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 RegisterNamespace (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                                         RegisterNamespace (ns);
 100                                 return;
 101                         }
 102
 103                         foreach (Type t in assembly.GetExportedTypes ())
 104                                 RegisterNamespace (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                                 RegisterNamespace (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 (found_type);
 229                                         if (loc.IsNull) {
 230                                                 DeclSpace ds = TypeManager.LookupDeclSpace (t);
 231                                                 Report.Warning (1685, 1, ds.Location, "The type `{0}' conflicts with the predefined type `{1}' and will be ignored",
 232                                                         ds.GetSignatureForError (), TypeManager.CSharpName (found_type));
 233                                                 return found_type;
 234                                         }
 235                                         Report.SymbolRelatedToPreviousError (t);
 236                                         Report.Warning (436, 2, loc, "The type `{0}' conflicts with the imported type `{1}'. Ignoring the imported type definition",
 237                                                 TypeManager.CSharpName (t), TypeManager.CSharpName (found_type));
 238                                         return t;
 239                                 }
 240                         }
 241
 242                         return found_type;
 243                 }
 244         }
 245
 246         /// <summary>
 247         ///   Keeps track of the namespaces defined in the C# code.
 248         ///
 249         ///   This is an Expression to allow it to be referenced in the
 250         ///   compiler parse/intermediate tree during name resolution.
 251         /// </summary>
 252         public class Namespace : FullNamedExpression {
 253
 254                 Namespace parent;
 255                 string fullname;
 256                 IDictionary namespaces;
 257                 IDictionary declspaces;
 258                 Hashtable cached_types;
 259                 RootNamespace root;
 260
 261                 public readonly MemberName MemberName;
 262
 263                 /// <summary>
 264                 ///   Constructor Takes the current namespace and the
 265                 ///   name.  This is bootstrapped with parent == null
 266                 ///   and name = ""
 267                 /// </summary>
 268                 public Namespace (Namespace parent, string name)
 269                 {
 270                         // Expression members.
 271                         this.eclass = ExprClass.Namespace;
 272                         this.Type = typeof (Namespace);
 273                         this.loc = Location.Null;
 274
 275                         this.parent = parent;
 276
 277                         if (parent != null)
 278                                 this.root = parent.root;
 279                         else
 280                                 this.root = this as RootNamespace;
 281
 282                         if (this.root == null)
 283                                 throw new InternalErrorException ("Root namespaces must be created using RootNamespace");
 284
 285                         string pname = parent != null ? parent.Name : "";
 286
 287                         if (pname == "")
 288                                 fullname = name;
 289                         else
 290                                 fullname = parent.Name + "." + name;
 291
 292                         if (fullname == null)
 293                                 throw new InternalErrorException ("Namespace has a null fullname");
 294
 295                         if (parent != null && parent.MemberName != MemberName.Null)
 296                                 MemberName = new MemberName (parent.MemberName, name);
 297                         else if (name.Length == 0)
 298                                 MemberName = MemberName.Null;
 299                         else
 300                                 MemberName = new MemberName (name);
 301
 302                         namespaces = new HybridDictionary ();
 303                         cached_types = new Hashtable ();
 304
 305                         root.RegisterNamespace (this);
 306                 }
 307
 308                 public override Expression DoResolve (EmitContext ec)
 309                 {
 310                         return this;
 311                 }
 312
 313                 public virtual void Error_NamespaceDoesNotExist (DeclSpace ds, Location loc, string name)
 314                 {
 315                         if (name.IndexOf ('`') > 0) {
 316                                 FullNamedExpression retval = Lookup (ds, SimpleName.RemoveGenericArity (name), loc);
 317                                 if (retval != null) {
 318                                         Error_TypeArgumentsCannotBeUsed (retval.Type, loc, "type");
 319                                         return;
 320                                 }
 321                         } else {
 322                                 Type t = LookForAnyGenericType (name);
 323                                 if (t != null) {
 324                                         Error_InvalidNumberOfTypeArguments (t, loc);
 325                                         return;
 326                                 }
 327                         }
 328
 329                         Report.Error (234, loc, "The type or namespace name `{0}' does not exist in the namespace `{1}'. Are you missing an assembly reference?",
