2 // flowanalyis.cs: The control flow analysis code
5 // Martin Baulig (martin@ximian.com)
7 // (C) 2001, 2002, 2003 Ximian, Inc.
12 using System.Collections;
13 using System.Reflection;
14 using System.Reflection.Emit;
15 using System.Diagnostics;
20 // A new instance of this class is created every time a new block is resolved
21 // and if there's branching in the block's control flow.
23 public abstract class FlowBranching
26 // The type of a FlowBranching.
28 public enum BranchingType : byte {
29 // Normal (conditional or toplevel) block.
49 // The type of one sibling of a branching.
51 public enum SiblingType : byte {
61 // This is used in the control flow analysis code to specify whether the
62 // current code block may return to its enclosing block before reaching
65 public enum FlowReturns : byte {
68 // It can never return.
71 // This means that the block contains a conditional return statement
75 // The code always returns, ie. there's an unconditional return / break
80 public sealed class Reachability
82 FlowReturns returns, breaks, throws, barrier;
84 public FlowReturns Returns {
85 get { return returns; }
87 public FlowReturns Breaks {
88 get { return breaks; }
90 public FlowReturns Throws {
91 get { return throws; }
93 public FlowReturns Barrier {
94 get { return barrier; }
96 public Reachability (FlowReturns returns, FlowReturns breaks,
97 FlowReturns throws, FlowReturns barrier)
99 this.returns = returns;
100 this.breaks = breaks;
101 this.throws = throws;
102 this.barrier = barrier;
105 public Reachability Clone ()
107 return new Reachability (returns, breaks, throws, barrier);
111 // Performs an `And' operation on the FlowReturns status
112 // (for instance, a block only returns Always if all its siblings
115 public static FlowReturns AndFlowReturns (FlowReturns a, FlowReturns b)
117 if (a == FlowReturns.Undefined)
121 case FlowReturns.Never:
122 if (b == FlowReturns.Never)
123 return FlowReturns.Never;
125 return FlowReturns.Sometimes;
127 case FlowReturns.Sometimes:
128 return FlowReturns.Sometimes;
130 case FlowReturns.Always:
131 if (b == FlowReturns.Always)
132 return FlowReturns.Always;
134 return FlowReturns.Sometimes;
137 throw new ArgumentException ();
141 public static FlowReturns OrFlowReturns (FlowReturns a, FlowReturns b)
143 if (a == FlowReturns.Undefined)
147 case FlowReturns.Never:
150 case FlowReturns.Sometimes:
151 if (b == FlowReturns.Always)
152 return FlowReturns.Always;
154 return FlowReturns.Sometimes;
156 case FlowReturns.Always:
157 return FlowReturns.Always;
160 throw new ArgumentException ();
164 public static void And (ref Reachability a, Reachability b, bool do_break)
172 // `break' does not "break" in a Switch or a LoopBlock
174 bool a_breaks = do_break && a.AlwaysBreaks;
175 bool b_breaks = do_break && b.AlwaysBreaks;
177 bool a_has_barrier, b_has_barrier;
180 // This is the normal case: the code following a barrier
181 // cannot be reached.
183 a_has_barrier = a.AlwaysHasBarrier;
184 b_has_barrier = b.AlwaysHasBarrier;
187 // Special case for Switch and LoopBlocks: we can reach the
188 // code after the barrier via the `break'.
190 a_has_barrier = !a.AlwaysBreaks && a.AlwaysHasBarrier;
191 b_has_barrier = !b.AlwaysBreaks && b.AlwaysHasBarrier;
194 bool a_unreachable = a_breaks || a.AlwaysThrows || a_has_barrier;
195 bool b_unreachable = b_breaks || b.AlwaysThrows || b_has_barrier;
198 // Do all code paths always return ?
200 if (a.AlwaysReturns) {
201 if (b.AlwaysReturns || b_unreachable)
202 a.returns = FlowReturns.Always;
204 a.returns = FlowReturns.Sometimes;
205 } else if (b.AlwaysReturns) {
206 if (a.AlwaysReturns || a_unreachable)
207 a.returns = FlowReturns.Always;
209 a.returns = FlowReturns.Sometimes;
210 } else if (!a.MayReturn) {
212 a.returns = FlowReturns.Sometimes;
214 a.returns = FlowReturns.Never;
215 } else if (!b.MayReturn) {
217 a.returns = FlowReturns.Sometimes;
219 a.returns = FlowReturns.Never;
222 a.breaks = AndFlowReturns (a.breaks, b.breaks);
223 a.throws = AndFlowReturns (a.throws, b.throws);
224 a.barrier = AndFlowReturns (a.barrier, b.barrier);
226 if (a_unreachable && b_unreachable)
227 a.barrier = FlowReturns.Always;
228 else if (a_unreachable || b_unreachable)
229 a.barrier = FlowReturns.Sometimes;
231 a.barrier = FlowReturns.Never;
234 public void Or (Reachability b)
236 returns = OrFlowReturns (returns, b.returns);
237 breaks = OrFlowReturns (breaks, b.breaks);
238 throws = OrFlowReturns (throws, b.throws);
239 barrier = OrFlowReturns (barrier, b.barrier);
242 public static Reachability Never ()
244 return new Reachability (
245 FlowReturns.Never, FlowReturns.Never,
246 FlowReturns.Never, FlowReturns.Never);
249 public FlowReturns Reachable {
251 if ((returns == FlowReturns.Always) ||
252 (breaks == FlowReturns.Always) ||
253 (throws == FlowReturns.Always) ||
254 (barrier == FlowReturns.Always))
255 return FlowReturns.Never;
256 else if ((returns == FlowReturns.Never) &&
257 (breaks == FlowReturns.Never) &&
258 (throws == FlowReturns.Never) &&
259 (barrier == FlowReturns.Never))
260 return FlowReturns.Always;
262 return FlowReturns.Sometimes;
266 public bool AlwaysBreaks {
267 get { return breaks == FlowReturns.Always; }
270 public bool MayBreak {
271 get { return breaks != FlowReturns.Never; }
274 public bool AlwaysReturns {
275 get { return returns == FlowReturns.Always; }
278 public bool MayReturn {
279 get { return returns != FlowReturns.Never; }
282 public bool AlwaysThrows {
283 get { return throws == FlowReturns.Always; }
286 public bool MayThrow {
287 get { return throws != FlowReturns.Never; }
290 public bool AlwaysHasBarrier {
291 get { return barrier == FlowReturns.Always; }
294 public bool MayHaveBarrier {
295 get { return barrier != FlowReturns.Never; }
298 public bool IsUnreachable {
299 get { return Reachable == FlowReturns.Never; }
