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[mcs.git] / mcs / iterators.cs
blob9c7920899ccd3b7d7a9682b36928b830c587bac4
1 //
2 // iterators.cs: Support for implementing iterators
3 //
4 // Author:
5 // Miguel de Icaza (miguel@ximian.com)
6 // Marek Safar (marek.safar@gmail.com)
7 //
8 // Dual licensed under the terms of the MIT X11 or GNU GPL
9 // Copyright 2003 Ximian, Inc.
10 // Copyright 2003-2008 Novell, Inc.
11 //
12
13 // TODO:
14 // Flow analysis for Yield.
15 //
16
17 using System;
18 using System.Collections;
19 using System.Reflection;
20 using System.Reflection.Emit;
21
22 namespace Mono.CSharp {
23
24 public class Yield : ResumableStatement {
25 Expression expr;
26 bool unwind_protect;
27
28 int resume_pc;
29
30 public Yield (Expression expr, Location l)
31 {
32 this.expr = expr;
33 loc = l;
34 }
35
36 public static bool CheckContext (EmitContext ec, Location loc)
37 {
38 for (Block block = ec.CurrentBlock; block != null; block = block.Parent) {
39 if (!block.Unsafe)
40 continue;
41
42 Report.Error (1629, loc, "Unsafe code may not appear in iterators");
43 return false;
44 }
45
46 //
47 // We can't use `ec.InUnsafe' here because it's allowed to have an iterator
48 // inside an unsafe class. See test-martin-29.cs for an example.
49 //
50 if (!ec.CurrentAnonymousMethod.IsIterator) {
51 Report.Error (1621, loc,
52 "The yield statement cannot be used inside " +
53 "anonymous method blocks");
54 return false;
55 }
56
57 return true;
58 }
59
60 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
61 {
62 expr.MutateHoistedGenericType (storey);
63 }
64
65 public override bool Resolve (EmitContext ec)
66 {
67 expr = expr.Resolve (ec);
68 if (expr == null)
69 return false;
70
71 Report.Debug (64, "RESOLVE YIELD #1", this, ec, expr, expr.GetType (),
72 ec.CurrentAnonymousMethod, ec.CurrentIterator);
73
74 if (!CheckContext (ec, loc))
75 return false;
76
77 Iterator iterator = ec.CurrentIterator;
78 if (expr.Type != iterator.OriginalIteratorType) {
79 expr = Convert.ImplicitConversionRequired (
80 ec, expr, iterator.OriginalIteratorType, loc);
81 if (expr == null)
82 return false;
83 }
84
85 if (!ec.CurrentBranching.CurrentUsageVector.IsUnreachable)
86 unwind_protect = ec.CurrentBranching.AddResumePoint (this, loc, out resume_pc);
87
88 return true;
89 }
90
91 protected override void DoEmit (EmitContext ec)
92 {
93 ec.CurrentIterator.MarkYield (ec, expr, resume_pc, unwind_protect, resume_point);
94 }
95
96 protected override void CloneTo (CloneContext clonectx, Statement t)
97 {
98 Yield target = (Yield) t;
99
100 target.expr = expr.Clone (clonectx);
101 }
102 }
103
104 public class YieldBreak : ExitStatement {
105 public YieldBreak (Location l)
106 {
107 loc = l;
108 }
109
110 public override void Error_FinallyClause ()
111 {
112 Report.Error (1625, loc, "Cannot yield in the body of a finally clause");
113 }
114
115 protected override void CloneTo (CloneContext clonectx, Statement target)
116 {
117 throw new NotSupportedException ();
118 }
119
120 protected override bool DoResolve (EmitContext ec)
121 {
122 return Yield.CheckContext (ec, loc);
123 }
124
125 protected override void DoEmit (EmitContext ec)
126 {
127 ec.CurrentIterator.EmitYieldBreak (ec.ig, unwind_protect);
128 }
129
130 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
131 {
132 // nothing to do
133 }
134 }
135
136 //
137 // Wraps method block into iterator wrapper block
138 //
139 class IteratorStatement : Statement
140 {
141 Iterator iterator;
142 ExplicitBlock original_block;
143
