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.Name";
 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                         Namespace ns_parent;
 280                         if (name.Left != null) {
 281                                 if (parent != null)
 282                                         ns_parent = parent.AddNamespace (name.Left);
 283                                 else
 284                                         ns_parent = AddNamespace (name.Left);
 285                         } else {
 286                                 ns_parent = this;
 287                         }
 288
 289                         return ns_parent.TryAddNamespace (name.Basename);
 290                 }
 291
 292                 Namespace TryAddNamespace (string name)
 293                 {
 294                         Namespace ns;
 295
 296                         if (!namespaces.TryGetValue (name, out ns)) {
 297                                 ns = new Namespace (this, name);
 298                                 namespaces.Add (name, ns);
 299                         }
 300
 301                         return ns;
 302                 }
 303
 304                 // TODO: Replace with CreateNamespace where MemberName is created for the method call
 305                 public Namespace GetNamespace (string name, bool create)
 306                 {
 307                         int pos = name.IndexOf ('.');
 308
 309                         Namespace ns;
 310                         string first;
 311                         if (pos >= 0)
 312                                 first = name.Substring (0, pos);
 313                         else
 314                                 first = name;
 315
 316                         if (!namespaces.TryGetValue (first, out ns)) {
 317                                 if (!create)
 318                                         return null;
 319
 320                                 ns = new Namespace (this, first);
 321                                 namespaces.Add (first, ns);
 322                         }
 323
 324                         if (pos >= 0)
 325                                 ns = ns.GetNamespace (name.Substring (pos + 1), create);
 326
 327                         return ns;
 328                 }
 329
 330                 public IList<TypeSpec> GetAllTypes (string name)
 331                 {
 332                         IList<TypeSpec> found;
 333                         if (types == null || !types.TryGetValue (name, out found))
 334                                 return null;
 335
 336                         return found;
 337                 }
 338
 339                 public TypeExpr LookupType (IMemberContext ctx, string name, int arity, LookupMode mode, Location loc)
 340                 {
 341                         if (types == null)
 342                                 return null;
 343
 344                         TypeExpr te;
 345                         if (arity == 0 && cached_types.TryGetValue (name, out te))
 346                                 return te;
 347
 348                         IList<TypeSpec> found;
 349                         if (!types.TryGetValue (name, out found))
 350                                 return null;
 351
 352                         TypeSpec best = null;
 353                         foreach (var ts in found) {
 354                                 if (ts.Arity == arity) {
 355                                         if (best == null) {
 356                                                 if ((ts.Modifiers & Modifiers.INTERNAL) != 0 && !ts.MemberDefinition.IsInternalAsPublic (ctx.Module.DeclaringAssembly) && mode != LookupMode.IgnoreAccessibility)
 357                                                         continue;
 358
 359                                                 best = ts;
 360                                                 continue;
 361                                         }
 362
 363                                         if (best.MemberDefinition.IsImported && ts.MemberDefinition.IsImported) {
 364                                                 if (mode == LookupMode.Normal) {
 365                                                         ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (best);
 366                                                         ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
 367                                                         ctx.Module.Compiler.Report.Error (433, loc, "The imported type `{0}' is defined multiple times", ts.GetSignatureForError ());
 368                                                 }
 369                                                 break;
 370                                         }
 371
 372                                         if (best.MemberDefinition.IsImported)
 373                                                 best = ts;
 374
 375                                         if ((best.Modifiers & Modifiers.INTERNAL) != 0 && !best.MemberDefinition.IsInternalAsPublic (ctx.Module.DeclaringAssembly))
 376                                                 continue;
 377
 378                                         if (mode != LookupMode.Normal)
 379                                                 continue;
 380
 381                                         if (ts.MemberDefinition.IsImported)
 382                                                 ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ts);
 383
 384                                         ctx.Module.Compiler.Report.Warning (436, 2, loc,
 385                                                 "The type `{0}' conflicts with the imported type of same name'. Ignoring the imported type definition",
 386                                                 best.GetSignatureForError ());
 387                                 }
 388
 389                                 //
 390                                 // Lookup for the best candidate with the closest arity match
 391                                 //
 392                                 if (arity < 0) {
 393                                         if (best == null) {
 394                                                 best = ts;
 395                                         } else if (System.Math.Abs (ts.Arity + arity) < System.Math.Abs (best.Arity + arity)) {
 396                                                 best = ts;
 397                                         }
 398                                 }
 399                         }
 400
 401                         if (best == null)
 402                                 return null;
 403
 404                         te = new TypeExpression (best, Location.Null);
 405
 406                         // TODO MemberCache: Cache more
 407                         if (arity == 0 && mode == LookupMode.Normal)
 408                                 cached_types.Add (name, te);
 409
 410                         return te;
 411                 }
 412
 413                 public FullNamedExpression LookupTypeOrNamespace (IMemberContext ctx, string name, int arity, LookupMode mode, Location loc)
 414                 {
 415                         var texpr = LookupType (ctx, name, arity, mode, loc);
 416
 417                         Namespace ns;
 418                         if (arity == 0 && namespaces.TryGetValue (name, out ns)) {
