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 // (C) 2001 Ximian, Inc.
   9 //
  10 using System;
  11 using System.Collections;
  12 using System.Collections.Specialized;
  13 using System.Reflection;
  14
  15 namespace Mono.CSharp {
  16
  17         public class RootNamespace : Namespace {
  18                 static MethodInfo get_namespaces_method;
  19
  20                 string alias_name;
  21                 Assembly referenced_assembly;
  22
  23                 Hashtable all_namespaces;
  24
  25                 static Hashtable root_namespaces;
  26                 public static GlobalRootNamespace Global;
  27
  28                 static RootNamespace ()
  29                 {
  30                         get_namespaces_method = typeof (Assembly).GetMethod ("GetNamespaces", BindingFlags.Instance | BindingFlags.NonPublic);
  31
  32                         Reset ();
  33                 }
  34
  35                 public static void Reset ()
  36                 {
  37                         root_namespaces = new Hashtable ();
  38                         Global = new GlobalRootNamespace ();
  39                         root_namespaces ["global"] = Global;
  40                 }
  41
  42                 protected RootNamespace (string alias_name, Assembly assembly)
  43                         : base (null, String.Empty)
  44                 {
  45                         this.alias_name = alias_name;
  46                         referenced_assembly = assembly;
  47
  48                         all_namespaces = new Hashtable ();
  49                         all_namespaces.Add ("", this);
  50
  51                         if (referenced_assembly != null)
  52                                 ComputeNamespaces (this.referenced_assembly);
  53                 }
  54
  55                 public static void DefineRootNamespace (string name, Assembly assembly)
  56                 {
  57                         if (name == "global") {
  58                                 // FIXME: Add proper error number
  59                                 Report.Error (-42, "Cannot define an external alias named `global'");
  60                                 return;
  61                         }
  62                         RootNamespace retval = GetRootNamespace (name);
  63                         if (retval == null || retval.referenced_assembly != assembly)
  64                                 root_namespaces [name] = new RootNamespace (name, assembly);
  65                 }
  66
  67                 public static RootNamespace GetRootNamespace (string name)
  68                 {
  69                         return (RootNamespace) root_namespaces [name];
  70                 }
  71
  72                 public virtual Type LookupTypeReflection (string name, Location loc)
  73                 {
  74                         return GetTypeInAssembly (referenced_assembly, name);
  75                 }
  76
  77                 public void RegisterNamespace (Namespace child)
  78                 {
  79                         if (child != this)
  80                                 all_namespaces.Add (child.Name, child);
  81                 }
  82
  83                 public bool IsNamespace (string name)
  84                 {
  85                         return all_namespaces.Contains (name);
  86                 }
  87
  88                 protected void EnsureNamespace (string dotted_name)
  89                 {
  90                         if (dotted_name != null && dotted_name.Length != 0 && ! IsNamespace (dotted_name))
  91                                 GetNamespace (dotted_name, true);
  92                 }
  93
  94                 protected void ComputeNamespaces (Assembly assembly)
  95                 {
  96                         if (get_namespaces_method != null) {
  97                                 string [] namespaces = (string []) get_namespaces_method.Invoke (assembly, null);
  98                                 foreach (string ns in namespaces)
  99                                         EnsureNamespace (ns);
 100                                 return;
 101                         }
 102
 103                         foreach (Type t in assembly.GetExportedTypes ())
 104                                 EnsureNamespace (t.Namespace);
 105                 }
 106
 107                 protected static Type GetTypeInAssembly (Assembly assembly, string name)
 108                 {
 109                         Type t = assembly.GetType (name);
 110                         if (t == null)
 111                                 return null;
 112
 113                         if (t.IsPointer)
 114                                 throw new InternalErrorException ("Use GetPointerType() to get a pointer");
 115
 116                         TypeAttributes ta = t.Attributes & TypeAttributes.VisibilityMask;
 117                         if (ta == TypeAttributes.NestedPrivate)
 118                                 return null;
 119
 120                         if ((ta == TypeAttributes.NotPublic ||
 121                              ta == TypeAttributes.NestedAssembly ||
 122                              ta == TypeAttributes.NestedFamANDAssem) &&
 123                             !TypeManager.IsFriendAssembly (t.Assembly))
 124                                 return null;
 125
 126                         return t;
 127                 }
 128
 129                 public override string ToString ()
 130                 {
 131                         return String.Format ("RootNamespace ({0}::)", alias_name);
 132                 }
 133
 134                 public override string GetSignatureForError ()
 135                 {
 136                         return alias_name + "::";
