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                 public Evaluator (CompilerContext ctx)
  76                 {
  77                         this.ctx = ctx;
  78
  79                         module = new ModuleContainer (ctx);
  80                         module.Evaluator = this;
  81
  82                         source_file = new CompilationSourceFile (module, null);
  83                         module.AddTypeContainer (source_file);
  84
  85                         startup_files = ctx.SourceFiles.Count;
  86
  87                         // FIXME: Importer needs this assembly for internalsvisibleto
  88                         module.SetDeclaringAssembly (new AssemblyDefinitionDynamic (module, "evaluator"));
  89                         importer = new ReflectionImporter (module, ctx.BuiltinTypes);
  90
  91                         InteractiveBaseClass = typeof (InteractiveBase);
  92                         fields = new Dictionary<string, Tuple<FieldSpec, FieldInfo>> ();
  93                 }
  94
  95                 void Init ()
  96                 {
  97                         var loader = new DynamicLoader (importer, ctx);
  98
  99                         CompilerCallableEntryPoint.Reset ();
 100                         RootContext.ToplevelTypes = module;
 101
 102                         //var startup_files = new List<string> ();
 103                         //foreach (CompilationUnit file in Location.SourceFiles)
 104                         //    startup_files.Add (file.Path);
 105
 106                         loader.LoadReferences (module);
 107                         ctx.BuiltinTypes.CheckDefinitions (module);
 108                         module.InitializePredefinedTypes ();
 109
 110                         inited = true;
 111                 }
 112
 113                 void ParseStartupFiles ()
 114                 {
 115                         Driver d = new Driver (ctx);
 116
 117                         Location.Initialize (ctx.SourceFiles);
 118
 119                         var parser_session = new ParserSession ();
 120                         for (int i = 0; i < startup_files; ++i) {
 121                                 var sf = ctx.SourceFiles [i];
 122                                 d.Parse (sf, module, parser_session, ctx.Report);
 123                         }
 124                 }
 125
 126                 void Reset ()
 127                 {
 128                         CompilerCallableEntryPoint.PartialReset ();
 129
 130                         Location.Reset ();
 131                         Location.Initialize (ctx.SourceFiles);
 132                 }
 133
 134                 /// <summary>
 135                 /// When set evaluator will automatically wait on Task of async methods. When not
 136                 /// set it's called responsibility to handle Task execution
 137                 /// </summary>
 138                 public bool WaitOnTask { get; set; }
 139
 140                 /// <summary>
 141                 ///   If true, turns type expressions into valid expressions
 142                 ///   and calls the describe method on it
 143                 /// </summary>
 144                 public bool DescribeTypeExpressions;
 145
 146                 /// <summary>
 147                 ///   Whether the evaluator will use terse syntax, and the semicolons at the end are optional
 148                 /// </summary>
 149                 public bool Terse = true;
 150
 151                 /// <summary>
 152                 ///   The base class for the classes that host the user generated code
 153                 /// </summary>
 154                 /// <remarks>
 155                 ///
 156                 ///   This is the base class that will host the code
 157                 ///   executed by the Evaluator.  By default
 158                 ///   this is the Mono.CSharp.InteractiveBase class
 159                 ///   which is useful for interactive use.
 160                 ///
 161                 ///   By changing this property you can control the
 162                 ///   base class and the static members that are
 163                 ///   available to your evaluated code.
 164                 /// </remarks>
 165                 public Type InteractiveBaseClass {
 166                         get {
 167                                 return base_class;
 168                         }
 169                         set {
 170                                 base_class = value;
 171
 172                                 if (value != null && typeof (InteractiveBase).IsAssignableFrom (value))
 173                                         InteractiveBase.Evaluator = this;
 174                         }
 175                 }
 176
 177                 /// <summary>
 178                 ///   Interrupts the evaluation of an expression executing in Evaluate.
 179                 /// </summary>
 180                 /// <remarks>
 181                 ///   Use this method to interrupt long-running invocations.
 182                 /// </remarks>
 183                 public void Interrupt ()
 184                 {
 185                         if (!inited || !invoking)
 186                                 return;
 187
 188                         if (invoke_thread != null)
 189                                 invoke_thread.Abort ();
 190                 }
 191
 192                 /// <summary>
 193                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 194                 /// </summary>
 195                 /// <remarks>
 196                 ///
 197                 ///   Compiles the input string as a C# expression or
 198                 ///   statement, unlike the Evaluate method, the
 199                 ///   resulting delegate can be invoked multiple times
 200                 ///   without incurring in the compilation overhead.
 201                 ///
 202                 ///   If the return value of this function is null,
 203                 ///   this indicates that the parsing was complete.
 204                 ///   If the return value is a string it indicates
 205                 ///   that the input string was partial and that the
 206                 ///   invoking code should provide more code before
 207                 ///   the code can be successfully compiled.
 208                 ///
 209                 ///   If you know that you will always get full expressions or
 210                 ///   statements and do not care about partial input, you can use
 211                 ///   the other Compile overload.
 212                 ///
 213                 ///   On success, in addition to returning null, the
 214                 ///   compiled parameter will be set to the delegate
 215                 ///   that can be invoked to execute the code.