144 public IteratorStatement (Iterator iterator, ExplicitBlock original_block)
145 {
146 this.iterator = iterator;
147 this.original_block = original_block;
148 this.loc = iterator.Location;
149 }
150
151 protected override void CloneTo (CloneContext clonectx, Statement target)
152 {
153 IteratorStatement t = (IteratorStatement) target;
154 t.original_block = (ExplicitBlock) original_block.Clone (clonectx);
155 t.iterator = (Iterator) iterator.Clone (clonectx);
156 }
157
158 public override bool Resolve (EmitContext ec)
159 {
160 ec.StartFlowBranching (iterator);
161 bool ok = original_block.Resolve (ec);
162 ec.EndFlowBranching ();
163 return ok;
164 }
165
166 protected override void DoEmit (EmitContext ec)
167 {
168 iterator.EmitMoveNext (ec, original_block);
169 }
170
171 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
172 {
173 original_block.MutateHoistedGenericType (storey);
174 iterator.MutateHoistedGenericType (storey);
175 }
176 }
177
178 public class IteratorStorey : AnonymousMethodStorey
179 {
180 class IteratorMethod : Method
181 {
182 readonly IteratorStorey host;
183
184 public IteratorMethod (IteratorStorey host, FullNamedExpression returnType, int mod, MemberName name)
185 : base (host, null, returnType, mod | Modifiers.DEBUGGER_HIDDEN | Modifiers.COMPILER_GENERATED,
186 name, Parameters.EmptyReadOnlyParameters, null)
187 {
188 this.host = host;
189
190 Block = new ToplevelBlock (host.Iterator.Container.Toplevel, null, Location);
191 }
192
193 public override EmitContext CreateEmitContext (DeclSpace tc, ILGenerator ig)
194 {
195 EmitContext ec = new EmitContext (
196 this, tc, this.ds, Location, ig, MemberType, ModFlags, false);
197
198 ec.CurrentAnonymousMethod = host.Iterator;
199 return ec;
200 }
201 }
202
203 class GetEnumeratorMethod : IteratorMethod
204 {
205 sealed class GetEnumeratorStatement : Statement
206 {
207 IteratorStorey host;
208 Expression type;
209
210 Expression new_storey;
211
212 public GetEnumeratorStatement (IteratorStorey host, Expression type)
213 {
214 this.host = host;
215 this.type = type;
216 loc = host.Location;
217 }
218
219 protected override void CloneTo (CloneContext clonectx, Statement target)
220 {
221 throw new NotSupportedException ();
222 }
223
224 public override bool Resolve (EmitContext ec)
225 {
226 type = type.ResolveAsTypeTerminal (ec, false);
227 if ((type == null) || (type.Type == null))
228 return false;
229
230 TypeExpression storey_type_expr = new TypeExpression (host.TypeBuilder, loc);
231 ArrayList init = null;
232 if (host.hoisted_this != null) {
233 init = new ArrayList (host.hoisted_params == null ? 1 : host.HoistedParameters.Count + 1);
234 HoistedThis ht = host.hoisted_this;
235 FieldExpr from = new FieldExpr (ht.Field.FieldBuilder, loc);
236 from.InstanceExpression = CompilerGeneratedThis.Instance;
237 init.Add (new ElementInitializer (ht.Field.Name, from, loc));
238 }
239
240 if (host.hoisted_params != null) {
241 if (init == null)
242 init = new ArrayList (host.HoistedParameters.Count);
243
244 for (int i = 0; i < host.hoisted_params.Count; ++i) {
245 HoistedParameter hp = (HoistedParameter) host.hoisted_params [i];
246 HoistedParameter hp_cp = (HoistedParameter) host.hoisted_params_copy [i];
247
248 FieldExpr from = new FieldExpr (hp_cp.Field.FieldBuilder, loc);
249 from.InstanceExpression = CompilerGeneratedThis.Instance;
250
251 init.Add (new ElementInitializer (hp.Field.Name, from, loc));
252 }
253 }
254
255 if (init != null) {
256 new_storey = new NewInitialize (storey_type_expr, new ArrayList (0),
257 new CollectionOrObjectInitializers (init, loc), loc);