 137                 }
 138         }
 139
 140         public class GlobalRootNamespace : RootNamespace {
 141                 Assembly [] assemblies;
 142                 Module [] modules;
 143
 144                 public GlobalRootNamespace ()
 145                         : base ("global", null)
 146                 {
 147                         assemblies = new Assembly [0];
 148                 }
 149
 150                 public Assembly [] Assemblies {
 151                         get { return assemblies; }
 152                 }
 153
 154                 public Module [] Modules {
 155                         get { return modules; }
 156                 }
 157
 158                 public void AddAssemblyReference (Assembly a)
 159                 {
 160                         foreach (Assembly assembly in assemblies) {
 161                                 if (a == assembly)
 162                                         return;
 163                         }
 164
 165                         int top = assemblies.Length;
 166                         Assembly [] n = new Assembly [top + 1];
 167                         assemblies.CopyTo (n, 0);
 168                         n [top] = a;
 169                         assemblies = n;
 170
 171                         ComputeNamespaces (a);
 172                 }
 173
 174                 public void AddModuleReference (Module m)
 175                 {
 176                         int top = modules != null ? modules.Length : 0;
 177                         Module [] n = new Module [top + 1];
 178                         if (modules != null)
 179                                 modules.CopyTo (n, 0);
 180                         n [top] = m;
 181                         modules = n;
 182
 183                         if (m == CodeGen.Module.Builder)
 184                                 return;
 185
 186                         foreach (Type t in m.GetTypes ())
 187                                 EnsureNamespace (t.Namespace);
 188                 }
 189
 190                 public override void Error_NamespaceDoesNotExist(DeclSpace ds, Location loc, string name)
 191                 {
 192                         Report.Error (400, loc, "The type or namespace name `{0}' could not be found in the global namespace (are you missing an assembly reference?)",
 193                                 name);
 194                 }
 195
 196                 public override Type LookupTypeReflection (string name, Location loc)
 197                 {
 198                         Type found_type = null;
 199
 200                         foreach (Assembly a in assemblies) {
 201                                 Type t = GetTypeInAssembly (a, name);
 202                                 if (t == null)
 203                                         continue;
 204
 205                                 if (found_type == null) {
 206                                         found_type = t;
 207                                         continue;
 208                                 }
 209
 210                                 Report.SymbolRelatedToPreviousError (found_type);
 211                                 Report.SymbolRelatedToPreviousError (t);
 212                                 Report.Error (433, loc, "The imported type `{0}' is defined multiple times", name);
 213
 214                                 return found_type;
 215                         }
 216
 217                         if (modules != null) {
 218                                 foreach (Module module in modules) {
 219                                         Type t = module.GetType (name);
 220                                         if (t == null)
 221                                                 continue;
 222
 223                                         if (found_type == null) {
 224                                                 found_type = t;
 225                                                 continue;
 226                                         }
 227
 228                                         Report.SymbolRelatedToPreviousError (t);
 229                                         Report.SymbolRelatedToPreviousError (found_type);
 230                                         Report.Warning (436, 2, loc, "Ignoring imported type `{0}' since the current assembly already has a declaration with the same name",
 231                                                 TypeManager.CSharpName (t));
 232                                         return t;
 233                                 }
 234                         }
 235
 236                         return found_type;
 237                 }
 238         }
 239
 240         /// <summary>
 241         ///   Keeps track of the namespaces defined in the C# code.
 242         ///
 243         ///   This is an Expression to allow it to be referenced in the
 244         ///   compiler parse/intermediate tree during name resolution.
 245         /// </summary>
 246         public class Namespace : FullNamedExpression {
 247
 248                 Namespace parent;
 249                 string fullname;
 250                 Hashtable namespaces;
 251                 IDictionary declspaces;
 252                 Hashtable cached_types;
 253                 RootNamespace root;
 254
 255                 public readonly MemberName MemberName;
 256
 257                 /// <summary>
 258                 ///   Constructor Takes the current namespace and the
 259                 ///   name.  This is bootstrapped with parent == null
 260                 ///   and name = ""
 261                 /// </summary>
 262                 public Namespace (Namespace parent, string name)
 263                 {
 264                         // Expression members.
