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 //   Marek Safar (marek.safar@gmail.com)
   7 //
   8 // Dual licensed under the terms of the MIT X11 or GNU GPL
   9 //
  10 // Copyright 2001, 2002, 2003 Ximian, Inc (http://www.ximian.com)
  11 // Copyright 2004-2011 Novell, Inc
  12 // Copyright 2011 Xamarin Inc
  13 //
  14
  15 using System;
  16 using System.Threading;
  17 using System.Collections.Generic;
  18 using System.Reflection;
  19 using System.Reflection.Emit;
  20 using System.IO;
  21 using System.Text;
  22 using System.Linq;
  23
  24 namespace Mono.CSharp
  25 {
  26
  27         /// <summary>
  28         /// Experimental!
  29         /// </summary>
  30         public delegate void ValueModificationHandler (string variableName, int row, int column, object value);
  31
  32         /// <summary>
  33         ///   Evaluator: provides an API to evaluate C# statements and
  34         ///   expressions dynamically.
  35         /// </summary>
  36         /// <remarks>
  37         ///   This class exposes static methods to evaluate expressions in the
  38         ///   current program.
  39         ///
  40         ///   To initialize the evaluator with a number of compiler
  41         ///   options call the Init(string[]args) method with a set of
  42         ///   command line options that the compiler recognizes.
  43         ///
  44         ///   To interrupt execution of a statement, you can invoke the
  45         ///   Evaluator.Interrupt method.
  46         /// </remarks>
  47         public class Evaluator {
  48
  49                 enum ParseMode {
  50                         // Parse silently, do not output any error messages
  51                         Silent,
  52
  53                         // Report errors during parse
  54                         ReportErrors,
  55
  56                         // Auto-complete, means that the tokenizer will start producing
  57                         // GETCOMPLETIONS tokens when it reaches a certain point.
  58                         GetCompletions
  59                 }
  60
  61                 static object evaluator_lock = new object ();
  62                 static volatile bool invoking;
  63
  64 #if !STATIC
  65                 static int count;
  66 #endif
  67                 static Thread invoke_thread;
  68
  69                 readonly Dictionary<string, Tuple<FieldSpec, FieldInfo>> fields;
  70
  71                 Type base_class;
  72                 bool inited;
  73                 int startup_files;
  74
  75                 readonly CompilerContext ctx;
  76                 readonly ModuleContainer module;
  77                 readonly ReflectionImporter importer;
  78                 readonly CompilationSourceFile source_file;
  79
  80                 int? listener_id;
  81
  82                 public Evaluator (CompilerContext ctx)
  83                 {
  84                         this.ctx = ctx;
  85
  86                         module = new ModuleContainer (ctx);
  87                         module.Evaluator = this;
  88
  89                         source_file = new CompilationSourceFile (module, null);
  90                         module.AddTypeContainer (source_file);
  91
  92                         startup_files = ctx.SourceFiles.Count;
  93
  94                         // FIXME: Importer needs this assembly for internalsvisibleto
  95                         module.SetDeclaringAssembly (new AssemblyDefinitionDynamic (module, "evaluator"));
  96                         importer = new ReflectionImporter (module, ctx.BuiltinTypes);
  97
  98                         InteractiveBaseClass = typeof (InteractiveBase);
  99                         fields = new Dictionary<string, Tuple<FieldSpec, FieldInfo>> ();
 100                 }
 101
 102                 void Init ()
 103                 {
 104                         var loader = new DynamicLoader (importer, ctx);
 105
 106                         CompilerCallableEntryPoint.Reset ();
 107                         RootContext.ToplevelTypes = module;
 108
 109                         //var startup_files = new List<string> ();
 110                         //foreach (CompilationUnit file in Location.SourceFiles)
 111                         //    startup_files.Add (file.Path);
 112
 113                         loader.LoadReferences (module);
 114                         ctx.BuiltinTypes.CheckDefinitions (module);
 115                         module.InitializePredefinedTypes ();
 116
 117                         inited = true;
 118                 }
 119
 120                 void ParseStartupFiles ()
 121                 {
 122                         Driver d = new Driver (ctx);
 123
 124                         Location.Initialize (ctx.SourceFiles);
 125
 126                         var parser_session = new ParserSession ();
 127                         for (int i = 0; i < startup_files; ++i) {
 128                                 var sf = ctx.SourceFiles [i];
 129                                 d.Parse (sf, module, parser_session, ctx.Report);
 130                         }
 131                 }
 132
 133                 void Reset ()
 134                 {
 135                         CompilerCallableEntryPoint.PartialReset ();
 136
 137                         Location.Reset ();
 138                         Location.Initialize (ctx.SourceFiles);
 139                 }
 140
 141                 /// <summary>
 142                 /// When set evaluator will automatically wait on Task of async methods. When not
 143                 /// set it's called responsibility to handle Task execution
 144                 /// </summary>
 145                 public bool WaitOnTask { get; set; }
 146
 147                 /// <summary>
 148                 ///   If true, turns type expressions into valid expressions
 149                 ///   and calls the describe method on it
 150                 /// </summary>
 151                 public bool DescribeTypeExpressions;
 152
 153                 /// <summary>
 154                 ///   Whether the evaluator will use terse syntax, and the semicolons at the end are optional
 155                 /// </summary>
 156                 public bool Terse = true;
 157
 158                 /// <summary>
 159                 ///   The base class for the classes that host the user generated code
 160                 /// </summary>
 161                 /// <remarks>
 162                 ///
 163                 ///   This is the base class that will host the code
 164                 ///   executed by the Evaluator.  By default
 165                 ///   this is the Mono.CSharp.InteractiveBase class
 166                 ///   which is useful for interactive use.
