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 //
   7 // Dual licensed under the terms of the MIT X11 or GNU GPL
   8 //
   9 // Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
  10 // Copyright 2004, 2005, 2006, 2007, 2008 Novell, Inc
  11 //
  12
  13 using System;
  14 using System.Threading;
  15 using System.Collections.Generic;
  16 using System.Reflection;
  17 using System.Reflection.Emit;
  18 using System.IO;
  19 using System.Text;
  20
  21 namespace Mono.CSharp
  22 {
  23
  24         /// <summary>
  25         ///   Evaluator: provides an API to evaluate C# statements and
  26         ///   expressions dynamically.
  27         /// </summary>
  28         /// <remarks>
  29         ///   This class exposes static methods to evaluate expressions in the
  30         ///   current program.
  31         ///
  32         ///   To initialize the evaluator with a number of compiler
  33         ///   options call the Init(string[]args) method with a set of
  34         ///   command line options that the compiler recognizes.
  35         ///
  36         ///   To interrupt execution of a statement, you can invoke the
  37         ///   Evaluator.Interrupt method.
  38         /// </remarks>
  39         public class Evaluator {
  40
  41                 enum ParseMode {
  42                         // Parse silently, do not output any error messages
  43                         Silent,
  44
  45                         // Report errors during parse
  46                         ReportErrors,
  47
  48                         // Auto-complete, means that the tokenizer will start producing
  49                         // GETCOMPLETIONS tokens when it reaches a certain point.
  50                         GetCompletions
  51                 }
  52
  53                 static object evaluator_lock = new object ();
  54
  55                 static string current_debug_name;
  56                 static int count;
  57                 static Thread invoke_thread;
  58
  59                 static List<NamespaceEntry.UsingAliasEntry> using_alias_list = new List<NamespaceEntry.UsingAliasEntry> ();
  60                 internal static List<NamespaceEntry.UsingEntry> using_list = new List<NamespaceEntry.UsingEntry> ();
  61                 static Dictionary<string, Tuple<FieldSpec, FieldInfo>> fields = new Dictionary<string, Tuple<FieldSpec, FieldInfo>> ();
  62
  63                 static TypeSpec interactive_base_class;
  64                 static Driver driver;
  65                 static bool inited;
  66
  67                 static CompilerContext ctx;
  68                 static DynamicLoader loader;
  69
  70                 public static TextWriter MessageOutput = Console.Out;
  71
  72                 /// <summary>
  73                 ///   Optional initialization for the Evaluator.
  74                 /// </summary>
  75                 /// <remarks>
  76                 ///  Initializes the Evaluator with the command line options
  77                 ///  that would be processed by the command line compiler.  Only
  78                 ///  the first call to Init will work, any future invocations are
  79                 ///  ignored.
  80                 ///
  81                 ///  You can safely avoid calling this method if your application
  82                 ///  does not need any of the features exposed by the command line
  83                 ///  interface.
  84                 /// </remarks>
  85                 public static void Init (string [] args)
  86                 {
  87                         InitAndGetStartupFiles (args);
  88                 }
  89
  90                 internal static ReportPrinter SetPrinter (ReportPrinter report_printer)
  91                 {
  92                         return ctx.Report.SetPrinter (report_printer);
  93                 }
  94
  95                 /// <summary>
  96                 ///   Optional initialization for the Evaluator.
  97                 /// </summary>
  98                 /// <remarks>
  99                 ///  Initializes the Evaluator with the command line
 100                 ///  options that would be processed by the command
 101                 ///  line compiler.  Only the first call to
 102                 ///  InitAndGetStartupFiles or Init will work, any future
 103                 ///  invocations are ignored.
 104                 ///
 105                 ///  You can safely avoid calling this method if your application
 106                 ///  does not need any of the features exposed by the command line
 107                 ///  interface.
 108                 ///
 109                 ///  This method return an array of strings that contains any
 110                 ///  files that were specified in `args'.
 111                 /// </remarks>
 112                 public static string [] InitAndGetStartupFiles (string [] args)
 113                 {
 114                         lock (evaluator_lock){
 115                                 if (inited)
 116                                         return new string [0];
 117
 118                                 driver = Driver.Create (args, false, new ConsoleReportPrinter ());
 119                                 if (driver == null)
 120                                         throw new Exception ("Failed to create compiler driver with the given arguments");
 121
 122                                 ctx = driver.ctx;
 123
 124                                 CompilerCallableEntryPoint.Reset ();
 125                                 RootContext.ToplevelTypes = new ModuleContainer (ctx);
 126
 127                                 var startup_files = new List<string> ();
 128                                 foreach (CompilationUnit file in Location.SourceFiles)
 129                                         startup_files.Add (file.Path);
 130
 131                                 CompilerCallableEntryPoint.PartialReset ();
 132
 133                                 var importer = new ReflectionImporter (ctx.BuildinTypes);
 134                                 loader = new DynamicLoader (importer, ctx);
 135
 136                                 RootContext.ToplevelTypes.SetDeclaringAssembly (new AssemblyDefinitionDynamic (RootContext.ToplevelTypes, "temp"));
 137
 138                                 loader.LoadReferences (RootContext.ToplevelTypes);
 139                                 ctx.BuildinTypes.CheckDefinitions (RootContext.ToplevelTypes);
 140                                 RootContext.ToplevelTypes.InitializePredefinedTypes ();
 141
 142                                 RootContext.EvalMode = true;
 143                                 inited = true;
 144
 145                                 return startup_files.ToArray ();
 146                         }
 147                 }
 148
 149                 static void Init ()
 150                 {
 151                         Init (new string [0]);
 152                 }
 153
 154                 static void Reset ()
 155                 {
 156                         CompilerCallableEntryPoint.PartialReset ();
 157
 158                         Location.AddFile (null, "{interactive}");
 159                         Location.Initialize ();
 160
 161                         current_debug_name = "interactive" + (count++) + ".dll";
 162                 }
 163
 164                 /// <summary>
 165                 ///   The base class for the classes that host the user generated code
 166                 /// </summary>
 167                 /// <remarks>
 168                 ///
 169                 ///   This is the base class that will host the code
 170                 ///   executed by the Evaluator.  By default
 171                 ///   this is the Mono.CSharp.InteractiveBase class
 172                 ///   which is useful for interactive use.
