mcs/mcs/namespace.cs

   1 //
   2 // namespace.cs: Tracks namespaces
   3 //
   4 // Author:
   5 //   Miguel de Icaza (miguel@ximian.com)
   6 //   Marek Safar (marek.safar@seznam.cz)
   7 //
   8 // Copyright 2001 Ximian, Inc.
   9 // Copyright 2003-2008 Novell, Inc.
  10 //
  11 using System;
  12 using System.Collections.Generic;
  13 using System.Linq;
  14
  15 namespace Mono.CSharp {
  16
  17         public class RootNamespace : Namespace {
  18
  19                 readonly string alias_name;
  20                 readonly Dictionary<string, Namespace> all_namespaces;
  21
  22                 public RootNamespace (string alias_name)
  23                         : base (null, String.Empty)
  24                 {
  25                         this.alias_name = alias_name;
  26
  27                         all_namespaces = new Dictionary<string, Namespace> ();
  28                         all_namespaces.Add ("", this);
  29                 }
  30
  31                 public string Alias {
  32                         get {
  33                                 return alias_name;
  34                         }
  35                 }
  36
  37                 public void RegisterNamespace (Namespace child)
  38                 {
  39                         if (child != this)
  40                                 all_namespaces.Add (child.Name, child);
  41                 }
  42
  43                 public bool IsNamespace (string name)
  44                 {
  45                         return all_namespaces.ContainsKey (name);
  46                 }
  47
  48                 protected void RegisterNamespace (string dotted_name)
  49                 {
  50                         if (dotted_name != null && dotted_name.Length != 0 && ! IsNamespace (dotted_name))
  51                                 GetNamespace (dotted_name, true);
  52                 }
  53
  54                 public override string GetSignatureForError ()
  55                 {
  56                         return alias_name + "::";
  57                 }
  58         }
  59
  60         public class GlobalRootNamespace : RootNamespace
  61         {
  62                 public GlobalRootNamespace ()
  63                         : base ("global")
  64                 {
  65                 }
  66
  67                 public override void Error_NamespaceDoesNotExist (Location loc, string name, int arity, IMemberContext ctx)
  68                 {
  69                         ctx.Module.Compiler.Report.Error (400, loc,
  70                                 "The type or namespace name `{0}' could not be found in the global namespace (are you missing an assembly reference?)",
  71                                 name);
  72                 }
  73         }
  74
  75         /// <summary>
  76         ///   Keeps track of the namespaces defined in the C# code.
  77         ///
  78         ///   This is an Expression to allow it to be referenced in the
  79         ///   compiler parse/intermediate tree during name resolution.
  80         /// </summary>
  81         public class Namespace : FullNamedExpression {
  82
  83                 Namespace parent;
  84                 string fullname;
  85                 protected Dictionary<string, Namespace> namespaces;
  86                 protected Dictionary<string, IList<TypeSpec>> types;
  87                 Dictionary<string, TypeExpr> cached_types;
  88                 RootNamespace root;
  89                 bool cls_checked;
  90
  91                 public readonly MemberName MemberName;
  92
  93                 /// <summary>
  94                 ///   Constructor Takes the current namespace and the
  95                 ///   name.  This is bootstrapped with parent == null
  96                 ///   and name = ""
  97                 /// </summary>
  98                 public Namespace (Namespace parent, string name)
  99                 {
 100                         // Expression members.
 101                         this.eclass = ExprClass.Namespace;
 102                         this.Type = InternalType.FakeInternalType;
 103                         this.loc = Location.Null;
 104
 105                         this.parent = parent;
 106
 107                         if (parent != null)
 108                                 this.root = parent.root;
 109                         else
 110                                 this.root = this as RootNamespace;
 111
 112                         if (this.root == null)
 113                                 throw new InternalErrorException ("Root namespaces must be created using RootNamespace");
 114
 115                         string pname = parent != null ? parent.fullname : "";
 116
 117                         if (pname == "")
 118                                 fullname = name;
 119                         else
 120                                 fullname = parent.fullname + "." + name;
 121
 122                         if (fullname == null)
 123                                 throw new InternalErrorException ("Namespace has a null fullname");
 124
 125                         if (parent != null && parent.MemberName != MemberName.Null)
 126                                 MemberName = new MemberName (parent.MemberName, name);
 127                         else if (name.Length == 0)
 128                                 MemberName = MemberName.Null;
 129                         else
 130                                 MemberName = new MemberName (name);
 131
 132                         namespaces = new Dictionary<string, Namespace> ();
 133                         cached_types = new Dictionary<string, TypeExpr> ();
 134
 135                         root.RegisterNamespace (this);
 136                 }
 137
 138                 #region Properties
 139
 140                 /// <summary>
 141                 ///   The qualified name of the current namespace
 142                 /// </summary>
 143                 public string Name {
 144                         get { return fullname; }
 145                 }
 146
 147                 /// <summary>
 148                 ///   The parent of this namespace, used by the parser to "Pop"
 149                 ///   the current namespace declaration
 150                 /// </summary>
 151                 public Namespace Parent {
 152                         get { return parent; }
 153                 }
 154
 155                 #endregion
 156
 157                 protected override Expression DoResolve (ResolveContext ec)
 158                 {
 159                         return this;
 160                 }
 161
 162                 public virtual void Error_NamespaceDoesNotExist (Location loc, string name, int arity, IMemberContext ctx)
 163                 {
 164                         FullNamedExpression retval = Lookup (ctx, name, -System.Math.Max (1, arity), loc);
 165                         if (retval != null) {
 166                                 Error_TypeArgumentsCannotBeUsed (ctx.Module.Compiler.Report, loc, retval.Type, arity);
 167                                 return;
 168                         }
 169
 170                         Namespace ns;
 171                         if (arity > 0 && namespaces.TryGetValue (name, out ns)) {
 172                                 ns.Error_TypeArgumentsCannotBeUsed (ctx.Module.Compiler.Report, loc, null, arity);
 173                                 return;
 174                         }
 175
 176                         ctx.Module.Compiler.Report.Error (234, loc,