 167                 ///
 168                 ///   By changing this property you can control the
 169                 ///   base class and the static members that are
 170                 ///   available to your evaluated code.
 171                 /// </remarks>
 172                 public Type InteractiveBaseClass {
 173                         get {
 174                                 return base_class;
 175                         }
 176                         set {
 177                                 base_class = value;
 178
 179                                 if (value != null && typeof (InteractiveBase).IsAssignableFrom (value))
 180                                         InteractiveBase.Evaluator = this;
 181                         }
 182                 }
 183
 184                 /// <summary>
 185                 ///   Interrupts the evaluation of an expression executing in Evaluate.
 186                 /// </summary>
 187                 /// <remarks>
 188                 ///   Use this method to interrupt long-running invocations.
 189                 /// </remarks>
 190                 public void Interrupt ()
 191                 {
 192                         if (!inited || !invoking)
 193                                 return;
 194
 195                         if (invoke_thread != null)
 196                                 invoke_thread.Abort ();
 197                 }
 198
 199                 /// <summary>
 200                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 201                 /// </summary>
 202                 /// <remarks>
 203                 ///
 204                 ///   Compiles the input string as a C# expression or
 205                 ///   statement, unlike the Evaluate method, the
 206                 ///   resulting delegate can be invoked multiple times
 207                 ///   without incurring in the compilation overhead.
 208                 ///
 209                 ///   If the return value of this function is null,
 210                 ///   this indicates that the parsing was complete.
 211                 ///   If the return value is a string it indicates
 212                 ///   that the input string was partial and that the
 213                 ///   invoking code should provide more code before
 214                 ///   the code can be successfully compiled.
 215                 ///
 216                 ///   If you know that you will always get full expressions or
 217                 ///   statements and do not care about partial input, you can use
 218                 ///   the other Compile overload.
 219                 ///
 220                 ///   On success, in addition to returning null, the
 221                 ///   compiled parameter will be set to the delegate
 222                 ///   that can be invoked to execute the code.
 223                 ///
 224                 /// </remarks>
 225                 public string Compile (string input, out CompiledMethod compiled)
 226                 {
 227                         if (input == null || input.Length == 0){
 228                                 compiled = null;
 229                                 return null;
 230                         }
 231
 232                         lock (evaluator_lock){
 233                                 if (!inited) {
 234                                         Init ();
 235                                         ParseStartupFiles ();
 236                                 } else {
 237                                         ctx.Report.Printer.Reset ();
 238                                 }
 239
 240                                 bool partial_input;
 241                                 CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
 242
 243                                 // Terse mode, try to provide the trailing semicolon automatically.
 244                                 if (parser == null && Terse && partial_input){
 245                                         bool ignore;
 246
 247                                         // check if the source would compile with a block, if so, we should not
 248                                         // add the semicolon.
 249                                         var needs_block = ParseString (ParseMode.Silent, input + "{}", out ignore) != null;
 250                                         if (!needs_block)
 251                                                 parser = ParseString (ParseMode.Silent, input + ";", out ignore);
 252                                 }
 253                                 if (parser == null){
 254                                         compiled = null;
 255                                         if (partial_input)
 256                                                 return input;
 257
 258                                         ParseString (ParseMode.ReportErrors, input, out partial_input);
 259                                         return null;
 260                                 }
 261
 262                                 Class parser_result = parser.InteractiveResult;
 263                                 compiled = CompileBlock (parser_result, parser.undo, ctx.Report);
 264                                 return null;
 265                         }
 266                 }
 267
 268                 /// <summary>
 269                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 270                 /// </summary>
 271                 /// <remarks>
 272                 ///
 273                 ///   Compiles the input string as a C# expression or
 274                 ///   statement, unlike the Evaluate method, the
 275                 ///   resulting delegate can be invoked multiple times
 276                 ///   without incurring in the compilation overhead.
 277                 ///
 278                 ///   This method can only deal with fully formed input
 279                 ///   strings and does not provide a completion mechanism.
 280                 ///   If you must deal with partial input (for example for
 281                 ///   interactive use) use the other overload.
 282                 ///
 283                 ///   On success, a delegate is returned that can be used
 284                 ///   to invoke the method.
 285                 ///
 286                 /// </remarks>
 287                 public CompiledMethod Compile (string input)
 288                 {
 289                         CompiledMethod compiled;
 290
 291                         // Ignore partial inputs
 292                         if (Compile (input, out compiled) != null){
 293                                 // Error, the input was partial.
 294                                 return null;
 295                         }
 296
 297                         // Either null (on error) or the compiled method.
 298                         return compiled;
 299                 }
 300
 301                 static MethodInfo listener_proxy_value;
 302                 internal void EmitValueChangedCallback (EmitContext ec, string name, TypeSpec type, Location loc)
 303                 {
 304                         if (listener_id == null)
 305                                 listener_id = ListenerProxy.Register (ModificationListener);
 306
 307                         if (listener_proxy_value == null)
 308                                 listener_proxy_value = typeof (ListenerProxy).GetMethod ("ValueChanged");
 309
 310 #if STATIC
 311                         throw new NotSupportedException ();
 312 #else
 313                         // object value, int row, int col, string name, int listenerId
 314                         if (type.IsStructOrEnum)
 315                                 ec.Emit (OpCodes.Box, type);
 316
 317                         ec.EmitInt (loc.Row);
 318                         ec.EmitInt (loc.Column);
 319                         ec.Emit (OpCodes.Ldstr, name);
 320                         ec.EmitInt (listener_id.Value);
 321                         ec.Emit (OpCodes.Call, listener_proxy_value);
 322 #endif
 323                 }
 324
 325                 /// <summary>
 326                 ///   Evaluates and expression or statement and returns any result values.
