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