mcs/mcs/context.cs

   1 //
   2 // context.cs: Various compiler contexts.
   3 //
   4 // Author:
   5 //   Marek Safar (marek.safar@gmail.com)
   6 //   Miguel de Icaza (miguel@ximian.com)
   7 //
   8 // Copyright 2001, 2002, 2003 Ximian, Inc.
   9 // Copyright 2004-2009 Novell, Inc.
  10 // Copyright 2011 Xamarin Inc.
  11 //
  12
  13 using System;
  14 using System.Collections.Generic;
  15 using System.IO;
  16 using System.Security.Cryptography;
  17 using System.Diagnostics;
  18
  19 namespace Mono.CSharp
  20 {
  21         public enum LookupMode
  22         {
  23                 Normal = 0,
  24                 Probing = 1,
  25                 IgnoreAccessibility = 2,
  26                 IgnoreStaticUsing = 1 << 10
  27         }
  28
  29         //
  30         // Implemented by elements which can act as independent contexts
  31         // during resolve phase. Used mostly for lookups.
  32         //
  33         public interface IMemberContext : IModuleContext
  34         {
  35                 //
  36                 // A scope type context, it can be inflated for generic types
  37                 //
  38                 TypeSpec CurrentType { get; }
  39
  40                 //
  41                 // A scope type parameters either VAR or MVAR
  42                 //
  43                 TypeParameters CurrentTypeParameters { get; }
  44
  45                 //
  46                 // A member definition of the context. For partial types definition use
  47                 // CurrentTypeDefinition.PartialContainer otherwise the context is local
  48                 //
  49                 // TODO: Obsolete it in this context, dynamic context cannot guarantee sensible value
  50                 //
  51                 MemberCore CurrentMemberDefinition { get; }
  52
  53                 bool IsObsolete { get; }
  54                 bool IsUnsafe { get; }
  55                 bool IsStatic { get; }
  56
  57                 string GetSignatureForError ();
  58
  59                 ExtensionMethodCandidates LookupExtensionMethod (string name, int arity);
  60                 FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc);
  61                 FullNamedExpression LookupNamespaceAlias (string name);
  62         }
  63
  64         public interface IModuleContext
  65         {
  66                 ModuleContainer Module { get; }
  67         }
  68
  69         //
  70         // Block or statement resolving context
  71         //
  72         public class BlockContext : ResolveContext
  73         {
  74                 readonly TypeSpec return_type;
  75
  76                 //
  77                 // Tracks the last offset used by VariableInfo
  78                 //
  79                 public int AssignmentInfoOffset;
  80
  81                 public BlockContext (IMemberContext mc, ExplicitBlock block, TypeSpec returnType)
  82                         : base (mc)
  83                 {
  84                         if (returnType == null)
  85                                 throw new ArgumentNullException ("returnType");
  86
  87                         this.return_type = returnType;
  88
  89                         // TODO: check for null value
  90                         CurrentBlock = block;
  91                 }
  92
  93                 public BlockContext (ResolveContext rc, ExplicitBlock block, TypeSpec returnType)
  94                         : this (rc.MemberContext, block, returnType)
  95                 {
  96                         if (rc.IsUnsafe)
  97                                 flags |= ResolveContext.Options.UnsafeScope;
  98
  99                         if (rc.HasSet (ResolveContext.Options.CheckedScope))
 100                                 flags |= ResolveContext.Options.CheckedScope;
 101
 102                         if (!rc.ConstantCheckState)
 103                                 flags &= ~Options.ConstantCheckState;
 104
 105                         if (rc.IsInProbingMode)
 106                                 flags |= ResolveContext.Options.ProbingMode;
 107
 108                         if (rc.HasSet (ResolveContext.Options.FieldInitializerScope))
 109                                 flags |= ResolveContext.Options.FieldInitializerScope;
 110
 111                         if (rc.HasSet (ResolveContext.Options.ExpressionTreeConversion))
 112                                 flags |= ResolveContext.Options.ExpressionTreeConversion;
 113
 114                         if (rc.HasSet (ResolveContext.Options.BaseInitializer))
