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 #if NET_4_0
 419                                 var access = AssemblyBuilderAccess.RunAndCollect;
 420 #else
 421                                 var access = AssemblyBuilderAccess.Run;
 422 #endif
 423                                 var a = new AssemblyDefinitionDynamic (module, "completions");
 424                                 a.Create (AppDomain.CurrentDomain, access);
 425                                 module.SetDeclaringAssembly (a);
 426
 427                                 // Need to setup MemberCache
 428                                 host.CreateContainer ();
 429                                 // Need to setup base type
 430                                 host.DefineContainer ();
 431
 432                                 var method = host.Members[0] as Method;
 433                                 BlockContext bc = new BlockContext (method, method.Block, ctx.BuiltinTypes.Void);
 434
 435                                 try {
 436                                         method.Block.Resolve (bc, method);
 437                                 } catch (CompletionResult cr) {
 438                                         prefix = cr.BaseText;
 439                                         return cr.Result;
 440                                 }
 441                         }
 442                         return null;
 443                 }
 444
 445                 /// <summary>
 446                 ///   Executes the given expression or statement.
 447                 /// </summary>
 448                 /// <remarks>
 449                 ///    Executes the provided statement, returns true
 450                 ///    on success, false on parsing errors.  Exceptions
 451                 ///    might be thrown by the called code.
 452                 /// </remarks>
 453                 public bool Run (string statement)
 454                 {
 455                         object result;
 456                         bool result_set;
 457
 458                         return Evaluate (statement, out result, out result_set) == null;
 459                 }
 460
 461                 /// <summary>
 462                 ///   Evaluates and expression or statement and returns the result.
 463                 /// </summary>
 464                 /// <remarks>
 465                 ///   Evaluates the input string as a C# expression or
 466                 ///   statement and returns the value.
 467                 ///
 468                 ///   This method will throw an exception if there is a syntax error,
 469                 ///   of if the provided input is not an expression but a statement.
 470                 /// </remarks>
 471                 public object Evaluate (string input)
 472                 {
 473                         object result;
 474                         bool result_set;
 475
 476                         string r = Evaluate (input, out result, out result_set);
 477
 478                         if (r != null)
 479                                 throw new ArgumentException ("Syntax error on input: partial input");
 480
 481                         if (result_set == false)
 482                                 throw new ArgumentException ("The expression failed to resolve");
 483
 484                         return result;
 485                 }
 486
 487                 /// <summary>
 488                 /// Experimental!
 489                 /// </summary>
 490                 public ValueModificationHandler ModificationListener { get; set; }
 491
 492                 enum InputKind {
 493                         EOF,
 494                         StatementOrExpression,
 495                         CompilationUnit,
 496                         Error
 497                 }
 498
 499                 //
 500                 // Deambiguates the input string to determine if we
 501                 // want to process a statement or if we want to
 502                 // process a compilation unit.
 503                 //
 504                 // This is done using a top-down predictive parser,
 505                 // since the yacc/jay parser can not deambiguage this
 506                 // without more than one lookahead token.   There are very
 507                 // few ambiguities.
