mcs/mcs/pending.cs

   1 //
   2 // pending.cs: Pending method implementation
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@gnu.org)
   6 //
   7 // Licensed under the terms of the GNU GPL
   8 //
   9 // (C) 2001, 2002 Ximian, Inc (http://www.ximian.com)
  10 //
  11 //
  12
  13 using System;
  14 using System.Collections;
  15 using System.Reflection;
  16 using System.Reflection.Emit;
  17
  18 namespace Mono.CSharp {
  19
  20         struct TypeAndMethods {
  21                 public Type          type;
  22                 public MethodInfo [] methods;
  23
  24                 //
  25                 // Whether it is optional, this is used to allow the explicit/implicit
  26                 // implementation when a parent class already implements an interface.
  27                 //
  28                 // For example:
  29                 //
  30                 // class X : IA { }  class Y : X, IA { IA.Explicit (); }
  31                 //
  32                 public bool          optional;
  33
  34                 // Far from ideal, but we want to avoid creating a copy
  35                 // of methods above.
  36                 public Type [][]     args;
  37
  38                 //
  39                 // This flag on the method says `We found a match, but
  40                 // because it was private, we could not use the match
  41                 //
  42                 public bool []       found;
  43
  44                 // If a method is defined here, then we always need to
  45                 // create a proxy for it.  This is used when implementing
  46                 // an interface's indexer with a different IndexerName.
  47                 public MethodInfo [] need_proxy;
  48         }
  49
  50         public class PendingImplementation {
  51                 /// <summary>
  52                 ///   The container for this PendingImplementation
  53                 /// </summary>
  54                 TypeContainer container;
  55
  56                 /// <summary>
  57                 ///   This filter is used by FindMembers, and it is used to
  58                 ///   extract only virtual/abstract fields
  59                 /// </summary>
  60                 static MemberFilter virtual_method_filter;
  61
  62                 /// <summary>
  63                 ///   This is the array of TypeAndMethods that describes the pending implementations
  64                 ///   (both interfaces and abstract methods in parent class)
  65                 /// </summary>
  66                 TypeAndMethods [] pending_implementations;
  67
  68                 static bool IsVirtualFilter (MemberInfo m, object filterCriteria)
  69                 {
  70                         if (!(m is MethodInfo))
  71                                 return false;
  72
  73                         return ((MethodInfo) m).IsVirtual;
  74                 }
  75
  76                 /// <summary>
  77                 ///   Inits the virtual_method_filter
  78                 /// </summary>
  79                 static PendingImplementation ()
  80                 {
  81                         virtual_method_filter = new MemberFilter (IsVirtualFilter);
  82                 }
  83
  84                 // <remarks>
  85                 //   Returns a list of the abstract methods that are exposed by all of our
  86                 //   parents that we must implement.  Notice that this `flattens' the
  87                 //   method search space, and takes into account overrides.
  88                 // </remarks>
  89                 static ArrayList GetAbstractMethods (Type t)
  90                 {
  91                         ArrayList list = null;
  92                         bool searching = true;
  93                         Type current_type = t;
  94
  95                         do {
  96                                 MemberList mi;
  97
  98                                 mi = TypeContainer.FindMembers (
  99                                         current_type, MemberTypes.Method,
 100                                         BindingFlags.Public | BindingFlags.Instance |
 101                                         BindingFlags.DeclaredOnly,
 102                                         virtual_method_filter, null);
 103
 104                                 if (current_type == TypeManager.object_type)
 105                                         searching = false;
 106                                 else {
 107                                         current_type = current_type.BaseType;
 108                                         if (!current_type.IsAbstract)
 109                                                 searching = false;
 110                                 }
 111
 112                                 if (mi.Count == 0)
 113                                         continue;
 114
 115                                 if (mi.Count == 1 && !(mi [0] is MethodBase))
 116                                         searching = false;
 117                                 else
 118                                         list = TypeManager.CopyNewMethods (list, mi);
 119                         } while (searching);
 120
 121                         if (list == null)
 122                                 return null;
 123
 124                         for (int i = 0; i < list.Count; i++){
 125                                 while (list.Count > i && !((MethodInfo) list [i]).IsAbstract)
 126                                         list.RemoveAt (i);
