mcs/mcs/delegate.cs

   1 //\r
   2 // delegate.cs: Delegate Handler\r
   3 //\r
   4 // Author: Ravi Pratap (ravi@ximian.com)\r
   5 //\r
   6 // Licensed under the terms of the GNU GPL\r
   7 //\r
   8 // (C) 2001 Ximian, Inc (http://www.ximian.com)\r
   9 //\r
  10 //\r
  11 \r
  12 using System;\r
  13 using System.Collections;\r
  14 using System.Reflection;\r
  15 using System.Reflection.Emit;\r
  16 using System.Text;\r
  17 \r
  18 namespace Mono.CSharp {\r
  19 \r
  20         /// <summary>\r
  21         ///   Holds Delegates\r
  22         /// </summary>\r
  23         public class Delegate {\r
  24 \r
  25                 public readonly string Name;\r
  26                 public readonly string ReturnType;\r
  27                 public int             mod_flags;\r
  28                 public Parameters      Parameters;\r
  29                 public Attributes      OptAttributes;\r
  30                 public TypeBuilder     TypeBuilder;\r
  31 \r
  32                 public ConstructorBuilder ConstructorBuilder;\r
  33                 public MethodBuilder      InvokeBuilder;\r
  34                 public MethodBuilder      BeginInvokeBuilder;\r
  35                 public MethodBuilder      EndInvokeBuilder;\r
  36                 \r
  37                 Type [] param_types;\r
  38                 Type ret_type;\r
  39                 \r
  40                 Expression instance_expr;\r
  41                 MethodBase delegate_method;\r
  42         \r
  43                 Location loc;\r
  44 \r
  45                 const int AllowedModifiers =\r
  46                         Modifiers.NEW |\r
  47                         Modifiers.PUBLIC |\r
  48                         Modifiers.PROTECTED |\r
  49                         Modifiers.INTERNAL |\r
  50                         Modifiers.PRIVATE;\r
  51 \r
  52                 public Delegate (string type, int mod_flags, string name, Parameters param_list,\r
  53                                  Attributes attrs, Location loc)\r
  54                 {\r
  55                         this.Name       = name;\r
  56                         this.ReturnType = type;\r
  57                         this.mod_flags  = Modifiers.Check (AllowedModifiers, mod_flags, Modifiers.PUBLIC);\r
  58                         Parameters      = param_list;\r
  59                         OptAttributes   = attrs;\r
  60                         this.loc        = loc;\r
  61                 }\r
  62 \r
  63                 public void DefineDelegate (object parent_builder)\r
  64                 {\r
  65                         TypeAttributes attr;\r
  66                         \r
  67                         if (parent_builder is ModuleBuilder) {\r
  68                                 ModuleBuilder builder = (ModuleBuilder) parent_builder;\r
  69                                 attr = TypeAttributes.Public | TypeAttributes.Class | TypeAttributes.Sealed;\r
  70 \r
  71                                 TypeBuilder = builder.DefineType (Name, attr, TypeManager.delegate_type);\r
  72                         } else {\r
  73                                 TypeBuilder builder = (TypeBuilder) parent_builder;\r
  74                                 attr = TypeAttributes.NestedPublic | TypeAttributes.Class |\r
  75                                         TypeAttributes.Sealed;\r
  76 \r
  77                                 TypeBuilder = builder.DefineNestedType (\r
  78                                         Name, attr, TypeManager.delegate_type);\r
  79                         }\r
  80 \r
  81                         RootContext.TypeManager.AddDelegateType (Name, TypeBuilder, this);\r
  82                 }\r
  83 \r
  84                 public bool Populate (TypeContainer parent)\r
  85                 {\r
  86 \r
  87                         MethodAttributes mattr;\r
  88                         int i;\r
  89                         \r
  90                         // FIXME: POSSIBLY make this static, as it is always constant\r
  91                         // \r
  92                         Type [] const_arg_types = new Type [2];\r
  93                         const_arg_types [0] = TypeManager.object_type;\r
  94                         const_arg_types [1] = TypeManager.intptr_type;\r
  95 \r
  96                         mattr = MethodAttributes.RTSpecialName | MethodAttributes.SpecialName |\r
  97                                 MethodAttributes.HideBySig | MethodAttributes.Public;\r
  98 \r
  99                         ConstructorBuilder = TypeBuilder.DefineConstructor (mattr,\r
 100                                                                             CallingConventions.Standard,\r
 101                                                                             const_arg_types);\r
 102 \r
 103                         //\r
 104                         // HACK because System.Reflection.Emit is lame\r
 105                         //\r
 106                         //\r
 107                         // FIXME: POSSIBLY make these static, as they are always the same\r