 327                 /// </summary>
 328                 /// <remarks>
 329                 ///   Evaluates the input string as a C# expression or
 330                 ///   statement.  If the input string is an expression
 331                 ///   the result will be stored in the result variable
 332                 ///   and the result_set variable will be set to true.
 333                 ///
 334                 ///   It is necessary to use the result/result_set
 335                 ///   pair to identify when a result was set (for
 336                 ///   example, execution of user-provided input can be
 337                 ///   an expression, a statement or others, and
 338                 ///   result_set would only be set if the input was an
 339                 ///   expression.
 340                 ///
 341                 ///   If the return value of this function is null,
 342                 ///   this indicates that the parsing was complete.
 343                 ///   If the return value is a string, it indicates
 344                 ///   that the input is partial and that the user
 345                 ///   should provide an updated string.
 346                 /// </remarks>
 347                 public string Evaluate (string input, out object result, out bool result_set)
 348                 {
 349                         CompiledMethod compiled;
 350
 351                         result_set = false;
 352                         result = null;
 353
 354                         input = Compile (input, out compiled);
 355                         if (input != null)
 356                                 return input;
 357
 358                         if (compiled == null)
 359                                 return null;
 360
 361                         //
 362                         // The code execution does not need to keep the compiler lock
 363                         //
 364                         object retval = typeof (QuitValue);
 365
 366                         try {
 367                                 invoke_thread = System.Threading.Thread.CurrentThread;
 368                                 invoking = true;
 369                                 compiled (ref retval);
 370                         } catch (ThreadAbortException e){
 371                                 Thread.ResetAbort ();
 372                                 Console.WriteLine ("Interrupted!\n{0}", e);
 373                         } finally {
 374                                 invoking = false;
 375
 376                                 if (listener_id != null) {
 377                                         ListenerProxy.Unregister (listener_id.Value);
 378                                         listener_id = null;
 379                                 }
 380                         }
 381
 382                         //
 383                         // We use a reference to a compiler type, in this case
 384                         // Driver as a flag to indicate that this was a statement
 385                         //
 386                         if (!ReferenceEquals (retval, typeof (QuitValue))) {
 387                                 result_set = true;
 388                                 result = retval;
 389                         }
 390
 391                         return null;
 392                 }
 393
 394                 public string [] GetCompletions (string input, out string prefix)
 395                 {
 396                         prefix = "";
 397                         if (input == null || input.Length == 0)
 398                                 return null;
 399
 400                         lock (evaluator_lock){
 401                                 if (!inited)
 402                                         Init ();
 403
 404                                 bool partial_input;
 405                                 CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
 406                                 if (parser == null){
 407                                         return null;
 408                                 }
 409
 410                                 Class host = parser.InteractiveResult;
 411
 412                                 var base_class_imported = importer.ImportType (base_class);
 413                                 var baseclass_list = new List<FullNamedExpression> (1) {
 414                                         new TypeExpression (base_class_imported, host.Location)
 415                                 };
 416                                 host.SetBaseTypes (baseclass_list);
 417
 418                                 var access = AssemblyBuilderAccess.RunAndCollect;
 419                                 var a = new AssemblyDefinitionDynamic (module, "completions");
 420                                 a.Create (AppDomain.CurrentDomain, access);
 421                                 module.SetDeclaringAssembly (a);
 422
 423                                 // Need to setup MemberCache
 424                                 host.CreateContainer ();
 425                                 // Need to setup base type
 426                                 host.DefineContainer ();
 427
 428                                 var method = host.Members[0] as Method;
 429                                 BlockContext bc = new BlockContext (method, method.Block, ctx.BuiltinTypes.Void);
 430
 431                                 try {
 432                                         method.Block.Resolve (bc, method);
 433                                 } catch (CompletionResult cr) {
 434                                         prefix = cr.BaseText;
 435                                         return cr.Result;
 436                                 }
 437                         }
 438                         return null;
 439                 }
 440
 441                 /// <summary>
 442                 ///   Executes the given expression or statement.
 443                 /// </summary>
 444                 /// <remarks>
 445                 ///    Executes the provided statement, returns true
 446                 ///    on success, false on parsing errors.  Exceptions
 447                 ///    might be thrown by the called code.
 448                 /// </remarks>
 449                 public bool Run (string statement)
 450                 {
 451                         object result;
 452                         bool result_set;
 453
 454                         return Evaluate (statement, out result, out result_set) == null;
 455                 }
 456
 457                 /// <summary>
 458                 ///   Evaluates and expression or statement and returns the result.
 459                 /// </summary>
 460                 /// <remarks>
 461                 ///   Evaluates the input string as a C# expression or
 462                 ///   statement and returns the value.
 463                 ///
 464                 ///   This method will throw an exception if there is a syntax error,
 465                 ///   of if the provided input is not an expression but a statement.
 466                 /// </remarks>
 467                 public object Evaluate (string input)
 468                 {
 469                         object result;
 470                         bool result_set;
 471
 472                         string r = Evaluate (input, out result, out result_set);
 473
 474                         if (r != null)
 475                                 throw new ArgumentException ("Syntax error on input: partial input");
 476
 477                         if (result_set == false)
 478                                 throw new ArgumentException ("The expression failed to resolve");
 479
 480                         return result;
 481                 }
 482
 483                 /// <summary>
 484                 /// Experimental!
 485                 /// </summary>
 486                 public ValueModificationHandler ModificationListener { get; set; }
 487
 488                 enum InputKind {
 489                         EOF,
 490                         StatementOrExpression,
 491                         CompilationUnit,
 492                         Error
 493                 }
 494
 495                 //
 496                 // Deambiguates the input string to determine if we
 497                 // want to process a statement or if we want to
 498                 // process a compilation unit.
 499                 //
 500                 // This is done using a top-down predictive parser,
 501                 // since the yacc/jay parser can not deambiguage this
 502                 // without more than one lookahead token.   There are very
 503                 // few ambiguities.
