mcs/mcs/eval.cs

   1 //
   2 // eval.cs: Evaluation and Hosting API for the C# compiler
   3 //
   4 // Authors:
   5 //   Miguel de Icaza (miguel@gnome.org)
   6 //
   7 // Dual licensed under the terms of the MIT X11 or GNU GPL
   8 //
   9 // Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
  10 // Copyright 2004, 2005, 2006, 2007, 2008 Novell, Inc
  11 //
  12 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                                 driver = Driver.Create (args, false);
 109                                 if (driver == null)
 110                                         throw new Exception ("Failed to create compiler driver with the given arguments");
 111
 112                                 driver.ProcessDefaultConfig ();
 113
 114                                 ArrayList startup_files = new ArrayList ();
 115                                 foreach (CompilationUnit file in Location.SourceFiles)
 116                                         startup_files.Add (file.Path);
 117
 118                                 CompilerCallableEntryPoint.Reset ();
 119                                 driver.LoadReferences ();
 120                                 RootContext.EvalMode = true;
 121                                 inited = true;
 122
 123                                 return (string []) startup_files.ToArray (typeof (string));
 124                         }
 125                 }
 126
 127                 static void Init ()
 128                 {
 129                         Init (new string [0]);
 130                 }
 131
 132                 static void Reset ()
 133                 {
 134                         CompilerCallableEntryPoint.PartialReset ();
 135
 136                         //
 137                         // PartialReset should not reset the core types, this is very redundant.
 138                         //
 139                         if (!TypeManager.InitCoreTypes ())
 140                                 throw new Exception ("Failed to InitCoreTypes");
 141                         TypeManager.InitOptionalCoreTypes ();
 142
 143                         Location.AddFile ("{interactive}");
 144                         Location.Initialize ();
 145
 146                         current_debug_name = "interactive" + (count++) + ".dll";
 147                         if (Environment.GetEnvironmentVariable ("SAVE") != null){
 148                                 CodeGen.Init (current_debug_name, current_debug_name, false);
 149                         } else
 150                                 CodeGen.InitDynamic (current_debug_name);
 151                 }
 152
 153                 /// <summary>
 154                 ///   The base class for the classes that host the user generated code
 155                 /// </summary>
 156                 /// <remarks>
 157                 ///
 158                 ///   This is the base class that will host the code
 159                 ///   executed by the Evaluator.  By default
 160                 ///   this is the Mono.CSharp.InteractiveBase class
 161                 ///   which is useful for interactive use.
 162                 ///
 163                 ///   By changing this property you can control the
 164                 ///   base class and the static members that are
 165                 ///   available to your evaluated code.
 166                 /// </remarks>
 167                 static public Type InteractiveBaseClass {
 168                         get {
 169                                 return interactive_base_class;
 170                         }
 171
 172                         set {
 173                                 if (value == null)
 174                                         throw new ArgumentNullException ();
 175
 176                                 lock (evaluator_lock)
 177                                         interactive_base_class = value;
 178                         }
 179                 }
 180
 181                 /// <summary>
 182                 ///   Interrupts the evaluation of an expression executing in Evaluate.
 183                 /// </summary>
 184                 /// <remarks>
 185                 ///   Use this method to interrupt long-running invocations.
 186                 /// </remarks>
 187                 public static void Interrupt ()
 188                 {
 189                         if (!inited || !invoking)
 190                                 return;
 191
 192                         if (invoke_thread != null)
 193                                 invoke_thread.Abort ();
 194                 }
 195
 196                 /// <summary>
 197                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 198                 /// </summary>
 199                 /// <remarks>
 200                 ///
 201                 ///   Compiles the input string as a C# expression or
 202                 ///   statement, unlike the Evaluate method, the
 203                 ///   resulting delegate can be invoked multiple times
 204                 ///   without incurring in the compilation overhead.
 205                 ///
 206                 ///   If the return value of this function is null,
 207                 ///   this indicates that the parsing was complete.
 208                 ///   If the return value is a string it indicates
 209                 ///   that the input string was partial and that the
 210                 ///   invoking code should provide more code before
 211                 ///   the code can be successfully compiled.
 212                 ///
 213                 ///   If you know that you will always get full expressions or
 214                 ///   statements and do not care about partial input, you can use
 215                 ///   the other Compile overload.
 216                 ///
 217                 ///   On success, in addition to returning null, the
 218                 ///   compiled parameter will be set to the delegate
 219                 ///   that can be invoked to execute the code.
