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 } else if (branching.Type == BranchingType.Switch) {
664 if (new_r.MayBreak || new_r.MayReturn)
665 new_r.ResetBarrier ();
667 new_r.ResetBreaks ();
671 // We've now either reached the point after the branching or we will
672 // never get there since we always return or always throw an exception.
674 // If we can reach the point after the branching, mark all locals and
675 // parameters as initialized which have been initialized in all branches
676 // we need to look at (see above).
679 if ((Type == SiblingType.SwitchSection) && !new_r.IsUnreachable) {
680 Report.Error (163, Location,
681 "Control cannot fall through from one " +
682 "case label to another");
686 if (locals != null && result.LocalVector != null)
687 locals.Or (result.LocalVector);
689 if (result.ParameterVector != null)
690 parameters.Or (result.ParameterVector);
692 reachability.Or (new_r);
694 Report.Debug (2, " MERGING CHILD DONE", this, result,
695 new_r, reachability);
702 protected void MergeFinally (FlowBranching branching, UsageVector f_origins,
703 MyBitVector f_params)
705 for (UsageVector vector = f_origins; vector != null; vector = vector.Next) {
706 MyBitVector temp_params = f_params.Clone ();
707 temp_params.Or (vector.Parameters);
711 public void MergeFinally (FlowBranching branching, UsageVector f_vector,
712 UsageVector f_origins)
714 if (parameters != null) {
715 if (f_vector != null) {
716 MergeFinally (branching, f_origins, f_vector.Parameters);
717 MyBitVector.Or (ref parameters, f_vector.ParameterVector);
719 MergeFinally (branching, f_origins, parameters);
722 if (f_vector != null && f_vector.LocalVector != null)
723 MyBitVector.Or (ref locals, f_vector.LocalVector);
727 // Tells control flow analysis that the current code position may be reached with
728 // a forward jump from any of the origins listed in `origin_vectors' which is a
729 // list of UsageVectors.
731 // This is used when resolving forward gotos - in the following example, the
732 // variable `a' is uninitialized in line 8 becase this line may be reached via
733 // the goto in line 4:
743 // 8 Console.WriteLine (a);
746 public void MergeJumpOrigins (UsageVector o_vectors)
748 Report.Debug (1, " MERGING JUMP ORIGINS", this);
750 reachability = Reachability.Never ();
752 if (o_vectors == null) {
753 reachability.SetBarrier ();
759 for (UsageVector vector = o_vectors; vector != null;
760 vector = vector.Next) {
761 Report.Debug (1, " MERGING JUMP ORIGIN", vector);
764 if (locals != null && vector.Locals != null)
765 locals.Or (vector.locals);
767 if (parameters != null)
768 parameters.Or (vector.parameters);
771 if (locals != null && vector.Locals != null)
772 locals.And (vector.locals);
773 if (parameters != null)
774 parameters.And (vector.parameters);
777 Reachability.And (ref reachability, vector.Reachability, true);
780 Report.Debug (1, " MERGING JUMP ORIGINS DONE", this);
784 // This is used at the beginning of a finally block if there were
785 // any return statements in the try block or one of the catch blocks.
787 public void MergeFinallyOrigins (UsageVector f_origins)
789 Report.Debug (1, " MERGING FINALLY ORIGIN", this);
791 reachability = Reachability.Never ();
793 for (UsageVector vector = f_origins; vector != null; vector = vector.Next) {
794 Report.Debug (1, " MERGING FINALLY ORIGIN", vector);
796 if (parameters != null)
797 parameters.And (vector.parameters);
799 Reachability.And (ref reachability, vector.Reachability, true);
802 Report.Debug (1, " MERGING FINALLY ORIGIN DONE", this);
805 public void MergeBreakOrigins (UsageVector o_vectors)
807 Report.Debug (1, " MERGING BREAK ORIGINS", this);
809 if (o_vectors == null)
814 for (UsageVector vector = o_vectors; vector != null;
815 vector = vector.Next) {
816 Report.Debug (1, " MERGING BREAK ORIGIN", vector);
819 if (locals != null && vector.Locals != null)
820 locals.Or (vector.locals);
822 if (parameters != null)
823 parameters.Or (vector.parameters);
826 if (locals != null && vector.Locals != null)
827 locals.And (vector.locals);
828 if (parameters != null)
829 parameters.And (vector.parameters);
833 Report.Debug (1, " MERGING BREAK ORIGINS DONE", this);
836 public void CheckOutParameters (FlowBranching branching)
838 if (parameters != null)
839 branching.CheckOutParameters (parameters, branching.Location);
843 // Performs an `or' operation on the locals and the parameters.
845 public void Or (UsageVector new_vector)
848 locals.Or (new_vector.locals);
849 if (parameters != null)
850 parameters.Or (new_vector.parameters);
854 // Performs an `and' operation on the locals.