 419                                 if (texpr == null)
 420                                         return ns;
 421
 422                                 if (mode != LookupMode.Probing) {
 423                                         ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (texpr.Type);
 424                                         // ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (ns.loc, "");
 425                                         ctx.Module.Compiler.Report.Warning (437, 2, loc,
 426                                                 "The type `{0}' conflicts with the imported namespace `{1}'. Using the definition found in the source file",
 427                                                 texpr.GetSignatureForError (), ns.GetSignatureForError ());
 428                                 }
 429
 430                                 if (texpr.Type.MemberDefinition.IsImported)
 431                                         return ns;
 432                         }
 433
 434                         return texpr;
 435                 }
 436
 437                 //
 438                 // Completes types with the given `prefix'
 439                 //
 440                 public IEnumerable<string> CompletionGetTypesStartingWith (string prefix)
 441                 {
 442                         if (types == null)
 443                                 return Enumerable.Empty<string> ();
 444
 445                         var res = from item in types
 446                                           where item.Key.StartsWith (prefix) && item.Value.Any (l => (l.Modifiers & Modifiers.PUBLIC) != 0)
 447                                           select item.Key;
 448
 449                         if (namespaces != null)
 450                                 res = res.Concat (from item in namespaces where item.Key.StartsWith (prefix) select item.Key);
 451
 452                         return res;
 453                 }
 454
 455                 //
 456                 // Looks for extension method in this namespace
 457                 //
 458                 public List<MethodSpec> LookupExtensionMethod (IMemberContext invocationContext, TypeSpec extensionType, string name, int arity)
 459                 {
 460                         if (extension_method_types == null)
 461                                 return null;
 462
 463                         List<MethodSpec> found = null;
 464                         for (int i = 0; i < extension_method_types.Count; ++i) {
 465                                 var ts = extension_method_types[i];
 466
 467                                 //
 468                                 // When the list was built we didn't know what members the type
 469                                 // contains
 470                                 //
 471                                 if ((ts.Modifiers & Modifiers.METHOD_EXTENSION) == 0) {
 472                                         if (extension_method_types.Count == 1) {
 473                                                 extension_method_types = null;
 474                                                 return found;
 475                                         }
 476
 477                                         extension_method_types.RemoveAt (i--);
 478                                         continue;
 479                                 }
 480
 481                                 var res = ts.MemberCache.FindExtensionMethods (invocationContext, extensionType, name, arity);
 482                                 if (res == null)
 483                                         continue;
 484
 485                                 if (found == null) {
 486                                         found = res;
 487                                 } else {
 488                                         found.AddRange (res);
 489                                 }
 490                         }
 491
 492                         return found;
 493                 }
 494
 495                 public void AddType (ModuleContainer module, TypeSpec ts)
 496                 {
 497                         if (types == null) {
 498                                 types = new Dictionary<string, IList<TypeSpec>> (64);
 499                         }
 500
 501                         if ((ts.IsStatic || ts.MemberDefinition.IsPartial) && ts.Arity == 0 &&
 502                                 (ts.MemberDefinition.DeclaringAssembly == null || ts.MemberDefinition.DeclaringAssembly.HasExtensionMethod)) {
 503                                 if (extension_method_types == null)
 504                                         extension_method_types = new List<TypeSpec> ();
 505
 506                                 extension_method_types.Add (ts);
 507                         }
 508
 509                         var name = ts.Name;
 510                         IList<TypeSpec> existing;
 511                         if (types.TryGetValue (name, out existing)) {
 512                                 TypeSpec better_type;
 513                                 TypeSpec found;
 514                                 if (existing.Count == 1) {
 515                                         found = existing[0];
 516                                         if (ts.Arity == found.Arity) {
 517                                                 better_type = IsImportedTypeOverride (module, ts, found);
 518                                                 if (better_type == found)
 519                                                         return;
 520
 521                                                 if (better_type != null) {
 522                                                         existing [0] = better_type;
 523                                                         return;
 524                                                 }
 525                                         }
 526
 527                                         existing = new List<TypeSpec> ();
 528                                         existing.Add (found);
 529                                         types[name] = existing;
 530                                 } else {
 531                                         for (int i = 0; i < existing.Count; ++i) {
 532                                                 found = existing[i];
 533                                                 if (ts.Arity != found.Arity)
 534                                                         continue;
 535
 536                                                 better_type = IsImportedTypeOverride (module, ts, found);
 537                                                 if (better_type == found)
 538                                                         return;
 539
 540                                                 if (better_type != null) {
 541                                                         existing.RemoveAt (i);
 542                                                         --i;
 543                                                         continue;
 544                                                 }
 545                                         }
 546                                 }
 547
 548                                 existing.Add (ts);
 549                         } else {
 550                                 types.Add (name, new TypeSpec[] { ts });
 551                         }
 552                 }
 553
 554                 //
