).Resolve (ec);
 286
 287                         return null;
 288                 }
 289
 290                 public MethodBuilder GetMethodBuilder ()
 291                 {
 292                         return method.MethodData.MethodBuilder;
 293                 }
 294
 295                 public void EmitMethod (EmitContext ec)
 296                 {
 297                         if (!CreateMethodHost (ec, invoke_mb.ReturnType))
 298                                 return;
 299
 300                         MethodBuilder builder = GetMethodBuilder ();
 301                         ILGenerator ig = builder.GetILGenerator ();
 302                         aec.ig = ig;
 303
 304                         Parameters.LabelParameters (aec, builder, loc);
 305
 306                         //
 307                         // Adjust based on the computed state of the
 308                         // method from CreateMethodHost
 309
 310                         if ((method_modifiers & Modifiers.STATIC) != 0)
 311                                 aec.IsStatic = true;
 312
 313                         aec.EmitMeta (Block, amp);
 314                         aec.EmitResolvedTopBlock (Block, unreachable);
 315                 }
 316
 317                 public static void Error_AddressOfCapturedVar (string name, Location loc)
 318                 {
 319                         Report.Error (1686, loc,
 320                                       "Variable {0} is captured in an anonymous method and its address is also being taken: they are exclusive", name);
 321                 }
 322         }
 323
 324         //
 325         // This will emit the code for the delegate, as well delegate creation on the host
 326         //
 327         public class AnonymousDelegate : DelegateCreation {
 328                 AnonymousMethod am;
 329
 330                 public AnonymousDelegate (AnonymousMethod am, Type target_type, Location l)
 331                 {
 332                         type = target_type;
 333                         loc = l;
 334                         this.am = am;
 335                 }
 336
 337                 public override Expression DoResolve (EmitContext ec)
 338                 {
 339                         eclass = ExprClass.Value;
 340                         return this;
 341                 }
 342
 343                 public override void Emit (EmitContext ec)
 344                 {
 345                         am.EmitMethod (ec);
 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.RegisterHelperClass (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                                         string name = (string) de.Key;
 593                                         CapturedParameter cp = (CapturedParameter) de.Value;
 594
 595                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 596                                         ParameterReference.EmitLdArg (ig, cp.Idx + extra);
 597                                         ig.Emit (OpCodes.Stfld, cp.FieldBuilder);
 598                                 }
 599                         }
 600
 601                         if (ParentScope != null){
 602                                 //
 603                                 // Only emit initialization in our capturecontext world
 604                                 //
 605                                 if (ParentScope.CaptureContext == CaptureContext){
 606                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 607                                         ig.Emit (OpCodes.Ldloc, ParentScope.ScopeInstance);
 608                                         ig.Emit (OpCodes.Stfld, ParentLink);
 609                                 } else {
 610                                         ig.Emit (OpCodes.Ldloc, ScopeInstance);
 611                                         ig.Emit (OpCodes.Ldarg_0);
 612                                         ig.Emit (OpCodes.Stfld, ParentLink);
 613                                 }
 614                         }
 615                         inited = true;
 616                 }
 617
 618                 static void DoPath (StringBuilder sb, ScopeInfo start)
 619                 {
 620                         if (start.ParentScope != null){
 621                                 DoPath (sb, start.ParentScope);
 622                                 sb.Append (", ");
 623                         }
 624                         sb.Append ((start.id).ToString ());
 625                 }
 626
 627                 public override string ToString ()
 628                 {
 629                         StringBuilder sb = new StringBuilder ();
 630
 631                         sb.Append ("{");
 632                         if (CaptureContext != null){
 633                                 sb.Append (CaptureContext.ToString ());
 634                                 sb.Append (":");
 635                         }
 636
 637                         DoPath (sb, this);
 638                         sb.Append ("}");
 639
 640                         return sb.ToString ();
 641                 }
 642         }
 643
 644         //
 645         // CaptureContext objects are created on demand if a method has
 646         // anonymous methods and kept on the ToplevelBlock.
 647         //
 648         // If they exist, all ToplevelBlocks in the containing block are
 649         // linked together (children pointing to their parents).
