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