 108                         Parameter [] fixed_pars = new Parameter [2];\r
 109                         fixed_pars [0] = new Parameter (null, null, Parameter.Modifier.NONE, null);\r
 110                         fixed_pars [1] = new Parameter (null, null, Parameter.Modifier.NONE, null);\r
 111                         Parameters const_parameters = new Parameters (fixed_pars, null);\r
 112                         \r
 113                         TypeManager.RegisterMethod (\r
 114                                 ConstructorBuilder,\r
 115                                 new InternalParameters (const_arg_types, const_parameters),\r
 116                                 const_arg_types);\r
 117                                 \r
 118                         \r
 119                         ConstructorBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);\r
 120                         \r
 121                         // Here the various methods like Invoke, BeginInvoke etc are defined\r
 122 \r
 123                         //\r
 124                         // TODO: Call AsAccessible for each type\r
 125                         //\r
 126 \r
 127                         //\r
 128                         // Invoke method\r
 129                         //\r
 130                         param_types = Parameters.GetParameterInfo (parent);\r
 131                         if (param_types == null)\r
 132                                 return false;\r
 133                         \r
 134                         ret_type = parent.LookupType (ReturnType, false);\r
 135                         if (ret_type == null)\r
 136                                 return false;\r
 137                         \r
 138                         CallingConventions cc = Parameters.GetCallingConvention ();\r
 139 \r
 140                         mattr = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.Virtual;\r
 141 \r
 142                         InvokeBuilder = TypeBuilder.DefineMethod ("Invoke", \r
 143                                                                   mattr,                     \r
 144                                                                   cc,\r
 145                                                                   ret_type,                  \r
 146                                                                   param_types);\r
 147 \r
 148                         for (i = 0 ; i < param_types.Length; i++) {\r
 149                                 Parameter p = Parameters.FixedParameters [i];\r
 150                                 string name = p.Name;\r
 151                                 ParameterBuilder pb = InvokeBuilder.DefineParameter (i+1, p.Attributes, name); \r
 152                         }\r
 153                         \r
 154                         InvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);\r
 155 \r
 156                         TypeManager.RegisterMethod (InvokeBuilder,\r
 157                                                     new InternalParameters (parent, Parameters),\r
 158                                                     param_types);\r
 159 \r
 160                         //\r
 161                         // BeginInvoke\r
 162                         //\r
 163                         int params_num = param_types.Length;\r
 164                         Type [] async_param_types = new Type [params_num + 2];\r
 165 \r
 166                         param_types.CopyTo (async_param_types, 0);\r
 167 \r
 168                         async_param_types [params_num] = TypeManager.asynccallback_type;\r
 169                         async_param_types [params_num + 1] = TypeManager.object_type;\r
 170 \r
 171                         mattr = MethodAttributes.Public | MethodAttributes.HideBySig | MethodAttributes.Virtual |\r
 172                                 MethodAttributes.NewSlot;\r
 173                         \r
 174                         BeginInvokeBuilder = TypeBuilder.DefineMethod ("BeginInvoke",\r
 175                                                                        mattr,\r
 176                                                                        cc,\r
 177                                                                        TypeManager.iasyncresult_type,\r
 178                                                                        async_param_types);\r
 179 \r
 180                         for (i = 0 ; i < param_types.Length; i++) {\r
 181                                 Parameter p = Parameters.FixedParameters [i];\r
 182                                 string name = p.Name;\r
 183                                 BeginInvokeBuilder.DefineParameter (i + 1, p.Attributes, name); \r
 184                         }\r
 185                         \r
 186                         BeginInvokeBuilder.DefineParameter (i + 1, ParameterAttributes.None, "callback");\r
 187                         BeginInvokeBuilder.DefineParameter (i + 2, ParameterAttributes.None, "object");\r
 188                         \r