 216                 ///
 217                 /// </remarks>
 218                 public string Compile (string input, out CompiledMethod compiled)
 219                 {
 220                         if (input == null || input.Length == 0){
 221                                 compiled = null;
 222                                 return null;
 223                         }
 224
 225                         lock (evaluator_lock){
 226                                 if (!inited) {
 227                                         Init ();
 228                                         ParseStartupFiles ();
 229                                 } else {
 230                                         ctx.Report.Printer.Reset ();
 231                                 }
 232
 233                                 bool partial_input;
 234                                 CSharpParser parser = ParseString (ParseMode.Silent, input, out partial_input);
 235
 236                                 // Terse mode, try to provide the trailing semicolon automatically.
 237                                 if (parser == null && Terse && partial_input){
 238                                         bool ignore;
 239
 240                                         // check if the source would compile with a block, if so, we should not
 241                                         // add the semicolon.
 242                                         var needs_block = ParseString (ParseMode.Silent, input + "{}", out ignore) != null;
 243                                         if (!needs_block)
 244                                                 parser = ParseString (ParseMode.Silent, input + ";", out ignore);
 245                                 }
 246                                 if (parser == null){
 247                                         compiled = null;
 248                                         if (partial_input)
 249                                                 return input;
 250
 251                                         ParseString (ParseMode.ReportErrors, input, out partial_input);
 252                                         return null;
 253                                 }
 254
 255                                 Class parser_result = parser.InteractiveResult;
 256                                 compiled = CompileBlock (parser_result, parser.undo, ctx.Report);
 257                                 return null;
 258                         }
 259                 }
 260
 261                 /// <summary>
 262                 ///   Compiles the input string and returns a delegate that represents the compiled code.
 263                 /// </summary>
 264                 /// <remarks>
 265                 ///
 266                 ///   Compiles the input string as a C# expression or
 267                 ///   statement, unlike the Evaluate method, the
 268                 ///   resulting delegate can be invoked multiple times
 269                 ///   without incurring in the compilation overhead.
 270                 ///
 271                 ///   This method can only deal with fully formed input
 272                 ///   strings and does not provide a completion mechanism.
 273                 ///   If you must deal with partial input (for example for
 274                 ///   interactive use) use the other overload.
 275                 ///
 276                 ///   On success, a delegate is returned that can be used
 277                 ///   to invoke the method.
 278                 ///
 279                 /// </remarks>
 280                 public CompiledMethod Compile (string input)
 281                 {
 282                         CompiledMethod compiled;
 283
 284                         // Ignore partial inputs
 285                         if (Compile (input, out compiled) != null){
 286                                 // Error, the input was partial.
 287                                 return null;
 288                         }
 289
 290                         // Either null (on error) or the compiled method.
 291                         return compiled;
 292                 }
 293
 294                 /// <summary>
 295                 ///   Evaluates and expression or statement and returns any result values.
 296                 /// </summary>
 297                 /// <remarks>
 298                 ///   Evaluates the input string as a C# expression or
 299                 ///   statement.  If the input string is an expression
 300                 ///   the result will be stored in the result variable
 301                 ///   and the result_set variable will be set to true.
 302                 ///
 303                 ///   It is necessary to use the result/result_set
 304                 ///   pair to identify when a result was set (for
 305                 ///   example, execution of user-provided input can be
 306                 ///   an expression, a statement or others, and
 307                 ///   result_set would only be set if the input was an
 308                 ///   expression.
 309                 ///
 310                 ///   If the return value of this function is null,
 311                 ///   this indicates that the parsing was complete.
 312                 ///   If the return value is a string, it indicates
 313                 ///   that the input is partial and that the user
 314                 ///   should provide an updated string.
 315                 /// </remarks>
 316                 public string Evaluate (string input, out object result, out bool result_set)
 317                 {
 318                         CompiledMethod compiled;
 319
 320                         result_set = false;
 321                         result = null;
 322
 323                         input = Compile (input, out compiled);
 324                         if (input != null)
 325                                 return input;
 326
 327                         if (compiled == null)
 328                                 return null;
 329
 330                         //
 331                         // The code execution does not need to keep the compiler lock
 332                         //
 333                         object retval = typeof (QuitValue);
 334
 335                         try {
 336                                 invoke_thread = System.Threading.Thread.CurrentThread;
 337                                 invoking = true;
 338                                 compiled (ref retval);
 339                         } catch (ThreadAbortException e){
 340                                 Thread.ResetAbort ();
 341                                 Console.WriteLine ("Interrupted!\n{0}", e);
 342                         } finally {
 343                                 invoking = false;
 344                         }
 345
 346                         //
 347                         // We use a reference to a compiler type, in this case
 348                         // Driver as a flag to indicate that this was a statement
 349                         //
 350                         if (!ReferenceEquals (retval, typeof (QuitValue))) {
 351                                 result_set = true;
 352                                 result = retval;
 353                         }
 354
 355                         return null;
 356                 }
 357
 358                 public string [] GetCompletions (string input, out string prefix)
 359                 {
 360                         prefix = "";
 361                         if (input == null || input.Length == 0)
 362                                 return null;
 363
 364                         lock (evaluator_lock){
 365                                 if (!inited)
 366                                         Init ();
 367
 368                                 bool partial_input;
 369                                 CSharpParser parser = ParseString (ParseMode.GetCompletions, input, out partial_input);
 370                                 if (parser == null){
 371                                         return null;
 372                                 }
 373
 374                                 Class parser_result = parser.InteractiveResult;
 375
 376 #if NET_4_0
 377                                 var access = AssemblyBuilderAccess.RunAndCollect;
 378 #else
 379                                 var access = AssemblyBuilderAccess.Run;
 380 #endif
 381                                 var a = new AssemblyDefinitionDynamic (module, "completions");
 382                                 a.Create (AppDomain.CurrentDomain, access);
 383                                 module.SetDeclaringAssembly (a);
 384
 385                                 // Need to setup MemberCache
 386                                 parser_result.CreateContainer ();
 387
 388                                 var method = parser_result.Members[0] as Method;
 389                                 BlockContext bc = new BlockContext (method, method.Block, ctx.BuiltinTypes.Void);
 390
 391                                 try {
 392                                         method.Block.Resolve (bc, method);
 393                                 } catch (CompletionResult cr) {
 394                                         prefix = cr.BaseText;
 395                                         return cr.Result;
 396                                 }
 397                         }
 398                         return null;
 399                 }
 400
 401                 /// <summary>
 402                 ///   Executes the given expression or statement.