 504                 //
 505                 InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 506                 {
 507                         Tokenizer tokenizer = new Tokenizer (seekable, source_file, new ParserSession (), ctx.Report);
 508
 509                         // Prefer contextual block keywords over identifiers
 510                         tokenizer.parsing_block++;
 511
 512                         int t = tokenizer.token ();
 513                         switch (t){
 514                         case Token.EOF:
 515                                 return InputKind.EOF;
 516
 517                         // These are toplevels
 518                         case Token.EXTERN:
 519                         case Token.OPEN_BRACKET:
 520                         case Token.OPEN_BRACKET_EXPR:
 521                         case Token.ABSTRACT:
 522                         case Token.CLASS:
 523                         case Token.ENUM:
 524                         case Token.INTERFACE:
 525                         case Token.INTERNAL:
 526                         case Token.NAMESPACE:
 527                         case Token.PRIVATE:
 528                         case Token.PROTECTED:
 529                         case Token.PUBLIC:
 530                         case Token.SEALED:
 531                         case Token.STATIC:
 532                         case Token.STRUCT:
 533                                 return InputKind.CompilationUnit;
 534
 535                         // Definitely expression
 536                         case Token.FIXED:
 537                         case Token.BOOL:
 538                         case Token.BYTE:
 539                         case Token.CHAR:
 540                         case Token.DECIMAL:
 541                         case Token.DOUBLE:
 542                         case Token.FLOAT:
 543                         case Token.INT:
 544                         case Token.LONG:
 545                         case Token.NEW:
 546                         case Token.OBJECT:
 547                         case Token.SBYTE:
 548                         case Token.SHORT:
 549                         case Token.STRING:
 550                         case Token.UINT:
 551                         case Token.ULONG:
 552                                 return InputKind.StatementOrExpression;
 553
 554                         // These need deambiguation help
 555                         case Token.USING:
 556                                 t = tokenizer.token ();
 557                                 if (t == Token.EOF)
 558                                         return InputKind.EOF;
 559
 560                                 if (t == Token.IDENTIFIER || t == Token.STATIC)
 561                                         return InputKind.CompilationUnit;
 562                                 return InputKind.StatementOrExpression;
 563
 564
 565                         // Distinguish between:
 566                         //    delegate opt_anonymous_method_signature block
 567                         //    delegate type
 568                         case Token.DELEGATE:
 569                                 t = tokenizer.token ();
 570                                 if (t == Token.EOF)
 571                                         return InputKind.EOF;
 572                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 573                                         return InputKind.StatementOrExpression;
 574                                 return InputKind.CompilationUnit;
 575
 576                         // Distinguih between:
 577                         //    unsafe block
 578                         //    unsafe as modifier of a type declaration
 579                         case Token.UNSAFE:
 580                                 t = tokenizer.token ();
 581                                 if (t == Token.EOF)
 582                                         return InputKind.EOF;
 583                                 if (t == Token.OPEN_PARENS)
 584                                         return InputKind.StatementOrExpression;
 585                                 return InputKind.CompilationUnit;
 586
 587                         // These are errors: we list explicitly what we had
 588                         // from the grammar, ERROR and then everything else
 589
 590                         case Token.READONLY:
 591                         case Token.OVERRIDE:
 592                         case Token.ERROR:
 593                                 return InputKind.Error;
 594
 595                         // This catches everything else allowed by
 596                         // expressions.  We could add one-by-one use cases
 597                         // if needed.
 598                         default:
 599                                 return InputKind.StatementOrExpression;
 600                         }
 601                 }
 602
 603                 //
 604                 // Parses the string @input and returns a CSharpParser if succeeful.
 605                 //
 606                 // if @silent is set to true then no errors are
 607                 // reported to the user.  This is used to do various calls to the
 608                 // parser and check if the expression is parsable.
 609                 //
 610                 // @partial_input: if @silent is true, then it returns whether the
 611                 // parsed expression was partial, and more data is needed
 612                 //
 613                 CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 614                 {
 615                         partial_input = false;
 616                         Reset ();
 617
 618                         var enc = ctx.Settings.Encoding;
 619                         var s = new MemoryStream (enc.GetBytes (input));
 620                         SeekableStreamReader seekable = new SeekableStreamReader (s, enc);
 621
 622                         InputKind kind = ToplevelOrStatement (seekable);
 623                         if (kind == InputKind.Error){
 624                                 if (mode == ParseMode.ReportErrors)
 625                                         ctx.Report.Error (-25, "Detection Parsing Error");
 626                                 partial_input = false;
 627                                 return null;
 628                         }
 629
 630                         if (kind == InputKind.EOF){
 631                                 if (mode == ParseMode.ReportErrors)
 632                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 633                                 partial_input = true;
 634                                 return null;
 635
 636                         }
 637                         seekable.Position = 0;
 638
 639                         source_file.DeclarationFound = false;
 640                         CSharpParser parser = new CSharpParser (seekable, source_file, new ParserSession ());
 641
 642                         if (kind == InputKind.StatementOrExpression){
 643                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 644                                 parser.Lexer.parsing_block++;
 645                                 ctx.Settings.StatementMode = true;
 646                         } else {
 647                                 parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 648                                 ctx.Settings.StatementMode = false;
 649                         }
 650
 651                         if (mode == ParseMode.GetCompletions)
 652                                 parser.Lexer.CompleteOnEOF = true;
 653
 654                         ReportPrinter old_printer = null;
 655                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions))
 656                                 old_printer = ctx.Report.SetPrinter (new StreamReportPrinter (TextWriter.Null));
 657
 658                         try {
 659                                 parser.parse ();
 660                         } finally {
 661                                 if (ctx.Report.Errors != 0){
 662                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 663                                                 partial_input = true;
 664
 665                                         if (parser.undo != null)
 666                                                 parser.undo.ExecuteUndo ();
 667
 668                                         parser = null;
 669                                 }
 670
 671                                 if (old_printer != null)
 672                                         ctx.Report.SetPrinter (old_printer);
 673                         }
 674                         return parser;
 675                 }
 676
