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 using System;
  13 using System.Threading;
  14 using System.Collections;
  15 using System.Reflection;
  16 using System.Reflection.Emit;
  17 using System.IO;
  18 using System.Globalization;
  19 using System.Text;
  20
  21 namespace Mono.CSharp {
  22
  23         /// <summary>
  24         ///   Evaluator: provides an API to evaluate C# statements and
  25         ///   expressions dynamically.
  26         /// </summary>
  27         /// <remarks>
  28         ///   This class exposes static methods to evaluate expressions in the
  29         ///   current program.
  30         ///
  31         ///   To initialize the evaluator with a number of compiler
  32         ///   options call the Init(string[]args) method with a set of
  33         ///   command line options that the compiler recognizes.
  34         ///
  35         ///   To interrupt execution of a statement, you can invoke the
  36         ///   Evaluator.Interrupt method.
  37         /// </remarks>
  38         public class Evaluator {
  39
  40                 enum ParseMode {
  41                         // Parse silently, do not output any error messages
  42                         Silent,
  43
  44                         // Report errors during parse
  45                         ReportErrors,
  46
  47                         // Auto-complete, means that the tokenizer will start producing
  48                         // GETCOMPLETIONS tokens when it reaches a certain point.
  49                         GetCompletions
  50                 }
  51
  52                 static object evaluator_lock = new object ();
  53
  54                 static string current_debug_name;
  55                 static int count;
  56                 static Thread invoke_thread;
  57
  58                 static ArrayList using_alias_list = new ArrayList ();
  59                 internal static ArrayList using_list = new ArrayList ();
  60                 static Hashtable fields = new Hashtable ();
  61
  62                 static Type   interactive_base_class = typeof (InteractiveBase);
  63                 static Driver driver;
  64                 static bool inited;
  65
  66                 static CompilerContext ctx;
  67
  68                 public static TextWriter MessageOutput = Console.Out;
  69
  70                 /// <summary>
  71                 ///   Optional initialization for the Evaluator.
  72                 /// </summary>
  73                 /// <remarks>
  74                 ///  Initializes the Evaluator with the command line options
  75                 ///  that would be processed by the command line compiler.  Only
  76                 ///  the first call to Init will work, any future invocations are
  77                 ///  ignored.
  78                 ///
  79                 ///  You can safely avoid calling this method if your application
  80                 ///  does not need any of the features exposed by the command line
  81                 ///  interface.
  82                 /// </remarks>
  83                 public static void Init (string [] args)
  84                 {
  85                         InitAndGetStartupFiles (args);
  86                 }
  87
  88
  89                 /// <summary>
  90                 ///   Optional initialization for the Evaluator.
  91                 /// </summary>
  92                 /// <remarks>
  93                 ///  Initializes the Evaluator with the command line
  94                 ///  options that would be processed by the command
  95                 ///  line compiler.  Only the first call to
  96                 ///  InitAndGetStartupFiles or Init will work, any future
  97                 ///  invocations are ignored.
  98                 ///
  99                 ///  You can safely avoid calling this method if your application
 100                 ///  does not need any of the features exposed by the command line
 101                 ///  interface.
 102                 ///
 103                 ///  This method return an array of strings that contains any
 104                 ///  files that were specified in `args'.
 105                 /// </remarks>
 106                 public static string [] InitAndGetStartupFiles (string [] args)
 107                 {
 108                         lock (evaluator_lock){
 109                                 if (inited)
 110                                         return new string [0];
 111
 112                                 driver = Driver.Create (args, false, new ConsoleReportPrinter ());
 113                                 if (driver == null)
 114                                         throw new Exception ("Failed to create compiler driver with the given arguments");
 115
 116                                 RootContext.ToplevelTypes = new ModuleCompiled (ctx, true);
 117
 118                                 driver.ProcessDefaultConfig ();
 119
 120                                 ArrayList startup_files = new ArrayList ();
 121                                 foreach (CompilationUnit file in Location.SourceFiles)
 122                                         startup_files.Add (file.Path);
 123
 124                                 CompilerCallableEntryPoint.Reset ();
 125                                 RootContext.ToplevelTypes = new ModuleCompiled (ctx, true);
 126
 127                                 driver.LoadReferences ();
 128                                 RootContext.EvalMode = true;
 129                                 inited = true;
 130
 131                                 return (string []) startup_files.ToArray (typeof (string));
 132                         }
 133                 }
 134
 135                 static void Init ()
 136                 {
 137                         Init (new string [0]);
 138                 }
 139
 140                 static void Reset ()
 141                 {
 142                         CompilerCallableEntryPoint.PartialReset ();
 143
 144                         // Workaround for API limitation where full message printer cannot be passed
 145                         ReportPrinter printer = MessageOutput == Console.Out || MessageOutput == Console.Error ?
 146                                 new ConsoleReportPrinter (MessageOutput) :
 147                                 new StreamReportPrinter (MessageOutput);
 148
 149                         ctx = new CompilerContext (new Report (printer));
 150                         RootContext.ToplevelTypes = new ModuleCompiled (ctx, true);
 151
 152                         //
 153                         // PartialReset should not reset the core types, this is very redundant.