258 } else {
259 new_storey = new New (storey_type_expr, new ArrayList (0), loc);
260 }
261
262 new_storey = new_storey.Resolve (ec);
263 if (new_storey != null)
264 new_storey = Convert.ImplicitConversionRequired (ec, new_storey, type.Type, loc);
265
266 if (TypeManager.int_interlocked_compare_exchange == null) {
267 Type t = TypeManager.CoreLookupType ("System.Threading", "Interlocked", Kind.Class, true);
268 if (t != null) {
269 TypeManager.int_interlocked_compare_exchange = TypeManager.GetPredefinedMethod (
270 t, "CompareExchange", loc, TypeManager.int32_type,
271 TypeManager.int32_type, TypeManager.int32_type);
272 }
273 }
274
275 ec.CurrentBranching.CurrentUsageVector.Goto ();
276 return true;
277 }
278
279 protected override void DoEmit (EmitContext ec)
280 {
281 ILGenerator ig = ec.ig;
282 Label label_init = ig.DefineLabel ();
283
284 ig.Emit (OpCodes.Ldarg_0);
285 ig.Emit (OpCodes.Ldflda, host.PC.FieldBuilder);
286 IntConstant.EmitInt (ig, (int) Iterator.State.Start);
287 IntConstant.EmitInt (ig, (int) Iterator.State.Uninitialized);
288 ig.Emit (OpCodes.Call, TypeManager.int_interlocked_compare_exchange);
289
290 IntConstant.EmitInt (ig, (int) Iterator.State.Uninitialized);
291 ig.Emit (OpCodes.Bne_Un_S, label_init);
292
293 ig.Emit (OpCodes.Ldarg_0);
294 ig.Emit (OpCodes.Ret);
295
296 ig.MarkLabel (label_init);
297
298 new_storey.Emit (ec);
299 ig.Emit (OpCodes.Ret);
300 }
301
302 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
303 {
304 throw new NotSupportedException ();
305 }
306 }
307
308 public GetEnumeratorMethod (IteratorStorey host, FullNamedExpression returnType, MemberName name)
309 : base (host, returnType, 0, name)
310 {
311 Block.AddStatement (new GetEnumeratorStatement (host, type_name));
312 }
313 }
314
315 class DisposeMethod : IteratorMethod
316 {
317 sealed class DisposeMethodStatement : Statement
318 {
319 Iterator iterator;
320
321 public DisposeMethodStatement (Iterator iterator)
322 {
323 this.iterator = iterator;
324 this.loc = iterator.Location;
325 }
326
327 protected override void CloneTo (CloneContext clonectx, Statement target)
328 {
329 throw new NotSupportedException ();
330 }
331
332 public override bool Resolve (EmitContext ec)
333 {
334 return true;
335 }
336
337 protected override void DoEmit (EmitContext ec)
338 {
339 iterator.EmitDispose (ec);
340 }
341
342 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
343 {
344 throw new NotSupportedException ();
345 }
346 }
347
348 public DisposeMethod (IteratorStorey host)
349 : base (host, TypeManager.system_void_expr, Modifiers.PUBLIC, new MemberName ("Dispose", host.Location))
350 {
351 host.AddMethod (this);
352
353 Block = new ToplevelBlock (host.Iterator.Container, null, Location);
354 Block.AddStatement (new DisposeMethodStatement (host.Iterator));
355 }
356 }
357
358 //
359 // Uses Method as method info
360 //
361 class DynamicMethodGroupExpr : MethodGroupExpr
362 {
363 readonly Method method;
364
365 public DynamicMethodGroupExpr (Method method, Location loc)
366 : base (null, loc)
367 {
368 this.method = method;
369 }
370
371 public override Expression DoResolve (EmitContext ec)
372 {
373 Methods = new MethodBase [] { method.MethodBuilder };
374 type = method.Parent.TypeBuilder;
375 InstanceExpression = new CompilerGeneratedThis (type, Location);
376 return base.DoResolve (ec);
377 }
378 }
379
380 public readonly Iterator Iterator;
381
382 TypeExpr iterator_type_expr;
383 Field pc_field;
384 Field current_field;
385
386 TypeExpr enumerator_type;
387 TypeExpr enumerable_type;
