mcs/mbas/delegate.cs

   1 //
   2 // delegate.cs: Delegate Handler
   3 //
   4 // Author: Ravi Pratap (ravi@ximian.com)
   5 //
   6 // Licensed under the terms of the GNU GPL
   7 //
   8 // (C) 2001 Ximian, Inc (http://www.ximian.com)
   9 //
  10 //
  11
  12 using System;
  13 using System.Collections;
  14 using System.Reflection;
  15 using System.Reflection.Emit;
  16 using System.Text;
  17
  18 namespace Mono.CSharp {
  19
  20         /// <summary>
  21         ///   Holds Delegates
  22         /// </summary>
  23         public class Delegate : DeclSpace {
  24                 public Expression ReturnType;
  25                 public Parameters      Parameters;
  26                 public Attributes      OptAttributes;
  27
  28                 public ConstructorBuilder ConstructorBuilder;
  29                 public MethodBuilder      InvokeBuilder;
  30                 public MethodBuilder      BeginInvokeBuilder;
  31                 public MethodBuilder      EndInvokeBuilder;
  32
  33                 Type [] param_types;
  34                 Type ret_type;
  35
  36                 Expression instance_expr;
  37                 MethodBase delegate_method;
  38
  39                 const int AllowedModifiers =
  40                         Modifiers.NEW |
  41                         Modifiers.PUBLIC |
  42                         Modifiers.PROTECTED |
  43                         Modifiers.INTERNAL |
  44                         Modifiers.UNSAFE |
  45                         Modifiers.PRIVATE;
  46
  47                 public Delegate (TypeContainer parent, Expression type, int mod_flags,
  48                                  string name, Parameters param_list,
  49                                  Attributes attrs, Location l)
  50                         : base (parent, name, l)
  51                 {
  52                         this.ReturnType = type;
  53                         ModFlags        = Modifiers.Check (AllowedModifiers, mod_flags,
  54                                                            IsTopLevel ? Modifiers.INTERNAL :
  55                                                            Modifiers.PRIVATE, l);
  56                         Parameters      = param_list;
  57                         OptAttributes   = attrs;
  58                 }
  59
  60                 public override TypeBuilder DefineType ()
  61                 {
  62                         TypeAttributes attr;
  63
  64                         if (TypeBuilder != null)
  65                                 return TypeBuilder;
  66
  67                         if (IsTopLevel) {
  68                                 ModuleBuilder builder = CodeGen.ModuleBuilder;
  69                                 attr = TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.Sealed;
  70
  71                                 TypeBuilder = builder.DefineType (
  72                                         Name, attr, TypeManager.multicast_delegate_type);
  73                         } else {
  74                                 TypeBuilder builder = Parent.TypeBuilder;
  75                                 attr = TypeAttributes.NestedPublic | TypeAttributes.Class |
  76                                         TypeAttributes.Sealed;
  77
  78                                 string name = Name.Substring (1 + Name.LastIndexOf ('.'));
  79                                 TypeBuilder = builder.DefineNestedType (
  80                                         name, attr, TypeManager.multicast_delegate_type);
  81                         }
  82
  83                         TypeManager.AddDelegateType (Name, TypeBuilder, this);
  84
  85                         return TypeBuilder;
  86                 }
  87
  88                 public override bool DefineMembers (TypeContainer container)
  89                 {
  90                         return true;
  91                 }
  92
  93                 public override bool Define (TypeContainer container)
  94                 {
  95                         MethodAttributes mattr;
  96                         int i;
  97
  98                         // FIXME: POSSIBLY make this static, as it is always constant
  99                         //
 100                         Type [] const_arg_types = new Type [2];
 101                         const_arg_types [0] = TypeManager.object_type;
 102                         const_arg_types [1] = TypeManager.intptr_type;
 103
 104                         mattr = MethodAttributes.RTSpecialName | MethodAttributes.SpecialName |
 105                                 MethodAttributes.HideBySig | MethodAttributes.Public;
 106
 107                         ConstructorBuilder = TypeBuilder.DefineConstructor (mattr,
 108                                                                             CallingConventions.Standard,
 109                                                                             const_arg_types);
 110
 111                         ConstructorBuilder.DefineParameter (1, ParameterAttributes.None, "object");
 112                         ConstructorBuilder.DefineParameter (2, ParameterAttributes.None, "method");
 113                         //
 114                         // HACK because System.Reflection.Emit is lame
 115                         //
 116                         //
 117                         // FIXME: POSSIBLY make these static, as they are always the same
 118                         Parameter [] fixed_pars = new Parameter [2];
