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         ///   Evaluator: provides an API to evaluate C# statements and
  29         ///   expressions dynamically.
  30         /// </summary>
  31         /// <remarks>
  32         ///   This class exposes static methods to evaluate expressions in the
  33         ///   current program.
  34         ///
  35         ///   To initialize the evaluator with a number of compiler
  36         ///   options call the Init(string[]args) method with a set of
  37         ///   command line options that the compiler recognizes.
  38         ///
  39         ///   To interrupt execution of a statement, you can invoke the
  40         ///   Evaluator.Interrupt method.
  41         /// </remarks>
  42         public class Evaluator {
  43
  44                 enum ParseMode {
  45                         // Parse silently, do not output any error messages
  46                         Silent,
  47
  48                         // Report errors during parse
  49                         ReportErrors,
  50
  51                         // Auto-complete, means that the tokenizer will start producing
  52                         // GETCOMPLETIONS tokens when it reaches a certain point.
  53                         GetCompletions
  54                 }
  55
  56                 static object evaluator_lock = new object ();
  57                 static volatile bool invoking;
  58
  59 #if !STATIC
  60                 static int count;
  61 #endif
  62                 static Thread invoke_thread;
  63
  64                 readonly Dictionary<string, Tuple<FieldSpec, FieldInfo>> fields;
  65
  66                 Type base_class;
  67                 bool inited;
  68                 int startup_files;
  69
  70                 readonly CompilerContext ctx;
  71                 readonly ModuleContainer module;
  72                 readonly ReflectionImporter importer;
  73                 readonly CompilationSourceFile source_file;
  74
  75                 int? listener_id;
  76
  77                 public Evaluator (CompilerContext ctx)
  78                 {
  79                         this.ctx = ctx;
  80
  81                         module = new ModuleContainer (ctx);
  82                         module.Evaluator = this;
  83
  84                         source_file = new CompilationSourceFile (module, null);
  85                         module.AddTypeContainer (source_file);
  86
  87                         startup_files = ctx.SourceFiles.Count;
  88
  89                         // FIXME: Importer needs this assembly for internalsvisibleto
  90                         module.SetDeclaringAssembly (new AssemblyDefinitionDynamic (module, "evaluator"));
  91                         importer = new ReflectionImporter (module, ctx.BuiltinTypes);
  92
  93                         InteractiveBaseClass = typeof (InteractiveBase);
  94                         fields = new Dictionary<string, Tuple<FieldSpec, FieldInfo>> ();
  95                 }
  96
  97                 void Init ()
  98                 {
  99                         var loader = new DynamicLoader (importer, ctx);
 100
 101                         CompilerCallableEntryPoint.Reset ();
 102                         RootContext.ToplevelTypes = module;
 103
 104                         //var startup_files = new List<string> ();
 105                         //foreach (CompilationUnit file in Location.SourceFiles)
 106                         //    startup_files.Add (file.Path);
 107
 108                         loader.LoadReferences (module);
 109                         ctx.BuiltinTypes.CheckDefinitions (module);
 110                         module.InitializePredefinedTypes ();
 111
 112                         inited = true;
 113                 }
 114
 115                 void ParseStartupFiles ()
 116                 {
 117                         Driver d = new Driver (ctx);
 118
 119                         Location.Initialize (ctx.SourceFiles);
 120
 121                         var parser_session = new ParserSession ();
 122                         for (int i = 0; i < startup_files; ++i) {
 123                                 var sf = ctx.SourceFiles [i];
 124                                 d.Parse (sf, module, parser_session, ctx.Report);
 125                         }
 126                 }
 127
 128                 void Reset ()
 129                 {
 130                         CompilerCallableEntryPoint.PartialReset ();
 131
 132                         Location.Reset ();
 133                         Location.Initialize (ctx.SourceFiles);
 134                 }
 135
 136                 /// <summary>
 137                 /// When set evaluator will automatically wait on Task of async methods. When not
 138                 /// set it's called responsibility to handle Task execution
 139                 /// </summary>
 140                 public bool WaitOnTask { get; set; }
 141
 142                 /// <summary>
 143                 ///   If true, turns type expressions into valid expressions
 144                 ///   and calls the describe method on it
 145                 /// </summary>
 146                 public bool DescribeTypeExpressions;
 147
 148                 /// <summary>
 149                 ///   Whether the evaluator will use terse syntax, and the semicolons at the end are optional
 150                 /// </summary>
 151                 public bool Terse = true;
 152
 153                 /// <summary>
 154                 ///   The base class for the classes that host the user generated code
 155                 /// </summary>
 156                 /// <remarks>
 157                 ///
 158                 ///   This is the base class that will host the code
 159                 ///   executed by the Evaluator.  By default
 160                 ///   this is the Mono.CSharp.InteractiveBase class
 161                 ///   which is useful for interactive use.
 162                 ///
 163                 ///   By changing this property you can control the
 164                 ///   base class and the static members that are
 165                 ///   available to your evaluated code.