 154                         //
 155                         if (!TypeManager.InitCoreTypes (ctx))
 156                                 throw new Exception ("Failed to InitCoreTypes");
 157                         TypeManager.InitOptionalCoreTypes (ctx);
 158
 159                         Location.AddFile (null, "{interactive}");
 160                         Location.Initialize ();
 161
 162                         current_debug_name = "interactive" + (count++) + ".dll";
 163                         if (Environment.GetEnvironmentVariable ("SAVE") != null){
 164                                 CodeGen.Init (current_debug_name, current_debug_name, false, ctx);
 165                         } else
 166                                 CodeGen.InitDynamic (ctx, current_debug_name);
 167                 }
 168
 169                 /// <summary>
 170                 ///   The base class for the classes that host the user generated code
 171                 /// </summary>
 172                 /// <remarks>
 173                 ///
 174                 ///   This is the base class that will host the code
 175                 ///   executed by the Evaluator.  By default
 176                 ///   this is the Mono.CSharp.InteractiveBase class
 177                 ///   which is useful for interactive use.
 178                 ///
 179                 ///   By changing this property you can control the
 180                 ///   base class and the static members that are
 181                 ///   available to your evaluated code.
 182                 /// </remarks>
 183                 static public Type InteractiveBaseClass {
 184                         get {
 185                                 return interactive_base_class;
 186                         }
 187
 188                         set {
 189                                 if (value == null)
 190                                         throw new ArgumentNullException ();
 191
 192                                 lock (evaluator_lock)
 193                                         interactive_base_class = value;
 194                         }
 195                 }
 196
 197                 /// <summary>
 198                 ///   Interrupts the evaluation of an expression executing in Evaluate.
 199                 /// </summary>
 200                 /// <remarks>
 201                 ///   Use this method to interrupt long-running invocations.
 202                 /// </remarks>
 203                 public static void Interrupt ()
 204                 {
 205                         if (!inited || !invoking)
 206                                 return;
 207
 208                         if (invoke_thread != null)
 209                                 invoke_thread.Abort ();
 210                 }
 211
 212                 /// <summary>
 213                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 214                 /// </summary>
 215                 /// <remarks>
 216                 ///
 217                 ///   Compiles the input string as a C# expression or
 218                 ///   statement, unlike the Evaluate method, the
 219                 ///   resulting delegate can be invoked multiple times
 220                 ///   without incurring in the compilation overhead.
 221                 ///
 222                 ///   If the return value of this function is null,
 223                 ///   this indicates that the parsing was complete.
 224                 ///   If the return value is a string it indicates
 225                 ///   that the input string was partial and that the
 226                 ///   invoking code should provide more code before
 227                 ///   the code can be successfully compiled.
 228                 ///
 229                 ///   If you know that you will always get full expressions or
 230                 ///   statements and do not care about partial input, you can use
 231                 ///   the other Compile overload.
 232                 ///
 233                 ///   On success, in addition to returning null, the
 234                 ///   compiled parameter will be set to the delegate
 235                 ///   that can be invoked to execute the code.
 236                 ///
 237                 /// </remarks>
 238                 static public string Compile (string input, out CompiledMethod compiled)
 239                 {
 240                         if (input == null || input.Length == 0){
 241                                 compiled = null;
 242                                 return null;
 243                         }
 244
 245                         lock (evaluator_lock){
 246                                 if (!inited)
 247                                         Init ();
 248
 249                                 bool partial_input;
 250                                 CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
 251                                 if (parser == null){
 252                                         compiled = null;
 253                                         if (partial_input)
 254                                                 return input;
 255
 256                                         ParseString (ParseMode.ReportErrors, input, out partial_input);
 257                                         return null;
 258                                 }
 259
 260                                 object parser_result = parser.InteractiveResult;
 261
 262                                 if (!(parser_result is Class)){
 263                                         int errors = ctx.Report.Errors;
 264
 265                                         NamespaceEntry.VerifyAllUsing ();
 266                                         if (errors == ctx.Report.Errors)
 267                                                 parser.CurrentNamespace.Extract (using_alias_list, using_list);
 268                                 }
 269
 270                                 compiled = CompileBlock (parser_result as Class, parser.undo, ctx.Report);
 271                         }
 272
 273                         return null;
 274                 }
 275
 276                 /// <summary>
 277                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 278                 /// </summary>
 279                 /// <remarks>
 280                 ///
 281                 ///   Compiles the input string as a C# expression or
 282                 ///   statement, unlike the Evaluate method, the
 283                 ///   resulting delegate can be invoked multiple times
 284                 ///   without incurring in the compilation overhead.
 285                 ///
 286                 ///   This method can only deal with fully formed input
 287                 ///   strings and does not provide a completion mechanism.
 288                 ///   If you must deal with partial input (for example for
 289                 ///   interactive use) use the other overload.
 290                 ///
 291                 ///   On success, a delegate is returned that can be used
 292                 ///   to invoke the method.
 293                 ///
 294                 /// </remarks>
 295                 static public CompiledMethod Compile (string input)
 296                 {
 297                         CompiledMethod compiled;
 298
 299                         // Ignore partial inputs
 300                         if (Compile (input, out compiled) != null){
 301                                 // Error, the input was partial.