 555                 // We import any types but in the situation there are same types
 556                 // but one has better visibility (either public or internal with friend)
 557                 // the less visible type is removed from the namespace cache
 558                 //
 559                 public static TypeSpec IsImportedTypeOverride (ModuleContainer module, TypeSpec ts, TypeSpec found)
 560                 {
 561                         var ts_accessible = (ts.Modifiers & Modifiers.PUBLIC) != 0 || ts.MemberDefinition.IsInternalAsPublic (module.DeclaringAssembly);
 562                         var found_accessible = (found.Modifiers & Modifiers.PUBLIC) != 0 || found.MemberDefinition.IsInternalAsPublic (module.DeclaringAssembly);
 563
 564                         if (ts_accessible && !found_accessible)
 565                                 return ts;
 566
 567                         // found is better always better for accessible or inaccessible ts
 568                         if (!ts_accessible)
 569                                 return found;
 570
 571                         return null;
 572                 }
 573
 574                 public void RemoveContainer (TypeContainer tc)
 575                 {
 576                         types.Remove (tc.Basename);
 577                         cached_types.Remove (tc.Basename);
 578                 }
 579
 580                 public override FullNamedExpression ResolveAsTypeOrNamespace (IMemberContext mc)
 581                 {
 582                         return this;
 583                 }
 584
 585                 public void SetBuiltinType (BuiltinTypeSpec pts)
 586                 {
 587                         var found = types[pts.Name];
 588                         cached_types.Remove (pts.Name);
 589                         if (found.Count == 1) {
 590                                 types[pts.Name][0] = pts;
 591                         } else {
 592                                 throw new NotImplementedException ();
 593                         }
 594                 }
 595
 596                 public void VerifyClsCompliance ()
 597                 {
 598                         if (types == null || cls_checked)
 599                                 return;
 600
 601                         cls_checked = true;
 602
 603                         // TODO: This is quite ugly way to check for CLS compliance at namespace level
 604
 605                         var locase_types = new Dictionary<string, List<TypeSpec>> (StringComparer.OrdinalIgnoreCase);
 606                         foreach (var tgroup in types.Values) {
 607                                 foreach (var tm in tgroup) {
 608                                         if ((tm.Modifiers & Modifiers.PUBLIC) == 0 || !tm.IsCLSCompliant ())
 609                                                 continue;
 610
 611                                         List<TypeSpec> found;
 612                                         if (!locase_types.TryGetValue (tm.Name, out found)) {
 613                                                 found = new List<TypeSpec> ();
 614                                                 locase_types.Add (tm.Name, found);
 615                                         }
 616
 617                                         found.Add (tm);
 618                                 }
 619                         }
 620
 621                         foreach (var locase in locase_types.Values) {
 622                                 if (locase.Count < 2)
 623                                         continue;
 624
 625                                 bool all_same = true;
 626                                 foreach (var notcompliant in locase) {
 627                                         all_same = notcompliant.Name == locase[0].Name;
 628                                         if (!all_same)
 629                                                 break;
 630                                 }
 631
 632                                 if (all_same)
 633                                         continue;
 634
 635                                 TypeContainer compiled = null;
 636                                 foreach (var notcompliant in locase) {
 637                                         if (!notcompliant.MemberDefinition.IsImported) {
 638                                                 if (compiled != null)
 639                                                         compiled.Compiler.Report.SymbolRelatedToPreviousError (compiled);
 640
 641                                                 compiled = notcompliant.MemberDefinition as TypeContainer;
 642                                         } else {
 643                                                 compiled.Compiler.Report.SymbolRelatedToPreviousError (notcompliant);
 644                                         }
 645                                 }
 646
 647                                 compiled.Compiler.Report.Warning (3005, 1, compiled.Location,
 648                                         "Identifier `{0}' differing only in case is not CLS-compliant", compiled.GetSignatureForError ());
 649                         }
 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
 759
 760         //
 761         // Namespace block as created by the parser
 762         //
 763         public class NamespaceContainer : TypeContainer, IMemberContext
 764         {
 765                 static readonly Namespace[] empty_namespaces = new Namespace[0];
 766
 767                 readonly Namespace ns;
 768
 769                 public new readonly NamespaceContainer Parent;
 770
 771                 List<UsingNamespace> clauses;
 772
 773                 // Used by parsed to check for parser errors
 774                 public bool DeclarationFound;
 775
 776                 Namespace[] namespace_using_table;
 777                 Dictionary<string, UsingAliasNamespace> aliases;
 778
 779                 public NamespaceContainer (MemberName name, NamespaceContainer parent)
 780                         : base (parent, name, null, MemberKind.Namespace)
 781                 {
 782                         this.Parent = parent;
 783                         this.ns = parent.NS.AddNamespace (name);
 784
 785                         containers = new List<TypeContainer> ();
 786                 }
 787
 788                 protected NamespaceContainer (ModuleContainer parent)
 789                         : base (parent, null, null, MemberKind.Namespace)
 790                 {
 791                         ns = parent.GlobalRootNamespace;
 792                         containers = new List<TypeContainer> (2);
 793                 }
 794
 795                 #region Properties
 796
 797                 public override AttributeTargets AttributeTargets {
 798                         get {
 799                                 throw new NotSupportedException ();
 800                         }
 801                 }
 802
 803                 public override string DocCommentHeader {
 804                         get {
 805                                 throw new NotSupportedException ();
 806                         }
 807                 }
 808
 809                 public Namespace NS {
 810                         get {
 811                                 return ns;
 812                         }
 813                 }
 814