302 public void SetReturns ()
304 returns = FlowReturns.Always;
307 public void SetReturnsSometimes ()
309 returns = FlowReturns.Sometimes;
312 public void SetBreaks ()
314 breaks = FlowReturns.Always;
317 public void ResetBreaks ()
319 breaks = FlowReturns.Never;
322 public void SetThrows ()
324 throws = FlowReturns.Always;
327 public void SetThrowsSometimes ()
329 throws = FlowReturns.Sometimes;
332 public void SetBarrier ()
334 barrier = FlowReturns.Always;
337 public void ResetBarrier ()
339 barrier = FlowReturns.Never;
342 static string ShortName (FlowReturns returns)
345 case FlowReturns.Never:
347 case FlowReturns.Sometimes:
354 public override string ToString ()
356 return String.Format ("[{0}:{1}:{2}:{3}:{4}]",
357 ShortName (returns), ShortName (breaks),
358 ShortName (throws), ShortName (barrier),
359 ShortName (Reachable));
363 public static FlowBranching CreateBranching (FlowBranching parent, BranchingType type, Block block, Location loc)
366 case BranchingType.Exception:
367 throw new InvalidOperationException ();
369 case BranchingType.Switch:
370 return new FlowBranchingBlock (parent, type, SiblingType.SwitchSection, block, loc);
372 case BranchingType.SwitchSection:
373 return new FlowBranchingBlock (parent, type, SiblingType.Block, block, loc);
375 case BranchingType.Block:
376 return new FlowBranchingBlock (parent, type, SiblingType.Block, block, loc);
378 case BranchingType.Loop:
379 return new FlowBranchingLoop (parent, block, loc);
382 return new FlowBranchingBlock (parent, type, SiblingType.Conditional, block, loc);
387 // The type of this flow branching.
389 public readonly BranchingType Type;
392 // The block this branching is contained in. This may be null if it's not
393 // a top-level block and it doesn't declare any local variables.
395 public readonly Block Block;
398 // The parent of this branching or null if this is the top-block.
400 public readonly FlowBranching Parent;
403 // Start-Location of this flow branching.
405 public readonly Location Location;
408 // If this is an infinite loop.
410 public bool Infinite;
415 VariableMap param_map, local_map;
417 static int next_id = 0;
421 // The vector contains a BitArray with information about which local variables
422 // and parameters are already initialized at the current code position.
424 public class UsageVector {
426 // The type of this branching.
428 public readonly SiblingType Type;
431 // Start location of this branching.
433 public readonly Location Location;
436 // This is only valid for SwitchSection, Try, Catch and Finally.
438 public readonly Block Block;
441 // If this is true, then the usage vector has been modified and must be
442 // merged when we're done with this branching.
447 // The number of parameters in this block.
449 public readonly int CountParameters;
452 // The number of locals in this block.
454 public readonly int CountLocals;
457 // If not null, then we inherit our state from this vector and do a
458 // copy-on-write. If null, then we're the first sibling in a top-level
459 // block and inherit from the empty vector.
461 public readonly UsageVector InheritsFrom;
464 // This is used to construct a list of UsageVector's.
466 public UsageVector Next;
471 MyBitVector locals, parameters;
472 Reachability reachability;
474 static int next_id = 0;
478 // Normally, you should not use any of these constructors.
480 public UsageVector (SiblingType type, UsageVector parent,
481 Block block, Location loc,
482 int num_params, int num_locals)
487 this.InheritsFrom = parent;
488 this.CountParameters = num_params;
489 this.CountLocals = num_locals;
491 if (parent != null) {
493 locals = new MyBitVector (parent.locals, CountLocals);
496 parameters = new MyBitVector (parent.parameters, num_params);
498 reachability = parent.Reachability.Clone ();
501 locals = new MyBitVector (null, CountLocals);
504 parameters = new MyBitVector (null, num_params);
506 reachability = Reachability.Never ();
512 public UsageVector (SiblingType type, UsageVector parent,
513 Block block, Location loc)
514 : this (type, parent, block, loc,
515 parent.CountParameters, parent.CountLocals)
518 public UsageVector (MyBitVector parameters, MyBitVector locals,
519 Reachability reachability, Block block,
522 this.Type = SiblingType.Block;
526 this.reachability = reachability;
527 this.parameters = parameters;
528 this.locals = locals;
534 // This does a deep copy of the usage vector.
536 public UsageVector Clone ()
538 UsageVector retval = new UsageVector (
539 Type, null, Block, Location,
540 CountParameters, CountLocals);
542 if (retval.locals != null)
543 retval.locals = locals.Clone ();
545 if (parameters != null)
546 retval.parameters = parameters.Clone ();
548 retval.reachability = reachability.Clone ();
553 public bool IsAssigned (VariableInfo var)
555 if (!var.IsParameter && Reachability.IsUnreachable)
558 return var.IsAssigned (var.IsParameter ? parameters : locals);
561 public void SetAssigned (VariableInfo var)
563 if (!var.IsParameter && Reachability.IsUnreachable)
567 var.SetAssigned (var.IsParameter ? parameters : locals);
570 public bool IsFieldAssigned (VariableInfo var, string name)
572 if (!var.IsParameter && Reachability.IsUnreachable)
575 return var.IsFieldAssigned (var.IsParameter ? parameters : locals, name);
578 public void SetFieldAssigned (VariableInfo var, string name)
580 if (!var.IsParameter && Reachability.IsUnreachable)
584 var.SetFieldAssigned (var.IsParameter ? parameters : locals, name);
587 public Reachability Reachability {
593 public void Return ()
595 if (!reachability.IsUnreachable) {
597 reachability.SetReturns ();
603 if (!reachability.IsUnreachable) {
605 reachability.SetBreaks ();
611 if (!reachability.IsUnreachable) {
613 reachability.SetThrows ();
619 if (!reachability.IsUnreachable) {
621 reachability.SetBarrier ();
626 // Merges a child branching.