 302                                 return null;
 303                         }
 304
 305                         // Either null (on error) or the compiled method.
 306                         return compiled;
 307                 }
 308
 309                 //
 310                 // Todo: Should we handle errors, or expect the calling code to setup
 311                 // the recording themselves?
 312                 //
 313
 314                 /// <summary>
 315                 ///   Evaluates and expression or statement and returns any result values.
 316                 /// </summary>
 317                 /// <remarks>
 318                 ///   Evaluates the input string as a C# expression or
 319                 ///   statement.  If the input string is an expression
 320                 ///   the result will be stored in the result variable
 321                 ///   and the result_set variable will be set to true.
 322                 ///
 323                 ///   It is necessary to use the result/result_set
 324                 ///   pair to identify when a result was set (for
 325                 ///   example, execution of user-provided input can be
 326                 ///   an expression, a statement or others, and
 327                 ///   result_set would only be set if the input was an
 328                 ///   expression.
 329                 ///
 330                 ///   If the return value of this function is null,
 331                 ///   this indicates that the parsing was complete.
 332                 ///   If the return value is a string, it indicates
 333                 ///   that the input is partial and that the user
 334                 ///   should provide an updated string.
 335                 /// </remarks>
 336                 public static string Evaluate (string input, out object result, out bool result_set)
 337                 {
 338                         CompiledMethod compiled;
 339
 340                         result_set = false;
 341                         result = null;
 342
 343                         input = Compile (input, out compiled);
 344                         if (input != null)
 345                                 return input;
 346
 347                         if (compiled == null)
 348                                 return null;
 349
 350                         //
 351                         // The code execution does not need to keep the compiler lock
 352                         //
 353                         object retval = typeof (NoValueSet);
 354
 355                         try {
 356                                 invoke_thread = System.Threading.Thread.CurrentThread;
 357                                 invoking = true;
 358                                 compiled (ref retval);
 359                         } catch (ThreadAbortException e){
 360                                 Thread.ResetAbort ();
 361                                 Console.WriteLine ("Interrupted!\n{0}", e);
 362                         } finally {
 363                                 invoking = false;
 364                         }
 365
 366                         //
 367                         // We use a reference to a compiler type, in this case
 368                         // Driver as a flag to indicate that this was a statement
 369                         //
 370                         if (retval != typeof (NoValueSet)){
 371                                 result_set = true;
 372                                 result = retval;
 373                         }
 374
 375                         return null;
 376                 }
 377
 378                 public static string [] GetCompletions (string input, out string prefix)
 379                 {
 380                         prefix = "";
 381                         if (input == null || input.Length == 0)
 382                                 return null;
 383
 384                         lock (evaluator_lock){
 385                                 if (!inited)
 386                                         Init ();
 387
 388                                 bool partial_input;
 389                                 CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
 390                                 if (parser == null){
 391                                         if (CSharpParser.yacc_verbose_flag != 0)
 392                                                 Console.WriteLine ("DEBUG: No completions available");
 393                                         return null;
 394                                 }
 395
 396                                 Class parser_result = parser.InteractiveResult as Class;
 397
 398                                 if (parser_result == null){
 399                                         if (CSharpParser.yacc_verbose_flag != 0)
 400                                                 Console.WriteLine ("Do not know how to cope with !Class yet");
 401                                         return null;
 402                                 }
 403
 404                                 try {
 405                                         RootContext.ResolveTree ();
 406                                         if (ctx.Report.Errors != 0)
 407                                                 return null;
 408
 409                                         RootContext.PopulateTypes ();
 410                                         if (ctx.Report.Errors != 0)
 411                                                 return null;
 412
 413                                         MethodOrOperator method = null;
 414                                         foreach (MemberCore member in parser_result.Methods){
 415                                                 if (member.Name != "Host")
 416                                                         continue;
 417
 418                                                 method = (MethodOrOperator) member;
 419                                                 break;
 420                                         }
 421                                         if (method == null)
 422                                                 throw new InternalErrorException ("did not find the the Host method");
 423
 424                                         BlockContext bc = new BlockContext (method, method.Block, method.ReturnType);
 425
 426                                         try {
 427                                                 method.Block.Resolve (null, bc, method.ParameterInfo, method);
 428                                         } catch (CompletionResult cr){
 429                                                 prefix = cr.BaseText;
 430                                                 return cr.Result;
 431                                         }
 432                                 } finally {
 433                                         parser.undo.ExecuteUndo ();
 434                                 }
 435
 436                         }
 437                         return null;
 438                 }
 439
 440                 /// <summary>
 441                 ///   Executes the given expression or statement.
 442                 /// </summary>
 443                 /// <remarks>
 444                 ///    Executes the provided statement, returns true
 445                 ///    on success, false on parsing errors.  Exceptions
 446                 ///    might be thrown by the called code.
 447                 /// </remarks>
 448                 public static bool Run (string statement)
 449                 {
 450                         if (!inited)
 451                                 Init ();
 452
 453                         object result;
 454                         bool result_set;
 455
 456                         bool ok = Evaluate (statement, out result, out result_set) == null;
 457
 458                         return ok;
 459                 }
 460
 461                 /// <summary>
 462                 ///   Evaluates and expression or statement and returns the result.