 177                                 "The type or namespace name `{0}' does not exist in the namespace `{1}'. Are you missing an assembly reference?",
 178                                 name, GetSignatureForError ());
 179                 }
 180
 181                 public override string GetSignatureForError ()
 182                 {
 183                         return fullname;
 184                 }
 185
 186                 public Namespace GetNamespace (string name, bool create)
 187                 {
 188                         int pos = name.IndexOf ('.');
 189
 190                         Namespace ns;
 191                         string first;
 192                         if (pos >= 0)
 193                                 first = name.Substring (0, pos);
 194                         else
 195                                 first = name;
 196
 197                         if (!namespaces.TryGetValue (first, out ns)) {
 198                                 if (!create)
 199                                         return null;
 200
 201                                 ns = new Namespace (this, first);
 202                                 namespaces.Add (first, ns);
 203                         }
 204
 205                         if (pos >= 0)
 206                                 ns = ns.GetNamespace (name.Substring (pos + 1), create);
 207
 208                         return ns;
 209                 }
 210
 211                 public TypeExpr LookupType (IMemberContext ctx, string name, int arity, bool silent, Location loc)
 212                 {
 213                         if (types == null)
 214                                 return null;
 215
 216                         TypeExpr te;
 217                         if (arity == 0 && cached_types.TryGetValue (name, out te))
 218                                 return te;
 219
 220                         IList<TypeSpec> found;
 221                         if (!types.TryGetValue (name, out found))
 222                                 return null;
 223
 224                         TypeSpec best = null;
 225                         foreach (var ts in found) {
 226                                 if (ts.Arity == arity) {
 227                                         if (best == null) {
 228                                                 best = ts;
 229                                                 continue;
 230                                         }
 231
 232                                         var pts = best as BuildinTypeSpec;
 233                                         if (pts == null)
 234                                                 pts = ts as BuildinTypeSpec;
 235
 236                                         if (pts != null) {
 237                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (best);
 238                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
 239
 240                                                 // TODO: This should use different warning number but we want to be csc compatible
 241                                                 ctx.Module.Compiler.Report.Warning (1685, 1, loc,
 242                                                         "The predefined type `{0}.{1}' is redefined in the source code. Ignoring the local type definition",
 243                                                         pts.Namespace, pts.Name);
 244                                                 best = pts;
 245                                                 continue;
 246                                         }
 247
 248                                         if (best.MemberDefinition.IsImported && ts.MemberDefinition.IsImported) {
 249                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (best);
 250                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
 251                                                 if (silent) {
 252                                                         ctx.Module.Compiler.Report.Warning (1685, 1, loc,
 253                                                                 "The predefined type `{0}' is defined in multiple assemblies. Using definition from `{1}'",
 254                                                                 ts.GetSignatureForError (), best.MemberDefinition.DeclaringAssembly.Name);
 255                                                 } else {
 256                                                         ctx.Module.Compiler.Report.Error (433, loc, "The imported type `{0}' is defined multiple times", ts.GetSignatureForError ());
 257                                                 }
 258
 259                                                 break;
 260                                         }
 261
 262                                         if (best.MemberDefinition.IsImported)
 263                                                 best = ts;
 264
 265                                         if ((best.Modifiers & Modifiers.INTERNAL) != 0 && !best.MemberDefinition.IsInternalAsPublic (RootContext.ToplevelTypes.DeclaringAssembly))
 266                                                 continue;
 267
 268                                         if (silent)
 269                                                 continue;
 270
 271                                         if (ts.MemberDefinition.IsImported)
 272                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
 273
 274                                         ctx.Module.Compiler.Report.Warning (436, 2, loc,
 275                                                 "The type `{0}' conflicts with the imported type of same name'. Ignoring the imported type definition",
 276                                                 best.GetSignatureForError ());
 277                                 }
 278
 279                                 //
 280                                 // Lookup for the best candidate with closest arity match
 281                                 //
 282                                 if (arity < 0) {
 283                                         if (best == null) {
 284                                                 best = ts;
 285                                         } else if (System.Math.Abs (ts.Arity + arity) < System.Math.Abs (best.Arity + arity)) {
 286                                                 best = ts;
 287                                         }
 288                                 }
 289                         }
 290
 291                         if (best == null)
 292                                 return null;
 293
 294                         if ((best.Modifiers & Modifiers.INTERNAL) != 0 && !best.MemberDefinition.IsInternalAsPublic (RootContext.ToplevelTypes.DeclaringAssembly))
 295                                 return null;
 296
 297                         te = new TypeExpression (best, Location.Null);
 298
 299                         // TODO MemberCache: Cache more
 300                         if (arity == 0 && !silent)
 301                                 cached_types.Add (name, te);
 302
 303                         return te;
 304                 }
 305
 306                 TypeSpec LookupType (string name, int arity)
 307                 {
 308                         if (types == null)
 309                                 return null;
 310
 311                         IList<TypeSpec> found;
 312                         if (types.TryGetValue (name, out found)) {
 313                                 TypeSpec best = null;
 314
 315                                 foreach (var ts in found) {
 316                                         if (ts.Arity == arity)