 173                 ///
 174                 ///   By changing this property you can control the
 175                 ///   base class and the static members that are
 176                 ///   available to your evaluated code.
 177                 /// </remarks>
 178                 static public TypeSpec InteractiveBaseClass {
 179                         get {
 180                                 if (interactive_base_class != null)
 181                                         return interactive_base_class;
 182
 183                                 return loader.Importer.ImportType (typeof (InteractiveBase));
 184                         }
 185                 }
 186
 187                 public static void SetInteractiveBaseClass (Type type)
 188                 {
 189                         if (type == null)
 190                                 throw new ArgumentNullException ();
 191
 192                         lock (evaluator_lock)
 193                                 interactive_base_class = loader.Importer.ImportType (type);
 194                 }
 195
 196                 /// <summary>
 197                 ///   Interrupts the evaluation of an expression executing in Evaluate.
 198                 /// </summary>
 199                 /// <remarks>
 200                 ///   Use this method to interrupt long-running invocations.
 201                 /// </remarks>
 202                 public static void Interrupt ()
 203                 {
 204                         if (!inited || !invoking)
 205                                 return;
 206
 207                         if (invoke_thread != null)
 208                                 invoke_thread.Abort ();
 209                 }
 210
 211                 /// <summary>
 212                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 213                 /// </summary>
 214                 /// <remarks>
 215                 ///
 216                 ///   Compiles the input string as a C# expression or
 217                 ///   statement, unlike the Evaluate method, the
 218                 ///   resulting delegate can be invoked multiple times
 219                 ///   without incurring in the compilation overhead.
 220                 ///
 221                 ///   If the return value of this function is null,
 222                 ///   this indicates that the parsing was complete.
 223                 ///   If the return value is a string it indicates
 224                 ///   that the input string was partial and that the
 225                 ///   invoking code should provide more code before
 226                 ///   the code can be successfully compiled.
 227                 ///
 228                 ///   If you know that you will always get full expressions or
 229                 ///   statements and do not care about partial input, you can use
 230                 ///   the other Compile overload.
 231                 ///
 232                 ///   On success, in addition to returning null, the
 233                 ///   compiled parameter will be set to the delegate
 234                 ///   that can be invoked to execute the code.
 235                 ///
 236                 /// </remarks>
 237                 static public string Compile (string input, out CompiledMethod compiled)
 238                 {
 239                         if (input == null || input.Length == 0){
 240                                 compiled = null;
 241                                 return null;
 242                         }
 243
 244                         lock (evaluator_lock){
 245                                 if (!inited)
 246                                         Init ();
 247                                 else
 248                                         ctx.Report.Printer.Reset ();
 249
 250                         //      RootContext.ToplevelTypes = new ModuleContainer (ctx);
 251
 252                                 bool partial_input;
 253                                 CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
 254                                 if (parser == null){
 255                                         compiled = null;
 256                                         if (partial_input)
 257                                                 return input;
 258
 259                                         ParseString (ParseMode.ReportErrors, input, out partial_input);
 260                                         return null;
 261                                 }
 262
 263                                 object parser_result = parser.InteractiveResult;
 264
 265                                 if (!(parser_result is Class)){
 266                                         int errors = ctx.Report.Errors;
 267
 268                                         NamespaceEntry.VerifyAllUsing ();
 269                                         if (errors == ctx.Report.Errors)
 270                                                 parser.CurrentNamespace.Extract (using_alias_list, using_list);
 271                                 }
 272
 273 #if STATIC
 274                                 throw new NotSupportedException ();
 275 #else
 276                                 compiled = CompileBlock (parser_result as Class, parser.undo, ctx.Report);
 277                                 return null;
 278 #endif
 279                         }
 280                 }
 281
 282                 /// <summary>
 283                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 284                 /// </summary>
 285                 /// <remarks>
 286                 ///
 287                 ///   Compiles the input string as a C# expression or
 288                 ///   statement, unlike the Evaluate method, the
 289                 ///   resulting delegate can be invoked multiple times
 290                 ///   without incurring in the compilation overhead.
 291                 ///
 292                 ///   This method can only deal with fully formed input
 293                 ///   strings and does not provide a completion mechanism.
 294                 ///   If you must deal with partial input (for example for
 295                 ///   interactive use) use the other overload.