 463                 /// </summary>
 464                 /// <remarks>
 465                 ///   Evaluates the input string as a C# expression or
 466                 ///   statement and returns the value.
 467                 ///
 468                 ///   This method will throw an exception if there is a syntax error,
 469                 ///   of if the provided input is not an expression but a statement.
 470                 /// </remarks>
 471                 public static object Evaluate (string input)
 472                 {
 473                         object result;
 474                         bool result_set;
 475
 476                         string r = Evaluate (input, out result, out result_set);
 477
 478                         if (r != null)
 479                                 throw new ArgumentException ("Syntax error on input: partial input");
 480
 481                         if (result_set == false)
 482                                 throw new ArgumentException ("The expression did not set a result");
 483
 484                         return result;
 485                 }
 486
 487                 enum InputKind {
 488                         EOF,
 489                         StatementOrExpression,
 490                         CompilationUnit,
 491                         Error
 492                 }
 493
 494                 //
 495                 // Deambiguates the input string to determine if we
 496                 // want to process a statement or if we want to
 497                 // process a compilation unit.
 498                 //
 499                 // This is done using a top-down predictive parser,
 500                 // since the yacc/jay parser can not deambiguage this
 501                 // without more than one lookahead token.   There are very
 502                 // few ambiguities.
 503                 //
 504                 static InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 505                 {
 506                         Tokenizer tokenizer = new Tokenizer (seekable, (CompilationUnit) Location.SourceFiles [0], ctx);
 507
 508                         int t = tokenizer.token ();
 509                         switch (t){
 510                         case Token.EOF:
 511                                 return InputKind.EOF;
 512
 513                         // These are toplevels
 514                         case Token.EXTERN:
 515                         case Token.OPEN_BRACKET:
 516                         case Token.ABSTRACT:
 517                         case Token.CLASS:
 518                         case Token.ENUM:
 519                         case Token.INTERFACE:
 520                         case Token.INTERNAL:
 521                         case Token.NAMESPACE:
 522                         case Token.PRIVATE:
 523                         case Token.PROTECTED:
 524                         case Token.PUBLIC:
 525                         case Token.SEALED:
 526                         case Token.STATIC:
 527                         case Token.STRUCT:
 528                                 return InputKind.CompilationUnit;
 529
 530                         // Definitely expression
 531                         case Token.FIXED:
 532                         case Token.BOOL:
 533                         case Token.BYTE:
 534                         case Token.CHAR:
 535                         case Token.DECIMAL:
 536                         case Token.DOUBLE:
 537                         case Token.FLOAT:
 538                         case Token.INT:
 539                         case Token.LONG:
 540                         case Token.NEW:
 541                         case Token.OBJECT:
 542                         case Token.SBYTE:
 543                         case Token.SHORT:
 544                         case Token.STRING:
 545                         case Token.UINT:
 546                         case Token.ULONG:
 547                                 return InputKind.StatementOrExpression;
 548
 549                         // These need deambiguation help
 550                         case Token.USING:
 551                                 t = tokenizer.token ();
 552                                 if (t == Token.EOF)
 553                                         return InputKind.EOF;
 554
 555                                 if (t == Token.IDENTIFIER)
 556                                         return InputKind.CompilationUnit;
 557                                 return InputKind.StatementOrExpression;
 558
 559
 560                         // Distinguish between:
 561                         //    delegate opt_anonymous_method_signature block
 562                         //    delegate type
 563                         case Token.DELEGATE:
 564                                 t = tokenizer.token ();
 565                                 if (t == Token.EOF)
 566                                         return InputKind.EOF;
 567                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 568                                         return InputKind.StatementOrExpression;
 569                                 return InputKind.CompilationUnit;
 570
 571                         // Distinguih between:
 572                         //    unsafe block
 573                         //    unsafe as modifier of a type declaration
 574                         case Token.UNSAFE:
 575                                 t = tokenizer.token ();
 576                                 if (t == Token.EOF)
 577                                         return InputKind.EOF;
 578                                 if (t == Token.OPEN_PARENS)
 579                                         return InputKind.StatementOrExpression;
 580                                 return InputKind.CompilationUnit;
 581
 582                         // These are errors: we list explicitly what we had
 583                         // from the grammar, ERROR and then everything else
 584
 585                         case Token.READONLY:
 586                         case Token.OVERRIDE:
 587                         case Token.ERROR:
 588                                 return InputKind.Error;
 589
 590                         // This catches everything else allowed by
 591                         // expressions.  We could add one-by-one use cases
 592                         // if needed.
 593                         default:
 594                                 return InputKind.StatementOrExpression;
 595                         }
 596                 }
 597
 598                 //
 599                 // Parses the string @input and returns a CSharpParser if succeeful.
 600                 //
 601                 // if @silent is set to true then no errors are
 602                 // reported to the user.  This is used to do various calls to the
 603                 // parser and check if the expression is parsable.