 330                                 name, FullName);
 331                 }
 332
 333                 public static void Error_InvalidNumberOfTypeArguments (Type t, Location loc)
 334                 {
 335                         Report.SymbolRelatedToPreviousError (t);
 336                         Report.Error (305, loc, "Using the generic type `{0}' requires `{1}' type argument(s)",
 337                                 TypeManager.CSharpName(t), TypeManager.GetNumberOfTypeArguments(t).ToString());
 338                 }
 339
 340                 public static void Error_TypeArgumentsCannotBeUsed(Type t, Location loc, string symbol)
 341                 {
 342                         Report.SymbolRelatedToPreviousError(t);
 343                         Report.Error(308, loc, "The non-generic {0} `{1}' cannot be used with the type argument(s)",
 344                                 symbol, TypeManager.CSharpName(t));
 345                 }
 346
 347                 public override void Emit (EmitContext ec)
 348                 {
 349                         throw new InternalErrorException ("Expression tree referenced namespace " + fullname + " during Emit ()");
 350                 }
 351
 352                 public override string GetSignatureForError ()
 353                 {
 354                         return Name;
 355                 }
 356
 357                 public Namespace GetNamespace (string name, bool create)
 358                 {
 359                         int pos = name.IndexOf ('.');
 360
 361                         Namespace ns;
 362                         string first;
 363                         if (pos >= 0)
 364                                 first = name.Substring (0, pos);
 365                         else
 366                                 first = name;
 367
 368                         ns = (Namespace) namespaces [first];
 369                         if (ns == null) {
 370                                 if (!create)
 371                                         return null;
 372
 373                                 ns = new Namespace (this, first);
 374                                 namespaces.Add (first, ns);
 375                         }
 376
 377                         if (pos >= 0)
 378                                 ns = ns.GetNamespace (name.Substring (pos + 1), create);
 379
 380                         return ns;
 381                 }
 382
 383                 TypeExpr LookupType (string name, Location loc)
 384                 {
 385                         if (cached_types.Contains (name))
 386                                 return cached_types [name] as TypeExpr;
 387
 388                         Type t = null;
 389                         if (declspaces != null) {
 390                                 DeclSpace tdecl = declspaces [name] as DeclSpace;
 391                                 if (tdecl != null) {
 392                                         //
 393                                         // Note that this is not:
 394                                         //
 395                                         //   t = tdecl.DefineType ()
 396                                         //
 397                                         // This is to make it somewhat more useful when a DefineType
 398                                         // fails due to problems in nested types (more useful in the sense
 399                                         // of fewer misleading error messages)
 400                                         //
 401                                         tdecl.DefineType ();
 402                                         t = tdecl.TypeBuilder;
 403                                 }
 404                         }
 405                         string lookup = t != null ? t.FullName : (fullname.Length == 0 ? name : fullname + "." + name);
 406                         Type rt = root.LookupTypeReflection (lookup, loc);
 407
 408                         // HACK: loc.IsNull when the type is core type
 409                         if (t == null || (rt != null && loc.IsNull))
 410                                 t = rt;
 411
 412                         TypeExpr te = t == null ? null : new TypeExpression (t, Location.Null);
 413                         cached_types [name] = te;
 414                         return te;
 415                 }
 416
 417                 ///
 418                 /// Used for better error reporting only
 419                 ///
 420                 public Type LookForAnyGenericType (string typeName)
 421                 {
 422                         if (declspaces == null)
 423                                 return null;
 424
 425                         typeName = SimpleName.RemoveGenericArity (typeName);
 426
 427                         foreach (DictionaryEntry de in declspaces) {
 428                                 string type_item = (string) de.Key;
 429                                 int pos = type_item.LastIndexOf ('`');
 430                                 if (pos == typeName.Length && String.Compare (typeName, 0, type_item, 0, pos) == 0)
 431                                         return ((DeclSpace) de.Value).TypeBuilder;
 432                         }
 433                         return null;
 434                 }
 435
 436                 public FullNamedExpression Lookup (DeclSpace ds, string name, Location loc)
 437                 {
 438                         if (namespaces.Contains (name))
 439                                 return (Namespace) namespaces [name];
 440
 441                         TypeExpr te = LookupType (name, loc);
 442                         if (te == null || !ds.CheckAccessLevel (te.Type))
 443                                 return null;
 444
 445                         return te;
