mcs/mcs/eval.cs

   1 //
   2 // eval.cs: Evaluation and Hosting API for the C# compiler
   3 //
   4 // Authors:
   5 //   Miguel de Icaza (miguel@gnome.org)
   6 //   Marek Safar (marek.safar@gmail.com)
   7 //
   8 // Dual licensed under the terms of the MIT X11 or GNU GPL
   9 //
  10 // Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
  11 // Copyright 2004-2011 Novell, Inc
  12 // Copyright 2011 Xamarin Inc
  13 //
  14
  15 using System;
  16 using System.Threading;
  17 using System.Collections.Generic;
  18 using System.Reflection;
  19 using System.Reflection.Emit;
  20 using System.IO;
  21 using System.Text;
  22 using System.Linq;
  23
  24 namespace Mono.CSharp
  25 {
  26
  27         /// <summary>
  28         ///   Evaluator: provides an API to evaluate C# statements and
  29         ///   expressions dynamically.
  30         /// </summary>
  31         /// <remarks>
  32         ///   This class exposes static methods to evaluate expressions in the
  33         ///   current program.
  34         ///
  35         ///   To initialize the evaluator with a number of compiler
  36         ///   options call the Init(string[]args) method with a set of
  37         ///   command line options that the compiler recognizes.
  38         ///
  39         ///   To interrupt execution of a statement, you can invoke the
  40         ///   Evaluator.Interrupt method.
  41         /// </remarks>
  42         public class Evaluator {
  43
  44                 enum ParseMode {
  45                         // Parse silently, do not output any error messages
  46                         Silent,
  47
  48                         // Report errors during parse
  49                         ReportErrors,
  50
  51                         // Auto-complete, means that the tokenizer will start producing
  52                         // GETCOMPLETIONS tokens when it reaches a certain point.
  53                         GetCompletions
  54                 }
  55
  56                 static object evaluator_lock = new object ();
  57                 static volatile bool invoking;
  58
  59 #if !STATIC
  60                 static int count;
  61 #endif
  62                 static Thread invoke_thread;
  63
  64                 readonly Dictionary<string, Tuple<FieldSpec, FieldInfo>> fields;
  65
  66                 Type base_class;
  67                 bool inited;
  68                 int startup_files;
  69
  70                 readonly CompilerContext ctx;
  71                 readonly ModuleContainer module;
  72                 readonly ReflectionImporter importer;
  73                 readonly CompilationSourceFile source_file;
  74
  75                 public Evaluator (CompilerContext ctx)
  76                 {
  77                         this.ctx = ctx;
  78
  79                         module = new ModuleContainer (ctx);
  80                         module.Evaluator = this;
  81
  82                         source_file = new CompilationSourceFile (module, null);
  83                         module.AddTypeContainer (source_file);
  84
  85                         startup_files = ctx.SourceFiles.Count;
  86
  87                         // FIXME: Importer needs this assembly for internalsvisibleto
  88                         module.SetDeclaringAssembly (new AssemblyDefinitionDynamic (module, "evaluator"));
  89                         importer = new ReflectionImporter (module, ctx.BuiltinTypes);
  90
  91                         InteractiveBaseClass = typeof (InteractiveBase);
  92                         fields = new Dictionary<string, Tuple<FieldSpec, FieldInfo>> ();
  93                 }
  94
  95                 void Init ()
  96                 {
  97                         var loader = new DynamicLoader (importer, ctx);
  98
  99                         CompilerCallableEntryPoint.Reset ();
 100                         RootContext.ToplevelTypes = module;
 101
 102                         //var startup_files = new List<string> ();
 103                         //foreach (CompilationUnit file in Location.SourceFiles)
 104                         //    startup_files.Add (file.Path);
 105
 106                         loader.LoadReferences (module);
 107                         ctx.BuiltinTypes.CheckDefinitions (module);
 108                         module.InitializePredefinedTypes ();
 109
 110                         inited = true;
 111                 }
 112
 113                 void ParseStartupFiles ()
 114                 {
 115                         Driver d = new Driver (ctx);
 116
 117                         Location.Initialize (ctx.SourceFiles);
 118
 119                         var parser_session = new ParserSession ();
 120                         for (int i = 0; i < startup_files; ++i) {
 121                                 var sf = ctx.SourceFiles [i];
 122                                 d.Parse (sf, module, parser_session, ctx.Report);
 123                         }
 124                 }
 125
 126                 void Reset ()
 127                 {
 128                         CompilerCallableEntryPoint.PartialReset ();
 129
 130                         Location.Reset ();
 131                         Location.Initialize (ctx.SourceFiles);
 132                 }
 133
 134                 /// <summary>
 135                 ///   If true, turns type expressions into valid expressions
 136                 ///   and calls the describe method on it
 137                 /// </summary>
 138                 public bool DescribeTypeExpressions;
 139
 140                 /// <summary>
 141                 ///   Whether the evaluator will use terse syntax, and the semicolons at the end are optional
 142                 /// </summary>
 143                 public bool Terse = true;
 144
 145                 /// <summary>
 146                 ///   The base class for the classes that host the user generated code
 147                 /// </summary>
 148                 /// <remarks>
 149                 ///
 150                 ///   This is the base class that will host the code
 151                 ///   executed by the Evaluator.  By default
 152                 ///   this is the Mono.CSharp.InteractiveBase class
 153                 ///   which is useful for interactive use.