 265                         this.eclass = ExprClass.Namespace;
 266                         this.Type = null;
 267                         this.loc = Location.Null;
 268
 269                         this.parent = parent;
 270
 271                         if (parent != null)
 272                                 this.root = parent.root;
 273                         else
 274                                 this.root = this as RootNamespace;
 275
 276                         if (this.root == null)
 277                                 throw new InternalErrorException ("Root namespaces must be created using RootNamespace");
 278
 279                         string pname = parent != null ? parent.Name : "";
 280
 281                         if (pname == "")
 282                                 fullname = name;
 283                         else
 284                                 fullname = parent.Name + "." + name;
 285
 286                         if (fullname == null)
 287                                 throw new InternalErrorException ("Namespace has a null fullname");
 288
 289                         if (parent != null && parent.MemberName != MemberName.Null)
 290                                 MemberName = new MemberName (parent.MemberName, name);
 291                         else if (name.Length == 0)
 292                                 MemberName = MemberName.Null;
 293                         else
 294                                 MemberName = new MemberName (name);
 295
 296                         namespaces = new Hashtable ();
 297                         cached_types = new Hashtable ();
 298
 299                         root.RegisterNamespace (this);
 300                 }
 301
 302                 public override Expression DoResolve (EmitContext ec)
 303                 {
 304                         return this;
 305                 }
 306
 307                 public virtual void Error_NamespaceDoesNotExist (DeclSpace ds, Location loc, string name)
 308                 {
 309                         if (name.IndexOf ("`") > 0) {
 310                                 FullNamedExpression retval = Lookup (ds, SimpleName.RemoveGenericArity (name), loc);
 311                                 if (retval != null) {
 312                                         Error_TypeArgumentsCannotBeUsed(retval.Type, loc, "type");
 313                                         return;
 314                                 }
 315                         } else {
 316                                 Type t = LookForAnyGenericType (name);
 317                                 if (t != null) {
 318                                         Error_InvalidNumberOfTypeArguments(t, loc);
 319                                         return;
 320                                 }
 321                         }
 322
 323                         Report.Error (234, loc, "The type or namespace name `{0}' does not exist in the namespace `{1}'. Are you missing an assembly reference?",
 324                                 name, FullName);
 325                 }
 326
 327                 public static void Error_InvalidNumberOfTypeArguments (Type t, Location loc)
 328                 {
 329                         Report.SymbolRelatedToPreviousError (t);
 330                         Report.Error (305, loc, "Using the generic type `{0}' requires `{1}' type argument(s)",
 331                                 TypeManager.CSharpName(t), TypeManager.GetNumberOfTypeArguments(t).ToString());
 332                 }
 333
 334                 public static void Error_TypeArgumentsCannotBeUsed(Type t, Location loc, string symbol)
 335                 {
 336                         Report.SymbolRelatedToPreviousError(t);
 337                         Report.Error(308, loc, "The non-generic {0} `{1}' cannot be used with the type argument(s)",
 338                                 symbol, TypeManager.CSharpName(t));
 339                 }
 340
 341                 public override void Emit (EmitContext ec)
 342                 {
 343                         throw new InternalErrorException ("Expression tree referenced namespace " + fullname + " during Emit ()");
 344                 }
 345
 346                 public override string GetSignatureForError ()
 347                 {
 348                         return Name;
 349                 }
 350
 351                 public Namespace GetNamespace (string name, bool create)
 352                 {
 353                         int pos = name.IndexOf ('.');
 354
 355                         Namespace ns;
 356                         string first;
 357                         if (pos >= 0)
 358                                 first = name.Substring (0, pos);
 359                         else
 360                                 first = name;
 361
 362                         ns = (Namespace) namespaces [first];
 363                         if (ns == null) {
 364                                 if (!create)
 365                                         return null;
 366
 367                                 ns = new Namespace (this, first);
 368                                 namespaces.Add (first, ns);
 369                         }
 370
 371                         if (pos >= 0)
 372                                 ns = ns.GetNamespace (name.Substring (pos + 1), create);
 373
 374                         return ns;
 375                 }
 376
 377                 TypeExpr LookupType (string name, Location loc)
 378                 {