 815                 public List<UsingNamespace> Usings {
 816                         get {
 817                                 return clauses;
 818                         }
 819                 }
 820
 821                 public override string[] ValidAttributeTargets {
 822                         get {
 823                                 throw new NotSupportedException ();
 824                         }
 825                 }
 826
 827                 #endregion
 828
 829                 public void AddUsing (UsingNamespace un)
 830                 {
 831                         if (DeclarationFound){
 832                                 Compiler.Report.Error (1529, un.Location, "A using clause must precede all other namespace elements except extern alias declarations");
 833                         }
 834
 835                         if (clauses == null)
 836                                 clauses = new List<UsingNamespace> ();
 837
 838                         clauses.Add (un);
 839                 }
 840
 841                 public void AddUsing (UsingAliasNamespace un)
 842                 {
 843                         if (DeclarationFound){
 844                                 Compiler.Report.Error (1529, un.Location, "A using clause must precede all other namespace elements except extern alias declarations");
 845                         }
 846
 847                         AddAlias (un);
 848                 }
 849
 850                 void AddAlias (UsingAliasNamespace un)
 851                 {
 852                         if (clauses == null) {
 853                                 clauses = new List<UsingNamespace> ();
 854                         } else {
 855                                 foreach (var entry in clauses) {
 856                                         var a = entry as UsingAliasNamespace;
 857                                         if (a != null && a.Alias.Value == un.Alias.Value) {
 858                                                 Compiler.Report.SymbolRelatedToPreviousError (a.Location, "");
 859                                                 Compiler.Report.Error (1537, un.Location,
 860                                                         "The using alias `{0}' appeared previously in this namespace", un.Alias.Value);
 861                                         }
 862                                 }
 863                         }
 864
 865                         clauses.Add (un);
 866                 }
 867
 868                 public override void AddPartial (TypeDefinition next_part)
 869                 {
 870                         var existing = ns.LookupType (this, next_part.MemberName.Name, next_part.MemberName.Arity, LookupMode.Probing, Location.Null);
 871                         var td = existing != null ? existing.Type.MemberDefinition as TypeDefinition : null;
 872                         AddPartial (next_part, td);
 873                 }
 874
 875                 public override void AddTypeContainer (TypeContainer tc)
 876                 {
 877                         string name = tc.Basename;
 878
 879                         var mn = tc.MemberName;
 880                         while (mn.Left != null) {
 881                                 mn = mn.Left;
 882                                 name = mn.Name;
 883                         }
 884
 885                         var names_container = Parent == null ? Module : (TypeContainer) this;
 886
 887                         MemberCore mc;
 888                         if (names_container.DefinedNames.TryGetValue (name, out mc)) {
 889                                 if (tc is NamespaceContainer && mc is NamespaceContainer) {
 890                                         containers.Add (tc);
 891                                         return;
 892                                 }
 893
 894                                 Report.SymbolRelatedToPreviousError (mc);
 895                                 if ((mc.ModFlags & Modifiers.PARTIAL) != 0 && (tc is ClassOrStruct || tc is Interface)) {
 896                                         Error_MissingPartialModifier (tc);
 897                                 } else {
 898                                         Report.Error (101, tc.Location, "The namespace `{0}' already contains a definition for `{1}'",
 899                                                 GetSignatureForError (), mn.GetSignatureForError ());
 900                                 }
 901                         } else {
 902                                 names_container.DefinedNames.Add (name, tc);
 903
 904                                 var tdef = tc.PartialContainer;
 905                                 if (tdef != null) {
 906                                         //
 907                                         // Same name conflict in different namespace containers
 908                                         //
 909                                         var conflict = ns.GetAllTypes (name);
 910                                         if (conflict != null) {
 911                                                 foreach (var e in conflict) {
 912                                                         if (e.Arity == mn.Arity) {
 913                                                                 mc = (MemberCore) e.MemberDefinition;
 914                                                                 break;
 915                                                         }
 916                                                 }
 917                                         }
 918
 919                                         if (mc != null) {
 920                                                 Report.SymbolRelatedToPreviousError (mc);
 921                                                 Report.Error (101, tc.Location, "The namespace `{0}' already contains a definition for `{1}'",
 922                                                         GetSignatureForError (), mn.GetSignatureForError ());
 923                                         } else {
 924                                                 ns.AddType (Module, tdef.Definition);
 925                                         }
 926                                 }
 927                         }
 928
 929                         base.AddTypeContainer (tc);
 930                 }
 931
 932                 public override void ApplyAttributeBuilder (Attribute a, MethodSpec ctor, byte[] cdata, PredefinedAttributes pa)
 933                 {
 934                         throw new NotSupportedException ();
 935                 }
 936
 937                 public override void EmitContainer ()
 938                 {
 939                         VerifyClsCompliance ();
 940
 941                         base.EmitContainer ();
 942                 }
 943
 944                 public ExtensionMethodCandidates LookupExtensionMethod (IMemberContext invocationContext, TypeSpec extensionType, string name, int arity, int position)
 945                 {
 946                         //
 947                         // Here we try to resume the search for extension method at the point
 948                         // where the last bunch of candidates was found. It's more tricky than
 949                         // it seems as we have to check both namespace containers and namespace
 950                         // in correct order.