 127                         }
 128
 129                         if (list.Count == 0)
 130                                 return null;
 131
 132                         return list;
 133                 }
 134
 135                 PendingImplementation (TypeContainer container, MissingInterfacesInfo [] missing_ifaces, ArrayList abstract_methods, int total)
 136                 {
 137                         TypeBuilder type_builder = container.TypeBuilder;
 138
 139                         this.container = container;
 140                         pending_implementations = new TypeAndMethods [total];
 141
 142                         int i = 0;
 143                         foreach (MissingInterfacesInfo missing in missing_ifaces){
 144                                 MethodInfo [] mi;
 145                                 Type t = missing.Type;
 146
 147                                 if (t is TypeBuilder){
 148                                         Interface iface;
 149
 150                                         iface = TypeManager.LookupInterface (t);
 151
 152                                         mi = iface.GetMethods (container);
 153                                 } else
 154                                         mi = t.GetMethods ();
 155
 156                                 int count = mi.Length;
 157                                 pending_implementations [i].type = missing.Type;
 158                                 pending_implementations [i].optional = missing.Optional;
 159                                 pending_implementations [i].methods = mi;
 160                                 pending_implementations [i].args = new Type [count][];
 161                                 pending_implementations [i].found = new bool [count];
 162                                 pending_implementations [i].need_proxy = new MethodInfo [count];
 163
 164                                 int j = 0;
 165                                 foreach (MethodInfo m in mi){
 166                                         Type [] types = TypeManager.GetArgumentTypes (m);
 167
 168                                         pending_implementations [i].args [j] = types;
 169                                         j++;
 170                                 }
 171                                 i++;
 172                         }
 173
 174                         if (abstract_methods != null){
 175                                 int count = abstract_methods.Count;
 176                                 pending_implementations [i].methods = new MethodInfo [count];
 177                                 pending_implementations [i].need_proxy = new MethodInfo [count];
 178
 179                                 abstract_methods.CopyTo (pending_implementations [i].methods, 0);
 180                                 pending_implementations [i].found = new bool [count];
 181                                 pending_implementations [i].args = new Type [count][];
 182                                 pending_implementations [i].type = type_builder;
 183
 184                                 int j = 0;
 185                                 foreach (MemberInfo m in abstract_methods){
 186                                         MethodInfo mi = (MethodInfo) m;
 187
 188                                         Type [] types = TypeManager.GetArgumentTypes (mi);
 189
 190                                         pending_implementations [i].args [j] = types;
 191                                         j++;
 192                                 }
 193                         }
 194                 }
 195
 196                 struct MissingInterfacesInfo {
 197                         public Type Type;
 198                         public bool Optional;
 199
 200                         public MissingInterfacesInfo (Type t)
 201                         {
 202                                 Type = t;
 203                                 Optional = false;
 204                         }
 205                 }
 206
 207                 static MissingInterfacesInfo [] EmptyMissingInterfacesInfo = new MissingInterfacesInfo [0];
 208
 209                 static MissingInterfacesInfo [] GetMissingInterfaces (TypeBuilder type_builder)
 210                 {
 211                         //
 212                         // Notice that TypeBuilders will only return the interfaces that the Type
 213                         // is supposed to implement, not all the interfaces that the type implements.
 214                         //
 215                         // Even better -- on MS it returns an empty array, no matter what.
 216                         //
 217                         // Completely broken.  So we do it ourselves!
 218                         //
 219                         TypeExpr [] impl = TypeManager.GetExplicitInterfaces (type_builder);
 220
 221                         if (impl == null || impl.Length == 0)
 222                                 return EmptyMissingInterfacesInfo;
 223
 224                         MissingInterfacesInfo [] ret = new MissingInterfacesInfo [impl.Length];
 225
 226                         for (int i = 0; i < impl.Length; i++)
 227                                 ret [i] = new MissingInterfacesInfo (impl [i].Type);
 228
 229                         // we really should not get here because Object doesnt implement any
 230                         // interfaces. But it could implement something internal, so we have
 231                         // to handle that case.