 166                 /// </remarks>
 167                 public Type InteractiveBaseClass {
 168                         get {
 169                                 return base_class;
 170                         }
 171                         set {
 172                                 base_class = value;
 173
 174                                 if (value != null && typeof (InteractiveBase).IsAssignableFrom (value))
 175                                         InteractiveBase.Evaluator = this;
 176                         }
 177                 }
 178
 179                 /// <summary>
 180                 ///   Interrupts the evaluation of an expression executing in Evaluate.
 181                 /// </summary>
 182                 /// <remarks>
 183                 ///   Use this method to interrupt long-running invocations.
 184                 /// </remarks>
 185                 public void Interrupt ()
 186                 {
 187                         if (!inited || !invoking)
 188                                 return;
 189
 190                         if (invoke_thread != null)
 191                                 invoke_thread.Abort ();
 192                 }
 193
 194                 /// <summary>
 195                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 196                 /// </summary>
 197                 /// <remarks>
 198                 ///
 199                 ///   Compiles the input string as a C# expression or
 200                 ///   statement, unlike the Evaluate method, the
 201                 ///   resulting delegate can be invoked multiple times
 202                 ///   without incurring in the compilation overhead.
 203                 ///
 204                 ///   If the return value of this function is null,
 205                 ///   this indicates that the parsing was complete.
 206                 ///   If the return value is a string it indicates
 207                 ///   that the input string was partial and that the
 208                 ///   invoking code should provide more code before
 209                 ///   the code can be successfully compiled.
 210                 ///
 211                 ///   If you know that you will always get full expressions or
 212                 ///   statements and do not care about partial input, you can use
 213                 ///   the other Compile overload.
 214                 ///
 215                 ///   On success, in addition to returning null, the
 216                 ///   compiled parameter will be set to the delegate
 217                 ///   that can be invoked to execute the code.
 218                 ///
 219                 /// </remarks>
 220                 public string Compile (string input, out CompiledMethod compiled)
 221                 {
 222                         if (input == null || input.Length == 0){
 223                                 compiled = null;
 224                                 return null;
 225                         }
 226
 227                         lock (evaluator_lock){
 228                                 if (!inited) {
 229                                         Init ();
 230                                         ParseStartupFiles ();
 231                                 } else {
 232                                         ctx.Report.Printer.Reset ();
 233                                 }
 234
 235                                 bool partial_input;
 236                                 CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
 237
 238                                 // Terse mode, try to provide the trailing semicolon automatically.
 239                                 if (parser == null && Terse && partial_input){
 240                                         bool ignore;
 241
 242                                         // check if the source would compile with a block, if so, we should not
 243                                         // add the semicolon.
 244                                         var needs_block = ParseString (ParseMode.Silent, input + "{}", out ignore) != null;
 245                                         if (!needs_block)
 246                                                 parser = ParseString (ParseMode.Silent, input + ";", out ignore);
 247                                 }
 248                                 if (parser == null){
 249                                         compiled = null;
 250                                         if (partial_input)
 251                                                 return input;
 252
 253                                         ParseString (ParseMode.ReportErrors, input, out partial_input);
 254                                         return null;
 255                                 }
 256
 257                                 Class parser_result = parser.InteractiveResult;
 258                                 compiled = CompileBlock (parser_result, parser.undo, ctx.Report);
 259                                 return null;
 260                         }
 261                 }
 262
 263                 /// <summary>
 264                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 265                 /// </summary>
 266                 /// <remarks>
 267                 ///
 268                 ///   Compiles the input string as a C# expression or
 269                 ///   statement, unlike the Evaluate method, the
 270                 ///   resulting delegate can be invoked multiple times
 271                 ///   without incurring in the compilation overhead.
 272                 ///
 273                 ///   This method can only deal with fully formed input
 274                 ///   strings and does not provide a completion mechanism.
 275                 ///   If you must deal with partial input (for example for
 276                 ///   interactive use) use the other overload.
 277                 ///
 278                 ///   On success, a delegate is returned that can be used
 279                 ///   to invoke the method.
 280                 ///
 281                 /// </remarks>
 282                 public CompiledMethod Compile (string input)
 283                 {
 284                         CompiledMethod compiled;
 285
 286                         // Ignore partial inputs
 287                         if (Compile (input, out compiled) != null){
 288                                 // Error, the input was partial.
 289                                 return null;
 290                         }
 291
 292                         // Either null (on error) or the compiled method.
