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