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