 115                                 flags |= ResolveContext.Options.BaseInitializer;
 116
 117                         if (rc.HasSet (ResolveContext.Options.QueryClauseScope))
 118                                 flags |= ResolveContext.Options.QueryClauseScope;
 119                 }
 120
 121                 public ExceptionStatement CurrentTryBlock { get; set; }
 122
 123                 public TryCatch CurrentTryCatch { get; set; }
 124
 125                 public LoopStatement EnclosingLoop { get; set; }
 126
 127                 public LoopStatement EnclosingLoopOrSwitch { get; set; }
 128
 129                 public Switch Switch { get; set; }
 130
 131                 public TypeSpec ReturnType {
 132                         get { return return_type; }
 133                 }
 134         }
 135
 136         //
 137         // Expression resolving context
 138         //
 139         public class ResolveContext : IMemberContext
 140         {
 141                 [Flags]
 142                 public enum Options
 143                 {
 144                         /// <summary>
 145                         ///   This flag tracks the `checked' state of the compilation,
 146                         ///   it controls whether we should generate code that does overflow
 147                         ///   checking, or if we generate code that ignores overflows.
 148                         ///
 149                         ///   The default setting comes from the command line option to generate
 150                         ///   checked or unchecked code plus any source code changes using the
 151                         ///   checked/unchecked statements or expressions.   Contrast this with
 152                         ///   the ConstantCheckState flag.
 153                         /// </summary>
 154                         CheckedScope = 1 << 0,
 155
 156                         /// <summary>
 157                         ///   The constant check state is always set to `true' and cant be changed
 158                         ///   from the command line.  The source code can change this setting with
 159                         ///   the `checked' and `unchecked' statements and expressions.
 160                         /// </summary>
 161                         ConstantCheckState = 1 << 1,
 162
 163                         AllCheckStateFlags = CheckedScope | ConstantCheckState,
 164
 165                         //
 166                         // unsafe { ... } scope
 167                         //
 168                         UnsafeScope = 1 << 2,
 169                         CatchScope = 1 << 3,
 170                         FinallyScope = 1 << 4,
 171                         FieldInitializerScope = 1 << 5,
 172                         CompoundAssignmentScope = 1 << 6,
 173                         FixedInitializerScope = 1 << 7,
 174                         BaseInitializer = 1 << 8,
 175
 176                         //
 177                         // Inside an enum definition, we do not resolve enumeration values
 178                         // to their enumerations, but rather to the underlying type/value
 179                         // This is so EnumVal + EnumValB can be evaluated.
 180                         //
 181                         // There is no "E operator + (E x, E y)", so during an enum evaluation
 182                         // we relax the rules
 183                         //
 184                         EnumScope = 1 << 9,
 185
 186                         ConstantScope = 1 << 10,
 187
 188                         ConstructorScope = 1 << 11,
 189
 190                         UsingInitializerScope = 1 << 12,
 191
 192                         LockScope = 1 << 13,
 193
 194                         TryScope = 1 << 14,
 195
 196                         TryWithCatchScope = 1 << 15,
 197
 198                         DontSetConditionalAccessReceiver = 1 << 16,
 199
 200                         NameOfScope = 1 << 17,
 201
 202                         QueryClauseScope = 1 << 18,
 203
 204                         ///
 205                         /// Indicates the current context is in probing mode, no errors are reported.
 206                         ///
 207                         ProbingMode = 1 << 22,
 208
 209                         //
 210                         // Return and ContextualReturn statements will set the ReturnType
 211                         // value based on the expression types of each return statement
 212                         // instead of the method return type which is initially null.