 446                 }
 447
 448                 public void AddDeclSpace (string name, DeclSpace ds)
 449                 {
 450                         if (declspaces == null)
 451                                 declspaces = new HybridDictionary ();
 452                         declspaces.Add (name, ds);
 453                 }
 454
 455                 /// <summary>
 456                 ///   The qualified name of the current namespace
 457                 /// </summary>
 458                 public string Name {
 459                         get { return fullname; }
 460                 }
 461
 462                 public override string FullName {
 463                         get { return fullname; }
 464                 }
 465
 466                 /// <summary>
 467                 ///   The parent of this namespace, used by the parser to "Pop"
 468                 ///   the current namespace declaration
 469                 /// </summary>
 470                 public Namespace Parent {
 471                         get { return parent; }
 472                 }
 473
 474                 public override string ToString ()
 475                 {
 476                         return String.Format ("Namespace ({0})", Name);
 477                 }
 478         }
 479
 480         public class NamespaceEntry {
 481                 Namespace ns;
 482                 NamespaceEntry parent, implicit_parent;
 483                 SourceFile file;
 484                 int symfile_id;
 485                 Hashtable aliases;
 486                 ArrayList using_clauses;
 487                 public bool DeclarationFound = false;
 488                 bool UsingFound;
 489
 490                 public readonly DeclSpace SlaveDeclSpace;
 491
 492                 ListDictionary extern_aliases;
 493
 494                 static ArrayList entries = new ArrayList ();
 495
 496                 public static void Reset ()
 497                 {
 498                         entries = new ArrayList ();
 499                 }
 500
 501                 //
 502                 // This class holds the location where a using definition is
 503                 // done, and whether it has been used by the program or not.
 504                 //
 505                 // We use this to flag using clauses for namespaces that do not
 506                 // exist.
 507                 //
 508                 public class UsingEntry : IResolveContext {
 509                         public readonly MemberName Name;
 510                         readonly NamespaceEntry NamespaceEntry;
 511                         readonly Location Location;
 512
 513                         public UsingEntry (NamespaceEntry entry, MemberName name, Location loc)
 514                         {
 515                                 Name = name;
 516                                 NamespaceEntry = entry;
 517                                 Location = loc;
 518                         }
 519
 520                         internal Namespace resolved;
 521
 522                         public Namespace Resolve ()
 523                         {
 524                                 if (resolved != null)
 525                                         return resolved;
 526
 527                                 FullNamedExpression fne = Name.GetTypeExpression ().ResolveAsTypeStep (this, false);
 528                                 if (fne == null) {
 529                                         Error_NamespaceNotFound (Location, Name.ToString ());
 530                                         return null;
 531                                 }
 532
 533                                 resolved = fne as Namespace;
 534                                 if (resolved == null) {
 535                                         Report.SymbolRelatedToPreviousError (fne.Type);
 536                                         Report.Error (138, Location,
 537                                                 "`{0}' is a type not a namespace. A using namespace directive can only be applied to namespaces", Name.ToString ());
 538                                 }
 539                                 return resolved;
 540                         }
 541
 542                         DeclSpace IResolveContext.DeclContainer {
 543                                 get { return NamespaceEntry.SlaveDeclSpace; }
 544                         }
 545
 546                         DeclSpace IResolveContext.GenericDeclContainer {
 547                                 get { return NamespaceEntry.SlaveDeclSpace; }
 548                         }
 549
 550                         bool IResolveContext.IsInObsoleteScope {
 551                                 get { return false; }
 552                         }
 553                         bool IResolveContext.IsInUnsafeScope {
 554                                 get { return false; }
 555                         }
 556                 }
 557
 558                 public abstract class AliasEntry {
 559                         public readonly string Name;
 560                         public readonly NamespaceEntry NamespaceEntry;
 561                         public readonly Location Location;
 562
 563                         protected AliasEntry (NamespaceEntry entry, string name, Location loc)
 564                         {
 565                                 Name = name;
 566                                 NamespaceEntry = entry;
 567                                 Location = loc;
 568                         }
 569
 570                         protected FullNamedExpression resolved;
 571                         bool error;
 572
 573                         public FullNamedExpression Resolve ()
 574                         {
 575                                 if (resolved != null || error)