 317                                                 return ts;
 318
 319                                         //
 320                                         // Lookup for the best candidate with closest arity match
 321                                         //
 322                                         if (arity < 0) {
 323                                                 if (best == null) {
 324                                                         best = ts;
 325                                                 } else if (System.Math.Abs (ts.Arity + arity) < System.Math.Abs (best.Arity + arity)) {
 326                                                         best = ts;
 327                                                 }
 328                                         }
 329                                 }
 330
 331                                 return best;
 332                         }
 333
 334                         return null;
 335                 }
 336
 337                 public FullNamedExpression Lookup (IMemberContext ctx, string name, int arity, Location loc)
 338                 {
 339                         if (arity == 0 && namespaces.ContainsKey (name))
 340                                 return namespaces [name];
 341
 342                         return LookupType (ctx, name, arity, false, loc);
 343                 }
 344
 345                 //
 346                 // Completes types with the given `prefix'
 347                 //
 348                 public IEnumerable<string> CompletionGetTypesStartingWith (string prefix)
 349                 {
 350                         if (types == null)
 351                                 return Enumerable.Empty<string> ();
 352
 353                         var res = from item in types
 354                                           where item.Key.StartsWith (prefix) && item.Value.Any (l => (l.Modifiers & Modifiers.PUBLIC) != 0)
 355                                           select item.Key;
 356
 357                         if (namespaces != null)
 358                                 res = res.Concat (from item in namespaces where item.Key.StartsWith (prefix) select item.Key);
 359
 360                         return res;
 361                 }
 362
 363                 ///
 364                 /// Looks for extension method in this namespace
 365                 ///
 366                 public List<MethodSpec> LookupExtensionMethod (TypeSpec extensionType, TypeContainer invocationContext, string name, int arity)
 367                 {
 368                         if (types == null)
 369                                 return null;
 370
 371                         List<MethodSpec> found = null;
 372
 373                         // TODO: Add per namespace flag when at least 1 type has extension
 374
 375                         foreach (var tgroup in types.Values) {
 376                                 foreach (var ts in tgroup) {
 377                                         if ((ts.Modifiers & Modifiers.METHOD_EXTENSION) == 0)
 378                                                 continue;
 379
 380                                         var res = ts.MemberCache.FindExtensionMethods (invocationContext, extensionType, name, arity);
 381                                         if (res == null)
 382                                                 continue;
 383
 384                                         if (found == null) {
 385                                                 found = res;
 386                                         } else {
 387                                                 found.AddRange (res);
 388                                         }
 389                                 }
 390                         }
 391
 392                         return found;
 393                 }
 394
 395                 public void AddType (TypeSpec ts)
 396                 {
 397                         if (types == null) {
 398                                 types = new Dictionary<string, IList<TypeSpec>> (64);
 399                         }
 400
 401                         var name = ts.Name;
 402                         IList<TypeSpec> existing;
 403                         if (types.TryGetValue (name, out existing)) {
 404                                 TypeSpec better_type;
 405                                 TypeSpec found;
 406                                 if (existing.Count == 1) {
 407                                         found = existing[0];
 408                                         if (ts.Arity == found.Arity) {
 409                                                 better_type = IsImportedTypeOverride (ts, found);
 410                                                 if (better_type == found)
 411                                                         return;
 412
 413                                                 if (better_type != null) {
 414                                                         existing [0] = better_type;
 415                                                         return;
 416                                                 }
 417                                         }
 418
 419                                         existing = new List<TypeSpec> ();
 420                                         existing.Add (found);
 421                                         types[name] = existing;
 422                                 } else {
 423                                         for (int i = 0; i < existing.Count; ++i) {
 424                                                 found = existing[i];
 425                                                 if (ts.Arity != found.Arity)
 426                                                         continue;
 427
 428                                                 better_type = IsImportedTypeOverride (ts, found);
 429                                                 if (better_type == found)
 430                                                         return;
 431
 432                                                 if (better_type != null) {
 433                                                         existing.RemoveAt (i);
 434                                                         --i;
 435                                                         continue;
 436                                                 }
 437                                         }
 438                                 }
 439
 440                                 existing.Add (ts);
 441                         } else {
 442                                 types.Add (name, new TypeSpec[] { ts });
 443                         }
 444                 }
 445
 446                 //
 447                 // We import any types but in the situation there are same types
 448                 // but one has better visibility (either public or internal with friend)
 449                 // the less visible type is removed from the namespace cache
 450                 //
 451                 public static TypeSpec IsImportedTypeOverride (TypeSpec ts, TypeSpec found)
 452                 {
 453                         var ts_accessible = (ts.Modifiers & Modifiers.PUBLIC) != 0 || ts.MemberDefinition.IsInternalAsPublic (RootContext.ToplevelTypes.DeclaringAssembly);
 454                         var found_accessible = (found.Modifiers & Modifiers.PUBLIC) != 0 || found.MemberDefinition.IsInternalAsPublic (RootContext.ToplevelTypes.DeclaringAssembly);
 455
 456                         if (ts_accessible && !found_accessible)