 213                         //
 214                         InferReturnType = 1 << 23,
 215
 216                         OmitDebuggingInfo = 1 << 24,
 217
 218                         ExpressionTreeConversion = 1 << 25,
 219
 220                         InvokeSpecialName = 1 << 26
 221                 }
 222
 223                 // utility helper for CheckExpr, UnCheckExpr, Checked and Unchecked statements
 224                 // it's public so that we can use a struct at the callsite
 225                 public struct FlagsHandle : IDisposable
 226                 {
 227                         readonly ResolveContext ec;
 228                         readonly Options invmask, oldval;
 229
 230                         public FlagsHandle (ResolveContext ec, Options flagsToSet)
 231                                 : this (ec, flagsToSet, flagsToSet)
 232                         {
 233                         }
 234
 235                         internal FlagsHandle (ResolveContext ec, Options mask, Options val)
 236                         {
 237                                 this.ec = ec;
 238                                 invmask = ~mask;
 239                                 oldval = ec.flags & mask;
 240                                 ec.flags = (ec.flags & invmask) | (val & mask);
 241
 242 //                              if ((mask & Options.ProbingMode) != 0)
 243 //                                      ec.Report.DisableReporting ();
 244                         }
 245
 246                         public void Dispose ()
 247                         {
 248 //                              if ((invmask & Options.ProbingMode) == 0)
 249 //                                      ec.Report.EnableReporting ();
 250
 251                                 ec.flags = (ec.flags & invmask) | oldval;
 252                         }
 253                 }
 254
 255                 protected Options flags;
 256
 257                 //
 258                 // Whether we are inside an anonymous method.
 259                 //
 260                 public AnonymousExpression CurrentAnonymousMethod;
 261
 262                 //
 263                 // Holds a varible used during collection or object initialization.
 264                 //
 265                 public Expression CurrentInitializerVariable;
 266
 267                 public Block CurrentBlock;
 268
 269                 public readonly IMemberContext MemberContext;
 270
 271                 public ResolveContext (IMemberContext mc)
 272                 {
 273                         if (mc == null)
 274                                 throw new ArgumentNullException ();
 275
 276                         MemberContext = mc;
 277
 278                         //
 279                         // The default setting comes from the command line option
 280                         //
 281                         if (mc.Module.Compiler.Settings.Checked)
 282                                 flags |= Options.CheckedScope;
 283
 284                         //
 285                         // The constant check state is always set to true
 286                         //
 287                         flags |= Options.ConstantCheckState;
 288                 }
 289
 290                 public ResolveContext (IMemberContext mc, Options options)
 291                         : this (mc)
 292                 {
 293                         flags |= options;
 294                 }
 295
 296                 #region Properties
 297
 298                 public BuiltinTypes BuiltinTypes {
 299                         get {
 300                                 return MemberContext.Module.Compiler.BuiltinTypes;
 301                         }
 302                 }
 303
 304                 public virtual ExplicitBlock ConstructorBlock {
 305                         get {
 306                                 return CurrentBlock.Explicit;
 307                         }
 308                 }
 309
 310                 //
 311                 // The current iterator
 312                 //
 313                 public Iterator CurrentIterator {
 314                         get { return CurrentAnonymousMethod as Iterator; }
 315                 }
 316
 317                 public TypeSpec CurrentType {
 318                         get { return MemberContext.CurrentType; }
 319                 }
 320
 321                 public TypeParameters CurrentTypeParameters {
 322                         get { return MemberContext.CurrentTypeParameters; }
 323                 }
 324
 325                 public MemberCore CurrentMemberDefinition {
 326                         get { return MemberContext.CurrentMemberDefinition; }
 327                 }
 328
 329                 public bool ConstantCheckState {
 330                         get { return (flags & Options.ConstantCheckState) != 0; }
 331                 }
 332
 333                 public bool IsInProbingMode {
 334                         get {
 335                                 return (flags & Options.ProbingMode) != 0;
 336                         }
 337                 }
 338
 339                 public bool IsObsolete {
 340                         get {