 119                         fixed_pars [0] = new Parameter (null, null, Parameter.Modifier.NONE, null);
 120                         fixed_pars [1] = new Parameter (null, null, Parameter.Modifier.NONE, null);
 121                         Parameters const_parameters = new Parameters (fixed_pars, null, Location);
 122
 123                         TypeManager.RegisterMethod (
 124                                 ConstructorBuilder,
 125                                 new InternalParameters (const_arg_types, const_parameters),
 126                                 const_arg_types);
 127
 128
 129                         ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 130
 131                         //
 132                         // Here the various methods like Invoke, BeginInvoke etc are defined
 133                         //
 134                         // First, call the `out of band' special method for
 135                         // defining recursively any types we need:
 136
 137                         if (!Parameters.ComputeAndDefineParameterTypes (this))
 138                                 return false;
 139
 140                         param_types = Parameters.GetParameterInfo (this);
 141                         if (param_types == null)
 142                                 return false;
 143
 144                         //
 145                         // Invoke method
 146                         //
 147
 148                         // Check accessibility
 149                         foreach (Type partype in param_types)
 150                                 if (!container.AsAccessible (partype, ModFlags)) {
 151                                         Report.Error (59, Location,
 152                                                       "Inconsistent accessibility: parameter type `" +
 153                                                       TypeManager.CSharpName (partype) + "` is less " +
 154                                                       "accessible than delegate `" + Name + "'");
 155                                         return false;
 156                                 }
 157
 158                         ReturnType = ResolveTypeExpr (ReturnType, false, Location);
 159                         ret_type = ReturnType.Type;
 160                         if (ret_type == null)
 161                                 return false;
 162
 163                         if (!container.AsAccessible (ret_type, ModFlags)) {
 164                                 Report.Error (58, Location,
 165                                               "Inconsistent accessibility: return type `" +
 166                                               TypeManager.CSharpName (ret_type) + "` is less " +
 167                                               "accessible than delegate `" + Name + "'");
 168                                 return false;
 169                         }
 170
 171                         //
 172                         // We don't have to check any others because they are all
 173                         // guaranteed to be accessible - they are standard types.
 174                         //
 175
 176                         CallingConventions cc = Parameters.GetCallingConvention ();
 177
 178                         mattr = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.Virtual;
 179
 180                         InvokeBuilder = TypeBuilder.DefineMethod ("Invoke",
 181                                                                   mattr,
 182                                                                   cc,
 183                                                                   ret_type,
 184                                                                   param_types);
 185
 186                         i = 0;
 187                         if (Parameters.FixedParameters != null){
 188                                 int top = Parameters.FixedParameters.Length;
 189                                 Parameter p;
 190
 191                                 for (; i < top; i++) {
 192                                         p = Parameters.FixedParameters [i];
 193
 194                                         InvokeBuilder.DefineParameter (
 195                                                 i+1, p.Attributes, p.Name);
 196                                 }
 197                         }
 198                         if (Parameters.ArrayParameter != null){
 199                                 Parameter p = Parameters.ArrayParameter;
 200
 201                                 InvokeBuilder.DefineParameter (
 202                                         i+1, p.Attributes, p.Name);
 203                         }
 204
 205                         InvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 206
 207                         TypeManager.RegisterMethod (InvokeBuilder,
 208                                                     new InternalParameters (container, Parameters),
 209                                                     param_types);
 210
 211                         //
 212                         // BeginInvoke
 213                         //
 214                         int params_num = param_types.Length;
 215                         Type [] async_param_types = new Type [params_num + 2];
 216
 217                         param_types.CopyTo (async_param_types, 0);
 218
 219                         async_param_types [params_num] = TypeManager.asynccallback_type;
