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 //
  11
  12 using System;
  13 using System.Collections;
  14 using System.Reflection.Emit;
  15
  16 namespace Mono.CSharp
  17 {
  18         //
  19         // Implemented by elements which can act as independent contexts
  20         // during resolve phase. Used mostly for lookups.
  21         //
  22         public interface IMemberContext
  23         {
  24                 //
  25                 // A scope type context, it can be inflated for generic types
  26                 //
  27                 Type CurrentType { get; }
  28
  29                 //
  30                 // A scope type parameters either VAR or MVAR
  31                 //
  32                 TypeParameter[] CurrentTypeParameters { get; }
  33
  34                 //
  35                 // A type definition of the type context. For partial types definition use
  36                 // CurrentTypeDefinition.PartialContainer otherwise the context is local
  37                 //
  38                 // TODO: CurrentType.Definition
  39                 //
  40                 TypeContainer CurrentTypeDefinition { get; }
  41
  42                 bool IsObsolete { get; }
  43                 bool IsUnsafe { get; }
  44                 bool IsStatic { get; }
  45
  46                 string GetSignatureForError ();
  47
  48                 ExtensionMethodGroupExpr LookupExtensionMethod (Type extensionType, string name, Location loc);
  49                 FullNamedExpression LookupNamespaceOrType (string name, Location loc, bool ignore_cs0104);
  50                 FullNamedExpression LookupNamespaceAlias (string name);
  51
  52                 CompilerContext Compiler { get; }
  53         }
  54
  55         //
  56         // Block or statement resolving context
  57         //
  58         public class BlockContext : ResolveContext
  59         {
  60                 FlowBranching current_flow_branching;
  61
  62                 public TypeInferenceContext ReturnTypeInference;
  63
  64                 Type return_type;
  65
  66                 /// <summary>
  67                 ///   The location where return has to jump to return the
  68                 ///   value
  69                 /// </summary>
  70                 public Label ReturnLabel;       // TODO: It's emit dependant
  71
  72                 /// <summary>
  73                 ///   If we already defined the ReturnLabel
  74                 /// </summary>
  75                 public bool HasReturnLabel;
  76
  77                 public BlockContext (IMemberContext mc, ExplicitBlock block, Type returnType)
  78                         : base (mc)
  79                 {
  80                         if (returnType == null)
  81                                 throw new ArgumentNullException ("returnType");
  82
  83                         this.return_type = returnType;
  84
  85                         // TODO: check for null value
  86                         CurrentBlock = block;
  87                 }
  88
  89                 public override FlowBranching CurrentBranching {
  90                         get { return current_flow_branching; }
  91                 }
  92
  93                 // <summary>
  94                 //   Starts a new code branching.  This inherits the state of all local
  95                 //   variables and parameters from the current branching.
  96                 // </summary>
  97                 public FlowBranching StartFlowBranching (FlowBranching.BranchingType type, Location loc)
  98                 {
  99                         current_flow_branching = FlowBranching.CreateBranching (CurrentBranching, type, null, loc);
 100                         return current_flow_branching;
 101                 }
 102
 103                 // <summary>
 104                 //   Starts a new code branching for block `block'.
 105                 // </summary>
 106                 public FlowBranching StartFlowBranching (Block block)
 107                 {
 108                         Set (Options.DoFlowAnalysis);
 109
 110                         current_flow_branching = FlowBranching.CreateBranching (
 111                                 CurrentBranching, FlowBranching.BranchingType.Block, block, block.StartLocation);
 112                         return current_flow_branching;
 113                 }
 114
 115                 public FlowBranchingTryCatch StartFlowBranching (TryCatch stmt)
 116                 {
 117                         FlowBranchingTryCatch branching = new FlowBranchingTryCatch (CurrentBranching, stmt);
 118                         current_flow_branching = branching;
 119                         return branching;
 120                 }
 121
 122                 public FlowBranchingException StartFlowBranching (ExceptionStatement stmt)
 123                 {
 124                         FlowBranchingException branching = new FlowBranchingException (CurrentBranching, stmt);
 125                         current_flow_branching = branching;
 126                         return branching;
 127                 }
 128
 129                 public FlowBranchingLabeled StartFlowBranching (LabeledStatement stmt)
 130                 {
 131                         FlowBranchingLabeled branching = new FlowBranchingLabeled (CurrentBranching, stmt);
 132                         current_flow_branching = branching;
 133                         return branching;
 134                 }
 135
 136                 public FlowBranchingIterator StartFlowBranching (Iterator iterator)
 137                 {
 138                         FlowBranchingIterator branching = new FlowBranchingIterator (CurrentBranching, iterator);
 139                         current_flow_branching = branching;
 140                         return branching;
 141                 }
 142
 143                 public FlowBranchingToplevel StartFlowBranching (ToplevelBlock stmt, FlowBranching parent)
 144                 {
 145                         FlowBranchingToplevel branching = new FlowBranchingToplevel (parent, stmt);
 146                         current_flow_branching = branching;
 147                         return branching;
 148                 }
 149
 150                 // <summary>
 151                 //   Ends a code branching.  Merges the state of locals and parameters
 152                 //   from all the children of the ending branching.