 508                 //
 509                 InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 510                 {
 511                         Tokenizer tokenizer = new Tokenizer (seekable, source_file, new ParserSession (), ctx.Report);
 512
 513                         // Prefer contextual block keywords over identifiers
 514                         tokenizer.parsing_block++;
 515
 516                         int t = tokenizer.token ();
 517                         switch (t){
 518                         case Token.EOF:
 519                                 return InputKind.EOF;
 520
 521                         // These are toplevels
 522                         case Token.EXTERN:
 523                         case Token.OPEN_BRACKET:
 524                         case Token.OPEN_BRACKET_EXPR:
 525                         case Token.ABSTRACT:
 526                         case Token.CLASS:
 527                         case Token.ENUM:
 528                         case Token.INTERFACE:
 529                         case Token.INTERNAL:
 530                         case Token.NAMESPACE:
 531                         case Token.PRIVATE:
 532                         case Token.PROTECTED:
 533                         case Token.PUBLIC:
 534                         case Token.SEALED:
 535                         case Token.STATIC:
 536                         case Token.STRUCT:
 537                                 return InputKind.CompilationUnit;
 538
 539                         // Definitely expression
 540                         case Token.FIXED:
 541                         case Token.BOOL:
 542                         case Token.BYTE:
 543                         case Token.CHAR:
 544                         case Token.DECIMAL:
 545                         case Token.DOUBLE:
 546                         case Token.FLOAT:
 547                         case Token.INT:
 548                         case Token.LONG:
 549                         case Token.NEW:
 550                         case Token.OBJECT:
 551                         case Token.SBYTE:
 552                         case Token.SHORT:
 553                         case Token.STRING:
 554                         case Token.UINT:
 555                         case Token.ULONG:
 556                                 return InputKind.StatementOrExpression;
 557
 558                         // These need deambiguation help
 559                         case Token.USING:
 560                                 t = tokenizer.token ();
 561                                 if (t == Token.EOF)
 562                                         return InputKind.EOF;
 563
 564                                 if (t == Token.IDENTIFIER || t == Token.STATIC)
 565                                         return InputKind.CompilationUnit;
 566                                 return InputKind.StatementOrExpression;
 567
 568
 569                         // Distinguish between:
 570                         //    delegate opt_anonymous_method_signature block
 571                         //    delegate type
 572                         case Token.DELEGATE:
 573                                 t = tokenizer.token ();
 574                                 if (t == Token.EOF)
 575                                         return InputKind.EOF;
 576                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 577                                         return InputKind.StatementOrExpression;
 578                                 return InputKind.CompilationUnit;
 579
 580                         // Distinguih between:
 581                         //    unsafe block
 582                         //    unsafe as modifier of a type declaration
 583                         case Token.UNSAFE:
 584                                 t = tokenizer.token ();
 585                                 if (t == Token.EOF)
 586                                         return InputKind.EOF;
 587                                 if (t == Token.OPEN_PARENS)
 588                                         return InputKind.StatementOrExpression;
 589                                 return InputKind.CompilationUnit;
 590
 591                         // These are errors: we list explicitly what we had
 592                         // from the grammar, ERROR and then everything else
 593
 594                         case Token.READONLY:
 595                         case Token.OVERRIDE:
 596                         case Token.ERROR:
 597                                 return InputKind.Error;
 598
 599                         // This catches everything else allowed by
 600                         // expressions.  We could add one-by-one use cases
 601                         // if needed.
 602                         default:
 603                                 return InputKind.StatementOrExpression;
 604                         }
 605                 }
 606
 607                 //
 608                 // Parses the string @input and returns a CSharpParser if succeeful.
 609                 //
 610                 // if @silent is set to true then no errors are
 611                 // reported to the user.  This is used to do various calls to the
 612                 // parser and check if the expression is parsable.