856 public void AndLocals (UsageVector new_vector)
859 locals.And (new_vector.locals);
862 public bool HasParameters {
864 return parameters != null;
868 public bool HasLocals {
870 return locals != null;
875 // Returns a deep copy of the parameters.
877 public MyBitVector Parameters {
879 if (parameters != null)
880 return parameters.Clone ();
887 // Returns a deep copy of the locals.
889 public MyBitVector Locals {
892 return locals.Clone ();
898 public MyBitVector ParameterVector {
904 public MyBitVector LocalVector {
914 public override string ToString ()
916 StringBuilder sb = new StringBuilder ();
918 sb.Append ("Vector (");
925 sb.Append (reachability);
926 if (parameters != null) {
928 sb.Append (parameters);
934 return sb.ToString ();
939 // Creates a new flow branching which is contained in `parent'.
940 // You should only pass non-null for the `block' argument if this block
941 // introduces any new variables - in this case, we need to create a new
942 // usage vector with a different size than our parent's one.
944 protected FlowBranching (FlowBranching parent, BranchingType type, SiblingType stype,
945 Block block, Location loc)
955 param_map = Block.ParameterMap;
956 local_map = Block.LocalMap;
958 UsageVector parent_vector = parent != null ? parent.CurrentUsageVector : null;
959 vector = new UsageVector (
960 stype, parent_vector, Block, loc,
961 param_map.Length, local_map.Length);
963 param_map = Parent.param_map;
964 local_map = Parent.local_map;
965 vector = new UsageVector (
966 stype, Parent.CurrentUsageVector, null, loc);
972 public abstract UsageVector CurrentUsageVector {
977 // Creates a sibling of the current usage vector.
979 public virtual void CreateSibling (Block block, SiblingType type)
981 UsageVector vector = new UsageVector (
982 type, Parent.CurrentUsageVector, block, Location);
985 Report.Debug (1, " CREATED SIBLING", CurrentUsageVector);
988 public void CreateSibling ()
990 CreateSibling (null, SiblingType.Conditional);
993 protected abstract void AddSibling (UsageVector uv);
995 public virtual LabeledStatement LookupLabel (string name, Location loc)
998 return Parent.LookupLabel (name, loc);
1002 "No such label `" + name + "' in this scope");
1006 public abstract void Label (UsageVector origin_vectors);
1009 // Check whether all `out' parameters have been assigned.
1011 public void CheckOutParameters (MyBitVector parameters, Location loc)
1013 for (int i = 0; i < param_map.Count; i++) {
1014 VariableInfo var = param_map [i];
1019 if (var.IsAssigned (parameters))
1022 Report.Error (177, loc, "The out parameter `" +
1023 var.Name + "' must be " +
1024 "assigned before control leaves the current method.");
1028 protected UsageVector Merge (UsageVector sibling_list)
1030 if (sibling_list.Next == null)
1031 return sibling_list;
1033 MyBitVector locals = null;
1034 MyBitVector parameters = null;
1036 Reachability reachability = null;
1038 Report.Debug (2, " MERGING SIBLINGS", this, Name);
1040 for (UsageVector child = sibling_list; child != null; child = child.Next) {
1041 bool do_break = (Type != BranchingType.Switch) &&
1042 (Type != BranchingType.Loop);
1044 Report.Debug (2, " MERGING SIBLING ", child,
1045 child.ParameterVector, child.LocalVector,
1046 reachability, child.Reachability, do_break);
1048 Reachability.And (ref reachability, child.Reachability, do_break);
1050 // A local variable is initialized after a flow branching if it
1051 // has been initialized in all its branches which do neither
1052 // always return or always throw an exception.
1054 // If a branch may return, but does not always return, then we
1055 // can treat it like a never-returning branch here: control will
1056 // only reach the code position after the branching if we did not
1059 // It's important to distinguish between always and sometimes
1060 // returning branches here:
1063 // 2 if (something) {
1067 // 6 Console.WriteLine (a);
1069 // The if block in lines 3-4 always returns, so we must not look
1070 // at the initialization of `a' in line 4 - thus it'll still be
1071 // uninitialized in line 6.
1073 // On the other hand, the following is allowed:
1080 // 6 Console.WriteLine (a);
1082 // Here, `a' is initialized in line 3 and we must not look at
1083 // line 5 since it always returns.