388 #if GMCS_SOURCE
389 TypeArguments generic_args;
390 TypeExpr generic_enumerator_type;
391 TypeExpr generic_enumerable_type;
392 #else
393 const TypeArguments generic_args = null;
394 #endif
395
396 ArrayList hoisted_params_copy;
397 int local_name_idx;
398
399 public IteratorStorey (Iterator iterator)
400 : base (iterator.Container.Toplevel, iterator.Host,
401 iterator.OriginalMethod as MemberBase, iterator.GenericMethod, "Iterator")
402 {
403 this.Iterator = iterator;
404 HasHoistedVariables = true;
405 }
406
407 public Field PC {
408 get { return pc_field; }
409 }
410
411 public Field CurrentField {
412 get { return current_field; }
413 }
414
415 public ArrayList HoistedParameters {
416 get { return hoisted_params; }
417 }
418
419 protected override TypeExpr [] ResolveBaseTypes (out TypeExpr base_class)
420 {
421 iterator_type_expr = new TypeExpression (MutateType (Iterator.OriginalIteratorType), Location);
422
423 #if GMCS_SOURCE
424 generic_args = new TypeArguments (Location);
425 generic_args.Add (iterator_type_expr);
426 #endif
427
428 ArrayList list = new ArrayList ();
429 if (Iterator.IsEnumerable) {
430 enumerable_type = new TypeExpression (
431 TypeManager.ienumerable_type, Location);
432 list.Add (enumerable_type);
433
434 #if GMCS_SOURCE
435 generic_enumerable_type = new ConstructedType (
436 TypeManager.generic_ienumerable_type,
437 generic_args, Location);
438 list.Add (generic_enumerable_type);
439 #endif
440 }
441
442 enumerator_type = new TypeExpression (
443 TypeManager.ienumerator_type, Location);
444 list.Add (enumerator_type);
445
446 list.Add (new TypeExpression (TypeManager.idisposable_type, Location));
447
448 #if GMCS_SOURCE
449 generic_enumerator_type = new ConstructedType (
450 TypeManager.generic_ienumerator_type,
451 generic_args, Location);
452 list.Add (generic_enumerator_type);
453 #endif
454
455 type_bases = list;
456
457 return base.ResolveBaseTypes (out base_class);
458 }
459
460 protected override string GetVariableMangledName (LocalInfo local_info)
461 {
462 return "<" + local_info.Name + ">__" + local_name_idx++.ToString ();
463 }
464
465 public void DefineIteratorMembers ()
466 {
467 pc_field = AddCompilerGeneratedField ("$PC", TypeManager.system_int32_expr);
468 current_field = AddCompilerGeneratedField ("$current", iterator_type_expr);
469
470 if (hoisted_params != null) {
471 //
472 // Iterators are independent, each GetEnumerator call has to
473 // create same enumerator therefore we have to keep original values
474 // around for re-initialization
475 //
476 // TODO: Do it for assigned/modified parameters only
477 //
478 hoisted_params_copy = new ArrayList (hoisted_params.Count);
479 foreach (HoistedParameter hp in hoisted_params) {
480 hoisted_params_copy.Add (new HoistedParameter (hp, "<$>" + hp.Field.Name));
481 }
482 }
483
484 #if GMCS_SOURCE
485 Define_Current (true);
486 #endif
487 Define_Current (false);
488 new DisposeMethod (this);
489 Define_Reset ();
490
491 if (Iterator.IsEnumerable) {
492 MemberName name = new MemberName (
493 new MemberName ("System.Collections.IEnumerable", Location), "GetEnumerator", Location);
494
495 #if GMCS_SOURCE
496 Method get_enumerator = new IteratorMethod (this, enumerator_type, 0, name);
497
498 name = new MemberName (
499 new MemberName ("System.Collections.Generic.IEnumerable", generic_args, Location), "GetEnumerator", Location);
500 Method gget_enumerator = new GetEnumeratorMethod (this, generic_enumerator_type, name);
501
502 //
503 // Just call generic GetEnumerator implementation
504 //