 613                 //
 614                 // @partial_input: if @silent is true, then it returns whether the
 615                 // parsed expression was partial, and more data is needed
 616                 //
 617                 CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 618                 {
 619                         partial_input = false;
 620                         Reset ();
 621
 622                         var enc = ctx.Settings.Encoding;
 623                         var s = new MemoryStream (enc.GetBytes (input));
 624                         SeekableStreamReader seekable = new SeekableStreamReader (s, enc);
 625
 626                         InputKind kind = ToplevelOrStatement (seekable);
 627                         if (kind == InputKind.Error){
 628                                 if (mode == ParseMode.ReportErrors)
 629                                         ctx.Report.Error (-25, "Detection Parsing Error");
 630                                 partial_input = false;
 631                                 return null;
 632                         }
 633
 634                         if (kind == InputKind.EOF){
 635                                 if (mode == ParseMode.ReportErrors)
 636                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 637                                 partial_input = true;
 638                                 return null;
 639
 640                         }
 641                         seekable.Position = 0;
 642
 643                         source_file.DeclarationFound = false;
 644                         CSharpParser parser = new CSharpParser (seekable, source_file, new ParserSession ());
 645
 646                         if (kind == InputKind.StatementOrExpression){
 647                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 648                                 parser.Lexer.parsing_block++;
 649                                 ctx.Settings.StatementMode = true;
 650                         } else {
 651                                 parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 652                                 ctx.Settings.StatementMode = false;
 653                         }
 654
 655                         if (mode == ParseMode.GetCompletions)
 656                                 parser.Lexer.CompleteOnEOF = true;
 657
 658                         ReportPrinter old_printer = null;
 659                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions))
 660                                 old_printer = ctx.Report.SetPrinter (new StreamReportPrinter (TextWriter.Null));
 661
 662                         try {
 663                                 parser.parse ();
 664                         } finally {
 665                                 if (ctx.Report.Errors != 0){
 666                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 667                                                 partial_input = true;
 668
 669                                         if (parser.undo != null)
 670                                                 parser.undo.ExecuteUndo ();
 671
 672                                         parser = null;
 673                                 }
 674
 675                                 if (old_printer != null)
 676                                         ctx.Report.SetPrinter (old_printer);
 677                         }
 678                         return parser;
 679                 }
 680
 681                 CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
 682                 {
 683 #if STATIC
 684                         throw new NotSupportedException ();
 685 #else
 686                         string current_debug_name = "eval-" + count + ".dll";
 687                         ++count;
 688
 689                         AssemblyDefinitionDynamic assembly;
 690                         AssemblyBuilderAccess access;
 691
 692                         if (Environment.GetEnvironmentVariable ("SAVE") != null) {
 693                                 access = AssemblyBuilderAccess.RunAndSave;
 694                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name, current_debug_name);
 695                                 assembly.Importer = importer;
 696                         } else {
 697 #if NET_4_0
 698                                 access = AssemblyBuilderAccess.RunAndCollect;
 699 #else
 700                                 access = AssemblyBuilderAccess.Run;
 701 #endif
 702                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name);
 703                         }
 704
 705                         assembly.Create (AppDomain.CurrentDomain, access);
 706
 707                         Method expression_method;
 708                         if (host != null) {
 709                                 var base_class_imported = importer.ImportType (base_class);
 710                                 var baseclass_list = new List<FullNamedExpression> (1) {
 711                                         new TypeExpression (base_class_imported, host.Location)
 712                                 };
 713
 714                                 host.SetBaseTypes (baseclass_list);
 715
 716                                 expression_method = (Method) host.Members[0];
 717
 718                                 if ((expression_method.ModFlags & Modifiers.ASYNC) != 0) {
 719                                         //
 720                                         // Host method is async. When WaitOnTask is set we wrap it with wait
 721                                         //
 722                                         // void AsyncWait (ref object $retval) {
 723                                         //      $retval = Host();
 724                                         //      ((Task)$retval).Wait();  // When WaitOnTask is set
 725                                         // }
 726                                         //
 727                                         var p = new ParametersCompiled (
 728                                                 new Parameter (new TypeExpression (module.Compiler.BuiltinTypes.Object, Location.Null), "$retval", Parameter.Modifier.REF, null, Location.Null)