 220                 ///
 221                 /// </remarks>
 222                 static public string Compile (string input, out CompiledMethod compiled)
 223                 {
 224                         if (input == null || input.Length == 0){
 225                                 compiled = null;
 226                                 return null;
 227                         }
 228
 229                         lock (evaluator_lock){
 230                                 if (!inited)
 231                                         Init ();
 232
 233                                 bool partial_input;
 234                                 CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
 235                                 if (parser == null){
 236                                         compiled = null;
 237                                         if (partial_input)
 238                                                 return input;
 239
 240                                         ParseString (ParseMode.ReportErrors, input, out partial_input);
 241                                         return null;
 242                                 }
 243
 244                                 object parser_result = parser.InteractiveResult;
 245
 246                                 if (!(parser_result is Class)){
 247                                         int errors = Report.Errors;
 248
 249                                         NamespaceEntry.VerifyAllUsing ();
 250                                         if (errors == Report.Errors)
 251                                                 parser.CurrentNamespace.Extract (using_alias_list, using_list);
 252                                 }
 253
 254                                 compiled = CompileBlock (parser_result as Class, parser.undo);
 255                         }
 256
 257                         return null;
 258                 }
 259
 260                 /// <summary>
 261                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 262                 /// </summary>
 263                 /// <remarks>
 264                 ///
 265                 ///   Compiles the input string as a C# expression or
 266                 ///   statement, unlike the Evaluate method, the
 267                 ///   resulting delegate can be invoked multiple times
 268                 ///   without incurring in the compilation overhead.
 269                 ///
 270                 ///   This method can only deal with fully formed input
 271                 ///   strings and does not provide a completion mechanism.
 272                 ///   If you must deal with partial input (for example for
 273                 ///   interactive use) use the other overload.
 274                 ///
 275                 ///   On success, a delegate is returned that can be used
 276                 ///   to invoke the method.
 277                 ///
 278                 /// </remarks>
 279                 static public CompiledMethod Compile (string input)
 280                 {
 281                         CompiledMethod compiled;
 282
 283                         // Ignore partial inputs
 284                         if (Compile (input, out compiled) != null){
 285                                 // Error, the input was partial.
 286                                 return null;
 287                         }
 288
 289                         // Either null (on error) or the compiled method.
 290                         return compiled;
 291                 }
 292
 293                 //
 294                 // Todo: Should we handle errors, or expect the calling code to setup
 295                 // the recording themselves?
 296                 //
 297
 298                 /// <summary>
 299                 ///   Evaluates and expression or statement and returns any result values.
 300                 /// </summary>
 301                 /// <remarks>
 302                 ///   Evaluates the input string as a C# expression or
 303                 ///   statement.  If the input string is an expression
 304                 ///   the result will be stored in the result variable
 305                 ///   and the result_set variable will be set to true.
 306                 ///
 307                 ///   It is necessary to use the result/result_set
 308                 ///   pair to identify when a result was set (for
 309                 ///   example, execution of user-provided input can be
 310                 ///   an expression, a statement or others, and
 311                 ///   result_set would only be set if the input was an
 312                 ///   expression.
 313                 ///
 314                 ///   If the return value of this function is null,
 315                 ///   this indicates that the parsing was complete.
 316                 ///   If the return value is a string, it indicates
 317                 ///   that the input is partial and that the user
 318                 ///   should provide an updated string.
 319                 /// </remarks>
 320                 public static string Evaluate (string input, out object result, out bool result_set)
 321                 {
 322                         CompiledMethod compiled;
 323
 324                         result_set = false;
 325                         result = null;
 326
 327                         input = Compile (input, out compiled);
 328                         if (input != null)
 329                                 return input;
 330
 331                         if (compiled == null)
 332                                 return null;
 333
 334                         //
 335                         // The code execution does not need to keep the compiler lock
 336                         //
 337                         object retval = typeof (NoValueSet);
 338
 339                         try {
 340                                 invoke_thread = System.Threading.Thread.CurrentThread;
 341                                 invoking = true;
 342                                 compiled (ref retval);
 343                         } catch (ThreadAbortException e){
 344                                 Thread.ResetAbort ();
 345                                 Console.WriteLine ("Interrupted!\n{0}", e);
 346                         } finally {
 347                                 invoking = false;
 348                         }
 349
 350                         //
 351                         // We use a reference to a compiler type, in this case
 352                         // Driver as a flag to indicate that this was a statement