 154                 ///
 155                 ///   By changing this property you can control the
 156                 ///   base class and the static members that are
 157                 ///   available to your evaluated code.
 158                 /// </remarks>
 159                 public Type InteractiveBaseClass {
 160                         get {
 161                                 return base_class;
 162                         }
 163                         set {
 164                                 base_class = value;
 165
 166                                 if (value != null && typeof (InteractiveBase).IsAssignableFrom (value))
 167                                         InteractiveBase.Evaluator = this;
 168                         }
 169                 }
 170
 171                 /// <summary>
 172                 ///   Interrupts the evaluation of an expression executing in Evaluate.
 173                 /// </summary>
 174                 /// <remarks>
 175                 ///   Use this method to interrupt long-running invocations.
 176                 /// </remarks>
 177                 public void Interrupt ()
 178                 {
 179                         if (!inited || !invoking)
 180                                 return;
 181
 182                         if (invoke_thread != null)
 183                                 invoke_thread.Abort ();
 184                 }
 185
 186                 /// <summary>
 187                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 188                 /// </summary>
 189                 /// <remarks>
 190                 ///
 191                 ///   Compiles the input string as a C# expression or
 192                 ///   statement, unlike the Evaluate method, the
 193                 ///   resulting delegate can be invoked multiple times
 194                 ///   without incurring in the compilation overhead.
 195                 ///
 196                 ///   If the return value of this function is null,
 197                 ///   this indicates that the parsing was complete.
 198                 ///   If the return value is a string it indicates
 199                 ///   that the input string was partial and that the
 200                 ///   invoking code should provide more code before
 201                 ///   the code can be successfully compiled.
 202                 ///
 203                 ///   If you know that you will always get full expressions or
 204                 ///   statements and do not care about partial input, you can use
 205                 ///   the other Compile overload.
 206                 ///
 207                 ///   On success, in addition to returning null, the
 208                 ///   compiled parameter will be set to the delegate
 209                 ///   that can be invoked to execute the code.
 210                 ///
 211                 /// </remarks>
 212                 public string Compile (string input, out CompiledMethod compiled)
 213                 {
 214                         if (input == null || input.Length == 0){
 215                                 compiled = null;
 216                                 return null;
 217                         }
 218
 219                         lock (evaluator_lock){
 220                                 if (!inited) {
 221                                         Init ();
 222                                         ParseStartupFiles ();
 223                                 } else {
 224                                         ctx.Report.Printer.Reset ();
 225                                 }
 226
 227                                 bool partial_input;
 228                                 CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
 229
 230                                 // Terse mode, try to provide the trailing semicolon automatically.
 231                                 if (parser == null && Terse && partial_input){
 232                                         bool ignore;
 233
 234                                         // check if the source would compile with a block, if so, we should not
 235                                         // add the semicolon.
 236                                         var needs_block = ParseString (ParseMode.Silent, input + "{}", out ignore) != null;
 237                                         if (!needs_block)
 238                                                 parser = ParseString (ParseMode.Silent, input + ";", out ignore);
 239                                 }
 240                                 if (parser == null){
 241                                         compiled = null;
 242                                         if (partial_input)
 243                                                 return input;
 244
 245                                         ParseString (ParseMode.ReportErrors, input, out partial_input);
 246                                         return null;
 247                                 }
 248
 249                                 Class parser_result = parser.InteractiveResult;
 250                                 compiled = CompileBlock (parser_result, parser.undo, ctx.Report);
 251                                 return null;
 252                         }
 253                 }
 254
 255                 /// <summary>
 256                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 257                 /// </summary>
 258                 /// <remarks>
 259                 ///
 260                 ///   Compiles the input string as a C# expression or
 261                 ///   statement, unlike the Evaluate method, the
 262                 ///   resulting delegate can be invoked multiple times
 263                 ///   without incurring in the compilation overhead.
 264                 ///
 265                 ///   This method can only deal with fully formed input
 266                 ///   strings and does not provide a completion mechanism.
 267                 ///   If you must deal with partial input (for example for
 268                 ///   interactive use) use the other overload.
 269                 ///
 270                 ///   On success, a delegate is returned that can be used
 271                 ///   to invoke the method.
 272                 ///
 273                 /// </remarks>
 274                 public CompiledMethod Compile (string input)
 275                 {
 276                         CompiledMethod compiled;
 277
 278                         // Ignore partial inputs
 279                         if (Compile (input, out compiled) != null){
 280                                 // Error, the input was partial.