 604                 //
 605                 // @partial_input: if @silent is true, then it returns whether the
 606                 // parsed expression was partial, and more data is needed
 607                 //
 608                 static CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 609                 {
 610                         partial_input = false;
 611                         Reset ();
 612                         queued_fields.Clear ();
 613
 614                         Stream s = new MemoryStream (Encoding.Default.GetBytes (input));
 615                         SeekableStreamReader seekable = new SeekableStreamReader (s, Encoding.Default);
 616
 617                         InputKind kind = ToplevelOrStatement (seekable);
 618                         if (kind == InputKind.Error){
 619                                 if (mode == ParseMode.ReportErrors)
 620                                         ctx.Report.Error (-25, "Detection Parsing Error");
 621                                 partial_input = false;
 622                                 return null;
 623                         }
 624
 625                         if (kind == InputKind.EOF){
 626                                 if (mode == ParseMode.ReportErrors)
 627                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 628                                 partial_input = true;
 629                                 return null;
 630
 631                         }
 632                         seekable.Position = 0;
 633
 634                         CSharpParser parser = new CSharpParser (seekable, (CompilationUnit) Location.SourceFiles [0], ctx);
 635
 636                         if (kind == InputKind.StatementOrExpression){
 637                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 638                                 RootContext.StatementMode = true;
 639                         } else {
 640                                 //
 641                                 // Do not activate EvalCompilationUnitParserCharacter until
 642                                 // I have figured out all the limitations to invoke methods
 643                                 // in the generated classes.  See repl.txt
 644                                 //
 645                                 parser.Lexer.putback_char = Tokenizer.EvalUsingDeclarationsParserCharacter;
 646                                 //parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 647                                 RootContext.StatementMode = false;
 648                         }
 649
 650                         if (mode == ParseMode.GetCompletions)
 651                                 parser.Lexer.CompleteOnEOF = true;
 652
 653                         bool disable_error_reporting;
 654                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions) && CSharpParser.yacc_verbose_flag == 0)
 655                                 disable_error_reporting = true;
 656                         else
 657                                 disable_error_reporting = false;
 658
 659                         if (disable_error_reporting)
 660                                 ctx.Report.DisableReporting ();
 661                         try {
 662                                 parser.parse ();
 663                         } finally {
 664                                 if (ctx.Report.Errors != 0){
 665                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 666                                                 partial_input = true;
 667
 668                                         parser.undo.ExecuteUndo ();
 669                                         parser = null;
 670                                 }
 671
 672                                 if (disable_error_reporting)
 673                                         ctx.Report.EnableReporting ();
 674                         }
 675                         return parser;
 676                 }
 677
 678                 //
 679                 // Queue all the fields that we use, as we need to then go from FieldBuilder to FieldInfo
 680                 // or reflection gets confused (it basically gets confused, and variables override each
 681                 // other).
 682                 //
 683                 static ArrayList queued_fields = new ArrayList ();
 684
 685                 //static ArrayList types = new ArrayList ();
 686
 687                 static volatile bool invoking;
 688
 689                 static CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
 690                 {
 691                         RootContext.ResolveTree ();
 692                         if (Report.Errors != 0){
 693                                 undo.ExecuteUndo ();
 694                                 return null;
 695                         }
 696
 697                         RootContext.PopulateTypes ();
 698
 699                         if (Report.Errors != 0){
 700                                 undo.ExecuteUndo ();
 701                                 return null;
 702                         }
 703
 704                         TypeBuilder tb = null;
 705                         MethodBuilder mb = null;
 706
 707                         if (host != null){
 708                                 tb = host.TypeBuilder;
 709                                 mb = null;
 710                                 foreach (MemberCore member in host.Methods){
 711                                         if (member.Name != "Host")
 712                                                 continue;
 713
 714                                         MethodOrOperator method = (MethodOrOperator) member;
 715                                         mb = method.MethodBuilder;
 716                                         break;
 717                                 }
 718
 719                                 if (mb == null)
 720                                         throw new Exception ("Internal error: did not find the method builder for the generated method");
 721                         }
 722
 723                         RootContext.EmitCode ();
 724                         if (Report.Errors != 0)
 725                                 return null;
 726
 727                         RootContext.CloseTypes ();
 728
 729                         if (Environment.GetEnvironmentVariable ("SAVE") != null)
 730                                 CodeGen.Save (current_debug_name, false, Report);
 731
 732                         if (host == null)
 733                                 return null;
 734
 735                         //
 736                         // Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
 737                         // work from MethodBuilders.   Retarded, I know.
 738                         //
 739                         Type tt = CodeGen.Assembly.Builder.GetType (tb.Name);
 740                         MethodInfo mi = tt.GetMethod (mb.Name);
 741
 742                         // Pull the FieldInfos from the type, and keep track of them
 743                         foreach (Field field in queued_fields){
 744                                 FieldInfo fi = tt.GetField (field.Name);
 745
 746                                 FieldInfo old = (FieldInfo) fields [field.Name];
 747
 748                                 // If a previous value was set, nullify it, so that we do
 749                                 // not leak memory
 750                                 if (old != null){
 751                                         if (TypeManager.IsStruct (old.FieldType)){
 752                                                 //
 753                                                 // TODO: Clear fields for structs
 754                                                 //
 755                                         } else {
 756                                                 try {
 757                                                         old.SetValue (null, null);
 758                                                 } catch {
 759                                                 }
 760                                         }
 761                                 }
 762
 763                                 fields [field.Name] = fi;
 764                         }
 765                         //types.Add (tb);
 766
 767                         queued_fields.Clear ();
 768
 769                         return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
 770                 }
 771
 772                 static internal void LoadAliases (NamespaceEntry ns)
 773                 {
 774                         ns.Populate (using_alias_list, using_list);
 775                 }
 776
 777                 /// <summary>
 778                 ///   A sentinel value used to indicate that no value was
 779                 ///   was set by the compiled function.   This is used to
 780                 ///   differentiate between a function not returning a
 781                 ///   value and null.