 232                         if (type_builder.BaseType == null)
 233                                 return ret;
 234
 235                         TypeExpr [] parent_impls = TypeManager.GetInterfaces (type_builder.BaseType);
 236
 237                         foreach (TypeExpr te in parent_impls) {
 238                                 Type t = te.Type;
 239
 240                                 for (int i = 0; i < ret.Length; i ++) {
 241                                         if (t == ret [i].Type) {
 242                                                 ret [i].Optional = true;
 243                                                 break;
 244                                         }
 245                                 }
 246                         }
 247                         return ret;
 248                 }
 249
 250                 //
 251                 // Factory method: if there are pending implementation methods, we return a PendingImplementation
 252                 // object, otherwise we return null.
 253                 //
 254                 // Register method implementations are either abstract methods
 255                 // flagged as such on the base class or interface methods
 256                 //
 257                 static public PendingImplementation GetPendingImplementations (TypeContainer container)
 258                 {
 259                         TypeBuilder type_builder = container.TypeBuilder;
 260                         MissingInterfacesInfo [] missing_interfaces;
 261                         Type b = type_builder.BaseType;
 262
 263                         missing_interfaces = GetMissingInterfaces (type_builder);
 264
 265                         //
 266                         // If we are implementing an abstract class, and we are not
 267                         // ourselves abstract, and there are abstract methods (C# allows
 268                         // abstract classes that have no abstract methods), then allocate
 269                         // one slot.
 270                         //
 271                         // We also pre-compute the methods.
 272                         //
 273                         bool implementing_abstract = ((b != null) && b.IsAbstract && !type_builder.IsAbstract);
 274                         ArrayList abstract_methods = null;
 275
 276                         if (implementing_abstract){
 277                                 abstract_methods = GetAbstractMethods (b);
 278
 279                                 if (abstract_methods == null)
 280                                         implementing_abstract = false;
 281                         }
 282
 283                         int total = missing_interfaces.Length +  (implementing_abstract ? 1 : 0);
 284                         if (total == 0)
 285                                 return null;
 286
 287                         return new PendingImplementation (container, missing_interfaces, abstract_methods, total);
 288                 }
 289
 290                 public enum Operation {
 291                         //
 292                         // If you change this, review the whole InterfaceMethod routine as there
 293                         // are a couple of assumptions on these three states
 294                         //
 295                         Lookup, ClearOne, ClearAll
 296                 }
 297
 298                 /// <summary>
 299                 ///   Whether the specified method is an interface method implementation
 300                 /// </summary>
 301                 public MethodInfo IsInterfaceMethod (Type t, string name, Type ret_type, Type [] args)
 302                 {
 303                         return InterfaceMethod (t, name, ret_type, args, Operation.Lookup, null);
 304                 }
 305
 306                 public MethodInfo IsInterfaceIndexer (Type t, Type ret_type, Type [] args)
 307                 {
 308                         return InterfaceMethod (t, null, ret_type, args, Operation.Lookup, null);
 309                 }
 310
 311                 public void ImplementMethod (Type t, string name, Type ret_type, Type [] args, bool clear_one)
 312                 {
 313                         InterfaceMethod (t, name, ret_type, args,
 314                                          clear_one ? Operation.ClearOne : Operation.ClearAll, null);
 315                 }
 316
 317                 public void ImplementIndexer (Type t, MethodInfo mi, Type ret_type, Type [] args, bool clear_one)
 318                 {
 319                         InterfaceMethod (t, mi.Name, ret_type, args,
 320                                          clear_one ? Operation.ClearOne : Operation.ClearAll, mi);
 321                 }
 322
 323                 /// <remarks>
 324                 ///   If a method in Type `t' (or null to look in all interfaces
 325                 ///   and the base abstract class) with name `Name', return type `ret_type' and
 326                 ///   arguments `args' implements an interface, this method will
 327                 ///   return the MethodInfo that this method implements.
 328                 ///
 329                 ///   If `name' is null, we operate solely on the method's signature.  This is for
 330                 ///   instance used when implementing indexers.
 331                 ///
 332                 ///   The `Operation op' controls whether to lookup, clear the pending bit, or clear
 333                 ///   all the methods with the given signature.