1085 bool do_break_2 = (child.Type != SiblingType.Block) &&
1086 (child.Type != SiblingType.SwitchSection);
1087 bool always_throws = (child.Type != SiblingType.Try) &&
1088 child.Reachability.AlwaysThrows;
1089 bool unreachable = always_throws ||
1090 (do_break_2 && child.Reachability.AlwaysBreaks) ||
1091 child.Reachability.AlwaysReturns ||
1092 child.Reachability.AlwaysHasBarrier;
1094 Report.Debug (2, " MERGING SIBLING #1", reachability,
1095 Type, child.Type, child.Reachability.IsUnreachable,
1096 do_break_2, always_throws, unreachable);
1098 if (!unreachable && (child.LocalVector != null))
1099 MyBitVector.And (ref locals, child.LocalVector);
1101 // An `out' parameter must be assigned in all branches which do
1102 // not always throw an exception.
1103 if ((child.ParameterVector != null) && !child.Reachability.AlwaysThrows)
1104 MyBitVector.And (ref parameters, child.ParameterVector);
1106 Report.Debug (2, " MERGING SIBLING #2", parameters, locals);
1109 if (reachability == null)
1110 reachability = Reachability.Never ();
1112 Report.Debug (2, " MERGING SIBLINGS DONE", parameters, locals,
1113 reachability, Infinite);
1115 return new UsageVector (
1116 parameters, locals, reachability, null, Location);
1119 protected abstract UsageVector Merge ();
1122 // Merge a child branching.
1124 public UsageVector MergeChild (FlowBranching child)
1126 return CurrentUsageVector.MergeChild (child);
1130 // Does the toplevel merging.
1132 public Reachability MergeTopBlock ()
1134 if ((Type != BranchingType.Block) || (Block == null))
1135 throw new NotSupportedException ();
1137 UsageVector vector = new UsageVector (
1138 SiblingType.Conditional, null, Block, Location,
1139 param_map.Length, local_map.Length);
1141 UsageVector result = vector.MergeChild (this);
1143 Report.Debug (4, "MERGE TOP BLOCK", Location, vector, result.Reachability);
1145 if ((vector.Reachability.Throws != FlowReturns.Always) &&
1146 (vector.Reachability.Barrier != FlowReturns.Always))
1147 CheckOutParameters (vector.Parameters, Location);
1149 return result.Reachability;
1153 // Checks whether we're in a `try' block.
1155 public virtual bool InTryOrCatch (bool is_return)
1157 if ((Block != null) && Block.IsDestructor)
1159 else if (!is_return &&
1160 ((Type == BranchingType.Loop) || (Type == BranchingType.Switch)))
1162 else if (Parent != null)
1163 return Parent.InTryOrCatch (is_return);
1169 // Checks whether we're in a `catch' block.
1171 public virtual bool InCatch ()
1174 return Parent.InCatch ();
1180 // Checks whether we're in a `finally' block.
1182 public virtual bool InFinally (bool is_return)
1185 ((Type == BranchingType.Loop) || (Type == BranchingType.Switch)))
1187 else if (Parent != null)
1188 return Parent.InFinally (is_return);
1193 public virtual bool InLoop ()
1195 if (Type == BranchingType.Loop)
1197 else if (Parent != null)
1198 return Parent.InLoop ();
1203 public virtual bool InSwitch ()
1205 if (Type == BranchingType.Switch)
1207 else if (Parent != null)
1208 return Parent.InSwitch ();
1213 public virtual bool BreakCrossesTryCatchBoundary ()
1215 if ((Type == BranchingType.Loop) || (Type == BranchingType.Switch))
1217 else if (Parent != null)
1218 return Parent.BreakCrossesTryCatchBoundary ();
1223 public virtual void AddFinallyVector (UsageVector vector)
1226 Parent.AddFinallyVector (vector);
1227 else if ((Block == null) || !Block.IsDestructor)
1228 throw new NotSupportedException ();
1231 public virtual void AddBreakVector (UsageVector vector)
1234 Parent.AddBreakVector (vector);
1235 else if ((Block == null) || !Block.IsDestructor)
1236 throw new NotSupportedException ();
1239 public virtual void StealFinallyClauses (ref ArrayList list)
1242 Parent.StealFinallyClauses (ref list);
1245 public bool IsAssigned (VariableInfo vi)
1247 return CurrentUsageVector.IsAssigned (vi);
1250 public bool IsFieldAssigned (VariableInfo vi, string field_name)
1252 if (CurrentUsageVector.IsAssigned (vi))
1255 return CurrentUsageVector.IsFieldAssigned (vi, field_name);
1258 public void SetAssigned (VariableInfo vi)
1260 CurrentUsageVector.SetAssigned (vi);
1263 public void SetFieldAssigned (VariableInfo vi, string name)
1265 CurrentUsageVector.SetFieldAssigned (vi, name);
1268 public override string ToString ()
1270 StringBuilder sb = new StringBuilder ();
1271 sb.Append (GetType ());
1277 if (Block != null) {
1279 sb.Append (Block.ID);
1281 sb.Append (Block.StartLocation);
1284 // sb.Append (Siblings.Length);
1285 // sb.Append (" - ");