 677                 CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
 678                 {
 679 #if STATIC
 680                         throw new NotSupportedException ();
 681 #else
 682                         string current_debug_name = "eval-" + count + ".dll";
 683                         ++count;
 684
 685                         AssemblyDefinitionDynamic assembly;
 686                         AssemblyBuilderAccess access;
 687
 688                         if (Environment.GetEnvironmentVariable ("SAVE") != null) {
 689                                 access = AssemblyBuilderAccess.RunAndSave;
 690                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name, current_debug_name);
 691                                 assembly.Importer = importer;
 692                         } else {
 693                                 access = AssemblyBuilderAccess.RunAndCollect;
 694                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name);
 695                         }
 696
 697                         assembly.Create (AppDomain.CurrentDomain, access);
 698
 699                         Method expression_method;
 700                         if (host != null) {
 701                                 var base_class_imported = importer.ImportType (base_class);
 702                                 var baseclass_list = new List<FullNamedExpression> (1) {
 703                                         new TypeExpression (base_class_imported, host.Location)
 704                                 };
 705
 706                                 host.SetBaseTypes (baseclass_list);
 707
 708                                 expression_method = (Method) host.Members[0];
 709
 710                                 if ((expression_method.ModFlags & Modifiers.ASYNC) != 0) {
 711                                         //
 712                                         // Host method is async. When WaitOnTask is set we wrap it with wait
 713                                         //
 714                                         // void AsyncWait (ref object $retval) {
 715                                         //      $retval = Host();
 716                                         //      ((Task)$retval).Wait();  // When WaitOnTask is set
 717                                         // }
 718                                         //
 719                                         var p = new ParametersCompiled (
 720                                                 new Parameter (new TypeExpression (module.Compiler.BuiltinTypes.Object, Location.Null), "$retval", Parameter.Modifier.REF, null, Location.Null)
 721                                         );
 722
 723                                         var method = new Method(host, new TypeExpression(module.Compiler.BuiltinTypes.Void, Location.Null),
 724                                                 Modifiers.PUBLIC | Modifiers.STATIC, new MemberName("AsyncWait"), p, null);
 725
 726                                         method.Block = new ToplevelBlock(method.Compiler, p, Location.Null);
 727                                         method.Block.AddStatement(new StatementExpression (new SimpleAssign(
 728                                                 new SimpleName(p [0].Name, Location.Null),
 729                                                 new Invocation(new SimpleName(expression_method.MemberName.Name, Location.Null), new Arguments(0)),
 730                                                 Location.Null), Location.Null));
 731
 732                                         if (WaitOnTask) {
 733                                                 var task = new Cast (expression_method.TypeExpression, new SimpleName (p [0].Name, Location.Null), Location.Null);
 734
 735                                                 method.Block.AddStatement (new StatementExpression (new Invocation (
 736                                                                 new MemberAccess (task, "Wait", Location.Null),
 737                                                         new Arguments (0)), Location.Null));
 738                                         }
 739
 740                                         host.AddMember(method);
 741
 742                                         expression_method = method;
 743                                 }
 744
 745                                 host.CreateContainer();
 746                                 host.DefineContainer();
 747                                 host.Define();
 748
 749                         } else {
 750                                 expression_method = null;
 751                         }
 752
 753                         module.CreateContainer ();
 754
 755                         // Disable module and source file re-definition checks
 756                         module.EnableRedefinition ();
 757                         source_file.EnableRedefinition ();
 758
 759                         module.Define ();
 760
 761                         if (Report.Errors != 0){
 762                                 if (undo != null)
 763                                         undo.ExecuteUndo ();
 764
 765                                 return null;
 766                         }
 767
 768                         if (host != null){
 769                                 host.PrepareEmit ();
 770                                 host.EmitContainer ();
 771                         }
 772
 773                         module.EmitContainer ();
 774
 775                         if (Report.Errors != 0){
 776                                 if (undo != null)
 777                                         undo.ExecuteUndo ();
 778                                 return null;
 779                         }
 780
 781                         module.CloseContainer ();
 782                         if (host != null)
 783                                 host.CloseContainer ();
 784
 785                         if (access == AssemblyBuilderAccess.RunAndSave)
 786                                 assembly.Save ();
 787
 788                         if (host == null)
 789                                 return null;
 790
 791                         //
 792                         // Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
 793                         // work from MethodBuilders.   Retarded, I know.
 794                         //
 795                         var tt = assembly.Builder.GetType (host.TypeBuilder.Name);
 796                         var mi = tt.GetMethod (expression_method.MemberName.Name);
 797
 798                         //
 799                         // We need to then go from FieldBuilder to FieldInfo
 800                         // or reflection gets confused (it basically gets confused, and variables override each
 801                         // other).
 802                         //
 803                         foreach (var member in host.Members) {
 804                                 var field = member as Field;
 805                                 if (field == null)
 806                                         continue;
 807
 808                                 var fi = tt.GetField (field.Name);
 809
 810                                 Tuple<FieldSpec, FieldInfo> old;
 811
 812                                 // If a previous value was set, nullify it, so that we do
 813                                 // not leak memory
 814                                 if (fields.TryGetValue (field.Name, out old)) {
 815                                         if (old.Item1.MemberType.IsStruct) {
 816                                                 //
 817                                                 // TODO: Clear fields for structs
 818                                                 //
 819                                         } else {
 820                                                 try {
 821                                                         old.Item2.SetValue (null, null);
 822                                                 } catch {
 823                                                 }
 824                                         }
 825                                 }
 826
 827                                 fields[field.Name] = Tuple.Create (field.Spec, fi);
 828                         }
 829
 830                         return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
 831 #endif
 832                 }
 833
 834                 /// <summary>
 835                 ///   A sentinel value used to indicate that no value was
 836                 ///   was set by the compiled function.   This is used to
 837                 ///   differentiate between a function not returning a
 838                 ///   value and null.