 457                                 return ts;
 458
 459                         // found is better always better for accessible or inaccessible ts
 460                         if (!ts_accessible)
 461                                 return found;
 462
 463                         return null;
 464                 }
 465
 466                 public void RemoveDeclSpace (string name)
 467                 {
 468                         types.Remove (name);
 469                 }
 470
 471                 public void ReplaceTypeWithPredefined (TypeSpec ts, BuildinTypeSpec pts)
 472                 {
 473                         var found = types [ts.Name];
 474                         cached_types.Remove (ts.Name);
 475                         if (found.Count == 1) {
 476                                 types[ts.Name][0] = pts;
 477                         } else {
 478                                 throw new NotImplementedException ();
 479                         }
 480                 }
 481
 482                 public void VerifyClsCompliance ()
 483                 {
 484                         if (types == null || cls_checked)
 485                                 return;
 486
 487                         cls_checked = true;
 488
 489                         // TODO: This is quite ugly way to check for CLS compliance at namespace level
 490
 491                         var locase_types = new Dictionary<string, List<TypeSpec>> (StringComparer.OrdinalIgnoreCase);
 492                         foreach (var tgroup in types.Values) {
 493                                 foreach (var tm in tgroup) {
 494                                         if ((tm.Modifiers & Modifiers.PUBLIC) == 0 || !tm.IsCLSCompliant ())
 495                                                 continue;
 496
 497                                         List<TypeSpec> found;
 498                                         if (!locase_types.TryGetValue (tm.Name, out found)) {
 499                                                 found = new List<TypeSpec> ();
 500                                                 locase_types.Add (tm.Name, found);
 501                                         }
 502
 503                                         found.Add (tm);
 504                                 }
 505                         }
 506
 507                         foreach (var locase in locase_types.Values) {
 508                                 if (locase.Count < 2)
 509                                         continue;
 510
 511                                 bool all_same = true;
 512                                 foreach (var notcompliant in locase) {
 513                                         all_same = notcompliant.Name == locase[0].Name;
 514                                         if (!all_same)
 515                                                 break;
 516                                 }
 517
 518                                 if (all_same)
 519                                         continue;
 520
 521                                 TypeContainer compiled = null;
 522                                 foreach (var notcompliant in locase) {
 523                                         if (!notcompliant.MemberDefinition.IsImported) {
 524                                                 if (compiled != null)
 525                                                         compiled.Compiler.Report.SymbolRelatedToPreviousError (compiled);
 526
 527                                                 compiled = notcompliant.MemberDefinition as TypeContainer;
 528                                         } else {
 529                                                 compiled.Compiler.Report.SymbolRelatedToPreviousError (notcompliant);
 530                                         }
 531                                 }
 532
 533                                 compiled.Compiler.Report.Warning (3005, 1, compiled.Location,
 534                                         "Identifier `{0}' differing only in case is not CLS-compliant", compiled.GetSignatureForError ());
 535                         }
 536                 }
 537         }
 538
 539         //
 540         // Namespace container as created by the parser
 541         //
 542         public class NamespaceEntry : IMemberContext {
 543
 544                 public class UsingEntry {
 545                         readonly MemberName name;
 546                         Namespace resolved;
 547
 548                         public UsingEntry (MemberName name)
 549                         {
 550                                 this.name = name;
 551                         }
 552
 553                         public string GetSignatureForError ()
 554                         {
 555                                 return name.GetSignatureForError ();
 556                         }
 557
 558                         public Location Location {
 559                                 get { return name.Location; }
 560                         }
 561
 562                         public MemberName MemberName {
 563                                 get { return name; }
 564                         }
 565
 566                         public string Name {
 567                                 get { return GetSignatureForError (); }
 568                         }
 569
 570                         public Namespace Resolve (IMemberContext rc)
 571                         {
 572                                 if (resolved != null)
 573                                         return resolved;
 574
 575                                 FullNamedExpression fne = name.GetTypeExpression ().ResolveAsTypeStep (rc, false);
 576                                 if (fne == null)
 577                                         return null;
 578
 579                                 resolved = fne as Namespace;
 580                                 if (resolved == null) {
 581                                         rc.Module.Compiler.Report.SymbolRelatedToPreviousError (fne.Type);
 582                                         rc.Module.Compiler.Report.Error (138, Location,
 583                                                 "`{0}' is a type not a namespace. A using namespace directive can only be applied to namespaces",
 584                                                 GetSignatureForError ());
 585                                 }
 586                                 return resolved;
 587                         }
 588
 589                         public override string ToString ()
 590                         {
 591                                 return Name;
 592                         }
 593                 }
 594
 595                 public class UsingAliasEntry {
 596                         public readonly string Alias;
 597                         public Location Location;
 598
 599                         public UsingAliasEntry (string alias, Location loc)
 600                         {
 601                                 this.Alias = alias;
 602                                 this.Location = loc;
 603                         }
 604
 605                         public virtual FullNamedExpression Resolve (IMemberContext rc, bool local)
 606                         {
 607                                 FullNamedExpression fne = rc.Module.GetRootNamespace (Alias);
 608                                 if (fne == null) {
 609                                         rc.Module.Compiler.Report.Error (430, Location,
 610                                                 "The extern alias `{0}' was not specified in -reference option",