 293                         return compiled;
 294                 }
 295
 296                 static MethodInfo listener_proxy_value;
 297                 internal void EmitValueChangedCallback (EmitContext ec, string name, TypeSpec type, Location loc)
 298                 {
 299                         if (listener_id == null)
 300                                 listener_id = ListenerProxy.Register (ModificationListener);
 301
 302                         if (listener_proxy_value == null)
 303                                 listener_proxy_value = typeof (ListenerProxy).GetMethod ("ValueChanged");
 304
 305 #if STATIC
 306                         throw new NotSupportedException ();
 307 #else
 308                         // object value, int row, int col, string name, int listenerId
 309                         if (type.IsStructOrEnum)
 310                                 ec.Emit (OpCodes.Box, type);
 311
 312                         ec.EmitInt (loc.Row);
 313                         ec.EmitInt (loc.Column);
 314                         ec.Emit (OpCodes.Ldstr, name);
 315                         ec.EmitInt (listener_id.Value);
 316                         ec.Emit (OpCodes.Call, listener_proxy_value);
 317 #endif
 318                 }
 319
 320                 /// <summary>
 321                 ///   Evaluates and expression or statement and returns any result values.
 322                 /// </summary>
 323                 /// <remarks>
 324                 ///   Evaluates the input string as a C# expression or
 325                 ///   statement.  If the input string is an expression
 326                 ///   the result will be stored in the result variable
 327                 ///   and the result_set variable will be set to true.
 328                 ///
 329                 ///   It is necessary to use the result/result_set
 330                 ///   pair to identify when a result was set (for
 331                 ///   example, execution of user-provided input can be
 332                 ///   an expression, a statement or others, and
 333                 ///   result_set would only be set if the input was an
 334                 ///   expression.
 335                 ///
 336                 ///   If the return value of this function is null,
 337                 ///   this indicates that the parsing was complete.
 338                 ///   If the return value is a string, it indicates
 339                 ///   that the input is partial and that the user
 340                 ///   should provide an updated string.
 341                 /// </remarks>
 342                 public string Evaluate (string input, out object result, out bool result_set)
 343                 {
 344                         CompiledMethod compiled;
 345
 346                         result_set = false;
 347                         result = null;
 348
 349                         input = Compile (input, out compiled);
 350                         if (input != null)
 351                                 return input;
 352
 353                         if (compiled == null)
 354                                 return null;
 355
 356                         //
 357                         // The code execution does not need to keep the compiler lock
 358                         //
 359                         object retval = typeof (QuitValue);
 360
 361                         try {
 362                                 invoke_thread = System.Threading.Thread.CurrentThread;
 363                                 invoking = true;
 364                                 compiled (ref retval);
 365                         } catch (ThreadAbortException e){
 366                                 Thread.ResetAbort ();
 367                                 Console.WriteLine ("Interrupted!\n{0}", e);
 368                         } finally {
 369                                 invoking = false;
 370
 371                                 if (listener_id != null) {
 372                                         ListenerProxy.Unregister (listener_id.Value);
 373                                         listener_id = null;
 374                                 }
 375                         }
 376
 377                         //
 378                         // We use a reference to a compiler type, in this case
 379                         // Driver as a flag to indicate that this was a statement
 380                         //
 381                         if (!ReferenceEquals (retval, typeof (QuitValue))) {
 382                                 result_set = true;
 383                                 result = retval;
 384                         }
 385
 386                         return null;
 387                 }
 388
 389                 public string [] GetCompletions (string input, out string prefix)
 390                 {
 391                         prefix = "";
 392                         if (input == null || input.Length == 0)
 393                                 return null;
 394
 395                         lock (evaluator_lock){
 396                                 if (!inited)
 397                                         Init ();
 398
 399                                 bool partial_input;
 400                                 CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
 401                                 if (parser == null){
 402                                         return null;
 403                                 }
 404
 405                                 Class host = parser.InteractiveResult;
 406
 407                                 var base_class_imported = importer.ImportType (base_class);
 408                                 var baseclass_list = new List<FullNamedExpression> (1) {
 409                                         new TypeExpression (base_class_imported, host.Location)
 410                                 };
 411                                 host.SetBaseTypes (baseclass_list);
 412
 413 #if NET_4_0
 414                                 var access = AssemblyBuilderAccess.RunAndCollect;
 415 #else
 416                                 var access = AssemblyBuilderAccess.Run;
 417 #endif
 418                                 var a = new AssemblyDefinitionDynamic (module, "completions");
 419                                 a.Create (AppDomain.CurrentDomain, access);
 420                                 module.SetDeclaringAssembly (a);
 421
 422                                 // Need to setup MemberCache
 423                                 host.CreateContainer ();
 424                                 // Need to setup base type
 425                                 host.DefineContainer ();
 426
 427                                 var method = host.Members[0] as Method;
 428                                 BlockContext bc = new BlockContext (method, method.Block, ctx.BuiltinTypes.Void);
 429
 430                                 try {
 431                                         method.Block.Resolve (bc, method);
 432                                 } catch (CompletionResult cr) {
 433                                         prefix = cr.BaseText;
 434                                         return cr.Result;
 435                                 }
 436                         }
 437                         return null;
 438                 }
 439
 440                 /// <summary>
 441                 ///   Executes the given expression or statement.