 353                         //
 354                         if (retval != typeof (NoValueSet)){
 355                                 result_set = true;
 356                                 result = retval;
 357                         }
 358
 359                         return null;
 360                 }
 361
 362                 public static string [] GetCompletions (string input, out string prefix)
 363                 {
 364                         prefix = "";
 365                         if (input == null || input.Length == 0)
 366                                 return null;
 367
 368                         lock (evaluator_lock){
 369                                 if (!inited)
 370                                         Init ();
 371
 372                                 bool partial_input;
 373                                 CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
 374                                 if (parser == null){
 375                                         if (CSharpParser.yacc_verbose_flag != 0)
 376                                                 Console.WriteLine ("DEBUG: No completions available");
 377                                         return null;
 378                                 }
 379
 380                                 Class parser_result = parser.InteractiveResult as Class;
 381
 382                                 if (parser_result == null){
 383                                         if (CSharpParser.yacc_verbose_flag != 0)
 384                                                 Console.WriteLine ("Do not know how to cope with !Class yet");
 385                                         return null;
 386                                 }
 387
 388                                 try {
 389                                         RootContext.ResolveTree ();
 390                                         if (Report.Errors != 0)
 391                                                 return null;
 392
 393                                         RootContext.PopulateTypes ();
 394                                         if (Report.Errors != 0)
 395                                                 return null;
 396
 397                                         MethodOrOperator method = null;
 398                                         foreach (MemberCore member in parser_result.Methods){
 399                                                 if (member.Name != "Host")
 400                                                         continue;
 401
 402                                                 method = (MethodOrOperator) member;
 403                                                 break;
 404                                         }
 405                                         if (method == null)
 406                                                 throw new InternalErrorException ("did not find the the Host method");
 407
 408                                         BlockContext bc = new BlockContext (method, method.Block, method.ReturnType);
 409
 410                                         try {
 411                                                 method.Block.Resolve (null, bc, method.ParameterInfo, method);
 412                                         } catch (CompletionResult cr){
 413                                                 prefix = cr.BaseText;
 414                                                 return cr.Result;
 415                                         }
 416                                 } finally {
 417                                         parser.undo.ExecuteUndo ();
 418                                 }
 419
 420                         }
 421                         return null;
 422                 }
 423
 424                 /// <summary>
 425                 ///   Executes the given expression or statement.
 426                 /// </summary>
 427                 /// <remarks>
 428                 ///    Executes the provided statement, returns true
 429                 ///    on success, false on parsing errors.  Exceptions
 430                 ///    might be thrown by the called code.
 431                 /// </remarks>
 432                 public static bool Run (string statement)
 433                 {
 434                         if (!inited)
 435                                 Init ();
 436
 437                         object result;
 438                         bool result_set;
 439
 440                         bool ok = Evaluate (statement, out result, out result_set) == null;
 441
 442                         return ok;
 443                 }
 444
 445                 /// <summary>
 446                 ///   Evaluates and expression or statement and returns the result.
 447                 /// </summary>
 448                 /// <remarks>
 449                 ///   Evaluates the input string as a C# expression or
 450                 ///   statement and returns the value.
 451                 ///
 452                 ///   This method will throw an exception if there is a syntax error,
 453                 ///   of if the provided input is not an expression but a statement.
 454                 /// </remarks>
 455                 public static object Evaluate (string input)
 456                 {
 457                         object result;
 458                         bool result_set;
 459
 460                         string r = Evaluate (input, out result, out result_set);
 461
 462                         if (r != null)
 463                                 throw new ArgumentException ("Syntax error on input: partial input");
 464
 465                         if (result_set == false)
 466                                 throw new ArgumentException ("The expression did not set a result");
 467
 468                         return result;
 469                 }
 470
 471                 enum InputKind {
 472                         EOF,
 473                         StatementOrExpression,
 474                         CompilationUnit,
 475                         Error
 476                 }
 477
 478                 //
 479                 // Deambiguates the input string to determine if we
 480                 // want to process a statement or if we want to
 481                 // process a compilation unit.
 482                 //
 483                 // This is done using a top-down predictive parser,
 484                 // since the yacc/jay parser can not deambiguage this
 485                 // without more than one lookahead token.   There are very
 486                 // few ambiguities.