 650         //
 651         public class CaptureContext {
 652                 public static int count;
 653                 public int cc_id;
 654                 Location loc;
 655
 656                 //
 657                 // Points to the toplevel block that owns this CaptureContext
 658                 //
 659                 ToplevelBlock toplevel_owner;
 660                 Hashtable scopes = new Hashtable ();
 661                 bool have_captured_vars = false;
 662                 ScopeInfo topmost = null;
 663
 664                 //
 665                 // Captured fields
 666                 //
 667                 Hashtable captured_fields = new Hashtable ();
 668                 Hashtable captured_variables = new Hashtable ();
 669                 public Hashtable captured_parameters = new Hashtable ();
 670                 public AnonymousMethod Host;
 671
 672                 public CaptureContext (ToplevelBlock toplevel_owner, Location loc, AnonymousMethod host)
 673                 {
 674                         cc_id = count++;
 675                         this.toplevel_owner = toplevel_owner;
 676                         this.loc = loc;
 677
 678                         if (host != null)
 679                                 Host = host;
 680                 }
 681
 682                 void DoPath (StringBuilder sb, CaptureContext cc)
 683                 {
 684                         if (cc.ParentCaptureContext != null){
 685                                 DoPath (sb, cc.ParentCaptureContext);
 686                                 sb.Append (".");
 687                         }
 688                         sb.Append (cc_id.ToString ());
 689                 }
 690
 691                 public override string ToString ()
 692                 {
 693                         StringBuilder sb = new StringBuilder ();
 694                         sb.Append ("[");
 695                         DoPath (sb, this);
 696                         sb.Append ("]");
 697                         return sb.ToString ();
 698                 }
 699
 700                 public ToplevelBlock ParentToplevel {
 701                         get {
 702                                 return toplevel_owner.Container;
 703                         }
 704                 }
 705
 706                 public CaptureContext ParentCaptureContext {
 707                         get {
 708                                 ToplevelBlock parent = ParentToplevel;
 709
 710                                 return (parent == null) ? null : parent.CaptureContext;
 711                         }
 712                 }
 713
 714                 // Returns the deepest of two scopes
 715                 public ScopeInfo Deepest (ScopeInfo a, ScopeInfo b)
 716                 {
 717                         ScopeInfo p;
 718
 719                         if (a == null)
 720                                 return b;
 721                         if (b == null)
 722                                 return a;
 723                         if (a == b)
 724                                 return a;
 725
 726                         //
 727                         // If they Scopes are on the same CaptureContext, we do the double
 728                         // checks just so if there is an invariant change in the future,
 729                         // we get the exception at the end
 730                         //
 731                         for (p = a; p != null; p = p.ParentScope)
 732                                 if (p == b)
 733                                         return a;
 734
 735                         for (p = b; p != null; p = p.ParentScope)
 736                                 if (p == a)
 737                                         return b;
 738
 739                         CaptureContext ca = a.CaptureContext;
 740                         CaptureContext cb = b.CaptureContext;
 741
 742                         for (CaptureContext c = ca; c != null; c = c.ParentCaptureContext)
 743                                 if (c == cb)
 744                                         return a;
 745
 746                         for (CaptureContext c = cb; c != null; c = c.ParentCaptureContext)
 747                                 if (c == ca)
 748                                         return b;
 749                         throw new Exception ("Should never be reached");
 750                 }
 751
 752                 void AdjustMethodScope (AnonymousMethod am, ScopeInfo scope)
 753                 {
 754                         am.Scope = Deepest (am.Scope, scope);
 755                 }
 756
 757                 void LinkScope (ScopeInfo scope, int id)
 758                 {
 759                         ScopeInfo parent = (ScopeInfo) scopes [id];
 760                         scope.ParentScope = parent;
 761                         parent.AddChild (scope);
 762
 763                         if (scope == topmost)
 764                                 topmost = parent;
 765                 }
 766
 767                 public void AddLocal (AnonymousMethod am, LocalInfo li)
 768                 {
 769                         if (li.Block.Toplevel != toplevel_owner){
 770                                 ParentCaptureContext.AddLocal (am, li);
 771                                 return;
 772                         }