 442                 /// </summary>
 443                 /// <remarks>
 444                 ///    Executes the provided statement, returns true
 445                 ///    on success, false on parsing errors.  Exceptions
 446                 ///    might be thrown by the called code.
 447                 /// </remarks>
 448                 public bool Run (string statement)
 449                 {
 450                         object result;
 451                         bool result_set;
 452
 453                         return Evaluate (statement, out result, out result_set) == null;
 454                 }
 455
 456                 /// <summary>
 457                 ///   Evaluates and expression or statement and returns the result.
 458                 /// </summary>
 459                 /// <remarks>
 460                 ///   Evaluates the input string as a C# expression or
 461                 ///   statement and returns the value.
 462                 ///
 463                 ///   This method will throw an exception if there is a syntax error,
 464                 ///   of if the provided input is not an expression but a statement.
 465                 /// </remarks>
 466                 public object Evaluate (string input)
 467                 {
 468                         object result;
 469                         bool result_set;
 470
 471                         string r = Evaluate (input, out result, out result_set);
 472
 473                         if (r != null)
 474                                 throw new ArgumentException ("Syntax error on input: partial input");
 475
 476                         if (result_set == false)
 477                                 throw new ArgumentException ("The expression failed to resolve");
 478
 479                         return result;
 480                 }
 481
 482                 // Experimental
 483                 public Action<string, int, int, object> ModificationListener { get; set; }
 484
 485                 enum InputKind {
 486                         EOF,
 487                         StatementOrExpression,
 488                         CompilationUnit,
 489                         Error
 490                 }
 491
 492                 //
 493                 // Deambiguates the input string to determine if we
 494                 // want to process a statement or if we want to
 495                 // process a compilation unit.
 496                 //
 497                 // This is done using a top-down predictive parser,
 498                 // since the yacc/jay parser can not deambiguage this
 499                 // without more than one lookahead token.   There are very
 500                 // few ambiguities.
 501                 //
 502                 InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 503                 {
 504                         Tokenizer tokenizer = new Tokenizer (seekable, source_file, new ParserSession (), ctx.Report);
 505
 506                         // Prefer contextual block keywords over identifiers
 507                         tokenizer.parsing_block++;
 508
 509                         int t = tokenizer.token ();
 510                         switch (t){
 511                         case Token.EOF:
 512                                 return InputKind.EOF;
 513
 514                         // These are toplevels
 515                         case Token.EXTERN:
 516                         case Token.OPEN_BRACKET:
 517                         case Token.ABSTRACT:
 518                         case Token.CLASS:
 519                         case Token.ENUM:
 520                         case Token.INTERFACE:
 521                         case Token.INTERNAL:
 522                         case Token.NAMESPACE:
 523                         case Token.PRIVATE:
 524                         case Token.PROTECTED:
 525                         case Token.PUBLIC:
 526                         case Token.SEALED:
 527                         case Token.STATIC:
 528                         case Token.STRUCT:
 529                                 return InputKind.CompilationUnit;
 530
 531                         // Definitely expression
 532                         case Token.FIXED:
 533                         case Token.BOOL:
 534                         case Token.BYTE:
 535                         case Token.CHAR:
 536                         case Token.DECIMAL:
 537                         case Token.DOUBLE:
 538                         case Token.FLOAT:
 539                         case Token.INT:
 540                         case Token.LONG:
 541                         case Token.NEW:
 542                         case Token.OBJECT:
 543                         case Token.SBYTE:
 544                         case Token.SHORT:
 545                         case Token.STRING:
 546                         case Token.UINT:
 547                         case Token.ULONG:
 548                                 return InputKind.StatementOrExpression;
 549
 550                         // These need deambiguation help
 551                         case Token.USING:
 552                                 t = tokenizer.token ();
 553                                 if (t == Token.EOF)
 554                                         return InputKind.EOF;
 555
 556                                 if (t == Token.IDENTIFIER)
 557                                         return InputKind.CompilationUnit;
 558                                 return InputKind.StatementOrExpression;
 559
 560
 561                         // Distinguish between:
 562                         //    delegate opt_anonymous_method_signature block
 563                         //    delegate type
 564                         case Token.DELEGATE:
 565                                 t = tokenizer.token ();
 566                                 if (t == Token.EOF)
 567                                         return InputKind.EOF;
 568                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 569                                         return InputKind.StatementOrExpression;
 570                                 return InputKind.CompilationUnit;
 571
 572                         // Distinguih between:
 573                         //    unsafe block
 574                         //    unsafe as modifier of a type declaration
 575                         case Token.UNSAFE:
 576                                 t = tokenizer.token ();
 577                                 if (t == Token.EOF)
 578                                         return InputKind.EOF;
 579                                 if (t == Token.OPEN_PARENS)
 580                                         return InputKind.StatementOrExpression;
 581                                 return InputKind.CompilationUnit;
 582
 583                         // These are errors: we list explicitly what we had
 584                         // from the grammar, ERROR and then everything else
 585
 586                         case Token.READONLY:
 587                         case Token.OVERRIDE:
 588                         case Token.ERROR:
 589                                 return InputKind.Error;
 590
 591                         // This catches everything else allowed by
 592                         // expressions.  We could add one-by-one use cases
 593                         // if needed.