 839                 /// </summary>
 840                 internal static class QuitValue { }
 841
 842                 internal Tuple<FieldSpec, FieldInfo> LookupField (string name)
 843                 {
 844                         Tuple<FieldSpec, FieldInfo> fi;
 845                         fields.TryGetValue (name, out fi);
 846                         return fi;
 847                 }
 848
 849                 static string Quote (string s)
 850                 {
 851                         if (s.IndexOf ('"') != -1)
 852                                 s = s.Replace ("\"", "\\\"");
 853
 854                         return "\"" + s + "\"";
 855                 }
 856
 857                 public string GetUsing ()
 858                 {
 859                         if (source_file == null || source_file.Usings == null)
 860                                 return string.Empty;
 861
 862                         StringBuilder sb = new StringBuilder ();
 863                         // TODO:
 864                         //foreach (object x in ns.using_alias_list)
 865                         //    sb.AppendFormat ("using {0};\n", x);
 866
 867                         foreach (var ue in source_file.Usings) {
 868                                 if (ue.Alias != null || ue.ResolvedExpression == null)
 869                                         continue;
 870
 871                                 sb.AppendFormat("using {0};", ue.ToString ());
 872                                 sb.Append (Environment.NewLine);
 873                         }
 874
 875                         return sb.ToString ();
 876                 }
 877
 878                 internal List<string> GetUsingList ()
 879                 {
 880                         var res = new List<string> ();
 881
 882                         if (source_file == null || source_file.Usings == null)
 883                                 return res;
 884
 885                         foreach (var ue in source_file.Usings)
 886                         {
 887                                 if (ue.Alias != null || ue.ResolvedExpression == null)
 888                                         continue;
 889
 890                                 res.Add (ue.NamespaceExpression.Name);
 891                         }
 892
 893                         return res;
 894                 }
 895
 896                 internal string [] GetVarNames ()
 897                 {
 898                         lock (evaluator_lock){
 899                                 return new List<string> (fields.Keys).ToArray ();
 900                         }
 901                 }
 902
 903                 public string GetVars ()
 904                 {
 905                         lock (evaluator_lock){
 906                                 StringBuilder sb = new StringBuilder ();
 907
 908                                 foreach (var de in fields){
 909                                         var fi = LookupField (de.Key);
 910                                         object value;
 911                                         try {
 912                                                 value = fi.Item2.GetValue (null);
 913                                                 if (value is string)
 914                                                         value = Quote ((string)value);
 915                                         } catch {
 916                                                 value = "<error reading value>";
 917                                         }
 918
 919                                         sb.AppendFormat ("{0} {1} = {2}", fi.Item1.MemberType.GetSignatureForError (), de.Key, value);
 920                                         sb.AppendLine ();
 921                                 }
 922
 923                                 return sb.ToString ();
 924                         }
 925                 }
 926
 927                 /// <summary>
 928                 ///    Loads the given assembly and exposes the API to the user.
 929                 /// </summary>
 930                 public void LoadAssembly (string file)
 931                 {
 932                         var loader = new DynamicLoader (importer, ctx);
 933                         var assembly = loader.LoadAssemblyFile (file, false);
 934                         if (assembly == null)
 935                                 return;
 936
 937                         lock (evaluator_lock){
 938                                 importer.ImportAssembly (assembly, module.GlobalRootNamespace);
 939                         }
 940                 }
 941
 942                 /// <summary>
 943                 ///    Exposes the API of the given assembly to the Evaluator
 944                 /// </summary>
 945                 public void ReferenceAssembly (Assembly a)
 946                 {
 947                         lock (evaluator_lock){
 948                                 importer.ImportAssembly (a, module.GlobalRootNamespace);
 949                         }
 950                 }
 951         }
 952
 953
 954         /// <summary>
 955         ///   A delegate that can be used to invoke the
 956         ///   compiled expression or statement.
 957         /// </summary>
 958         /// <remarks>
 959         ///   Since the Compile methods will compile
 960         ///   statements and expressions into the same
 961         ///   delegate, you can tell if a value was returned
 962         ///   by checking whether the returned value is of type
 963         ///   NoValueSet.
 964         /// </remarks>
 965
 966         public delegate void CompiledMethod (ref object retvalue);
 967
 968         /// <summary>
 969         ///   The default base class for every interaction line
 970         /// </summary>
 971         /// <remarks>
 972         ///   The expressions and statements behave as if they were
 973         ///   a static method of this class.   The InteractiveBase class
 974         ///   contains a number of useful methods, but can be overwritten
 975         ///   by setting the InteractiveBaseType property in the Evaluator
 976         /// </remarks>
 977         public class InteractiveBase {
 978                 /// <summary>
 979                 ///   Determines where the standard output of methods in this class will go.
 980                 /// </summary>
 981                 public static TextWriter Output = Console.Out;
 982
 983                 /// <summary>
 984                 ///   Determines where the standard error of methods in this class will go.
 985                 /// </summary>
 986                 public static TextWriter Error = Console.Error;
 987
 988                 /// <summary>
 989                 ///   The primary prompt used for interactive use.
 990                 /// </summary>
 991                 public static string Prompt             = "csharp> ";
 992
 993                 /// <summary>
 994                 ///   The secondary prompt used for interactive use (used when
 995                 ///   an expression is incomplete).
