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