 576                                         return resolved;
 577                                 resolved = DoResolve ();
 578                                 if (resolved == null)
 579                                         error = true;
 580                                 return resolved;
 581                         }
 582
 583                         protected abstract FullNamedExpression DoResolve ();
 584                 }
 585
 586                 public class LocalAliasEntry : AliasEntry, IResolveContext {
 587                         public readonly Expression Alias;
 588
 589                         public LocalAliasEntry (NamespaceEntry entry, string name, MemberName alias, Location loc) :
 590                                 base (entry, name, loc)
 591                         {
 592                                 Alias = alias.GetTypeExpression ();
 593                         }
 594
 595                         protected override FullNamedExpression DoResolve ()
 596                         {
 597                                 resolved = Alias.ResolveAsTypeStep (this, false);
 598                                 if (resolved == null)
 599                                         return null;
 600
 601                                 if (resolved.Type != null) {
 602                                         TypeAttributes attr = resolved.Type.Attributes & TypeAttributes.VisibilityMask;
 603                                         if (attr == TypeAttributes.NestedPrivate || attr == TypeAttributes.NestedFamily ||
 604                                                 ((attr == TypeAttributes.NestedFamORAssem || attr == TypeAttributes.NestedAssembly) &&
 605                                                 TypeManager.LookupDeclSpace (resolved.Type) == null)) {
 606                                                 Expression.ErrorIsInaccesible (Alias.Location, Alias.ToString ());
 607                                                 return null;
 608                                         }
 609                                 }
 610
 611                                 return resolved;
 612                         }
 613
 614                         DeclSpace IResolveContext.DeclContainer {
 615                                 get { return NamespaceEntry.SlaveDeclSpace; }
 616                         }
 617
 618                         DeclSpace IResolveContext.GenericDeclContainer {
 619                                 get { return NamespaceEntry.SlaveDeclSpace; }
 620                         }
 621
 622                         bool IResolveContext.IsInObsoleteScope {
 623                                 get { return false; }
 624                         }
 625                         bool IResolveContext.IsInUnsafeScope {
 626                                 get { return false; }
 627                         }
 628                 }
 629
 630                 public class ExternAliasEntry : AliasEntry {
 631                         public ExternAliasEntry (NamespaceEntry entry, string name, Location loc) :
 632                                 base (entry, name, loc)
 633                         {
 634                         }
 635
 636                         protected override FullNamedExpression DoResolve ()
 637                         {
 638                                 resolved = RootNamespace.GetRootNamespace (Name);
 639                                 if (resolved == null)
 640                                         Report.Error (430, Location, "The extern alias '" + Name +
 641                                                                         "' was not specified in a /reference option");
 642
 643                                 return resolved;
 644                         }
 645                 }
 646
 647                 public NamespaceEntry (NamespaceEntry parent, SourceFile file, string name)
 648                 {
 649                         this.parent = parent;
 650                         this.file = file;
 651                         entries.Add (this);
 652                         this.ID = entries.Count;
 653
 654                         if (parent != null)
 655                                 ns = parent.NS.GetNamespace (name, true);
 656                         else if (name != null)
 657                                 ns = RootNamespace.Global.GetNamespace (name, true);
 658                         else
 659                                 ns = RootNamespace.Global;
 660                         SlaveDeclSpace = new RootDeclSpace (this);
 661                 }
 662
 663                 private NamespaceEntry (NamespaceEntry parent, SourceFile file, Namespace ns, bool slave)
 664                 {
 665                         this.parent = parent;
 666                         this.file = file;
 667                         // no need to add self to 'entries', since we don't have any aliases or using entries.
 668                         this.ID = -1;
 669                         this.IsImplicit = true;
 670                         this.ns = ns;
 671                         this.SlaveDeclSpace = slave ? new RootDeclSpace (this) : null;
 672                 }
 673
 674                 //
 675                 // According to section 16.3.1 (using-alias-directive), the namespace-or-type-name is
 676                 // resolved as if the immediately containing namespace body has no using-directives.
 677                 //
 678                 // Section 16.3.2 says that the same rule is applied when resolving the namespace-name
 679                 // in the using-namespace-directive.
 680                 //
 681                 // To implement these rules, the expressions in the using directives are resolved using
 682                 // the "doppelganger" (ghostly bodiless duplicate).