 729                                         );
 730
 731                                         var method = new Method(host, new TypeExpression(module.Compiler.BuiltinTypes.Void, Location.Null),
 732                                                 Modifiers.PUBLIC | Modifiers.STATIC, new MemberName("AsyncWait"), p, null);
 733
 734                                         method.Block = new ToplevelBlock(method.Compiler, p, Location.Null);
 735                                         method.Block.AddStatement(new StatementExpression (new SimpleAssign(
 736                                                 new SimpleName(p [0].Name, Location.Null),
 737                                                 new Invocation(new SimpleName(expression_method.MemberName.Name, Location.Null), new Arguments(0)),
 738                                                 Location.Null), Location.Null));
 739
 740                                         if (WaitOnTask) {
 741                                                 var task = new Cast (expression_method.TypeExpression, new SimpleName (p [0].Name, Location.Null), Location.Null);
 742
 743                                                 method.Block.AddStatement (new StatementExpression (new Invocation (
 744                                                                 new MemberAccess (task, "Wait", Location.Null),
 745                                                         new Arguments (0)), Location.Null));
 746                                         }
 747
 748                                         host.AddMember(method);
 749
 750                                         expression_method = method;
 751                                 }
 752
 753                                 host.CreateContainer();
 754                                 host.DefineContainer();
 755                                 host.Define();
 756
 757                         } else {
 758                                 expression_method = null;
 759                         }
 760
 761                         module.CreateContainer ();
 762
 763                         // Disable module and source file re-definition checks
 764                         module.EnableRedefinition ();
 765                         source_file.EnableRedefinition ();
 766
 767                         module.Define ();
 768
 769                         if (Report.Errors != 0){
 770                                 if (undo != null)
 771                                         undo.ExecuteUndo ();
 772
 773                                 return null;
 774                         }
 775
 776                         if (host != null){
 777                                 host.PrepareEmit ();
 778                                 host.EmitContainer ();
 779                         }
 780
 781                         module.EmitContainer ();
 782
 783                         if (Report.Errors != 0){
 784                                 if (undo != null)
 785                                         undo.ExecuteUndo ();
 786                                 return null;
 787                         }
 788
 789                         module.CloseContainer ();
 790                         if (host != null)
 791                                 host.CloseContainer ();
 792
 793                         if (access == AssemblyBuilderAccess.RunAndSave)
 794                                 assembly.Save ();
 795
 796                         if (host == null)
 797                                 return null;
 798
 799                         //
 800                         // Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
 801                         // work from MethodBuilders.   Retarded, I know.
 802                         //
 803                         var tt = assembly.Builder.GetType (host.TypeBuilder.Name);
 804                         var mi = tt.GetMethod (expression_method.MemberName.Name);
 805
 806                         //
 807                         // We need to then go from FieldBuilder to FieldInfo
 808                         // or reflection gets confused (it basically gets confused, and variables override each
 809                         // other).
 810                         //
 811                         foreach (var member in host.Members) {
 812                                 var field = member as Field;
 813                                 if (field == null)
 814                                         continue;
 815
 816                                 var fi = tt.GetField (field.Name);
 817
 818                                 Tuple<FieldSpec, FieldInfo> old;
 819
 820                                 // If a previous value was set, nullify it, so that we do
 821                                 // not leak memory
 822                                 if (fields.TryGetValue (field.Name, out old)) {
 823                                         if (old.Item1.MemberType.IsStruct) {
 824                                                 //
 825                                                 // TODO: Clear fields for structs
 826                                                 //
 827                                         } else {
 828                                                 try {
 829                                                         old.Item2.SetValue (null, null);
 830                                                 } catch {
 831                                                 }
 832                                         }
 833                                 }
 834
 835                                 fields[field.Name] = Tuple.Create (field.Spec, fi);
 836                         }
 837
 838                         return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
 839 #endif
 840                 }
 841
 842                 /// <summary>
 843                 ///   A sentinel value used to indicate that no value was
 844                 ///   was set by the compiled function.   This is used to
 845                 ///   differentiate between a function not returning a
 846                 ///   value and null.