 341                                 // Disables obsolete checks when probing is on
 342                                 return MemberContext.IsObsolete;
 343                         }
 344                 }
 345
 346                 public bool IsStatic {
 347                         get {
 348                                 return MemberContext.IsStatic;
 349                         }
 350                 }
 351
 352                 public bool IsUnsafe {
 353                         get {
 354                                 return HasSet (Options.UnsafeScope) || MemberContext.IsUnsafe;
 355                         }
 356                 }
 357
 358                 public bool IsRuntimeBinder {
 359                         get {
 360                                 return Module.Compiler.IsRuntimeBinder;
 361                         }
 362                 }
 363
 364                 public bool IsVariableCapturingRequired {
 365                         get {
 366                                 return !IsInProbingMode;
 367                         }
 368                 }
 369
 370                 public ModuleContainer Module {
 371                         get {
 372                                 return MemberContext.Module;
 373                         }
 374                 }
 375
 376                 public Report Report {
 377                         get {
 378                                 return Module.Compiler.Report;
 379                         }
 380                 }
 381
 382                 #endregion
 383
 384                 public bool MustCaptureVariable (INamedBlockVariable local)
 385                 {
 386                         if (CurrentAnonymousMethod == null)
 387                                 return false;
 388
 389                         //
 390                         // Capture only if this or any of child blocks contain yield
 391                         // or it's a parameter
 392                         //
 393                         if (CurrentAnonymousMethod.IsIterator)
 394                                 return local.IsParameter || local.Block.Explicit.HasYield;
 395
 396                         //
 397                         // Capture only if this or any of child blocks contain await
 398                         // or it's a parameter or we need to access variable from
 399                         // different parameter block
 400                         //
 401                         if (CurrentAnonymousMethod is AsyncInitializer)
 402                                 return local.IsParameter || local.Block.Explicit.HasAwait || CurrentBlock.Explicit.HasAwait ||
 403                                         local.Block.ParametersBlock != CurrentBlock.ParametersBlock.Original;
 404
 405                         return local.Block.ParametersBlock != CurrentBlock.ParametersBlock.Original;
 406                 }
 407
 408                 public bool HasSet (Options options)
 409                 {
 410                         return (this.flags & options) == options;
 411                 }
 412
 413                 public bool HasAny (Options options)
 414                 {
 415                         return (this.flags & options) != 0;
 416                 }
 417
 418
 419                 // Temporarily set all the given flags to the given value.  Should be used in an 'using' statement
 420                 public FlagsHandle Set (Options options)
 421                 {
 422                         return new FlagsHandle (this, options);
 423                 }
 424
 425                 public FlagsHandle With (Options options, bool enable)
 426                 {
 427                         return new FlagsHandle (this, options, enable ? options : 0);
 428                 }
 429
 430                 #region IMemberContext Members
 431
 432                 public string GetSignatureForError ()
 433                 {
 434                         return MemberContext.GetSignatureForError ();
 435                 }
 436
 437                 public ExtensionMethodCandidates LookupExtensionMethod (string name, int arity)
 438                 {
 439                         return MemberContext.LookupExtensionMethod (name, arity);
 440                 }
 441
 442                 public FullNamedExpression LookupNamespaceOrType (string name, int arity, LookupMode mode, Location loc)
 443                 {
 444                         return MemberContext.LookupNamespaceOrType (name, arity, mode, loc);
 445                 }
 446
 447                 public FullNamedExpression LookupNamespaceAlias (string name)
 448                 {
 449                         return MemberContext.LookupNamespaceAlias (name);
 450                 }
 451
 452                 #endregion
 453         }
 454
 455         public class FlowAnalysisContext
 456         {
 457                 readonly CompilerContext ctx;
 458
 459                 public FlowAnalysisContext (CompilerContext ctx, ParametersBlock parametersBlock, int definiteAssignmentLength)
 460                 {
 461                         this.ctx = ctx;
 462                         this.ParametersBlock = parametersBlock;