 487                 //
 488                 static InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 489                 {
 490                         Tokenizer tokenizer = new Tokenizer (seekable, (CompilationUnit) Location.SourceFiles [0]);
 491
 492                         int t = tokenizer.token ();
 493                         switch (t){
 494                         case Token.EOF:
 495                                 return InputKind.EOF;
 496
 497                         // These are toplevels
 498                         case Token.EXTERN:
 499                         case Token.OPEN_BRACKET:
 500                         case Token.ABSTRACT:
 501                         case Token.CLASS:
 502                         case Token.ENUM:
 503                         case Token.INTERFACE:
 504                         case Token.INTERNAL:
 505                         case Token.NAMESPACE:
 506                         case Token.PRIVATE:
 507                         case Token.PROTECTED:
 508                         case Token.PUBLIC:
 509                         case Token.SEALED:
 510                         case Token.STATIC:
 511                         case Token.STRUCT:
 512                                 return InputKind.CompilationUnit;
 513
 514                         // Definitely expression
 515                         case Token.FIXED:
 516                         case Token.BOOL:
 517                         case Token.BYTE:
 518                         case Token.CHAR:
 519                         case Token.DECIMAL:
 520                         case Token.DOUBLE:
 521                         case Token.FLOAT:
 522                         case Token.INT:
 523                         case Token.LONG:
 524                         case Token.NEW:
 525                         case Token.OBJECT:
 526                         case Token.SBYTE:
 527                         case Token.SHORT:
 528                         case Token.STRING:
 529                         case Token.UINT:
 530                         case Token.ULONG:
 531                                 return InputKind.StatementOrExpression;
 532
 533                         // These need deambiguation help
 534                         case Token.USING:
 535                                 t = tokenizer.token ();
 536                                 if (t == Token.EOF)
 537                                         return InputKind.EOF;
 538
 539                                 if (t == Token.IDENTIFIER)
 540                                         return InputKind.CompilationUnit;
 541                                 return InputKind.StatementOrExpression;
 542
 543
 544                         // Distinguish between:
 545                         //    delegate opt_anonymous_method_signature block
 546                         //    delegate type
 547                         case Token.DELEGATE:
 548                                 t = tokenizer.token ();
 549                                 if (t == Token.EOF)
 550                                         return InputKind.EOF;
 551                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 552                                         return InputKind.StatementOrExpression;
 553                                 return InputKind.CompilationUnit;
 554
 555                         // Distinguih between:
 556                         //    unsafe block
 557                         //    unsafe as modifier of a type declaration
 558                         case Token.UNSAFE:
 559                                 t = tokenizer.token ();
 560                                 if (t == Token.EOF)
 561                                         return InputKind.EOF;
 562                                 if (t == Token.OPEN_PARENS)
 563                                         return InputKind.StatementOrExpression;
 564                                 return InputKind.CompilationUnit;
 565
 566                         // These are errors: we list explicitly what we had
 567                         // from the grammar, ERROR and then everything else
 568
 569                         case Token.READONLY:
 570                         case Token.OVERRIDE:
 571                         case Token.ERROR:
 572                                 return InputKind.Error;
 573
 574                         // This catches everything else allowed by
 575                         // expressions.  We could add one-by-one use cases
 576                         // if needed.
 577                         default:
 578                                 return InputKind.StatementOrExpression;
 579                         }
 580                 }
 581
 582                 //
 583                 // Parses the string @input and returns a CSharpParser if succeeful.
 584                 //
 585                 // if @silent is set to true then no errors are
 586                 // reported to the user.  This is used to do various calls to the
 587                 // parser and check if the expression is parsable.
 588                 //
 589                 // @partial_input: if @silent is true, then it returns whether the
 590                 // parsed expression was partial, and more data is needed
 591                 //
 592                 static CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 593                 {
 594                         partial_input = false;
 595                         Reset ();
 596                         queued_fields.Clear ();
 597
 598                         Stream s = new MemoryStream (Encoding.Default.GetBytes (input));
 599                         SeekableStreamReader seekable = new SeekableStreamReader (s, Encoding.Default);
 600
 601                         InputKind kind = ToplevelOrStatement (seekable);
 602                         if (kind == InputKind.Error){
 603                                 if (mode == ParseMode.ReportErrors)
 604                                         Report.Error (-25, "Detection Parsing Error");
 605                                 partial_input = false;
 606                                 return null;
 607                         }
 608
 609                         if (kind == InputKind.EOF){
 610                                 if (mode == ParseMode.ReportErrors)
 611                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 612                                 partial_input = true;
 613                                 return null;
 614
 615                         }
 616                         seekable.Position = 0;
 617
 618                         CSharpParser parser = new CSharpParser (seekable, (CompilationUnit) Location.SourceFiles [0]);
 619                         parser.ErrorOutput = Report.Stderr;
 620
 621                         if (kind == InputKind.StatementOrExpression){
 622                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 623                                 RootContext.StatementMode = true;
 624                         } else {
 625                                 //
 626                                 // Do not activate EvalCompilationUnitParserCharacter until
 627                                 // I have figured out all the limitations to invoke methods
 628                                 // in the generated classes.  See repl.txt
 629                                 //
 630                                 parser.Lexer.putback_char = Tokenizer.EvalUsingDeclarationsParserCharacter;
 631                                 //parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 632                                 RootContext.StatementMode = false;
 633                         }
 634
 635                         if (mode == ParseMode.GetCompletions)
 636                                 parser.Lexer.CompleteOnEOF = true;
 637
 638                         bool disable_error_reporting;
 639                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions) && CSharpParser.yacc_verbose_flag == 0)
 640                                 disable_error_reporting = true;
 641                         else
 642                                 disable_error_reporting = false;
 643
 644                         if (disable_error_reporting)
 645                                 Report.DisableReporting ();
 646                         try {
 647                                 parser.parse ();
 648                         } finally {
 649                                 if (Report.Errors != 0){
 650                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 651                                                 partial_input = true;
 652
 653                                         parser.undo.ExecuteUndo ();
 654                                         parser = null;
 655                                 }
 656
 657                                 if (disable_error_reporting)
 658                                         Report.EnableReporting ();
 659                         }
 660                         return parser;
 661                 }
 662
 663                 //
 664                 // Queue all the fields that we use, as we need to then go from FieldBuilder to FieldInfo
 665                 // or reflection gets confused (it basically gets confused, and variables override each
 666                 // other).
