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 // Copyright 2011 Xamarin Inc
  11 //
  12 using System;
  13 using System.Collections.Generic;
  14 using System.Linq;
  15 using Mono.CompilerServices.SymbolWriter;
  16
  17 namespace Mono.CSharp {
  18
  19         public class RootNamespace : Namespace {
  20
  21                 readonly string alias_name;
  22                 readonly Dictionary<string, Namespace> all_namespaces;
  23
  24                 public RootNamespace (string alias_name)
  25                         : base ()
  26                 {
  27                         this.alias_name = alias_name;
  28                         RegisterNamespace (this);
  29
  30                         all_namespaces = new Dictionary<string, Namespace> ();
  31                         all_namespaces.Add ("", this);
  32                 }
  33
  34                 public string Alias {
  35                         get {
  36                                 return alias_name;
  37                         }
  38                 }
  39
  40                 public static void Error_GlobalNamespaceRedefined (Report report, Location loc)
  41                 {
  42                         report.Error (1681, loc, "The global extern alias cannot be redefined");
  43                 }
  44
  45                 //
  46                 // For better error reporting where we try to guess missing using directive
  47                 //
  48                 public List<string> FindTypeNamespaces (IMemberContext ctx, string name, int arity)
  49                 {
  50                         List<string> res = null;
  51
  52                         foreach (var ns in all_namespaces) {
  53                                 var type = ns.Value.LookupType (ctx, name, arity, LookupMode.Normal, Location.Null);
  54                                 if (type != null) {
  55                                         if (res == null)
  56                                                 res = new List<string> ();
  57
  58                                         res.Add (ns.Key);
  59                                 }
  60                         }
  61
  62                         return res;
  63                 }
  64
  65                 //
  66                 // For better error reporting where compiler tries to guess missing using directive
  67                 //
  68                 public List<string> FindExtensionMethodNamespaces (IMemberContext ctx, string name, int arity)
  69                 {
  70                         List<string> res = null;
  71
  72                         foreach (var ns in all_namespaces) {
  73                                 if (ns.Key.Length == 0)
  74                                         continue;
  75
  76                                 var methods = ns.Value.LookupExtensionMethod (ctx, name, arity);
  77                                 if (methods != null) {
  78                                         if (res == null)
  79                                                 res = new List<string> ();
  80
  81                                         res.Add (ns.Key);
  82                                 }
  83                         }
  84
  85                         return res;
  86                 }
  87
  88                 public void RegisterNamespace (Namespace child)
  89                 {
  90                         if (child != this)
  91                                 all_namespaces.Add (child.Name, child);
  92                 }
  93
  94                 public override string GetSignatureForError ()
  95                 {
  96                         return alias_name + "::";
  97                 }
  98         }
  99
 100         public sealed class GlobalRootNamespace : RootNamespace
 101         {
 102                 public GlobalRootNamespace ()
 103                         : base ("global")
 104                 {
 105                 }
 106         }
 107
 108         //
 109         // Namespace cache for imported and compiled namespaces
 110         //
 111         public class Namespace
 112         {
 113                 readonly Namespace parent;
 114                 string fullname;
 115                 protected Dictionary<string, Namespace> namespaces;
 116                 protected Dictionary<string, IList<TypeSpec>> types;
 117                 List<TypeSpec> extension_method_types;
 118                 Dictionary<string, TypeSpec> cached_types;
 119                 bool cls_checked;
 120
 121                 /// <summary>
 122                 ///   Constructor Takes the current namespace and the
 123                 ///   name.  This is bootstrapped with parent == null
 124                 ///   and name = ""
 125                 /// </summary>
 126                 public Namespace (Namespace parent, string name)
 127                         : this ()
 128                 {
 129                         if (name == null)
 130                                 throw new ArgumentNullException ("name");
 131
 132                         this.parent = parent;
 133
 134                         string pname = parent != null ? parent.fullname : null;
 135
 136                         if (pname == null)
 137                                 fullname = name;
 138                         else
 139                                 fullname = pname + "." + name;
 140
 141                         while (parent.parent != null)
 142                                 parent = parent.parent;
 143
 144                         var root = parent as RootNamespace;
 145                         if (root == null)
 146                                 throw new InternalErrorException ("Root namespaces must be created using RootNamespace");
 147
 148                         root.RegisterNamespace (this);
 149                 }
 150
 151                 protected Namespace ()
 152                 {
 153                         namespaces = new Dictionary<string, Namespace> ();
 154                         cached_types = new Dictionary<string, TypeSpec> ();
 155                 }
 156
 157                 #region Properties
 158
 159                 /// <summary>
 160                 ///   The qualified name of the current namespace
 161                 /// </summary>
 162                 public string Name {
 163                         get { return fullname; }
 164                 }
 165
 166                 /// <summary>
 167                 ///   The parent of this namespace, used by the parser to "Pop"
 168                 ///   the current namespace declaration
 169                 /// </summary>
 170                 public Namespace Parent {
 171                         get { return parent; }
 172                 }
 173
 174                 #endregion
 175
 176                 public Namespace AddNamespace (MemberName name)
 177                 {
 178                         var ns_parent = name.Left == null ? this : AddNamespace (name.Left);
 179                         return ns_parent.TryAddNamespace (name.Basename);
 180                 }
 181
 182                 Namespace TryAddNamespace (string name)
 183                 {
 184                         Namespace ns;
 185
 186                         if (!namespaces.TryGetValue (name, out ns)) {
 187                                 ns = new Namespace (this, name);
 188                                 namespaces.Add (name, ns);
 189                         }
 190
 191                         return ns;
 192                 }
 193
 194                 public bool TryGetNamespace (string name, out Namespace ns)
 195                 {
 196                         return namespaces.TryGetValue (name, out ns);
 197                 }
 198
 199                 // TODO: Replace with CreateNamespace where MemberName is created for the method call
 200                 public Namespace GetNamespace (string name, bool create)
 201                 {
 202                         int pos = name.IndexOf ('.');
 203
 204                         Namespace ns;
 205                         string first;
 206                         if (pos >= 0)
 207                                 first = name.Substring (0, pos);
 208                         else
 209                                 first = name;
 210
 211                         if (!namespaces.TryGetValue (first, out ns)) {
 212                                 if (!create)
 213                                         return null;
 214
 215                                 ns = new Namespace (this, first);
 216                                 namespaces.Add (first, ns);
 217                         }
 218
 219                         if (pos >= 0)
 220                                 ns = ns.GetNamespace (name.Substring (pos + 1), create);
 221
 222                         return ns;
 223                 }
 224
 225                 public IList<TypeSpec> GetAllTypes (string name)
 226                 {
 227                         IList<TypeSpec> found;
 228                         if (types == null || !types.TryGetValue (name, out found))
 229                                 return null;
 230
 231                         return found;
 232                 }
 233
 234                 public virtual string GetSignatureForError ()
 235                 {
 236                         return fullname;
 237                 }
 238
 239                 public TypeSpec LookupType (IMemberContext ctx, string name, int arity, LookupMode mode, Location loc)
 240                 {
 241                         if (types == null)
 242                                 return null;
 243
 244                         TypeSpec best = null;
 245                         if (arity == 0 && cached_types.TryGetValue (name, out best)) {
 246                                 if (best != null || mode != LookupMode.IgnoreAccessibility)
 247                                         return best;
 248                         }
 249
 250                         IList<TypeSpec> found;