 189                         BeginInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);\r
 190 \r
 191                         Parameter [] async_params = new Parameter [params_num + 2];\r
 192                         Parameters.FixedParameters.CopyTo (async_params, 0);\r
 193 \r
 194                         async_params [params_num] = new Parameter ("System.AsyncCallback", "callback",\r
 195                                                                    Parameter.Modifier.NONE, null);\r
 196                         async_params [params_num + 1] = new Parameter ("System.IAsyncResult", "object",\r
 197                                                                    Parameter.Modifier.NONE, null);\r
 198 \r
 199                         TypeManager.RegisterMethod (BeginInvokeBuilder,\r
 200                                                     new InternalParameters (\r
 201                                                             parent,\r
 202                                                             new Parameters (async_params, null)),\r
 203                                                     async_param_types);\r
 204 \r
 205                         //\r
 206                         // EndInvoke\r
 207                         //\r
 208                         Type [] end_param_types = new Type [1];\r
 209                         end_param_types [0] = TypeManager.iasyncresult_type;\r
 210                         \r
 211                         EndInvokeBuilder = TypeBuilder.DefineMethod ("EndInvoke",\r
 212                                                                      mattr,\r
 213                                                                      cc,\r
 214                                                                      ret_type,\r
 215                                                                      end_param_types);\r
 216                         EndInvokeBuilder.DefineParameter (1, ParameterAttributes.None, "result");\r
 217                         \r
 218                         EndInvokeBuilder.SetImplementationFlags (MethodImplAttributes.Runtime);\r
 219 \r
 220                         Parameter [] end_params = new Parameter [1];\r
 221                         end_params [0] = new Parameter ("System.IAsyncResult", "result",\r
 222                                                         Parameter.Modifier.NONE, null);\r
 223 \r
 224                         TypeManager.RegisterMethod (EndInvokeBuilder,\r
 225                                                     new InternalParameters (\r
 226                                                             parent, new Parameters (end_params, null)),\r
 227                                                     end_param_types);\r
 228 \r
 229                         return true;\r
 230                 }\r
 231 \r
 232                 /// <summary>\r
 233                 ///  Verifies whether the method in question is compatible with the delegate\r
 234                 ///  Returns the method itself if okay and null if not.\r
 235                 /// </summary>\r
 236                 public static MethodBase VerifyMethod (EmitContext ec, Type delegate_type, MethodBase mb, Location loc)\r
 237                 {\r
 238                         ParameterData pd = Invocation.GetParameterData (mb);\r
 239 \r
 240                         Expression ml = Expression.MemberLookup (ec, delegate_type, "Invoke", false, loc);\r
 241 \r
 242                         if (!(ml is MethodGroupExpr)) {\r
 243                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");\r
 244                                 return null;\r
 245                         }\r
 246 \r
 247                         MethodBase invoke_mb = ((MethodGroupExpr) ml).Methods [0];\r
 248 \r
 249                         ParameterData invoke_pd = Invocation.GetParameterData (invoke_mb);\r
 250 \r
 251                         bool mismatch = false;\r
 252                         for (int i = pd.Count; i > 0; ) {\r
 253                                 i--;\r
 254 \r
 255                                 if (invoke_pd.ParameterType (i) == pd.ParameterType (i))\r
 256                                         continue;\r
 257                                 else {\r
 258                                         mismatch = true;\r
 259                                         break;\r
 260                                 }\r
 261                         }\r
 262 \r
 263                         if (mismatch) {\r
 264                                 Report.Error (123, loc, "Method '" + Invocation.FullMethodDesc (mb) + "' does not match " +\r
 265                                               "delegate '" + FullDelegateDesc (delegate_type, invoke_mb, invoke_pd) + "'");\r
 266                                 return null;\r
 267                         }\r
 268 \r
 269                         if (((MethodInfo) invoke_mb).ReturnType == ((MethodInfo) mb).ReturnType)\r
 270                                 return mb;\r
 271                         else\r