1286 sb.Append (CurrentUsageVector);
1288 return sb.ToString ();
1291 public string Name {
1293 return String.Format ("{0} ({1}:{2}:{3})",
1294 GetType (), id, Type, Location);
1299 public class FlowBranchingBlock : FlowBranching
1301 UsageVector sibling_list = null;
1303 public FlowBranchingBlock (FlowBranching parent, BranchingType type,
1304 SiblingType stype, Block block, Location loc)
1305 : base (parent, type, stype, block, loc)
1308 public override UsageVector CurrentUsageVector {
1309 get { return sibling_list; }
1312 protected override void AddSibling (UsageVector sibling)
1314 sibling.Next = sibling_list;
1315 sibling_list = sibling;
1318 public override LabeledStatement LookupLabel (string name, Location loc)
1321 return base.LookupLabel (name, loc);
1323 LabeledStatement s = Block.LookupLabel (name);
1327 return base.LookupLabel (name, loc);
1330 public override void Label (UsageVector origin_vectors)
1332 if (!CurrentUsageVector.Reachability.IsUnreachable) {
1333 UsageVector vector = CurrentUsageVector.Clone ();
1334 vector.Next = origin_vectors;
1335 origin_vectors = vector;
1338 CurrentUsageVector.MergeJumpOrigins (origin_vectors);
1341 protected override UsageVector Merge ()
1343 return Merge (sibling_list);
1347 public class FlowBranchingLoop : FlowBranchingBlock
1349 UsageVector break_origins;
1351 public FlowBranchingLoop (FlowBranching parent, Block block, Location loc)
1352 : base (parent, BranchingType.Loop, SiblingType.Conditional, block, loc)
1355 public override void AddBreakVector (UsageVector vector)
1357 vector = vector.Clone ();
1358 vector.Next = break_origins;
1359 break_origins = vector;
1362 protected override UsageVector Merge ()
1364 UsageVector vector = base.Merge ();
1366 vector.MergeBreakOrigins (break_origins);
1372 public class FlowBranchingException : FlowBranching
1374 ExceptionStatement stmt;
1375 UsageVector current_vector;
1376 UsageVector catch_vectors;
1377 UsageVector finally_vector;
1378 UsageVector finally_origins;
1382 public FlowBranchingException (FlowBranching parent,
1383 ExceptionStatement stmt)
1384 : base (parent, BranchingType.Exception, SiblingType.Try,
1388 this.emit_finally = true;
1391 protected override void AddSibling (UsageVector sibling)
1393 if (sibling.Type == SiblingType.Try) {
1394 sibling.Next = catch_vectors;
1395 catch_vectors = sibling;
1397 } else if (sibling.Type == SiblingType.Catch) {
1398 sibling.Next = catch_vectors;
1399 catch_vectors = sibling;
1401 } else if (sibling.Type == SiblingType.Finally) {
1402 sibling.MergeFinallyOrigins (finally_origins);
1403 finally_vector = sibling;
1406 throw new InvalidOperationException ();
1408 current_vector = sibling;
1411 public override UsageVector CurrentUsageVector {
1412 get { return current_vector; }
1415 public override bool InTryOrCatch (bool is_return)
1417 return finally_vector == null;
1420 public override bool InCatch ()
1422 return !in_try && (finally_vector == null);
1425 public override bool InFinally (bool is_return)
1427 return finally_vector != null;
1430 public override bool BreakCrossesTryCatchBoundary ()
1435 public override void AddFinallyVector (UsageVector vector)
1437 vector = vector.Clone ();
1438 vector.Next = finally_origins;
1439 finally_origins = vector;
1442 public override void StealFinallyClauses (ref ArrayList list)
1445 list = new ArrayList ();
1447 emit_finally = false;
1448 base.StealFinallyClauses (ref list);
1451 public bool EmitFinally {
1452 get { return emit_finally; }
1455 public override LabeledStatement LookupLabel (string name, Location loc)
1457 if (current_vector.Block == null)
1458 return base.LookupLabel (name, loc);
1460 LabeledStatement s = current_vector.Block.LookupLabel (name);
1464 if (finally_vector != null) {
1466 157, loc, "Control can not leave the body " +
1467 "of the finally block");
1471 return base.LookupLabel (name, loc);
1474 public override void Label (UsageVector origin_vectors)
1476 CurrentUsageVector.MergeJumpOrigins (origin_vectors);
1479 protected override UsageVector Merge ()
1481 UsageVector vector = Merge (catch_vectors);
1483 vector.MergeFinally (this, finally_vector, finally_origins);
1490 // This is used by the flow analysis code to keep track of the type of local variables
1493 // The flow code uses a BitVector to keep track of whether a variable has been assigned
1494 // or not. This is easy for fundamental types (int, char etc.) or reference types since
1495 // you can only assign the whole variable as such.