628 public UsageVector MergeChild (FlowBranching branching)
630 UsageVector result = branching.Merge ();
632 Report.Debug (2, " MERGING CHILD", this, branching, IsDirty,
633 result.ParameterVector, result.LocalVector,
634 result.Reachability, reachability, Type);
636 Reachability new_r = result.Reachability;
638 if (branching.Type == BranchingType.Loop) {
639 bool may_leave_loop = new_r.MayBreak;
640 new_r.ResetBreaks ();
642 if (branching.Infinite && !may_leave_loop) {
643 if (new_r.Returns == FlowReturns.Sometimes) {
644 // If we're an infinite loop and do not break,
645 // the code after the loop can never be reached.
646 // However, if we may return from the loop,
647 // then we do always return (or stay in the
654 if (new_r.Returns == FlowReturns.Always) {
655 // We're either finite or we may leave the loop.
656 new_r.SetReturnsSometimes ();
658 if (new_r.Throws == FlowReturns.Always) {
659 // We're either finite or we may leave the loop.
660 new_r.SetThrowsSometimes ();
663 if (!new_r.MayReturn && !new_r.MayThrow)
664 new_r.ResetBarrier ();
666 } else if (branching.Type == BranchingType.Switch) {
667 if (new_r.MayBreak || new_r.MayReturn)
668 new_r.ResetBarrier ();
670 new_r.ResetBreaks ();
674 // We've now either reached the point after the branching or we will
675 // never get there since we always return or always throw an exception.
677 // If we can reach the point after the branching, mark all locals and
678 // parameters as initialized which have been initialized in all branches
679 // we need to look at (see above).
682 if ((Type == SiblingType.SwitchSection) && !new_r.IsUnreachable) {
683 Report.Error (163, Location,
684 "Control cannot fall through from one " +
685 "case label to another");
689 if (locals != null && result.LocalVector != null)
690 locals.Or (result.LocalVector);
692 if (result.ParameterVector != null)
693 parameters.Or (result.ParameterVector);
695 if ((branching.Type == BranchingType.Block) && branching.Block.Implicit)
696 reachability = new_r.Clone ();
698 reachability.Or (new_r);
700 Report.Debug (2, " MERGING CHILD DONE", this, result,
701 new_r, reachability);
708 protected void MergeFinally (FlowBranching branching, UsageVector f_origins,
709 MyBitVector f_params)
711 for (UsageVector vector = f_origins; vector != null; vector = vector.Next) {
712 MyBitVector temp_params = f_params.Clone ();
713 temp_params.Or (vector.Parameters);
717 public void MergeFinally (FlowBranching branching, UsageVector f_vector,
718 UsageVector f_origins)
720 if (parameters != null) {
721 if (f_vector != null) {
722 MergeFinally (branching, f_origins, f_vector.Parameters);
723 MyBitVector.Or (ref parameters, f_vector.ParameterVector);
725 MergeFinally (branching, f_origins, parameters);
728 if (f_vector != null && f_vector.LocalVector != null)
729 MyBitVector.Or (ref locals, f_vector.LocalVector);
733 // Tells control flow analysis that the current code position may be reached with
734 // a forward jump from any of the origins listed in `origin_vectors' which is a
735 // list of UsageVectors.
737 // This is used when resolving forward gotos - in the following example, the
738 // variable `a' is uninitialized in line 8 becase this line may be reached via
739 // the goto in line 4:
749 // 8 Console.WriteLine (a);
752 public void MergeJumpOrigins (UsageVector o_vectors)
754 Report.Debug (1, " MERGING JUMP ORIGINS", this);
756 reachability = Reachability.Never ();
758 if (o_vectors == null) {
759 reachability.SetBarrier ();
765 for (UsageVector vector = o_vectors; vector != null;
766 vector = vector.Next) {
767 Report.Debug (1, " MERGING JUMP ORIGIN", vector);
770 if (locals != null && vector.Locals != null)
771 locals.Or (vector.locals);
773 if (parameters != null)
774 parameters.Or (vector.parameters);
777 if (locals != null && vector.Locals != null)
778 locals.And (vector.locals);
779 if (parameters != null)
780 parameters.And (vector.parameters);
783 Reachability.And (ref reachability, vector.Reachability, true);
786 Report.Debug (1, " MERGING JUMP ORIGINS DONE", this);
790 // This is used at the beginning of a finally block if there were
791 // any return statements in the try block or one of the catch blocks.
793 public void MergeFinallyOrigins (UsageVector f_origins)
795 Report.Debug (1, " MERGING FINALLY ORIGIN", this);
797 reachability = Reachability.Never ();
799 for (UsageVector vector = f_origins; vector != null; vector = vector.Next) {
800 Report.Debug (1, " MERGING FINALLY ORIGIN", vector);
802 if (parameters != null)
803 parameters.And (vector.parameters);
805 Reachability.And (ref reachability, vector.Reachability, true);
808 Report.Debug (1, " MERGING FINALLY ORIGIN DONE", this);
811 public void MergeBreakOrigins (UsageVector o_vectors)
813 Report.Debug (1, " MERGING BREAK ORIGINS", this);
815 if (o_vectors == null)
820 for (UsageVector vector = o_vectors; vector != null;
821 vector = vector.Next) {
822 Report.Debug (1, " MERGING BREAK ORIGIN", vector);
825 if (locals != null && vector.Locals != null)
826 locals.Or (vector.locals);
828 if (parameters != null)
829 parameters.Or (vector.parameters);
832 if (locals != null && vector.Locals != null)
833 locals.And (vector.locals);
834 if (parameters != null)
835 parameters.And (vector.parameters);
839 Report.Debug (1, " MERGING BREAK ORIGINS DONE", this);
842 public void CheckOutParameters (FlowBranching branching)
844 if (parameters != null)
845 branching.CheckOutParameters (parameters, branching.Location);
849 // Performs an `or' operation on the locals and the parameters.
851 public void Or (UsageVector new_vector)
854 locals.Or (new_vector.locals);
855 if (parameters != null)
856 parameters.Or (new_vector.parameters);
860 // Performs an `and' operation on the locals.
862 public void AndLocals (UsageVector new_vector)
865 locals.And (new_vector.locals);
868 public bool HasParameters {
870 return parameters != null;
874 public bool HasLocals {
876 return locals != null;
881 // Returns a deep copy of the parameters.
883 public MyBitVector Parameters {
885 if (parameters != null)
886 return parameters.Clone ();
893 // Returns a deep copy of the locals.
895 public MyBitVector Locals {
898 return locals.Clone ();
904 public MyBitVector ParameterVector {
910 public MyBitVector LocalVector {
920 public override string ToString ()
922 StringBuilder sb = new StringBuilder ();
924 sb.Append ("Vector (");
931 sb.Append (reachability);
932 if (parameters != null) {
934 sb.Append (parameters);
940 return sb.ToString ();
945 // Creates a new flow branching which is contained in `parent'.