 251                         if (!types.TryGetValue (name, out found))
 252                                 return null;
 253
 254                         foreach (var ts in found) {
 255                                 if (ts.Arity == arity) {
 256                                         if (best == null) {
 257                                                 if ((ts.Modifiers & Modifiers.INTERNAL) != 0 && !ts.MemberDefinition.IsInternalAsPublic (ctx.Module.DeclaringAssembly) && mode != LookupMode.IgnoreAccessibility)
 258                                                         continue;
 259
 260                                                 best = ts;
 261                                                 continue;
 262                                         }
 263
 264                                         if (best.MemberDefinition.IsImported && ts.MemberDefinition.IsImported) {
 265                                                 if (ts.Kind == MemberKind.MissingType)
 266                                                         continue;
 267
 268                                                 if (best.Kind == MemberKind.MissingType) {
 269                                                         best = ts;
 270                                                         continue;
 271                                                 }
 272
 273                                                 if (mode == LookupMode.Normal) {
 274                                                         ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (best);
 275                                                         ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
 276                                                         ctx.Module.Compiler.Report.Error (433, loc, "The imported type `{0}' is defined multiple times", ts.GetSignatureForError ());
 277                                                 }
 278
 279                                                 break;
 280                                         }
 281
 282                                         if (ts.Kind == MemberKind.MissingType)
 283                                                 continue;
 284
 285                                         if (best.MemberDefinition.IsImported)
 286                                                 best = ts;
 287
 288                                         if ((best.Modifiers & Modifiers.INTERNAL) != 0 && !best.MemberDefinition.IsInternalAsPublic (ctx.Module.DeclaringAssembly))
 289                                                 continue;
 290
 291                                         if (mode != LookupMode.Normal)
 292                                                 continue;
 293
 294                                         if (ts.MemberDefinition.IsImported) {
 295                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (best);
 296                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
 297                                         }
 298
 299                                         ctx.Module.Compiler.Report.Warning (436, 2, loc,
 300                                                 "The type `{0}' conflicts with the imported type of same name'. Ignoring the imported type definition",
 301                                                 best.GetSignatureForError ());
 302                                 }
 303
 304                                 //
 305                                 // Lookup for the best candidate with the closest arity match
 306                                 //
 307                                 if (arity < 0) {
 308                                         if (best == null) {
 309                                                 best = ts;
 310                                         } else if (System.Math.Abs (ts.Arity + arity) < System.Math.Abs (best.Arity + arity)) {
 311                                                 best = ts;
 312                                         }
 313                                 }
 314                         }
 315
 316                         // TODO MemberCache: Cache more
 317                         if (arity == 0 && mode == LookupMode.Normal)
 318                                 cached_types.Add (name, best);
 319
 320                         if (best != null) {
 321                                 var dep = best.GetMissingDependencies ();
 322                                 if (dep != null)
 323                                         ImportedTypeDefinition.Error_MissingDependency (ctx, dep, loc);
 324                         }
 325
 326                         return best;
 327                 }
 328
 329                 public FullNamedExpression LookupTypeOrNamespace (IMemberContext ctx, string name, int arity, LookupMode mode, Location loc)
 330                 {
 331                         var texpr = LookupType (ctx, name, arity, mode, loc);
 332
 333                         Namespace ns;
 334                         if (arity == 0 && namespaces.TryGetValue (name, out ns)) {
 335                                 if (texpr == null)
 336                                         return new NamespaceExpression (ns, loc);
 337
 338                                 if (mode != LookupMode.Probing) {
 339                                         //ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (texpr.Type);
 340                                         // ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ns.loc, "");
 341                                         ctx.Module.Compiler.Report.Warning (437, 2, loc,
 342                                                 "The type `{0}' conflicts with the imported namespace `{1}'. Using the definition found in the source file",
 343                                                 texpr.GetSignatureForError (), ns.GetSignatureForError ());
 344                                 }
 345
 346                                 if (texpr.MemberDefinition.IsImported)
 347                                         return new NamespaceExpression (ns, loc);
 348                         }
 349
 350                         if (texpr == null)
 351                                 return null;
 352
 353                         return new TypeExpression (texpr, loc);
 354                 }
 355
 356                 //
 357                 // Completes types with the given `prefix'
 358                 //
 359                 public IEnumerable<string> CompletionGetTypesStartingWith (string prefix)
 360                 {
 361                         if (types == null)
 362                                 return Enumerable.Empty<string> ();
 363
 364                         var res = from item in types
 365                                           where item.Key.StartsWith (prefix) && item.Value.Any (l => (l.Modifiers & Modifiers.PUBLIC) != 0)
 366                                           select item.Key;
 367
 368                         if (namespaces != null)
 369                                 res = res.Concat (from item in namespaces where item.Key.StartsWith (prefix) select item.Key);
 370
 371                         return res;
 372                 }
 373
 374                 //
 375                 // Looks for extension method in this namespace
 376                 //
 377                 public List<MethodSpec> LookupExtensionMethod (IMemberContext invocationContext, string name, int arity)
 378                 {
 379                         if (extension_method_types == null)
 380                                 return null;
 381
 382                         List<MethodSpec> found = null;
 383                         for (int i = 0; i < extension_method_types.Count; ++i) {
 384                                 var ts = extension_method_types[i];
 385
 386                                 //
 387                                 // When the list was built we didn't know what members the type
 388                                 // contains
 389                                 //
 390                                 if ((ts.Modifiers & Modifiers.METHOD_EXTENSION) == 0) {
 391                                         if (extension_method_types.Count == 1) {
 392                                                 extension_method_types = null;
 393                                                 return found;
 394                                         }
 395
 396                                         extension_method_types.RemoveAt (i--);
 397                                         continue;
 398                                 }
 399
 400                                 var res = ts.MemberCache.FindExtensionMethods (invocationContext, name, arity);
 401                                 if (res == null)
 402                                         continue;
 403
 404                                 if (found == null) {
 405                                         found = res;
 406                                 } else {
 407                                         found.AddRange (res);
 408                                 }
 409                         }
 410
 411                         return found;
 412                 }
 413
 414                 public void AddType (ModuleContainer module, TypeSpec ts)
 415                 {
 416                         if (types == null) {
 417                                 types = new Dictionary<string, IList<TypeSpec>> (64);
 418                         }
 419
 420                         if (ts.IsClass && ts.Arity == 0) {
 421                                 var extension_method_allowed = ts.MemberDefinition.IsImported ? (ts.Modifiers & Modifiers.METHOD_EXTENSION) != 0 : (ts.IsStatic || ts.MemberDefinition.IsPartial);
 422                                 if (extension_method_allowed) {
 423                                         if (extension_method_types == null)
 424                                                 extension_method_types = new List<TypeSpec> ();
