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