 281                                 return null;
 282                         }
 283
 284                         // Either null (on error) or the compiled method.
 285                         return compiled;
 286                 }
 287
 288                 /// <summary>
 289                 ///   Evaluates and expression or statement and returns any result values.
 290                 /// </summary>
 291                 /// <remarks>
 292                 ///   Evaluates the input string as a C# expression or
 293                 ///   statement.  If the input string is an expression
 294                 ///   the result will be stored in the result variable
 295                 ///   and the result_set variable will be set to true.
 296                 ///
 297                 ///   It is necessary to use the result/result_set
 298                 ///   pair to identify when a result was set (for
 299                 ///   example, execution of user-provided input can be
 300                 ///   an expression, a statement or others, and
 301                 ///   result_set would only be set if the input was an
 302                 ///   expression.
 303                 ///
 304                 ///   If the return value of this function is null,
 305                 ///   this indicates that the parsing was complete.
 306                 ///   If the return value is a string, it indicates
 307                 ///   that the input is partial and that the user
 308                 ///   should provide an updated string.
 309                 /// </remarks>
 310                 public string Evaluate (string input, out object result, out bool result_set)
 311                 {
 312                         CompiledMethod compiled;
 313
 314                         result_set = false;
 315                         result = null;
 316
 317                         input = Compile (input, out compiled);
 318                         if (input != null)
 319                                 return input;
 320
 321                         if (compiled == null)
 322                                 return null;
 323
 324                         //
 325                         // The code execution does not need to keep the compiler lock
 326                         //
 327                         object retval = typeof (QuitValue);
 328
 329                         try {
 330                                 invoke_thread = System.Threading.Thread.CurrentThread;
 331                                 invoking = true;
 332                                 compiled (ref retval);
 333                         } catch (ThreadAbortException e){
 334                                 Thread.ResetAbort ();
 335                                 Console.WriteLine ("Interrupted!\n{0}", e);
 336                         } finally {
 337                                 invoking = false;
 338                         }
 339
 340                         //
 341                         // We use a reference to a compiler type, in this case
 342                         // Driver as a flag to indicate that this was a statement
 343                         //
 344                         if (!ReferenceEquals (retval, typeof (QuitValue))) {
 345                                 result_set = true;
 346                                 result = retval;
 347                         }
 348
 349                         return null;
 350                 }
 351
 352                 public string [] GetCompletions (string input, out string prefix)
 353                 {
 354                         prefix = "";
 355                         if (input == null || input.Length == 0)
 356                                 return null;
 357
 358                         lock (evaluator_lock){
 359                                 if (!inited)
 360                                         Init ();
 361
 362                                 bool partial_input;
 363                                 CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
 364                                 if (parser == null){
 365                                         return null;
 366                                 }
 367
 368                                 Class parser_result = parser.InteractiveResult;
 369
 370 #if NET_4_0
 371                                 var access = AssemblyBuilderAccess.RunAndCollect;
 372 #else
 373                                 var access = AssemblyBuilderAccess.Run;
 374 #endif
 375                                 var a = new AssemblyDefinitionDynamic (module, "completions");
 376                                 a.Create (AppDomain.CurrentDomain, access);
 377                                 module.SetDeclaringAssembly (a);
 378
 379                                 // Need to setup MemberCache
 380                                 parser_result.CreateContainer ();
 381
 382                                 var method = parser_result.Members[0] as Method;
 383                                 BlockContext bc = new BlockContext (method, method.Block, ctx.BuiltinTypes.Void);
 384
 385                                 try {
 386                                         method.Block.Resolve (null, bc, method);
 387                                 } catch (CompletionResult cr) {
 388                                         prefix = cr.BaseText;
 389                                         return cr.Result;
 390                                 }
 391                         }
 392                         return null;
 393                 }
 394
 395                 /// <summary>
 396                 ///   Executes the given expression or statement.
 397                 /// </summary>
 398                 /// <remarks>
 399                 ///    Executes the provided statement, returns true
 400                 ///    on success, false on parsing errors.  Exceptions
 401                 ///    might be thrown by the called code.
 402                 /// </remarks>
 403                 public bool Run (string statement)
 404                 {
 405                         object result;
 406                         bool result_set;
 407
 408                         return Evaluate (statement, out result, out result_set) == null;
 409                 }
 410
 411                 /// <summary>
 412                 ///   Evaluates and expression or statement and returns the result.
 413                 /// </summary>
 414                 /// <remarks>
 415                 ///   Evaluates the input string as a C# expression or
 416                 ///   statement and returns the value.
 417                 ///
 418                 ///   This method will throw an exception if there is a syntax error,
 419                 ///   of if the provided input is not an expression but a statement.