 683                 //
 684                 NamespaceEntry doppelganger;
 685                 NamespaceEntry Doppelganger {
 686                         get {
 687                                 if (!IsImplicit && doppelganger == null)
 688                                         doppelganger = new NamespaceEntry (ImplicitParent, file, ns, true);
 689                                 return doppelganger;
 690                         }
 691                 }
 692
 693                 public readonly int ID;
 694                 public readonly bool IsImplicit;
 695
 696                 public Namespace NS {
 697                         get { return ns; }
 698                 }
 699
 700                 public NamespaceEntry Parent {
 701                         get { return parent; }
 702                 }
 703
 704                 public NamespaceEntry ImplicitParent {
 705                         get {
 706                                 if (parent == null)
 707                                         return null;
 708                                 if (implicit_parent == null) {
 709                                         implicit_parent = (parent.NS == ns.Parent)
 710                                                 ? parent
 711                                                 : new NamespaceEntry (parent, file, ns.Parent, false);
 712                                 }
 713                                 return implicit_parent;
 714                         }
 715                 }
 716
 717                 /// <summary>
 718                 ///   Records a new namespace for resolving name references
 719                 /// </summary>
 720                 public void Using (MemberName name, Location loc)
 721                 {
 722                         if (DeclarationFound){
 723                                 Report.Error (1529, loc, "A using clause must precede all other namespace elements except extern alias declarations");
 724                                 return;
 725                         }
 726
 727                         UsingFound = true;
 728
 729                         if (name.Equals (ns.MemberName))
 730                                 return;
 731
 732                         if (using_clauses == null)
 733                                 using_clauses = new ArrayList ();
 734
 735                         foreach (UsingEntry old_entry in using_clauses) {
 736                                 if (name.Equals (old_entry.Name)) {
 737                                         Report.Warning (105, 3, loc, "The using directive for `{0}' appeared previously in this namespace", name.GetName ());
 738                                         return;
 739                                 }
 740                         }
 741
 742                         UsingEntry ue = new UsingEntry (Doppelganger, name, loc);
 743                         using_clauses.Add (ue);
 744                 }
 745
 746                 public void UsingAlias (string name, MemberName alias, Location loc)
 747                 {
 748                         if (DeclarationFound){
 749                                 Report.Error (1529, loc, "A using clause must precede all other namespace elements except extern alias declarations");
 750                                 return;
 751                         }
 752
 753                         UsingFound = true;
 754
 755                         if (aliases == null)
 756                                 aliases = new Hashtable ();
 757
 758                         if (aliases.Contains (name)) {
 759                                 AliasEntry ae = (AliasEntry) aliases [name];
 760                                 Report.SymbolRelatedToPreviousError (ae.Location, ae.Name);
 761                                 Report.Error (1537, loc, "The using alias `{0}' appeared previously in this namespace", name);
 762                                 return;
 763                         }
 764
 765                         if (RootContext.Version == LanguageVersion.Default &&
 766                             name == "global" && RootContext.WarningLevel >= 2)
 767                                 Report.Warning (440, 2, loc, "An alias named `global' will not be used when resolving 'global::';" +
 768                                         " the global namespace will be used instead");
 769
 770                         // FIXME: get correct error number.  See if the above check can be merged
 771                         if (extern_aliases != null && extern_aliases.Contains (name)) {
 772                                 AliasEntry ae = (AliasEntry) extern_aliases [name];
 773                                 Report.SymbolRelatedToPreviousError (ae.Location, ae.Name);
 774                                 Report.Error (1537, loc, "The using alias `{0}' appeared previously in this namespace", name);
 775                                 return;
 776                         }
 777
 778                         aliases [name] = new LocalAliasEntry (Doppelganger, name, alias, loc);
 779                 }
 780
 781                 public void UsingExternalAlias (string name, Location loc)
 782                 {
 783                         if (UsingFound || DeclarationFound) {
 784                                 Report.Error (439, loc, "An extern alias declaration must precede all other elements");
 785                                 return;
 786                         }
 787
 788                         // Share the extern_aliases field with the Doppelganger
 789                         if (extern_aliases == null) {
 790                                 extern_aliases = new ListDictionary ();
 791                                 Doppelganger.extern_aliases = extern_aliases;
 792                         }
 793
 794                         if (extern_aliases.Contains (name)) {
 795                                 AliasEntry ae = (AliasEntry) extern_aliases [name];
 796                                 Report.SymbolRelatedToPreviousError (ae.Location, ae.Name);
 797                                 Report.Error (1537, loc, "The using alias `{0}' appeared previously in this namespace", name);
 798                                 return;
 799                         }
 800
 801                         if (name == "global") {
 802                                 Report.Error (1681, loc, "You cannot redefine the global extern alias");
 803                                 return;
 804                         }
 805
 806                         // Register the alias in aliases and extern_aliases, since we need both of them
 807                         // to keep things simple (different resolution scenarios)
 808                         ExternAliasEntry alias = new ExternAliasEntry (Doppelganger, name, loc);
 809                         extern_aliases [name] = alias;
 810                 }
 811
 812                 public FullNamedExpression LookupNamespaceOrType (DeclSpace ds, string name, Location loc, bool ignore_cs0104)
 813                 {
 814                         // Precondition: Only simple names (no dots) will be looked up with this function.