 996                 /// </summary>
 997                 public static string ContinuationPrompt = "      > ";
 998
 999                 /// <summary>
1000                 ///   Used to signal that the user has invoked the  `quit' statement.
1001                 /// </summary>
1002                 public static bool QuitRequested;
1003
1004                 public static Evaluator Evaluator;
1005
1006                 /// <summary>
1007                 ///   Shows all the variables defined so far.
1008                 /// </summary>
1009                 static public void ShowVars ()
1010                 {
1011                         Output.Write (Evaluator.GetVars ());
1012                         Output.Flush ();
1013                 }
1014
1015                 /// <summary>
1016                 ///   Displays the using statements in effect at this point.
1017                 /// </summary>
1018                 static public void ShowUsing ()
1019                 {
1020                         Output.Write (Evaluator.GetUsing ());
1021                         Output.Flush ();
1022                 }
1023
1024                 /// <summary>
1025                 ///   Times the execution of the given delegate
1026                 /// </summary>
1027                 static public TimeSpan Time (Action a)
1028                 {
1029                         DateTime start = DateTime.Now;
1030                         a ();
1031                         return DateTime.Now - start;
1032                 }
1033
1034                 /// <summary>
1035                 ///   Loads the assemblies from a package
1036                 /// </summary>
1037                 /// <remarks>
1038                 ///   Loads the assemblies from a package.   This is equivalent
1039                 ///   to passing the -pkg: command line flag to the C# compiler
1040                 ///   on the command line.
1041                 /// </remarks>
1042                 static public void LoadPackage (string pkg)
1043                 {
1044                         if (pkg == null){
1045                                 Error.WriteLine ("Invalid package specified");
1046                                 return;
1047                         }
1048
1049                         string pkgout = Driver.GetPackageFlags (pkg, null);
1050
1051                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
1052                                 Split (new Char [] { ' ', '\t'});
1053
1054                         foreach (string s in xargs){
1055                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
1056                                         string lib = s.Substring (s.IndexOf (':')+1);
1057
1058                                         Evaluator.LoadAssembly (lib);
1059                                         continue;
1060                                 }
1061                         }
1062                 }
1063
1064                 /// <summary>
1065                 ///   Loads the assembly
1066                 /// </summary>
1067                 /// <remarks>
1068                 ///   Loads the specified assembly and makes its types
1069                 ///   available to the evaluator.  This is equivalent
1070                 ///   to passing the -pkg: command line flag to the C#
1071                 ///   compiler on the command line.
1072                 /// </remarks>
1073                 static public void LoadAssembly (string assembly)
1074                 {
1075                         Evaluator.LoadAssembly (assembly);
1076                 }
1077
1078                 static public void print (object obj)
1079                 {
1080                         Output.WriteLine (obj);
1081                 }
1082
1083                 static public void print (string fmt, params object [] args)
1084                 {
1085                         Output.WriteLine (fmt, args);
1086                 }
1087
1088                 /// <summary>
1089                 ///   Returns a list of available static methods.
1090                 /// </summary>
1091                 static public string help {
1092                         get {
1093                                 return "Static methods:\n" +
1094                                         "  Describe (object);       - Describes the object's type\n" +
1095                                         "  LoadPackage (package);   - Loads the given Package (like -pkg:FILE)\n" +
1096                                         "  LoadAssembly (assembly); - Loads the given assembly (like -r:ASSEMBLY)\n" +
1097                                         "  ShowVars ();             - Shows defined local variables.\n" +
1098                                         "  ShowUsing ();            - Show active using declarations.\n" +
1099                                         "  Prompt                   - The prompt used by the C# shell\n" +
1100                                         "  ContinuationPrompt       - The prompt for partial input\n" +
1101                                         "  Time (() => { });        - Times the specified code\n" +
1102                                         "  print (obj);             - Shorthand for Console.WriteLine\n" +
1103                                         "  quit;                    - You'll never believe it - this quits the repl!\n" +
1104                                         "  help;                    - This help text\n";
1105                         }
1106                 }
1107
1108                 /// <summary>
1109                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1110                 /// </summary>
1111                 static public object quit {
1112                         get {
1113                                 QuitRequested = true;
1114
1115                                 // To avoid print null at the exit
1116                                 return typeof (Evaluator.QuitValue);
1117                         }
1118                 }
1119
1120                 /// <summary>
1121                 ///   Same as quit - useful in script scenerios
1122                 /// </summary>
1123                 static public void Quit () {
1124                         QuitRequested = true;
1125                 }
1126
1127 #if !NET_2_1
1128                 /// <summary>
1129                 ///   Describes an object or a type.
1130                 /// </summary>
1131                 /// <remarks>
1132                 ///   This method will show a textual representation
1133                 ///   of the object's type.  If the object is a
1134                 ///   System.Type it renders the type directly,
1135                 ///   otherwise it renders the type returned by
1136                 ///   invoking GetType on the object.