 420                 /// </remarks>
 421                 public object Evaluate (string input)
 422                 {
 423                         object result;
 424                         bool result_set;
 425
 426                         string r = Evaluate (input, out result, out result_set);
 427
 428                         if (r != null)
 429                                 throw new ArgumentException ("Syntax error on input: partial input");
 430
 431                         if (result_set == false)
 432                                 throw new ArgumentException ("The expression did not set a result");
 433
 434                         return result;
 435                 }
 436
 437                 enum InputKind {
 438                         EOF,
 439                         StatementOrExpression,
 440                         CompilationUnit,
 441                         Error
 442                 }
 443
 444                 //
 445                 // Deambiguates the input string to determine if we
 446                 // want to process a statement or if we want to
 447                 // process a compilation unit.
 448                 //
 449                 // This is done using a top-down predictive parser,
 450                 // since the yacc/jay parser can not deambiguage this
 451                 // without more than one lookahead token.   There are very
 452                 // few ambiguities.
 453                 //
 454                 InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 455                 {
 456                         Tokenizer tokenizer = new Tokenizer (seekable, source_file, new ParserSession ());
 457
 458                         int t = tokenizer.token ();
 459                         switch (t){
 460                         case Token.EOF:
 461                                 return InputKind.EOF;
 462
 463                         // These are toplevels
 464                         case Token.EXTERN:
 465                         case Token.OPEN_BRACKET:
 466                         case Token.ABSTRACT:
 467                         case Token.CLASS:
 468                         case Token.ENUM:
 469                         case Token.INTERFACE:
 470                         case Token.INTERNAL:
 471                         case Token.NAMESPACE:
 472                         case Token.PRIVATE:
 473                         case Token.PROTECTED:
 474                         case Token.PUBLIC:
 475                         case Token.SEALED:
 476                         case Token.STATIC:
 477                         case Token.STRUCT:
 478                                 return InputKind.CompilationUnit;
 479
 480                         // Definitely expression
 481                         case Token.FIXED:
 482                         case Token.BOOL:
 483                         case Token.BYTE:
 484                         case Token.CHAR:
 485                         case Token.DECIMAL:
 486                         case Token.DOUBLE:
 487                         case Token.FLOAT:
 488                         case Token.INT:
 489                         case Token.LONG:
 490                         case Token.NEW:
 491                         case Token.OBJECT:
 492                         case Token.SBYTE:
 493                         case Token.SHORT:
 494                         case Token.STRING:
 495                         case Token.UINT:
 496                         case Token.ULONG:
 497                                 return InputKind.StatementOrExpression;
 498
 499                         // These need deambiguation help
 500                         case Token.USING:
 501                                 t = tokenizer.token ();
 502                                 if (t == Token.EOF)
 503                                         return InputKind.EOF;
 504
 505                                 if (t == Token.IDENTIFIER)
 506                                         return InputKind.CompilationUnit;
 507                                 return InputKind.StatementOrExpression;
 508
 509
 510                         // Distinguish between:
 511                         //    delegate opt_anonymous_method_signature block
 512                         //    delegate type
 513                         case Token.DELEGATE:
 514                                 t = tokenizer.token ();
 515                                 if (t == Token.EOF)
 516                                         return InputKind.EOF;
 517                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 518                                         return InputKind.StatementOrExpression;
 519                                 return InputKind.CompilationUnit;
 520
 521                         // Distinguih between:
 522                         //    unsafe block
 523                         //    unsafe as modifier of a type declaration
 524                         case Token.UNSAFE:
 525                                 t = tokenizer.token ();
 526                                 if (t == Token.EOF)
 527                                         return InputKind.EOF;
 528                                 if (t == Token.OPEN_PARENS)
 529                                         return InputKind.StatementOrExpression;
 530                                 return InputKind.CompilationUnit;
 531
 532                         // These are errors: we list explicitly what we had
 533                         // from the grammar, ERROR and then everything else
 534
 535                         case Token.READONLY:
 536                         case Token.OVERRIDE:
 537                         case Token.ERROR:
 538                                 return InputKind.Error;
 539
 540                         // This catches everything else allowed by
 541                         // expressions.  We could add one-by-one use cases
 542                         // if needed.
 543                         default:
 544                                 return InputKind.StatementOrExpression;
 545                         }
 546                 }
 547
 548                 //
 549                 // Parses the string @input and returns a CSharpParser if succeeful.
 550                 //
 551                 // if @silent is set to true then no errors are
 552                 // reported to the user.  This is used to do various calls to the
 553                 // parser and check if the expression is parsable.