 815                         FullNamedExpression resolved = null;
 816                         for (NamespaceEntry curr_ns = this; curr_ns != null; curr_ns = curr_ns.ImplicitParent) {
 817                                 if ((resolved = curr_ns.Lookup (ds, name, loc, ignore_cs0104)) != null)
 818                                         break;
 819                         }
 820                         return resolved;
 821                 }
 822
 823                 static void Error_AmbiguousTypeReference (Location loc, string name, FullNamedExpression t1, FullNamedExpression t2)
 824                 {
 825                         Report.Error (104, loc, "`{0}' is an ambiguous reference between `{1}' and `{2}'",
 826                                 name, t1.FullName, t2.FullName);
 827                 }
 828
 829                 // Looks-up a alias named @name in this and surrounding namespace declarations
 830                 public FullNamedExpression LookupAlias (string name)
 831                 {
 832                         AliasEntry entry = null;
 833                         for (NamespaceEntry n = this; n != null; n = n.ImplicitParent) {
 834                                 if (n.extern_aliases != null && (entry = n.extern_aliases [name] as AliasEntry) != null)
 835                                         break;
 836                                 if (n.aliases != null && (entry = n.aliases [name] as AliasEntry) != null)
 837                                         break;
 838                         }
 839                         return entry == null ? null : entry.Resolve ();
 840                 }
 841
 842                 private FullNamedExpression Lookup (DeclSpace ds, string name, Location loc, bool ignore_cs0104)
 843                 {
 844                         //
 845                         // Check whether it's in the namespace.
 846                         //
 847                         FullNamedExpression fne = ns.Lookup (ds, name, loc);
 848                         if (fne != null)
 849                                 return fne;
 850
 851                         if (extern_aliases != null) {
 852                                 AliasEntry entry = extern_aliases [name] as AliasEntry;
 853                                 if (entry != null)
 854                                         return entry.Resolve ();
 855                         }
 856
 857                         if (IsImplicit)
 858                                 return null;
 859
 860                         //
 861                         // Check aliases.
 862                         //
 863                         if (aliases != null) {
 864                                 AliasEntry entry = aliases [name] as AliasEntry;
 865                                 if (entry != null)
 866                                         return entry.Resolve ();
 867                         }
 868
 869                         //
 870                         // Check using entries.
 871                         //
 872                         FullNamedExpression match = null;
 873                         foreach (Namespace using_ns in GetUsingTable ()) {
 874                                 match = using_ns.Lookup (ds, name, loc);
 875                                 if (match == null || !(match is TypeExpr))
 876                                         continue;
 877                                 if (fne != null) {
 878                                         if (!ignore_cs0104)
 879                                                 Error_AmbiguousTypeReference (loc, name, fne, match);
 880                                         return null;
 881                                 }
 882                                 fne = match;
 883                         }
 884
 885                         return fne;
 886                 }
 887
 888                 // Our cached computation.