 951                         //
 952                         // Consider:
 953                         //
 954                         // namespace A {
 955                         //      using N1;
 956                         //  namespace B.C.D {
 957                         //              <our first search found candidates in A.B.C.D
 958                         //  }
 959                         // }
 960                         //
 961                         // In the example above namespace A.B.C.D, A.B.C and A.B have to be
 962                         // checked before we hit A.N1 using
 963                         //
 964                         ExtensionMethodCandidates candidates;
 965                         var container = this;
 966                         do {
 967                                 candidates = container.LookupExtensionMethodCandidates (invocationContext, extensionType, name, arity, ref position);
 968                                 if (candidates != null || container.MemberName == null)
 969                                         return candidates;
 970
 971                                 var container_ns = container.ns.Parent;
 972                                 var mn = container.MemberName.Left;
 973                                 int already_checked = position - 2;
 974                                 while (already_checked-- > 0) {
 975                                         mn = mn.Left;
 976                                         container_ns = container_ns.Parent;
 977                                 }
 978
 979                                 while (mn != null) {
 980                                         ++position;
 981
 982                                         var methods = container_ns.LookupExtensionMethod (invocationContext, extensionType, name, arity);
 983                                         if (methods != null) {
 984                                                 return new ExtensionMethodCandidates (invocationContext, methods, container, position);
 985                                         }
 986
 987                                         mn = mn.Left;
 988                                         container_ns = container_ns.Parent;
 989                                 }
 990
 991                                 position = 0;
 992                                 container = container.Parent;
 993                         } while (container != null);
 994
 995                         return null;
 996                 }
 997
 998                 ExtensionMethodCandidates LookupExtensionMethodCandidates (IMemberContext invocationContext, TypeSpec extensionType, string name, int arity, ref int position)
 999                 {
1000                         List<MethodSpec> candidates = null;
1001
1002                         if (position == 0) {
1003                                 ++position;
1004
1005                                 candidates = ns.LookupExtensionMethod (invocationContext, extensionType, name, arity);
1006                                 if (candidates != null) {
1007                                         return new ExtensionMethodCandidates (invocationContext, candidates, this, position);
1008                                 }
1009                         }
1010
1011                         if (position == 1) {
1012                                 ++position;
1013
1014                                 foreach (Namespace n in namespace_using_table) {
1015                                         var a = n.LookupExtensionMethod (invocationContext, extensionType, name, arity);
1016                                         if (a == null)
1017                                                 continue;
1018
1019                                         if (candidates == null)
1020                                                 candidates = a;
1021                                         else
1022                                                 candidates.AddRange (a);
1023                                 }
1024
1025                                 if (candidates != null)
1026                                         return new ExtensionMethodCandidates (invocationContext, candidates, this, position);
1027                         }
1028
1029                         return null;
1030                 }
1031
1032                 public override FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
1033                 {
1034                         //
1035                         // Only simple names (no dots) will be looked up with this function
1036                         //
1037                         FullNamedExpression resolved;
1038                         for (NamespaceContainer container = this; container != null; container = container.Parent) {
1039                                 resolved = container.Lookup (name, arity, mode, loc);
1040                                 if (resolved != null || container.MemberName == null)
1041                                         return resolved;
1042
1043                                 var container_ns = container.ns.Parent;
1044                                 var mn = container.MemberName.Left;
1045                                 while (mn != null) {
1046                                         resolved = container_ns.LookupTypeOrNamespace (this, name, arity, mode, loc);
1047                                         if (resolved != null)
1048                                                 return resolved;
1049
1050                                         mn = mn.Left;
1051                                         container_ns = container_ns.Parent;
1052                                 }
1053                         }
1054
1055                         return null;
1056                 }
1057
1058                 public override void GetCompletionStartingWith (string prefix, List<string> results)
1059                 {
1060                         foreach (var un in Usings) {
1061                                 if (un.Alias != null)
1062                                         continue;
1063
1064                                 var name = un.NamespaceExpression.Name;
1065                                 if (name.StartsWith (prefix))
1066                                         results.Add (name);
1067                         }
1068
1069
1070                         IEnumerable<string> all = Enumerable.Empty<string> ();
1071
1072                         foreach (Namespace using_ns in namespace_using_table) {
1073                                 if (prefix.StartsWith (using_ns.Name)) {
1074                                         int ld = prefix.LastIndexOf ('.');
1075                                         if (ld != -1) {
1076                                                 string rest = prefix.Substring (ld + 1);
1077
1078                                                 all = all.Concat (using_ns.CompletionGetTypesStartingWith (rest));
1079                                         }
1080                                 }
1081                                 all = all.Concat (using_ns.CompletionGetTypesStartingWith (prefix));
1082                         }
1083
1084                         results.AddRange (all);
1085
1086                         base.GetCompletionStartingWith (prefix, results);
1087                 }
1088