505 get_enumerator.Block.AddStatement (
506 new Return (new Invocation (new DynamicMethodGroupExpr (gget_enumerator, Location), new ArrayList (0)), Location));
507
508 AddMethod (get_enumerator);
509 AddMethod (gget_enumerator);
510 #else
511 AddMethod (new GetEnumeratorMethod (this, enumerator_type, name));
512 #endif
513 }
514 }
515
516 protected override void EmitHoistedParameters (EmitContext ec, ArrayList hoisted)
517 {
518 base.EmitHoistedParameters (ec, hoisted);
519 base.EmitHoistedParameters (ec, hoisted_params_copy);
520 }
521
522 void Define_Current (bool is_generic)
523 {
524 MemberName left;
525 TypeExpr type;
526
527 if (is_generic) {
528 left = new MemberName (
529 "System.Collections.Generic.IEnumerator",
530 generic_args, Location);
531 type = iterator_type_expr;
532 } else {
533 left = new MemberName ("System.Collections.IEnumerator", Location);
534 type = TypeManager.system_object_expr;
535 }
536
537 MemberName name = new MemberName (left, "Current", null, Location);
538
539 ToplevelBlock get_block = new ToplevelBlock (Location);
540 get_block.AddStatement (new CurrentBlock (this, is_generic));
541
542 Accessor getter = new Accessor (get_block, 0, null, null, Location);
543
544 Property current = new Property (
545 this, type, Modifiers.DEBUGGER_HIDDEN, name, null, getter, null, false);
546 AddProperty (current);
547 }
548
549 void Define_Reset ()
550 {
551 Method reset = new Method (
552 this, null, TypeManager.system_void_expr,
553 Modifiers.PUBLIC | Modifiers.DEBUGGER_HIDDEN,
554 new MemberName ("Reset", Location),
555 Parameters.EmptyReadOnlyParameters, null);
556 AddMethod (reset);
557
558 reset.Block = new ToplevelBlock (Location);
559 reset.Block.AddStatement (Create_ThrowNotSupported ());
560 }
561
562 Statement Create_ThrowNotSupported ()
563 {
564 TypeExpr ex_type = new TypeLookupExpression ("System.NotSupportedException");
565
566 return new Throw (new New (ex_type, null, Location), Location);
567 }
568
569 protected class CurrentBlock : Statement {
570 IteratorStorey host;
571 bool is_generic;
572
573 public CurrentBlock (IteratorStorey host, bool is_generic)
574 {
575 this.host = host;
576 this.is_generic = is_generic;
577 loc = host.Location;
578 }
579
580 protected override void CloneTo (CloneContext clonectx, Statement target)
581 {
582 throw new NotSupportedException ();
583 }
584
585 public override bool Resolve (EmitContext ec)
586 {
587 // We emit a 'ret', so prevent the enclosing TopLevelBlock from emitting one too
588 ec.CurrentBranching.CurrentUsageVector.Goto ();
589 return true;
590 }
591
592 protected override void DoEmit (EmitContext ec)
593 {
594 ILGenerator ig = ec.ig;
595
596 ig.Emit (OpCodes.Ldarg_0);
597 ig.Emit (OpCodes.Ldfld, host.CurrentField.FieldBuilder);
598 if (!is_generic)
599 ig.Emit (OpCodes.Box, host.CurrentField.MemberType);
600 ig.Emit (OpCodes.Ret);
601 }
602
603 public override void MutateHoistedGenericType (AnonymousMethodStorey storey)
604 {
605 throw new NotSupportedException ();
606 }
607 }
608 }
609
610 //
611 // Iterators are implemented as hidden anonymous block
612 //
613 public class Iterator : AnonymousExpression {
614 public readonly IMethodData OriginalMethod;
615 AnonymousMethodMethod method;
616 public readonly TypeContainer Host;
617 public readonly bool IsEnumerable;
618
619 //
620 // The state as we generate the iterator
621 //
622 Label move_next_ok, move_next_error;
623 LocalBuilder skip_finally, current_pc;
624
625 public LocalBuilder SkipFinally {
626 get { return skip_finally; }
627 }
628
629 public LocalBuilder CurrentPC {