 403                 /// </summary>
 404                 /// <remarks>
 405                 ///    Executes the provided statement, returns true
 406                 ///    on success, false on parsing errors.  Exceptions
 407                 ///    might be thrown by the called code.
 408                 /// </remarks>
 409                 public bool Run (string statement)
 410                 {
 411                         object result;
 412                         bool result_set;
 413
 414                         return Evaluate (statement, out result, out result_set) == null;
 415                 }
 416
 417                 /// <summary>
 418                 ///   Evaluates and expression or statement and returns the result.
 419                 /// </summary>
 420                 /// <remarks>
 421                 ///   Evaluates the input string as a C# expression or
 422                 ///   statement and returns the value.
 423                 ///
 424                 ///   This method will throw an exception if there is a syntax error,
 425                 ///   of if the provided input is not an expression but a statement.
 426                 /// </remarks>
 427                 public object Evaluate (string input)
 428                 {
 429                         object result;
 430                         bool result_set;
 431
 432                         string r = Evaluate (input, out result, out result_set);
 433
 434                         if (r != null)
 435                                 throw new ArgumentException ("Syntax error on input: partial input");
 436
 437                         if (result_set == false)
 438                                 throw new ArgumentException ("The expression failed to resolve");
 439
 440                         return result;
 441                 }
 442
 443                 enum InputKind {
 444                         EOF,
 445                         StatementOrExpression,
 446                         CompilationUnit,
 447                         Error
 448                 }
 449
 450                 //
 451                 // Deambiguates the input string to determine if we
 452                 // want to process a statement or if we want to
 453                 // process a compilation unit.
 454                 //
 455                 // This is done using a top-down predictive parser,
 456                 // since the yacc/jay parser can not deambiguage this
 457                 // without more than one lookahead token.   There are very
 458                 // few ambiguities.
 459                 //
 460                 InputKind ToplevelOrStatement (SeekableStreamReader seekable)
 461                 {
 462                         Tokenizer tokenizer = new Tokenizer (seekable, source_file, new ParserSession (), ctx.Report);
 463
 464                         // Prefer contextual block keywords over identifiers
 465                         tokenizer.parsing_block++;
 466
 467                         int t = tokenizer.token ();
 468                         switch (t){
 469                         case Token.EOF:
 470                                 return InputKind.EOF;
 471
 472                         // These are toplevels
 473                         case Token.EXTERN:
 474                         case Token.OPEN_BRACKET:
 475                         case Token.ABSTRACT:
 476                         case Token.CLASS:
 477                         case Token.ENUM:
 478                         case Token.INTERFACE:
 479                         case Token.INTERNAL:
 480                         case Token.NAMESPACE:
 481                         case Token.PRIVATE:
 482                         case Token.PROTECTED:
 483                         case Token.PUBLIC:
 484                         case Token.SEALED:
 485                         case Token.STATIC:
 486                         case Token.STRUCT:
 487                                 return InputKind.CompilationUnit;
 488
 489                         // Definitely expression
 490                         case Token.FIXED:
 491                         case Token.BOOL:
 492                         case Token.BYTE:
 493                         case Token.CHAR:
 494                         case Token.DECIMAL:
 495                         case Token.DOUBLE:
 496                         case Token.FLOAT:
 497                         case Token.INT:
 498                         case Token.LONG:
 499                         case Token.NEW:
 500                         case Token.OBJECT:
 501                         case Token.SBYTE:
 502                         case Token.SHORT:
 503                         case Token.STRING:
 504                         case Token.UINT:
 505                         case Token.ULONG:
 506                                 return InputKind.StatementOrExpression;
 507
 508                         // These need deambiguation help
 509                         case Token.USING:
 510                                 t = tokenizer.token ();
 511                                 if (t == Token.EOF)
 512                                         return InputKind.EOF;
 513
 514                                 if (t == Token.IDENTIFIER)
 515                                         return InputKind.CompilationUnit;
 516                                 return InputKind.StatementOrExpression;
 517
 518
 519                         // Distinguish between:
 520                         //    delegate opt_anonymous_method_signature block
 521                         //    delegate type
 522                         case Token.DELEGATE:
 523                                 t = tokenizer.token ();
 524                                 if (t == Token.EOF)
 525                                         return InputKind.EOF;
 526                                 if (t == Token.OPEN_PARENS || t == Token.OPEN_BRACE)
 527                                         return InputKind.StatementOrExpression;
 528                                 return InputKind.CompilationUnit;
 529
 530                         // Distinguih between:
 531                         //    unsafe block
 532                         //    unsafe as modifier of a type declaration
 533                         case Token.UNSAFE:
 534                                 t = tokenizer.token ();
 535                                 if (t == Token.EOF)
 536                                         return InputKind.EOF;
 537                                 if (t == Token.OPEN_PARENS)
 538                                         return InputKind.StatementOrExpression;
 539                                 return InputKind.CompilationUnit;
 540
 541                         // These are errors: we list explicitly what we had
 542                         // from the grammar, ERROR and then everything else
 543
 544                         case Token.READONLY:
 545                         case Token.OVERRIDE:
 546                         case Token.ERROR:
 547                                 return InputKind.Error;
 548
 549                         // This catches everything else allowed by
 550                         // expressions.  We could add one-by-one use cases
 551                         // if needed.