1089
1090                 //
1091                 // Looks-up a alias named @name in this and surrounding namespace declarations
1092                 //
1093                 public FullNamedExpression LookupExternAlias (string name)
1094                 {
1095                         if (aliases == null)
1096                                 return null;
1097
1098                         UsingAliasNamespace uan;
1099                         if (aliases.TryGetValue (name, out uan) && uan is UsingExternAlias)
1100                                 return uan.ResolvedExpression;
1101
1102                         return null;
1103                 }
1104
1105                 //
1106                 // Looks-up a alias named @name in this and surrounding namespace declarations
1107                 //
1108                 public override FullNamedExpression LookupNamespaceAlias (string name)
1109                 {
1110                         for (NamespaceContainer n = this; n != null; n = n.Parent) {
1111                                 if (n.aliases == null)
1112                                         continue;
1113
1114                                 UsingAliasNamespace uan;
1115                                 if (n.aliases.TryGetValue (name, out uan))
1116                                         return uan.ResolvedExpression;
1117                         }
1118
1119                         return null;
1120                 }
1121
1122                 FullNamedExpression Lookup (string name, int arity, LookupMode mode, Location loc)
1123                 {
1124                         //
1125                         // Check whether it's in the namespace.
1126                         //
1127                         FullNamedExpression fne = ns.LookupTypeOrNamespace (this, name, arity, mode, loc);
1128
1129                         //
1130                         // Check aliases.
1131                         //
1132                         if (aliases != null && arity == 0) {
1133                                 UsingAliasNamespace uan;
1134                                 if (aliases.TryGetValue (name, out uan)) {
1135                                         if (fne != null) {
1136                                                 // TODO: Namespace has broken location
1137                                                 //Report.SymbolRelatedToPreviousError (fne.Location, null);
1138                                                 Compiler.Report.SymbolRelatedToPreviousError (uan.Location, null);
1139                                                 Compiler.Report.Error (576, loc,
1140                                                         "Namespace `{0}' contains a definition with same name as alias `{1}'",
1141                                                         GetSignatureForError (), name);
1142                                         }
1143
1144                                         return uan.ResolvedExpression;
1145                                 }
1146                         }
1147
1148                         if (fne != null)
1149                                 return fne;
1150
1151                         //
1152                         // Lookup can be called before the namespace is defined from different namespace using alias clause
1153                         //
1154                         if (namespace_using_table == null) {
1155                                 DoDefineNamespace ();
1156                         }
1157
1158                         //
1159                         // Check using entries.
1160                         //
1161                         FullNamedExpression match = null;
1162                         foreach (Namespace using_ns in namespace_using_table) {
1163                                 //
1164                                 // A using directive imports only types contained in the namespace, it
1165                                 // does not import any nested namespaces
1166                                 //
1167                                 fne = using_ns.LookupType (this, name, arity, mode, loc);
1168                                 if (fne == null)
1169                                         continue;
1170
1171                                 if (match == null) {
1172                                         match = fne;
1173                                         continue;
1174                                 }
1175
1176                                 // Prefer types over namespaces
1177                                 var texpr_fne = fne as TypeExpr;
1178                                 var texpr_match = match as TypeExpr;
1179                                 if (texpr_fne != null && texpr_match == null) {
1180                                         match = fne;
1181                                         continue;
1182                                 } else if (texpr_fne == null) {
1183                                         continue;
1184                                 }
1185
1186                                 // It can be top level accessibility only
1187                                 var better = Namespace.IsImportedTypeOverride (Module, texpr_match.Type, texpr_fne.Type);
1188                                 if (better == null) {
1189                                         if (mode == LookupMode.Normal) {
1190                                                 Compiler.Report.SymbolRelatedToPreviousError (texpr_match.Type);
1191                                                 Compiler.Report.SymbolRelatedToPreviousError (texpr_fne.Type);
1192                                                 Compiler.Report.Error (104, loc, "`{0}' is an ambiguous reference between `{1}' and `{2}'",
1193                                                         name, texpr_match.GetSignatureForError (), texpr_fne.GetSignatureForError ());
1194                                         }
1195
1196                                         return match;
1197                                 }
1198
1199                                 if (better == texpr_fne.Type)
1200                                         match = texpr_fne;
1201                         }
1202
1203                         return match;
1204                 }
1205
1206                 protected override void DefineNamespace ()
1207                 {
1208                         if (namespace_using_table == null)
1209                                 DoDefineNamespace ();
1210
1211                         base.DefineNamespace ();
1212                 }
1213
1214                 void DoDefineNamespace ()
1215                 {
1216                         namespace_using_table = empty_namespaces;
1217
1218                         if (clauses != null) {
1219                                 var list = new List<Namespace> (clauses.Count);
1220                                 bool post_process_using_aliases = false;
1221
1222                                 for (int i = 0; i < clauses.Count; ++i) {
1223                                         var entry = clauses[i];
1224
1225                                         if (entry.Alias != null) {
1226                                                 if (aliases == null)
1227                                                         aliases = new Dictionary<string, UsingAliasNamespace> ();
1228
