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