 296                 ///
 297                 ///   On success, a delegate is returned that can be used
 298                 ///   to invoke the method.
 299                 ///
 300                 /// </remarks>
 301                 static public CompiledMethod Compile (string input)
 302                 {
 303                         CompiledMethod compiled;
 304
 305                         // Ignore partial inputs
 306                         if (Compile (input, out compiled) != null){
 307                                 // Error, the input was partial.
 308                                 return null;
 309                         }
 310
 311                         // Either null (on error) or the compiled method.
 312                         return compiled;
 313                 }
 314
 315                 //
 316                 // Todo: Should we handle errors, or expect the calling code to setup
 317                 // the recording themselves?
 318                 //
 319
 320                 /// <summary>
 321                 ///   Evaluates and expression or statement and returns any result values.
 322                 /// </summary>
 323                 /// <remarks>
 324                 ///   Evaluates the input string as a C# expression or
 325                 ///   statement.  If the input string is an expression
 326                 ///   the result will be stored in the result variable
 327                 ///   and the result_set variable will be set to true.
 328                 ///
 329                 ///   It is necessary to use the result/result_set
 330                 ///   pair to identify when a result was set (for
 331                 ///   example, execution of user-provided input can be
 332                 ///   an expression, a statement or others, and
 333                 ///   result_set would only be set if the input was an
 334                 ///   expression.
 335                 ///
 336                 ///   If the return value of this function is null,
 337                 ///   this indicates that the parsing was complete.
 338                 ///   If the return value is a string, it indicates
 339                 ///   that the input is partial and that the user
 340                 ///   should provide an updated string.
 341                 /// </remarks>
 342                 public static string Evaluate (string input, out object result, out bool result_set)
 343                 {
 344                         CompiledMethod compiled;
 345
 346                         result_set = false;
 347                         result = null;
 348
 349                         input = Compile (input, out compiled);
 350                         if (input != null)
 351                                 return input;
 352
 353                         if (compiled == null)
 354                                 return null;
 355
 356                         //
 357                         // The code execution does not need to keep the compiler lock
 358                         //
 359                         object retval = typeof (NoValueSet);
 360
 361                         try {
 362                                 invoke_thread = System.Threading.Thread.CurrentThread;
 363                                 invoking = true;
 364                                 compiled (ref retval);
 365                         } catch (ThreadAbortException e){
 366                                 Thread.ResetAbort ();
 367                                 Console.WriteLine ("Interrupted!\n{0}", e);
 368                         } finally {
 369                                 invoking = false;
 370                         }
 371
 372                         //
 373                         // We use a reference to a compiler type, in this case
 374                         // Driver as a flag to indicate that this was a statement
 375                         //
 376                         if (retval != typeof (NoValueSet)){
 377                                 result_set = true;
 378                                 result = retval;
 379                         }
 380
 381                         return null;
 382                 }
 383
 384                 public static string [] GetCompletions (string input, out string prefix)
 385                 {
 386                         prefix = "";
 387                         if (input == null || input.Length == 0)
 388                                 return null;
 389
 390                         lock (evaluator_lock){
 391                                 if (!inited)
 392                                         Init ();
 393
 394                                 bool partial_input;
 395                                 CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
 396                                 if (parser == null){
 397                                         if (CSharpParser.yacc_verbose_flag != 0)
 398                                                 Console.WriteLine ("DEBUG: No completions available");
 399                                         return null;
 400                                 }
 401
 402                                 Class parser_result = parser.InteractiveResult as Class;
 403
 404                                 if (parser_result == null){
 405                                         if (CSharpParser.yacc_verbose_flag != 0)
 406                                                 Console.WriteLine ("Do not know how to cope with !Class yet");
 407                                         return null;
 408                                 }
 409
 410                                 try {
 411                                         var a = new AssemblyDefinitionDynamic (RootContext.ToplevelTypes, "temp");
 412                                         a.Create (AppDomain.CurrentDomain, AssemblyBuilderAccess.Run);
 413                                         RootContext.ToplevelTypes.SetDeclaringAssembly (a);
 414                                         RootContext.ToplevelTypes.Define ();
 415                                         if (ctx.Report.Errors != 0)
 416                                                 return null;
 417
 418                                         MethodOrOperator method = null;
 419                                         foreach (MemberCore member in parser_result.Methods){
 420                                                 if (member.Name != "Host")
 421                                                         continue;
 422
 423                                                 method = (MethodOrOperator) member;
 424                                                 break;
 425                                         }
 426                                         if (method == null)
 427                                                 throw new InternalErrorException ("did not find the the Host method");
 428
 429                                         BlockContext bc = new BlockContext (method, method.Block, method.ReturnType);
 430
 431                                         try {
 432                                                 method.Block.Resolve (null, bc, method);
 433                                         } catch (CompletionResult cr){
 434                                                 prefix = cr.BaseText;
 435                                                 return cr.Result;
 436                                         }
 437                                 } finally {
 438                                         parser.undo.ExecuteUndo ();
 439                                 }
 440
 441                         }
 442                         return null;
 443                 }
 444
 445                 /// <summary>
 446                 ///   Executes the given expression or statement.
 447                 /// </summary>
 448                 /// <remarks>
 449                 ///    Executes the provided statement, returns true
 450                 ///    on success, false on parsing errors.  Exceptions
 451                 ///    might be thrown by the called code.
