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