1497 // For structs, we also need to keep track of all its fields. To do this, we allocate one
1498 // bit for the struct itself (it's used if you assign/access the whole struct) followed by
1499 // one bit for each of its fields.
1501 // This class computes this `layout' for each type.
1503 public class TypeInfo
1505 public readonly Type Type;
1508 // Total number of bits a variable of this type consumes in the flow vector.
1510 public readonly int TotalLength;
1513 // Number of bits the simple fields of a variable of this type consume
1514 // in the flow vector.
1516 public readonly int Length;
1519 // This is only used by sub-structs.
1521 public readonly int Offset;
1524 // If this is a struct.
1526 public readonly bool IsStruct;
1529 // If this is a struct, all fields which are structs theirselves.
1531 public TypeInfo[] SubStructInfo;
1533 protected readonly StructInfo struct_info;
1534 private static Hashtable type_hash = new Hashtable ();
1536 public static TypeInfo GetTypeInfo (Type type)
1538 TypeInfo info = (TypeInfo) type_hash [type];
1542 info = new TypeInfo (type);
1543 type_hash.Add (type, info);
1547 public static TypeInfo GetTypeInfo (TypeContainer tc)
1549 TypeInfo info = (TypeInfo) type_hash [tc.TypeBuilder];
1553 info = new TypeInfo (tc);
1554 type_hash.Add (tc.TypeBuilder, info);
1558 private TypeInfo (Type type)
1562 struct_info = StructInfo.GetStructInfo (type);
1563 if (struct_info != null) {
1564 Length = struct_info.Length;
1565 TotalLength = struct_info.TotalLength;
1566 SubStructInfo = struct_info.StructFields;
1575 private TypeInfo (TypeContainer tc)
1577 this.Type = tc.TypeBuilder;
1579 struct_info = StructInfo.GetStructInfo (tc);
1580 if (struct_info != null) {
1581 Length = struct_info.Length;
1582 TotalLength = struct_info.TotalLength;
1583 SubStructInfo = struct_info.StructFields;
1592 protected TypeInfo (StructInfo struct_info, int offset)
1594 this.struct_info = struct_info;
1595 this.Offset = offset;
1596 this.Length = struct_info.Length;
1597 this.TotalLength = struct_info.TotalLength;
1598 this.SubStructInfo = struct_info.StructFields;
1599 this.Type = struct_info.Type;
1600 this.IsStruct = true;
1603 public int GetFieldIndex (string name)
1605 if (struct_info == null)
1608 return struct_info [name];
1611 public TypeInfo GetSubStruct (string name)
1613 if (struct_info == null)
1616 return struct_info.GetStructField (name);
1620 // A struct's constructor must always assign all fields.
1621 // This method checks whether it actually does so.
1623 public bool IsFullyInitialized (FlowBranching branching, VariableInfo vi, Location loc)
1625 if (struct_info == null)
1629 for (int i = 0; i < struct_info.Count; i++) {
1630 FieldInfo field = struct_info.Fields [i];
1632 if (!branching.IsFieldAssigned (vi, field.Name)) {
1633 Report.Error (171, loc,
1634 "Field `" + TypeManager.CSharpName (Type) +
1635 "." + field.Name + "' must be fully initialized " +
1636 "before control leaves the constructor");
1644 public override string ToString ()
1646 return String.Format ("TypeInfo ({0}:{1}:{2}:{3})",
1647 Type, Offset, Length, TotalLength);
1650 protected class StructInfo {
1651 public readonly Type Type;
1652 public readonly FieldInfo[] Fields;
1653 public readonly TypeInfo[] StructFields;
1654 public readonly int Count;
1655 public readonly int CountPublic;
1656 public readonly int CountNonPublic;
1657 public readonly int Length;
1658 public readonly int TotalLength;
1659 public readonly bool HasStructFields;
1661 private static Hashtable field_type_hash = new Hashtable ();
1662 private Hashtable struct_field_hash;
1663 private Hashtable field_hash;
1665 protected bool InTransit = false;
1667 // Private constructor. To save memory usage, we only need to create one instance
1668 // of this class per struct type.