630 get { return current_pc; }
631 }
632
633 public Block Container {
634 get { return OriginalMethod.Block; }
635 }
636
637 public GenericMethod GenericMethod {
638 get { return OriginalMethod.GenericMethod; }
639 }
640
641 public readonly Type OriginalIteratorType;
642
643 readonly IteratorStorey IteratorHost;
644
645 public enum State {
646 Running = -3, // Used only in CurrentPC, never stored into $PC
647 Uninitialized = -2,
648 After = -1,
649 Start = 0
650 }
651
652 public override void AddStoreyReference (AnonymousMethodStorey storey)
653 {
654 // do nothing
655 }
656
657 public void EmitYieldBreak (ILGenerator ig, bool unwind_protect)
658 {
659 ig.Emit (unwind_protect ? OpCodes.Leave : OpCodes.Br, move_next_error);
660 }
661
662 void EmitMoveNext_NoResumePoints (EmitContext ec, Block original_block)
663 {
664 ILGenerator ig = ec.ig;
665
666 ig.Emit (OpCodes.Ldarg_0);
667 ig.Emit (OpCodes.Ldfld, IteratorHost.PC.FieldBuilder);
668
669 ig.Emit (OpCodes.Ldarg_0);
670 IntConstant.EmitInt (ig, (int) State.After);
671 ig.Emit (OpCodes.Stfld, IteratorHost.PC.FieldBuilder);
672
673 // We only care if the PC is zero (start executing) or non-zero (don't do anything)
674 ig.Emit (OpCodes.Brtrue, move_next_error);
675
676 SymbolWriter.StartIteratorBody (ec.ig);
677 original_block.Emit (ec);
678 SymbolWriter.EndIteratorBody (ec.ig);
679
680 ig.MarkLabel (move_next_error);
681 ig.Emit (OpCodes.Ldc_I4_0);
682 ig.Emit (OpCodes.Ret);
683 }
684
685 internal void EmitMoveNext (EmitContext ec, Block original_block)
686 {
687 ILGenerator ig = ec.ig;
688
689 move_next_ok = ig.DefineLabel ();
690 move_next_error = ig.DefineLabel ();
691
692 if (resume_points == null) {
693 EmitMoveNext_NoResumePoints (ec, original_block);
694 return;
695 }
696
697 current_pc = ec.GetTemporaryLocal (TypeManager.uint32_type);
698 ig.Emit (OpCodes.Ldarg_0);
699 ig.Emit (OpCodes.Ldfld, IteratorHost.PC.FieldBuilder);
700 ig.Emit (OpCodes.Stloc, current_pc);
701
702 // We're actually in state 'running', but this is as good a PC value as any if there's an abnormal exit
703 ig.Emit (OpCodes.Ldarg_0);
704 IntConstant.EmitInt (ig, (int) State.After);
705 ig.Emit (OpCodes.Stfld, IteratorHost.PC.FieldBuilder);
706
707 Label [] labels = new Label [1 + resume_points.Count];
708 labels [0] = ig.DefineLabel ();
709
710 bool need_skip_finally = false;
711 for (int i = 0; i < resume_points.Count; ++i) {
712 ResumableStatement s = (ResumableStatement) resume_points [i];
713 need_skip_finally |= s is ExceptionStatement;
714 labels [i+1] = s.PrepareForEmit (ec);
715 }
716
717 if (need_skip_finally) {
718 skip_finally = ec.GetTemporaryLocal (TypeManager.bool_type);
719 ig.Emit (OpCodes.Ldc_I4_0);
720 ig.Emit (OpCodes.Stloc, skip_finally);
721 }
722
723 SymbolWriter.StartIteratorDispatcher (ec.ig);
724 ig.Emit (OpCodes.Ldloc, current_pc);
725 ig.Emit (OpCodes.Switch, labels);
726
727 ig.Emit (OpCodes.Br, move_next_error);
728 SymbolWriter.EndIteratorDispatcher (ec.ig);
729
730 ig.MarkLabel (labels [0]);
731
732 SymbolWriter.StartIteratorBody (ec.ig);
733 original_block.Emit (ec);
734 SymbolWriter.EndIteratorBody (ec.ig);
735
736 SymbolWriter.StartIteratorDispatcher (ec.ig);
737
738 ig.Emit (OpCodes.Ldarg_0);
739 IntConstant.EmitInt (ig, (int) State.After);
740 ig.Emit (OpCodes.Stfld, IteratorHost.PC.FieldBuilder);
741
742 ig.MarkLabel (move_next_error);
743 ig.Emit (OpCodes.Ldc_I4_0);
744 ig.Emit (OpCodes.Ret);
745
746 ig.MarkLabel (move_next_ok);
747 ig.Emit (OpCodes.Ldc_I4_1);
748 ig.Emit (OpCodes.Ret);
749
750 SymbolWriter.EndIteratorDispatcher (ec.ig);