 554                 //
 555                 // @partial_input: if @silent is true, then it returns whether the
 556                 // parsed expression was partial, and more data is needed
 557                 //
 558                 CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 559                 {
 560                         partial_input = false;
 561                         Reset ();
 562
 563                         var enc = ctx.Settings.Encoding;
 564                         var s = new MemoryStream (enc.GetBytes (input));
 565                         SeekableStreamReader seekable = new SeekableStreamReader (s, enc);
 566
 567                         InputKind kind = ToplevelOrStatement (seekable);
 568                         if (kind == InputKind.Error){
 569                                 if (mode == ParseMode.ReportErrors)
 570                                         ctx.Report.Error (-25, "Detection Parsing Error");
 571                                 partial_input = false;
 572                                 return null;
 573                         }
 574
 575                         if (kind == InputKind.EOF){
 576                                 if (mode == ParseMode.ReportErrors)
 577                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 578                                 partial_input = true;
 579                                 return null;
 580
 581                         }
 582                         seekable.Position = 0;
 583
 584                         source_file.DeclarationFound = false;
 585                         CSharpParser parser = new CSharpParser (seekable, source_file, new ParserSession ());
 586
 587                         if (kind == InputKind.StatementOrExpression){
 588                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 589                                 ctx.Settings.StatementMode = true;
 590                         } else {
 591                                 parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 592                                 ctx.Settings.StatementMode = false;
 593                         }
 594
 595                         if (mode == ParseMode.GetCompletions)
 596                                 parser.Lexer.CompleteOnEOF = true;
 597
 598                         ReportPrinter old_printer = null;
 599                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions))
 600                                 old_printer = ctx.Report.SetPrinter (new StreamReportPrinter (TextWriter.Null));
 601
 602                         try {
 603                                 parser.parse ();
 604                         } finally {
 605                                 if (ctx.Report.Errors != 0){
 606                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 607                                                 partial_input = true;
 608
 609                                         if (parser.undo != null)
 610                                                 parser.undo.ExecuteUndo ();
 611
 612                                         parser = null;
 613                                 }
 614
 615                                 if (old_printer != null)
 616                                         ctx.Report.SetPrinter (old_printer);
 617                         }
 618                         return parser;
 619                 }
 620
 621                 CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
 622                 {
 623 #if STATIC
 624                         throw new NotSupportedException ();
 625 #else
 626                         string current_debug_name = "eval-" + count + ".dll";
 627                         ++count;
 628
 629                         AssemblyDefinitionDynamic assembly;
 630                         AssemblyBuilderAccess access;
 631
 632                         if (Environment.GetEnvironmentVariable ("SAVE") != null) {
 633                                 access = AssemblyBuilderAccess.RunAndSave;
 634                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name, current_debug_name);
 635                                 assembly.Importer = importer;
 636                         } else {
 637 #if NET_4_0
 638                                 access = AssemblyBuilderAccess.RunAndCollect;
 639 #else
 640                                 access = AssemblyBuilderAccess.Run;
 641 #endif
 642                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name);
 643                         }
 644
 645                         assembly.Create (AppDomain.CurrentDomain, access);
 646
 647                         Method expression_method;
 648                         if (host != null) {
 649                                 var base_class_imported = importer.ImportType (base_class);
 650                                 var baseclass_list = new List<FullNamedExpression> (1) {
 651                                         new TypeExpression (base_class_imported, host.Location)
 652                                 };
 653
 654                                 host.AddBasesForPart (baseclass_list);
 655
 656                                 host.CreateContainer ();
 657                                 host.DefineContainer ();
 658                                 host.Define ();
 659
 660                                 expression_method = (Method) host.Members[0];
 661                         } else {
 662                                 expression_method = null;
 663                         }
 664
 665                         module.CreateContainer ();
 666
 667                         // Disable module and source file re-definition checks
 668                         module.EnableRedefinition ();
 669                         source_file.EnableRedefinition ();
 670
 671                         module.Define ();
 672
 673                         if (Report.Errors != 0){
 674                                 if (undo != null)
 675                                         undo.ExecuteUndo ();
 676
 677                                 return null;
 678                         }
 679
 680                         if (host != null){
 681                                 host.EmitContainer ();
 682                         }
 683
 684                         module.EmitContainer ();
 685                         if (Report.Errors != 0){
 686                                 if (undo != null)
 687                                         undo.ExecuteUndo ();
 688                                 return null;
 689                         }
 690
 691                         module.CloseContainer ();
 692                         if (host != null)
 693                                 host.CloseContainer ();
 694
 695                         if (access == AssemblyBuilderAccess.RunAndSave)
 696                                 assembly.Save ();
 697
 698                         if (host == null)
 699                                 return null;
 700
 701                         //
 702                         // Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
 703                         // work from MethodBuilders.   Retarded, I know.
 704                         //
 705                         var tt = assembly.Builder.GetType (host.TypeBuilder.Name);
 706                         var mi = tt.GetMethod (expression_method.MemberName.Name);
 707
 708                         //
 709                         // We need to then go from FieldBuilder to FieldInfo
 710                         // or reflection gets confused (it basically gets confused, and variables override each
 711                         // other).