 379                         if (cached_types.Contains (name))
 380                                 return cached_types [name] as TypeExpr;
 381
 382                         Type t = null;
 383                         if (declspaces != null) {
 384                                 DeclSpace tdecl = declspaces [name] as DeclSpace;
 385                                 if (tdecl != null) {
 386                                         //
 387                                         // Note that this is not:
 388                                         //
 389                                         //   t = tdecl.DefineType ()
 390                                         //
 391                                         // This is to make it somewhat more useful when a DefineType
 392                                         // fails due to problems in nested types (more useful in the sense
 393                                         // of fewer misleading error messages)
 394                                         //
 395                                         tdecl.DefineType ();
 396                                         t = tdecl.TypeBuilder;
 397                                 }
 398                         }
 399                         string lookup = t != null ? t.FullName : (fullname.Length == 0 ? name : fullname + "." + name);
 400                         Type rt = root.LookupTypeReflection (lookup, loc);
 401                         if (t == null)
 402                                 t = rt;
 403
 404                         TypeExpr te = t == null ? null : new TypeExpression (t, Location.Null);
 405                         cached_types [name] = te;
 406                         return te;
 407                 }
 408
 409                 ///
 410                 /// Used for better error reporting only
 411                 ///
 412                 public Type LookForAnyGenericType (string typeName)
 413                 {
 414                         typeName = SimpleName.RemoveGenericArity(typeName);
 415
 416                         foreach (string type_item in declspaces.Keys) {
 417                                 string[] sep_type = type_item.Split('`');
 418                                 if (sep_type.Length < 2)
 419                                         continue;
 420
 421                                 if (typeName == sep_type [0]) {
 422                                         DeclSpace tdecl = (DeclSpace)declspaces [type_item];
 423                                         return tdecl.TypeBuilder;
 424                                 }
 425                         }
 426                         return null;
 427                 }
 428
 429                 public FullNamedExpression Lookup (DeclSpace ds, string name, Location loc)
 430                 {
 431                         if (namespaces.Contains (name))
 432                                 return (Namespace) namespaces [name];
 433
 434                         TypeExpr te = LookupType (name, loc);
 435                         if (te == null || !ds.CheckAccessLevel (te.Type))
 436                                 return null;
 437
 438                         return te;
 439                 }
 440
 441                 public void AddDeclSpace (string name, DeclSpace ds)
 442                 {
 443                         if (declspaces == null)
 444                                 declspaces = new HybridDictionary ();
 445                         declspaces.Add (name, ds);
 446                 }
 447
 448                 /// <summary>
 449                 ///   The qualified name of the current namespace
 450                 /// </summary>
 451                 public string Name {
 452                         get { return fullname; }
 453                 }
 454
 455                 public override string FullName {
 456                         get { return fullname; }
 457                 }
 458
 459                 /// <summary>
 460                 ///   The parent of this namespace, used by the parser to "Pop"
 461                 ///   the current namespace declaration
 462                 /// </summary>
 463                 public Namespace Parent {
 464                         get { return parent; }
 465                 }
 466
 467                 public override string ToString ()
 468                 {
 469                         return String.Format ("Namespace ({0})", Name);
 470                 }
 471         }
 472
 473         public class NamespaceEntry {
 474                 Namespace ns;
 475                 NamespaceEntry parent, implicit_parent;
 476                 SourceFile file;
 477                 int symfile_id;
 478                 Hashtable aliases;
 479                 ArrayList using_clauses;
 480                 public bool DeclarationFound = false;
 481                 bool UsingFound;
 482
 483                 public readonly DeclSpace SlaveDeclSpace;
 484
 485                 ListDictionary extern_aliases;
 486
 487                 static ArrayList entries = new ArrayList ();
 488
 489                 public static void Reset ()
 490                 {
 491                         entries = new ArrayList ();
 492                 }
 493
 494                 //
 495                 // This class holds the location where a using definition is
 496                 // done, and whether it has been used by the program or not.
 497                 //
 498                 // We use this to flag using clauses for namespaces that do not
 499                 // exist.