751 }
752
753 public void EmitDispose (EmitContext ec)
754 {
755 ILGenerator ig = ec.ig;
756
757 Label end = ig.DefineLabel ();
758
759 Label [] labels = null;
760 int n_resume_points = resume_points == null ? 0 : resume_points.Count;
761 for (int i = 0; i < n_resume_points; ++i) {
762 ResumableStatement s = (ResumableStatement) resume_points [i];
763 Label ret = s.PrepareForDispose (ec, end);
764 if (ret.Equals (end) && labels == null)
765 continue;
766 if (labels == null) {
767 labels = new Label [resume_points.Count + 1];
768 for (int j = 0; j <= i; ++j)
769 labels [j] = end;
770 }
771 labels [i+1] = ret;
772 }
773
774 if (labels != null) {
775 current_pc = ec.GetTemporaryLocal (TypeManager.uint32_type);
776 ig.Emit (OpCodes.Ldarg_0);
777 ig.Emit (OpCodes.Ldfld, IteratorHost.PC.FieldBuilder);
778 ig.Emit (OpCodes.Stloc, current_pc);
779 }
780
781 ig.Emit (OpCodes.Ldarg_0);
782 IntConstant.EmitInt (ig, (int) State.After);
783 ig.Emit (OpCodes.Stfld, IteratorHost.PC.FieldBuilder);
784
785 if (labels != null) {
786 //SymbolWriter.StartIteratorDispatcher (ec.ig);
787 ig.Emit (OpCodes.Ldloc, current_pc);
788 ig.Emit (OpCodes.Switch, labels);
789 //SymbolWriter.EndIteratorDispatcher (ec.ig);
790
791 foreach (ResumableStatement s in resume_points)
792 s.EmitForDispose (ec, this, end, true);
793 }
794
795 ig.MarkLabel (end);
796 }
797
798
799 ArrayList resume_points;
800 public int AddResumePoint (ResumableStatement stmt)
801 {
802 if (resume_points == null)
803 resume_points = new ArrayList ();
804 resume_points.Add (stmt);
805 return resume_points.Count;
806 }
807
808 //
809 // Called back from Yield
810 //
811 public void MarkYield (EmitContext ec, Expression expr, int resume_pc, bool unwind_protect, Label resume_point)
812 {
813 ILGenerator ig = ec.ig;
814
815 // Store the new current
816 ig.Emit (OpCodes.Ldarg_0);
817 expr.Emit (ec);
818 ig.Emit (OpCodes.Stfld, IteratorHost.CurrentField.FieldBuilder);
819
820 // store resume program-counter
821 ig.Emit (OpCodes.Ldarg_0);
822 IntConstant.EmitInt (ig, resume_pc);
823 ig.Emit (OpCodes.Stfld, IteratorHost.PC.FieldBuilder);
824
825 // mark finally blocks as disabled
826 if (unwind_protect && skip_finally != null) {
827 ig.Emit (OpCodes.Ldc_I4_1);
828 ig.Emit (OpCodes.Stloc, skip_finally);
829 }
830
831 // Return ok
832 ig.Emit (unwind_protect ? OpCodes.Leave : OpCodes.Br, move_next_ok);
833
834 ig.MarkLabel (resume_point);
835 }
836
837 public override string ContainerType {
838 get { return "iterator"; }
839 }
840
841 public override bool IsIterator {
842 get { return true; }
843 }
844
845 public override AnonymousMethodStorey Storey {
846 get { return IteratorHost; }
847 }
848
849 //
850 // Our constructor
851 //
852 private Iterator (IMethodData method, TypeContainer host, Type iterator_type, bool is_enumerable)
853 : base (
854 new ToplevelBlock (method.Block, Parameters.EmptyReadOnlyParameters, method.Block.StartLocation),
855 TypeManager.bool_type,
856 method.Location)
857 {
858 this.OriginalMethod = method;
859 this.OriginalIteratorType = iterator_type;
860 this.IsEnumerable = is_enumerable;
861 this.Host = host;
862
863 IteratorHost = Block.ChangeToIterator (this, method.Block);
864 }
865
866 public override string GetSignatureForError ()
867 {
868 return OriginalMethod.GetSignatureForError ();
869 }
870
871 public override Expression DoResolve (EmitContext ec)
872 {
873 method = new AnonymousMethodMethod (Storey,
874 this, Storey, null, TypeManager.system_boolean_expr,
875 Modifiers.PUBLIC, OriginalMethod.GetSignatureForError (),