1137                 /// </remarks>
1138                 static public string Describe (object x)
1139                 {
1140                         if (x == null)
1141                                 return "<null>";
1142
1143                         var type = x as Type ?? x.GetType ();
1144
1145                         StringWriter sw = new StringWriter ();
1146                         new Outline (type, sw, true, false, false).OutlineType ();
1147                         return sw.ToString ();
1148                 }
1149 #endif
1150         }
1151
1152         class InteractiveMethod : Method
1153         {
1154                 public InteractiveMethod(TypeDefinition parent, FullNamedExpression returnType, Modifiers mod, ParametersCompiled parameters)
1155                         : base(parent, returnType, mod, new MemberName("Host"), parameters, null)
1156                 {
1157                 }
1158
1159                 public void ChangeToAsync ()
1160                 {
1161                         ModFlags |= Modifiers.ASYNC;
1162                         ModFlags &= ~Modifiers.UNSAFE;
1163                         type_expr = new TypeExpression(Module.PredefinedTypes.Task.TypeSpec, Location);
1164                         parameters = ParametersCompiled.EmptyReadOnlyParameters;
1165                 }
1166
1167                 public override string GetSignatureForError()
1168                 {
1169                         return "InteractiveHost";
1170                 }
1171         }
1172
1173         class HoistedEvaluatorVariable : HoistedVariable
1174         {
1175                 public HoistedEvaluatorVariable (Field field)
1176                         : base (null, field)
1177                 {
1178                 }
1179
1180                 protected override FieldExpr GetFieldExpression (EmitContext ec)
1181                 {
1182                         return new FieldExpr (field, field.Location);
1183                 }
1184         }
1185
1186         /// <summary>
1187         ///    A class used to assign values if the source expression is not void
1188         ///
1189         ///    Used by the interactive shell to allow it to call this code to set
1190         ///    the return value for an invocation.
1191         /// </summary>
1192         class OptionalAssign : SimpleAssign {
1193                 public OptionalAssign (Expression s, Location loc)
1194                         : base (null, s, loc)
1195                 {
1196                 }
1197
1198                 public override Location StartLocation {
1199                         get {
1200                                 return Location.Null;
1201                         }
1202                 }
1203
1204                 protected override Expression DoResolve (ResolveContext ec)
1205                 {
1206                         Expression clone = source.Clone (new CloneContext ());
1207
1208                         clone = clone.Resolve (ec);
1209                         if (clone == null)
1210                                 return null;
1211
1212                         //
1213                         // A useful feature for the REPL: if we can resolve the expression
1214                         // as a type, Describe the type;
1215                         //
1216                         if (ec.Module.Evaluator.DescribeTypeExpressions && !(ec.CurrentAnonymousMethod is AsyncInitializer)) {
1217                                 var old_printer = ec.Report.SetPrinter (new SessionReportPrinter ());
1218                                 Expression tclone;
1219                                 try {
1220                                         // Note: clone context cannot be shared otherwise block mapping would leak
1221                                         tclone = source.Clone (new CloneContext ());
1222                                         tclone = tclone.Resolve (ec, ResolveFlags.Type);
1223                                         if (ec.Report.Errors > 0)
1224                                                 tclone = null;
1225                                 } finally {
1226                                         ec.Report.SetPrinter (old_printer);
1227                                 }
1228
1229                                 if (tclone is TypeExpr) {
1230                                         Arguments args = new Arguments (1);
1231                                         args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
1232                                         return new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
1233                                 }
1234                         }
1235
1236                         // This means its really a statement.
1237                         if (clone.Type.Kind == MemberKind.Void || clone is DynamicInvocation || clone is Assign) {
1238                                 return clone;
1239                         }
1240
1241                         source = clone;
1242
1243                         var host = (Method) ec.MemberContext.CurrentMemberDefinition;
1244
1245                         if (host.ParameterInfo.IsEmpty) {
1246                                 eclass = ExprClass.Value;
1247                                 type = InternalType.FakeInternalType;
1248                                 return this;
1249                         }
1250
1251                         target = new SimpleName (host.ParameterInfo[0].Name, Location);
1252
1253                         return base.DoResolve (ec);
1254                 }
1255
1256                 public override void EmitStatement(EmitContext ec)
1257                 {
1258                         if (target == null) {
1259                                 source.Emit (ec);
1260                                 return;
1261                         }
1262
1263                         base.EmitStatement(ec);
1264                 }
1265         }
1266
1267         public class Undo
1268         {
1269                 List<Action> undo_actions;
1270
1271                 public void AddTypeContainer (TypeContainer current_container, TypeDefinition tc)
1272                 {
1273                         if (current_container == tc){
1274                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1275                                 return;
1276                         }
1277
1278                         if (undo_actions == null)
1279                                 undo_actions = new List<Action> ();
1280
1281                         if (current_container.Containers != null)
1282                         {
1283                                 var existing = current_container.Containers.FirstOrDefault (l => l.MemberName.Basename == tc.MemberName.Basename);
1284                                 if (existing != null) {
1285                                         current_container.RemoveContainer (existing);
1286                                         undo_actions.Add (() => current_container.AddTypeContainer (existing));
1287                                 }
1288                         }
1289
1290                         undo_actions.Add (() => current_container.RemoveContainer (tc));
1291                 }
1292
1293                 public void ExecuteUndo ()
1294                 {
1295                         if (undo_actions == null)
1296                                 return;
1297
1298                         foreach (var p in undo_actions){
1299                                 p ();
1300                         }
1301
1302                         undo_actions = null;
1303                 }
1304         }
1305
1306         static class ListenerProxy
1307         {
1308                 static readonly Dictionary<int, ValueModificationHandler> listeners = new Dictionary<int, ValueModificationHandler> ();
1309
1310                 static int counter;
1311
1312                 public static int Register (ValueModificationHandler listener)
1313                 {
1314                         lock (listeners) {
1315                                 var id = counter++;
1316                                 listeners.Add (id, listener);
1317                                 return id;
1318                         }
1319                 }
1320
1321                 public static void Unregister (int listenerId)
1322                 {
1323                         lock (listeners) {
1324                                 listeners.Remove (listenerId);
1325                         }
1326                 }
1327
1328                 public static void ValueChanged (object value, int row, int col, string name, int listenerId)
1329                 {
1330                         ValueModificationHandler action;
1331                         lock (listeners) {
1332                                 if (!listeners.TryGetValue (listenerId, out action))
1333                                         return;
1334                         }
1335
1336                         action (name, row, col, value);
1337                 }
1338         }
1339 }