 773                         int block_id = li.Block.ID;
 774                         ScopeInfo scope;
 775                         if (scopes [block_id] == null){
 776                                 scope = new ScopeInfo (this, li.Block);
 777                                 scopes [block_id] = scope;
 778                         } else
 779                                 scope = (ScopeInfo) scopes [block_id];
 780
 781                         if (topmost == null){
 782                                 topmost = scope;
 783                         } else {
 784                                 // Link to parent
 785                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
 786                                         if (scopes [b.ID] != null){
 787                                                 LinkScope (scope, b.ID);
 788                                                 break;
 789                                         }
 790                                 }
 791
 792                                 if (scope.ParentScope == null && ParentCaptureContext != null){
 793                                         CaptureContext pcc = ParentCaptureContext;
 794
 795                                         for (Block b = am.ContainingBlock; b != null; b = b.Parent){
 796                                                 if (pcc.scopes [b.ID] != null){
 797                                                         pcc.LinkScope (scope, b.ID);
 798                                                         break;
 799                                                 }
 800                                         }
 801                                 }
 802                         }
 803
 804                         //
 805                         // Adjust the owner
 806                         //
 807                         if (Host != null)
 808                                 AdjustMethodScope (Host, topmost);
 809
 810                         //
 811                         // Adjust the user
 812                         //
 813                         AdjustMethodScope (am, scope);
 814
 815                         if (captured_variables [li] != null)
 816                                 return;
 817
 818                         have_captured_vars = true;
 819                         captured_variables [li] = li;
 820                         scope.AddLocal (li);
 821                 }
 822
 823                 //
 824                 // Retursn the CaptureContext for the block that defines the parameter `name'
 825                 //
 826                 static CaptureContext _ContextForParameter (ToplevelBlock current, string name)
 827                 {
 828                         ToplevelBlock container = current.Container;
 829                         if (container != null){
 830                                 CaptureContext cc = _ContextForParameter (container, name);
 831                                 if (cc != null)
 832                                         return cc;
 833                         }
 834                         if (current.IsParameterReference (name))
 835                                 return current.ToplevelBlockCaptureContext;
 836                         return null;
 837                 }
 838
 839                 static CaptureContext ContextForParameter (ToplevelBlock current, string name)
 840                 {
 841                         CaptureContext cc = _ContextForParameter (current, name);
 842                         if (cc == null)
 843                                 throw new Exception (String.Format ("request for parameteter {0} failed: not found", name));
 844                         return cc;
 845                 }
 846
 847                 //
 848                 // Records the captured parameter at the appropriate CaptureContext
 849                 //
 850                 public void AddParameter (EmitContext ec, AnonymousMethod am, string name, Type t, int idx)
 851                 {
 852                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
 853
 854                         cc.AddParameterToContext (am, name, t, idx);
 855                 }
 856
 857                 //
 858                 // Records the parameters in the context
 859                 //
 860                 void AddParameterToContext (AnonymousMethod am, string name, Type t, int idx)
 861                 {
 862                         if (captured_parameters == null)
 863                                 captured_parameters = new Hashtable ();
 864                         if (captured_parameters [name] != null)
 865                                 return;
 866                         captured_parameters [name] = new CapturedParameter (t, idx);
 867
 868                         if (topmost == null){
 869                                 //
 870                                 // Create one ScopeInfo, if there are none.
 871                                 //
 872                                 topmost = new ScopeInfo (this, toplevel_owner);
 873                                 scopes [toplevel_owner.ID] = topmost;
 874                         } else {
 875                                 //
 876                                 // If the topmost ScopeInfo is not at the topblock level, insert
 877                                 // a new ScopeInfo there.