 220                         async_param_types [params_num + 1] = TypeManager.object_type;
 221
 222                         mattr = MethodAttributes.Public | MethodAttributes.HideBySig |
 223                                 MethodAttributes.Virtual | MethodAttributes.NewSlot;
 224
 225                         BeginInvokeBuilder = TypeBuilder.DefineMethod ("BeginInvoke",
 226                                                                        mattr,
 227                                                                        cc,
 228                                                                        TypeManager.iasyncresult_type,
 229                                                                        async_param_types);
 230
 231                         i = 0;
 232                         if (Parameters.FixedParameters != null){
 233                                 int top = Parameters.FixedParameters.Length;
 234                                 Parameter p;
 235
 236                                 for (i = 0 ; i < top; i++) {
 237                                         p = Parameters.FixedParameters [i];
 238
 239                                         BeginInvokeBuilder.DefineParameter (
 240                                                 i+1, p.Attributes, p.Name);
 241                                 }
 242                         }
 243                         if (Parameters.ArrayParameter != null){
 244                                 Parameter p = Parameters.ArrayParameter;
 245
 246                                 BeginInvokeBuilder.DefineParameter (
 247                                         i+1, p.Attributes, p.Name);
 248                                 i++;
 249                         }
 250
 251                         BeginInvokeBuilder.DefineParameter (i + 1, ParameterAttributes.None, "callback");
 252                         BeginInvokeBuilder.DefineParameter (i + 2, ParameterAttributes.None, "object");
 253
 254                         BeginInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 255
 256                         Parameter [] async_params = new Parameter [params_num + 2];
 257                         int n = 0;
 258                         if (Parameters.FixedParameters != null){
 259                                 Parameters.FixedParameters.CopyTo (async_params, 0);
 260                                 n = Parameters.FixedParameters.Length;
 261                         }
 262                         if (Parameters.ArrayParameter != null)
 263                                 async_params [n] = Parameters.ArrayParameter;
 264
 265                         async_params [params_num] = new Parameter (
 266                                 TypeManager.system_asynccallback_expr, "callback",
 267                                                                    Parameter.Modifier.NONE, null);
 268                         async_params [params_num + 1] = new Parameter (
 269                                 TypeManager.system_object_expr, "object",
 270                                                                    Parameter.Modifier.NONE, null);
 271
 272                         Parameters async_parameters = new Parameters (async_params, null, Location);
 273
 274                         async_parameters.ComputeAndDefineParameterTypes (this);
 275                         TypeManager.RegisterMethod (BeginInvokeBuilder,
 276                                                     new InternalParameters (container, async_parameters),
 277                                                     async_param_types);
 278
 279                         //
 280                         // EndInvoke
 281                         //
 282                         Type [] end_param_types = new Type [1];
 283                         end_param_types [0] = TypeManager.iasyncresult_type;
 284
 285                         EndInvokeBuilder = TypeBuilder.DefineMethod ("EndInvoke",
 286                                                                      mattr,
 287                                                                      cc,
 288                                                                      ret_type,
 289                                                                      end_param_types);
 290                         EndInvokeBuilder.DefineParameter (1, ParameterAttributes.None, "result");
 291
 292                         EndInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);
 293
 294                         Parameter [] end_params = new Parameter [1];
 295                         end_params [0] = new Parameter (
 296                                 TypeManager.system_iasyncresult_expr, "result",
 297                                                         Parameter.Modifier.NONE, null);
 298
 299                         TypeManager.RegisterMethod (
 300                                 EndInvokeBuilder, new InternalParameters (
 301                                         container,
 302                                         new Parameters (
 303                                                 end_params, null, Location)),
 304                                                     end_param_types);
 305
 306                         return true;
 307                 }
 308
 309                 /// <summary>
 310                 ///  Verifies whether the method in question is compatible with the delegate
 311                 ///  Returns the method itself if okay and null if not.