 463
 464                         DefiniteAssignment = definiteAssignmentLength == 0 ?
 465                                 DefiniteAssignmentBitSet.Empty :
 466                                 new DefiniteAssignmentBitSet (definiteAssignmentLength);
 467                 }
 468
 469                 public DefiniteAssignmentBitSet DefiniteAssignment { get; set; }
 470
 471                 public DefiniteAssignmentBitSet DefiniteAssignmentOnTrue { get; set; }
 472
 473                 public DefiniteAssignmentBitSet DefiniteAssignmentOnFalse { get; set; }
 474
 475                 Dictionary<Statement, List<DefiniteAssignmentBitSet>> LabelStack { get; set; }
 476
 477                 public ParametersBlock ParametersBlock { get; set; }
 478
 479                 public Report Report {
 480                         get {
 481                                 return ctx.Report;
 482                         }
 483                 }
 484
 485                 public DefiniteAssignmentBitSet SwitchInitialDefinitiveAssignment { get; set; }
 486
 487                 public TryFinally TryFinally { get; set; }
 488
 489                 public bool UnreachableReported { get; set; }
 490
 491                 public bool AddReachedLabel (Statement label)
 492                 {
 493                         List<DefiniteAssignmentBitSet> das;
 494                         if (LabelStack == null) {
 495                                 LabelStack = new Dictionary<Statement, List<DefiniteAssignmentBitSet>> ();
 496                                 das = null;
 497                         } else {
 498                                 LabelStack.TryGetValue (label, out das);
 499                         }
 500
 501                         if (das == null) {
 502                                 das = new List<DefiniteAssignmentBitSet> ();
 503                                 das.Add (new DefiniteAssignmentBitSet (DefiniteAssignment));
 504                                 LabelStack.Add (label, das);
 505                                 return false;
 506                         }
 507
 508                         foreach (var existing in das) {
 509                                 if (DefiniteAssignmentBitSet.IsIncluded (existing, DefiniteAssignment))
 510                                         return true;
 511                         }
 512
 513                         if (DefiniteAssignment == DefiniteAssignmentBitSet.Empty)
 514                                 das.Add (DefiniteAssignment);
 515                         else
 516                                 das.Add (new DefiniteAssignmentBitSet (DefiniteAssignment));
 517
 518                         return false;
 519                 }
 520
 521                 public DefiniteAssignmentBitSet BranchDefiniteAssignment ()
 522                 {
 523                         return BranchDefiniteAssignment (DefiniteAssignment);
 524                 }
 525
 526                 public DefiniteAssignmentBitSet BranchDefiniteAssignment (DefiniteAssignmentBitSet da)
 527                 {
 528                         if (da != DefiniteAssignmentBitSet.Empty) {
 529                                 DefiniteAssignment = new DefiniteAssignmentBitSet (da);
 530                         }
 531
 532                         return da;
 533                 }
 534
 535                 public Dictionary<Statement, List<DefiniteAssignmentBitSet>> CopyLabelStack ()
 536                 {
 537                         if (LabelStack == null)
 538                                 return null;
 539
 540                         var dest = new Dictionary<Statement, List<DefiniteAssignmentBitSet>> ();
 541                         foreach (var entry in LabelStack) {
 542                                 dest.Add (entry.Key, new List<DefiniteAssignmentBitSet> (entry.Value));
 543                         }
 544
 545                         return dest;
 546                 }
 547
 548                 public bool IsDefinitelyAssigned (VariableInfo variable)
 549                 {
 550                         return variable.IsAssigned (DefiniteAssignment);
 551                 }
 552
 553                 public bool IsStructFieldDefinitelyAssigned (VariableInfo variable, string name)
 554                 {
 555                         return variable.IsStructFieldAssigned (DefiniteAssignment, name);
 556                 }
 557
 558                 public void SetLabelStack (Dictionary<Statement, List<DefiniteAssignmentBitSet>> labelStack)
 559                 {
 560                         LabelStack = labelStack;
 561                 }
 562
 563                 public void SetVariableAssigned (VariableInfo variable, bool generatedAssignment = false)
 564                 {
 565                         variable.SetAssigned (DefiniteAssignment, generatedAssignment);
 566                 }
 567
 568                 public void SetVariableAssigned (VariableInfo variable, DefiniteAssignmentBitSet da)
 569                 {
 570                         variable.SetAssigned (da, false);
 571                 }
 572
 573                 public void SetStructFieldAssigned (VariableInfo variable, string name)
 574                 {
 575                         variable.SetStructFieldAssigned (DefiniteAssignment, name);
 576                 }
 577         }
 578
 579
 580         //
 581         // This class is used during the Statement.Clone operation
 582         // to remap objects that have been cloned.