 153                 // </summary>
 154                 public bool EndFlowBranching ()
 155                 {
 156                         FlowBranching old = current_flow_branching;
 157                         current_flow_branching = current_flow_branching.Parent;
 158
 159                         FlowBranching.UsageVector vector = current_flow_branching.MergeChild (old);
 160                         return vector.IsUnreachable;
 161                 }
 162
 163                 // <summary>
 164                 //   Kills the current code branching.  This throws away any changed state
 165                 //   information and should only be used in case of an error.
 166                 // </summary>
 167                 // FIXME: this is evil
 168                 public void KillFlowBranching ()
 169                 {
 170                         current_flow_branching = current_flow_branching.Parent;
 171                 }
 172
 173                 //
 174                 // This method is used during the Resolution phase to flag the
 175                 // need to define the ReturnLabel
 176                 //
 177                 public void NeedReturnLabel ()
 178                 {
 179                         if (!HasReturnLabel)
 180                                 HasReturnLabel = true;
 181                 }
 182
 183                 public Type ReturnType {
 184                         get { return return_type; }
 185                 }
 186         }
 187
 188         //
 189         // Expression resolving context
 190         //
 191         public class ResolveContext : IMemberContext
 192         {
 193                 [Flags]
 194                 public enum Options
 195                 {
 196                         /// <summary>
 197                         ///   This flag tracks the `checked' state of the compilation,
 198                         ///   it controls whether we should generate code that does overflow
 199                         ///   checking, or if we generate code that ignores overflows.
 200                         ///
 201                         ///   The default setting comes from the command line option to generate
 202                         ///   checked or unchecked code plus any source code changes using the
 203                         ///   checked/unchecked statements or expressions.   Contrast this with
 204                         ///   the ConstantCheckState flag.
 205                         /// </summary>
 206                         CheckedScope = 1 << 0,
 207
 208                         /// <summary>
 209                         ///   The constant check state is always set to `true' and cant be changed
 210                         ///   from the command line.  The source code can change this setting with
 211                         ///   the `checked' and `unchecked' statements and expressions.
 212                         /// </summary>
 213                         ConstantCheckState = 1 << 1,
 214
 215                         AllCheckStateFlags = CheckedScope | ConstantCheckState,
 216
 217                         //
 218                         // unsafe { ... } scope
 219                         //
 220                         UnsafeScope = 1 << 2,
 221                         CatchScope = 1 << 3,
 222                         FinallyScope = 1 << 4,
 223                         FieldInitializerScope = 1 << 5,
 224                         CompoundAssignmentScope = 1 << 6,
 225                         FixedInitializerScope = 1 << 7,
 226                         BaseInitializer = 1 << 8,
 227
 228                         //
 229                         // Inside an enum definition, we do not resolve enumeration values
 230                         // to their enumerations, but rather to the underlying type/value
 231                         // This is so EnumVal + EnumValB can be evaluated.
 232                         //
 233                         // There is no "E operator + (E x, E y)", so during an enum evaluation
 234                         // we relax the rules
 235                         //
 236                         EnumScope = 1 << 9,
 237
 238                         ConstantScope = 1 << 10,
 239
 240                         ConstructorScope = 1 << 11,
 241
 242                         /// <summary>
 243                         ///   Whether control flow analysis is enabled
 244                         /// </summary>
 245                         DoFlowAnalysis = 1 << 20,
 246
 247                         /// <summary>
 248                         ///   Whether control flow analysis is disabled on structs
 249                         ///   (only meaningful when DoFlowAnalysis is set)
 250                         /// </summary>
 251                         OmitStructFlowAnalysis = 1 << 21,
 252
 253                         ///
 254                         /// Indicates the current context is in probing mode, no errors are reported.