 611                                                 Alias);
 612                                 }
 613
 614                                 return fne;
 615                         }
 616
 617                         public override string ToString ()
 618                         {
 619                                 return Alias;
 620                         }
 621
 622                 }
 623
 624                 class LocalUsingAliasEntry : UsingAliasEntry {
 625                         FullNamedExpression resolved;
 626                         MemberName value;
 627
 628                         public LocalUsingAliasEntry (string alias, MemberName name, Location loc)
 629                                 : base (alias, loc)
 630                         {
 631                                 this.value = name;
 632                         }
 633
 634                         public override FullNamedExpression Resolve (IMemberContext rc, bool local)
 635                         {
 636                                 if (resolved != null || value == null)
 637                                         return resolved;
 638
 639                                 if (local)
 640                                         return null;
 641
 642                                 resolved = value.GetTypeExpression ().ResolveAsTypeStep (rc, false);
 643                                 if (resolved == null) {
 644                                         value = null;
 645                                         return null;
 646                                 }
 647
 648                                 if (resolved is TypeExpr)
 649                                         resolved = resolved.ResolveAsTypeTerminal (rc, false);
 650
 651                                 return resolved;
 652                         }
 653
 654                         public override string ToString ()
 655                         {
 656                                 return String.Format ("{0} = {1}", Alias, value.GetSignatureForError ());
 657                         }
 658                 }
 659
 660                 Namespace ns;
 661                 NamespaceEntry parent, implicit_parent;
 662                 CompilationUnit file;
 663                 int symfile_id;
 664
 665                 // Namespace using import block
 666                 List<UsingAliasEntry> using_aliases;
 667                 List<UsingEntry> using_clauses;
 668                 public bool DeclarationFound;
 669                 // End
 670
 671                 public readonly bool IsImplicit;
 672                 public readonly DeclSpace SlaveDeclSpace;
 673                 static readonly Namespace [] empty_namespaces = new Namespace [0];
 674                 Namespace [] namespace_using_table;
 675                 ModuleContainer ctx;
 676
 677                 static List<NamespaceEntry> entries = new List<NamespaceEntry> ();
 678
 679                 public static void Reset ()
 680                 {
 681                         entries = new List<NamespaceEntry> ();
 682                 }
 683
 684                 public NamespaceEntry (ModuleContainer ctx, NamespaceEntry parent, CompilationUnit file, string name)
 685                 {
 686                         this.ctx = ctx;
 687                         this.parent = parent;
 688                         this.file = file;
 689                         entries.Add (this);
 690
 691                         if (parent != null)
 692                                 ns = parent.NS.GetNamespace (name, true);
 693                         else if (name != null)
 694                                 ns = ctx.GlobalRootNamespace.GetNamespace (name, true);
 695                         else
 696                                 ns = ctx.GlobalRootNamespace;
 697
 698                         SlaveDeclSpace = new RootDeclSpace (this);
 699                 }
 700
 701                 private NamespaceEntry (ModuleContainer ctx, NamespaceEntry parent, CompilationUnit file, Namespace ns, bool slave)
 702                 {
 703                         this.ctx = ctx;
 704                         this.parent = parent;
 705                         this.file = file;
 706                         this.IsImplicit = true;
 707                         this.ns = ns;
 708                         this.SlaveDeclSpace = slave ? new RootDeclSpace (this) : null;
 709                 }
 710
 711                 public List<UsingEntry> Usings {
 712                         get {
 713                                 return using_clauses;
 714                         }
 715                 }
 716
 717                 //
 718                 // Extracts the using alises and using clauses into a couple of
 719                 // arrays that might already have the same information;  Used by the
 720                 // C# Eval mode.
 721                 //
 722                 public void Extract (List<UsingAliasEntry> out_using_aliases, List<UsingEntry> out_using_clauses)
 723                 {
 724                         if (using_aliases != null){
 725                                 foreach (UsingAliasEntry uae in using_aliases){
 726                                         bool replaced = false;
 727
 728                                         for (int i = 0; i < out_using_aliases.Count; i++){
 729                                                 UsingAliasEntry out_uea = (UsingAliasEntry) out_using_aliases [i];
 730
 731                                                 if (out_uea.Alias == uae.Alias){
 732                                                         out_using_aliases [i] = uae;
 733                                                         replaced = true;
 734                                                         break;
 735                                                 }
 736                                         }
 737                                         if (!replaced)
 738                                                 out_using_aliases.Add (uae);
 739                                 }
 740                         }
 741
 742                         if (using_clauses != null){
 743                                 foreach (UsingEntry ue in using_clauses){
 744                                         bool found = false;
 745
 746                                         foreach (UsingEntry out_ue in out_using_clauses)
 747                                                 if (out_ue.Name == ue.Name){
 748                                                         found = true;
 749                                                         break;
 750                                                 }
 751                                         if (!found)
 752                                                 out_using_clauses.Add (ue);
 753                                 }
 754                         }
 755                 }
 756
 757                 //
 758                 // According to section 16.3.1 (using-alias-directive), the namespace-or-type-name is
 759                 // resolved as if the immediately containing namespace body has no using-directives.
 760                 //
 761                 // Section 16.3.2 says that the same rule is applied when resolving the namespace-name
 762                 // in the using-namespace-directive.
 763                 //
 764                 // To implement these rules, the expressions in the using directives are resolved using
 765                 // the "doppelganger" (ghostly bodiless duplicate).