876 new MemberName ("MoveNext", Location),
877 Parameters.EmptyReadOnlyParameters);
878
879 if (!Compatible (ec))
880 return null;
881
882 IteratorHost.DefineIteratorMembers ();
883
884 eclass = ExprClass.Value;
885 type = ec.ReturnType;
886 return this;
887 }
888
889 public override void Emit (EmitContext ec)
890 {
891 //
892 // Load Iterator storey instance
893 //
894 method.Storey.Instance.Emit (ec);
895
896 //
897 // Initialize iterator PC when it's unitialized
898 //
899 if (IsEnumerable) {
900 ILGenerator ig = ec.ig;
901 ig.Emit (OpCodes.Dup);
902 IntConstant.EmitInt (ig, (int)State.Uninitialized);
903
904 FieldInfo field = IteratorHost.PC.FieldBuilder;
905 #if GMCS_SOURCE
906 if (Storey.MemberName.IsGeneric)
907 field = TypeBuilder.GetField (Storey.Instance.Type, field);
908 #endif
909 ig.Emit (OpCodes.Stfld, field);
910 }
911 }
912
913 public override Expression CreateExpressionTree (EmitContext ec)
914 {
915 throw new NotSupportedException ("ET");
916 }
917
918 public static void CreateIterator (IMethodData method, TypeContainer parent, int modifiers)
919 {
920 bool is_enumerable;
921 Type iterator_type;
922
923 Type ret = method.ReturnType;
924 if (ret == null)
925 return;
926
927 if (!CheckType (ret, out iterator_type, out is_enumerable)) {
928 Report.Error (1624, method.Location,
929 "The body of `{0}' cannot be an iterator block " +
930 "because `{1}' is not an iterator interface type",
931 method.GetSignatureForError (),
932 TypeManager.CSharpName (ret));
933 return;
934 }
935
936 Parameters parameters = method.ParameterInfo;
937 for (int i = 0; i < parameters.Count; i++) {
938 Parameter p = parameters [i];
939 Parameter.Modifier mod = p.ModFlags;
940 if ((mod & Parameter.Modifier.ISBYREF) != 0) {
941 Report.Error (1623, p.Location,
942 "Iterators cannot have ref or out parameters");
943 return;
944 }
945
946 if ((mod & Parameter.Modifier.ARGLIST) != 0) {
947 Report.Error (1636, method.Location,
948 "__arglist is not allowed in parameter list of iterators");
949 return;
950 }
951
952 if (parameters.Types [i].IsPointer) {
953 Report.Error (1637, p.Location,
954 "Iterators cannot have unsafe parameters or " +
955 "yield types");
956 return;
957 }
958 }
959
960 if ((modifiers & Modifiers.UNSAFE) != 0) {
961 Report.Error (1629, method.Location, "Unsafe code may not appear in iterators");
962 return;
963 }
964
965 Iterator iter = new Iterator (method, parent, iterator_type, is_enumerable);
966 iter.Storey.DefineType ();
967 }
968
969 static bool CheckType (Type ret, out Type original_iterator_type, out bool is_enumerable)
970 {
971 original_iterator_type = null;
972 is_enumerable = false;
973
974 if (ret == TypeManager.ienumerable_type) {
975 original_iterator_type = TypeManager.object_type;
976 is_enumerable = true;
977 return true;
978 }
979 if (ret == TypeManager.ienumerator_type) {
980 original_iterator_type = TypeManager.object_type;
981 is_enumerable = false;
982 return true;
983 }
984
985 if (!TypeManager.IsGenericType (ret))
986 return false;
987
988 Type[] args = TypeManager.GetTypeArguments (ret);
989 if (args.Length != 1)
990 return false;
991
992 Type gt = TypeManager.DropGenericTypeArguments (ret);
993 if (gt == TypeManager.generic_ienumerable_type) {
994 original_iterator_type = args [0];
995 is_enumerable = true;
996 return true;
997 }
998
999 if (gt == TypeManager.generic_ienumerator_type) {
1000 original_iterator_type = args [0];
1001 is_enumerable = false;
1002 return true;
1003 }
1004
1005 return false;
1006 }
1007 }
1008 }
1009
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