 334                 ///
 335                 ///   The `MethodInfo need_proxy' is used when we're implementing an interface's
 336                 ///   indexer in a class.  If the new indexer's IndexerName does not match the one
 337                 ///   that was used in the interface, then we always need to create a proxy for it.
 338                 ///
 339                 /// </remarks>
 340                 public MethodInfo InterfaceMethod (Type t, string name, Type ret_type, Type [] args,
 341                                                    Operation op, MethodInfo need_proxy)
 342                 {
 343                         int arg_len = args.Length;
 344
 345                         if (pending_implementations == null)
 346                                 return null;
 347
 348                         foreach (TypeAndMethods tm in pending_implementations){
 349                                 if (!(t == null || tm.type == t))
 350                                         continue;
 351
 352                                 int method_count = tm.methods.Length;
 353                                 MethodInfo m;
 354                                 for (int i = 0; i < method_count; i++){
 355                                         m = tm.methods [i];
 356
 357                                         if (m == null)
 358                                                 continue;
 359
 360                                         // `need_proxy' is not null when we're implementing an
 361                                         // interface indexer and this is Clear(One/All) operation.
 362                                         // If `name' is null, then we do a match solely based on the
 363                                         // signature and not on the name (this is done in the Lookup
 364                                         // for an interface indexer).
 365                                         if ((name != null) && (need_proxy == null) && (name != m.Name))
 366                                                 continue;
 367
 368                                         if (ret_type != m.ReturnType){
 369                                                 if (!((ret_type == null && m.ReturnType == TypeManager.void_type) ||
 370                                                       (m.ReturnType == null && ret_type == TypeManager.void_type)))
 371                                                         continue;
 372                                         }
 373
 374                                         //
 375                                         // Check if we have the same parameters
 376                                         //
 377                                         if (tm.args [i].Length != arg_len)
 378                                                 continue;
 379
 380                                         int j, top = args.Length;
 381                                         bool fail = false;
 382
 383                                         for (j = 0; j < top; j++){
 384                                                 if (tm.args [i][j] != args[j]){
 385                                                         fail = true;
 386                                                         break;
 387                                                 }
 388                                         }
 389                                         if (fail)
 390                                                 continue;
 391
 392                                         if (op != Operation.Lookup){
 393                                                 // If `t != null', then this is an explicitly interface
 394                                                 // implementation and we can always clear the method.
 395                                                 // `need_proxy' is not null if we're implementing an
 396                                                 // interface indexer.  In this case, we need to create
 397                                                 // a proxy if the implementation's IndexerName doesn't
 398                                                 // match the IndexerName in the interface.
 399                                                 if ((t == null) && (need_proxy != null) && (name != m.Name))
 400                                                         tm.need_proxy [i] = need_proxy;
 401                                                 else
 402                                                         tm.methods [i] = null;
 403                                         }
 404                                         tm.found [i] = true;
 405
 406                                         //
 407                                         // Lookups and ClearOne return
 408                                         //
 409                                         if (op != Operation.ClearAll)
 410                                                 return m;
 411                                 }
 412
 413                                 // If a specific type was requested, we can stop now.
 414                                 if (tm.type == t)
 415                                         return null;
 416                         }
 417                         return null;
 418                 }
 419
 420                 /// <summary>
 421                 ///   C# allows this kind of scenarios:
 422                 ///   interface I { void M (); }
 423                 ///   class X { public void M (); }
 424                 ///   class Y : X, I { }
 425                 ///
 426                 ///   For that case, we create an explicit implementation function
 427                 ///   I.M in Y.