 452                 /// </remarks>
 453                 public static bool Run (string statement)
 454                 {
 455                         if (!inited)
 456                                 Init ();
 457
 458                         object result;
 459                         bool result_set;
 460
 461                         bool ok = Evaluate (statement, out result, out result_set) == null;
 462
 463                         return ok;
 464                 }
 465
 466                 /// <summary>
 467                 ///   Evaluates and expression or statement and returns the result.
 468                 /// </summary>
 469                 /// <remarks>
 470                 ///   Evaluates the input string as a C# expression or
 471                 ///   statement and returns the value.
 472                 ///
 473                 ///   This method will throw an exception if there is a syntax error,
 474                 ///   of if the provided input is not an expression but a statement.
 475                 /// </remarks>
 476                 public static object Evaluate (string input)
 477                 {
 478                         object result;
 479                         bool result_set;
 480
 481                         string r = Evaluate (input, out result, out result_set);
 482
 483                         if (r != null)
 484                                 throw new ArgumentException ("Syntax error on input: partial input");
 485
 486                         if (result_set == false)
 487                                 throw new ArgumentException ("The expression did not set a result");
 488
 489                         return result;
 490                 }
 491
 492                 enum InputKind {
 493                         EOF,
 494                         StatementOrExpression,
 495                         CompilationUnit,
 496                         Error
 497                 }
 498
 499                 //
 500                 // Deambiguates the input string to determine if we
 501                 // want to process a statement or if we want to
 502                 // process a compilation unit.
 503                 //
 504                 // This is done using a top-down predictive parser,
 505                 // since the yacc/jay parser can not deambiguage this
 506                 // without more than one lookahead token.   There are very
 507                 // few ambiguities.
 508                 //
 509                 static InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 510                 {
 511                         Tokenizer tokenizer = new Tokenizer (seekable, (CompilationUnit) Location.SourceFiles [0], ctx);
 512
 513                         int t = tokenizer.token ();
 514                         switch (t){
 515                         case Token.EOF:
 516                                 return InputKind.EOF;
 517
 518                         // These are toplevels
 519                         case Token.EXTERN:
 520                         case Token.OPEN_BRACKET:
 521                         case Token.ABSTRACT:
 522                         case Token.CLASS:
 523                         case Token.ENUM:
 524                         case Token.INTERFACE:
 525                         case Token.INTERNAL:
 526                         case Token.NAMESPACE:
 527                         case Token.PRIVATE:
 528                         case Token.PROTECTED:
 529                         case Token.PUBLIC:
 530                         case Token.SEALED:
 531                         case Token.STATIC:
 532                         case Token.STRUCT:
 533                                 return InputKind.CompilationUnit;
 534
 535                         // Definitely expression
 536                         case Token.FIXED:
 537                         case Token.BOOL:
 538                         case Token.BYTE:
 539                         case Token.CHAR:
 540                         case Token.DECIMAL:
 541                         case Token.DOUBLE:
 542                         case Token.FLOAT:
 543                         case Token.INT:
 544                         case Token.LONG:
 545                         case Token.NEW:
 546                         case Token.OBJECT:
 547                         case Token.SBYTE:
 548                         case Token.SHORT:
 549                         case Token.STRING:
 550                         case Token.UINT:
 551                         case Token.ULONG:
 552                                 return InputKind.StatementOrExpression;
 553
 554                         // These need deambiguation help
 555                         case Token.USING:
 556                                 t = tokenizer.token ();
 557                                 if (t == Token.EOF)
 558                                         return InputKind.EOF;
 559
 560                                 if (t == Token.IDENTIFIER)
 561                                         return InputKind.CompilationUnit;
 562                                 return InputKind.StatementOrExpression;
 563
 564
 565                         // Distinguish between:
 566                         //    delegate opt_anonymous_method_signature block
 567                         //    delegate type
 568                         case Token.DELEGATE:
 569                                 t = tokenizer.token ();
 570                                 if (t == Token.EOF)
 571                                         return InputKind.EOF;
 572                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 573                                         return InputKind.StatementOrExpression;
 574                                 return InputKind.CompilationUnit;
 575
 576                         // Distinguih between:
 577                         //    unsafe block
 578                         //    unsafe as modifier of a type declaration
 579                         case Token.UNSAFE:
 580                                 t = tokenizer.token ();
 581                                 if (t == Token.EOF)
 582                                         return InputKind.EOF;
 583                                 if (t == Token.OPEN_PARENS)
 584                                         return InputKind.StatementOrExpression;
 585                                 return InputKind.CompilationUnit;
 586
 587                         // These are errors: we list explicitly what we had
 588                         // from the grammar, ERROR and then everything else
 589
 590                         case Token.READONLY:
 591                         case Token.OVERRIDE:
 592                         case Token.ERROR:
 593                                 return InputKind.Error;
 594
 595                         // This catches everything else allowed by
 596                         // expressions.  We could add one-by-one use cases
 597                         // if needed.
 598                         default:
 599                                 return InputKind.StatementOrExpression;
 600                         }
 601                 }
 602
 603                 //
 604                 // Parses the string @input and returns a CSharpParser if succeeful.