 552                         default:
 553                                 return InputKind.StatementOrExpression;
 554                         }
 555                 }
 556
 557                 //
 558                 // Parses the string @input and returns a CSharpParser if succeeful.
 559                 //
 560                 // if @silent is set to true then no errors are
 561                 // reported to the user.  This is used to do various calls to the
 562                 // parser and check if the expression is parsable.
 563                 //
 564                 // @partial_input: if @silent is true, then it returns whether the
 565                 // parsed expression was partial, and more data is needed
 566                 //
 567                 CSharpParser ParseString (ParseMode mode, string input, out bool partial_input)
 568                 {
 569                         partial_input = false;
 570                         Reset ();
 571
 572                         var enc = ctx.Settings.Encoding;
 573                         var s = new MemoryStream (enc.GetBytes (input));
 574                         SeekableStreamReader seekable = new SeekableStreamReader (s, enc);
 575
 576                         InputKind kind = ToplevelOrStatement (seekable);
 577                         if (kind == InputKind.Error){
 578                                 if (mode == ParseMode.ReportErrors)
 579                                         ctx.Report.Error (-25, "Detection Parsing Error");
 580                                 partial_input = false;
 581                                 return null;
 582                         }
 583
 584                         if (kind == InputKind.EOF){
 585                                 if (mode == ParseMode.ReportErrors)
 586                                         Console.Error.WriteLine ("Internal error: EOF condition should have been detected in a previous call with silent=true");
 587                                 partial_input = true;
 588                                 return null;
 589
 590                         }
 591                         seekable.Position = 0;
 592
 593                         source_file.DeclarationFound = false;
 594                         CSharpParser parser = new CSharpParser (seekable, source_file, new ParserSession ());
 595
 596                         if (kind == InputKind.StatementOrExpression){
 597                                 parser.Lexer.putback_char = Tokenizer.EvalStatementParserCharacter;
 598                                 parser.Lexer.parsing_block++;
 599                                 ctx.Settings.StatementMode = true;
 600                         } else {
 601                                 parser.Lexer.putback_char = Tokenizer.EvalCompilationUnitParserCharacter;
 602                                 ctx.Settings.StatementMode = false;
 603                         }
 604
 605                         if (mode == ParseMode.GetCompletions)
 606                                 parser.Lexer.CompleteOnEOF = true;
 607
 608                         ReportPrinter old_printer = null;
 609                         if ((mode == ParseMode.Silent || mode == ParseMode.GetCompletions))
 610                                 old_printer = ctx.Report.SetPrinter (new StreamReportPrinter (TextWriter.Null));
 611
 612                         try {
 613                                 parser.parse ();
 614                         } finally {
 615                                 if (ctx.Report.Errors != 0){
 616                                         if (mode != ParseMode.ReportErrors  && parser.UnexpectedEOF)
 617                                                 partial_input = true;
 618
 619                                         if (parser.undo != null)
 620                                                 parser.undo.ExecuteUndo ();
 621
 622                                         parser = null;
 623                                 }
 624
 625                                 if (old_printer != null)
 626                                         ctx.Report.SetPrinter (old_printer);
 627                         }
 628                         return parser;
 629                 }
 630
 631                 CompiledMethod CompileBlock (Class host, Undo undo, Report Report)
 632                 {
 633 #if STATIC
 634                         throw new NotSupportedException ();
 635 #else
 636                         string current_debug_name = "eval-" + count + ".dll";
 637                         ++count;
 638
 639                         AssemblyDefinitionDynamic assembly;
 640                         AssemblyBuilderAccess access;
 641
 642                         if (Environment.GetEnvironmentVariable ("SAVE") != null) {
 643                                 access = AssemblyBuilderAccess.RunAndSave;
 644                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name, current_debug_name);
 645                                 assembly.Importer = importer;
 646                         } else {
 647 #if NET_4_0
 648                                 access = AssemblyBuilderAccess.RunAndCollect;
 649 #else
 650                                 access = AssemblyBuilderAccess.Run;
 651 #endif
 652                                 assembly = new AssemblyDefinitionDynamic (module, current_debug_name);
 653                         }
 654
 655                         assembly.Create (AppDomain.CurrentDomain, access);
 656
 657                         Method expression_method;
 658                         if (host != null) {
 659                                 var base_class_imported = importer.ImportType (base_class);
 660                                 var baseclass_list = new List<FullNamedExpression> (1) {
 661                                         new TypeExpression (base_class_imported, host.Location)
 662                                 };
 663
 664                                 host.SetBaseTypes (baseclass_list);
 665
 666                                 expression_method = (Method) host.Members[0];
 667
 668                                 if ((expression_method.ModFlags & Modifiers.ASYNC) != 0) {
 669                                         //
 670                                         // Host method is async. When WaitOnTask is set we wrap it with wait
 671                                         //
 672                                         // void AsyncWait (ref object $retval) {
 673                                         //      $retval = Host();
