1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT LIBRARY COMPONENTS                          --
4--                                                                          --
5--           A D A . C O N T A I N E R S . H A S H E D _ S E T S            --
6--                                                                          --
7--                                 B o d y                                  --
8--                                                                          --
9--          Copyright (C) 2004-2019, Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- This unit was originally developed by Matthew J Heaney.                  --
28------------------------------------------------------------------------------
29
30with Ada.Unchecked_Deallocation;
31
32with Ada.Containers.Hash_Tables.Generic_Operations;
33pragma Elaborate_All (Ada.Containers.Hash_Tables.Generic_Operations);
34
35with Ada.Containers.Hash_Tables.Generic_Keys;
36pragma Elaborate_All (Ada.Containers.Hash_Tables.Generic_Keys);
37
38with Ada.Containers.Helpers; use Ada.Containers.Helpers;
39
40with Ada.Containers.Prime_Numbers;
41
42with System; use type System.Address;
43
44package body Ada.Containers.Hashed_Sets is
45
46   pragma Warnings (Off, "variable ""Busy*"" is not referenced");
47   pragma Warnings (Off, "variable ""Lock*"" is not referenced");
48   --  See comment in Ada.Containers.Helpers
49
50   -----------------------
51   -- Local Subprograms --
52   -----------------------
53
54   procedure Assign (Node : Node_Access; Item : Element_Type);
55   pragma Inline (Assign);
56
57   function Copy_Node (Source : Node_Access) return Node_Access;
58   pragma Inline (Copy_Node);
59
60   function Equivalent_Keys
61     (Key  : Element_Type;
62      Node : Node_Access) return Boolean;
63   pragma Inline (Equivalent_Keys);
64
65   function Find_Equal_Key
66     (R_HT   : Hash_Table_Type;
67      L_Node : Node_Access) return Boolean;
68
69   function Find_Equivalent_Key
70     (R_HT   : Hash_Table_Type;
71      L_Node : Node_Access) return Boolean;
72
73   procedure Free (X : in out Node_Access);
74
75   function Hash_Node (Node : Node_Access) return Hash_Type;
76   pragma Inline (Hash_Node);
77
78   procedure Insert
79     (HT       : in out Hash_Table_Type;
80      New_Item : Element_Type;
81      Node     : out Node_Access;
82      Inserted : out Boolean);
83
84   function Is_In
85     (HT  : aliased in out Hash_Table_Type;
86      Key : Node_Access) return Boolean;
87   pragma Inline (Is_In);
88
89   function Next (Node : Node_Access) return Node_Access;
90   pragma Inline (Next);
91
92   function Read_Node (Stream : not null access Root_Stream_Type'Class)
93     return Node_Access;
94   pragma Inline (Read_Node);
95
96   procedure Set_Next (Node : Node_Access; Next : Node_Access);
97   pragma Inline (Set_Next);
98
99   function Vet (Position : Cursor) return Boolean;
100
101   procedure Write_Node
102     (Stream : not null access Root_Stream_Type'Class;
103      Node   : Node_Access);
104   pragma Inline (Write_Node);
105
106   --------------------------
107   -- Local Instantiations --
108   --------------------------
109
110   package HT_Ops is new Hash_Tables.Generic_Operations
111     (HT_Types  => HT_Types,
112      Hash_Node => Hash_Node,
113      Next      => Next,
114      Set_Next  => Set_Next,
115      Copy_Node => Copy_Node,
116      Free      => Free);
117
118   package Element_Keys is new Hash_Tables.Generic_Keys
119     (HT_Types        => HT_Types,
120      Next            => Next,
121      Set_Next        => Set_Next,
122      Key_Type        => Element_Type,
123      Hash            => Hash,
124      Equivalent_Keys => Equivalent_Keys);
125
126   function Is_Equal is
127      new HT_Ops.Generic_Equal (Find_Equal_Key);
128
129   function Is_Equivalent is
130      new HT_Ops.Generic_Equal (Find_Equivalent_Key);
131
132   procedure Read_Nodes is
133      new HT_Ops.Generic_Read (Read_Node);
134
135   procedure Replace_Element is
136      new Element_Keys.Generic_Replace_Element (Hash_Node, Assign);
137
138   procedure Write_Nodes is
139      new HT_Ops.Generic_Write (Write_Node);
140
141   ---------
142   -- "=" --
143   ---------
144
145   function "=" (Left, Right : Set) return Boolean is
146   begin
147      return Is_Equal (Left.HT, Right.HT);
148   end "=";
149
150   ------------
151   -- Adjust --
152   ------------
153
154   procedure Adjust (Container : in out Set) is
155   begin
156      HT_Ops.Adjust (Container.HT);
157   end Adjust;
158
159   ------------
160   -- Assign --
161   ------------
162
163   procedure Assign (Node : Node_Access; Item : Element_Type) is
164   begin
165      Node.Element := Item;
166   end Assign;
167
168   procedure Assign (Target : in out Set; Source : Set) is
169   begin
170      if Target'Address = Source'Address then
171         return;
172      end if;
173
174      Target.Clear;
175      Target.Union (Source);
176   end Assign;
177
178   --------------
179   -- Capacity --
180   --------------
181
182   function Capacity (Container : Set) return Count_Type is
183   begin
184      return HT_Ops.Capacity (Container.HT);
185   end Capacity;
186
187   -----------
188   -- Clear --
189   -----------
190
191   procedure Clear (Container : in out Set) is
192   begin
193      HT_Ops.Clear (Container.HT);
194   end Clear;
195
196   ------------------------
197   -- Constant_Reference --
198   ------------------------
199
200   function Constant_Reference
201     (Container : aliased Set;
202      Position  : Cursor) return Constant_Reference_Type
203   is
204   begin
205      if Checks and then Position.Container = null then