 766                 //
 767                 NamespaceEntry doppelganger;
 768                 NamespaceEntry Doppelganger {
 769                         get {
 770                                 if (!IsImplicit && doppelganger == null) {
 771                                         doppelganger = new NamespaceEntry (ctx, ImplicitParent, file, ns, true);
 772                                         doppelganger.using_aliases = using_aliases;
 773                                 }
 774                                 return doppelganger;
 775                         }
 776                 }
 777
 778                 public Namespace NS {
 779                         get { return ns; }
 780                 }
 781
 782                 public NamespaceEntry Parent {
 783                         get { return parent; }
 784                 }
 785
 786                 public NamespaceEntry ImplicitParent {
 787                         get {
 788                                 if (parent == null)
 789                                         return null;
 790                                 if (implicit_parent == null) {
 791                                         implicit_parent = (parent.NS == ns.Parent)
 792                                                 ? parent
 793                                                 : new NamespaceEntry (ctx, parent, file, ns.Parent, false);
 794                                 }
 795                                 return implicit_parent;
 796                         }
 797                 }
 798
 799                 /// <summary>
 800                 ///   Records a new namespace for resolving name references
 801                 /// </summary>
 802                 public void AddUsing (MemberName name, Location loc)
 803                 {
 804                         if (DeclarationFound){
 805                                 Compiler.Report.Error (1529, loc, "A using clause must precede all other namespace elements except extern alias declarations");
 806                         }
 807
 808                         if (using_clauses == null) {
 809                                 using_clauses = new List<UsingEntry> ();
 810                         } else {
 811                                 foreach (UsingEntry old_entry in using_clauses) {
 812                                         if (name.Equals (old_entry.MemberName)) {
 813                                                 Compiler.Report.SymbolRelatedToPreviousError (old_entry.Location, old_entry.GetSignatureForError ());
 814                                                 Compiler.Report.Warning (105, 3, loc, "The using directive for `{0}' appeared previously in this namespace", name.GetSignatureForError ());
 815                                                 return;
 816                                         }
 817                                 }
 818                         }
 819
 820                         using_clauses.Add (new UsingEntry (name));
 821                 }
 822
 823                 public void AddUsingAlias (string alias, MemberName name, Location loc)
 824                 {
 825                         // TODO: This is parser bussines
 826                         if (DeclarationFound){
 827                                 Compiler.Report.Error (1529, loc, "A using clause must precede all other namespace elements except extern alias declarations");
 828                         }
 829
 830                         if (RootContext.Version != LanguageVersion.ISO_1 && alias == "global")
 831                                 Compiler.Report.Warning (440, 2, loc, "An alias named `global' will not be used when resolving 'global::';" +
 832                                         " the global namespace will be used instead");
 833
 834                         AddUsingAlias (new LocalUsingAliasEntry (alias, name, loc));
 835                 }
 836
 837                 public void AddUsingExternalAlias (string alias, Location loc, Report Report)
 838                 {
 839                         // TODO: Do this in parser
 840                         bool not_first = using_clauses != null || DeclarationFound;
 841                         if (using_aliases != null && !not_first) {
 842                                 foreach (UsingAliasEntry uae in using_aliases) {
 843                                         if (uae is LocalUsingAliasEntry) {
 844                                                 not_first = true;
 845                                                 break;
 846                                         }
 847                                 }
 848                         }
 849
 850                         if (not_first)
 851                                 Report.Error (439, loc, "An extern alias declaration must precede all other elements");
 852
 853                         if (alias == "global") {
 854                                 Error_GlobalNamespaceRedefined (loc, Report);
 855                                 return;
 856                         }
 857
 858                         AddUsingAlias (new UsingAliasEntry (alias, loc));
 859                 }
 860
 861                 void AddUsingAlias (UsingAliasEntry uae)
 862                 {
 863                         if (using_aliases == null) {
 864                                 using_aliases = new List<UsingAliasEntry> ();
 865                         } else {
 866                                 foreach (UsingAliasEntry entry in using_aliases) {
 867                                         if (uae.Alias == entry.Alias) {
 868                                                 Compiler.Report.SymbolRelatedToPreviousError (uae.Location, uae.Alias);
 869                                                 Compiler.Report.Error (1537, entry.Location, "The using alias `{0}' appeared previously in this namespace",
 870                                                         entry.Alias);
 871                                                 return;
 872                                         }
 873                                 }
 874                         }
 875
 876                         using_aliases.Add (uae);
 877                 }
 878
 879                 ///
 880                 /// Does extension methods look up to find a method which matches name and extensionType.
 881                 /// Search starts from this namespace and continues hierarchically up to top level.
 882                 ///
 883                 public IList<MethodSpec> LookupExtensionMethod (TypeSpec extensionType, string name, int arity, ref NamespaceEntry scope)
 884                 {
 885                         List<MethodSpec> candidates = null;
 886                         foreach (Namespace n in GetUsingTable ()) {
 887                                 var a = n.LookupExtensionMethod (extensionType, RootContext.ToplevelTypes, name, arity);
 888                                 if (a == null)
 889                                         continue;
 890
 891                                 if (candidates == null)
 892                                         candidates = a;
 893                                 else
 894                                         candidates.AddRange (a);
 895                         }
 896
 897                         scope = parent;
 898                         if (candidates != null)
 899                                 return candidates;
 900
 901                         if (parent == null)
 902                                 return null;
 903
 904                         //
 905                         // Inspect parent namespaces in namespace expression
 906                         //
 907                         Namespace parent_ns = ns.Parent;
 908                         do {
 909                                 candidates = parent_ns.LookupExtensionMethod (extensionType, RootContext.ToplevelTypes, name, arity);
 910                                 if (candidates != null)
 911                                         return candidates;
 912
 913                                 parent_ns = parent_ns.Parent;
 914                         } while (parent_ns != null);
 915
 916                         //
 917                         // Continue in parent scope
 918                         //
 919                         return parent.LookupExtensionMethod (extensionType, name, arity, ref scope);
 920                 }
 921
 922                 public FullNamedExpression LookupNamespaceOrType (string name, int arity, Location loc, bool ignore_cs0104)
 923                 {
 924                         // Precondition: Only simple names (no dots) will be looked up with this function.