1669 private StructInfo (Type type)
1673 field_type_hash.Add (type, this);
1675 if (type is TypeBuilder) {
1676 TypeContainer tc = TypeManager.LookupTypeContainer (type);
1678 ArrayList fields = tc.Fields;
1680 ArrayList public_fields = new ArrayList ();
1681 ArrayList non_public_fields = new ArrayList ();
1683 if (fields != null) {
1684 foreach (Field field in fields) {
1685 if ((field.ModFlags & Modifiers.STATIC) != 0)
1687 if ((field.ModFlags & Modifiers.PUBLIC) != 0)
1688 public_fields.Add (field.FieldBuilder);
1690 non_public_fields.Add (field.FieldBuilder);
1694 CountPublic = public_fields.Count;
1695 CountNonPublic = non_public_fields.Count;
1696 Count = CountPublic + CountNonPublic;
1698 Fields = new FieldInfo [Count];
1699 public_fields.CopyTo (Fields, 0);
1700 non_public_fields.CopyTo (Fields, CountPublic);
1701 } else if (type is GenericTypeParameterBuilder) {
1702 CountPublic = CountNonPublic = Count = 0;
1704 Fields = new FieldInfo [0];
1706 FieldInfo[] public_fields = type.GetFields (
1707 BindingFlags.Instance|BindingFlags.Public);
1708 FieldInfo[] non_public_fields = type.GetFields (
1709 BindingFlags.Instance|BindingFlags.NonPublic);
1711 CountPublic = public_fields.Length;
1712 CountNonPublic = non_public_fields.Length;
1713 Count = CountPublic + CountNonPublic;
1715 Fields = new FieldInfo [Count];
1716 public_fields.CopyTo (Fields, 0);
1717 non_public_fields.CopyTo (Fields, CountPublic);
1720 struct_field_hash = new Hashtable ();
1721 field_hash = new Hashtable ();
1724 StructFields = new TypeInfo [Count];
1725 StructInfo[] sinfo = new StructInfo [Count];
1729 for (int i = 0; i < Count; i++) {
1730 FieldInfo field = (FieldInfo) Fields [i];
1732 sinfo [i] = GetStructInfo (field.FieldType);
1733 if (sinfo [i] == null)
1734 field_hash.Add (field.Name, ++Length);
1735 else if (sinfo [i].InTransit) {
1736 Report.Error (523, String.Format (
1737 "Struct member '{0}.{1}' of type '{2}' causes " +
1738 "a cycle in the structure layout",
1739 type, field.Name, sinfo [i].Type));
1747 TotalLength = Length + 1;
1748 for (int i = 0; i < Count; i++) {
1749 FieldInfo field = (FieldInfo) Fields [i];
1751 if (sinfo [i] == null)
1754 field_hash.Add (field.Name, TotalLength);
1756 HasStructFields = true;
1757 StructFields [i] = new TypeInfo (sinfo [i], TotalLength);
1758 struct_field_hash.Add (field.Name, StructFields [i]);
1759 TotalLength += sinfo [i].TotalLength;
1763 public int this [string name] {
1765 if (field_hash.Contains (name))
1766 return (int) field_hash [name];
1772 public TypeInfo GetStructField (string name)
1774 return (TypeInfo) struct_field_hash [name];
1777 public static StructInfo GetStructInfo (Type type)
1779 if (!TypeManager.IsValueType (type) || TypeManager.IsEnumType (type) ||
1780 TypeManager.IsBuiltinType (type))
1783 StructInfo info = (StructInfo) field_type_hash [type];
1787 return new StructInfo (type);
1790 public static StructInfo GetStructInfo (TypeContainer tc)
1792 StructInfo info = (StructInfo) field_type_hash [tc.TypeBuilder];
1796 return new StructInfo (tc.TypeBuilder);
1802 // This is used by the flow analysis code to store information about a single local variable
1803 // or parameter. Depending on the variable's type, we need to allocate one or more elements
1804 // in the BitVector - if it's a fundamental or reference type, we just need to know whether
1805 // it has been assigned or not, but for structs, we need this information for each of its fields.
1807 public class VariableInfo {
1808 public readonly string Name;
1809 public readonly TypeInfo TypeInfo;
1812 // The bit offset of this variable in the flow vector.
1814 public readonly int Offset;
1817 // The number of bits this variable needs in the flow vector.
1818 // The first bit always specifies whether the variable as such has been assigned while
1819 // the remaining bits contain this information for each of a struct's fields.
1821 public readonly int Length;
1824 // If this is a parameter of local variable.