946 // You should only pass non-null for the `block' argument if this block
947 // introduces any new variables - in this case, we need to create a new
948 // usage vector with a different size than our parent's one.
950 protected FlowBranching (FlowBranching parent, BranchingType type, SiblingType stype,
951 Block block, Location loc)
961 param_map = Block.ParameterMap;
962 local_map = Block.LocalMap;
964 UsageVector parent_vector = parent != null ? parent.CurrentUsageVector : null;
965 vector = new UsageVector (
966 stype, parent_vector, Block, loc,
967 param_map.Length, local_map.Length);
969 param_map = Parent.param_map;
970 local_map = Parent.local_map;
971 vector = new UsageVector (
972 stype, Parent.CurrentUsageVector, null, loc);
978 public abstract UsageVector CurrentUsageVector {
983 // Creates a sibling of the current usage vector.
985 public virtual void CreateSibling (Block block, SiblingType type)
987 UsageVector vector = new UsageVector (
988 type, Parent.CurrentUsageVector, block, Location);
991 Report.Debug (1, " CREATED SIBLING", CurrentUsageVector);
994 public void CreateSibling ()
996 CreateSibling (null, SiblingType.Conditional);
999 protected abstract void AddSibling (UsageVector uv);
1001 public virtual LabeledStatement LookupLabel (string name, Location loc)
1004 return Parent.LookupLabel (name, loc);
1008 "No such label `" + name + "' in this scope");
1012 public abstract void Label (UsageVector origin_vectors);
1015 // Check whether all `out' parameters have been assigned.
1017 public void CheckOutParameters (MyBitVector parameters, Location loc)
1019 for (int i = 0; i < param_map.Count; i++) {
1020 VariableInfo var = param_map [i];
1025 if (var.IsAssigned (parameters))
1028 Report.Error (177, loc, "The out parameter `" +
1029 var.Name + "' must be " +
1030 "assigned before control leaves the current method.");
1034 protected UsageVector Merge (UsageVector sibling_list)
1036 if (sibling_list.Next == null)
1037 return sibling_list;
1039 MyBitVector locals = null;
1040 MyBitVector parameters = null;
1042 Reachability reachability = null;
1044 Report.Debug (2, " MERGING SIBLINGS", this, Name);
1046 for (UsageVector child = sibling_list; child != null; child = child.Next) {
1047 bool do_break = (Type != BranchingType.Switch) &&
1048 (Type != BranchingType.Loop);
1050 Report.Debug (2, " MERGING SIBLING ", child,
1051 child.ParameterVector, child.LocalVector,
1052 reachability, child.Reachability, do_break);
1054 Reachability.And (ref reachability, child.Reachability, do_break);
1056 // A local variable is initialized after a flow branching if it
1057 // has been initialized in all its branches which do neither
1058 // always return or always throw an exception.
1060 // If a branch may return, but does not always return, then we
1061 // can treat it like a never-returning branch here: control will
1062 // only reach the code position after the branching if we did not
1065 // It's important to distinguish between always and sometimes
1066 // returning branches here:
1069 // 2 if (something) {
1073 // 6 Console.WriteLine (a);
1075 // The if block in lines 3-4 always returns, so we must not look
1076 // at the initialization of `a' in line 4 - thus it'll still be
1077 // uninitialized in line 6.
1079 // On the other hand, the following is allowed:
1086 // 6 Console.WriteLine (a);
1088 // Here, `a' is initialized in line 3 and we must not look at
1089 // line 5 since it always returns.
1091 bool do_break_2 = (child.Type != SiblingType.Block) &&
1092 (child.Type != SiblingType.SwitchSection);
1093 bool always_throws = (child.Type != SiblingType.Try) &&
1094 child.Reachability.AlwaysThrows;
1095 bool unreachable = always_throws ||
1096 (do_break_2 && child.Reachability.AlwaysBreaks) ||
1097 child.Reachability.AlwaysReturns ||
1098 child.Reachability.AlwaysHasBarrier;
1100 Report.Debug (2, " MERGING SIBLING #1", reachability,
1101 Type, child.Type, child.Reachability.IsUnreachable,
1102 do_break_2, always_throws, unreachable);
1104 if (!unreachable && (child.LocalVector != null))
1105 MyBitVector.And (ref locals, child.LocalVector);
1107 // An `out' parameter must be assigned in all branches which do
1108 // not always throw an exception.
1109 if ((child.ParameterVector != null) && !child.Reachability.AlwaysThrows)
1110 MyBitVector.And (ref parameters, child.ParameterVector);
1112 Report.Debug (2, " MERGING SIBLING #2", parameters, locals);
1115 if (reachability == null)
1116 reachability = Reachability.Never ();
1118 Report.Debug (2, " MERGING SIBLINGS DONE", parameters, locals,
1119 reachability, Infinite);
1121 return new UsageVector (
1122 parameters, locals, reachability, null, Location);
1125 protected abstract UsageVector Merge ();
1128 // Merge a child branching.
1130 public UsageVector MergeChild (FlowBranching child)
1132 return CurrentUsageVector.MergeChild (child);
1136 // Does the toplevel merging.
1138 public Reachability MergeTopBlock ()
1140 if ((Type != BranchingType.Block) || (Block == null))
1141 throw new NotSupportedException ();
1143 UsageVector vector = new UsageVector (
1144 SiblingType.Block, null, Block, Location,
1145 param_map.Length, local_map.Length);
1147 UsageVector result = vector.MergeChild (this);
1149 Report.Debug (4, "MERGE TOP BLOCK", Location, vector, result.Reachability);
1151 if ((vector.Reachability.Throws != FlowReturns.Always) &&
1152 (vector.Reachability.Barrier != FlowReturns.Always))
1153 CheckOutParameters (vector.Parameters, Location);
1155 return result.Reachability;
1159 // Checks whether we're in a `try' block.
1161 public virtual bool InTryOrCatch (bool is_return)
1163 if ((Block != null) && Block.IsDestructor)
1165 else if (!is_return &&
1166 ((Type == BranchingType.Loop) || (Type == BranchingType.Switch)))
1168 else if (Parent != null)
1169 return Parent.InTryOrCatch (is_return);
1175 // Checks whether we're in a `catch' block.