 255                         ///
 256                         ProbingMode = 1 << 22,
 257
 258                         //
 259                         // Return and ContextualReturn statements will set the ReturnType
 260                         // value based on the expression types of each return statement
 261                         // instead of the method return type which is initially null.
 262                         //
 263                         InferReturnType = 1 << 23,
 264
 265                         OmitDebuggingInfo = 1 << 24
 266                 }
 267
 268                 // utility helper for CheckExpr, UnCheckExpr, Checked and Unchecked statements
 269                 // it's public so that we can use a struct at the callsite
 270                 public struct FlagsHandle : IDisposable
 271                 {
 272                         ResolveContext ec;
 273                         readonly Options invmask, oldval;
 274
 275                         public FlagsHandle (ResolveContext ec, Options flagsToSet)
 276                                 : this (ec, flagsToSet, flagsToSet)
 277                         {
 278                         }
 279
 280                         internal FlagsHandle (ResolveContext ec, Options mask, Options val)
 281                         {
 282                                 this.ec = ec;
 283                                 invmask = ~mask;
 284                                 oldval = ec.flags & mask;
 285                                 ec.flags = (ec.flags & invmask) | (val & mask);
 286
 287 //                              if ((mask & Options.ProbingMode) != 0)
 288 //                                      ec.Report.DisableReporting ();
 289                         }
 290
 291                         public void Dispose ()
 292                         {
 293 //                              if ((invmask & Options.ProbingMode) == 0)
 294 //                                      ec.Report.EnableReporting ();
 295
 296                                 ec.flags = (ec.flags & invmask) | oldval;
 297                         }
 298                 }
 299
 300                 Options flags;
 301
 302                 //
 303                 // Whether we are inside an anonymous method.
 304                 //
 305                 public AnonymousExpression CurrentAnonymousMethod;
 306
 307                 //
 308                 // Holds a varible used during collection or object initialization.
 309                 //
 310                 public Expression CurrentInitializerVariable;
 311
 312                 public Block CurrentBlock;
 313
 314                 public IMemberContext MemberContext;
 315
 316                 /// <summary>
 317                 ///   If this is non-null, points to the current switch statement
 318                 /// </summary>
 319                 public Switch Switch;
 320
 321                 public ResolveContext (IMemberContext mc)
 322                 {
 323                         MemberContext = mc;
 324
 325                         //
 326                         // The default setting comes from the command line option
 327                         //
 328                         if (RootContext.Checked)
 329                                 flags |= Options.CheckedScope;
 330
 331                         //
 332                         // The constant check state is always set to true
 333                         //
 334                         flags |= Options.ConstantCheckState;
 335                 }
 336
 337                 public ResolveContext (IMemberContext mc, Options options)
 338                         : this (mc)
 339                 {
 340                         flags |= options;
 341                 }
 342
 343                 public CompilerContext Compiler {
 344                         get { return MemberContext.Compiler; }
 345                 }
 346
 347                 public virtual FlowBranching CurrentBranching {
 348                         get { return null; }
 349                 }
 350
 351                 //
 352                 // The current iterator
 353                 //
 354                 public Iterator CurrentIterator {
 355                         get { return CurrentAnonymousMethod as Iterator; }
 356                 }
 357
 358                 public Type CurrentType {
 359                         get { return MemberContext.CurrentType; }
 360                 }
 361
 362                 public TypeParameter[] CurrentTypeParameters {
 363                         get { return MemberContext.CurrentTypeParameters; }
 364                 }
 365
 366                 public TypeContainer CurrentTypeDefinition {
 367                         get { return MemberContext.CurrentTypeDefinition; }
 368                 }
 369
 370                 public bool ConstantCheckState {
 371                         get { return (flags & Options.ConstantCheckState) != 0; }
 372                 }
 373
 374                 public bool DoFlowAnalysis {
 375                         get { return (flags & Options.DoFlowAnalysis) != 0; }
 376                 }
 377
 378                 public bool IsInProbingMode {
 379                         get { return (flags & Options.ProbingMode) != 0; }
 380                 }
 381
 382                 public bool IsVariableCapturingRequired {
 383                         get {
 384                                 return !IsInProbingMode && (CurrentBranching == null || !CurrentBranching.CurrentUsageVector.IsUnreachable);
 385                         }
 386                 }
 387
 388                 public bool OmitStructFlowAnalysis {
 389                         get { return (flags & Options.OmitStructFlowAnalysis) != 0; }
 390                 }
 391