 425
 426                                         extension_method_types.Add (ts);
 427                                 }
 428                         }
 429
 430                         var name = ts.Name;
 431                         IList<TypeSpec> existing;
 432                         if (types.TryGetValue (name, out existing)) {
 433                                 TypeSpec better_type;
 434                                 TypeSpec found;
 435                                 if (existing.Count == 1) {
 436                                         found = existing[0];
 437                                         if (ts.Arity == found.Arity) {
 438                                                 better_type = IsImportedTypeOverride (module, ts, found);
 439                                                 if (better_type == found)
 440                                                         return;
 441
 442                                                 if (better_type != null) {
 443                                                         existing [0] = better_type;
 444                                                         return;
 445                                                 }
 446                                         }
 447
 448                                         existing = new List<TypeSpec> ();
 449                                         existing.Add (found);
 450                                         types[name] = existing;
 451                                 } else {
 452                                         for (int i = 0; i < existing.Count; ++i) {
 453                                                 found = existing[i];
 454                                                 if (ts.Arity != found.Arity)
 455                                                         continue;
 456
 457                                                 better_type = IsImportedTypeOverride (module, ts, found);
 458                                                 if (better_type == found)
 459                                                         return;
 460
 461                                                 if (better_type != null) {
 462                                                         existing.RemoveAt (i);
 463                                                         --i;
 464                                                         continue;
 465                                                 }
 466                                         }
 467                                 }
 468
 469                                 existing.Add (ts);
 470                         } else {
 471                                 types.Add (name, new TypeSpec[] { ts });
 472                         }
 473                 }
 474
 475                 //
 476                 // We import any types but in the situation there are same types
 477                 // but one has better visibility (either public or internal with friend)
 478                 // the less visible type is removed from the namespace cache
 479                 //
 480                 public static TypeSpec IsImportedTypeOverride (ModuleContainer module, TypeSpec ts, TypeSpec found)
 481                 {
 482                         var ts_accessible = (ts.Modifiers & Modifiers.PUBLIC) != 0 || ts.MemberDefinition.IsInternalAsPublic (module.DeclaringAssembly);
 483                         var found_accessible = (found.Modifiers & Modifiers.PUBLIC) != 0 || found.MemberDefinition.IsInternalAsPublic (module.DeclaringAssembly);
 484
 485                         if (ts_accessible && !found_accessible)
 486                                 return ts;
 487
 488                         // found is better always better for accessible or inaccessible ts
 489                         if (!ts_accessible)
 490                                 return found;
 491
 492                         return null;
 493                 }
 494
 495                 public void RemoveContainer (TypeContainer tc)
 496                 {
 497                         IList<TypeSpec> found;
 498                         if (types.TryGetValue (tc.MemberName.Name, out found)) {
 499                                 for (int i = 0; i < found.Count; ++i) {
 500                                         if (tc.MemberName.Arity != found [i].Arity)
 501                                                 continue;
 502
 503                                         if (found.Count == 1)
 504                                                 types.Remove (tc.MemberName.Name);
 505                                         else
 506                                                 found.RemoveAt (i);
 507
 508                                         break;
 509                                 }
 510                         }
 511
 512                         cached_types.Remove (tc.MemberName.Basename);
 513                 }
 514
 515                 public void SetBuiltinType (BuiltinTypeSpec pts)
 516                 {
 517                         var found = types[pts.Name];
 518                         cached_types.Remove (pts.Name);
 519                         if (found.Count == 1) {
 520                                 types[pts.Name][0] = pts;
 521                         } else {
 522                                 throw new NotImplementedException ();
 523                         }
 524                 }
 525
 526                 public void VerifyClsCompliance ()
 527                 {
 528                         if (types == null || cls_checked)
 529                                 return;
 530
 531                         cls_checked = true;
 532
 533                         // TODO: This is quite ugly way to check for CLS compliance at namespace level
 534
 535                         var locase_types = new Dictionary<string, List<TypeSpec>> (StringComparer.OrdinalIgnoreCase);
 536                         foreach (var tgroup in types.Values) {
 537                                 foreach (var tm in tgroup) {
 538                                         if ((tm.Modifiers & Modifiers.PUBLIC) == 0 || !tm.IsCLSCompliant ())
 539                                                 continue;
 540
 541                                         List<TypeSpec> found;
 542                                         if (!locase_types.TryGetValue (tm.Name, out found)) {
 543                                                 found = new List<TypeSpec> ();
 544                                                 locase_types.Add (tm.Name, found);
 545                                         }
 546
 547                                         found.Add (tm);
 548                                 }
 549                         }
 550
 551                         foreach (var locase in locase_types.Values) {
 552                                 if (locase.Count < 2)
 553                                         continue;
 554
 555                                 bool all_same = true;
 556                                 foreach (var notcompliant in locase) {
 557                                         all_same = notcompliant.Name == locase[0].Name;
 558                                         if (!all_same)
 559                                                 break;
 560                                 }
 561
 562                                 if (all_same)
 563                                         continue;
 564
 565                                 TypeContainer compiled = null;
 566                                 foreach (var notcompliant in locase) {
 567                                         if (!notcompliant.MemberDefinition.IsImported) {
 568                                                 if (compiled != null)
 569                                                         compiled.Compiler.Report.SymbolRelatedToPreviousError (compiled);
 570
 571                                                 compiled = notcompliant.MemberDefinition as TypeContainer;
 572                                         } else {
 573                                                 compiled.Compiler.Report.SymbolRelatedToPreviousError (notcompliant);
 574                                         }
 575                                 }
 576
 577                                 compiled.Compiler.Report.Warning (3005, 1, compiled.Location,
 578                                         "Identifier `{0}' differing only in case is not CLS-compliant", compiled.GetSignatureForError ());
 579                         }
 580                 }
 581         }
 582
 583         public class CompilationSourceFile : NamespaceContainer
 584         {
 585                 readonly SourceFile file;
 586                 CompileUnitEntry comp_unit;
 587                 Dictionary<string, SourceFile> include_files;
 588                 Dictionary<string, bool> conditionals;
 589
 590                 public CompilationSourceFile (ModuleContainer parent, SourceFile sourceFile)
 591                         : this (parent)
 592                 {
 593                         this.file = sourceFile;
 594                 }
 595
 596                 public CompilationSourceFile (ModuleContainer parent)
 597                         : base (parent)
 598                 {
 599                 }
 600
 601                 public CompileUnitEntry SymbolUnitEntry {
 602                         get {
 603                                 return comp_unit;
 604                         }
 605                 }
 606
 607                 public string FileName {
 608                         get {
 609                                 return file.Name;
 610                         }
 611                 }
 612
 613                 public SourceFile SourceFile {
 614                         get {
 615                                 return file;
 616                         }
 617                 }
 618
 619                 public void AddIncludeFile (SourceFile file)
 620                 {