1177 public virtual bool InCatch ()
1180 return Parent.InCatch ();
1186 // Checks whether we're in a `finally' block.
1188 public virtual bool InFinally (bool is_return)
1191 ((Type == BranchingType.Loop) || (Type == BranchingType.Switch)))
1193 else if (Parent != null)
1194 return Parent.InFinally (is_return);
1199 public virtual bool InLoop ()
1201 if (Type == BranchingType.Loop)
1203 else if (Parent != null)
1204 return Parent.InLoop ();
1209 public virtual bool InSwitch ()
1211 if (Type == BranchingType.Switch)
1213 else if (Parent != null)
1214 return Parent.InSwitch ();
1219 public virtual bool BreakCrossesTryCatchBoundary ()
1221 if ((Type == BranchingType.Loop) || (Type == BranchingType.Switch))
1223 else if (Parent != null)
1224 return Parent.BreakCrossesTryCatchBoundary ();
1229 public virtual void AddFinallyVector (UsageVector vector)
1232 Parent.AddFinallyVector (vector);
1233 else if ((Block == null) || !Block.IsDestructor)
1234 throw new NotSupportedException ();
1237 public virtual void AddBreakVector (UsageVector vector)
1240 Parent.AddBreakVector (vector);
1241 else if ((Block == null) || !Block.IsDestructor)
1242 throw new NotSupportedException ();
1245 public virtual void StealFinallyClauses (ref ArrayList list)
1248 Parent.StealFinallyClauses (ref list);
1251 public bool IsAssigned (VariableInfo vi)
1253 return CurrentUsageVector.IsAssigned (vi);
1256 public bool IsFieldAssigned (VariableInfo vi, string field_name)
1258 if (CurrentUsageVector.IsAssigned (vi))
1261 return CurrentUsageVector.IsFieldAssigned (vi, field_name);
1264 public void SetAssigned (VariableInfo vi)
1266 CurrentUsageVector.SetAssigned (vi);
1269 public void SetFieldAssigned (VariableInfo vi, string name)
1271 CurrentUsageVector.SetFieldAssigned (vi, name);
1274 public override string ToString ()
1276 StringBuilder sb = new StringBuilder ();
1277 sb.Append (GetType ());
1283 if (Block != null) {
1285 sb.Append (Block.ID);
1287 sb.Append (Block.StartLocation);
1290 // sb.Append (Siblings.Length);
1291 // sb.Append (" - ");
1292 sb.Append (CurrentUsageVector);
1294 return sb.ToString ();
1297 public string Name {
1299 return String.Format ("{0} ({1}:{2}:{3})",
1300 GetType (), id, Type, Location);
1305 public class FlowBranchingBlock : FlowBranching
1307 UsageVector sibling_list = null;
1309 public FlowBranchingBlock (FlowBranching parent, BranchingType type,
1310 SiblingType stype, Block block, Location loc)
1311 : base (parent, type, stype, block, loc)
1314 public override UsageVector CurrentUsageVector {
1315 get { return sibling_list; }
1318 protected override void AddSibling (UsageVector sibling)
1320 sibling.Next = sibling_list;
1321 sibling_list = sibling;
1324 public override LabeledStatement LookupLabel (string name, Location loc)
1327 return base.LookupLabel (name, loc);
1329 LabeledStatement s = Block.LookupLabel (name);
1333 return base.LookupLabel (name, loc);
1336 public override void Label (UsageVector origin_vectors)
1338 if (!CurrentUsageVector.Reachability.IsUnreachable) {
1339 UsageVector vector = CurrentUsageVector.Clone ();
1340 vector.Next = origin_vectors;
1341 origin_vectors = vector;
1344 CurrentUsageVector.MergeJumpOrigins (origin_vectors);
1347 protected override UsageVector Merge ()
1349 return Merge (sibling_list);
1353 public class FlowBranchingLoop : FlowBranchingBlock
1355 UsageVector break_origins;
1357 public FlowBranchingLoop (FlowBranching parent, Block block, Location loc)
1358 : base (parent, BranchingType.Loop, SiblingType.Conditional, block, loc)
1361 public override void AddBreakVector (UsageVector vector)
1363 vector = vector.Clone ();
1364 vector.Next = break_origins;
1365 break_origins = vector;
1368 protected override UsageVector Merge ()
1370 UsageVector vector = base.Merge ();
1372 vector.MergeBreakOrigins (break_origins);
1378 public class FlowBranchingException : FlowBranching
1380 ExceptionStatement stmt;
1381 UsageVector current_vector;
1382 UsageVector catch_vectors;
1383 UsageVector finally_vector;
1384 UsageVector finally_origins;
1388 public FlowBranchingException (FlowBranching parent,
1389 ExceptionStatement stmt)
1390 : base (parent, BranchingType.Exception, SiblingType.Try,
1394 this.emit_finally = true;
1397 protected override void AddSibling (UsageVector sibling)
1399 if (sibling.Type == SiblingType.Try) {
1400 sibling.Next = catch_vectors;
1401 catch_vectors = sibling;
1403 } else if (sibling.Type == SiblingType.Catch) {
1404 sibling.Next = catch_vectors;
1405 catch_vectors = sibling;
1407 } else if (sibling.Type == SiblingType.Finally) {
1408 sibling.MergeFinallyOrigins (finally_origins);
1409 finally_vector = sibling;
1412 throw new InvalidOperationException ();
1414 current_vector = sibling;
1417 public override UsageVector CurrentUsageVector {
1418 get { return current_vector; }
1421 public override bool InTryOrCatch (bool is_return)
1423 return finally_vector == null;
1426 public override bool InCatch ()
1428 return !in_try && (finally_vector == null);
1431 public override bool InFinally (bool is_return)
1433 return finally_vector != null;
1436 public override bool BreakCrossesTryCatchBoundary ()
1441 public override void AddFinallyVector (UsageVector vector)
1443 vector = vector.Clone ();
1444 vector.Next = finally_origins;
1445 finally_origins = vector;
1448 public override void StealFinallyClauses (ref ArrayList list)
1451 list = new ArrayList ();
1453 emit_finally = false;
1454 base.StealFinallyClauses (ref list);
1457 public bool EmitFinally {
1458 get { return emit_finally; }
1461 public override LabeledStatement LookupLabel (string name, Location loc)
1463 if (current_vector.Block == null)
1464 return base.LookupLabel (name, loc);
1466 LabeledStatement s = current_vector.Block.LookupLabel (name);
1470 if (finally_vector != null) {
1472 157, loc, "Control can not leave the body " +
1473 "of the finally block");
1477 return base.LookupLabel (name, loc);
1480 public override void Label (UsageVector origin_vectors)
1482 CurrentUsageVector.MergeJumpOrigins (origin_vectors);
1485 protected override UsageVector Merge ()
1487 UsageVector vector = Merge (catch_vectors);
1489 vector.MergeFinally (this, finally_vector, finally_origins);
1496 // This is used by the flow analysis code to keep track of the type of local variables
1499 // The flow code uses a BitVector to keep track of whether a variable has been assigned
1500 // or not. This is easy for fundamental types (int, char etc.) or reference types since
1501 // you can only assign the whole variable as such.