1826 public readonly bool IsParameter;
1828 public readonly LocalInfo LocalInfo;
1829 public readonly int ParameterIndex;
1831 readonly VariableInfo Parent;
1832 VariableInfo[] sub_info;
1834 protected VariableInfo (string name, Type type, int offset)
1837 this.Offset = offset;
1838 this.TypeInfo = TypeInfo.GetTypeInfo (type);
1840 Length = TypeInfo.TotalLength;
1845 protected VariableInfo (VariableInfo parent, TypeInfo type)
1847 this.Name = parent.Name;
1848 this.TypeInfo = type;
1849 this.Offset = parent.Offset + type.Offset;
1850 this.Parent = parent;
1851 this.Length = type.TotalLength;
1853 this.IsParameter = parent.IsParameter;
1854 this.LocalInfo = parent.LocalInfo;
1855 this.ParameterIndex = parent.ParameterIndex;
1860 protected void Initialize ()
1862 TypeInfo[] sub_fields = TypeInfo.SubStructInfo;
1863 if (sub_fields != null) {
1864 sub_info = new VariableInfo [sub_fields.Length];
1865 for (int i = 0; i < sub_fields.Length; i++) {
1866 if (sub_fields [i] != null)
1867 sub_info [i] = new VariableInfo (this, sub_fields [i]);
1870 sub_info = new VariableInfo [0];
1873 public VariableInfo (LocalInfo local_info, int offset)
1874 : this (local_info.Name, local_info.VariableType, offset)
1876 this.LocalInfo = local_info;
1877 this.IsParameter = false;
1880 public VariableInfo (string name, Type type, int param_idx, int offset)
1881 : this (name, type, offset)
1883 this.ParameterIndex = param_idx;
1884 this.IsParameter = true;
1887 public bool IsAssigned (EmitContext ec)
1889 return !ec.DoFlowAnalysis || ec.CurrentBranching.IsAssigned (this);
1892 public bool IsAssigned (EmitContext ec, Location loc)
1894 if (IsAssigned (ec))
1897 Report.Error (165, loc,
1898 "Use of unassigned local variable `" + Name + "'");
1899 ec.CurrentBranching.SetAssigned (this);
1903 public bool IsAssigned (MyBitVector vector)
1905 if (vector [Offset])
1908 for (VariableInfo parent = Parent; parent != null; parent = parent.Parent)
1909 if (vector [parent.Offset])
1912 // Return unless this is a struct.
1913 if (!TypeInfo.IsStruct)
1916 // Ok, so each field must be assigned.
1917 for (int i = 0; i < TypeInfo.Length; i++) {
1918 if (!vector [Offset + i + 1])
1922 // Ok, now check all fields which are structs.
1923 for (int i = 0; i < sub_info.Length; i++) {
1924 VariableInfo sinfo = sub_info [i];
1928 if (!sinfo.IsAssigned (vector))
1932 vector [Offset] = true;
1936 public void SetAssigned (EmitContext ec)
1938 if (ec.DoFlowAnalysis)
1939 ec.CurrentBranching.SetAssigned (this);
1942 public void SetAssigned (MyBitVector vector)
1944 vector [Offset] = true;
1947 public bool IsFieldAssigned (EmitContext ec, string name, Location loc)
1949 if (!ec.DoFlowAnalysis || ec.CurrentBranching.IsFieldAssigned (this, name))
1952 Report.Error (170, loc,
1953 "Use of possibly unassigned field `" + name + "'");
1954 ec.CurrentBranching.SetFieldAssigned (this, name);
1958 public bool IsFieldAssigned (MyBitVector vector, string field_name)
1960 int field_idx = TypeInfo.GetFieldIndex (field_name);
1965 return vector [Offset + field_idx];
1968 public void SetFieldAssigned (EmitContext ec, string name)
1970 if (ec.DoFlowAnalysis)
1971 ec.CurrentBranching.SetFieldAssigned (this, name);
1974 public void SetFieldAssigned (MyBitVector vector, string field_name)
1976 int field_idx = TypeInfo.GetFieldIndex (field_name);
1981 vector [Offset + field_idx] = true;
1984 public VariableInfo GetSubStruct (string name)
1986 TypeInfo type = TypeInfo.GetSubStruct (name);
1991 return new VariableInfo (this, type);
1994 public override string ToString ()
1996 return String.Format ("VariableInfo ({0}:{1}:{2}:{3}:{4})",
1997 Name, TypeInfo, Offset, Length, IsParameter);
2002 // This is used by the flow code to hold the `layout' of the flow vector for
2003 // all locals and all parameters (ie. we create one instance of this class for the
2004 // locals and another one for the params).
2006 public class VariableMap {
2008 // The number of variables in the map.
2010 public readonly int Count;
2013 // Total length of the flow vector for this map.
2015 public readonly int Length;
2019 public VariableMap (InternalParameters ip)
2021 Count = ip != null ? ip.Count : 0;
2023 // Dont bother allocating anything!
2029 for (int i = 0; i < Count; i++) {
2030 Parameter.Modifier mod = ip.ParameterModifier (i);
2032 if ((mod & Parameter.Modifier.OUT) == 0)
2035 // Dont allocate till we find an out var.