 312                 /// </summary>
 313                 public static MethodBase VerifyMethod (EmitContext ec, Type delegate_type, MethodBase mb,
 314                                                        Location loc)
 315                 {
 316                         ParameterData pd = Invocation.GetParameterData (mb);
 317
 318                         int pd_count = pd.Count;
 319
 320                         Expression ml = Expression.MemberLookup (
 321                                 ec, delegate_type, "Invoke", loc);
 322
 323                         if (!(ml is MethodGroupExpr)) {
 324                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");
 325                                 return null;
 326                         }
 327
 328                         MethodBase invoke_mb = ((MethodGroupExpr) ml).Methods [0];
 329
 330                         ParameterData invoke_pd = Invocation.GetParameterData (invoke_mb);
 331
 332                         if (invoke_pd.Count != pd_count)
 333                                 return null;
 334
 335                         for (int i = pd_count; i > 0; ) {
 336                                 i--;
 337
 338                                 if (invoke_pd.ParameterType (i) == pd.ParameterType (i))
 339                                         continue;
 340                                 else
 341                                         return null;
 342                         }
 343
 344                         if (((MethodInfo) invoke_mb).ReturnType == ((MethodInfo) mb).ReturnType)
 345                                 return mb;
 346                         else
 347                                 return null;
 348                 }
 349
 350                 // <summary>
 351                 //  Verifies whether the invocation arguments are compatible with the
 352                 //  delegate's target method
 353                 // </summary>
 354                 public static bool VerifyApplicability (EmitContext ec,
 355                                                         Type delegate_type,
 356                                                         ArrayList args,
 357                                                         Location loc)
 358                 {
 359                         int arg_count;
 360
 361                         if (args == null)
 362                                 arg_count = 0;
 363                         else
 364                                 arg_count = args.Count;
 365
 366                         Expression ml = Expression.MemberLookup (
 367                                 ec, delegate_type, "Invoke", loc);
 368
 369                         if (!(ml is MethodGroupExpr)) {
 370                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");
 371                                 return false;
 372                         }
 373
 374                         MethodBase mb = ((MethodGroupExpr) ml).Methods [0];
 375                         ParameterData pd = Invocation.GetParameterData (mb);
 376
 377                         int pd_count = pd.Count;
 378
 379                         bool not_params_method = (pd.ParameterModifier (pd_count - 1) != Parameter.Modifier.PARAMS);
 380
 381                         if (not_params_method && pd_count != arg_count) {
 382                                 Report.Error (1593, loc,
 383                                               "Delegate '" + delegate_type.ToString ()
 384                                               + "' does not take '" + arg_count + "' arguments");
 385                                 return false;
 386                         }
 387
 388                         return Invocation.VerifyArgumentsCompat (ec, args, arg_count, mb, !not_params_method,
 389                                                                  delegate_type, loc);
 390                 }
 391
 392                 /// <summary>
 393                 ///  Verifies whether the delegate in question is compatible with this one in
 394                 ///  order to determine if instantiation from the same is possible.
