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