 878                                 //
 879                                 if (topmost.ScopeBlock != toplevel_owner){
 880                                         ScopeInfo par_si = new ScopeInfo (this, toplevel_owner);
 881                                         scopes [toplevel_owner.ID] = topmost;
 882                                         topmost.ParentScope = par_si;
 883                                         topmost = par_si;
 884                                 }
 885                         }
 886
 887                         topmost.HostsParameters = true;
 888                         AdjustMethodScope (am, topmost);
 889                 }
 890
 891                 //
 892                 // Captured fields are only recorded on the topmost CaptureContext, because that
 893                 // one is the one linked to the owner of instance fields
 894                 //
 895                 public void AddField (FieldExpr fe)
 896                 {
 897                         if (fe.FieldInfo.IsStatic)
 898                                 throw new Exception ("Attempt to register a static field as a captured field");
 899
 900                         CaptureContext parent = ParentCaptureContext;
 901                         if (parent != null)
 902                                 parent.AddField (fe);
 903                         else
 904                                 captured_fields [fe] = fe;
 905                 }
 906
 907
 908                 public bool HaveCapturedVariables {
 909                         get {
 910                                 return have_captured_vars;
 911                         }
 912                 }
 913
 914                 public bool HaveCapturedFields {
 915                         get {
 916                                 CaptureContext parent = ParentCaptureContext;
 917                                 if (parent != null)
 918                                         return parent.HaveCapturedFields;
 919                                 return captured_fields.Count > 0;
 920                         }
 921                 }
 922
 923                 public bool IsCaptured (LocalInfo local)
 924                 {
 925                         foreach (ScopeInfo si in scopes.Values){
 926                                 if (si.IsCaptured (local))
 927                                         return true;
 928                         }
 929                         return false;
 930                 }
 931
 932                 //
 933                 // Returns whether the parameter is captured
 934                 //
 935                 public bool IsParameterCaptured (string name)
 936                 {
 937                         if (ParentCaptureContext != null && ParentCaptureContext.IsParameterCaptured (name))
 938                                 return true;
 939
 940                         if (captured_parameters != null)
 941                                 return captured_parameters [name] != null;
 942                         return false;
 943                 }
 944
 945                 public void EmitHelperClasses (EmitContext ec)
 946                 {
 947                         if (topmost != null){
 948                                 topmost.NeedThis = HaveCapturedFields;
 949                                 topmost.EmitScopeType (ec);
 950                         }
 951                 }
 952
 953                 public void CloseHelperClasses ()
 954                 {
 955                         if (topmost != null)
 956                                 topmost.CloseTypes ();
 957                 }
 958
 959                 ScopeInfo GetScopeFromBlock (EmitContext ec, Block b)
 960                 {
 961                         ScopeInfo si;
 962
 963                         si = (ScopeInfo) scopes [b.ID];
 964                         if (si == null)
 965                                 throw new Exception ("Si is null for block " + b.ID);
 966                         si.EmitInitScope (ec);
 967
 968                         return si;
 969                 }
 970
 971                 //
 972                 // Emits the opcodes necessary to load the instance of the captured
 973                 // variable in `li'
 974                 //
 975                 public void EmitCapturedVariableInstance (EmitContext ec, LocalInfo li, AnonymousMethod am)
 976                 {
 977                         ILGenerator ig = ec.ig;
 978                         ScopeInfo si;
 979
 980                         if (li.Block.Toplevel == toplevel_owner){
 981                                 si = GetScopeFromBlock (ec, li.Block);
 982                                 ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
 983                                 return;
 984                         }
 985
 986                         si = am.Scope;
 987                         ig.Emit (OpCodes.Ldarg_0);
 988                         if (si != null){
 989                                 while (si.ScopeBlock.ID != li.Block.ID){
 990                                         if (si.ParentLink != null)
 991                                                 ig.Emit (OpCodes.Ldfld, si.ParentLink);
 992                                         si = si.ParentScope;
 993                                         if (si == null)
 994                                                 throw new Exception (
 995                                                              String.Format ("Never found block {0} starting at {1} while looking up {2}",
 996                                                                             li.Block.ID, am.Scope.ScopeBlock.ID, li.Name));
 997                                 }
 998                         }
 999                 }
1000
1001                 //
1002                 // Internal routine that loads the instance to reach parameter `name'
1003                 //
1004                 void EmitParameterInstance (EmitContext ec, string name)
1005                 {
1006                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1007                         if (cc != this){
1008                                 cc.EmitParameterInstance (ec, name);
1009                                 return;
1010                         }
1011                         Block invocation_block = ec.CurrentBlock;
1012                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1013                         ILGenerator ig = ec.ig;
1014
1015                         ScopeInfo si;
1016                         if (ec.CurrentBlock == toplevel_owner){
1017                                 si = GetScopeFromBlock (ec, toplevel_owner);
1018                                 ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
1019                                 return;
1020                         }
1021
1022                         si = ec.CurrentAnonymousMethod.Scope;
1023                         ig.Emit (OpCodes.Ldarg_0);
1024                         if (si != null){
1025                                 while (si.ParentLink != null) {
1026                                         ig.Emit (OpCodes.Ldfld, si.ParentLink);
1027                                         si = si.ParentScope;
1028                                 }
1029                         }
1030                 }
1031
1032                 //
1033                 // Emits the code necessary to load the parameter named `name' within
1034                 // an anonymous method.