 395                 /// </summary>
 396                 public static bool VerifyDelegate (EmitContext ec, Type delegate_type, Type probe_type, Location loc)
 397                 {
 398                         Expression ml = Expression.MemberLookup (
 399                                 ec, delegate_type, "Invoke", loc);
 400
 401                         if (!(ml is MethodGroupExpr)) {
 402                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");
 403                                 return false;
 404                         }
 405
 406                         MethodBase mb = ((MethodGroupExpr) ml).Methods [0];
 407                         ParameterData pd = Invocation.GetParameterData (mb);
 408
 409                         Expression probe_ml = Expression.MemberLookup (
 410                                 ec, delegate_type, "Invoke", loc);
 411
 412                         if (!(probe_ml is MethodGroupExpr)) {
 413                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");
 414                                 return false;
 415                         }
 416
 417                         MethodBase probe_mb = ((MethodGroupExpr) probe_ml).Methods [0];
 418                         ParameterData probe_pd = Invocation.GetParameterData (probe_mb);
 419
 420                         if (((MethodInfo) mb).ReturnType != ((MethodInfo) probe_mb).ReturnType)
 421                                 return false;
 422
 423                         if (pd.Count != probe_pd.Count)
 424                                 return false;
 425
 426                         for (int i = pd.Count; i > 0; ) {
 427                                 i--;
 428
 429                                 if (pd.ParameterType (i) != probe_pd.ParameterType (i) ||
 430                                     pd.ParameterModifier (i) != probe_pd.ParameterModifier (i))
 431                                         return false;
 432                         }
 433
 434                         return true;
 435                 }
 436
 437                 public static string FullDelegateDesc (Type del_type, MethodBase mb, ParameterData pd)
 438                 {
 439                         StringBuilder sb = new StringBuilder (TypeManager.CSharpName (((MethodInfo) mb).ReturnType));
 440
 441                         sb.Append (" " + del_type.ToString ());
 442                         sb.Append (" (");
 443
 444                         int length = pd.Count;
 445
 446                         for (int i = length; i > 0; ) {
 447                                 i--;
 448
 449                                 sb.Append (TypeManager.CSharpName (pd.ParameterType (length - i - 1)));
 450                                 if (i != 0)
 451                                         sb.Append (", ");
 452                         }
 453
 454                         sb.Append (")");
 455                         return sb.ToString ();
 456
 457                 }
 458
 459                 // Hack around System.Reflection as found everywhere else
 460                 public override MemberList FindMembers (MemberTypes mt, BindingFlags bf,
 461                                                         MemberFilter filter, object criteria)
 462                 {
 463                         ArrayList members = new ArrayList ();
 464
 465                         if ((mt & MemberTypes.Method) != 0) {
 466                                 if (ConstructorBuilder != null)
 467                                 if (filter (ConstructorBuilder, criteria))
 468                                         members.Add (ConstructorBuilder);
 469
 470                                 if (InvokeBuilder != null)
 471                                 if (filter (InvokeBuilder, criteria))
 472                                         members.Add (InvokeBuilder);
 473
 474                                 if (BeginInvokeBuilder != null)
 475                                 if (filter (BeginInvokeBuilder, criteria))
 476                                         members.Add (BeginInvokeBuilder);
 477
 478                                 if (EndInvokeBuilder != null)
 479                                 if (filter (EndInvokeBuilder, criteria))
 480                                         members.Add (EndInvokeBuilder);
 481                         }
 482
 483                         return new MemberList (members);
 484                 }
 485
 486                 public override MemberCache MemberCache {
 487                         get {
 488                                 return null;
 489                         }
 490                 }
 491
 492                 public void CloseDelegate ()
 493                 {
 494                         TypeBuilder.CreateType ();
 495                 }
 496
 497                 public Expression InstanceExpression {
 498                         get {
 499                                 return instance_expr;
 500                         }
 501                         set {
 502                                 instance_expr = value;
 503                         }
 504                 }
 505
 506                 public MethodBase TargetMethod {
 507                         get {
 508                                 return delegate_method;
 509                         }
 510                         set {
 511                                 delegate_method = value;
 512                         }
 513                 }
 514
 515                 public Type TargetReturnType {
 516                         get {
 517                                 return ret_type;
 518                         }
 519                 }
 520
 521                 public Type [] ParameterTypes {
 522                         get {