 272                                 mismatch = true;\r
 273 \r
 274                         if (mismatch) {\r
 275                                 Report.Error (123, loc, "Method '" + Invocation.FullMethodDesc (mb) + "' does not match " +\r
 276                                               "delegate '" + FullDelegateDesc (delegate_type, invoke_mb, invoke_pd) + "'");\r
 277                                 return null;\r
 278                         }\r
 279 \r
 280                         return null;\r
 281                 }\r
 282 \r
 283                 // <summary>\r
 284                 //  Verifies whether the invocation arguments are compatible with the\r
 285                 //  delegate's target method\r
 286                 // </summary>\r
 287                 public static bool VerifyApplicability (EmitContext ec, Type delegate_type, ArrayList args, Location loc)\r
 288                 {\r
 289                         int arg_count;\r
 290 \r
 291                         if (args == null)\r
 292                                 arg_count = 0;\r
 293                         else\r
 294                                 arg_count = args.Count;\r
 295 \r
 296                         Expression ml = Expression.MemberLookup (ec, delegate_type, "Invoke", false, loc);\r
 297                         \r
 298                         if (!(ml is MethodGroupExpr)) {\r
 299                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");\r
 300                                 return false;\r
 301                         }\r
 302                         \r
 303                         MethodBase mb = ((MethodGroupExpr) ml).Methods [0];\r
 304 \r
 305                         ParameterData pd = Invocation.GetParameterData (mb);\r
 306                         \r
 307                         if (pd.Count != arg_count) {\r
 308                                 Report.Error (1593, loc,\r
 309                                               "Delegate '" + delegate_type.ToString ()\r
 310                                               + "' does not take '" + arg_count + "' arguments");\r
 311                                 return false;\r
 312                         }\r
 313 \r
 314                         for (int i = arg_count; i > 0;) {\r
 315                                 i--;\r
 316                                 Expression conv;\r
 317                                 Argument a = (Argument) args [i];\r
 318                                 Expression a_expr = a.Expr;\r
 319                                 \r
 320                                 if (pd.ParameterType (i) != a_expr.Type) {\r
 321                                         \r
 322                                         conv = Expression.ConvertImplicitStandard (ec, a_expr, pd.ParameterType (i), loc);\r
 323 \r
 324                                         if (conv == null) {\r
 325                                                 Report.Error (1594, loc,\r
 326                                                               "Delegate '" + delegate_type.ToString () +\r
 327                                                               "' has some invalid arguments.");\r
 328 \r
 329                                                 Report.Error (1503, loc,\r
 330                                                        "Argument " + (i+1) +\r
 331                                                        ": Cannot convert from '" +\r
 332                                                        TypeManager.CSharpName (a_expr.Type)\r
 333                                                        + "' to '" + TypeManager.CSharpName (pd.ParameterType (i)) + "'");\r
 334                                                 return false;\r
 335                                         }\r
 336 \r
 337                                         if (a_expr != conv)\r
 338                                                 a.Expr = conv;\r
 339                                 }\r
 340                         }\r
 341 \r
 342                         return true;\r
 343                 }\r
 344 \r
 345                 /// <summary>\r
 346                 ///  Verifies whether the delegate in question is compatible with this one in\r
 347                 ///  order to determine if instantiation from the same is possible.\r
 348                 /// </summary>\r
 349                 public static bool VerifyDelegate (EmitContext ec, Type delegate_type, Type probe_type, Location loc)\r
 350                 {\r
 351                         Expression ml = Expression.MemberLookup (ec, delegate_type, "Invoke", false, loc);\r
 352                         \r
 353                         if (!(ml is MethodGroupExpr)) {\r
 354                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");\r
 355                                 return false;\r
 356                         }\r
 357                         \r
 358                         MethodBase mb = ((MethodGroupExpr) ml).Methods [0];\r
 359                         ParameterData pd = Invocation.GetParameterData (mb);\r
 360 \r