 847                 /// </summary>
 848                 internal static class QuitValue { }
 849
 850                 internal Tuple<FieldSpec, FieldInfo> LookupField (string name)
 851                 {
 852                         Tuple<FieldSpec, FieldInfo> fi;
 853                         fields.TryGetValue (name, out fi);
 854                         return fi;
 855                 }
 856
 857                 static string Quote (string s)
 858                 {
 859                         if (s.IndexOf ('"') != -1)
 860                                 s = s.Replace ("\"", "\\\"");
 861
 862                         return "\"" + s + "\"";
 863                 }
 864
 865                 public string GetUsing ()
 866                 {
 867                         if (source_file == null || source_file.Usings == null)
 868                                 return string.Empty;
 869
 870                         StringBuilder sb = new StringBuilder ();
 871                         // TODO:
 872                         //foreach (object x in ns.using_alias_list)
 873                         //    sb.AppendFormat ("using {0};\n", x);
 874
 875                         foreach (var ue in source_file.Usings) {
 876                                 if (ue.Alias != null || ue.ResolvedExpression == null)
 877                                         continue;
 878
 879                                 sb.AppendFormat("using {0};", ue.ToString ());
 880                                 sb.Append (Environment.NewLine);
 881                         }
 882
 883                         return sb.ToString ();
 884                 }
 885
 886                 internal List<string> GetUsingList ()
 887                 {
 888                         var res = new List<string> ();
 889
 890                         if (source_file == null || source_file.Usings == null)
 891                                 return res;
 892
 893                         foreach (var ue in source_file.Usings)
 894                         {
 895                                 if (ue.Alias != null || ue.ResolvedExpression == null)
 896                                         continue;
 897
 898                                 res.Add (ue.NamespaceExpression.Name);
 899                         }
 900
 901                         return res;
 902                 }
 903
 904                 internal string [] GetVarNames ()
 905                 {
 906                         lock (evaluator_lock){
 907                                 return new List<string> (fields.Keys).ToArray ();
 908                         }
 909                 }
 910
 911                 public string GetVars ()
 912                 {
 913                         lock (evaluator_lock){
 914                                 StringBuilder sb = new StringBuilder ();
 915
 916                                 foreach (var de in fields){
 917                                         var fi = LookupField (de.Key);
 918                                         object value;
 919                                         try {
 920                                                 value = fi.Item2.GetValue (null);
 921                                                 if (value is string)
 922                                                         value = Quote ((string)value);
 923                                         } catch {
 924                                                 value = "<error reading value>";
 925                                         }
 926
 927                                         sb.AppendFormat ("{0} {1} = {2}", fi.Item1.MemberType.GetSignatureForError (), de.Key, value);
 928                                         sb.AppendLine ();
 929                                 }
 930
 931                                 return sb.ToString ();
 932                         }
 933                 }
 934
 935                 /// <summary>
 936                 ///    Loads the given assembly and exposes the API to the user.
 937                 /// </summary>
 938                 public void LoadAssembly (string file)
 939                 {
 940                         var loader = new DynamicLoader (importer, ctx);
 941                         var assembly = loader.LoadAssemblyFile (file, false);
 942                         if (assembly == null)
 943                                 return;
 944
 945                         lock (evaluator_lock){
 946                                 importer.ImportAssembly (assembly, module.GlobalRootNamespace);
 947                         }
 948                 }
 949
 950                 /// <summary>
 951                 ///    Exposes the API of the given assembly to the Evaluator
 952                 /// </summary>
 953                 public void ReferenceAssembly (Assembly a)
 954                 {
 955                         lock (evaluator_lock){
 956                                 importer.ImportAssembly (a, module.GlobalRootNamespace);
 957                         }
 958                 }
 959         }
 960
 961
 962         /// <summary>
 963         ///   A delegate that can be used to invoke the
 964         ///   compiled expression or statement.
 965         /// </summary>
 966         /// <remarks>
 967         ///   Since the Compile methods will compile
 968         ///   statements and expressions into the same
 969         ///   delegate, you can tell if a value was returned
 970         ///   by checking whether the returned value is of type
 971         ///   NoValueSet.
 972         /// </remarks>
 973
 974         public delegate void CompiledMethod (ref object retvalue);
 975
 976         /// <summary>
 977         ///   The default base class for every interaction line
 978         /// </summary>
 979         /// <remarks>
 980         ///   The expressions and statements behave as if they were
 981         ///   a static method of this class.   The InteractiveBase class
 982         ///   contains a number of useful methods, but can be overwritten
 983         ///   by setting the InteractiveBaseType property in the Evaluator
 984         /// </remarks>
 985         public class InteractiveBase {
 986                 /// <summary>
 987                 ///   Determines where the standard output of methods in this class will go.