 674                                         //      ((Task)$retval).Wait();  // When WaitOnTask is set
 675                                         // }
 676                                         //
 677                                         var p = new ParametersCompiled (
 678                                                 new Parameter (new TypeExpression (module.Compiler.BuiltinTypes.Object, Location.Null), "$retval", Parameter.Modifier.REF, null, Location.Null)
 679                                         );
 680
 681                                         var method = new Method(host, new TypeExpression(module.Compiler.BuiltinTypes.Void, Location.Null),
 682                                                 Modifiers.PUBLIC | Modifiers.STATIC, new MemberName("AsyncWait"), p, null);
 683
 684                                         method.Block = new ToplevelBlock(method.Compiler, p, Location.Null);
 685                                         method.Block.AddStatement(new StatementExpression (new SimpleAssign(
 686                                                 new SimpleName(p [0].Name, Location.Null),
 687                                                 new Invocation(new SimpleName(expression_method.MemberName.Name, Location.Null), new Arguments(0)),
 688                                                 Location.Null), Location.Null));
 689
 690                                         if (WaitOnTask) {
 691                                                 var task = new Cast (expression_method.TypeExpression, new SimpleName (p [0].Name, Location.Null), Location.Null);
 692
 693                                                 method.Block.AddStatement (new StatementExpression (new Invocation (
 694                                                                 new MemberAccess (task, "Wait", Location.Null),
 695                                                         new Arguments (0)), Location.Null));
 696                                         }
 697
 698                                         host.AddMember(method);
 699
 700                                         expression_method = method;
 701                                 }
 702
 703                                 host.CreateContainer();
 704                                 host.DefineContainer();
 705                                 host.Define();
 706
 707                         } else {
 708                                 expression_method = null;
 709                         }
 710
 711                         module.CreateContainer ();
 712
 713                         // Disable module and source file re-definition checks
 714                         module.EnableRedefinition ();
 715                         source_file.EnableRedefinition ();
 716
 717                         module.Define ();
 718
 719                         if (Report.Errors != 0){
 720                                 if (undo != null)
 721                                         undo.ExecuteUndo ();
 722
 723                                 return null;
 724                         }
 725
 726                         if (host != null){
 727                                 host.PrepareEmit ();
 728                                 host.EmitContainer ();
 729                         }
 730
 731                         module.EmitContainer ();
 732                         if (Report.Errors != 0){
 733                                 if (undo != null)
 734                                         undo.ExecuteUndo ();
 735                                 return null;
 736                         }
 737
 738                         module.CloseContainer ();
 739                         if (host != null)
 740                                 host.CloseContainer ();
 741
 742                         if (access == AssemblyBuilderAccess.RunAndSave)
 743                                 assembly.Save ();
 744
 745                         if (host == null)
 746                                 return null;
 747
 748                         //
 749                         // Unlike Mono, .NET requires that the MethodInfo is fetched, it cant
 750                         // work from MethodBuilders.   Retarded, I know.
 751                         //
 752                         var tt = assembly.Builder.GetType (host.TypeBuilder.Name);
 753                         var mi = tt.GetMethod (expression_method.MemberName.Name);
 754
 755                         //
 756                         // We need to then go from FieldBuilder to FieldInfo
 757                         // or reflection gets confused (it basically gets confused, and variables override each
 758                         // other).
 759                         //
 760                         foreach (var member in host.Members) {
 761                                 var field = member as Field;
 762                                 if (field == null)
 763                                         continue;
 764
 765                                 var fi = tt.GetField (field.Name);
 766
 767                                 Tuple<FieldSpec, FieldInfo> old;
 768
 769                                 // If a previous value was set, nullify it, so that we do
 770                                 // not leak memory
 771                                 if (fields.TryGetValue (field.Name, out old)) {
 772                                         if (old.Item1.MemberType.IsStruct) {
 773                                                 //
 774                                                 // TODO: Clear fields for structs
 775                                                 //
 776                                         } else {
 777                                                 try {
 778                                                         old.Item2.SetValue (null, null);
 779                                                 } catch {
 780                                                 }
 781                                         }
 782                                 }
 783
 784                                 fields[field.Name] = Tuple.Create (field.Spec, fi);
 785                         }
 786
 787                         return (CompiledMethod) System.Delegate.CreateDelegate (typeof (CompiledMethod), mi);
 788 #endif
 789                 }
 790
 791                 /// <summary>
 792                 ///   A sentinel value used to indicate that no value was
 793                 ///   was set by the compiled function.   This is used to
 794                 ///   differentiate between a function not returning a
 795                 ///   value and null.