 500                 //
 501                 public class UsingEntry : IResolveContext {
 502                         public readonly MemberName Name;
 503                         readonly Expression Expr;
 504                         readonly NamespaceEntry NamespaceEntry;
 505                         readonly Location Location;
 506
 507                         public UsingEntry (NamespaceEntry entry, MemberName name, Location loc)
 508                         {
 509                                 Name = name;
 510                                 Expr = name.GetTypeExpression ();
 511                                 NamespaceEntry = entry;
 512                                 Location = loc;
 513                         }
 514
 515                         internal Namespace resolved;
 516
 517                         public Namespace Resolve ()
 518                         {
 519                                 if (resolved != null)
 520                                         return resolved;
 521
 522                                 FullNamedExpression fne = Expr.ResolveAsTypeStep (this, false);
 523                                 if (fne == null) {
 524                                         Error_NamespaceNotFound (Location, Name.ToString ());
 525                                         return null;
 526                                 }
 527
 528                                 resolved = fne as Namespace;
 529                                 if (resolved == null) {
 530                                         Report.Error (138, Location,
 531                                                 "`{0} is a type not a namespace. A using namespace directive can only be applied to namespaces", Name.ToString ());
 532                                 }
 533                                 return resolved;
 534                         }
 535
 536                         DeclSpace IResolveContext.DeclContainer {
 537                                 get { return NamespaceEntry.SlaveDeclSpace; }
 538                         }
 539
 540                         DeclSpace IResolveContext.GenericDeclContainer {
 541                                 get { return NamespaceEntry.SlaveDeclSpace; }
 542                         }
 543
 544                         bool IResolveContext.IsInObsoleteScope {
 545                                 get { return false; }
 546                         }
 547                         bool IResolveContext.IsInUnsafeScope {
 548                                 get { return false; }
 549                         }
 550                 }
 551
 552                 public abstract class AliasEntry {
 553                         public readonly string Name;
 554                         public readonly NamespaceEntry NamespaceEntry;
 555                         public readonly Location Location;
 556
 557                         protected AliasEntry (NamespaceEntry entry, string name, Location loc)
 558                         {
 559                                 Name = name;
 560                                 NamespaceEntry = entry;
 561                                 Location = loc;
 562                         }
 563
 564                         protected FullNamedExpression resolved;
 565                         bool error;
 566
 567                         public FullNamedExpression Resolve ()
 568                         {
 569                                 if (resolved != null || error)
 570                                         return resolved;
 571                                 resolved = DoResolve ();
 572                                 if (resolved == null)
 573                                         error = true;
 574                                 return resolved;
 575                         }
 576
 577                         protected abstract FullNamedExpression DoResolve ();
 578                 }
 579
 580                 public class LocalAliasEntry : AliasEntry, IResolveContext {
 581                         public readonly Expression Alias;
 582
 583                         public LocalAliasEntry (NamespaceEntry entry, string name, MemberName alias, Location loc) :
 584                                 base (entry, name, loc)
 585                         {
 586                                 Alias = alias.GetTypeExpression ();
 587                         }
 588
 589                         protected override FullNamedExpression DoResolve ()
 590                         {
 591                                 resolved = Alias.ResolveAsTypeStep (this, false);
 592                                 if (resolved == null)
 593                                         return null;
 594
 595                                 if (resolved.Type != null) {
 596                                         TypeAttributes attr = resolved.Type.Attributes & TypeAttributes.VisibilityMask;
 597                                         if (attr == TypeAttributes.NestedPrivate || attr == TypeAttributes.NestedFamily ||
 598                                                 ((attr == TypeAttributes.NestedFamORAssem || attr == TypeAttributes.NestedAssembly) &&
 599                                                 TypeManager.LookupDeclSpace (resolved.Type) == null)) {
 600                                                 Expression.ErrorIsInaccesible (Alias.Location, Alias.ToString ());
 601                                                 return null;
 602                                         }
 603                                 }
 604
 605                                 return resolved;
 606                         }
 607
 608                         DeclSpace IResolveContext.DeclContainer {
 609                                 get { return NamespaceEntry.SlaveDeclSpace; }
 610                         }
 611
 612                         DeclSpace IResolveContext.GenericDeclContainer {
 613                                 get { return NamespaceEntry.SlaveDeclSpace; }
 614                         }
 615
 616                         bool IResolveContext.IsInObsoleteScope {
 617                                 get { return false; }
 618                         }
 619                         bool IResolveContext.IsInUnsafeScope {
 620                                 get { return false; }
 621                         }
 622                 }
 623
 624                 public class ExternAliasEntry : AliasEntry {
 625                         public ExternAliasEntry (NamespaceEntry entry, string name, Location loc) :
 626                                 base (entry, name, loc)
 627                         {
 628                         }
 629
 630                         protected override FullNamedExpression DoResolve ()
 631                         {
 632                                 resolved = RootNamespace.GetRootNamespace (Name);
 633                                 if (resolved == null)
 634                                         Report.Error (430, Location, "The extern alias '" + Name +
 635                                                                         "' was not specified in a /reference option");
 636
 637                                 return resolved;
 638                         }
 639                 }
 640
 641                 public NamespaceEntry (NamespaceEntry parent, SourceFile file, string name)
 642                 {
 643                         this.parent = parent;
 644                         this.file = file;
 645                         entries.Add (this);
 646                         this.ID = entries.Count;
 647
 648                         if (parent != null)
 649                                 ns = parent.NS.GetNamespace (name, true);
 650                         else if (name != null)
 651                                 ns = RootNamespace.Global.GetNamespace (name, true);
 652                         else
 653                                 ns = RootNamespace.Global;
 654                         SlaveDeclSpace = new RootDeclSpace (this);
 655                 }
 656
 657                 private NamespaceEntry (NamespaceEntry parent, SourceFile file, Namespace ns, bool slave)
 658                 {
 659                         this.parent = parent;
 660                         this.file = file;
 661                         // no need to add self to 'entries', since we don't have any aliases or using entries.