 782                 /// </summary>
 783                 public class NoValueSet {
 784                 }
 785
 786                 static internal FieldInfo LookupField (string name)
 787                 {
 788                         FieldInfo fi =  (FieldInfo) fields [name];
 789
 790                         return fi;
 791                 }
 792
 793                 //
 794                 // Puts the FieldBuilder into a queue of names that will be
 795                 // registered.   We can not register FieldBuilders directly
 796                 // we need to fetch the FieldInfo after Reflection cooks the
 797                 // types, or bad things happen (bad means: FieldBuilders behave
 798                 // incorrectly across multiple assemblies, causing assignments to
 799                 // invalid areas
 800                 //
 801                 // This also serves for the parser to register Field classes
 802                 // that should be exposed as global variables
 803                 //
 804                 static internal void QueueField (Field f)
 805                 {
 806                         queued_fields.Add (f);
 807                 }
 808
 809                 static string Quote (string s)
 810                 {
 811                         if (s.IndexOf ('"') != -1)
 812                                 s = s.Replace ("\"", "\\\"");
 813
 814                         return "\"" + s + "\"";
 815                 }
 816
 817                 static public string GetUsing ()
 818                 {
 819                         lock (evaluator_lock){
 820                                 StringBuilder sb = new StringBuilder ();
 821
 822                                 foreach (object x in using_alias_list)
 823                                         sb.Append (String.Format ("using {0};\n", x));
 824
 825                                 foreach (object x in using_list)
 826                                         sb.Append (String.Format ("using {0};\n", x));
 827
 828                                 return sb.ToString ();
 829                         }
 830                 }
 831
 832                 static internal ICollection GetUsingList ()
 833                 {
 834                         ArrayList res = new ArrayList (using_list.Count);
 835                         foreach (object ue in using_list)
 836                                 res.Add (ue.ToString ());
 837                         return res;
 838                 }
 839
 840                 static internal string [] GetVarNames ()
 841                 {
 842                         lock (evaluator_lock){
 843                                 return (string []) new ArrayList (fields.Keys).ToArray (typeof (string));
 844                         }
 845                 }
 846
 847                 static public string GetVars ()
 848                 {
 849                         lock (evaluator_lock){
 850                                 StringBuilder sb = new StringBuilder ();
 851
 852                                 foreach (DictionaryEntry de in fields){
 853                                         FieldInfo fi = LookupField ((string) de.Key);
 854                                         object value = null;
 855                                         bool error = false;
 856
 857                                         try {
 858                                                 if (value == null)
 859                                                         value = "null";
 860                                                 value = fi.GetValue (null);
 861                                                 if (value is string)
 862                                                         value = Quote ((string)value);
 863                                         } catch {
 864                                                 error = true;
 865                                         }
 866
 867                                         if (error)
 868                                                 sb.Append (String.Format ("{0} {1} <error reading value>", TypeManager.CSharpName(fi.FieldType), de.Key));
 869                                         else
 870                                                 sb.Append (String.Format ("{0} {1} = {2}", TypeManager.CSharpName(fi.FieldType), de.Key, value));
 871                                 }
 872
 873                                 return sb.ToString ();
 874                         }
 875                 }
 876
 877                 /// <summary>
 878                 ///    Loads the given assembly and exposes the API to the user.
 879                 /// </summary>
 880                 static public void LoadAssembly (string file)
 881                 {
 882                         lock (evaluator_lock){
 883                                 driver.LoadAssembly (file, false);
 884                                 GlobalRootNamespace.Instance.ComputeNamespaces (ctx);
 885                         }
 886                 }
 887
 888                 /// <summary>
 889                 ///    Exposes the API of the given assembly to the Evaluator
 890                 /// </summary>
 891                 static public void ReferenceAssembly (Assembly a)
 892                 {
 893                         lock (evaluator_lock){
 894                                 GlobalRootNamespace.Instance.AddAssemblyReference (a);
 895                                 GlobalRootNamespace.Instance.ComputeNamespaces (ctx);
 896                         }
 897                 }
 898
 899         }
 900
 901
 902         /// <summary>
 903         ///   A delegate that can be used to invoke the
 904         ///   compiled expression or statement.
 905         /// </summary>
 906         /// <remarks>
 907         ///   Since the Compile methods will compile
 908         ///   statements and expressions into the same
 909         ///   delegate, you can tell if a value was returned
 910         ///   by checking whether the returned value is of type
 911         ///   NoValueSet.