1229                                                 //
1230                                                 // Aliases are not available when resolving using section
1231                                                 // except extern aliases
1232                                                 //
1233                                                 if (entry is UsingExternAlias) {
1234                                                         entry.Define (this);
1235                                                         if (entry.ResolvedExpression != null)
1236                                                                 aliases.Add (entry.Alias.Value, (UsingExternAlias) entry);
1237
1238                                                         clauses.RemoveAt (i--);
1239                                                 } else {
1240                                                         post_process_using_aliases = true;
1241                                                 }
1242
1243                                                 continue;
1244                                         }
1245
1246                                         entry.Define (this);
1247
1248                                         //
1249                                         // It's needed for repl only, when using clause cannot be resolved don't hold it in
1250                                         // global list which is resolved for each evaluation
1251                                         //
1252                                         if (entry.ResolvedExpression == null) {
1253                                                 clauses.RemoveAt (i--);
1254                                                 continue;
1255                                         }
1256
1257                                         Namespace using_ns = entry.ResolvedExpression as Namespace;
1258                                         if (using_ns == null)
1259                                                 continue;
1260
1261                                         if (list.Contains (using_ns)) {
1262                                                 // Ensure we don't report the warning multiple times in repl
1263                                                 clauses.RemoveAt (i--);
1264
1265                                                 Compiler.Report.Warning (105, 3, entry.Location,
1266                                                         "The using directive for `{0}' appeared previously in this namespace", using_ns.GetSignatureForError ());
1267                                         } else {
1268                                                 list.Add (using_ns);
1269                                         }
1270                                 }
1271
1272                                 namespace_using_table = list.ToArray ();
1273
1274                                 if (post_process_using_aliases) {
1275                                         for (int i = 0; i < clauses.Count; ++i) {
1276                                                 var entry = clauses[i];
1277                                                 if (entry.Alias != null) {
1278                                                         entry.Define (this);
1279                                                         if (entry.ResolvedExpression != null) {
1280                                                                 aliases.Add (entry.Alias.Value, (UsingAliasNamespace) entry);
1281                                                         }
1282
1283                                                         clauses.RemoveAt (i--);
1284                                                 }
1285                                         }
1286                                 }
1287                         }
1288                 }
1289
1290                 public void EnableRedefinition ()
1291                 {
1292                         is_defined = false;
1293                         namespace_using_table = null;
1294                 }
1295
1296                 internal override void GenerateDocComment (DocumentationBuilder builder)
1297                 {
1298                         if (containers != null) {
1299                                 foreach (var tc in containers)
1300                                         tc.GenerateDocComment (builder);
1301                         }
1302                 }
1303
1304                 public override string GetSignatureForError ()
1305                 {
1306                         return MemberName == null ? "global::" : base.GetSignatureForError ();
1307                 }
1308
1309                 public override void RemoveContainer (TypeContainer cont)
1310                 {
1311                         base.RemoveContainer (cont);
1312                         NS.RemoveContainer (cont);
1313                 }
1314
1315                 protected override bool VerifyClsCompliance ()
1316                 {
1317                         if (Module.IsClsComplianceRequired ()) {
1318                                 if (MemberName != null && MemberName.Name[0] == '_') {
1319                                         Warning_IdentifierNotCompliant ();
1320                                 }
1321
1322                                 ns.VerifyClsCompliance ();
1323                                 return true;
1324                         }
1325
1326                         return false;
1327                 }
1328         }
1329
1330         public class UsingNamespace
1331         {
1332                 readonly ATypeNameExpression expr;
1333                 readonly Location loc;
1334                 protected FullNamedExpression resolved;
1335
1336                 public UsingNamespace (ATypeNameExpression expr, Location loc)
1337                 {
1338                         this.expr = expr;
1339                         this.loc = loc;
1340                 }
1341
1342                 #region Properties
1343
1344                 public virtual SimpleMemberName Alias {
1345                         get {
1346                                 return null;
1347                         }
1348                 }
1349
1350                 public Location Location {
1351                         get {
1352                                 return loc;
1353                         }
1354                 }
1355
1356                 public ATypeNameExpression NamespaceExpression  {
1357                         get {
1358                                 return expr;
1359                         }
1360                 }
1361
1362                 public FullNamedExpression ResolvedExpression {
1363                         get {
1364                                 return resolved;
1365                         }
1366                 }
1367
1368                 #endregion
1369
1370                 public string GetSignatureForError ()
1371                 {
1372                         return expr.GetSignatureForError ();
1373                 }
1374
1375                 public virtual void Define (NamespaceContainer ctx)
1376                 {
1377                         resolved = expr.ResolveAsTypeOrNamespace (ctx);
1378                         var ns = resolved as Namespace;
1379                         if (ns == null) {
1380                                 if (resolved != null) {