 594                         default:
 595                                 return InputKind.StatementOrExpression;
 596                         }
 597                 }
 598
 599                 //
 600                 // Parses the string @input and returns a CSharpParser if succeeful.
 601                 //
 602                 // if @silent is set to true then no errors are
 603                 // reported to the user.  This is used to do various calls to the
 604                 // parser and check if the expression is parsable.
 605                 //
 606                 // @partial_input: if @silent is true, then it returns whether the
 607                 // parsed expression was partial, and more data is needed
 608                 //
 609                 CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 610                 {
 611                         partial_input = false;
 612                         Reset ();
 613
 614                         var enc = ctx.Settings.Encoding;
 615                         var s = new MemoryStream (enc.GetBytes (input));
 616                         SeekableStreamReader seekable = new SeekableStreamReader (s, enc);
 617
 618                         InputKind kind = ToplevelOrStatement (seekable);
 619                         if (kind == InputKind.Error){
 620                                 if (mode == ParseMode.ReportErrors)
 621                                         ctx.Report.Error (-25, "Detection Parsing Error");
 622                                 partial_input = false;
 623                                 return null;
 624                         }
 625
 626                         if (kind == InputKind.EOF){
 627                                 if (mode == ParseMode.ReportErrors)
 628                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 629                                 partial_input = true;
 630                                 return null;
 631
 632                         }
 633                         seekable.Position = 0;
 634
 635                         source_file.DeclarationFound = false;
 636                         CSharpParser parser = new CSharpParser (seekable, source_file, new ParserSession ());
 637
 638                         if (kind == InputKind.StatementOrExpression){
 639                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 640                                 parser.Lexer.parsing_block++;
 641                                 ctx.Settings.StatementMode = true;
 642                         } else {
 643                                 parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 644                                 ctx.Settings.StatementMode = false;
 645                         }
 646
 647                         if (mode == ParseMode.GetCompletions)
 648                                 parser.Lexer.CompleteOnEOF = true;
 649
 650                         ReportPrinter old_printer = null;
 651                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions))
 652                                 old_printer = ctx.Report.SetPrinter (new StreamReportPrinter (TextWriter.Null));
 653
 654                         try {
 655                                 parser.parse ();
 656                         } finally {
 657                                 if (ctx.Report.Errors != 0){
 658                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 659                                                 partial_input = true;
 660
 661                                         if (parser.undo != null)
 662                                                 parser.undo.ExecuteUndo ();
 663
 664                                         parser = null;
 665                                 }
 666
 667                                 if (old_printer != null)
 668                                         ctx.Report.SetPrinter (old_printer);
 669                         }
 670                         return parser;
 671                 }
 672
 673                 CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
 674                 {
 675 #if STATIC
 676                         throw new NotSupportedException ();
 677 #else
 678                         string current_debug_name = "eval-" + count + ".dll";
 679                         ++count;
 680
 681                         AssemblyDefinitionDynamic assembly;
 682                         AssemblyBuilderAccess access;
 683
 684                         if (Environment.GetEnvironmentVariable ("SAVE") != null) {
 685                                 access = AssemblyBuilderAccess.RunAndSave;
 686                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name, current_debug_name);
 687                                 assembly.Importer = importer;
 688                         } else {
 689 #if NET_4_0
 690                                 access = AssemblyBuilderAccess.RunAndCollect;
 691 #else
 692                                 access = AssemblyBuilderAccess.Run;
 693 #endif
 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                         StringBuilder sb = new StringBuilder ();
 860                         // TODO:
 861                         //foreach (object x in ns.using_alias_list)
 862                         //    sb.AppendFormat ("using {0};\n", x);
 863
 864                         foreach (var ue in source_file.Usings) {
 865                                 sb.AppendFormat ("using {0};", ue.ToString ());
 866                                 sb.Append (Environment.NewLine);
 867                         }
 868
 869                         return sb.ToString ();
 870                 }
 871
 872                 internal List<string> GetUsingList ()
 873                 {
 874                         var res = new List<string> ();
 875
 876                         foreach (var ue in source_file.Usings) {
 877                                 if (ue.Alias != null || ue.ResolvedExpression == null)
 878                                         continue;
 879
 880                                 res.Add (ue.NamespaceExpression.Name);
 881                         }
 882
 883                         return res;
 884                 }
 885
 886                 internal string [] GetVarNames ()
 887                 {
 888                         lock (evaluator_lock){
 889                                 return new List<string> (fields.Keys).ToArray ();
 890                         }
 891                 }
 892
 893                 public string GetVars ()
 894                 {
 895                         lock (evaluator_lock){
 896                                 StringBuilder sb = new StringBuilder ();
 897
 898                                 foreach (var de in fields){
 899                                         var fi = LookupField (de.Key);
 900                                         object value;
 901                                         try {
 902                                                 value = fi.Item2.GetValue (null);
 903                                                 if (value is string)
 904                                                         value = Quote ((string)value);
 905                                         } catch {
 906                                                 value = "<error reading value>";
 907                                         }
 908
 909                                         sb.AppendFormat ("{0} {1} = {2}", fi.Item1.MemberType.GetSignatureForError (), de.Key, value);
 910                                         sb.AppendLine ();
 911                                 }
 912
 913                                 return sb.ToString ();
 914                         }
 915                 }
 916
 917                 /// <summary>
 918                 ///    Loads the given assembly and exposes the API to the user.