 605                 //
 606                 // if @silent is set to true then no errors are
 607                 // reported to the user.  This is used to do various calls to the
 608                 // parser and check if the expression is parsable.
 609                 //
 610                 // @partial_input: if @silent is true, then it returns whether the
 611                 // parsed expression was partial, and more data is needed
 612                 //
 613                 static CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 614                 {
 615                         partial_input = false;
 616                         Reset ();
 617                         queued_fields.Clear ();
 618                         Tokenizer.LocatedToken.Initialize ();
 619
 620                         Stream s = new MemoryStream (Encoding.Default.GetBytes (input));
 621                         SeekableStreamReader seekable = new SeekableStreamReader (s, Encoding.Default);
 622
 623                         InputKind kind = ToplevelOrStatement (seekable);
 624                         if (kind == InputKind.Error){
 625                                 if (mode == ParseMode.ReportErrors)
 626                                         ctx.Report.Error (-25, "Detection Parsing Error");
 627                                 partial_input = false;
 628                                 return null;
 629                         }
 630
 631                         if (kind == InputKind.EOF){
 632                                 if (mode == ParseMode.ReportErrors)
 633                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 634                                 partial_input = true;
 635                                 return null;
 636
 637                         }
 638                         seekable.Position = 0;
 639
 640                         CSharpParser parser = new CSharpParser (seekable, Location.SourceFiles [0], RootContext.ToplevelTypes);
 641
 642                         if (kind == InputKind.StatementOrExpression){
 643                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 644                                 RootContext.StatementMode = true;
 645                         } else {
 646                                 //
 647                                 // Do not activate EvalCompilationUnitParserCharacter until
 648                                 // I have figured out all the limitations to invoke methods
 649                                 // in the generated classes.  See repl.txt
 650                                 //
 651                                 parser.Lexer.putback_char = Tokenizer.EvalUsingDeclarationsParserCharacter;
 652                                 //parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 653                                 RootContext.StatementMode = false;
 654                         }
 655
 656                         if (mode == ParseMode.GetCompletions)
 657                                 parser.Lexer.CompleteOnEOF = true;
 658
 659                         ReportPrinter old_printer = null;
 660                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions) && CSharpParser.yacc_verbose_flag == 0)
 661                                 old_printer = SetPrinter (new StreamReportPrinter (TextWriter.Null));
 662
 663                         try {
 664                                 parser.parse ();
 665                         } finally {
 666                                 if (ctx.Report.Errors != 0){
 667                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 668                                                 partial_input = true;
 669
 670                                         parser.undo.ExecuteUndo ();
 671                                         parser = null;
 672                                 }
 673
 674                                 if (old_printer != null)
 675                                         SetPrinter (old_printer);
 676                         }
 677                         return parser;
 678                 }
 679
 680                 //
 681                 // Queue all the fields that we use, as we need to then go from FieldBuilder to FieldInfo
 682                 // or reflection gets confused (it basically gets confused, and variables override each
 683                 // other).
 684                 //
 685                 static List<Field> queued_fields = new List<Field> ();
 686
 687                 //static ArrayList types = new ArrayList ();
 688
 689                 static volatile bool invoking;
 690 #if !STATIC
 691                 static CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
 692                 {
 693                         AssemblyDefinitionDynamic assembly;
 694
 695                         if (Environment.GetEnvironmentVariable ("SAVE") != null) {
 696                                 assembly = new AssemblyDefinitionDynamic (RootContext.ToplevelTypes, current_debug_name, current_debug_name);
 697                                 assembly.Importer = loader.Importer;
 698                         } else {
 699                                 assembly = new AssemblyDefinitionDynamic (RootContext.ToplevelTypes, current_debug_name);
 700                         }
 701
 702                         assembly.Create (AppDomain.CurrentDomain, AssemblyBuilderAccess.RunAndSave);
 703                         RootContext.ToplevelTypes.SetDeclaringAssembly (assembly);
 704                         RootContext.ToplevelTypes.Define ();
 705
 706                         if (Report.Errors != 0){
 707                                 undo.ExecuteUndo ();
 708                                 return null;
 709                         }
 710
 711                         TypeBuilder tb = null;
 712                         MethodBuilder mb = null;
 713
 714                         if (host != null){
 715                                 tb = host.TypeBuilder;
 716                                 mb = null;
 717                                 foreach (MemberCore member in host.Methods){
 718                                         if (member.Name != "Host")
 719                                                 continue;
 720
 721                                         MethodOrOperator method = (MethodOrOperator) member;
 722                                         mb = method.MethodBuilder;
 723                                         break;
 724                                 }
 725
 726                                 if (mb == null)
 727                                         throw new Exception ("Internal error: did not find the method builder for the generated method");
 728                         }
 729
 730                         RootContext.ToplevelTypes.Emit ();
 731                         if (Report.Errors != 0){
 732                                 undo.ExecuteUndo ();
 733                                 return null;
 734                         }
 735
 736                         RootContext.ToplevelTypes.CloseType ();
 737
 738                         if (Environment.GetEnvironmentVariable ("SAVE") != null)
 739                                 assembly.Save ();
 740
 741                         if (host == null)
 742                                 return null;
 743
 744                         //
 745                         // Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
 746                         // work from MethodBuilders.   Retarded, I know.