1503 // For structs, we also need to keep track of all its fields. To do this, we allocate one
1504 // bit for the struct itself (it's used if you assign/access the whole struct) followed by
1505 // one bit for each of its fields.
1507 // This class computes this `layout' for each type.
1509 public class TypeInfo
1511 public readonly Type Type;
1514 // Total number of bits a variable of this type consumes in the flow vector.
1516 public readonly int TotalLength;
1519 // Number of bits the simple fields of a variable of this type consume
1520 // in the flow vector.
1522 public readonly int Length;
1525 // This is only used by sub-structs.
1527 public readonly int Offset;
1530 // If this is a struct.
1532 public readonly bool IsStruct;
1535 // If this is a struct, all fields which are structs theirselves.
1537 public TypeInfo[] SubStructInfo;
1539 protected readonly StructInfo struct_info;
1540 private static Hashtable type_hash = new Hashtable ();
1542 public static TypeInfo GetTypeInfo (Type type)
1544 TypeInfo info = (TypeInfo) type_hash [type];
1548 info = new TypeInfo (type);
1549 type_hash.Add (type, info);
1553 public static TypeInfo GetTypeInfo (TypeContainer tc)
1555 TypeInfo info = (TypeInfo) type_hash [tc.TypeBuilder];
1559 info = new TypeInfo (tc);
1560 type_hash.Add (tc.TypeBuilder, info);
1564 private TypeInfo (Type type)
1568 struct_info = StructInfo.GetStructInfo (type);
1569 if (struct_info != null) {
1570 Length = struct_info.Length;
1571 TotalLength = struct_info.TotalLength;
1572 SubStructInfo = struct_info.StructFields;
1581 private TypeInfo (TypeContainer tc)
1583 this.Type = tc.TypeBuilder;
1585 struct_info = StructInfo.GetStructInfo (tc);
1586 if (struct_info != null) {
1587 Length = struct_info.Length;
1588 TotalLength = struct_info.TotalLength;
1589 SubStructInfo = struct_info.StructFields;
1598 protected TypeInfo (StructInfo struct_info, int offset)
1600 this.struct_info = struct_info;
1601 this.Offset = offset;
1602 this.Length = struct_info.Length;
1603 this.TotalLength = struct_info.TotalLength;
1604 this.SubStructInfo = struct_info.StructFields;
1605 this.Type = struct_info.Type;
1606 this.IsStruct = true;
1609 public int GetFieldIndex (string name)
1611 if (struct_info == null)
1614 return struct_info [name];
1617 public TypeInfo GetSubStruct (string name)
1619 if (struct_info == null)
1622 return struct_info.GetStructField (name);
1626 // A struct's constructor must always assign all fields.
1627 // This method checks whether it actually does so.
1629 public bool IsFullyInitialized (FlowBranching branching, VariableInfo vi, Location loc)
1631 if (struct_info == null)
1635 for (int i = 0; i < struct_info.Count; i++) {
1636 FieldInfo field = struct_info.Fields [i];
1638 if (!branching.IsFieldAssigned (vi, field.Name)) {
1639 Report.Error (171, loc,
1640 "Field `" + TypeManager.CSharpName (Type) +
1641 "." + field.Name + "' must be fully initialized " +
1642 "before control leaves the constructor");
1650 public override string ToString ()
1652 return String.Format ("TypeInfo ({0}:{1}:{2}:{3})",
1653 Type, Offset, Length, TotalLength);
1656 protected class StructInfo {
1657 public readonly Type Type;
1658 public readonly FieldInfo[] Fields;
1659 public readonly TypeInfo[] StructFields;
1660 public readonly int Count;
1661 public readonly int CountPublic;
1662 public readonly int CountNonPublic;
1663 public readonly int Length;
1664 public readonly int TotalLength;
1665 public readonly bool HasStructFields;
1667 private static Hashtable field_type_hash = new Hashtable ();
1668 private Hashtable struct_field_hash;
1669 private Hashtable field_hash;
1671 protected bool InTransit = false;
1673 // Private constructor. To save memory usage, we only need to create one instance
1674 // of this class per struct type.