 621                         if (file == this.file)
 622                                 return;
 623
 624                         if (include_files == null)
 625                                 include_files = new Dictionary<string, SourceFile> ();
 626
 627                         if (!include_files.ContainsKey (file.FullPathName))
 628                                 include_files.Add (file.FullPathName, file);
 629                 }
 630
 631                 public void AddDefine (string value)
 632                 {
 633                         if (conditionals == null)
 634                                 conditionals = new Dictionary<string, bool> (2);
 635
 636                         conditionals[value] = true;
 637                 }
 638
 639                 public void AddUndefine (string value)
 640                 {
 641                         if (conditionals == null)
 642                                 conditionals = new Dictionary<string, bool> (2);
 643
 644                         conditionals[value] = false;
 645                 }
 646
 647                 public override void PrepareEmit ()
 648                 {
 649                         var sw = Module.DeclaringAssembly.SymbolWriter;
 650                         if (sw != null) {
 651                                 CreateUnitSymbolInfo (sw);
 652                         }
 653
 654                         base.PrepareEmit ();
 655                 }
 656
 657                 //
 658                 // Creates symbol file index in debug symbol file
 659                 //
 660                 void CreateUnitSymbolInfo (MonoSymbolFile symwriter)
 661                 {
 662                         var si = file.CreateSymbolInfo (symwriter);
 663                         comp_unit = new CompileUnitEntry (symwriter, si);
 664
 665                         if (include_files != null) {
 666                                 foreach (SourceFile include in include_files.Values) {
 667                                         si = include.CreateSymbolInfo (symwriter);
 668                                         comp_unit.AddFile (si);
 669                                 }
 670                         }
 671                 }
 672
 673                 public bool IsConditionalDefined (string value)
 674                 {
 675                         if (conditionals != null) {
 676                                 bool res;
 677                                 if (conditionals.TryGetValue (value, out res))
 678                                         return res;
 679
 680                                 // When conditional was undefined
 681                                 if (conditionals.ContainsKey (value))
 682                                         return false;
 683                         }
 684
 685                         return Compiler.Settings.IsConditionalSymbolDefined (value);
 686                 }
 687
 688                 public override void Accept (StructuralVisitor visitor)
 689                 {
 690                         visitor.Visit (this);
 691                 }
 692         }
 693
 694
 695         //
 696         // Namespace block as created by the parser
 697         //
 698         public class NamespaceContainer : TypeContainer, IMemberContext
 699         {
 700                 static readonly Namespace[] empty_namespaces = new Namespace[0];
 701
 702                 readonly Namespace ns;
 703
 704                 public new readonly NamespaceContainer Parent;
 705
 706                 List<UsingClause> clauses;
 707
 708                 // Used by parsed to check for parser errors
 709                 public bool DeclarationFound;
 710
 711                 Namespace[] namespace_using_table;
 712                 TypeSpec[] types_using_table;
 713                 Dictionary<string, UsingAliasNamespace> aliases;
 714
 715                 public NamespaceContainer (MemberName name, NamespaceContainer parent)
 716                         : base (parent, name, null, MemberKind.Namespace)
 717                 {
 718                         this.Parent = parent;
 719                         this.ns = parent.NS.AddNamespace (name);
 720
 721                         containers = new List<TypeContainer> ();
 722                 }
 723
 724                 protected NamespaceContainer (ModuleContainer parent)
 725                         : base (parent, null, null, MemberKind.Namespace)
 726                 {
 727                         ns = parent.GlobalRootNamespace;
 728                         containers = new List<TypeContainer> (2);
 729                 }
 730
 731                 #region Properties
 732
 733                 public override AttributeTargets AttributeTargets {
 734                         get {
 735                                 throw new NotSupportedException ();
 736                         }
 737                 }
 738
 739                 public override string DocCommentHeader {
 740                         get {
 741                                 throw new NotSupportedException ();
 742                         }
 743                 }
 744
 745                 public Namespace NS {
 746                         get {
 747                                 return ns;
 748                         }
 749                 }
 750
 751                 public List<UsingClause> Usings {
 752                         get {
 753                                 return clauses;
 754                         }
 755                 }
 756
 757                 public override string[] ValidAttributeTargets {
 758                         get {
 759                                 throw new NotSupportedException ();
 760                         }
 761                 }
 762
 763                 #endregion
 764
 765                 public void AddUsing (UsingClause un)
 766                 {
 767                         if (DeclarationFound){
 768                                 Compiler.Report.Error (1529, un.Location, "A using clause must precede all other namespace elements except extern alias declarations");
 769                         }
 770
 771                         if (clauses == null)
 772                                 clauses = new List<UsingClause> ();
 773
 774                         clauses.Add (un);
 775                 }
 776
 777                 public void AddUsing (UsingAliasNamespace un)
 778                 {
 779                         if (DeclarationFound){
 780                                 Compiler.Report.Error (1529, un.Location, "A using clause must precede all other namespace elements except extern alias declarations");
 781                         }
 782
 783                         AddAlias (un);
 784                 }
 785
 786                 void AddAlias (UsingAliasNamespace un)
 787                 {
 788                         if (clauses == null) {
 789                                 clauses = new List<UsingClause> ();
 790                         } else {
 791                                 foreach (var entry in clauses) {
 792                                         var a = entry as UsingAliasNamespace;
 793                                         if (a != null && a.Alias.Value == un.Alias.Value) {
 794                                                 Compiler.Report.SymbolRelatedToPreviousError (a.Location, "");
 795                                                 Compiler.Report.Error (1537, un.Location,
 796                                                         "The using alias `{0}' appeared previously in this namespace", un.Alias.Value);
 797                                         }
 798                                 }
 799                         }
 800
 801                         clauses.Add (un);
 802                 }
 803
 804                 public override void AddPartial (TypeDefinition next_part)
 805                 {
 806                         var existing = ns.LookupType (this, next_part.MemberName.Name, next_part.MemberName.Arity, LookupMode.Probing, Location.Null);
 807                         var td = existing != null ? existing.MemberDefinition as TypeDefinition : null;
 808                         AddPartial (next_part, td);
 809                 }
 810
 811                 public override void AddTypeContainer (TypeContainer tc)
 812                 {
 813                         var mn = tc.MemberName;
 814                         var name = mn.Basename;
 815                         while (mn.Left != null) {
 816                                 mn = mn.Left;
 817                                 name = mn.Name;
 818                         }
 819
 820                         var names_container = Parent == null ? Module : (TypeContainer) this;
 821
 822                         MemberCore mc;
 823                         if (names_container.DefinedNames.TryGetValue (name, out mc)) {
 824                                 if (tc is NamespaceContainer && mc is NamespaceContainer) {
 825                                         AddTypeContainerMember (tc);
 826                                         return;
 827                                 }
 828
 829                                 Report.SymbolRelatedToPreviousError (mc);
 830                                 if ((mc.ModFlags & Modifiers.PARTIAL) != 0 && (tc is ClassOrStruct || tc is Interface)) {
 831                                         Error_MissingPartialModifier (tc);
 832                                 } else {
 833                                         Report.Error (101, tc.Location, "The namespace `{0}' already contains a definition for `{1}'",
 834                                                 GetSignatureForError (), mn.GetSignatureForError ());
 835                                 }
 836                         } else {
 837                                 names_container.DefinedNames.Add (name, tc);
 838
 839                                 var tdef = tc.PartialContainer;
 840                                 if (tdef != null) {