 667                 //
 668                 static ArrayList queued_fields = new ArrayList ();
 669
 670                 //static ArrayList types = new ArrayList ();
 671
 672                 static volatile bool invoking;
 673
 674                 static CompiledMethod CompileBlock (Class host, Undo undo)
 675                 {
 676                         RootContext.ResolveTree ();
 677                         if (Report.Errors != 0){
 678                                 undo.ExecuteUndo ();
 679                                 return null;
 680                         }
 681
 682                         RootContext.PopulateTypes ();
 683
 684                         if (Report.Errors != 0){
 685                                 undo.ExecuteUndo ();
 686                                 return null;
 687                         }
 688
 689                         TypeBuilder tb = null;
 690                         MethodBuilder mb = null;
 691
 692                         if (host != null){
 693                                 tb = host.TypeBuilder;
 694                                 mb = null;
 695                                 foreach (MemberCore member in host.Methods){
 696                                         if (member.Name != "Host")
 697                                                 continue;
 698
 699                                         MethodOrOperator method = (MethodOrOperator) member;
 700                                         mb = method.MethodBuilder;
 701                                         break;
 702                                 }
 703
 704                                 if (mb == null)
 705                                         throw new Exception ("Internal error: did not find the method builder for the generated method");
 706                         }
 707
 708                         RootContext.EmitCode ();
 709                         if (Report.Errors != 0)
 710                                 return null;
 711
 712                         RootContext.CloseTypes ();
 713
 714                         if (Environment.GetEnvironmentVariable ("SAVE") != null)
 715                                 CodeGen.Save (current_debug_name, false);
 716
 717                         if (host == null)
 718                                 return null;
 719
 720                         //
 721                         // Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
 722                         // work from MethodBuilders.   Retarded, I know.
 723                         //
 724                         Type tt = CodeGen.Assembly.Builder.GetType (tb.Name);
 725                         MethodInfo mi = tt.GetMethod (mb.Name);
 726
 727                         // Pull the FieldInfos from the type, and keep track of them
 728                         foreach (Field field in queued_fields){
 729                                 FieldInfo fi = tt.GetField (field.Name);
 730
 731                                 FieldInfo old = (FieldInfo) fields [field.Name];
 732
 733                                 // If a previous value was set, nullify it, so that we do
 734                                 // not leak memory
 735                                 if (old != null){
 736                                         if (TypeManager.IsStruct (old.FieldType)){
 737                                                 //
 738                                                 // TODO: Clear fields for structs
 739                                                 //
 740                                         } else {
 741                                                 try {
 742                                                         old.SetValue (null, null);
 743                                                 } catch {
 744                                                 }
 745                                         }
 746                                 }
 747
 748                                 fields [field.Name] = fi;
 749                         }
 750                         //types.Add (tb);
 751
 752                         queued_fields.Clear ();
 753
 754                         return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
 755                 }
 756
 757                 static internal void LoadAliases (NamespaceEntry ns)
 758                 {
 759                         ns.Populate (using_alias_list, using_list);
 760                 }
 761
 762                 /// <summary>
 763                 ///   A sentinel value used to indicate that no value was
 764                 ///   was set by the compiled function.   This is used to
 765                 ///   differentiate between a function not returning a
 766                 ///   value and null.