 796                 /// </summary>
 797                 internal static class QuitValue { }
 798
 799                 internal Tuple<FieldSpec, FieldInfo> LookupField (string name)
 800                 {
 801                         Tuple<FieldSpec, FieldInfo> fi;
 802                         fields.TryGetValue (name, out fi);
 803                         return fi;
 804                 }
 805
 806                 static string Quote (string s)
 807                 {
 808                         if (s.IndexOf ('"') != -1)
 809                                 s = s.Replace ("\"", "\\\"");
 810
 811                         return "\"" + s + "\"";
 812                 }
 813
 814                 public string GetUsing ()
 815                 {
 816                         StringBuilder sb = new StringBuilder ();
 817                         // TODO:
 818                         //foreach (object x in ns.using_alias_list)
 819                         //    sb.AppendFormat ("using {0};\n", x);
 820
 821                         foreach (var ue in source_file.Usings) {
 822                                 sb.AppendFormat ("using {0};", ue.ToString ());
 823                                 sb.Append (Environment.NewLine);
 824                         }
 825
 826                         return sb.ToString ();
 827                 }
 828
 829                 internal List<string> GetUsingList ()
 830                 {
 831                         var res = new List<string> ();
 832
 833                         foreach (var ue in source_file.Usings) {
 834                                 if (ue.Alias != null || ue.ResolvedExpression == null)
 835                                         continue;
 836
 837                                 res.Add (ue.NamespaceExpression.Name);
 838                         }
 839
 840                         return res;
 841                 }
 842
 843                 internal string [] GetVarNames ()
 844                 {
 845                         lock (evaluator_lock){
 846                                 return new List<string> (fields.Keys).ToArray ();
 847                         }
 848                 }
 849
 850                 public string GetVars ()
 851                 {
 852                         lock (evaluator_lock){
 853                                 StringBuilder sb = new StringBuilder ();
 854
 855                                 foreach (var de in fields){
 856                                         var fi = LookupField (de.Key);
 857                                         object value;
 858                                         try {
 859                                                 value = fi.Item2.GetValue (null);
 860                                                 if (value is string)
 861                                                         value = Quote ((string)value);
 862                                         } catch {
 863                                                 value = "<error reading value>";
 864                                         }
 865
 866                                         sb.AppendFormat ("{0} {1} = {2}", fi.Item1.MemberType.GetSignatureForError (), de.Key, value);
 867                                         sb.AppendLine ();
 868                                 }
 869
 870                                 return sb.ToString ();
 871                         }
 872                 }
 873
 874                 /// <summary>
 875                 ///    Loads the given assembly and exposes the API to the user.
 876                 /// </summary>
 877                 public void LoadAssembly (string file)
 878                 {
 879                         var loader = new DynamicLoader (importer, ctx);
 880                         var assembly = loader.LoadAssemblyFile (file, false);
 881                         if (assembly == null)
 882                                 return;
 883
 884                         lock (evaluator_lock){
 885                                 importer.ImportAssembly (assembly, module.GlobalRootNamespace);
 886                         }
 887                 }
 888
 889                 /// <summary>
 890                 ///    Exposes the API of the given assembly to the Evaluator
 891                 /// </summary>
 892                 public void ReferenceAssembly (Assembly a)
 893                 {
 894                         lock (evaluator_lock){
 895                                 importer.ImportAssembly (a, module.GlobalRootNamespace);
 896                         }
 897                 }
 898         }
 899
 900
 901         /// <summary>
 902         ///   A delegate that can be used to invoke the
 903         ///   compiled expression or statement.
 904         /// </summary>
 905         /// <remarks>
 906         ///   Since the Compile methods will compile
 907         ///   statements and expressions into the same
 908         ///   delegate, you can tell if a value was returned
 909         ///   by checking whether the returned value is of type
 910         ///   NoValueSet.
 911         /// </remarks>
 912
 913         public delegate void CompiledMethod (ref object retvalue);
 914
 915         /// <summary>
 916         ///   The default base class for every interaction line
 917         /// </summary>
 918         /// <remarks>
 919         ///   The expressions and statements behave as if they were
 920         ///   a static method of this class.   The InteractiveBase class
 921         ///   contains a number of useful methods, but can be overwritten
 922         ///   by setting the InteractiveBaseType property in the Evaluator
 923         /// </remarks>
 924         public class InteractiveBase {
 925                 /// <summary>
 926                 ///   Determines where the standard output of methods in this class will go.
 927                 /// </summary>
 928                 public static TextWriter Output = Console.Out;
 929
 930                 /// <summary>
 931                 ///   Determines where the standard error of methods in this class will go.
 932                 /// </summary>
 933                 public static TextWriter Error = Console.Error;
 934
 935                 /// <summary>
 936                 ///   The primary prompt used for interactive use.
 937                 /// </summary>
 938                 public static string Prompt             = "csharp> ";
 939
 940                 /// <summary>
 941                 ///   The secondary prompt used for interactive use (used when
 942                 ///   an expression is incomplete).
 943                 /// </summary>
 944                 public static string ContinuationPrompt = "      > ";
 945
 946                 /// <summary>
 947                 ///   Used to signal that the user has invoked the  `quit' statement.
 948                 /// </summary>
 949                 public static bool QuitRequested;
 950
 951                 public static Evaluator Evaluator;
 952
 953                 /// <summary>
 954                 ///   Shows all the variables defined so far.