 919                 /// </summary>
 920                 public void LoadAssembly (string file)
 921                 {
 922                         var loader = new DynamicLoader (importer, ctx);
 923                         var assembly = loader.LoadAssemblyFile (file, false);
 924                         if (assembly == null)
 925                                 return;
 926
 927                         lock (evaluator_lock){
 928                                 importer.ImportAssembly (assembly, module.GlobalRootNamespace);
 929                         }
 930                 }
 931
 932                 /// <summary>
 933                 ///    Exposes the API of the given assembly to the Evaluator
 934                 /// </summary>
 935                 public void ReferenceAssembly (Assembly a)
 936                 {
 937                         lock (evaluator_lock){
 938                                 importer.ImportAssembly (a, module.GlobalRootNamespace);
 939                         }
 940                 }
 941         }
 942
 943
 944         /// <summary>
 945         ///   A delegate that can be used to invoke the
 946         ///   compiled expression or statement.
 947         /// </summary>
 948         /// <remarks>
 949         ///   Since the Compile methods will compile
 950         ///   statements and expressions into the same
 951         ///   delegate, you can tell if a value was returned
 952         ///   by checking whether the returned value is of type
 953         ///   NoValueSet.
 954         /// </remarks>
 955
 956         public delegate void CompiledMethod (ref object retvalue);
 957
 958         /// <summary>
 959         ///   The default base class for every interaction line
 960         /// </summary>
 961         /// <remarks>
 962         ///   The expressions and statements behave as if they were
 963         ///   a static method of this class.   The InteractiveBase class
 964         ///   contains a number of useful methods, but can be overwritten
 965         ///   by setting the InteractiveBaseType property in the Evaluator
 966         /// </remarks>
 967         public class InteractiveBase {
 968                 /// <summary>
 969                 ///   Determines where the standard output of methods in this class will go.
 970                 /// </summary>
 971                 public static TextWriter Output = Console.Out;
 972
 973                 /// <summary>
 974                 ///   Determines where the standard error of methods in this class will go.
 975                 /// </summary>
 976                 public static TextWriter Error = Console.Error;
 977
 978                 /// <summary>
 979                 ///   The primary prompt used for interactive use.
 980                 /// </summary>
 981                 public static string Prompt             = "csharp> ";
 982
 983                 /// <summary>
 984                 ///   The secondary prompt used for interactive use (used when
 985                 ///   an expression is incomplete).
 986                 /// </summary>
 987                 public static string ContinuationPrompt = "      > ";
 988
 989                 /// <summary>
 990                 ///   Used to signal that the user has invoked the  `quit' statement.
 991                 /// </summary>
 992                 public static bool QuitRequested;
 993
 994                 public static Evaluator Evaluator;
 995
 996                 /// <summary>
 997                 ///   Shows all the variables defined so far.
 998                 /// </summary>
 999                 static public void ShowVars ()
1000                 {
1001                         Output.Write (Evaluator.GetVars ());
1002                         Output.Flush ();
1003                 }
1004
1005                 /// <summary>
1006                 ///   Displays the using statements in effect at this point.
1007                 /// </summary>
1008                 static public void ShowUsing ()
1009                 {
1010                         Output.Write (Evaluator.GetUsing ());
1011                         Output.Flush ();
1012                 }
1013
1014                 /// <summary>
1015                 ///   Times the execution of the given delegate
1016                 /// </summary>
1017                 static public TimeSpan Time (Action a)
1018                 {
1019                         DateTime start = DateTime.Now;
1020                         a ();
1021                         return DateTime.Now - start;
1022                 }
1023
1024                 /// <summary>
1025                 ///   Loads the assemblies from a package
1026                 /// </summary>
1027                 /// <remarks>
1028                 ///   Loads the assemblies from a package.   This is equivalent
1029                 ///   to passing the -pkg: command line flag to the C# compiler
1030                 ///   on the command line.