 988                 /// </summary>
 989                 public static TextWriter Output = Console.Out;
 990
 991                 /// <summary>
 992                 ///   Determines where the standard error of methods in this class will go.
 993                 /// </summary>
 994                 public static TextWriter Error = Console.Error;
 995
 996                 /// <summary>
 997                 ///   The primary prompt used for interactive use.
 998                 /// </summary>
 999                 public static string Prompt             = "csharp> ";
1000
1001                 /// <summary>
1002                 ///   The secondary prompt used for interactive use (used when
1003                 ///   an expression is incomplete).
1004                 /// </summary>
1005                 public static string ContinuationPrompt = "      > ";
1006
1007                 /// <summary>
1008                 ///   Used to signal that the user has invoked the  `quit' statement.
1009                 /// </summary>
1010                 public static bool QuitRequested;
1011
1012                 public static Evaluator Evaluator;
1013
1014                 /// <summary>
1015                 ///   Shows all the variables defined so far.
1016                 /// </summary>
1017                 static public void ShowVars ()
1018                 {
1019                         Output.Write (Evaluator.GetVars ());
1020                         Output.Flush ();
1021                 }
1022
1023                 /// <summary>
1024                 ///   Displays the using statements in effect at this point.
1025                 /// </summary>
1026                 static public void ShowUsing ()
1027                 {
1028                         Output.Write (Evaluator.GetUsing ());
1029                         Output.Flush ();
1030                 }
1031
1032                 /// <summary>
1033                 ///   Times the execution of the given delegate
1034                 /// </summary>
1035                 static public TimeSpan Time (Action a)
1036                 {
1037                         DateTime start = DateTime.Now;
1038                         a ();
1039                         return DateTime.Now - start;
1040                 }
1041
1042                 /// <summary>
1043                 ///   Loads the assemblies from a package
1044                 /// </summary>
1045                 /// <remarks>
1046                 ///   Loads the assemblies from a package.   This is equivalent
1047                 ///   to passing the -pkg: command line flag to the C# compiler
1048                 ///   on the command line.
1049                 /// </remarks>
1050                 static public void LoadPackage (string pkg)
1051                 {
1052                         if (pkg == null){
1053                                 Error.WriteLine ("Invalid package specified");
1054                                 return;
1055                         }
1056
1057                         string pkgout = Driver.GetPackageFlags (pkg, null);
1058
1059                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
1060                                 Split (new Char [] { ' ', '\t'});
1061
1062                         foreach (string s in xargs){
1063                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
1064                                         string lib = s.Substring (s.IndexOf (':')+1);
1065
1066                                         Evaluator.LoadAssembly (lib);
1067                                         continue;
1068                                 }
1069                         }
1070                 }
1071
1072                 /// <summary>
1073                 ///   Loads the assembly
1074                 /// </summary>
1075                 /// <remarks>
1076                 ///   Loads the specified assembly and makes its types
1077                 ///   available to the evaluator.  This is equivalent
1078                 ///   to passing the -pkg: command line flag to the C#
1079                 ///   compiler on the command line.
1080                 /// </remarks>
1081                 static public void LoadAssembly (string assembly)
1082                 {
1083                         Evaluator.LoadAssembly (assembly);
1084                 }
1085
1086                 static public void print (object obj)
1087                 {
1088                         Output.WriteLine (obj);
1089                 }
1090
1091                 static public void print (string fmt, params object [] args)
1092                 {
1093                         Output.WriteLine (fmt, args);
1094                 }
1095
1096                 /// <summary>
1097                 ///   Returns a list of available static methods.