 662                         this.ID = -1;
 663                         this.IsImplicit = true;
 664                         this.ns = ns;
 665                         this.SlaveDeclSpace = slave ? new RootDeclSpace (this) : null;
 666                 }
 667
 668                 //
 669                 // According to section 16.3.1 (using-alias-directive), the namespace-or-type-name is
 670                 // resolved as if the immediately containing namespace body has no using-directives.
 671                 //
 672                 // Section 16.3.2 says that the same rule is applied when resolving the namespace-name
 673                 // in the using-namespace-directive.
 674                 //
 675                 // To implement these rules, the expressions in the using directives are resolved using
 676                 // the "doppelganger" (ghostly bodiless duplicate).
 677                 //
 678                 NamespaceEntry doppelganger;
 679                 NamespaceEntry Doppelganger {
 680                         get {
 681                                 if (!IsImplicit && doppelganger == null)
 682                                         doppelganger = new NamespaceEntry (ImplicitParent, file, ns, true);
 683                                 return doppelganger;
 684                         }
 685                 }
 686
 687                 public readonly int ID;
 688                 public readonly bool IsImplicit;
 689
 690                 public Namespace NS {
 691                         get { return ns; }
 692                 }
 693
 694                 public NamespaceEntry Parent {
 695                         get { return parent; }
 696                 }
 697
 698                 public NamespaceEntry ImplicitParent {
 699                         get {
 700                                 if (parent == null)
 701                                         return null;
 702                                 if (implicit_parent == null) {
 703                                         implicit_parent = (parent.NS == ns.Parent)
 704                                                 ? parent
 705                                                 : new NamespaceEntry (parent, file, ns.Parent, false);
 706                                 }
 707                                 return implicit_parent;
 708                         }
 709                 }
 710
 711                 /// <summary>
 712                 ///   Records a new namespace for resolving name references
 713                 /// </summary>
 714                 public void Using (MemberName name, Location loc)
 715                 {
 716                         if (DeclarationFound){
 717                                 Report.Error (1529, loc, "A using clause must precede all other namespace elements except extern alias declarations");
 718                                 return;
 719                         }
 720
 721                         UsingFound = true;
 722
 723                         if (name.Equals (ns.MemberName))
 724                                 return;
 725
 726                         if (using_clauses == null)
 727                                 using_clauses = new ArrayList ();
 728
 729                         foreach (UsingEntry old_entry in using_clauses) {
 730                                 if (name.Equals (old_entry.Name)) {
 731                                         Report.Warning (105, 3, loc, "The using directive for `{0}' appeared previously in this namespace", name.GetName ());
 732                                         return;
 733                                 }
 734                         }
 735
 736                         UsingEntry ue = new UsingEntry (Doppelganger, name, loc);
 737                         using_clauses.Add (ue);
 738                 }
 739
 740                 public void UsingAlias (string name, MemberName alias, Location loc)
 741                 {
 742                         if (DeclarationFound){
 743                                 Report.Error (1529, loc, "A using clause must precede all other namespace elements except extern alias declarations");
 744                                 return;
 745                         }
 746
 747                         UsingFound = true;
 748
 749                         if (aliases == null)
 750                                 aliases = new Hashtable ();
 751
 752                         if (aliases.Contains (name)) {
 753                                 AliasEntry ae = (AliasEntry) aliases [name];
 754                                 Report.SymbolRelatedToPreviousError (ae.Location, ae.Name);
 755                                 Report.Error (1537, loc, "The using alias `{0}' appeared previously in this namespace", name);
 756                                 return;
 757                         }
 758
 759                         if (RootContext.Version == LanguageVersion.Default &&
 760                             name == "global" && RootContext.WarningLevel >= 2)
 761                                 Report.Warning (440, 2, loc, "An alias named `global' will not be used when resolving 'global::';" +
 762                                         " the global namespace will be used instead");
 763
 764                         // FIXME: get correct error number.  See if the above check can be merged
 765                         if (extern_aliases != null && extern_aliases.Contains (name)) {
 766                                 AliasEntry ae = (AliasEntry) extern_aliases [name];
 767                                 Report.SymbolRelatedToPreviousError (ae.Location, ae.Name);
 768                                 Report.Error (1537, loc, "The using alias `{0}' appeared previously in this namespace", name);
 769                                 return;
 770                         }
 771
 772                         aliases [name] = new LocalAliasEntry (Doppelganger, name, alias, loc);
 773                 }
 774