1381                                         ctx.Module.Compiler.Report.SymbolRelatedToPreviousError (resolved.Type);
1382                                         ctx.Module.Compiler.Report.Error (138, Location,
1383                                                 "`{0}' is a type not a namespace. A using namespace directive can only be applied to namespaces",
1384                                                 GetSignatureForError ());
1385                                 }
1386                         }
1387                 }
1388         }
1389
1390         public class UsingExternAlias : UsingAliasNamespace
1391         {
1392                 public UsingExternAlias (SimpleMemberName alias, Location loc)
1393                         : base (alias, null, loc)
1394                 {
1395                 }
1396
1397                 public override void Define (NamespaceContainer ctx)
1398                 {
1399                         resolved = ctx.Module.GetRootNamespace (Alias.Value);
1400                         if (resolved == null) {
1401                                 ctx.Module.Compiler.Report.Error (430, Location,
1402                                         "The extern alias `{0}' was not specified in -reference option",
1403                                         Alias.Value);
1404                         }
1405                 }
1406         }
1407
1408         public class UsingAliasNamespace : UsingNamespace
1409         {
1410                 readonly SimpleMemberName alias;
1411
1412                 public struct AliasContext : IMemberContext
1413                 {
1414                         readonly NamespaceContainer ns;
1415
1416                         public AliasContext (NamespaceContainer ns)
1417                         {
1418                                 this.ns = ns;
1419                         }
1420
1421                         public TypeSpec CurrentType {
1422                                 get {
1423                                         return null;
1424                                 }
1425                         }
1426
1427                         public TypeParameters CurrentTypeParameters {
1428                                 get {
1429                                         return null;
1430                                 }
1431                         }
1432
1433                         public MemberCore CurrentMemberDefinition {
1434                                 get {
1435                                         return null;
1436                                 }
1437                         }
1438
1439                         public bool IsObsolete {
1440                                 get {
1441                                         return false;
1442                                 }
1443                         }
1444
1445                         public bool IsUnsafe {
1446                                 get {
1447                                         throw new NotImplementedException ();
1448                                 }
1449                         }
1450
1451                         public bool IsStatic {
1452                                 get {
1453                                         throw new NotImplementedException ();
1454                                 }
1455                         }
1456
1457                         public ModuleContainer Module {
1458                                 get {
1459                                         return ns.Module;
1460                                 }
1461                         }
1462
1463                         public string GetSignatureForError ()
1464                         {
1465                                 throw new NotImplementedException ();
1466                         }
1467
1468                         public ExtensionMethodCandidates LookupExtensionMethod (TypeSpec extensionType, string name, int arity)
1469                         {
1470                                 return null;
1471                         }
1472
1473                         public FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
1474                         {
1475                                 var fne = ns.NS.LookupTypeOrNamespace (ns, name, arity, mode, loc);
1476                                 if (fne != null)
1477                                         return fne;
1478
1479                                 //
1480                                 // Only extern aliases are allowed in this context
1481                                 //
1482                                 fne = ns.LookupExternAlias (name);
1483                                 if (fne != null || ns.MemberName == null)
1484                                         return fne;
1485
1486                                 var container_ns = ns.NS.Parent;
1487                                 var mn = ns.MemberName.Left;
1488                                 while (mn != null) {
1489                                         fne = container_ns.LookupTypeOrNamespace (this, name, arity, mode, loc);
1490                                         if (fne != null)
1491                                                 return fne;
1492
1493                                         mn = mn.Left;
1494                                         container_ns = container_ns.Parent;
1495                                 }
1496
1497                                 if (ns.Parent != null)
1498                                         return ns.Parent.LookupNamespaceOrType (name, arity, mode, loc);
1499
1500                                 return null;
1501                         }
1502
1503                         public FullNamedExpression LookupNamespaceAlias (string name)
1504                         {
1505                                 return ns.LookupNamespaceAlias (name);
1506                         }
1507                 }
1508
1509                 public UsingAliasNamespace (SimpleMemberName alias, ATypeNameExpression expr, Location loc)
1510                         : base (expr, loc)
1511                 {
1512                         this.alias = alias;
1513                 }
1514
1515                 public override SimpleMemberName Alias {
1516                         get {
1517                                 return alias;
1518                         }
1519                 }
1520
1521                 public override void Define (NamespaceContainer ctx)
1522                 {
1523                         //
1524                         // The namespace-or-type-name of a using-alias-directive is resolved as if
1525                         // the immediately containing compilation unit or namespace body had no
1526                         // using-directives. A using-alias-directive may however be affected
1527                         // by extern-alias-directives in the immediately containing compilation
1528                         // unit or namespace body
1529                         //
1530                         // We achieve that by introducing alias-context which redirect any local
1531                         // namespace or type resolve calls to parent namespace
1532                         //
1533                         resolved = NamespaceExpression.ResolveAsTypeOrNamespace (new AliasContext (ctx));
1534                 }
1535         }
1536 }