 712                         //
 713                         foreach (var member in host.Members) {
 714                                 var field = member as Field;
 715                                 if (field == null)
 716                                         continue;
 717
 718                                 var fi = tt.GetField (field.Name);
 719
 720                                 Tuple<FieldSpec, FieldInfo> old;
 721
 722                                 // If a previous value was set, nullify it, so that we do
 723                                 // not leak memory
 724                                 if (fields.TryGetValue (field.Name, out old)) {
 725                                         if (old.Item1.MemberType.IsStruct) {
 726                                                 //
 727                                                 // TODO: Clear fields for structs
 728                                                 //
 729                                         } else {
 730                                                 try {
 731                                                         old.Item2.SetValue (null, null);
 732                                                 } catch {
 733                                                 }
 734                                         }
 735                                 }
 736
 737                                 fields[field.Name] = Tuple.Create (field.Spec, fi);
 738                         }
 739
 740                         return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
 741 #endif
 742                 }
 743
 744                 /// <summary>
 745                 ///   A sentinel value used to indicate that no value was
 746                 ///   was set by the compiled function.   This is used to
 747                 ///   differentiate between a function not returning a
 748                 ///   value and null.
 749                 /// </summary>
 750                 internal static class QuitValue { }
 751
 752                 internal Tuple<FieldSpec, FieldInfo> LookupField (string name)
 753                 {
 754                         Tuple<FieldSpec, FieldInfo> fi;
 755                         fields.TryGetValue (name, out fi);
 756                         return fi;
 757                 }
 758
 759                 static string Quote (string s)
 760                 {
 761                         if (s.IndexOf ('"') != -1)
 762                                 s = s.Replace ("\"", "\\\"");
 763
 764                         return "\"" + s + "\"";
 765                 }
 766
 767                 public string GetUsing ()
 768                 {
 769                         StringBuilder sb = new StringBuilder ();
 770                         // TODO:
 771                         //foreach (object x in ns.using_alias_list)
 772                         //    sb.AppendFormat ("using {0};\n", x);
 773
 774                         foreach (var ue in source_file.Usings) {
 775                                 sb.AppendFormat ("using {0};", ue.ToString ());
 776                                 sb.Append (Environment.NewLine);
 777                         }
 778
 779                         return sb.ToString ();
 780                 }
 781
 782                 internal List<string> GetUsingList ()
 783                 {
 784                         var res = new List<string> ();
 785
 786                         foreach (var ue in source_file.Usings) {
 787                                 if (ue.Alias != null || ue.ResolvedExpression == null)
 788                                         continue;
 789
 790                                 res.Add (ue.NamespaceExpression.Name);
 791                         }
 792
 793                         return res;
 794                 }
 795
 796                 internal string [] GetVarNames ()
 797                 {
 798                         lock (evaluator_lock){
 799                                 return new List<string> (fields.Keys).ToArray ();
 800                         }
 801                 }
 802
 803                 public string GetVars ()
 804                 {
 805                         lock (evaluator_lock){
 806                                 StringBuilder sb = new StringBuilder ();
 807
 808                                 foreach (var de in fields){
 809                                         var fi = LookupField (de.Key);
 810                                         object value;
 811                                         try {
 812                                                 value = fi.Item2.GetValue (null);
 813                                                 if (value is string)
 814                                                         value = Quote ((string)value);
 815                                         } catch {
 816                                                 value = "<error reading value>";
 817                                         }
 818
 819                                         sb.AppendFormat ("{0} {1} = {2}", fi.Item1.MemberType.GetSignatureForError (), de.Key, value);
 820                                         sb.AppendLine ();
 821                                 }
 822
 823                                 return sb.ToString ();
 824                         }
 825                 }
 826
 827                 /// <summary>
 828                 ///    Loads the given assembly and exposes the API to the user.
 829                 /// </summary>
 830                 public void LoadAssembly (string file)
 831                 {
 832                         var loader = new DynamicLoader (importer, ctx);
 833                         var assembly = loader.LoadAssemblyFile (file, false);
 834                         if (assembly == null)
 835                                 return;
 836
 837                         lock (evaluator_lock){
 838                                 importer.ImportAssembly (assembly, module.GlobalRootNamespace);
 839                         }
 840                 }
 841
 842                 /// <summary>
 843                 ///    Exposes the API of the given assembly to the Evaluator
 844                 /// </summary>
 845                 public void ReferenceAssembly (Assembly a)
 846                 {
 847                         lock (evaluator_lock){
 848                                 importer.ImportAssembly (a, module.GlobalRootNamespace);
 849                         }
 850                 }
 851         }
 852
 853
 854         /// <summary>
 855         ///   A delegate that can be used to invoke the
 856         ///   compiled expression or statement.
 857         /// </summary>
 858         /// <remarks>
 859         ///   Since the Compile methods will compile
 860         ///   statements and expressions into the same
 861         ///   delegate, you can tell if a value was returned
 862         ///   by checking whether the returned value is of type
 863         ///   NoValueSet.