 747                         //
 748                         var tt = assembly.Builder.GetType (tb.Name);
 749                         MethodInfo mi = tt.GetMethod (mb.Name);
 750
 751                         // Pull the FieldInfos from the type, and keep track of them
 752                         foreach (Field field in queued_fields){
 753                                 FieldInfo fi = tt.GetField (field.Name);
 754
 755                                 Tuple<FieldSpec, FieldInfo> old;
 756
 757                                 // If a previous value was set, nullify it, so that we do
 758                                 // not leak memory
 759                                 if (fields.TryGetValue (field.Name, out old)) {
 760                                         if (old.Item1.MemberType.IsStruct) {
 761                                                 //
 762                                                 // TODO: Clear fields for structs
 763                                                 //
 764                                         } else {
 765                                                 try {
 766                                                         old.Item2.SetValue (null, null);
 767                                                 } catch {
 768                                                 }
 769                                         }
 770
 771                                         fields [field.Name] = Tuple.Create (old.Item1, fi);
 772                                 } else {
 773                                         fields.Add (field.Name, Tuple.Create (field.Spec, fi));
 774                                 }
 775                         }
 776                         //types.Add (tb);
 777
 778                         queued_fields.Clear ();
 779
 780                         return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
 781                 }
 782 #endif
 783                 static internal void LoadAliases (NamespaceEntry ns)
 784                 {
 785                         ns.Populate (using_alias_list, using_list);
 786                 }
 787
 788                 /// <summary>
 789                 ///   A sentinel value used to indicate that no value was
 790                 ///   was set by the compiled function.   This is used to
 791                 ///   differentiate between a function not returning a
 792                 ///   value and null.
 793                 /// </summary>
 794                 public class NoValueSet {
 795                 }
 796
 797                 static internal Tuple<FieldSpec, FieldInfo> LookupField (string name)
 798                 {
 799                         Tuple<FieldSpec, FieldInfo> fi;
 800                         fields.TryGetValue (name, out fi);
 801                         return fi;
 802                 }
 803
 804                 //
 805                 // Puts the FieldBuilder into a queue of names that will be
 806                 // registered.   We can not register FieldBuilders directly
 807                 // we need to fetch the FieldInfo after Reflection cooks the
 808                 // types, or bad things happen (bad means: FieldBuilders behave
 809                 // incorrectly across multiple assemblies, causing assignments to
 810                 // invalid areas
 811                 //
 812                 // This also serves for the parser to register Field classes
 813                 // that should be exposed as global variables
 814                 //
 815                 static internal void QueueField (Field f)
 816                 {
 817                         queued_fields.Add (f);
 818                 }
 819
 820                 static string Quote (string s)
 821                 {
 822                         if (s.IndexOf ('"') != -1)
 823                                 s = s.Replace ("\"", "\\\"");
 824
 825                         return "\"" + s + "\"";
 826                 }
 827
 828                 static public string GetUsing ()
 829                 {
 830                         lock (evaluator_lock){
 831                                 StringBuilder sb = new StringBuilder ();
 832
 833                                 foreach (object x in using_alias_list)
 834                                         sb.Append (String.Format ("using {0};\n", x));
 835
 836                                 foreach (object x in using_list)
 837                                         sb.Append (String.Format ("using {0};\n", x));
 838
 839                                 return sb.ToString ();
 840                         }
 841                 }
 842
 843                 static internal ICollection<string> GetUsingList ()
 844                 {
 845                         var res = new List<string> (using_list.Count);
 846                         foreach (object ue in using_list)
 847                                 res.Add (ue.ToString ());
 848                         return res;
 849                 }
 850
 851                 static internal string [] GetVarNames ()
 852                 {
 853                         lock (evaluator_lock){
 854                                 return new List<string> (fields.Keys).ToArray ();
 855                         }
 856                 }
 857
 858                 static public string GetVars ()
 859                 {
 860                         lock (evaluator_lock){
 861                                 StringBuilder sb = new StringBuilder ();
 862
 863                                 foreach (var de in fields){
 864                                         var fi = LookupField (de.Key);
 865                                         object value;
 866                                         try {
 867                                                 value = fi.Item2.GetValue (null);
 868                                                 if (value is string)
 869                                                         value = Quote ((string)value);
 870                                         } catch {
 871                                                 value = "<error reading value>";
 872                                         }
 873
 874                                         sb.AppendFormat ("{0} {1} = {2}", fi.Item1.MemberType.GetSignatureForError (), de.Key, value);
 875                                         sb.AppendLine ();
 876                                 }
 877
 878                                 return sb.ToString ();
 879                         }
 880                 }
 881
 882                 /// <summary>
 883                 ///    Loads the given assembly and exposes the API to the user.
 884                 /// </summary>
 885                 static public void LoadAssembly (string file)
 886                 {
 887                         lock (evaluator_lock){
 888                                 var a = loader.LoadAssemblyFile (file);
 889                                 if (a != null)
 890                                         loader.Importer.ImportAssembly (a, RootContext.ToplevelTypes.GlobalRootNamespace);
 891                         }
 892                 }
 893
 894                 /// <summary>
 895                 ///    Exposes the API of the given assembly to the Evaluator
 896                 /// </summary>
 897                 static public void ReferenceAssembly (Assembly a)
 898                 {
 899                         lock (evaluator_lock){
 900                                 loader.Importer.ImportAssembly (a, RootContext.ToplevelTypes.GlobalRootNamespace);
 901                         }
 902                 }
 903
 904                 /// <summary>
 905                 ///   If true, turns type expressions into valid expressions
 906                 ///   and calls the describe method on it
 907                 /// </summary>
 908                 public static bool DescribeTypeExpressions;
 909         }
 910
 911
 912         /// <summary>
 913         ///   A delegate that can be used to invoke the
 914         ///   compiled expression or statement.