1675 private StructInfo (Type type)
1679 field_type_hash.Add (type, this);
1681 if (type is TypeBuilder) {
1682 TypeContainer tc = TypeManager.LookupTypeContainer (type);
1684 ArrayList fields = null;
1688 ArrayList public_fields = new ArrayList ();
1689 ArrayList non_public_fields = new ArrayList ();
1691 if (fields != null) {
1692 foreach (FieldMember field in fields) {
1693 if ((field.ModFlags & Modifiers.STATIC) != 0)
1695 if ((field.ModFlags & Modifiers.PUBLIC) != 0)
1696 public_fields.Add (field.FieldBuilder);
1698 non_public_fields.Add (field.FieldBuilder);
1702 CountPublic = public_fields.Count;
1703 CountNonPublic = non_public_fields.Count;
1704 Count = CountPublic + CountNonPublic;
1706 Fields = new FieldInfo [Count];
1707 public_fields.CopyTo (Fields, 0);
1708 non_public_fields.CopyTo (Fields, CountPublic);
1710 FieldInfo[] public_fields = type.GetFields (
1711 BindingFlags.Instance|BindingFlags.Public);
1712 FieldInfo[] non_public_fields = type.GetFields (
1713 BindingFlags.Instance|BindingFlags.NonPublic);
1715 CountPublic = public_fields.Length;
1716 CountNonPublic = non_public_fields.Length;
1717 Count = CountPublic + CountNonPublic;
1719 Fields = new FieldInfo [Count];
1720 public_fields.CopyTo (Fields, 0);
1721 non_public_fields.CopyTo (Fields, CountPublic);
1724 struct_field_hash = new Hashtable ();
1725 field_hash = new Hashtable ();
1728 StructFields = new TypeInfo [Count];
1729 StructInfo[] sinfo = new StructInfo [Count];
1733 for (int i = 0; i < Count; i++) {
1734 FieldInfo field = (FieldInfo) Fields [i];
1736 sinfo [i] = GetStructInfo (field.FieldType);
1737 if (sinfo [i] == null)
1738 field_hash.Add (field.Name, ++Length);
1739 else if (sinfo [i].InTransit) {
1740 Report.Error (523, String.Format (
1741 "Struct member '{0}.{1}' of type '{2}' causes " +
1742 "a cycle in the structure layout",
1743 type, field.Name, sinfo [i].Type));
1751 TotalLength = Length + 1;
1752 for (int i = 0; i < Count; i++) {
1753 FieldInfo field = (FieldInfo) Fields [i];
1755 if (sinfo [i] == null)
1758 field_hash.Add (field.Name, TotalLength);
1760 HasStructFields = true;
1761 StructFields [i] = new TypeInfo (sinfo [i], TotalLength);
1762 struct_field_hash.Add (field.Name, StructFields [i]);
1763 TotalLength += sinfo [i].TotalLength;
1767 public int this [string name] {
1769 if (field_hash.Contains (name))
1770 return (int) field_hash [name];
1776 public TypeInfo GetStructField (string name)
1778 return (TypeInfo) struct_field_hash [name];
1781 public static StructInfo GetStructInfo (Type type)
1783 if (!TypeManager.IsValueType (type) || TypeManager.IsEnumType (type) ||
1784 TypeManager.IsBuiltinType (type))
1787 StructInfo info = (StructInfo) field_type_hash [type];
1791 return new StructInfo (type);
1794 public static StructInfo GetStructInfo (TypeContainer tc)
1796 StructInfo info = (StructInfo) field_type_hash [tc.TypeBuilder];
1800 return new StructInfo (tc.TypeBuilder);
1806 // This is used by the flow analysis code to store information about a single local variable
1807 // or parameter. Depending on the variable's type, we need to allocate one or more elements
1808 // in the BitVector - if it's a fundamental or reference type, we just need to know whether
1809 // it has been assigned or not, but for structs, we need this information for each of its fields.
1811 public class VariableInfo {
1812 public readonly string Name;
1813 public readonly TypeInfo TypeInfo;
1816 // The bit offset of this variable in the flow vector.
1818 public readonly int Offset;
1821 // The number of bits this variable needs in the flow vector.
1822 // The first bit always specifies whether the variable as such has been assigned while
1823 // the remaining bits contain this information for each of a struct's fields.
1825 public readonly int Length;
1828 // If this is a parameter of local variable.
1830 public readonly bool IsParameter;
1832 public readonly LocalInfo LocalInfo;
1833 public readonly int ParameterIndex;
1835 readonly VariableInfo Parent;
1836 VariableInfo[] sub_info;
1838 protected VariableInfo (string name, Type type, int offset)
1841 this.Offset = offset;
1842 this.TypeInfo = TypeInfo.GetTypeInfo (type);
1844 Length = TypeInfo.TotalLength;
1849 protected VariableInfo (VariableInfo parent, TypeInfo type)
1851 this.Name = parent.Name;
1852 this.TypeInfo = type;
1853 this.Offset = parent.Offset + type.Offset;
1854 this.Parent = parent;
1855 this.Length = type.TotalLength;
1857 this.IsParameter = parent.IsParameter;
1858 this.LocalInfo = parent.LocalInfo;
1859 this.ParameterIndex = parent.ParameterIndex;
1864 protected void Initialize ()
1866 TypeInfo[] sub_fields = TypeInfo.SubStructInfo;
1867 if (sub_fields != null) {
1868 sub_info = new VariableInfo [sub_fields.Length];
1869 for (int i = 0; i < sub_fields.Length; i++) {
1870 if (sub_fields [i] != null)
1871 sub_info [i] = new VariableInfo (this, sub_fields [i]);
1874 sub_info = new VariableInfo [0];
1877 public VariableInfo (LocalInfo local_info, int offset)
1878 : this (local_info.Name, local_info.VariableType, offset)
1880 this.LocalInfo = local_info;
1881 this.IsParameter = false;
1884 public VariableInfo (string name, Type type, int param_idx, int offset)
1885 : this (name, type, offset)
1887 this.ParameterIndex = param_idx;
1888 this.IsParameter = true;
1891 public bool IsAssigned (EmitContext ec)
1893 return !ec.DoFlowAnalysis || ec.CurrentBranching.IsAssigned (this);
1896 public bool IsAssigned (EmitContext ec, Location loc)
1898 if (IsAssigned (ec))
1901 Report.Error (165, loc,
1902 "Use of unassigned local variable `" + Name + "'");
1903 ec.CurrentBranching.SetAssigned (this);
1907 public bool IsAssigned (MyBitVector vector)
1909 if (vector [Offset])
1912 for (VariableInfo parent = Parent; parent != null; parent = parent.Parent)
1913 if (vector [parent.Offset])
1916 // Return unless this is a struct.
1917 if (!TypeInfo.IsStruct)
1920 // Ok, so each field must be assigned.
1921 for (int i = 0; i < TypeInfo.Length; i++) {
1922 if (!vector [Offset + i + 1])
1926 // Ok, now check all fields which are structs.
1927 for (int i = 0; i < sub_info.Length; i++) {
1928 VariableInfo sinfo = sub_info [i];
1932 if (!sinfo.IsAssigned (vector))
1936 vector [Offset] = true;
1940 public void SetAssigned (EmitContext ec)
1942 if (ec.DoFlowAnalysis)
1943 ec.CurrentBranching.SetAssigned (this);
1946 public void SetAssigned (MyBitVector vector)
1948 vector [Offset] = true;
1951 public bool IsFieldAssigned (EmitContext ec, string name, Location loc)
1953 if (!ec.DoFlowAnalysis || ec.CurrentBranching.IsFieldAssigned (this, name))
1956 Report.Error (170, loc,
1957 "Use of possibly unassigned field `" + name + "'");
1958 ec.CurrentBranching.SetFieldAssigned (this, name);
1962 public bool IsFieldAssigned (MyBitVector vector, string field_name)
1964 int field_idx = TypeInfo.GetFieldIndex (field_name);
1969 return vector [Offset + field_idx];
1972 public void SetFieldAssigned (EmitContext ec, string name)
1974 if (ec.DoFlowAnalysis)
1975 ec.CurrentBranching.SetFieldAssigned (this, name);
1978 public void SetFieldAssigned (MyBitVector vector, string field_name)
1980 int field_idx = TypeInfo.GetFieldIndex (field_name);
1985 vector [Offset + field_idx] = true;
1988 public VariableInfo GetSubStruct (string name)
1990 TypeInfo type = TypeInfo.GetSubStruct (name);
1995 return new VariableInfo (this, type);
1998 public override string ToString ()
2000 return String.Format ("VariableInfo ({0}:{1}:{2}:{3}:{4})",
2001 Name, TypeInfo, Offset, Length, IsParameter);
2006 // This is used by the flow code to hold the `layout' of the flow vector for
2007 // all locals and all parameters (ie. we create one instance of this class for the
2008 // locals and another one for the params).