1098                 /// </summary>
1099                 static public string help {
1100                         get {
1101                                 return "Static methods:\n" +
1102                                         "  Describe (object);       - Describes the object's type\n" +
1103                                         "  LoadPackage (package);   - Loads the given Package (like -pkg:FILE)\n" +
1104                                         "  LoadAssembly (assembly); - Loads the given assembly (like -r:ASSEMBLY)\n" +
1105                                         "  ShowVars ();             - Shows defined local variables.\n" +
1106                                         "  ShowUsing ();            - Show active using declarations.\n" +
1107                                         "  Prompt                   - The prompt used by the C# shell\n" +
1108                                         "  ContinuationPrompt       - The prompt for partial input\n" +
1109                                         "  Time (() => { });        - Times the specified code\n" +
1110                                         "  print (obj);             - Shorthand for Console.WriteLine\n" +
1111                                         "  quit;                    - You'll never believe it - this quits the repl!\n" +
1112                                         "  help;                    - This help text\n";
1113                         }
1114                 }
1115
1116                 /// <summary>
1117                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1118                 /// </summary>
1119                 static public object quit {
1120                         get {
1121                                 QuitRequested = true;
1122
1123                                 // To avoid print null at the exit
1124                                 return typeof (Evaluator.QuitValue);
1125                         }
1126                 }
1127
1128                 /// <summary>
1129                 ///   Same as quit - useful in script scenerios
1130                 /// </summary>
1131                 static public void Quit () {
1132                         QuitRequested = true;
1133                 }
1134
1135 #if !NET_2_1
1136                 /// <summary>
1137                 ///   Describes an object or a type.
1138                 /// </summary>
1139                 /// <remarks>
1140                 ///   This method will show a textual representation
1141                 ///   of the object's type.  If the object is a
1142                 ///   System.Type it renders the type directly,
1143                 ///   otherwise it renders the type returned by
1144                 ///   invoking GetType on the object.
1145                 /// </remarks>
1146                 static public string Describe (object x)
1147                 {
1148                         if (x == null)
1149                                 return "<null>";
1150
1151                         var type = x as Type ?? x.GetType ();
1152
1153                         StringWriter sw = new StringWriter ();
1154                         new Outline (type, sw, true, false, false).OutlineType ();
1155                         return sw.ToString ();
1156                 }
1157 #endif
1158         }
1159
1160         class InteractiveMethod : Method
1161         {
1162                 public InteractiveMethod(TypeDefinition parent, FullNamedExpression returnType, Modifiers mod, ParametersCompiled parameters)
1163                         : base(parent, returnType, mod, new MemberName("Host"), parameters, null)
1164                 {
1165                 }
1166
1167                 public void ChangeToAsync ()
1168                 {
1169                         ModFlags |= Modifiers.ASYNC;
1170                         ModFlags &= ~Modifiers.UNSAFE;
1171                         type_expr = new TypeExpression(Module.PredefinedTypes.Task.TypeSpec, Location);
1172                         parameters = ParametersCompiled.EmptyReadOnlyParameters;
1173                 }
1174
1175                 public override string GetSignatureForError()
1176                 {
1177                         return "InteractiveHost";
1178                 }
1179         }
1180
1181         class HoistedEvaluatorVariable : HoistedVariable
1182         {
1183                 public HoistedEvaluatorVariable (Field field)
1184                         : base (null, field)
1185                 {
1186                 }
1187
1188                 protected override FieldExpr GetFieldExpression (EmitContext ec)
1189                 {
1190                         return new FieldExpr (field, field.Location);
1191                 }
1192         }
1193
1194         /// <summary>
1195         ///    A class used to assign values if the source expression is not void
1196         ///
1197         ///    Used by the interactive shell to allow it to call this code to set
1198         ///    the return value for an invocation.