 361                         Expression probe_ml = Expression.MemberLookup (ec, delegate_type, "Invoke", false, loc);\r
 362                         \r
 363                         if (!(probe_ml is MethodGroupExpr)) {\r
 364                                 Report.Error (-100, loc, "Internal error : could not find Invoke method!");\r
 365                                 return false;\r
 366                         }\r
 367                         \r
 368                         MethodBase probe_mb = ((MethodGroupExpr) probe_ml).Methods [0];\r
 369                         ParameterData probe_pd = Invocation.GetParameterData (probe_mb);\r
 370                         \r
 371                         if (((MethodInfo) mb).ReturnType != ((MethodInfo) probe_mb).ReturnType)\r
 372                                 return false;\r
 373 \r
 374                         if (pd.Count != probe_pd.Count)\r
 375                                 return false;\r
 376 \r
 377                         for (int i = pd.Count; i > 0; ) {\r
 378                                 i--;\r
 379 \r
 380                                 if (pd.ParameterType (i) != probe_pd.ParameterType (i) ||\r
 381                                     pd.ParameterModifier (i) != probe_pd.ParameterModifier (i))\r
 382                                         return false;\r
 383                         }\r
 384                         \r
 385                         return true;\r
 386                 }\r
 387                 \r
 388                 public static string FullDelegateDesc (Type del_type, MethodBase mb, ParameterData pd)\r
 389                 {\r
 390                         StringBuilder sb = new StringBuilder (TypeManager.CSharpName (((MethodInfo) mb).ReturnType));\r
 391                         \r
 392                         sb.Append (" " + del_type.ToString ());\r
 393                         sb.Append (" (");\r
 394 \r
 395                         int length = pd.Count;\r
 396                         \r
 397                         for (int i = length; i > 0; ) {\r
 398                                 i--;\r
 399                                 \r
 400                                 sb.Append (TypeManager.CSharpName (pd.ParameterType (length - i - 1)));\r
 401                                 if (i != 0)\r
 402                                         sb.Append (", ");\r
 403                         }\r
 404                         \r
 405                         sb.Append (")");\r
 406                         return sb.ToString ();\r
 407                         \r
 408                 }\r
 409                 \r
 410                 // Hack around System.Reflection as found everywhere else\r
 411                 public MemberInfo [] FindMembers (MemberTypes mt, BindingFlags bf, MemberFilter filter, object criteria)\r
 412                 {\r
 413                         ArrayList members = new ArrayList ();\r
 414 \r
 415                         if ((mt & MemberTypes.Method) != 0) {\r
 416                                 if (filter (ConstructorBuilder, criteria))\r
 417                                         members.Add (ConstructorBuilder);\r
 418 \r
 419                                 if (filter (InvokeBuilder, criteria))\r
 420                                         members.Add (InvokeBuilder);\r
 421 \r
 422                                 if (filter (BeginInvokeBuilder, criteria))\r
 423                                         members.Add (BeginInvokeBuilder);\r
 424 \r
 425                                 if (filter (EndInvokeBuilder, criteria))\r
 426                                         members.Add (EndInvokeBuilder);\r
 427                         }\r
 428 \r
 429                         int count = members.Count;\r
 430 \r
 431                         if (count > 0) {\r
 432                                 MemberInfo [] mi = new MemberInfo [count];\r
 433                                 members.CopyTo (mi, 0);\r
 434                                 return mi;\r
 435                         }\r
 436 \r
 437                         return null;\r
 438                 }\r
 439                 \r
 440                 public void CloseDelegate ()\r
 441                 {\r
 442                         TypeBuilder.CreateType ();\r
 443                 }\r
 444                 \r
 445                 public int ModFlags {\r
 446                         get {\r
 447                                 return mod_flags;\r
 448                         }\r
 449                 }\r
 450 \r
 451                 public Expression InstanceExpression {\r
 452                         get {\r
 453                                 return instance_expr;\r
 454                         }\r
 455                         set {\r
 456                                 instance_expr = value;\r
 457                         }\r
 458                 }\r
 459 \r
 460                 public MethodBase TargetMethod {\r
 461                         get {\r
 462                                 return delegate_method;\r