 767                 /// </summary>
 768                 public class NoValueSet {
 769                 }
 770
 771                 static internal FieldInfo LookupField (string name)
 772                 {
 773                         FieldInfo fi =  (FieldInfo) fields [name];
 774
 775                         return fi;
 776                 }
 777
 778                 //
 779                 // Puts the FieldBuilder into a queue of names that will be
 780                 // registered.   We can not register FieldBuilders directly
 781                 // we need to fetch the FieldInfo after Reflection cooks the
 782                 // types, or bad things happen (bad means: FieldBuilders behave
 783                 // incorrectly across multiple assemblies, causing assignments to
 784                 // invalid areas
 785                 //
 786                 // This also serves for the parser to register Field classes
 787                 // that should be exposed as global variables
 788                 //
 789                 static internal void QueueField (Field f)
 790                 {
 791                         queued_fields.Add (f);
 792                 }
 793
 794                 static string Quote (string s)
 795                 {
 796                         if (s.IndexOf ('"') != -1)
 797                                 s = s.Replace ("\"", "\\\"");
 798
 799                         return "\"" + s + "\"";
 800                 }
 801
 802                 static public string GetUsing ()
 803                 {
 804                         lock (evaluator_lock){
 805                                 StringBuilder sb = new StringBuilder ();
 806
 807                                 foreach (object x in using_alias_list)
 808                                         sb.Append (String.Format ("using {0};\n", x));
 809
 810                                 foreach (object x in using_list)
 811                                         sb.Append (String.Format ("using {0};\n", x));
 812
 813                                 return sb.ToString ();
 814                         }
 815                 }
 816
 817                 static internal ICollection GetUsingList ()
 818                 {
 819                         ArrayList res = new ArrayList (using_list.Count);
 820                         foreach (object ue in using_list)
 821                                 res.Add (ue.ToString ());
 822                         return res;
 823                 }
 824
 825                 static internal string [] GetVarNames ()
 826                 {
 827                         lock (evaluator_lock){
 828                                 return (string []) new ArrayList (fields.Keys).ToArray (typeof (string));
 829                         }
 830                 }
 831
 832                 static public string GetVars ()
 833                 {
 834                         lock (evaluator_lock){
 835                                 StringBuilder sb = new StringBuilder ();
 836
 837                                 foreach (DictionaryEntry de in fields){
 838                                         FieldInfo fi = LookupField ((string) de.Key);
 839                                         object value = null;
 840                                         bool error = false;
 841
 842                                         try {
 843                                                 if (value == null)
 844                                                         value = "null";
 845                                                 value = fi.GetValue (null);
 846                                                 if (value is string)
 847                                                         value = Quote ((string)value);
 848                                         } catch {
 849                                                 error = true;
 850                                         }
 851
 852                                         if (error)
 853                                                 sb.Append (String.Format ("{0} {1} <error reading value>", TypeManager.CSharpName(fi.FieldType), de.Key));
 854                                         else
 855                                                 sb.Append (String.Format ("{0} {1} = {2}", TypeManager.CSharpName(fi.FieldType), de.Key, value));
 856                                 }
 857
 858                                 return sb.ToString ();
 859                         }
 860                 }
 861
 862                 /// <summary>
 863                 ///    Loads the given assembly and exposes the API to the user.
 864                 /// </summary>
 865                 static public void LoadAssembly (string file)
 866                 {
 867                         lock (evaluator_lock){
 868                                 Driver.LoadAssembly (file, false);
 869                                 GlobalRootNamespace.Instance.ComputeNamespaces ();
 870                         }
 871                 }
 872
 873                 /// <summary>
 874                 ///    Exposes the API of the given assembly to the Evaluator
 875                 /// </summary>
 876                 static public void ReferenceAssembly (Assembly a)
 877                 {
 878                         lock (evaluator_lock){
 879                                 GlobalRootNamespace.Instance.AddAssemblyReference (a);
 880                                 GlobalRootNamespace.Instance.ComputeNamespaces ();
 881                         }
 882                 }
 883
 884         }
 885
 886
 887         /// <summary>
 888         ///   A delegate that can be used to invoke the
 889         ///   compiled expression or statement.
 890         /// </summary>
 891         /// <remarks>
 892         ///   Since the Compile methods will compile
 893         ///   statements and expressions into the same
 894         ///   delegate, you can tell if a value was returned
 895         ///   by checking whether the returned value is of type
 896         ///   NoValueSet.
 897         /// </remarks>
 898
 899         public delegate void CompiledMethod (ref object retvalue);
 900
 901         /// <summary>
 902         ///   The default base class for every interaction line
 903         /// </summary>
 904         /// <remarks>
 905         ///   The expressions and statements behave as if they were
 906         ///   a static method of this class.   The InteractiveBase class
 907         ///   contains a number of useful methods, but can be overwritten
 908         ///   by setting the InteractiveBaseType property in the Evaluator
 909         /// </remarks>
 910         public class InteractiveBase {
 911                 /// <summary>
 912                 ///   Determines where the standard output of methods in this class will go.
 913                 /// </summary>
 914                 public static TextWriter Output = Console.Out;
 915
 916                 /// <summary>
 917                 ///   Determines where the standard error of methods in this class will go.
 918                 /// </summary>
 919                 public static TextWriter Error = Console.Error;
 920
 921                 /// <summary>
 922                 ///   The primary prompt used for interactive use.