 583         //
 584         // Since blocks are cloned by Block.Clone, we need a way for
 585         // expressions that must reference the block to be cloned
 586         // pointing to the new cloned block.
 587         //
 588         public class CloneContext
 589         {
 590                 Dictionary<Block, Block> block_map = new Dictionary<Block, Block> ();
 591
 592                 public void AddBlockMap (Block from, Block to)
 593                 {
 594                         block_map.Add (from, to);
 595                 }
 596
 597                 public Block LookupBlock (Block from)
 598                 {
 599                         Block result;
 600                         if (!block_map.TryGetValue (from, out result)) {
 601                                 result = (Block) from.Clone (this);
 602                         }
 603
 604                         return result;
 605                 }
 606
 607                 ///
 608                 /// Remaps block to cloned copy if one exists.
 609                 ///
 610                 public Block RemapBlockCopy (Block from)
 611                 {
 612                         Block mapped_to;
 613                         if (!block_map.TryGetValue (from, out mapped_to))
 614                                 return from;
 615
 616                         return mapped_to;
 617                 }
 618         }
 619
 620         //
 621         // Main compiler context
 622         //
 623         public class CompilerContext
 624         {
 625                 static readonly TimeReporter DisabledTimeReporter = new TimeReporter (false);
 626
 627                 readonly Report report;
 628                 readonly BuiltinTypes builtin_types;
 629                 readonly CompilerSettings settings;
 630
 631                 Dictionary<string, SourceFile> all_source_files;
 632
 633                 public CompilerContext (CompilerSettings settings, ReportPrinter reportPrinter)
 634                 {
 635                         this.settings = settings;
 636                         this.report = new Report (this, reportPrinter);
 637                         this.builtin_types = new BuiltinTypes ();
 638                         this.TimeReporter = DisabledTimeReporter;
 639                 }
 640
 641                 #region Properties
 642
 643                 public BuiltinTypes BuiltinTypes {
 644                         get {
 645                                 return builtin_types;
 646                         }
 647                 }
 648
 649                 // Used for special handling of runtime dynamic context mostly
 650                 // by error reporting but also by member accessibility checks
 651                 public bool IsRuntimeBinder {
 652                         get; set;
 653                 }
 654
 655                 public Report Report {
 656                         get {
 657                                 return report;
 658                         }
 659                 }
 660
 661                 public CompilerSettings Settings {
 662                         get {
 663                                 return settings;
 664                         }
 665                 }
 666
 667                 public List<SourceFile> SourceFiles {
 668                         get {
 669                                 return settings.SourceFiles;
 670                         }
 671                 }
 672
 673                 internal TimeReporter TimeReporter {
 674                         get; set;
 675                 }
 676
 677                 #endregion
 678
 679                 //
 680                 // This is used when we encounter a #line preprocessing directive during parsing
 681                 // to register additional source file names
 682                 //
 683                 public SourceFile LookupFile (CompilationSourceFile comp_unit, string name)
 684                 {
 685                         if (all_source_files == null) {
 686                                 all_source_files = new Dictionary<string, SourceFile> ();
 687                                 foreach (var source in SourceFiles)
 688                                         all_source_files[source.OriginalFullPathName] = source;
 689                         }
 690
 691                         string path;
 692                         if (!Path.IsPathRooted (name)) {
 693                                 var loc = comp_unit.SourceFile;
 694                                 string root = Path.GetDirectoryName (loc.OriginalFullPathName);
 695                                 path = Path.GetFullPath (Path.Combine (root, name));
 696                                 var dir = Path.GetDirectoryName (loc.Name);
 697                                 if (!string.IsNullOrEmpty (dir))
 698                                         name = Path.Combine (dir, name);
 699                         } else
 700                                 path = name;
 701
 702                         SourceFile retval;
 703                         if (all_source_files.TryGetValue (path, out retval))
 704                                 return retval;
 705
 706                         retval = new SourceFile (name, path, all_source_files.Count + 1);
 707                         Location.AddFile (retval);
 708                         all_source_files.Add (path, retval);
 709                         return retval;
 710                 }
 711         }
 712
 713         //
 714         // Generic code emitter context
 715         //
 716         public class BuilderContext
 717         {
 718                 [Flags]
 719                 public enum Options
 720                 {
 721                         /// <summary>
 722                         ///   This flag tracks the `checked' state of the compilation,
 723                         ///   it controls whether we should generate code that does overflow
 724                         ///   checking, or if we generate code that ignores overflows.