1031                 /// </remarks>
1032                 static public void LoadPackage (string pkg)
1033                 {
1034                         if (pkg == null){
1035                                 Error.WriteLine ("Invalid package specified");
1036                                 return;
1037                         }
1038
1039                         string pkgout = Driver.GetPackageFlags (pkg, null);
1040
1041                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
1042                                 Split (new Char [] { ' ', '\t'});
1043
1044                         foreach (string s in xargs){
1045                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
1046                                         string lib = s.Substring (s.IndexOf (':')+1);
1047
1048                                         Evaluator.LoadAssembly (lib);
1049                                         continue;
1050                                 }
1051                         }
1052                 }
1053
1054                 /// <summary>
1055                 ///   Loads the assembly
1056                 /// </summary>
1057                 /// <remarks>
1058                 ///   Loads the specified assembly and makes its types
1059                 ///   available to the evaluator.  This is equivalent
1060                 ///   to passing the -pkg: command line flag to the C#
1061                 ///   compiler on the command line.
1062                 /// </remarks>
1063                 static public void LoadAssembly (string assembly)
1064                 {
1065                         Evaluator.LoadAssembly (assembly);
1066                 }
1067
1068                 static public void print (object obj)
1069                 {
1070                         Output.WriteLine (obj);
1071                 }
1072
1073                 static public void print (string fmt, params object [] args)
1074                 {
1075                         Output.WriteLine (fmt, args);
1076                 }
1077
1078                 /// <summary>
1079                 ///   Returns a list of available static methods.
1080                 /// </summary>
1081                 static public string help {
1082                         get {
1083                                 return "Static methods:\n" +
1084                                         "  Describe (object);       - Describes the object's type\n" +
1085                                         "  LoadPackage (package);   - Loads the given Package (like -pkg:FILE)\n" +
1086                                         "  LoadAssembly (assembly); - Loads the given assembly (like -r:ASSEMBLY)\n" +
1087                                         "  ShowVars ();             - Shows defined local variables.\n" +
1088                                         "  ShowUsing ();            - Show active using declarations.\n" +
1089                                         "  Prompt                   - The prompt used by the C# shell\n" +
1090                                         "  ContinuationPrompt       - The prompt for partial input\n" +
1091                                         "  Time (() => { });        - Times the specified code\n" +
1092                                         "  print (obj);             - Shorthand for Console.WriteLine\n" +
1093                                         "  quit;                    - You'll never believe it - this quits the repl!\n" +
1094                                         "  help;                    - This help text\n";
1095                         }
1096                 }
1097
1098                 /// <summary>
1099                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1100                 /// </summary>
1101                 static public object quit {
1102                         get {
1103                                 QuitRequested = true;
1104
1105                                 // To avoid print null at the exit
1106                                 return typeof (Evaluator.QuitValue);
1107                         }
1108                 }
1109
1110                 /// <summary>
1111                 ///   Same as quit - useful in script scenerios
1112                 /// </summary>
1113                 static public void Quit () {
1114                         QuitRequested = true;
1115                 }
1116
1117 #if !NET_2_1
1118                 /// <summary>
1119                 ///   Describes an object or a type.
1120                 /// </summary>
1121                 /// <remarks>
1122                 ///   This method will show a textual representation
1123                 ///   of the object's type.  If the object is a
1124                 ///   System.Type it renders the type directly,
1125                 ///   otherwise it renders the type returned by
1126                 ///   invoking GetType on the object.
1127                 /// </remarks>
1128                 static public string Describe (object x)
1129                 {
1130                         if (x == null)
1131                                 return "<null>";
1132
1133                         var type = x as Type ?? x.GetType ();
1134
1135                         StringWriter sw = new StringWriter ();
1136                         new Outline (type, sw, true, false, false).OutlineType ();
1137                         return sw.ToString ();
1138                 }
1139 #endif
1140         }
1141
1142         class InteractiveMethod : Method
1143         {
1144                 public InteractiveMethod(TypeDefinition parent, FullNamedExpression returnType, Modifiers mod, ParametersCompiled parameters)
1145                         : base(parent, returnType, mod, new MemberName("Host"), parameters, null)
1146                 {
1147                 }
1148
1149                 public void ChangeToAsync ()
1150                 {
1151                         ModFlags |= Modifiers.ASYNC;
1152                         ModFlags &= ~Modifiers.UNSAFE;
1153                         type_expr = new TypeExpression(Module.PredefinedTypes.Task.TypeSpec, Location);
1154                         parameters = ParametersCompiled.EmptyReadOnlyParameters;
1155                 }
1156
1157                 public override string GetSignatureForError()
1158                 {
1159                         return "InteractiveHost";
1160                 }
1161         }
1162
1163         class HoistedEvaluatorVariable : HoistedVariable
1164         {
1165                 public HoistedEvaluatorVariable (Field field)
1166                         : base (null, field)
1167                 {
1168                 }
1169
1170                 protected override FieldExpr GetFieldExpression (EmitContext ec)
1171                 {
1172                         return new FieldExpr (field, field.Location);
1173                 }
1174         }
1175
1176         /// <summary>
1177         ///    A class used to assign values if the source expression is not void
1178         ///
1179         ///    Used by the interactive shell to allow it to call this code to set
1180         ///    the return value for an invocation.