 889                 static readonly Namespace [] empty_namespaces = new Namespace [0];
 890                 Namespace [] namespace_using_table;
 891                 Namespace [] GetUsingTable ()
 892                 {
 893                         if (namespace_using_table != null)
 894                                 return namespace_using_table;
 895
 896                         if (using_clauses == null) {
 897                                 namespace_using_table = empty_namespaces;
 898                                 return namespace_using_table;
 899                         }
 900
 901                         ArrayList list = new ArrayList (using_clauses.Count);
 902
 903                         foreach (UsingEntry ue in using_clauses) {
 904                                 Namespace using_ns = ue.Resolve ();
 905                                 if (using_ns == null)
 906                                         continue;
 907
 908                                 list.Add (using_ns);
 909                         }
 910
 911                         namespace_using_table = new Namespace [list.Count];
 912                         list.CopyTo (namespace_using_table, 0);
 913                         return namespace_using_table;
 914                 }
 915
 916                 static readonly string [] empty_using_list = new string [0];
 917
 918                 public int SymbolFileID {
 919                         get {
 920                                 if (symfile_id == 0 && file.SourceFileEntry != null) {
 921                                         int parent_id = parent == null ? 0 : parent.SymbolFileID;
 922
 923                                         string [] using_list = empty_using_list;
 924                                         if (using_clauses != null) {
 925                                                 using_list = new string [using_clauses.Count];
 926                                                 for (int i = 0; i < using_clauses.Count; i++)
 927                                                         using_list [i] = ((UsingEntry) using_clauses [i]).Name.ToString ();
 928                                         }
 929
 930                                         symfile_id = CodeGen.SymbolWriter.DefineNamespace (ns.Name, file.SourceFileEntry, using_list, parent_id);
 931                                 }
 932                                 return symfile_id;
 933                         }
 934                 }
 935
 936                 static void MsgtryRef (string s)
 937                 {
 938                         Console.WriteLine ("    Try using -r:" + s);
 939                 }
 940
 941                 static void MsgtryPkg (string s)
 942                 {
 943                         Console.WriteLine ("    Try using -pkg:" + s);
 944                 }
 945
 946                 public static void Error_NamespaceNotFound (Location loc, string name)
 947                 {
 948                         Report.Error (246, loc, "The type or namespace name `{0}' could not be found. Are you missing a using directive or an assembly reference?",
 949                                 name);
 950
 951                         switch (name) {
 952                         case "Gtk": case "GtkSharp":
 953                                 MsgtryPkg ("gtk-sharp");
 954                                 break;
 955
 956                         case "Gdk": case "GdkSharp":
 957                                 MsgtryPkg ("gdk-sharp");
 958                                 break;
 959
 960                         case "Glade": case "GladeSharp":
 961                                 MsgtryPkg ("glade-sharp");
 962                                 break;
 963
 964                         case "System.Drawing":
 965                         case "System.Web.Services":
 966                         case "System.Web":
 967                         case "System.Data":
 968                         case "System.Windows.Forms":
 969                                 MsgtryRef (name);
 970                                 break;
 971                         }
 972                 }
 973
 974                 /// <summary>
 975                 ///   Used to validate that all the using clauses are correct
 976                 ///   after we are finished parsing all the files.
 977                 /// </summary>
 978                 void VerifyUsing ()
 979                 {
 980                         if (extern_aliases != null) {
 981                                 foreach (DictionaryEntry de in extern_aliases)
 982                                         ((AliasEntry) de.Value).Resolve ();
 983                         }
 984
 985                         if (using_clauses != null) {
 986                                 foreach (UsingEntry ue in using_clauses)
 987                                         ue.Resolve ();
 988                         }
 989
 990                         if (aliases != null) {
 991                                 foreach (DictionaryEntry de in aliases)
 992                                         ((AliasEntry) de.Value).Resolve ();
 993                         }
 994                 }
 995
 996                 /// <summary>
 997                 ///   Used to validate that all the using clauses are correct
 998                 ///   after we are finished parsing all the files.
 999                 /// </summary>
1000                 static public void VerifyAllUsing ()
1001                 {
1002                         foreach (NamespaceEntry entry in entries)
1003                                 entry.VerifyUsing ();
1004                 }
1005
1006                 public string GetSignatureForError ()
1007                 {
1008                         return ns.GetSignatureForError ();
1009                 }
1010
1011                 public override string ToString ()
1012                 {
1013                         return ns.ToString ();
1014                 }
1015         }
1016 }