 955                 /// </summary>
 956                 static public void ShowVars ()
 957                 {
 958                         Output.Write (Evaluator.GetVars ());
 959                         Output.Flush ();
 960                 }
 961
 962                 /// <summary>
 963                 ///   Displays the using statements in effect at this point.
 964                 /// </summary>
 965                 static public void ShowUsing ()
 966                 {
 967                         Output.Write (Evaluator.GetUsing ());
 968                         Output.Flush ();
 969                 }
 970
 971                 /// <summary>
 972                 ///   Times the execution of the given delegate
 973                 /// </summary>
 974                 static public TimeSpan Time (Action a)
 975                 {
 976                         DateTime start = DateTime.Now;
 977                         a ();
 978                         return DateTime.Now - start;
 979                 }
 980
 981                 /// <summary>
 982                 ///   Loads the assemblies from a package
 983                 /// </summary>
 984                 /// <remarks>
 985                 ///   Loads the assemblies from a package.   This is equivalent
 986                 ///   to passing the -pkg: command line flag to the C# compiler
 987                 ///   on the command line.
 988                 /// </remarks>
 989                 static public void LoadPackage (string pkg)
 990                 {
 991                         if (pkg == null){
 992                                 Error.WriteLine ("Invalid package specified");
 993                                 return;
 994                         }
 995
 996                         string pkgout = Driver.GetPackageFlags (pkg, null);
 997
 998                         string [] xargs = pkgout.Trim (new Char [] {' ', '\n', '\r', '\t'}).
 999                                 Split (new Char [] { ' ', '\t'});
1000
1001                         foreach (string s in xargs){
1002                                 if (s.StartsWith ("-r:") || s.StartsWith ("/r:") || s.StartsWith ("/reference:")){
1003                                         string lib = s.Substring (s.IndexOf (':')+1);
1004
1005                                         Evaluator.LoadAssembly (lib);
1006                                         continue;
1007                                 }
1008                         }
1009                 }
1010
1011                 /// <summary>
1012                 ///   Loads the assembly
1013                 /// </summary>
1014                 /// <remarks>
1015                 ///   Loads the specified assembly and makes its types
1016                 ///   available to the evaluator.  This is equivalent
1017                 ///   to passing the -pkg: command line flag to the C#
1018                 ///   compiler on the command line.
1019                 /// </remarks>
1020                 static public void LoadAssembly (string assembly)
1021                 {
1022                         Evaluator.LoadAssembly (assembly);
1023                 }
1024
1025                 static public void print (object obj)
1026                 {
1027                         Output.WriteLine (obj);
1028                 }
1029
1030                 static public void print (string fmt, params object [] args)
1031                 {
1032                         Output.WriteLine (fmt, args);
1033                 }
1034
1035                 /// <summary>
1036                 ///   Returns a list of available static methods.
1037                 /// </summary>
1038                 static public string help {
1039                         get {
1040                                 return "Static methods:\n" +
1041 #if !NET_2_1
1042                                         "  Describe (object);       - Describes the object's type\n" +
1043 #endif
1044                                         "  LoadPackage (package);   - Loads the given Package (like -pkg:FILE)\n" +
1045                                         "  LoadAssembly (assembly); - Loads the given assembly (like -r:ASSEMBLY)\n" +
1046                                         "  ShowVars ();             - Shows defined local variables.\n" +
1047                                         "  ShowUsing ();            - Show active using declarations.\n" +
1048                                         "  Prompt                   - The prompt used by the C# shell\n" +
1049                                         "  ContinuationPrompt       - The prompt for partial input\n" +
1050                                         "  Time (() => { });        - Times the specified code\n" +
1051                                         "  print (obj);             - Shorthand for Console.WriteLine\n" +
1052                                         "  quit;                    - You'll never believe it - this quits the repl!\n" +
1053                                         "  help;                    - This help text\n";
1054                         }
1055                 }
1056
1057                 /// <summary>
1058                 ///   Indicates to the read-eval-print-loop that the interaction should be finished.
1059                 /// </summary>
1060                 static public object quit {
1061                         get {
1062                                 QuitRequested = true;
1063
1064                                 // To avoid print null at the exit
1065                                 return typeof (Evaluator.QuitValue);
1066                         }
1067                 }
1068
1069                 /// <summary>
1070                 ///   Same as quit - useful in script scenerios
1071                 /// </summary>
1072                 static public void Quit () {
1073                         QuitRequested = true;
1074                 }
1075
1076 #if !NET_2_1
1077                 /// <summary>
1078                 ///   Describes an object or a type.
1079                 /// </summary>
1080                 /// <remarks>
1081                 ///   This method will show a textual representation
1082                 ///   of the object's type.  If the object is a
1083                 ///   System.Type it renders the type directly,
1084                 ///   otherwise it renders the type returned by
1085                 ///   invoking GetType on the object.