 841                                         //
 842                                         // Same name conflict in different namespace containers
 843                                         //
 844                                         var conflict = ns.GetAllTypes (name);
 845                                         if (conflict != null) {
 846                                                 foreach (var e in conflict) {
 847                                                         if (e.Arity == mn.Arity) {
 848                                                                 mc = (MemberCore) e.MemberDefinition;
 849                                                                 break;
 850                                                         }
 851                                                 }
 852                                         }
 853
 854                                         if (mc != null) {
 855                                                 Report.SymbolRelatedToPreviousError (mc);
 856                                                 Report.Error (101, tc.Location, "The namespace `{0}' already contains a definition for `{1}'",
 857                                                         GetSignatureForError (), mn.GetSignatureForError ());
 858                                         } else {
 859                                                 ns.AddType (Module, tdef.Definition);
 860                                         }
 861                                 }
 862                         }
 863
 864                         base.AddTypeContainer (tc);
 865                 }
 866
 867                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
 868                 {
 869                         throw new NotSupportedException ();
 870                 }
 871
 872                 public override void EmitContainer ()
 873                 {
 874                         VerifyClsCompliance ();
 875
 876                         base.EmitContainer ();
 877                 }
 878
 879                 public ExtensionMethodCandidates LookupExtensionMethod (IMemberContext invocationContext, string name, int arity, int position)
 880                 {
 881                         //
 882                         // Here we try to resume the search for extension method at the point
 883                         // where the last bunch of candidates was found. It's more tricky than
 884                         // it seems as we have to check both namespace containers and namespace
 885                         // in correct order.
 886                         //
 887                         // Consider:
 888                         //
 889                         // namespace A {
 890                         //      using N1;
 891                         //  namespace B.C.D {
 892                         //              <our first search found candidates in A.B.C.D
 893                         //  }
 894                         // }
 895                         //
 896                         // In the example above namespace A.B.C.D, A.B.C and A.B have to be
 897                         // checked before we hit A.N1 using
 898                         //
 899                         ExtensionMethodCandidates candidates;
 900                         var container = this;
 901                         do {
 902                                 candidates = container.LookupExtensionMethodCandidates (invocationContext, name, arity, ref position);
 903                                 if (candidates != null || container.MemberName == null)
 904                                         return candidates;
 905
 906                                 var container_ns = container.ns.Parent;
 907                                 var mn = container.MemberName.Left;
 908                                 int already_checked = position - 2;
 909                                 while (already_checked-- > 0) {
 910                                         mn = mn.Left;
 911                                         container_ns = container_ns.Parent;
 912                                 }
 913
 914                                 while (mn != null) {
 915                                         ++position;
 916
 917                                         var methods = container_ns.LookupExtensionMethod (invocationContext, name, arity);
 918                                         if (methods != null) {
 919                                                 return new ExtensionMethodCandidates (invocationContext, methods, container, position);
 920                                         }
 921
 922                                         mn = mn.Left;
 923                                         container_ns = container_ns.Parent;
 924                                 }
 925
 926                                 position = 0;
 927                                 container = container.Parent;
 928                         } while (container != null);
 929
 930                         return null;
 931                 }
 932
 933                 ExtensionMethodCandidates LookupExtensionMethodCandidates (IMemberContext invocationContext, string name, int arity, ref int position)
 934                 {
 935                         List<MethodSpec> candidates = null;
 936
 937                         if (position == 0) {
 938                                 ++position;
 939
 940                                 candidates = ns.LookupExtensionMethod (invocationContext, name, arity);
 941                                 if (candidates != null) {
 942                                         return new ExtensionMethodCandidates (invocationContext, candidates, this, position);
 943                                 }
 944                         }
 945
 946                         if (position == 1) {
 947                                 ++position;
 948
 949                                 foreach (Namespace n in namespace_using_table) {
 950                                         var a = n.LookupExtensionMethod (invocationContext, name, arity);
 951                                         if (a == null)
 952                                                 continue;
 953
 954                                         if (candidates == null)
 955                                                 candidates = a;
 956                                         else
 957                                                 candidates.AddRange (a);
 958                                 }
 959
 960                                 if (types_using_table != null) {
 961                                         foreach (var t in types_using_table) {
 962
 963                                                 var res = t.MemberCache.FindExtensionMethods (invocationContext, name, arity);
 964                                                 if (res == null)
 965                                                         continue;
 966
 967                                                 if (candidates == null)
 968                                                         candidates = res;
 969                                                 else
 970                                                         candidates.AddRange (res);
 971                                         }
 972                                 }
 973
 974                                 if (candidates != null)
 975                                         return new ExtensionMethodCandidates (invocationContext, candidates, this, position);
 976                         }
 977
 978                         return null;
 979                 }
 980
 981                 public override FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
 982                 {
 983                         //
 984                         // Only simple names (no dots) will be looked up with this function
 985                         //
 986                         FullNamedExpression resolved;
 987                         for (NamespaceContainer container = this; container != null; container = container.Parent) {
 988                                 resolved = container.Lookup (name, arity, mode, loc);
 989                                 if (resolved != null || container.MemberName == null)
 990                                         return resolved;
 991
 992                                 var container_ns = container.ns.Parent;
 993                                 var mn = container.MemberName.Left;
 994                                 while (mn != null) {
 995                                         resolved = container_ns.LookupTypeOrNamespace (this, name, arity, mode, loc);
 996                                         if (resolved != null)
 997                                                 return resolved;
 998
 999                                         mn = mn.Left;
1000                                         container_ns = container_ns.Parent;
1001                                 }
1002                         }
1003
1004                         return null;
1005                 }
1006
1007                 public override void GetCompletionStartingWith (string prefix, List<string> results)
1008                 {
1009                         if (Usings == null)
1010                                 return;
1011
1012                         foreach (var un in Usings) {
1013                                 if (un.Alias != null)
1014                                         continue;
1015
1016                                 var name = un.NamespaceExpression.Name;
1017                                 if (name.StartsWith (prefix))
1018                                         results.Add (name);
1019                         }
1020
1021
1022                         IEnumerable<string> all = Enumerable.Empty<string> ();
1023
1024                         foreach (Namespace using_ns in namespace_using_table) {