 523                                 return param_types;
 524                         }
 525                 }
 526
 527         }
 528
 529         public class NewDelegate : Expression {
 530
 531                 public ArrayList Arguments;
 532
 533                 MethodBase constructor_method;
 534                 MethodBase delegate_method;
 535                 Expression delegate_instance_expr;
 536
 537                 public NewDelegate (Type type, ArrayList Arguments, Location loc)
 538                 {
 539                         this.type = type;
 540                         this.Arguments = Arguments;
 541                         this.loc  = loc;
 542                 }
 543
 544                 public override Expression DoResolve (EmitContext ec)
 545                 {
 546                         if (Arguments == null) {
 547                                 Report.Error (-11, loc,
 548                                               "Delegate creation expression takes only one argument");
 549                                 return null;
 550                         }
 551
 552                         if (Arguments.Count != 1) {
 553                                 Report.Error (-11, loc,
 554                                               "Delegate creation expression takes only one argument");
 555                                 return null;
 556                         }
 557
 558                         Expression ml = Expression.MemberLookup (
 559                                 ec, type, ".ctor", loc);
 560
 561                         if (!(ml is MethodGroupExpr)) {
 562                                 Report.Error (-100, loc, "Internal error : Could not find delegate constructor!");
 563                                 return null;
 564                         }
 565
 566                         constructor_method = ((MethodGroupExpr) ml).Methods [0];
 567                         Argument a = (Argument) Arguments [0];
 568
 569                         if (!a.ResolveMethodGroup (ec, Location))
 570                                 return null;
 571
 572                         Expression e = a.Expr;
 573
 574                         Expression invoke_method = Expression.MemberLookup (
 575                                 ec, type, "Invoke", MemberTypes.Method,
 576                                 Expression.AllBindingFlags, loc);
 577
 578                         if (invoke_method == null) {
 579                                 Report.Error (-200, loc, "Internal error ! COuld not find Invoke method!");
 580                                 return null;
 581                         }
 582
 583                         if (e is MethodGroupExpr) {
 584                                 MethodGroupExpr mg = (MethodGroupExpr) e;
 585
 586                                 foreach (MethodInfo mi in mg.Methods){
 587                                         delegate_method  = Delegate.VerifyMethod (ec, type, mi, loc);
 588
 589                                         if (delegate_method != null)
 590                                                 break;
 591                                 }
 592
 593                                 if (delegate_method == null) {
 594                                         string method_desc;
 595                                         if (mg.Methods.Length > 1)
 596                                                 method_desc = mg.Methods [0].Name;
 597                                         else
 598                                                 method_desc = Invocation.FullMethodDesc (mg.Methods [0]);
 599
 600                                         MethodBase dm = ((MethodGroupExpr) invoke_method).Methods [0];
 601                                         ParameterData param = Invocation.GetParameterData (dm);
 602                                         string delegate_desc = Delegate.FullDelegateDesc (type, dm, param);
 603
 604                                         Report.Error (123, loc, "Method '" + method_desc + "' does not " +
 605                                                       "match delegate '" + delegate_desc + "'");
 606
 607                                         return null;
 608                                 }
 609
 610                                 if (mg.InstanceExpression != null)
 611                                         delegate_instance_expr = mg.InstanceExpression.Resolve (ec);
 612                                 else {
 613                                         if (!ec.IsStatic)
 614                                                 delegate_instance_expr = ec.This;
 615                                         else
 616                                                 delegate_instance_expr = null;
 617                                 }
 618
 619                                 if (delegate_instance_expr != null)
 620                                         if (delegate_instance_expr.Type.IsValueType)
 621                                                 delegate_instance_expr = new BoxedCast (delegate_instance_expr);
 622
 623                                 eclass = ExprClass.Value;
 624                                 return this;
 625                         }
 626
 627                         Type e_type = e.Type;
 628
 629                         if (!TypeManager.IsDelegateType (e_type)) {
 630                                 Report.Error (-12, loc, "Cannot create a delegate from something " +
 631                                               "not a delegate or a method.");
 632                                 return null;
 633                         }
 634
 635                         // This is what MS' compiler reports. We could always choose