1086                 /// </remarks>
1087                 static public string Describe (object x)
1088                 {
1089                         if (x == null)
1090                                 return "<null>";
1091
1092                         var type = x as Type ?? x.GetType ();
1093
1094                         StringWriter sw = new StringWriter ();
1095                         new Outline (type, sw, true, false, false).OutlineType ();
1096                         return sw.ToString ();
1097                 }
1098 #endif
1099         }
1100
1101         class InteractiveMethod : Method
1102         {
1103                 public InteractiveMethod(TypeDefinition parent, FullNamedExpression returnType, Modifiers mod, ParametersCompiled parameters)
1104                         : base(parent, returnType, mod, new MemberName("Host"), parameters, null)
1105                 {
1106                 }
1107
1108                 public void ChangeToAsync ()
1109                 {
1110                         ModFlags |= Modifiers.ASYNC;
1111                         ModFlags &= ~Modifiers.UNSAFE;
1112                         type_expr = new TypeExpression(Module.PredefinedTypes.Task.TypeSpec, Location);
1113                         parameters = ParametersCompiled.EmptyReadOnlyParameters;
1114                 }
1115
1116                 public override string GetSignatureForError()
1117                 {
1118                         return "InteractiveHost";
1119                 }
1120         }
1121
1122         class HoistedEvaluatorVariable : HoistedVariable
1123         {
1124                 public HoistedEvaluatorVariable (Field field)
1125                         : base (null, field)
1126                 {
1127                 }
1128
1129                 protected override FieldExpr GetFieldExpression (EmitContext ec)
1130                 {
1131                         return new FieldExpr (field, field.Location);
1132                 }
1133         }
1134
1135         /// <summary>
1136         ///    A class used to assign values if the source expression is not void
1137         ///
1138         ///    Used by the interactive shell to allow it to call this code to set
1139         ///    the return value for an invocation.
1140         /// </summary>
1141         class OptionalAssign : SimpleAssign {
1142                 public OptionalAssign (Expression s, Location loc)
1143                         : base (null, s, loc)
1144                 {
1145                 }
1146
1147                 public override Location StartLocation {
1148                         get {
1149                                 return Location.Null;
1150                         }
1151                 }
1152
1153                 protected override Expression DoResolve (ResolveContext ec)
1154                 {
1155                         Expression clone = source.Clone (new CloneContext ());
1156
1157                         clone = clone.Resolve (ec);
1158                         if (clone == null)
1159                                 return null;
1160
1161                         //
1162                         // A useful feature for the REPL: if we can resolve the expression
1163                         // as a type, Describe the type;
1164                         //
1165                         if (ec.Module.Evaluator.DescribeTypeExpressions && !(ec.CurrentAnonymousMethod is AsyncInitializer)) {
1166                                 var old_printer = ec.Report.SetPrinter (new SessionReportPrinter ());
1167                                 Expression tclone;
1168                                 try {
1169                                         // Note: clone context cannot be shared otherwise block mapping would leak
1170                                         tclone = source.Clone (new CloneContext ());
1171                                         tclone = tclone.Resolve (ec, ResolveFlags.Type);
1172                                         if (ec.Report.Errors > 0)
1173                                                 tclone = null;
1174                                 } finally {
1175                                         ec.Report.SetPrinter (old_printer);
1176                                 }
1177
1178                                 if (tclone is TypeExpr) {
1179                                         Arguments args = new Arguments (1);
1180                                         args.Add (new Argument (new TypeOf ((TypeExpr) clone, Location)));
1181                                         return new Invocation (new SimpleName ("Describe", Location), args).Resolve (ec);
1182                                 }
1183                         }
1184
1185                         // This means its really a statement.
1186                         if (clone.Type.Kind == MemberKind.Void || clone is DynamicInvocation || clone is Assign) {
1187                                 return clone;
1188                         }
1189
1190                         source = clone;
1191
1192                         var host = (Method) ec.MemberContext.CurrentMemberDefinition;
1193
1194                         if (host.ParameterInfo.IsEmpty) {
1195                                 eclass = ExprClass.Value;
1196                                 type = InternalType.FakeInternalType;
1197                                 return this;
1198                         }
1199
1200                         target = new SimpleName (host.ParameterInfo[0].Name, Location);
1201
1202                         return base.DoResolve (ec);
1203                 }
1204
1205                 public override void EmitStatement(EmitContext ec)
1206                 {
1207                         if (target == null) {
1208                                 source.Emit (ec);
1209                                 return;
1210                         }
1211
1212                         base.EmitStatement(ec);
1213                 }
1214         }
1215
1216         public class Undo
1217         {
1218                 List<Action> undo_actions;
1219
1220                 public void AddTypeContainer (TypeContainer current_container, TypeDefinition tc)
1221                 {
1222                         if (current_container == tc){
1223                                 Console.Error.WriteLine ("Internal error: inserting container into itself");
1224                                 return;
1225                         }
1226
1227                         if (undo_actions == null)
1228                                 undo_actions = new List<Action> ();
1229
1230                         var existing = current_container.Containers.FirstOrDefault (l => l.Basename == tc.Basename);
1231                         if (existing != null) {
1232                                 current_container.RemoveContainer (existing);
1233                                 undo_actions.Add (() => current_container.AddTypeContainer (existing));
1234                         }
1235
1236                         undo_actions.Add (() => current_container.RemoveContainer (tc));
1237                 }
1238
1239                 public void ExecuteUndo ()
1240                 {
1241                         if (undo_actions == null)
1242                                 return;
1243
1244                         foreach (var p in undo_actions){
1245                                 p ();
1246                         }
1247
1248                         undo_actions = null;
1249                 }
1250         }
1251
1252 }