 925                         FullNamedExpression resolved = null;
 926                         for (NamespaceEntry curr_ns = this; curr_ns != null; curr_ns = curr_ns.ImplicitParent) {
 927                                 if ((resolved = curr_ns.Lookup (name, arity, loc, ignore_cs0104)) != null)
 928                                         break;
 929                         }
 930
 931                         return resolved;
 932                 }
 933
 934                 public IList<string> CompletionGetTypesStartingWith (string prefix)
 935                 {
 936                         IEnumerable<string> all = Enumerable.Empty<string> ();
 937
 938                         for (NamespaceEntry curr_ns = this; curr_ns != null; curr_ns = curr_ns.ImplicitParent){
 939                                 foreach (Namespace using_ns in GetUsingTable ()){
 940                                         if (prefix.StartsWith (using_ns.Name)){
 941                                                 int ld = prefix.LastIndexOf ('.');
 942                                                 if (ld != -1){
 943                                                         string rest = prefix.Substring (ld+1);
 944
 945                                                         all = all.Concat (using_ns.CompletionGetTypesStartingWith (rest));
 946                                                 }
 947                                         }
 948                                         all = all.Concat (using_ns.CompletionGetTypesStartingWith (prefix));
 949                                 }
 950                         }
 951
 952                         return all.Distinct ().ToList ();
 953                 }
 954
 955                 // Looks-up a alias named @name in this and surrounding namespace declarations
 956                 public FullNamedExpression LookupNamespaceAlias (string name)
 957                 {
 958                         for (NamespaceEntry n = this; n != null; n = n.ImplicitParent) {
 959                                 if (n.using_aliases == null)
 960                                         continue;
 961
 962                                 foreach (UsingAliasEntry ue in n.using_aliases) {
 963                                         if (ue.Alias == name)
 964                                                 return ue.Resolve (Doppelganger ?? this, Doppelganger == null);
 965                                 }
 966                         }
 967
 968                         return null;
 969                 }
 970
 971                 private FullNamedExpression Lookup (string name, int arity, Location loc, bool ignore_cs0104)
 972                 {
 973                         //
 974                         // Check whether it's in the namespace.
 975                         //
 976                         FullNamedExpression fne = ns.Lookup (this, name, arity, loc);
 977
 978                         //
 979                         // Check aliases.
 980                         //
 981                         if (using_aliases != null && arity == 0) {
 982                                 foreach (UsingAliasEntry ue in using_aliases) {
 983                                         if (ue.Alias == name) {
 984                                                 if (fne != null) {
 985                                                         if (Doppelganger != null) {
 986                                                                 // TODO: Namespace has broken location
 987                                                                 //Report.SymbolRelatedToPreviousError (fne.Location, null);
 988                                                                 Compiler.Report.SymbolRelatedToPreviousError (ue.Location, null);
 989                                                                 Compiler.Report.Error (576, loc,
 990                                                                         "Namespace `{0}' contains a definition with same name as alias `{1}'",
 991                                                                         GetSignatureForError (), name);
 992                                                         } else {
 993                                                                 return fne;
 994                                                         }
 995                                                 }
 996
 997                                                 return ue.Resolve (Doppelganger ?? this, Doppelganger == null);
 998                                         }
 999                                 }
1000                         }
1001
1002                         if (fne != null) {
1003                                 if (!((fne.Type.Modifiers & Modifiers.INTERNAL) != 0 && !fne.Type.MemberDefinition.IsInternalAsPublic (RootContext.ToplevelTypes.DeclaringAssembly)))
1004                                         return fne;
1005                         }
1006
1007                         if (IsImplicit)
1008                                 return null;
1009
1010                         //
1011                         // Check using entries.
1012                         //
1013                         FullNamedExpression match = null;
1014                         foreach (Namespace using_ns in GetUsingTable ()) {
1015                                 // A using directive imports only types contained in the namespace, it
1016                                 // does not import any nested namespaces
1017                                 fne = using_ns.LookupType (this, name, arity, false, loc);
1018                                 if (fne == null)
1019                                         continue;
1020
1021                                 if (match == null) {
1022                                         match = fne;
1023                                         continue;
1024                                 }
1025
1026                                 // Prefer types over namespaces
1027                                 var texpr_fne = fne as TypeExpr;
1028                                 var texpr_match = match as TypeExpr;
1029                                 if (texpr_fne != null && texpr_match == null) {
1030                                         match = fne;
1031                                         continue;
1032                                 } else if (texpr_fne == null) {
1033                                         continue;
1034                                 }
1035
1036                                 if (ignore_cs0104)
1037                                         return match;
1038
1039                                 // It can be top level accessibility only
1040                                 var better = Namespace.IsImportedTypeOverride (texpr_match.Type, texpr_fne.Type);
1041                                 if (better == null) {
1042                                         Compiler.Report.SymbolRelatedToPreviousError (texpr_match.Type);
1043                                         Compiler.Report.SymbolRelatedToPreviousError (texpr_fne.Type);
1044                                         Compiler.Report.Error (104, loc, "`{0}' is an ambiguous reference between `{1}' and `{2}'",
1045                                                 name, texpr_match.GetSignatureForError (), texpr_fne.GetSignatureForError ());
1046                                         return match;
1047                                 }
1048
1049                                 if (better == texpr_fne.Type)