 915         /// </summary>
 916         /// <remarks>
 917         ///   Since the Compile methods will compile
 918         ///   statements and expressions into the same
 919         ///   delegate, you can tell if a value was returned
 920         ///   by checking whether the returned value is of type
 921         ///   NoValueSet.
 922         /// </remarks>
 923
 924         public delegate void CompiledMethod (ref object retvalue);
 925
 926         /// <summary>
 927         ///   The default base class for every interaction line
 928         /// </summary>
 929         /// <remarks>
 930         ///   The expressions and statements behave as if they were
 931         ///   a static method of this class.   The InteractiveBase class
 932         ///   contains a number of useful methods, but can be overwritten
 933         ///   by setting the InteractiveBaseType property in the Evaluator
 934         /// </remarks>
 935         public class InteractiveBase {
 936                 /// <summary>
 937                 ///   Determines where the standard output of methods in this class will go.
 938                 /// </summary>
 939                 public static TextWriter Output = Console.Out;
 940
 941                 /// <summary>
 942                 ///   Determines where the standard error of methods in this class will go.
 943                 /// </summary>
 944                 public static TextWriter Error = Console.Error;
 945
 946                 /// <summary>
 947                 ///   The primary prompt used for interactive use.
 948                 /// </summary>
 949                 public static string Prompt             = "csharp> ";
 950
 951                 /// <summary>
 952                 ///   The secondary prompt used for interactive use (used when
 953                 ///   an expression is incomplete).
 954                 /// </summary>
 955                 public static string ContinuationPrompt = "      > ";
 956
 957                 /// <summary>
 958                 ///   Used to signal that the user has invoked the  `quit' statement.
 959                 /// </summary>
 960                 public static bool QuitRequested;
 961
 962                 /// <summary>
 963                 ///   Shows all the variables defined so far.
 964                 /// </summary>
 965                 static public void ShowVars ()
 966                 {
 967                         Output.Write (Evaluator.GetVars ());
 968                         Output.Flush ();
 969                 }
 970
 971                 /// <summary>
 972                 ///   Displays the using statements in effect at this point.
 973                 /// </summary>
 974                 static public void ShowUsing ()
 975                 {
 976                         Output.Write (Evaluator.GetUsing ());
 977                         Output.Flush ();
 978                 }
 979
 980                 public delegate void Simple ();
 981
 982                 /// <summary>
 983                 ///   Times the execution of the given delegate
 984                 /// </summary>
 985                 static public TimeSpan Time (Simple a)
 986                 {
 987                         DateTime start = DateTime.Now;
 988                         a ();
 989                         return DateTime.Now - start;
 990                 }
 991
 992 #if !SMCS_SOURCE && !STATIC
 993                 /// <summary>
 994                 ///   Loads the assemblies from a package
 995                 /// </summary>
 996                 /// <remarks>
 997                 ///   Loads the assemblies from a package.   This is equivalent
 998                 ///   to passing the -pkg: command line flag to the C# compiler
 999                 ///   on the command line.
1000                 /// </remarks>
1001                 static public void LoadPackage (string pkg)
1002                 {
1003                         if (pkg == null){
1004                                 Error.WriteLine ("Invalid package specified");
1005                                 return;
1006                         }
1007
1008                         string pkgout = Driver.GetPackageFlags (pkg, false, RootContext.ToplevelTypes.Compiler.Report);
1009                         if (pkgout == null)
1010                                 return;
1011
1012                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
1013                                 Split (new Char [] { ' ', '\t'});
1014
1015                         foreach (string s in xargs){
1016                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
1017                                         string lib = s.Substring (s.IndexOf (':')+1);
1018
1019                                         Evaluator.LoadAssembly (lib);
1020                                         continue;
1021                                 }
1022                         }
1023                 }
1024 #endif
1025
1026 #if !STATIC
1027                 /// <summary>
1028                 ///   Loads the assembly
1029                 /// </summary>
1030                 /// <remarks>
1031                 ///   Loads the specified assembly and makes its types
1032                 ///   available to the evaluator.  This is equivalent
1033                 ///   to passing the -pkg: command line flag to the C#
1034                 ///   compiler on the command line.
1035                 /// </remarks>
1036                 static public void LoadAssembly (string assembly)
1037                 {
1038                         Evaluator.LoadAssembly (assembly);
1039                 }
1040 #endif
1041
1042                 /// <summary>
1043                 ///   Returns a list of available static methods.