 725                         ///
 726                         ///   The default setting comes from the command line option to generate
 727                         ///   checked or unchecked code plus any source code changes using the
 728                         ///   checked/unchecked statements or expressions.   Contrast this with
 729                         ///   the ConstantCheckState flag.
 730                         /// </summary>
 731                         CheckedScope = 1 << 0,
 732
 733                         AccurateDebugInfo = 1 << 1,
 734
 735                         OmitDebugInfo = 1 << 2,
 736
 737                         ConstructorScope = 1 << 3,
 738
 739                         AsyncBody = 1 << 4,
 740                 }
 741
 742                 // utility helper for CheckExpr, UnCheckExpr, Checked and Unchecked statements
 743                 // it's public so that we can use a struct at the callsite
 744                 public struct FlagsHandle : IDisposable
 745                 {
 746                         readonly BuilderContext ec;
 747                         readonly Options invmask, oldval;
 748
 749                         public FlagsHandle (BuilderContext ec, Options flagsToSet)
 750                                 : this (ec, flagsToSet, flagsToSet)
 751                         {
 752                         }
 753
 754                         internal FlagsHandle (BuilderContext ec, Options mask, Options val)
 755                         {
 756                                 this.ec = ec;
 757                                 invmask = ~mask;
 758                                 oldval = ec.flags & mask;
 759                                 ec.flags = (ec.flags & invmask) | (val & mask);
 760                         }
 761
 762                         public void Dispose ()
 763                         {
 764                                 ec.flags = (ec.flags & invmask) | oldval;
 765                         }
 766                 }
 767
 768                 protected Options flags;
 769
 770                 public bool HasSet (Options options)
 771                 {
 772                         return (this.flags & options) == options;
 773                 }
 774
 775                 // Temporarily set all the given flags to the given value.  Should be used in an 'using' statement
 776                 public FlagsHandle With (Options options, bool enable)
 777                 {
 778                         return new FlagsHandle (this, options, enable ? options : 0);
 779                 }
 780         }
 781
 782         //
 783         // Parser session objects. We could recreate all these objects for each parser
 784         // instance but the best parser performance the session object can be reused
 785         //
 786         public class ParserSession
 787         {
 788                 MD5 md5;
 789
 790                 public readonly char[] StreamReaderBuffer = new char[SeekableStreamReader.DefaultReadAheadSize * 2];
 791                 public readonly Dictionary<char[], string>[] Identifiers = new Dictionary<char[], string>[Tokenizer.MaxIdentifierLength + 1];
 792                 public readonly List<Parameter> ParametersStack = new List<Parameter> (4);
 793                 public readonly char[] IDBuilder = new char[Tokenizer.MaxIdentifierLength];
 794                 public readonly char[] NumberBuilder = new char[Tokenizer.MaxNumberLength];
 795
 796                 public LocationsBag LocationsBag { get; set; }
 797                 public bool UseJayGlobalArrays { get; set; }
 798                 public LocatedToken[] LocatedTokens { get; set; }
 799
 800                 public MD5 GetChecksumAlgorithm ()
 801                 {
 802                         return md5 ?? (md5 = MD5.Create ());
 803                 }
 804         }
 805 }