 864         /// </remarks>
 865
 866         public delegate void CompiledMethod (ref object retvalue);
 867
 868         /// <summary>
 869         ///   The default base class for every interaction line
 870         /// </summary>
 871         /// <remarks>
 872         ///   The expressions and statements behave as if they were
 873         ///   a static method of this class.   The InteractiveBase class
 874         ///   contains a number of useful methods, but can be overwritten
 875         ///   by setting the InteractiveBaseType property in the Evaluator
 876         /// </remarks>
 877         public class InteractiveBase {
 878                 /// <summary>
 879                 ///   Determines where the standard output of methods in this class will go.
 880                 /// </summary>
 881                 public static TextWriter Output = Console.Out;
 882
 883                 /// <summary>
 884                 ///   Determines where the standard error of methods in this class will go.
 885                 /// </summary>
 886                 public static TextWriter Error = Console.Error;
 887
 888                 /// <summary>
 889                 ///   The primary prompt used for interactive use.
 890                 /// </summary>
 891                 public static string Prompt             = "csharp> ";
 892
 893                 /// <summary>
 894                 ///   The secondary prompt used for interactive use (used when
 895                 ///   an expression is incomplete).
 896                 /// </summary>
 897                 public static string ContinuationPrompt = "      > ";
 898
 899                 /// <summary>
 900                 ///   Used to signal that the user has invoked the  `quit' statement.
 901                 /// </summary>
 902                 public static bool QuitRequested;
 903
 904                 public static Evaluator Evaluator;
 905
 906                 /// <summary>
 907                 ///   Shows all the variables defined so far.
 908                 /// </summary>
 909                 static public void ShowVars ()
 910                 {
 911                         Output.Write (Evaluator.GetVars ());
 912                         Output.Flush ();
 913                 }
 914
 915                 /// <summary>
 916                 ///   Displays the using statements in effect at this point.
 917                 /// </summary>
 918                 static public void ShowUsing ()
 919                 {
 920                         Output.Write (Evaluator.GetUsing ());
 921                         Output.Flush ();
 922                 }
 923
 924                 /// <summary>
 925                 ///   Times the execution of the given delegate
 926                 /// </summary>
 927                 static public TimeSpan Time (Action a)
 928                 {
 929                         DateTime start = DateTime.Now;
 930                         a ();
 931                         return DateTime.Now - start;
 932                 }
 933
 934                 /// <summary>
 935                 ///   Loads the assemblies from a package
 936                 /// </summary>
 937                 /// <remarks>
 938                 ///   Loads the assemblies from a package.   This is equivalent
 939                 ///   to passing the -pkg: command line flag to the C# compiler
 940                 ///   on the command line.
 941                 /// </remarks>
 942                 static public void LoadPackage (string pkg)
 943                 {
 944                         if (pkg == null){
 945                                 Error.WriteLine ("Invalid package specified");
 946                                 return;
 947                         }
 948
 949                         string pkgout = Driver.GetPackageFlags (pkg, null);
 950
 951                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
 952                                 Split (new Char [] { ' ', '\t'});
 953
 954                         foreach (string s in xargs){
 955                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
 956                                         string lib = s.Substring (s.IndexOf (':')+1);
 957
 958                                         Evaluator.LoadAssembly (lib);
 959                                         continue;
 960                                 }
 961                         }
 962                 }
 963
 964                 /// <summary>
 965                 ///   Loads the assembly
 966                 /// </summary>
 967                 /// <remarks>
 968                 ///   Loads the specified assembly and makes its types
 969                 ///   available to the evaluator.  This is equivalent
 970                 ///   to passing the -pkg: command line flag to the C#
 971                 ///   compiler on the command line.
 972                 /// </remarks>
 973                 static public void LoadAssembly (string assembly)
 974                 {
 975                         Evaluator.LoadAssembly (assembly);
 976                 }
 977
 978                 static public void print (object obj)
 979                 {
 980                         Output.WriteLine (obj);
 981                 }
 982
 983                 static public void print (string fmt, params object [] args)
 984                 {
 985                         Output.WriteLine (fmt, args);
 986                 }
 987
 988                 /// <summary>
 989                 ///   Returns a list of available static methods.
 990                 /// </summary>
 991                 static public string help {
 992                         get {
 993                                 return "Static methods:\n" +
 994 #if !NET_2_1
 995                                         "  Describe (object);       - Describes the object's type\n" +
 996 #endif
 997                                         "  LoadPackage (package);   - Loads the given Package (like -pkg:FILE)\n" +
 998                                         "  LoadAssembly (assembly); - Loads the given assembly (like -r:ASSEMBLY)\n" +
 999                                         "  ShowVars ();             - Shows defined local variables.\n" +
1000                                         "  ShowUsing ();            - Show active using declarations.\n" +
1001                                         "  Prompt                   - The prompt used by the C# shell\n" +
1002                                         "  ContinuationPrompt       - The prompt for partial input\n" +
1003                                         "  Time (() => { });        - Times the specified code\n" +
1004                                         "  print (obj);             - Shorthand for Console.WriteLine\n" +
1005                                         "  quit;                    - You'll never believe it - this quits the repl!\n" +
1006                                         "  help;                    - This help text\n";
1007                         }
1008                 }
1009
1010                 /// <summary>
1011                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1012                 /// </summary>
1013                 static public object quit {
1014                         get {
1015                                 QuitRequested = true;
1016
1017                                 // To avoid print null at the exit
1018                                 return typeof (Evaluator.QuitValue);
1019                         }
1020                 }
1021
1022                 /// <summary>
1023                 ///   Same as quit - useful in script scenerios
1024                 /// </summary>
1025                 static public void Quit () {
1026                         QuitRequested = true;
1027                 }
1028
1029 #if !NET_2_1
1030                 /// <summary>
1031                 ///   Describes an object or a type.