 392                 // TODO: Merge with CompilerGeneratedThis
 393                 public Expression GetThis (Location loc)
 394                 {
 395                         This my_this;
 396                         if (CurrentBlock != null)
 397                                 my_this = new This (CurrentBlock, loc);
 398                         else
 399                                 my_this = new This (loc);
 400
 401                         if (!my_this.ResolveBase (this))
 402                                 my_this = null;
 403
 404                         return my_this;
 405                 }
 406
 407                 public bool MustCaptureVariable (LocalInfo local)
 408                 {
 409                         if (CurrentAnonymousMethod == null)
 410                                 return false;
 411
 412                         // FIXME: IsIterator is too aggressive, we should capture only if child
 413                         // block contains yield
 414                         if (CurrentAnonymousMethod.IsIterator)
 415                                 return true;
 416
 417                         return local.Block.Toplevel != CurrentBlock.Toplevel;
 418                 }
 419
 420                 public bool HasSet (Options options)
 421                 {
 422                         return (this.flags & options) == options;
 423                 }
 424
 425                 public bool HasAny (Options options)
 426                 {
 427                         return (this.flags & options) != 0;
 428                 }
 429
 430                 public Report Report {
 431                         get {
 432                                 return Compiler.Report;
 433                         }
 434                 }
 435
 436                 // Temporarily set all the given flags to the given value.  Should be used in an 'using' statement
 437                 public FlagsHandle Set (Options options)
 438                 {
 439                         return new FlagsHandle (this, options);
 440                 }
 441
 442                 public FlagsHandle With (Options options, bool enable)
 443                 {
 444                         return new FlagsHandle (this, options, enable ? options : 0);
 445                 }
 446
 447                 public FlagsHandle WithFlowAnalysis (bool do_flow_analysis, bool omit_struct_analysis)
 448                 {
 449                         Options newflags =
 450                                 (do_flow_analysis ? Options.DoFlowAnalysis : 0) |
 451                                 (omit_struct_analysis ? Options.OmitStructFlowAnalysis : 0);
 452                         return new FlagsHandle (this, Options.DoFlowAnalysis | Options.OmitStructFlowAnalysis, newflags);
 453                 }
 454
 455                 #region IMemberContext Members
 456
 457                 public string GetSignatureForError ()
 458                 {
 459                         return MemberContext.GetSignatureForError ();
 460                 }
 461
 462                 public bool IsObsolete {
 463                         get {
 464                                 // Disables obsolete checks when probing is on
 465                                 return IsInProbingMode || MemberContext.IsObsolete;
 466                         }
 467                 }
 468
 469                 public bool IsStatic {
 470                         get { return MemberContext.IsStatic; }
 471                 }
 472
 473                 public bool IsUnsafe {
 474                         get { return HasSet (Options.UnsafeScope) || MemberContext.IsUnsafe; }
 475                 }
 476
 477                 public ExtensionMethodGroupExpr LookupExtensionMethod (Type extensionType, string name, Location loc)
 478                 {
 479                         return MemberContext.LookupExtensionMethod (extensionType, name, loc);
 480                 }
 481
 482                 public FullNamedExpression LookupNamespaceOrType (string name, Location loc, bool ignore_cs0104)
 483                 {
 484                         return MemberContext.LookupNamespaceOrType (name, loc, ignore_cs0104);
 485                 }
 486
 487                 public FullNamedExpression LookupNamespaceAlias (string name)
 488                 {
 489                         return MemberContext.LookupNamespaceAlias (name);
 490                 }
 491
 492                 #endregion
 493         }
 494
 495         //
 496         // This class is used during the Statement.Clone operation
 497         // to remap objects that have been cloned.
 498         //
 499         // Since blocks are cloned by Block.Clone, we need a way for
 500         // expressions that must reference the block to be cloned
 501         // pointing to the new cloned block.
 502         //
 503         public class CloneContext
 504         {
 505                 Hashtable block_map = new Hashtable ();
 506                 Hashtable variable_map;
 507
 508                 public void AddBlockMap (Block from, Block to)
 509                 {
 510                         if (block_map.Contains (from))
 511                                 return;
 512                         block_map[from] = to;
 513                 }
 514
 515                 public Block LookupBlock (Block from)
 516                 {
 517                         Block result = (Block) block_map[from];
 518
 519                         if (result == null) {
 520                                 result = (Block) from.Clone (this);
 521                                 block_map[from] = result;
 522                         }
 523
 524                         return result;
 525                 }
 526
 527                 ///
 528                 /// Remaps block to cloned copy if one exists.