 428                 /// </summary>
 429                 void DefineProxy (Type iface, MethodInfo parent_method, MethodInfo iface_method,
 430                                   Type [] args)
 431                 {
 432                         MethodBuilder proxy;
 433
 434                         string proxy_name = iface.Name + "." + iface_method.Name;
 435
 436                         proxy = container.TypeBuilder.DefineMethod (
 437                                 proxy_name,
 438                                 MethodAttributes.HideBySig |
 439                                 MethodAttributes.NewSlot |
 440                                 MethodAttributes.Virtual,
 441                                 CallingConventions.Standard | CallingConventions.HasThis,
 442                                 parent_method.ReturnType, args);
 443
 444                         int top = args.Length;
 445                         ILGenerator ig = proxy.GetILGenerator ();
 446
 447                         ig.Emit (OpCodes.Ldarg_0);
 448                         for (int i = 0; i < top; i++){
 449                                 switch (i){
 450                                 case 0:
 451                                         ig.Emit (OpCodes.Ldarg_1); break;
 452                                 case 1:
 453                                         ig.Emit (OpCodes.Ldarg_2); break;
 454                                 case 2:
 455                                         ig.Emit (OpCodes.Ldarg_3); break;
 456                                 default:
 457                                         ig.Emit (OpCodes.Ldarg, i - 1); break;
 458                                 }
 459                         }
 460                         ig.Emit (OpCodes.Call, parent_method);
 461                         ig.Emit (OpCodes.Ret);
 462
 463                         container.TypeBuilder.DefineMethodOverride (proxy, iface_method);
 464                 }
 465
 466                 /// <summary>
 467                 ///   This function tells whether one of our parent classes implements
 468                 ///   the given method (which turns out, it is valid to have an interface
 469                 ///   implementation in a parent
 470                 /// </summary>
 471                 bool ParentImplements (Type iface_type, MethodInfo mi)
 472                 {
 473                         MethodSignature ms;
 474
 475                         Type [] args = TypeManager.GetArgumentTypes (mi);
 476                         ms = new MethodSignature (mi.Name, mi.ReturnType, args);
 477                         MemberList list = TypeContainer.FindMembers (
 478                                 container.TypeBuilder.BaseType, MemberTypes.Method | MemberTypes.Property,
 479                                 BindingFlags.Public | BindingFlags.Instance,
 480                                 MethodSignature.method_signature_filter, ms);
 481
 482                         if (list.Count == 0)
 483                                 return false;
 484
 485                         MethodInfo parent = (MethodInfo) list [0];
 486                         if (!parent.IsAbstract)
 487                                 DefineProxy (iface_type, parent, mi, args);
 488                         return true;
 489                 }
 490
 491                 /// <summary>
 492                 ///   Verifies that any pending abstract methods or interface methods
 493                 ///   were implemented.
 494                 /// </summary>
 495                 public bool VerifyPendingMethods ()
 496                 {
 497                         int top = pending_implementations.Length;
 498                         bool errors = false;
 499                         int i;
 500
 501                         for (i = 0; i < top; i++){
 502                                 Type type = pending_implementations [i].type;
 503                                 int j = 0;
 504
 505                                 foreach (MethodInfo mi in pending_implementations [i].methods){
 506                                         if (mi == null)
 507                                                 continue;
 508
 509                                         if (type.IsInterface){
 510                                                 MethodInfo need_proxy =
 511                                                         pending_implementations [i].need_proxy [j];
 512
 513                                                 if (need_proxy != null) {
 514                                                         Type [] args = TypeManager.GetArgumentTypes (mi);
 515                                                         DefineProxy (type, need_proxy, mi, args);
 516                                                         continue;
 517                                                 }
 518
 519                                                 if (ParentImplements (type, mi))
 520                                                         continue;
 521
 522                                                 if (pending_implementations [i].optional)
 523                                                         continue;
 524
 525                                                 string extra = "";
 526
 527                                                 if (pending_implementations [i].found [j])
 528                                                         extra = ".  (method might be non-public or static)";
 529                                                 Report.Error (
 530                                                         536, container.Location,
 531                                                         "`" + container.Name + "' does not implement " +
 532                                                         "interface member `" +
 533                                                         type.FullName + "." + mi.Name + "'" + extra);
 534                                         } else {
 535                                                 Report.Error (
 536                                                         534, container.Location,
 537                                                         "`" + container.Name + "' does not implement " +
 538                                                         "inherited abstract member `" +
 539                                                         type.FullName + "." + mi.Name + "'");
 540                                         }
 541                                         errors = true;
 542                                         j++;
 543                                 }
 544                         }
 545                         return errors;
 546                 }
 547         } /* end of class */
 548 }