2037 map = new VariableInfo [Count];
2039 map [i] = new VariableInfo (ip.ParameterName (i),
2040 TypeManager.GetElementType (ip.ParameterType (i)), i, Length);
2042 Length += map [i].Length;
2046 public VariableMap (LocalInfo[] locals)
2047 : this (null, locals)
2050 public VariableMap (VariableMap parent, LocalInfo[] locals)
2052 int offset = 0, start = 0;
2053 if (parent != null && parent.map != null) {
2054 offset = parent.Length;
2055 start = parent.Count;
2058 Count = locals.Length + start;
2063 map = new VariableInfo [Count];
2066 if (parent != null && parent.map != null) {
2067 parent.map.CopyTo (map, 0);
2070 for (int i = start; i < Count; i++) {
2071 LocalInfo li = locals [i-start];
2073 if (li.VariableType == null)
2076 map [i] = li.VariableInfo = new VariableInfo (li, Length);
2077 Length += map [i].Length;
2082 // Returns the VariableInfo for variable @index or null if we don't need to
2083 // compute assignment info for this variable.
2085 public VariableInfo this [int index] {
2094 public override string ToString ()
2096 return String.Format ("VariableMap ({0}:{1})", Count, Length);
2101 // This is a special bit vector which can inherit from another bit vector doing a
2102 // copy-on-write strategy. The inherited vector may have a smaller size than the
2105 public class MyBitVector {
2106 public readonly int Count;
2107 public readonly MyBitVector InheritsFrom;
2112 public MyBitVector (int Count)
2113 : this (null, Count)
2116 public MyBitVector (MyBitVector InheritsFrom, int Count)
2118 this.InheritsFrom = InheritsFrom;
2123 // Checks whether this bit vector has been modified. After setting this to true,
2124 // we won't use the inherited vector anymore, but our own copy of it.
2126 public bool IsDirty {
2133 initialize_vector ();
2138 // Get/set bit `index' in the bit vector.
2140 public bool this [int index]
2144 throw new ArgumentOutOfRangeException ();
2146 // We're doing a "copy-on-write" strategy here; as long
2147 // as nobody writes to the array, we can use our parent's
2148 // copy instead of duplicating the vector.
2151 return vector [index];
2152 else if (InheritsFrom != null) {
2153 BitArray inherited = InheritsFrom.Vector;
2155 if (index < inherited.Count)
2156 return inherited [index];
2165 throw new ArgumentOutOfRangeException ();
2167 // Only copy the vector if we're actually modifying it.
2169 if (this [index] != value) {
2170 initialize_vector ();
2172 vector [index] = value;
2178 // If you explicitly convert the MyBitVector to a BitArray, you will get a deep
2179 // copy of the bit vector.
2181 public static explicit operator BitArray (MyBitVector vector)
2183 vector.initialize_vector ();
2184 return vector.Vector;
2188 // Performs an `or' operation on the bit vector. The `new_vector' may have a
2189 // different size than the current one.
2191 public void Or (MyBitVector new_vector)
2193 BitArray new_array = new_vector.Vector;
2195 initialize_vector ();
2198 if (vector.Count < new_array.Count)
2199 upper = vector.Count;
2201 upper = new_array.Count;
2203 for (int i = 0; i < upper; i++)
2204 vector [i] = vector [i] | new_array [i];
2208 // Perfonrms an `and' operation on the bit vector. The `new_vector' may have
2209 // a different size than the current one.
2211 public void And (MyBitVector new_vector)
2213 BitArray new_array = new_vector.Vector;
2215 initialize_vector ();
2218 if (vector.Count < new_array.Count)
2219 lower = upper = vector.Count;
2221 lower = new_array.Count;
2222 upper = vector.Count;
2225 for (int i = 0; i < lower; i++)
2226 vector [i] = vector [i] & new_array [i];
2228 for (int i = lower; i < upper; i++)
2232 public static void And (ref MyBitVector target, MyBitVector vector)
2235 target.And (vector);
2237 target = vector.Clone ();
2240 public static void Or (ref MyBitVector target, MyBitVector vector)
2245 target = vector.Clone ();
2249 // This does a deep copy of the bit vector.
2251 public MyBitVector Clone ()
2253 MyBitVector retval = new MyBitVector (Count);
2255 retval.Vector = Vector;
2264 else if (!is_dirty && (InheritsFrom != null))
2265 return InheritsFrom.Vector;
2267 initialize_vector ();
2273 initialize_vector ();
2275 for (int i = 0; i < System.Math.Min (vector.Count, value.Count); i++)
2276 vector [i] = value [i];
2280 void initialize_vector ()
2285 vector = new BitArray (Count, false);
2286 if (InheritsFrom != null)
2287 Vector = InheritsFrom.Vector;
2292 public override string ToString ()
2294 StringBuilder sb = new StringBuilder ("{");
2296 BitArray vector = Vector;
2299 for (int i = 0; i < vector.Count; i++) {
2300 sb.Append (vector [i] ? "1" : "0");
2304 return sb.ToString ();