1025                                 if (prefix.StartsWith (using_ns.Name)) {
1026                                         int ld = prefix.LastIndexOf ('.');
1027                                         if (ld != -1) {
1028                                                 string rest = prefix.Substring (ld + 1);
1029
1030                                                 all = all.Concat (using_ns.CompletionGetTypesStartingWith (rest));
1031                                         }
1032                                 }
1033                                 all = all.Concat (using_ns.CompletionGetTypesStartingWith (prefix));
1034                         }
1035
1036                         results.AddRange (all);
1037
1038                         base.GetCompletionStartingWith (prefix, results);
1039                 }
1040
1041
1042                 //
1043                 // Looks-up a alias named @name in this and surrounding namespace declarations
1044                 //
1045                 public FullNamedExpression LookupExternAlias (string name)
1046                 {
1047                         if (aliases == null)
1048                                 return null;
1049
1050                         UsingAliasNamespace uan;
1051                         if (aliases.TryGetValue (name, out uan) && uan is UsingExternAlias)
1052                                 return uan.ResolvedExpression;
1053
1054                         return null;
1055                 }
1056
1057                 //
1058                 // Looks-up a alias named @name in this and surrounding namespace declarations
1059                 //
1060                 public override FullNamedExpression LookupNamespaceAlias (string name)
1061                 {
1062                         for (NamespaceContainer n = this; n != null; n = n.Parent) {
1063                                 if (n.aliases == null)
1064                                         continue;
1065
1066                                 UsingAliasNamespace uan;
1067                                 if (n.aliases.TryGetValue (name, out uan))
1068                                         return uan.ResolvedExpression;
1069                         }
1070
1071                         return null;
1072                 }
1073
1074                 FullNamedExpression Lookup (string name, int arity, LookupMode mode, Location loc)
1075                 {
1076                         //
1077                         // Check whether it's in the namespace.
1078                         //
1079                         FullNamedExpression fne = ns.LookupTypeOrNamespace (this, name, arity, mode, loc);
1080
1081                         //
1082                         // Check aliases.
1083                         //
1084                         if (aliases != null && arity == 0) {
1085                                 UsingAliasNamespace uan;
1086                                 if (aliases.TryGetValue (name, out uan)) {
1087                                         if (fne != null && mode != LookupMode.Probing) {
1088                                                 // TODO: Namespace has broken location
1089                                                 //Report.SymbolRelatedToPreviousError (fne.Location, null);
1090                                                 Compiler.Report.SymbolRelatedToPreviousError (uan.Location, null);
1091                                                 Compiler.Report.Error (576, loc,
1092                                                         "Namespace `{0}' contains a definition with same name as alias `{1}'",
1093                                                         GetSignatureForError (), name);
1094                                         }
1095
1096                                         return uan.ResolvedExpression;
1097                                 }
1098                         }
1099
1100                         if (fne != null)
1101                                 return fne;
1102
1103                         //
1104                         // Lookup can be called before the namespace is defined from different namespace using alias clause
1105                         //
1106                         if (namespace_using_table == null) {
1107                                 DoDefineNamespace ();
1108                         }
1109
1110                         //
1111                         // Check using entries.
1112                         //
1113                         FullNamedExpression match = null;
1114                         foreach (Namespace using_ns in namespace_using_table) {
1115                                 //
1116                                 // A using directive imports only types contained in the namespace, it
1117                                 // does not import any nested namespaces
1118                                 //
1119                                 var t = using_ns.LookupType (this, name, arity, mode, loc);
1120                                 if (t == null)
1121                                         continue;
1122
1123                                 fne = new TypeExpression (t, loc);
1124                                 if (match == null) {
1125                                         match = fne;
1126                                         continue;
1127                                 }
1128
1129                                 // Prefer types over namespaces
1130                                 var texpr_fne = fne as TypeExpr;
1131                                 var texpr_match = match as TypeExpr;
1132                                 if (texpr_fne != null && texpr_match == null) {
1133                                         match = fne;
1134                                         continue;
1135                                 } else if (texpr_fne == null) {
1136                                         continue;
1137                                 }
1138
1139                                 // It can be top level accessibility only
1140                                 var better = Namespace.IsImportedTypeOverride (Module, texpr_match.Type, texpr_fne.Type);
1141                                 if (better == null) {
1142                                         if (mode == LookupMode.Normal) {
1143                                                 Compiler.Report.SymbolRelatedToPreviousError (texpr_match.Type);
1144                                                 Compiler.Report.SymbolRelatedToPreviousError (texpr_fne.Type);
1145                                                 Compiler.Report.Error (104, loc, "`{0}' is an ambiguous reference between `{1}' and `{2}'",
1146                                                         name, texpr_match.GetSignatureForError (), texpr_fne.GetSignatureForError ());
1147                                         }
1148
1149                                         return match;
1150                                 }
1151
1152                                 if (better == texpr_fne.Type)
1153                                         match = texpr_fne;
1154                         }
1155
1156                         return match;
1157                 }
1158
1159                 public static Expression LookupStaticUsings (IMemberContext mc, string name, int arity, Location loc)
1160                 {
1161                         for (var m = mc.CurrentMemberDefinition; m != null; m = m.Parent) {
1162
1163                                 var nc = m as NamespaceContainer;
1164                                 if (nc == null)
1165                                         continue;
1166
1167                                 List<MemberSpec> candidates = null;
1168                                 if (nc.types_using_table != null) {
1169                                         foreach (var using_type in nc.types_using_table) {
1170                                                 var members = MemberCache.FindMembers (using_type, name, true);
1171                                                 if (members != null) {
1172                                                         foreach (var member in members) {
1173                                                                 if ((member.Kind & MemberKind.NestedMask) != 0) {
1174                                                                         // non-static nested type is included with using static
1175                                                                 } else {
1176                                                                         if ((member.Modifiers & Modifiers.STATIC) == 0)
1177                                                                                 continue;
1178
1179                                                                         if ((member.Modifiers & Modifiers.METHOD_EXTENSION) != 0)
1180                                                                                 continue;
1181                                                                 }
1182
1183                                                                 if (arity > 0 && member.Arity != arity)
1184                                                                         continue;
1185
1186                                                                 if (candidates == null)
1187                                                                         candidates = new List<MemberSpec> ();
1188
1189                                                                 candidates.Add (member);
1190                                                         }
1191                                                 }
1192                                         }
1193                                 }
1194
1195                                 if (candidates != null) {
1196                                         var expr = Expression.MemberLookupToExpression (mc, candidates, false, null, name, arity, Expression.MemberLookupRestrictions.None, loc);
1197                                         if (expr != null)