 529                 ///
 530                 public Block RemapBlockCopy (Block from)
 531                 {
 532                         Block mapped_to = (Block) block_map[from];
 533                         if (mapped_to == null)
 534                                 return from;
 535
 536                         return mapped_to;
 537                 }
 538
 539                 public void AddVariableMap (LocalInfo from, LocalInfo to)
 540                 {
 541                         if (variable_map == null)
 542                                 variable_map = new Hashtable ();
 543
 544                         if (variable_map.Contains (from))
 545                                 return;
 546                         variable_map[from] = to;
 547                 }
 548
 549                 public LocalInfo LookupVariable (LocalInfo from)
 550                 {
 551                         LocalInfo result = (LocalInfo) variable_map[from];
 552
 553                         if (result == null)
 554                                 throw new Exception ("LookupVariable: looking up a variable that has not been registered yet");
 555
 556                         return result;
 557                 }
 558         }
 559
 560         //
 561         // Main compiler context
 562         //
 563         public class CompilerContext
 564         {
 565                 readonly Report report;
 566
 567                 public CompilerContext (Report report)
 568                 {
 569                         this.report = report;
 570                 }
 571
 572                 public Report Report {
 573                         get { return report; }
 574                 }
 575
 576                 //public PredefinedAttributes PredefinedAttributes {
 577                 //    get { throw new NotImplementedException (); }
 578                 //}
 579         }
 580
 581         //
 582         // Generic code emitter context
 583         //
 584         public class BuilderContext
 585         {
 586                 [Flags]
 587                 public enum Options
 588                 {
 589                         /// <summary>
 590                         ///   This flag tracks the `checked' state of the compilation,
 591                         ///   it controls whether we should generate code that does overflow
 592                         ///   checking, or if we generate code that ignores overflows.
 593                         ///
 594                         ///   The default setting comes from the command line option to generate
 595                         ///   checked or unchecked code plus any source code changes using the
 596                         ///   checked/unchecked statements or expressions.   Contrast this with
 597                         ///   the ConstantCheckState flag.
 598                         /// </summary>
 599                         CheckedScope = 1 << 0,
 600
 601                         /// <summary>
 602                         ///   The constant check state is always set to `true' and cant be changed
 603                         ///   from the command line.  The source code can change this setting with
 604                         ///   the `checked' and `unchecked' statements and expressions.
 605                         /// </summary>
 606                         ConstantCheckState = 1 << 1,
 607
 608                         AllCheckStateFlags = CheckedScope | ConstantCheckState,
 609
 610                         OmitDebugInfo = 1 << 2,
 611
 612                         ConstructorScope = 1 << 3
 613                 }
 614
 615                 // utility helper for CheckExpr, UnCheckExpr, Checked and Unchecked statements
 616                 // it's public so that we can use a struct at the callsite
 617                 public struct FlagsHandle : IDisposable
 618                 {
 619                         BuilderContext ec;
 620                         readonly Options invmask, oldval;
 621
 622                         public FlagsHandle (BuilderContext ec, Options flagsToSet)
 623                                 : this (ec, flagsToSet, flagsToSet)
 624                         {
 625                         }
 626
 627                         internal FlagsHandle (BuilderContext ec, Options mask, Options val)
 628                         {
 629                                 this.ec = ec;
 630                                 invmask = ~mask;
 631                                 oldval = ec.flags & mask;
 632                                 ec.flags = (ec.flags & invmask) | (val & mask);
 633                         }
 634
 635                         public void Dispose ()
 636                         {
 637                                 ec.flags = (ec.flags & invmask) | oldval;
 638                         }
 639                 }
 640
 641                 Options flags;
 642
 643                 public bool HasSet (Options options)
 644                 {
 645                         return (this.flags & options) == options;
 646                 }
 647
 648                 // Temporarily set all the given flags to the given value.  Should be used in an 'using' statement
 649                 public FlagsHandle With (Options options, bool enable)
 650                 {
 651                         return new FlagsHandle (this, options, enable ? options : 0);
 652                 }
 653         }
 654 }