1199         /// </summary>
1200         class OptionalAssign : SimpleAssign {
1201                 public OptionalAssign (Expression s, Location loc)
1202                         : base (null, s, loc)
1203                 {
1204                 }
1205
1206                 public override Location StartLocation {
1207                         get {
1208                                 return Location.Null;
1209                         }
1210                 }
1211
1212                 protected override Expression DoResolve (ResolveContext ec)
1213                 {
1214                         Expression clone = source.Clone (new CloneContext ());
1215
1216                         clone = clone.Resolve (ec);
1217                         if (clone == null)
1218                                 return null;
1219
1220                         //
1221                         // A useful feature for the REPL: if we can resolve the expression
1222                         // as a type, Describe the type;
1223                         //
1224                         if (ec.Module.Evaluator.DescribeTypeExpressions && !(ec.CurrentAnonymousMethod is AsyncInitializer)) {
1225                                 var old_printer = ec.Report.SetPrinter (new SessionReportPrinter ());
1226                                 Expression tclone;
1227                                 try {
1228                                         // Note: clone context cannot be shared otherwise block mapping would leak
1229                                         tclone = source.Clone (new CloneContext ());
1230                                         tclone = tclone.Resolve (ec, ResolveFlags.Type);
1231                                         if (ec.Report.Errors > 0)
1232                                                 tclone = null;
1233                                 } finally {
1234                                         ec.Report.SetPrinter (old_printer);
1235                                 }
1236
1237                                 if (tclone is TypeExpr) {
1238                                         Arguments args = new Arguments (1);
1239                                         args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
1240                                         return new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
1241                                 }
1242                         }
1243
1244                         // This means its really a statement.
1245                         if (clone.Type.Kind == MemberKind.Void || clone is DynamicInvocation || clone is Assign) {
1246                                 return clone;
1247                         }
1248
1249                         source = clone;
1250
1251                         var host = (Method) ec.MemberContext.CurrentMemberDefinition;
1252
1253                         if (host.ParameterInfo.IsEmpty) {
1254                                 eclass = ExprClass.Value;
1255                                 type = InternalType.FakeInternalType;
1256                                 return this;
1257                         }
1258
1259                         target = new SimpleName (host.ParameterInfo[0].Name, Location);
1260
1261                         return base.DoResolve (ec);
1262                 }
1263
1264                 public override void EmitStatement(EmitContext ec)
1265                 {
1266                         if (target == null) {
1267                                 source.Emit (ec);
1268                                 return;
1269                         }
1270
1271                         base.EmitStatement(ec);
1272                 }
1273         }
1274
1275         public class Undo
1276         {
1277                 List<Action> undo_actions;
1278
1279                 public void AddTypeContainer (TypeContainer current_container, TypeDefinition tc)
1280                 {
1281                         if (current_container == tc){
1282                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1283                                 return;
1284                         }
1285
1286                         if (undo_actions == null)
1287                                 undo_actions = new List<Action> ();
1288
1289                         if (current_container.Containers != null)
1290                         {
1291                                 var existing = current_container.Containers.FirstOrDefault (l => l.MemberName.Basename == tc.MemberName.Basename);
1292                                 if (existing != null) {
1293                                         current_container.RemoveContainer (existing);
1294                                         undo_actions.Add (() => current_container.AddTypeContainer (existing));
1295                                 }
1296                         }
1297
1298                         undo_actions.Add (() => current_container.RemoveContainer (tc));
1299                 }
1300
1301                 public void ExecuteUndo ()
1302                 {
1303                         if (undo_actions == null)
1304                                 return;
1305
1306                         foreach (var p in undo_actions){
1307                                 p ();
1308                         }
1309
1310                         undo_actions = null;
1311                 }
1312         }
1313
1314         static class ListenerProxy
1315         {
1316                 static readonly Dictionary<int, ValueModificationHandler> listeners = new Dictionary<int, ValueModificationHandler> ();
1317
1318                 static int counter;
1319
1320                 public static int Register (ValueModificationHandler listener)
1321                 {
1322                         lock (listeners) {
1323                                 var id = counter++;
1324                                 listeners.Add (id, listener);
1325                                 return id;
1326                         }
1327                 }
1328
1329                 public static void Unregister (int listenerId)
1330                 {
1331                         lock (listeners) {
1332                                 listeners.Remove (listenerId);
1333                         }
1334                 }
1335
1336                 public static void ValueChanged (object value, int row, int col, string name, int listenerId)
1337                 {
1338                         ValueModificationHandler action;
1339                         lock (listeners) {
1340                                 if (!listeners.TryGetValue (listenerId, out action))
1341                                         return;
1342                         }
1343
1344                         action (name, row, col, value);
1345                 }
1346         }
1347 }