1044                 /// </summary>
1045                 static public string help {
1046                         get {
1047                                 return "Static methods:\n" +
1048                                         "  Describe (object)       - Describes the object's type\n" +
1049                                         "  LoadPackage (package);  - Loads the given Package (like -pkg:FILE)\n" +
1050                                         "  LoadAssembly (assembly) - Loads the given assembly (like -r:ASSEMBLY)\n" +
1051                                         "  ShowVars ();            - Shows defined local variables.\n" +
1052                                         "  ShowUsing ();           - Show active using declarations.\n" +
1053                                         "  Prompt                  - The prompt used by the C# shell\n" +
1054                                         "  ContinuationPrompt      - The prompt for partial input\n" +
1055                                         "  Time(() -> { })         - Times the specified code\n" +
1056                                         "  quit;                   - You'll never believe it - this quits the repl!\n" +
1057                                         "  help;                   - This help text\n";
1058                         }
1059                 }
1060
1061                 /// <summary>
1062                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1063                 /// </summary>
1064                 static public object quit {
1065                         get {
1066                                 QuitRequested = true;
1067
1068                                 // To avoid print null at the exit
1069                                 return typeof (Evaluator.NoValueSet);
1070                         }
1071                 }
1072
1073 #if !NET_2_1
1074                 /// <summary>
1075                 ///   Describes an object or a type.
1076                 /// </summary>
1077                 /// <remarks>
1078                 ///   This method will show a textual representation
1079                 ///   of the object's type.  If the object is a
1080                 ///   System.Type it renders the type directly,
1081                 ///   otherwise it renders the type returned by
1082                 ///   invoking GetType on the object.
1083                 /// </remarks>
1084                 static public string Describe (object x)
1085                 {
1086                         if (x == null)
1087                                 return "<null>";
1088
1089                         var type = x as Type ?? x.GetType ();
1090
1091                         StringWriter sw = new StringWriter ();
1092                         new Outline (type, sw, true, false, false).OutlineType ();
1093                         return sw.ToString ();
1094                 }
1095 #endif
1096         }
1097
1098         class HoistedEvaluatorVariable : HoistedVariable
1099         {
1100                 public HoistedEvaluatorVariable (Field field)
1101                         : base (null, field)
1102                 {
1103                 }
1104
1105                 public override void EmitSymbolInfo ()
1106                 {
1107                 }
1108
1109                 protected override FieldExpr GetFieldExpression (EmitContext ec)
1110                 {
1111                         return new FieldExpr (field, field.Location);
1112                 }
1113         }
1114
1115         /// <summary>
1116         ///    A class used to assign values if the source expression is not void
1117         ///
1118         ///    Used by the interactive shell to allow it to call this code to set
1119         ///    the return value for an invocation.
1120         /// </summary>
1121         class OptionalAssign : SimpleAssign {
1122                 public OptionalAssign (Expression t, Expression s, Location loc)
1123                         : base (t, s, loc)
1124                 {
1125                 }
1126
1127                 protected override Expression DoResolve (ResolveContext ec)
1128                 {
1129                         CloneContext cc = new CloneContext ();
1130                         Expression clone = source.Clone (cc);
1131
1132                         //
1133                         // A useful feature for the REPL: if we can resolve the expression
1134                         // as a type, Describe the type;
1135                         //
1136                         if (Evaluator.DescribeTypeExpressions){
1137                                 var old_printer = Evaluator.SetPrinter (new StreamReportPrinter (TextWriter.Null));
1138                                 clone = clone.Resolve (ec);
1139                                 if (clone == null){
1140                                         clone = source.Clone (cc);
1141                                         clone = clone.Resolve (ec, ResolveFlags.Type);
1142                                         if (clone == null){
1143                                                 Evaluator.SetPrinter (old_printer);
1144                                                 clone = source.Clone (cc);
1145                                                 clone = clone.Resolve (ec);
1146                                                 return null;
1147                                         }
1148
1149                                         Arguments args = new Arguments (1);
1150                                         args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
1151                                         source = new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
1152                                 }
1153                                 Evaluator.SetPrinter (old_printer);
1154                         } else {
1155                                 clone = clone.Resolve (ec);
1156                                 if (clone == null)
1157                                         return null;
1158                         }
1159
1160                         // This means its really a statement.
1161                         if (clone.Type == TypeManager.void_type || clone is DynamicInvocation || clone is Assign) {
1162                                 return clone;
1163                         }
1164
1165                         return base.DoResolve (ec);
1166                 }
1167         }
1168
1169         public class Undo {
1170                 List<KeyValuePair<TypeContainer, TypeContainer>> undo_types;
1171
1172                 public Undo ()
1173                 {
1174                         undo_types = new List<KeyValuePair<TypeContainer, TypeContainer>> ();
1175                 }
1176
1177                 public void AddTypeContainer (TypeContainer current_container, TypeContainer tc)
1178                 {
1179                         if (current_container == tc){
1180                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1181                                 return;
1182                         }
1183
1184                         if (undo_types == null)
1185                                 undo_types = new List<KeyValuePair<TypeContainer, TypeContainer>> ();
1186
1187                         undo_types.Add (new KeyValuePair<TypeContainer, TypeContainer> (current_container, tc));
1188                 }
1189
1190                 public void ExecuteUndo ()
1191                 {
1192                         if (undo_types == null)
1193                                 return;
1194
1195                         foreach (var p in undo_types){
1196                                 TypeContainer current_container = p.Key;
1197
1198                                 current_container.RemoveTypeContainer (p.Value);
1199                         }
1200                         undo_types = null;
1201                 }
1202         }
1203
1204 }