 923                 /// </summary>
 924                 public static string Prompt             = "csharp> ";
 925
 926                 /// <summary>
 927                 ///   The secondary prompt used for interactive use (used when
 928                 ///   an expression is incomplete).
 929                 /// </summary>
 930                 public static string ContinuationPrompt = "      > ";
 931
 932                 /// <summary>
 933                 ///   Used to signal that the user has invoked the  `quit' statement.
 934                 /// </summary>
 935                 public static bool QuitRequested;
 936
 937                 /// <summary>
 938                 ///   Shows all the variables defined so far.
 939                 /// </summary>
 940                 static public void ShowVars ()
 941                 {
 942                         Output.Write (Evaluator.GetVars ());
 943                         Output.Flush ();
 944                 }
 945
 946                 /// <summary>
 947                 ///   Displays the using statements in effect at this point.
 948                 /// </summary>
 949                 static public void ShowUsing ()
 950                 {
 951                         Output.Write (Evaluator.GetUsing ());
 952                         Output.Flush ();
 953                 }
 954
 955                 public delegate void Simple ();
 956
 957                 /// <summary>
 958                 ///   Times the execution of the given delegate
 959                 /// </summary>
 960                 static public TimeSpan Time (Simple a)
 961                 {
 962                         DateTime start = DateTime.Now;
 963                         a ();
 964                         return DateTime.Now - start;
 965                 }
 966
 967 #if !SMCS_SOURCE
 968                 /// <summary>
 969                 ///   Loads the assemblies from a package
 970                 /// </summary>
 971                 /// <remarks>
 972                 ///   Loads the assemblies from a package.   This is equivalent
 973                 ///   to passing the -pkg: command line flag to the C# compiler
 974                 ///   on the command line.
 975                 /// </remarks>
 976                 static public void LoadPackage (string pkg)
 977                 {
 978                         if (pkg == null){
 979                                 Error.WriteLine ("Invalid package specified");
 980                                 return;
 981                         }
 982
 983                         string pkgout = Driver.GetPackageFlags (pkg, false);
 984                         if (pkgout == null)
 985                                 return;
 986
 987                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
 988                                 Split (new Char [] { ' ', '\t'});
 989
 990                         foreach (string s in xargs){
 991                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
 992                                         string lib = s.Substring (s.IndexOf (':')+1);
 993
 994                                         Evaluator.LoadAssembly (lib);
 995                                         continue;
 996                                 }
 997                         }
 998                 }
 999 #endif
1000
1001                 /// <summary>
1002                 ///   Loads the assembly
1003                 /// </summary>
1004                 /// <remarks>
1005                 ///   Loads the specified assembly and makes its types
1006                 ///   available to the evaluator.  This is equivalent
1007                 ///   to passing the -pkg: command line flag to the C#
1008                 ///   compiler on the command line.
1009                 /// </remarks>
1010                 static public void LoadAssembly (string assembly)
1011                 {
1012                         Evaluator.LoadAssembly (assembly);
1013                 }
1014
1015                 /// <summary>
1016                 ///   Returns a list of available static methods.
1017                 /// </summary>
1018                 static public string help {
1019                         get {
1020                                 return  "Static methods:\n"+
1021                                         "  Describe(obj)      - Describes the object's type\n" +
1022                                         "  LoadPackage (pkg); - Loads the given Package (like -pkg:FILE)\n" +
1023                                         "  LoadAssembly (ass) - Loads the given assembly (like -r:ASS)\n" +
1024                                         "  ShowVars ();       - Shows defined local variables.\n" +
1025                                         "  ShowUsing ();      - Show active using decltions.\n" +
1026                                         "  Prompt             - The prompt used by the C# shell\n" +
1027                                         "  ContinuationPrompt - The prompt for partial input\n" +
1028                                         "  Time(() -> { })    - Times the specified code\n" +
1029                                         "  quit;\n" +
1030                                         "  help;\n";
1031                         }
1032                 }
1033
1034                 /// <summary>
1035                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1036                 /// </summary>
1037                 static public object quit {
1038                         get {
1039                                 QuitRequested = true;
1040                                 return null;
1041                         }
1042                 }
1043
1044 #if !NET_2_1
1045                 /// <summary>
1046                 ///   Describes an object or a type.
1047                 /// </summary>
1048                 /// <remarks>
1049                 ///   This method will show a textual representation
1050                 ///   of the object's type.  If the object is a
1051                 ///   System.Type it renders the type directly,
1052                 ///   otherwise it renders the type returned by
1053                 ///   invoking GetType on the object.