 636                         // to be more verbose and actually give delegate-level specifics
 637
 638                         if (!Delegate.VerifyDelegate (ec, type, e_type, loc)) {
 639                                 Report.Error (29, loc, "Cannot implicitly convert type '" + e_type + "' " +
 640                                               "to type '" + type + "'");
 641                                 return null;
 642                         }
 643
 644                         delegate_instance_expr = e;
 645                         delegate_method        = ((MethodGroupExpr) invoke_method).Methods [0];
 646
 647                         eclass = ExprClass.Value;
 648                         return this;
 649                 }
 650
 651                 public override void Emit (EmitContext ec)
 652                 {
 653                         if (delegate_instance_expr == null ||
 654                             delegate_method.IsStatic)
 655                                 ec.ig.Emit (OpCodes.Ldnull);
 656                         else
 657                                 delegate_instance_expr.Emit (ec);
 658
 659                         ec.ig.Emit (OpCodes.Ldftn, (MethodInfo) delegate_method);
 660                         ec.ig.Emit (OpCodes.Newobj, (ConstructorInfo) constructor_method);
 661                 }
 662         }
 663
 664         public class DelegateInvocation : ExpressionStatement {
 665
 666                 public Expression InstanceExpr;
 667                 public ArrayList  Arguments;
 668
 669                 MethodBase method;
 670
 671                 public DelegateInvocation (Expression instance_expr, ArrayList args, Location loc)
 672                 {
 673                         this.InstanceExpr = instance_expr;
 674                         this.Arguments = args;
 675                         this.loc = loc;
 676                 }
 677
 678                 public override Expression DoResolve (EmitContext ec)
 679                 {
 680                         if (InstanceExpr is EventExpr) {
 681
 682                                 EventInfo ei = ((EventExpr) InstanceExpr).EventInfo;
 683
 684                                 Expression ml = MemberLookup (
 685                                         ec, ec.ContainerType, ei.Name,
 686                                         MemberTypes.Event, AllBindingFlags | BindingFlags.DeclaredOnly, loc);
 687
 688                                 if (ml == null) {
 689                                         //
 690                                         // If this is the case, then the Event does not belong
 691                                         // to this Type and so, according to the spec
 692                                         // cannot be accessed directly
 693                                         //
 694                                         // Note that target will not appear as an EventExpr
 695                                         // in the case it is being referenced within the same type container;
 696                                         // it will appear as a FieldExpr in that case.
 697                                         //
 698
 699                                         Assign.error70 (ei, loc);
 700                                         return null;
 701                                 }
 702                         }
 703
 704
 705                         Type del_type = InstanceExpr.Type;
 706                         if (del_type == null)
 707                                 return null;
 708
 709                         if (Arguments != null){
 710                                 foreach (Argument a in Arguments){
 711                                         if (!a.Resolve (ec, loc))
 712                                                 return null;
 713                                 }
 714                         }
 715
 716                         if (!Delegate.VerifyApplicability (ec, del_type, Arguments, loc))
 717                                 return null;
 718
 719                         Expression lookup = Expression.MemberLookup (ec, del_type, "Invoke", loc);
 720                         if (!(lookup is MethodGroupExpr)) {
 721                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");
 722                                 return null;
 723                         }
 724
 725                         method = ((MethodGroupExpr) lookup).Methods [0];
 726                         type = ((MethodInfo) method).ReturnType;
 727                         eclass = ExprClass.Value;
 728
 729                         return this;
 730                 }
 731
 732                 public override void Emit (EmitContext ec)
 733                 {
 734                         Delegate del = TypeManager.LookupDelegate (InstanceExpr.Type);
 735
 736                         //
 737                         // Invocation on delegates call the virtual Invoke member
 738                         // so we are always `instance' calls
 739                         //
 740                         Invocation.EmitCall (ec, false, false, InstanceExpr, method, Arguments, loc);
 741                 }
 742
 743                 public override void EmitStatement (EmitContext ec)
 744                 {
 745                         Emit (ec);
 746                         //
 747                         // Pop the return value if there is one
 748                         //
 749                         if (method is MethodInfo){
 750                                 if (((MethodInfo) method).ReturnType != TypeManager.void_type)
 751                                         ec.ig.Emit (OpCodes.Pop);
 752                         }
 753                 }
 754
 755         }
 756 }