 463                         }\r
 464                         set {\r
 465                                 delegate_method = value;\r
 466                         }\r
 467                 }\r
 468 \r
 469                 public Type TargetReturnType {\r
 470                         get {\r
 471                                 return ret_type;\r
 472                         }\r
 473                 }\r
 474 \r
 475                 public Type [] ParameterTypes {\r
 476                         get {\r
 477                                 return param_types;\r
 478                         }\r
 479                 }\r
 480                 \r
 481         }\r
 482 \r
 483         public class NewDelegate : Expression {\r
 484 \r
 485                 public ArrayList Arguments;\r
 486 \r
 487                 MethodBase constructor_method;\r
 488                 MethodBase delegate_method;\r
 489                 Expression delegate_instance_expr;\r
 490 \r
 491                 Location Location;\r
 492                 \r
 493                 public NewDelegate (Type type, ArrayList Arguments, Location loc)\r
 494                 {\r
 495                         this.type = type;\r
 496                         this.Arguments = Arguments;\r
 497                         this.Location  = loc; \r
 498                 }\r
 499 \r
 500                 public override Expression DoResolve (EmitContext ec)\r
 501                 {\r
 502                         if (Arguments == null) {\r
 503                                 Report.Error (-11, Location,\r
 504                                               "Delegate creation expression takes only one argument");\r
 505                                 return null;\r
 506                         }\r
 507                         \r
 508                         if (Arguments.Count != 1) {\r
 509                                 Report.Error (-11, Location,\r
 510                                               "Delegate creation expression takes only one argument");\r
 511                                 return null;\r
 512                         }\r
 513 \r
 514                         Expression ml = Expression.MemberLookup (ec, type, ".ctor", false, Location);\r
 515 \r
 516                         if (!(ml is MethodGroupExpr)) {\r
 517                                 Report.Error (-100, Location, "Internal error : Could not find delegate constructor!");\r
 518                                 return null;\r
 519                         }\r
 520 \r
 521                         constructor_method = ((MethodGroupExpr) ml).Methods [0];\r
 522                         \r
 523                         Argument a = (Argument) Arguments [0];\r
 524                         \r
 525                         if (!a.Resolve (ec, Location))\r
 526                                 return null;\r
 527                         \r
 528                         Expression e = a.Expr;\r
 529                         \r
 530                         if (e is MethodGroupExpr) {\r
 531                                 MethodGroupExpr mg = (MethodGroupExpr) e;\r
 532                                 \r
 533                                 delegate_method  = Delegate.VerifyMethod (ec, type, mg.Methods [0], Location);\r
 534                                 \r
 535                                 if (delegate_method == null)\r
 536                                         return null;\r
 537                                 \r
 538                                 if (mg.InstanceExpression != null)\r
 539                                         delegate_instance_expr = mg.InstanceExpression.Resolve (ec);\r
 540                                 else\r
 541                                         delegate_instance_expr = null;\r
 542                                 \r
 543                                 if (delegate_instance_expr != null)\r
 544                                         if (delegate_instance_expr.Type.IsValueType)\r
 545                                                 delegate_instance_expr = new BoxedCast (delegate_instance_expr);\r
 546 \r
 547                                 DictionaryEntry de = new DictionaryEntry (delegate_method, delegate_instance_expr);\r
 548                                 TypeManager.RegisterDelegateData (type, de);\r
 549                                 \r
 550                                 eclass = ExprClass.Value;\r
 551                                 return this;\r
 552                         }\r
 553 \r
 554                         Type e_type = e.Type;\r
 555 \r
 556                         if (!TypeManager.IsDelegateType (e_type)) {\r
 557                                 Report.Error (-12, Location, "Cannot create a delegate from something " +\r
 558                                               "not a delegate or a method.");\r
 559                                 return null;\r
 560                         }\r
 561 \r
 562                         // This is what MS' compiler reports. We could always choose\r