 912         /// </remarks>
 913
 914         public delegate void CompiledMethod (ref object retvalue);
 915
 916         /// <summary>
 917         ///   The default base class for every interaction line
 918         /// </summary>
 919         /// <remarks>
 920         ///   The expressions and statements behave as if they were
 921         ///   a static method of this class.   The InteractiveBase class
 922         ///   contains a number of useful methods, but can be overwritten
 923         ///   by setting the InteractiveBaseType property in the Evaluator
 924         /// </remarks>
 925         public class InteractiveBase {
 926                 /// <summary>
 927                 ///   Determines where the standard output of methods in this class will go.
 928                 /// </summary>
 929                 public static TextWriter Output = Console.Out;
 930
 931                 /// <summary>
 932                 ///   Determines where the standard error of methods in this class will go.
 933                 /// </summary>
 934                 public static TextWriter Error = Console.Error;
 935
 936                 /// <summary>
 937                 ///   The primary prompt used for interactive use.
 938                 /// </summary>
 939                 public static string Prompt             = "csharp> ";
 940
 941                 /// <summary>
 942                 ///   The secondary prompt used for interactive use (used when
 943                 ///   an expression is incomplete).
 944                 /// </summary>
 945                 public static string ContinuationPrompt = "      > ";
 946
 947                 /// <summary>
 948                 ///   Used to signal that the user has invoked the  `quit' statement.
 949                 /// </summary>
 950                 public static bool QuitRequested;
 951
 952                 /// <summary>
 953                 ///   Shows all the variables defined so far.
 954                 /// </summary>
 955                 static public void ShowVars ()
 956                 {
 957                         Output.Write (Evaluator.GetVars ());
 958                         Output.Flush ();
 959                 }
 960
 961                 /// <summary>
 962                 ///   Displays the using statements in effect at this point.
 963                 /// </summary>
 964                 static public void ShowUsing ()
 965                 {
 966                         Output.Write (Evaluator.GetUsing ());
 967                         Output.Flush ();
 968                 }
 969
 970                 public delegate void Simple ();
 971
 972                 /// <summary>
 973                 ///   Times the execution of the given delegate
 974                 /// </summary>
 975                 static public TimeSpan Time (Simple a)
 976                 {
 977                         DateTime start = DateTime.Now;
 978                         a ();
 979                         return DateTime.Now - start;
 980                 }
 981
 982 #if !SMCS_SOURCE
 983                 /// <summary>
 984                 ///   Loads the assemblies from a package
 985                 /// </summary>
 986                 /// <remarks>
 987                 ///   Loads the assemblies from a package.   This is equivalent
 988                 ///   to passing the -pkg: command line flag to the C# compiler
 989                 ///   on the command line.
 990                 /// </remarks>
 991                 static public void LoadPackage (string pkg)
 992                 {
 993                         if (pkg == null){
 994                                 Error.WriteLine ("Invalid package specified");
 995                                 return;
 996                         }
 997
 998                         string pkgout = Driver.GetPackageFlags (pkg, false, RootContext.ToplevelTypes.Compiler.Report);
 999                         if (pkgout == null)
1000                                 return;
1001
1002                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
1003                                 Split (new Char [] { ' ', '\t'});
1004
1005                         foreach (string s in xargs){
1006                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
1007                                         string lib = s.Substring (s.IndexOf (':')+1);
1008
1009                                         Evaluator.LoadAssembly (lib);
1010                                         continue;
1011                                 }
1012                         }
1013                 }
1014 #endif
1015
1016                 /// <summary>
1017                 ///   Loads the assembly
1018                 /// </summary>
1019                 /// <remarks>
1020                 ///   Loads the specified assembly and makes its types
1021                 ///   available to the evaluator.  This is equivalent
1022                 ///   to passing the -pkg: command line flag to the C#
1023                 ///   compiler on the command line.
1024                 /// </remarks>
1025                 static public void LoadAssembly (string assembly)
1026                 {
1027                         Evaluator.LoadAssembly (assembly);
1028                 }
1029
1030                 /// <summary>
1031                 ///   Returns a list of available static methods.
1032                 /// </summary>
1033                 static public string help {
1034                         get {
1035                                 return  "Static methods:\n"+
1036                                         "  Describe(obj)      - Describes the object's type\n" +
1037                                         "  LoadPackage (pkg); - Loads the given Package (like -pkg:FILE)\n" +
1038                                         "  LoadAssembly (ass) - Loads the given assembly (like -r:ASS)\n" +
1039                                         "  ShowVars ();       - Shows defined local variables.\n" +
1040                                         "  ShowUsing ();      - Show active using decltions.\n" +
1041                                         "  Prompt             - The prompt used by the C# shell\n" +
1042                                         "  ContinuationPrompt - The prompt for partial input\n" +
1043                                         "  Time(() -> { })    - Times the specified code\n" +
1044                                         "  quit;\n" +
1045                                         "  help;\n";
1046                         }
1047                 }
1048
1049                 /// <summary>
1050                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1051                 /// </summary>
1052                 static public object quit {
1053                         get {
1054                                 QuitRequested = true;
1055                                 return null;
1056                         }
1057                 }
1058
1059 #if !NET_2_1
1060                 /// <summary>
1061                 ///   Describes an object or a type.