1198                                                 return expr;
1199                                 }
1200                         }
1201
1202                         return null;
1203                 }
1204
1205                 protected override void DefineNamespace ()
1206                 {
1207                         if (namespace_using_table == null)
1208                                 DoDefineNamespace ();
1209
1210                         base.DefineNamespace ();
1211                 }
1212
1213                 void DoDefineNamespace ()
1214                 {
1215                         namespace_using_table = empty_namespaces;
1216
1217                         if (clauses != null) {
1218                                 List<Namespace> namespaces = null;
1219                                 List<TypeSpec> types = null;
1220
1221                                 bool post_process_using_aliases = false;
1222
1223                                 for (int i = 0; i < clauses.Count; ++i) {
1224                                         var entry = clauses[i];
1225
1226                                         if (entry.Alias != null) {
1227                                                 if (aliases == null)
1228                                                         aliases = new Dictionary<string, UsingAliasNamespace> ();
1229
1230                                                 //
1231                                                 // Aliases are not available when resolving using section
1232                                                 // except extern aliases
1233                                                 //
1234                                                 if (entry is UsingExternAlias) {
1235                                                         entry.Define (this);
1236                                                         if (entry.ResolvedExpression != null)
1237                                                                 aliases.Add (entry.Alias.Value, (UsingExternAlias) entry);
1238
1239                                                         clauses.RemoveAt (i--);
1240                                                 } else {
1241                                                         post_process_using_aliases = true;
1242                                                 }
1243
1244                                                 continue;
1245                                         }
1246
1247                                         entry.Define (this);
1248
1249                                         //
1250                                         // It's needed for repl only, when using clause cannot be resolved don't hold it in
1251                                         // global list which is resolved for each evaluation
1252                                         //
1253                                         if (entry.ResolvedExpression == null) {
1254                                                 clauses.RemoveAt (i--);
1255                                                 continue;
1256                                         }
1257
1258                                         var using_ns = entry.ResolvedExpression as NamespaceExpression;
1259                                         if (using_ns == null) {
1260
1261                                                 var type = entry.ResolvedExpression.Type;
1262
1263                                                 if (types == null)
1264                                                         types = new List<TypeSpec> ();
1265
1266                                                 if (types.Contains (type)) {
1267                                                         Warning_DuplicateEntry (entry);
1268                                                 } else {
1269                                                         types.Add (type);
1270                                                 }
1271                                         } else {
1272                                                 if (namespaces == null)
1273                                                         namespaces = new List<Namespace> ();
1274
1275                                                 if (namespaces.Contains (using_ns.Namespace)) {
1276                                                         // Ensure we don't report the warning multiple times in repl
1277                                                         clauses.RemoveAt (i--);
1278
1279                                                         Warning_DuplicateEntry (entry);
1280                                                 } else {
1281                                                         namespaces.Add (using_ns.Namespace);
1282                                                 }
1283                                         }
1284                                 }
1285
1286                                 namespace_using_table = namespaces == null ? new Namespace [0] : namespaces.ToArray ();
1287                                 if (types != null)
1288                                         types_using_table = types.ToArray ();
1289
1290                                 if (post_process_using_aliases) {
1291                                         for (int i = 0; i < clauses.Count; ++i) {
1292                                                 var entry = clauses[i];
1293                                                 if (entry.Alias != null) {
1294                                                         entry.Define (this);
1295                                                         if (entry.ResolvedExpression != null) {
1296                                                                 aliases.Add (entry.Alias.Value, (UsingAliasNamespace) entry);
1297                                                         }
1298
1299                                                         clauses.RemoveAt (i--);
1300                                                 }
1301                                         }
1302                                 }
1303                         }
1304                 }
1305
1306                 public void EnableRedefinition ()
1307                 {
1308                         is_defined = false;
1309                         namespace_using_table = null;
1310                 }
1311
1312                 internal override void GenerateDocComment (DocumentationBuilder builder)
1313                 {
1314                         if (containers != null) {
1315                                 foreach (var tc in containers)
1316                                         tc.GenerateDocComment (builder);
1317                         }
1318                 }
1319
1320                 public override string GetSignatureForError ()
1321                 {
1322                         return MemberName == null ? "global::" : base.GetSignatureForError ();
1323                 }
1324
1325                 public override void RemoveContainer (TypeContainer cont)
1326                 {
1327                         base.RemoveContainer (cont);
1328                         NS.RemoveContainer (cont);
1329                 }
1330
1331                 protected override bool VerifyClsCompliance ()
1332                 {
1333                         if (Module.IsClsComplianceRequired ()) {
1334                                 if (MemberName != null && MemberName.Name[0] == '_') {
1335                                         Warning_IdentifierNotCompliant ();
1336                                 }
1337
1338                                 ns.VerifyClsCompliance ();
1339                                 return true;
1340                         }
1341
1342                         return false;
1343                 }
1344
1345                 void Warning_DuplicateEntry (UsingClause entry)
1346                 {
1347                         Compiler.Report.Warning (105, 3, entry.Location,
1348                                 "The using directive for `{0}' appeared previously in this namespace",
1349                                 entry.ResolvedExpression.GetSignatureForError ());
1350                 }
1351
1352                 public override void Accept (StructuralVisitor visitor)
1353                 {
1354                         visitor.Visit (this);
1355                 }
1356         }
1357
1358         public class UsingNamespace : UsingClause
1359         {
1360                 public UsingNamespace (ATypeNameExpression expr, Location loc)
1361                         : base (expr, loc)
1362                 {
1363                 }
1364
1365                 public override void Define (NamespaceContainer ctx)
1366                 {
1367                         base.Define (ctx);
1368
1369                         var ns = resolved as NamespaceExpression;
1370                         if (ns != null)
1371                                 return;
1372
1373                         if (resolved != null) {
1374                                 var compiler = ctx.Module.Compiler;
1375                                 var type = resolved.Type;
1376
1377                                 compiler.Report.SymbolRelatedToPreviousError (type);
1378                                 compiler.Report.Error (138, Location,
1379                                         "A `using' directive can only be applied to namespaces but `{0}' denotes a type. Consider using a `using static' instead",
1380                                         type.GetSignatureForError ());
1381                         }
1382                 }
1383         }
1384
1385         public class UsingType : UsingClause
1386         {
1387                 public UsingType (ATypeNameExpression expr, Location loc)
1388                         : base (expr, loc)
1389                 {
1390                 }
1391
1392                 public override void Define (NamespaceContainer ctx)
1393                 {
1394                         base.Define (ctx);