1035                 //
1036                 public void EmitParameter (EmitContext ec, string name)
1037                 {
1038                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1039                         if (cc != this){
1040                                 cc.EmitParameter (ec, name);
1041                                 return;
1042                         }
1043                         EmitParameterInstance (ec, name);
1044                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1045                         ec.ig.Emit (OpCodes.Ldfld, par_info.FieldBuilder);
1046                 }
1047
1048                 //
1049                 // Implements the assignment of `source' to the paramenter named `name' within
1050                 // an anonymous method.
1051                 //
1052                 public void EmitAssignParameter (EmitContext ec, string name, Expression source, bool leave_copy, bool prepare_for_load)
1053                 {
1054                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1055                         if (cc != this){
1056                                 cc.EmitAssignParameter (ec, name, source, leave_copy, prepare_for_load);
1057                                 return;
1058                         }
1059                         ILGenerator ig = ec.ig;
1060                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1061
1062                         EmitParameterInstance (ec, name);
1063                         source.Emit (ec);
1064                         if (leave_copy)
1065                                 ig.Emit (OpCodes.Dup);
1066                         ig.Emit (OpCodes.Stfld, par_info.FieldBuilder);
1067                 }
1068
1069                 //
1070                 // Emits the address for the parameter named `name' within
1071                 // an anonymous method.
1072                 //
1073                 public void EmitAddressOfParameter (EmitContext ec, string name)
1074                 {
1075                         CaptureContext cc = ContextForParameter (ec.CurrentBlock.Toplevel, name);
1076                         if (cc != this){
1077                                 cc.EmitAddressOfParameter (ec, name);
1078                                 return;
1079                         }
1080                         EmitParameterInstance (ec, name);
1081                         CapturedParameter par_info = (CapturedParameter) captured_parameters [name];
1082                         ec.ig.Emit (OpCodes.Ldflda, par_info.FieldBuilder);
1083                 }
1084
1085                 //
1086                 // The following methods are only invoked on the host for the
1087                 // anonymous method.
1088                 //
1089                 public void EmitMethodHostInstance (EmitContext target, AnonymousMethod am)
1090                 {
1091                         ILGenerator ig = target.ig;
1092                         ScopeInfo si = am.Scope;
1093
1094                         if (si == null){
1095                                 ig.Emit (OpCodes.Ldarg_0);
1096                                 return;
1097                         }
1098
1099                         si.EmitInitScope (target);
1100                         ig.Emit (OpCodes.Ldloc, si.ScopeInstance);
1101                 }
1102
1103                 ArrayList all_scopes = new ArrayList ();
1104
1105                 public void AddScope (ScopeInfo si)
1106                 {
1107                         all_scopes.Add (si);
1108                         toplevel_owner.RegisterCaptureContext (this);
1109                 }
1110
1111                 //
1112                 // Links any scopes that were not linked previously
1113                 //
1114                 public void AdjustScopes ()
1115                 {
1116                         foreach (ScopeInfo scope in all_scopes){
1117                                 if (scope.ParentScope != null)
1118                                         continue;
1119
1120                                 for (Block b = scope.ScopeBlock.Parent; b != null; b = b.Parent){
1121                                         if (scopes [b.ID] != null){
1122                                                 LinkScope (scope, b.ID);
1123                                                 break;
1124                                         }
1125                                 }
1126
1127                                 if (scope.ParentScope == null && ParentCaptureContext != null){
1128                                         CaptureContext pcc = ParentCaptureContext;
1129
1130                                         for (Block b = Host.ContainingBlock; b != null; b = b.Parent){
1131                                                 if (pcc.scopes [b.ID] != null){
1132                                                         pcc.LinkScope (scope, b.ID);
1133                                                         break;
1134                                                 }
1135                                         }
1136                                 }
1137                         }
1138                 }
1139         }
1140 }