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