1050                                         match = texpr_fne;
1051                         }
1052
1053                         return match;
1054                 }
1055
1056                 Namespace [] GetUsingTable ()
1057                 {
1058                         if (namespace_using_table != null)
1059                                 return namespace_using_table;
1060
1061                         if (using_clauses == null) {
1062                                 namespace_using_table = empty_namespaces;
1063                                 return namespace_using_table;
1064                         }
1065
1066                         var list = new List<Namespace> (using_clauses.Count);
1067
1068                         foreach (UsingEntry ue in using_clauses) {
1069                                 Namespace using_ns = ue.Resolve (Doppelganger);
1070                                 if (using_ns == null)
1071                                         continue;
1072
1073                                 list.Add (using_ns);
1074                         }
1075
1076                         namespace_using_table = list.ToArray ();
1077                         return namespace_using_table;
1078                 }
1079
1080                 static readonly string [] empty_using_list = new string [0];
1081
1082                 public int SymbolFileID {
1083                         get {
1084                                 if (symfile_id == 0 && file.SourceFileEntry != null) {
1085                                         int parent_id = parent == null ? 0 : parent.SymbolFileID;
1086
1087                                         string [] using_list = empty_using_list;
1088                                         if (using_clauses != null) {
1089                                                 using_list = new string [using_clauses.Count];
1090                                                 for (int i = 0; i < using_clauses.Count; i++)
1091                                                         using_list [i] = ((UsingEntry) using_clauses [i]).MemberName.GetName ();
1092                                         }
1093
1094                                         symfile_id = SymbolWriter.DefineNamespace (ns.Name, file.CompileUnitEntry, using_list, parent_id);
1095                                 }
1096                                 return symfile_id;
1097                         }
1098                 }
1099
1100                 static void MsgtryRef (string s)
1101                 {
1102                         Console.WriteLine ("    Try using -r:" + s);
1103                 }
1104
1105                 static void MsgtryPkg (string s)
1106                 {
1107                         Console.WriteLine ("    Try using -pkg:" + s);
1108                 }
1109
1110                 public static void Error_GlobalNamespaceRedefined (Location loc, Report Report)
1111                 {
1112                         Report.Error (1681, loc, "The global extern alias cannot be redefined");
1113                 }
1114
1115                 public static void Error_NamespaceNotFound (Location loc, string name, Report Report)
1116                 {
1117                         Report.Error (246, loc, "The type or namespace name `{0}' could not be found. Are you missing a using directive or an assembly reference?",
1118                                 name);
1119
1120                         switch (name) {
1121                         case "Gtk": case "GtkSharp":
1122                                 MsgtryPkg ("gtk-sharp");
1123                                 break;
1124
1125                         case "Gdk": case "GdkSharp":
1126                                 MsgtryPkg ("gdk-sharp");
1127                                 break;
1128
1129                         case "Glade": case "GladeSharp":
1130                                 MsgtryPkg ("glade-sharp");
1131                                 break;
1132
1133                         case "System.Drawing":
1134                         case "System.Web.Services":
1135                         case "System.Web":
1136                         case "System.Data":
1137                         case "System.Windows.Forms":
1138                                 MsgtryRef (name);
1139                                 break;
1140                         }
1141                 }
1142
1143                 /// <summary>
1144                 ///   Used to validate that all the using clauses are correct
1145                 ///   after we are finished parsing all the files.
1146                 /// </summary>
1147                 void VerifyUsing ()
1148                 {
1149                         if (using_aliases != null) {
1150                                 foreach (UsingAliasEntry ue in using_aliases)
1151                                         ue.Resolve (Doppelganger, Doppelganger == null);
1152                         }
1153
1154                         if (using_clauses != null) {
1155                                 foreach (UsingEntry ue in using_clauses)
1156                                         ue.Resolve (Doppelganger);
1157                         }
1158                 }
1159
1160                 /// <summary>
1161                 ///   Used to validate that all the using clauses are correct
1162                 ///   after we are finished parsing all the files.
1163                 /// </summary>
1164                 static public void VerifyAllUsing ()
1165                 {
1166                         foreach (NamespaceEntry entry in entries)
1167                                 entry.VerifyUsing ();
1168                 }
1169
1170                 public string GetSignatureForError ()
1171                 {
1172                         return ns.GetSignatureForError ();
1173                 }
1174
1175                 public override string ToString ()
1176                 {
1177                         return ns.ToString ();
1178                 }
1179
1180                 #region IMemberContext Members
1181
1182                 public CompilerContext Compiler {
1183                         get { return ctx.Compiler; }
1184                 }
1185
1186                 public TypeSpec CurrentType {
1187                         get { return SlaveDeclSpace.CurrentType; }
1188                 }
1189
1190                 public MemberCore CurrentMemberDefinition {
1191                         get { return SlaveDeclSpace.CurrentMemberDefinition; }
1192                 }
1193
1194                 public TypeParameter[] CurrentTypeParameters {
1195                         get { return SlaveDeclSpace.CurrentTypeParameters; }
1196                 }
1197
1198                 // FIXME: It's false for expression types
1199                 public bool HasUnresolvedConstraints {
1200                         get { return true; }
1201                 }
1202
1203                 public bool IsObsolete {
1204                         get { return SlaveDeclSpace.IsObsolete; }
1205                 }
1206
1207                 public bool IsUnsafe {
1208                         get { return SlaveDeclSpace.IsUnsafe; }
1209                 }
1210
1211                 public bool IsStatic {
1212                         get { return SlaveDeclSpace.IsStatic; }
1213                 }
1214
1215                 public ModuleContainer Module {
1216                         get { return ctx; }
1217                 }
1218
1219                 #endregion
1220         }
1221 }