 775                 public void UsingExternalAlias (string name, Location loc)
 776                 {
 777                         if (UsingFound || DeclarationFound) {
 778                                 Report.Error (439, loc, "An extern alias declaration must precede all other elements");
 779                                 return;
 780                         }
 781
 782                         // Share the extern_aliases field with the Doppelganger
 783                         if (extern_aliases == null) {
 784                                 extern_aliases = new ListDictionary ();
 785                                 Doppelganger.extern_aliases = extern_aliases;
 786                         }
 787
 788                         if (extern_aliases.Contains (name)) {
 789                                 AliasEntry ae = (AliasEntry) extern_aliases [name];
 790                                 Report.SymbolRelatedToPreviousError (ae.Location, ae.Name);
 791                                 Report.Error (1537, loc, "The using alias `{0}' appeared previously in this namespace", name);
 792                                 return;
 793                         }
 794
 795                         if (name == "global") {
 796                                 Report.Error (1681, loc, "You cannot redefine the global extern alias");
 797                                 return;
 798                         }
 799
 800                         // Register the alias in aliases and extern_aliases, since we need both of them
 801                         // to keep things simple (different resolution scenarios)
 802                         ExternAliasEntry alias = new ExternAliasEntry (Doppelganger, name, loc);
 803                         extern_aliases [name] = alias;
 804                 }
 805
 806                 public FullNamedExpression LookupNamespaceOrType (DeclSpace ds, string name, Location loc, bool ignore_cs0104)
 807                 {
 808                         // Precondition: Only simple names (no dots) will be looked up with this function.
 809                         FullNamedExpression resolved = null;
 810                         for (NamespaceEntry curr_ns = this; curr_ns != null; curr_ns = curr_ns.ImplicitParent) {
 811                                 if ((resolved = curr_ns.Lookup (ds, name, loc, ignore_cs0104)) != null)
 812                                         break;
 813                         }
 814                         return resolved;
 815                 }
 816
 817                 static void Error_AmbiguousTypeReference (Location loc, string name, FullNamedExpression t1, FullNamedExpression t2)
 818                 {
 819                         Report.Error (104, loc, "`{0}' is an ambiguous reference between `{1}' and `{2}'",
 820                                 name, t1.FullName, t2.FullName);
 821                 }
 822
 823                 // Looks-up a alias named @name in this and surrounding namespace declarations
 824                 public FullNamedExpression LookupAlias (string name)
 825                 {
 826                         AliasEntry entry = null;
 827                         for (NamespaceEntry n = this; n != null; n = n.ImplicitParent) {
 828                                 if (n.extern_aliases != null && (entry = n.extern_aliases [name] as AliasEntry) != null)
 829                                         break;
 830                                 if (n.aliases != null && (entry = n.aliases [name] as AliasEntry) != null)
 831                                         break;
 832                         }
 833                         return entry == null ? null : entry.Resolve ();
 834                 }
 835
 836                 private FullNamedExpression Lookup (DeclSpace ds, string name, Location loc, bool ignore_cs0104)
 837                 {
 838                         //
 839                         // Check whether it's in the namespace.
 840                         //
 841                         FullNamedExpression fne = NS.Lookup (ds, name, loc);
 842                         if (fne != null)
 843                                 return fne;
 844
 845                         if (extern_aliases != null) {
 846                                 AliasEntry entry = extern_aliases [name] as AliasEntry;
 847                                 if (entry != null)
 848                                         return entry.Resolve ();
 849                         }
 850
 851                         if (IsImplicit)
 852                                 return null;
 853
 854                         //
 855                         // Check aliases.
 856                         //
 857                         if (aliases != null) {
 858                                 AliasEntry entry = aliases [name] as AliasEntry;
 859                                 if (entry != null)
 860                                         return entry.Resolve ();
 861                         }
 862
 863                         //
 864                         // Check using entries.
 865                         //
 866                         FullNamedExpression match = null;
 867                         foreach (Namespace using_ns in GetUsingTable ()) {
 868                                 match = using_ns.Lookup (ds, name, loc);
 869                                 if (match == null || !(match is TypeExpr))
 870                                         continue;
 871                                 if (fne != null) {
 872                                         if (!ignore_cs0104)
 873                                                 Error_AmbiguousTypeReference (loc, name, fne, match);
 874                                         return null;
 875                                 }
 876                                 fne = match;
 877                         }
 878
 879                         return fne;
 880                 }
 881
 882                 // Our cached computation.