1032                 /// </summary>
1033                 /// <remarks>
1034                 ///   This method will show a textual representation
1035                 ///   of the object's type.  If the object is a
1036                 ///   System.Type it renders the type directly,
1037                 ///   otherwise it renders the type returned by
1038                 ///   invoking GetType on the object.
1039                 /// </remarks>
1040                 static public string Describe (object x)
1041                 {
1042                         if (x == null)
1043                                 return "<null>";
1044
1045                         var type = x as Type ?? x.GetType ();
1046
1047                         StringWriter sw = new StringWriter ();
1048                         new Outline (type, sw, true, false, false).OutlineType ();
1049                         return sw.ToString ();
1050                 }
1051 #endif
1052         }
1053
1054         class HoistedEvaluatorVariable : HoistedVariable
1055         {
1056                 public HoistedEvaluatorVariable (Field field)
1057                         : base (null, field)
1058                 {
1059                 }
1060
1061                 protected override FieldExpr GetFieldExpression (EmitContext ec)
1062                 {
1063                         return new FieldExpr (field, field.Location);
1064                 }
1065         }
1066
1067         /// <summary>
1068         ///    A class used to assign values if the source expression is not void
1069         ///
1070         ///    Used by the interactive shell to allow it to call this code to set
1071         ///    the return value for an invocation.
1072         /// </summary>
1073         class OptionalAssign : SimpleAssign {
1074                 public OptionalAssign (Expression t, Expression s, Location loc)
1075                         : base (t, s, loc)
1076                 {
1077                 }
1078
1079                 protected override Expression DoResolve (ResolveContext ec)
1080                 {
1081                         Expression clone = source.Clone (new CloneContext ());
1082
1083                         clone = clone.Resolve (ec);
1084                         if (clone == null)
1085                                 return null;
1086
1087                         //
1088                         // A useful feature for the REPL: if we can resolve the expression
1089                         // as a type, Describe the type;
1090                         //
1091                         if (ec.Module.Evaluator.DescribeTypeExpressions){
1092                                 var old_printer = ec.Report.SetPrinter (new SessionReportPrinter ());
1093                                 Expression tclone;
1094                                 try {
1095                                         // Note: clone context cannot be shared otherwise block mapping would leak
1096                                         tclone = source.Clone (new CloneContext ());
1097                                         tclone = tclone.Resolve (ec, ResolveFlags.Type);
1098                                         if (ec.Report.Errors > 0)
1099                                                 tclone = null;
1100                                 } finally {
1101                                         ec.Report.SetPrinter (old_printer);
1102                                 }
1103
1104                                 if (tclone is TypeExpr) {
1105                                         Arguments args = new Arguments (1);
1106                                         args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
1107                                         return new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
1108                                 }
1109                         }
1110
1111                         // This means its really a statement.
1112                         if (clone.Type.Kind == MemberKind.Void || clone is DynamicInvocation || clone is Assign) {
1113                                 return clone;
1114                         }
1115
1116                         source = clone;
1117                         return base.DoResolve (ec);
1118                 }
1119         }
1120
1121         public class Undo
1122         {
1123                 List<Action> undo_actions;
1124
1125                 public Undo ()
1126                 {
1127                 }
1128
1129                 public void AddTypeContainer (TypeContainer current_container, TypeDefinition tc)
1130                 {
1131                         if (current_container == tc){
1132                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1133                                 return;
1134                         }
1135
1136                         if (undo_actions == null)
1137                                 undo_actions = new List<Action> ();
1138
1139                         var existing = current_container.Containers.FirstOrDefault (l => l.Basename == tc.Basename);
1140                         if (existing != null) {
1141                                 current_container.RemoveContainer (existing);
1142                                 undo_actions.Add (() => current_container.AddTypeContainer (existing));
1143                         }
1144
1145                         undo_actions.Add (() => current_container.RemoveContainer (tc));
1146                 }
1147
1148                 public void ExecuteUndo ()
1149                 {
1150                         if (undo_actions == null)
1151                                 return;
1152
1153                         foreach (var p in undo_actions){
1154                                 p ();
1155                         }
1156
1157                         undo_actions = null;
1158                 }
1159         }
1160
1161 }