1395
1396                         if (resolved == null)
1397                                 return;
1398
1399                         var ns = resolved as NamespaceExpression;
1400                         if (ns != null) {
1401                                 var compiler = ctx.Module.Compiler;
1402                                 compiler.Report.Error (7007, Location,
1403                                         "A 'using static' directive can only be applied to types but `{0}' denotes a namespace. Consider using a `using' directive instead",
1404                                         ns.GetSignatureForError ());
1405                                 return;
1406                         }
1407
1408                         // TODO: Need to move it to post_process_using_aliases
1409                         //ObsoleteAttribute obsolete_attr = resolved.Type.GetAttributeObsolete ();
1410                         //if (obsolete_attr != null) {
1411                         //      AttributeTester.Report_ObsoleteMessage (obsolete_attr, resolved.GetSignatureForError (), Location, ctx.Compiler.Report);
1412                         //}
1413                 }
1414         }
1415
1416         public class UsingClause
1417         {
1418                 readonly ATypeNameExpression expr;
1419                 readonly Location loc;
1420                 protected FullNamedExpression resolved;
1421
1422                 public UsingClause (ATypeNameExpression expr, Location loc)
1423                 {
1424                         this.expr = expr;
1425                         this.loc = loc;
1426                 }
1427
1428                 #region Properties
1429
1430                 public virtual SimpleMemberName Alias {
1431                         get {
1432                                 return null;
1433                         }
1434                 }
1435
1436                 public Location Location {
1437                         get {
1438                                 return loc;
1439                         }
1440                 }
1441
1442                 public ATypeNameExpression NamespaceExpression  {
1443                         get {
1444                                 return expr;
1445                         }
1446                 }
1447
1448                 public FullNamedExpression ResolvedExpression {
1449                         get {
1450                                 return resolved;
1451                         }
1452                 }
1453
1454                 #endregion
1455
1456                 public string GetSignatureForError ()
1457                 {
1458                         return expr.GetSignatureForError ();
1459                 }
1460
1461                 public virtual void Define (NamespaceContainer ctx)
1462                 {
1463                         resolved = expr.ResolveAsTypeOrNamespace (ctx, false);
1464                 }
1465
1466                 public override string ToString()
1467                 {
1468                         return resolved.ToString();
1469                 }
1470         }
1471
1472         public class UsingExternAlias : UsingAliasNamespace
1473         {
1474                 public UsingExternAlias (SimpleMemberName alias, Location loc)
1475                         : base (alias, null, loc)
1476                 {
1477                 }
1478
1479                 public override void Define (NamespaceContainer ctx)
1480                 {
1481                         var ns = ctx.Module.GetRootNamespace (Alias.Value);
1482                         if (ns == null) {
1483                                 ctx.Module.Compiler.Report.Error (430, Location,
1484                                         "The extern alias `{0}' was not specified in -reference option",
1485                                         Alias.Value);
1486                                 return;
1487                         }
1488
1489                         resolved = new NamespaceExpression (ns, Location);
1490                 }
1491         }
1492
1493         public class UsingAliasNamespace : UsingNamespace
1494         {
1495                 readonly SimpleMemberName alias;
1496
1497                 public struct AliasContext : IMemberContext
1498                 {
1499                         readonly NamespaceContainer ns;
1500
1501                         public AliasContext (NamespaceContainer ns)
1502                         {
1503                                 this.ns = ns;
1504                         }
1505
1506                         public TypeSpec CurrentType {
1507                                 get {
1508                                         return null;
1509                                 }
1510                         }
1511
1512                         public TypeParameters CurrentTypeParameters {
1513                                 get {
1514                                         return null;
1515                                 }
1516                         }
1517
1518                         public MemberCore CurrentMemberDefinition {
1519                                 get {
1520                                         return null;
1521                                 }
1522                         }
1523
1524                         public bool IsObsolete {
1525                                 get {
1526                                         return false;
1527                                 }
1528                         }
1529
1530                         public bool IsUnsafe {
1531                                 get {
1532                                         throw new NotImplementedException ();
1533                                 }
1534                         }
1535
1536                         public bool IsStatic {
1537                                 get {
1538                                         throw new NotImplementedException ();
1539                                 }
1540                         }
1541
1542                         public ModuleContainer Module {
1543                                 get {
1544                                         return ns.Module;
1545                                 }
1546                         }
1547
1548                         public string GetSignatureForError ()
1549                         {
1550                                 throw new NotImplementedException ();
1551                         }
1552
1553                         public ExtensionMethodCandidates LookupExtensionMethod (string name, int arity)
1554                         {
1555                                 return null;
1556                         }
1557
1558                         public FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
1559                         {
1560                                 var fne = ns.NS.LookupTypeOrNamespace (ns, name, arity, mode, loc);
1561                                 if (fne != null)
1562                                         return fne;
1563
1564                                 //
1565                                 // Only extern aliases are allowed in this context
1566                                 //
1567                                 fne = ns.LookupExternAlias (name);
1568                                 if (fne != null || ns.MemberName == null)
1569                                         return fne;
1570
1571                                 var container_ns = ns.NS.Parent;
1572                                 var mn = ns.MemberName.Left;
1573                                 while (mn != null) {
1574                                         fne = container_ns.LookupTypeOrNamespace (this, name, arity, mode, loc);
1575                                         if (fne != null)
1576                                                 return fne;
1577
1578                                         mn = mn.Left;
1579                                         container_ns = container_ns.Parent;
1580                                 }
1581
1582                                 if (ns.Parent != null)
1583                                         return ns.Parent.LookupNamespaceOrType (name, arity, mode, loc);
1584
1585                                 return null;
1586                         }
1587
1588                         public FullNamedExpression LookupNamespaceAlias (string name)
1589                         {
1590                                 return ns.LookupNamespaceAlias (name);
1591                         }
1592                 }
1593
1594                 public UsingAliasNamespace (SimpleMemberName alias, ATypeNameExpression expr, Location loc)
1595                         : base (expr, loc)
1596                 {
1597                         this.alias = alias;
1598                 }
1599
1600                 public override SimpleMemberName Alias {
1601                         get {
1602                                 return alias;
1603                         }
1604                 }
1605
1606                 public override void Define (NamespaceContainer ctx)
1607                 {
1608                         //
1609                         // The namespace-or-type-name of a using-alias-directive is resolved as if
1610                         // the immediately containing compilation unit or namespace body had no
1611                         // using-directives. A using-alias-directive may however be affected
1612                         // by extern-alias-directives in the immediately containing compilation
1613                         // unit or namespace body
1614                         //
1615                         // We achieve that by introducing alias-context which redirect any local
1616                         // namespace or type resolve calls to parent namespace
1617                         //
1618                         resolved = NamespaceExpression.ResolveAsTypeOrNamespace (new AliasContext (ctx), false);
1619                 }
1620         }
1621 }