1054                 /// </remarks>
1055                 static public string Describe (object x)
1056                 {
1057                         if (x == null)
1058                                 return "";
1059
1060                         Type t = x as Type;
1061                         if (t == null)
1062                                 t = x.GetType ();
1063
1064                         StringWriter sw = new StringWriter ();
1065                         new Outline (t, sw, true, false, false).OutlineType ();
1066                         return sw.ToString ();
1067                 }
1068 #endif
1069         }
1070
1071         //
1072         // A local variable reference that will create a Field in a
1073         // Class with the resolved type.  This is necessary so we can
1074         // support "var" as a field type in a class declaration.
1075         //
1076         // We allow LocalVariableReferece to do the heavy lifting, and
1077         // then we insert the field with the resolved type
1078         //
1079         public class LocalVariableReferenceWithClassSideEffect : LocalVariableReference {
1080                 TypeContainer container;
1081                 string name;
1082
1083                 public LocalVariableReferenceWithClassSideEffect (TypeContainer container, string name, Block current_block, string local_variable_id, LocalInfo li, Location loc)
1084                         : base (current_block, local_variable_id, loc, li, false)
1085                 {
1086                         this.container = container;
1087                         this.name = name;
1088                 }
1089
1090                 public override bool Equals (object obj)
1091                 {
1092                         LocalVariableReferenceWithClassSideEffect lvr = obj as LocalVariableReferenceWithClassSideEffect;
1093                         if (lvr == null)
1094                                 return false;
1095
1096                         if (lvr.name != name || lvr.container != container)
1097                                 return false;
1098
1099                         return base.Equals (obj);
1100                 }
1101
1102                 public override int GetHashCode ()
1103                 {
1104                         return name.GetHashCode ();
1105                 }
1106
1107                 override public Expression DoResolveLValue (ResolveContext ec, Expression right_side)
1108                 {
1109                         Expression ret = base.DoResolveLValue (ec, right_side);
1110                         if (ret == null)
1111                                 return null;
1112
1113                         Field f = new Field (container, new TypeExpression (ret.Type, Location),
1114                                              Modifiers.PUBLIC | Modifiers.STATIC,
1115                                              new MemberName (name, Location), null);
1116                         container.AddField (f);
1117                         if (f.Define ())
1118                                 Evaluator.QueueField (f);
1119
1120                         return ret;
1121                 }
1122         }
1123
1124         /// <summary>
1125         ///    A class used to assign values if the source expression is not void
1126         ///
1127         ///    Used by the interactive shell to allow it to call this code to set
1128         ///    the return value for an invocation.
1129         /// </summary>
1130         class OptionalAssign : SimpleAssign {
1131                 public OptionalAssign (Expression t, Expression s, Location loc)
1132                         : base (t, s, loc)
1133                 {
1134                 }
1135
1136                 public override Expression DoResolve (ResolveContext ec)
1137                 {
1138                         CloneContext cc = new CloneContext ();
1139                         Expression clone = source.Clone (cc);
1140
1141                         clone = clone.Resolve (ec);
1142                         if (clone == null)
1143                                 return null;
1144
1145                         // This means its really a statement.
1146                         if (clone.Type == TypeManager.void_type){
1147                                 source = source.Resolve (ec);
1148                                 target = null;
1149                                 type = TypeManager.void_type;
1150                                 eclass = ExprClass.Value;
1151                                 return this;
1152                         }
1153
1154                         return base.DoResolve (ec);
1155                 }
1156
1157                 public override void Emit (EmitContext ec)
1158                 {
1159                         if (target == null)
1160                                 source.Emit (ec);
1161                         else
1162                                 base.Emit (ec);
1163                 }
1164
1165                 public override void EmitStatement (EmitContext ec)
1166                 {
1167                         if (target == null)
1168                                 source.Emit (ec);
1169                         else
1170                                 base.EmitStatement (ec);
1171                 }
1172         }
1173
1174         public class Undo {
1175                 ArrayList undo_types;
1176
1177                 public Undo ()
1178                 {
1179                         undo_types = new ArrayList ();
1180                 }
1181
1182                 public void AddTypeContainer (TypeContainer current_container, TypeContainer tc)
1183                 {
1184                         if (current_container == tc){
1185                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1186                                 return;
1187                         }
1188
1189                         if (undo_types == null)
1190                                 undo_types = new ArrayList ();
1191                         undo_types.Add (new Pair (current_container, tc));
1192                 }
1193
1194                 public void ExecuteUndo ()
1195                 {
1196                         if (undo_types == null)
1197                                 return;
1198
1199                         foreach (Pair p in undo_types){
1200                                 TypeContainer current_container = (TypeContainer) p.First;
1201
1202                                 current_container.RemoveTypeContainer ((TypeContainer) p.Second);
1203                         }
1204                         undo_types = null;
1205                 }
1206         }
1207
1208 }
1209