2010 public class VariableMap {
2012 // The number of variables in the map.
2014 public readonly int Count;
2017 // Total length of the flow vector for this map.
2019 public readonly int Length;
2023 public VariableMap (InternalParameters ip)
2025 Count = ip != null ? ip.Count : 0;
2027 // Dont bother allocating anything!
2033 for (int i = 0; i < Count; i++) {
2034 Parameter.Modifier mod = ip.ParameterModifier (i);
2036 if ((mod & Parameter.Modifier.OUT) == 0)
2039 // Dont allocate till we find an out var.
2041 map = new VariableInfo [Count];
2043 map [i] = new VariableInfo (ip.ParameterName (i),
2044 TypeManager.GetElementType (ip.ParameterType (i)), i, Length);
2046 Length += map [i].Length;
2050 public VariableMap (LocalInfo[] locals)
2051 : this (null, locals)
2054 public VariableMap (VariableMap parent, LocalInfo[] locals)
2056 int offset = 0, start = 0;
2057 if (parent != null && parent.map != null) {
2058 offset = parent.Length;
2059 start = parent.Count;
2062 Count = locals.Length + start;
2067 map = new VariableInfo [Count];
2070 if (parent != null && parent.map != null) {
2071 parent.map.CopyTo (map, 0);
2074 for (int i = start; i < Count; i++) {
2075 LocalInfo li = locals [i-start];
2077 if (li.VariableType == null)
2080 map [i] = li.VariableInfo = new VariableInfo (li, Length);
2081 Length += map [i].Length;
2086 // Returns the VariableInfo for variable @index or null if we don't need to
2087 // compute assignment info for this variable.
2089 public VariableInfo this [int index] {
2098 public override string ToString ()
2100 return String.Format ("VariableMap ({0}:{1})", Count, Length);
2105 // This is a special bit vector which can inherit from another bit vector doing a
2106 // copy-on-write strategy. The inherited vector may have a smaller size than the
2109 public class MyBitVector {
2110 public readonly int Count;
2111 public readonly MyBitVector InheritsFrom;
2116 public MyBitVector (int Count)
2117 : this (null, Count)
2120 public MyBitVector (MyBitVector InheritsFrom, int Count)
2122 this.InheritsFrom = InheritsFrom;
2127 // Checks whether this bit vector has been modified. After setting this to true,
2128 // we won't use the inherited vector anymore, but our own copy of it.
2130 public bool IsDirty {
2137 initialize_vector ();
2142 // Get/set bit `index' in the bit vector.
2144 public bool this [int index]
2148 throw new ArgumentOutOfRangeException ();
2150 // We're doing a "copy-on-write" strategy here; as long
2151 // as nobody writes to the array, we can use our parent's
2152 // copy instead of duplicating the vector.
2155 return vector [index];
2156 else if (InheritsFrom != null) {
2157 BitArray inherited = InheritsFrom.Vector;
2159 if (index < inherited.Count)
2160 return inherited [index];
2169 throw new ArgumentOutOfRangeException ();
2171 // Only copy the vector if we're actually modifying it.
2173 if (this [index] != value) {
2174 initialize_vector ();
2176 vector [index] = value;
2182 // If you explicitly convert the MyBitVector to a BitArray, you will get a deep
2183 // copy of the bit vector.
2185 public static explicit operator BitArray (MyBitVector vector)
2187 vector.initialize_vector ();
2188 return vector.Vector;
2192 // Performs an `or' operation on the bit vector. The `new_vector' may have a
2193 // different size than the current one.
2195 public void Or (MyBitVector new_vector)
2197 BitArray new_array = new_vector.Vector;
2199 initialize_vector ();
2202 if (vector.Count < new_array.Count)
2203 upper = vector.Count;
2205 upper = new_array.Count;
2207 for (int i = 0; i < upper; i++)
2208 vector [i] = vector [i] | new_array [i];
2212 // Perfonrms an `and' operation on the bit vector. The `new_vector' may have
2213 // a different size than the current one.
2215 public void And (MyBitVector new_vector)
2217 BitArray new_array = new_vector.Vector;
2219 initialize_vector ();
2222 if (vector.Count < new_array.Count)
2223 lower = upper = vector.Count;
2225 lower = new_array.Count;
2226 upper = vector.Count;
2229 for (int i = 0; i < lower; i++)
2230 vector [i] = vector [i] & new_array [i];
2232 for (int i = lower; i < upper; i++)
2236 public static void And (ref MyBitVector target, MyBitVector vector)
2239 target.And (vector);
2241 target = vector.Clone ();
2244 public static void Or (ref MyBitVector target, MyBitVector vector)
2249 target = vector.Clone ();
2253 // This does a deep copy of the bit vector.
2255 public MyBitVector Clone ()
2257 MyBitVector retval = new MyBitVector (Count);
2259 retval.Vector = Vector;
2268 else if (!is_dirty && (InheritsFrom != null))
2269 return InheritsFrom.Vector;
2271 initialize_vector ();
2277 initialize_vector ();
2279 for (int i = 0; i < System.Math.Min (vector.Count, value.Count); i++)
2280 vector [i] = value [i];
2284 void initialize_vector ()
2289 vector = new BitArray (Count, false);
2290 if (InheritsFrom != null)
2291 Vector = InheritsFrom.Vector;
2296 public override string ToString ()
2298 StringBuilder sb = new StringBuilder ("{");
2300 BitArray vector = Vector;
2303 for (int i = 0; i < vector.Count; i++) {
2304 sb.Append (vector [i] ? "1" : "0");
2308 return sb.ToString ();