1181         /// </summary>
1182         class OptionalAssign : SimpleAssign {
1183                 public OptionalAssign (Expression s, Location loc)
1184                         : base (null, s, loc)
1185                 {
1186                 }
1187
1188                 public override Location StartLocation {
1189                         get {
1190                                 return Location.Null;
1191                         }
1192                 }
1193
1194                 protected override Expression DoResolve (ResolveContext ec)
1195                 {
1196                         Expression clone = source.Clone (new CloneContext ());
1197
1198                         clone = clone.Resolve (ec);
1199                         if (clone == null)
1200                                 return null;
1201
1202                         //
1203                         // A useful feature for the REPL: if we can resolve the expression
1204                         // as a type, Describe the type;
1205                         //
1206                         if (ec.Module.Evaluator.DescribeTypeExpressions && !(ec.CurrentAnonymousMethod is AsyncInitializer)) {
1207                                 var old_printer = ec.Report.SetPrinter (new SessionReportPrinter ());
1208                                 Expression tclone;
1209                                 try {
1210                                         // Note: clone context cannot be shared otherwise block mapping would leak
1211                                         tclone = source.Clone (new CloneContext ());
1212                                         tclone = tclone.Resolve (ec, ResolveFlags.Type);
1213                                         if (ec.Report.Errors > 0)
1214                                                 tclone = null;
1215                                 } finally {
1216                                         ec.Report.SetPrinter (old_printer);
1217                                 }
1218
1219                                 if (tclone is TypeExpr) {
1220                                         Arguments args = new Arguments (1);
1221                                         args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
1222                                         return new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
1223                                 }
1224                         }
1225
1226                         // This means its really a statement.
1227                         if (clone.Type.Kind == MemberKind.Void || clone is DynamicInvocation || clone is Assign) {
1228                                 return clone;
1229                         }
1230
1231                         source = clone;
1232
1233                         var host = (Method) ec.MemberContext.CurrentMemberDefinition;
1234
1235                         if (host.ParameterInfo.IsEmpty) {
1236                                 eclass = ExprClass.Value;
1237                                 type = InternalType.FakeInternalType;
1238                                 return this;
1239                         }
1240
1241                         target = new SimpleName (host.ParameterInfo[0].Name, Location);
1242
1243                         return base.DoResolve (ec);
1244                 }
1245
1246                 public override void EmitStatement(EmitContext ec)
1247                 {
1248                         if (target == null) {
1249                                 source.Emit (ec);
1250                                 return;
1251                         }
1252
1253                         base.EmitStatement(ec);
1254                 }
1255         }
1256
1257         public class Undo
1258         {
1259                 List<Action> undo_actions;
1260
1261                 public void AddTypeContainer (TypeContainer current_container, TypeDefinition tc)
1262                 {
1263                         if (current_container == tc){
1264                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1265                                 return;
1266                         }
1267
1268                         if (undo_actions == null)
1269                                 undo_actions = new List<Action> ();
1270
1271                         if (current_container.Containers != null)
1272                         {
1273                                 var existing = current_container.Containers.FirstOrDefault (l => l.Basename == tc.Basename);
1274                                 if (existing != null) {
1275                                         current_container.RemoveContainer (existing);
1276                                         undo_actions.Add (() => current_container.AddTypeContainer (existing));
1277                                 }
1278                         }
1279
1280                         undo_actions.Add (() => current_container.RemoveContainer (tc));
1281                 }
1282
1283                 public void ExecuteUndo ()
1284                 {
1285                         if (undo_actions == null)
1286                                 return;
1287
1288                         foreach (var p in undo_actions){
1289                                 p ();
1290                         }
1291
1292                         undo_actions = null;
1293                 }
1294         }
1295
1296         static class ListenerProxy
1297         {
1298                 static readonly Dictionary<int, Action<string, int, int, object>> listeners = new Dictionary<int, Action<string, int, int, object>> ();
1299
1300                 static int counter;
1301
1302                 public static int Register (Action<string, int, int, object> listener)
1303                 {
1304                         lock (listeners) {
1305                                 var id = counter++;
1306                                 listeners.Add (id, listener);
1307                                 return id;
1308                         }
1309                 }
1310
1311                 public static void Unregister (int listenerId)
1312                 {
1313                         lock (listeners) {
1314                                 listeners.Remove (listenerId);
1315                         }
1316                 }
1317
1318                 public static void ValueChanged (object value, int row, int col, string name, int listenerId)
1319                 {
1320                         Action<string, int, int, object> action;
1321                         lock (listeners) {
1322                                 if (!listeners.TryGetValue (listenerId, out action))
1323                                         return;
1324                         }
1325
1326                         action (name, row, col, value);
1327                 }
1328         }
1329 }