1062                 /// </summary>
1063                 /// <remarks>
1064                 ///   This method will show a textual representation
1065                 ///   of the object's type.  If the object is a
1066                 ///   System.Type it renders the type directly,
1067                 ///   otherwise it renders the type returned by
1068                 ///   invoking GetType on the object.
1069                 /// </remarks>
1070                 static public string Describe (object x)
1071                 {
1072                         if (x == null)
1073                                 return "";
1074
1075                         Type t = x as Type;
1076                         if (t == null)
1077                                 t = x.GetType ();
1078
1079                         StringWriter sw = new StringWriter ();
1080                         new Outline (t, sw, true, false, false).OutlineType ();
1081                         return sw.ToString ();
1082                 }
1083 #endif
1084         }
1085
1086         //
1087         // A local variable reference that will create a Field in a
1088         // Class with the resolved type.  This is necessary so we can
1089         // support "var" as a field type in a class declaration.
1090         //
1091         // We allow LocalVariableReferece to do the heavy lifting, and
1092         // then we insert the field with the resolved type
1093         //
1094         public class LocalVariableReferenceWithClassSideEffect : LocalVariableReference {
1095                 TypeContainer container;
1096                 string name;
1097
1098                 public LocalVariableReferenceWithClassSideEffect (TypeContainer container, string name, Block current_block, string local_variable_id, LocalInfo li, Location loc)
1099                         : base (current_block, local_variable_id, loc, li, false)
1100                 {
1101                         this.container = container;
1102                         this.name = name;
1103                 }
1104
1105                 public override bool Equals (object obj)
1106                 {
1107                         LocalVariableReferenceWithClassSideEffect lvr = obj as LocalVariableReferenceWithClassSideEffect;
1108                         if (lvr == null)
1109                                 return false;
1110
1111                         if (lvr.name != name || lvr.container != container)
1112                                 return false;
1113
1114                         return base.Equals (obj);
1115                 }
1116
1117                 public override int GetHashCode ()
1118                 {
1119                         return name.GetHashCode ();
1120                 }
1121
1122                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
1123                 {
1124                         Expression ret = base.DoResolveLValue (ec, right_side);
1125                         if (ret == null)
1126                                 return null;
1127
1128                         Field f = new Field (container, new TypeExpression (ret.Type, Location),
1129                                              Modifiers.PUBLIC | Modifiers.STATIC,
1130                                              new MemberName (name, Location), null);
1131                         container.AddField (f);
1132                         if (f.Define ())
1133                                 Evaluator.QueueField (f);
1134
1135                         return ret;
1136                 }
1137         }
1138
1139         /// <summary>
1140         ///    A class used to assign values if the source expression is not void
1141         ///
1142         ///    Used by the interactive shell to allow it to call this code to set
1143         ///    the return value for an invocation.
1144         /// </summary>
1145         class OptionalAssign : SimpleAssign {
1146                 public OptionalAssign (Expression t, Expression s, Location loc)
1147                         : base (t, s, loc)
1148                 {
1149                 }
1150
1151                 protected override Expression DoResolve (ResolveContext ec)
1152                 {
1153                         CloneContext cc = new CloneContext ();
1154                         Expression clone = source.Clone (cc);
1155
1156                         clone = clone.Resolve (ec);
1157                         if (clone == null)
1158                                 return null;
1159
1160                         // This means its really a statement.
1161                         if (clone.Type == TypeManager.void_type){
1162                                 source = source.Resolve (ec);
1163                                 target = null;
1164                                 type = TypeManager.void_type;
1165                                 eclass = ExprClass.Value;
1166                                 return this;
1167                         }
1168
1169                         return base.DoResolve (ec);
1170                 }
1171
1172                 public override void Emit (EmitContext ec)
1173                 {
1174                         if (target == null)
1175                                 source.Emit (ec);
1176                         else
1177                                 base.Emit (ec);
1178                 }
1179
1180                 public override void EmitStatement (EmitContext ec)
1181                 {
1182                         if (target == null)
1183                                 source.Emit (ec);
1184                         else
1185                                 base.EmitStatement (ec);
1186                 }
1187         }
1188
1189         public class Undo {
1190                 ArrayList undo_types;
1191
1192                 public Undo ()
1193                 {
1194                         undo_types = new ArrayList ();
1195                 }
1196
1197                 public void AddTypeContainer (TypeContainer current_container, TypeContainer tc)
1198                 {
1199                         if (current_container == tc){
1200                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1201                                 return;
1202                         }
1203
1204                         if (undo_types == null)
1205                                 undo_types = new ArrayList ();
1206                         undo_types.Add (new Pair (current_container, tc));
1207                 }
1208
1209                 public void ExecuteUndo ()
1210                 {
1211                         if (undo_types == null)
1212                                 return;
1213
1214                         foreach (Pair p in undo_types){
1215                                 TypeContainer current_container = (TypeContainer) p.First;
1216
1217                                 current_container.RemoveTypeContainer ((TypeContainer) p.Second);
1218                         }
1219                         undo_types = null;
1220                 }
1221         }
1222
1223 }
1224