 563                         // to be more verbose and actually give delegate-level specifics\r
 564                         \r
 565                         if (!Delegate.VerifyDelegate (ec, type, e_type, Location)) {\r
 566                                 Report.Error (29, Location, "Cannot implicitly convert type '" + e_type + "' " +\r
 567                                               "to type '" + type + "'");\r
 568                                 return null;\r
 569                         }\r
 570 \r
 571                         DictionaryEntry d = TypeManager.GetDelegateData (e_type);\r
 572 \r
 573                         delegate_instance_expr = (Expression) d.Value;\r
 574                         delegate_method        = (MethodBase) d.Key;\r
 575                         \r
 576                         eclass = ExprClass.Value;\r
 577                         return this;\r
 578                 }\r
 579                 \r
 580                 public override void Emit (EmitContext ec)\r
 581                 {\r
 582                         if (delegate_instance_expr == null)\r
 583                                 ec.ig.Emit (OpCodes.Ldnull);\r
 584                         else\r
 585                                 delegate_instance_expr.Emit (ec);\r
 586                         \r
 587                         ec.ig.Emit (OpCodes.Ldftn, (MethodInfo) delegate_method);\r
 588                         ec.ig.Emit (OpCodes.Newobj, (ConstructorInfo) constructor_method);\r
 589                 }\r
 590         }\r
 591 \r
 592         public class DelegateInvocation : ExpressionStatement {\r
 593 \r
 594                 public Expression InstanceExpr;\r
 595                 public ArrayList  Arguments;\r
 596                 public Location   Location;\r
 597 \r
 598                 MethodBase method;\r
 599                 \r
 600                 public DelegateInvocation (Expression instance_expr, ArrayList args, Location loc)\r
 601                 {\r
 602                         this.InstanceExpr = instance_expr;\r
 603                         this.Arguments = args;\r
 604                         this.Location = loc;\r
 605                 }\r
 606 \r
 607                 public override Expression DoResolve (EmitContext ec)\r
 608                 {\r
 609                         Type del_type = InstanceExpr.Type;\r
 610                         \r
 611                         if (Arguments != null){\r
 612                                 for (int i = Arguments.Count; i > 0;){\r
 613                                         --i;\r
 614                                         Argument a = (Argument) Arguments [i];\r
 615                                         \r
 616                                         if (!a.Resolve (ec, Location))\r
 617                                                 return null;\r
 618                                 }\r
 619                         }\r
 620                         \r
 621                         if (!Delegate.VerifyApplicability (ec, del_type, Arguments, Location))\r
 622                                 return null;\r
 623 \r
 624                         Expression ml = Expression.MemberLookup (ec, del_type, "Invoke", false, Location);\r
 625                         \r
 626                         if (!(ml is MethodGroupExpr)) {\r
 627                                 Report.Error (-100, Location, "Internal error : could not find Invoke method!");\r
 628                                 return null;\r
 629                         }\r
 630                         \r
 631                         method = ((MethodGroupExpr) ml).Methods [0];\r
 632                         \r
 633                         type = ((MethodInfo) method).ReturnType;\r
 634                         \r
 635                         eclass = ExprClass.Value;\r
 636                         \r
 637                         return this;\r
 638                 }\r
 639 \r
 640                 public override void Emit (EmitContext ec)\r
 641                 {\r
 642                         Delegate del = TypeManager.LookupDelegate (InstanceExpr.Type);\r
 643 \r
 644                         //\r
 645                         // Invocation on delegates call the virtual Invoke member\r
 646                         // so we are always `instance' calls\r
 647                         //\r
 648                         Invocation.EmitCall (ec, false, InstanceExpr, method, Arguments);\r
 649                 }\r
 650 \r
 651                 public override void EmitStatement (EmitContext ec)\r
 652                 {\r
 653                         Emit (ec);\r
 654                         // \r
 655                         // Pop the return value if there is one\r
 656                         //\r
 657                         if (method is MethodInfo){\r
 658                                 if (((MethodInfo) method).ReturnType != TypeManager.void_type)\r
 659                                         ec.ig.Emit (OpCodes.Pop);\r
 660                         }\r
 661                 }\r
 662 \r
 663         }\r
 664 }\r