 883                 readonly Namespace [] empty_namespaces = new Namespace [0];
 884                 Namespace [] namespace_using_table;
 885                 Namespace [] GetUsingTable ()
 886                 {
 887                         if (namespace_using_table != null)
 888                                 return namespace_using_table;
 889
 890                         if (using_clauses == null) {
 891                                 namespace_using_table = empty_namespaces;
 892                                 return namespace_using_table;
 893                         }
 894
 895                         ArrayList list = new ArrayList (using_clauses.Count);
 896
 897                         foreach (UsingEntry ue in using_clauses) {
 898                                 Namespace using_ns = ue.Resolve ();
 899                                 if (using_ns == null)
 900                                         continue;
 901
 902                                 list.Add (using_ns);
 903                         }
 904
 905                         namespace_using_table = new Namespace [list.Count];
 906                         list.CopyTo (namespace_using_table, 0);
 907                         return namespace_using_table;
 908                 }
 909
 910                 readonly string [] empty_using_list = new string [0];
 911
 912                 public int SymbolFileID {
 913                         get {
 914                                 if (symfile_id == 0 && file.SourceFileEntry != null) {
 915                                         int parent_id = parent == null ? 0 : parent.SymbolFileID;
 916
 917                                         string [] using_list = empty_using_list;
 918                                         if (using_clauses != null) {
 919                                                 using_list = new string [using_clauses.Count];
 920                                                 for (int i = 0; i < using_clauses.Count; i++)
 921                                                         using_list [i] = ((UsingEntry) using_clauses [i]).Name.ToString ();
 922                                         }
 923
 924                                         symfile_id = CodeGen.SymbolWriter.DefineNamespace (ns.Name, file.SourceFileEntry, using_list, parent_id);
 925                                 }
 926                                 return symfile_id;
 927                         }
 928                 }
 929
 930                 static void MsgtryRef (string s)
 931                 {
 932                         Console.WriteLine ("    Try using -r:" + s);
 933                 }
 934
 935                 static void MsgtryPkg (string s)
 936                 {
 937                         Console.WriteLine ("    Try using -pkg:" + s);
 938                 }
 939
 940                 public static void Error_NamespaceNotFound (Location loc, string name)
 941                 {
 942                         Report.Error (246, loc, "The type or namespace name `{0}' could not be found. Are you missing a using directive or an assembly reference?",
 943                                 name);
 944
 945                         switch (name) {
 946                         case "Gtk": case "GtkSharp":
 947                                 MsgtryPkg ("gtk-sharp");
 948                                 break;
 949
 950                         case "Gdk": case "GdkSharp":
 951                                 MsgtryPkg ("gdk-sharp");
 952                                 break;
 953
 954                         case "Glade": case "GladeSharp":
 955                                 MsgtryPkg ("glade-sharp");
 956                                 break;
 957
 958                         case "System.Drawing":
 959                         case "System.Web.Services":
 960                         case "System.Web":
 961                         case "System.Data":
 962                         case "System.Windows.Forms":
 963                                 MsgtryRef (name);
 964                                 break;
 965                         }
 966                 }
 967
 968                 /// <summary>
 969                 ///   Used to validate that all the using clauses are correct
 970                 ///   after we are finished parsing all the files.
 971                 /// </summary>
 972                 void VerifyUsing ()
 973                 {
 974                         if (extern_aliases != null) {
 975                                 foreach (DictionaryEntry de in extern_aliases)
 976                                         ((AliasEntry) de.Value).Resolve ();
 977                         }
 978
 979                         if (using_clauses != null) {
 980                                 foreach (UsingEntry ue in using_clauses)
 981                                         ue.Resolve ();
 982                         }
 983
 984                         if (aliases != null) {
 985                                 foreach (DictionaryEntry de in aliases)
 986                                         ((AliasEntry) de.Value).Resolve ();
 987                         }
 988                 }
 989
 990                 /// <summary>
 991                 ///   Used to validate that all the using clauses are correct
 992                 ///   after we are finished parsing all the files.
 993                 /// </summary>
 994                 static public void VerifyAllUsing ()
 995                 {
 996                         foreach (NamespaceEntry entry in entries)
 997                                 entry.VerifyUsing ();
 998                 }
 999
1000                 public string GetSignatureForError ()
1001                 {
1002                         return ns.GetSignatureForError ();
1003                 }
1004
1005                 public override string ToString ()
1006                 {
1007                         return ns.ToString ();
1008                 }
1009         }
1010 }