206         raise Constraint_Error with "Position cursor has no element";
207      end if;
208
209      if Checks and then Position.Container /= Container'Unrestricted_Access
210      then
211         raise Program_Error with
212           "Position cursor designates wrong container";
213      end if;
214
215      pragma Assert (Vet (Position), "bad cursor in Constant_Reference");
216
217      declare
218         HT : Hash_Table_Type renames Position.Container.all.HT;
219         TC : constant Tamper_Counts_Access :=
220           HT.TC'Unrestricted_Access;
221      begin
222         return R : constant Constant_Reference_Type :=
223           (Element => Position.Node.Element'Access,
224            Control => (Controlled with TC))
225         do
226            Busy (TC.all);
227         end return;
228      end;
229   end Constant_Reference;
230
231   --------------
232   -- Contains --
233   --------------
234
235   function Contains (Container : Set; Item : Element_Type) return Boolean is
236   begin
237      return Find (Container, Item) /= No_Element;
238   end Contains;
239
240   ----------
241   -- Copy --
242   ----------
243
244   function Copy
245     (Source   : Set;
246      Capacity : Count_Type := 0) return Set
247   is
248      C : Count_Type;
249
250   begin
251      if Capacity < Source.Length then
252         if Checks and then Capacity /= 0 then
253            raise Capacity_Error
254              with "Requested capacity is less than Source length";
255         end if;
256
257         C := Source.Length;
258      else
259         C := Capacity;
260      end if;
261
262      return Target : Set do
263         Target.Reserve_Capacity (C);
264         Target.Assign (Source);
265      end return;
266   end Copy;
267
268   ---------------
269   -- Copy_Node --
270   ---------------
271
272   function Copy_Node (Source : Node_Access) return Node_Access is
273   begin
274      return new Node_Type'(Element => Source.Element, Next => null);
275   end Copy_Node;
276
277   ------------
278   -- Delete --
279   ------------
280
281   procedure Delete
282     (Container : in out Set;
283      Item      : Element_Type)
284   is
285      X : Node_Access;
286
287   begin
288      Element_Keys.Delete_Key_Sans_Free (Container.HT, Item, X);
289
290      if Checks and then X = null then
291         raise Constraint_Error with "attempt to delete element not in set";
292      end if;
293
294      Free (X);
295   end Delete;
296
297   procedure Delete
298     (Container : in out Set;
299      Position  : in out Cursor)
300   is
301   begin
302      if Checks and then Position.Node = null then
303         raise Constraint_Error with "Position cursor equals No_Element";
304      end if;
305
306      if Checks and then Position.Container /= Container'Unrestricted_Access
307      then
308         raise Program_Error with "Position cursor designates wrong set";
309      end if;
310
311      TC_Check (Container.HT.TC);
312
313      pragma Assert (Vet (Position), "bad cursor in Delete");
314
315      HT_Ops.Delete_Node_Sans_Free (Container.HT, Position.Node);
316
317      Free (Position.Node);
318      Position.Container := null;
319   end Delete;
320
321   ----------------
322   -- Difference --
323   ----------------
324
325   procedure Difference
326     (Target : in out Set;
327      Source : Set)
328   is
329      Tgt_Node : Node_Access;
330      Src_HT   : Hash_Table_Type renames Source'Unrestricted_Access.HT;
331
332   begin
333      if Target'Address = Source'Address then
334         Clear (Target);
335         return;
336      end if;
337
338      if Src_HT.Length = 0 then
339         return;
340      end if;
341
342      TC_Check (Target.HT.TC);
343
344      if Src_HT.Length < Target.HT.Length then
345         declare
346            Src_Node : Node_Access;
347
348         begin
349            Src_Node := HT_Ops.First (Src_HT);
350            while Src_Node /= null loop
351               Tgt_Node := Element_Keys.Find (Target.HT, Src_Node.Element);
352
353               if Tgt_Node /= null then
354                  HT_Ops.Delete_Node_Sans_Free (Target.HT, Tgt_Node);
355                  Free (Tgt_Node);
356               end if;
357
358               Src_Node := HT_Ops.Next (Src_HT, Src_Node);
359            end loop;
360         end;
361
362      else
363         Tgt_Node := HT_Ops.First (Target.HT);
364         while Tgt_Node /= null loop
365            if Is_In (Src_HT, Tgt_Node) then
366               declare
367                  X : Node_Access := Tgt_Node;
368               begin
369                  Tgt_Node := HT_Ops.Next (Target.HT, Tgt_Node);
370                  HT_Ops.Delete_Node_Sans_Free (Target.HT, X);
371                  Free (X);
372               end;
373
374            else
375               Tgt_Node := HT_Ops.Next (Target.HT, Tgt_Node);
376            end if;
377         end loop;
378      end if;
379   end Difference;
380
381   function Difference (Left, Right : Set) return Set is
382      Left_HT  : Hash_Table_Type renames Left'Unrestricted_Access.HT;
383      Right_HT : Hash_Table_Type renames Right'Unrestricted_Access.HT;
384      Buckets  : HT_Types.Buckets_Access;
385      Length   : Count_Type;
386
387   begin
388      if Left'Address = Right'Address then
389         return Empty_Set;
390      end if;
391
392      if Left_HT.Length = 0 then
393         return Empty_Set;
394      end if;
395
396      if Right_HT.Length = 0 then
397         return Left;
398      end if;
399
400      declare
401         Size : constant Hash_Type := Prime_Numbers.To_Prime (Left.Length);
402      begin
403         Buckets := HT_Ops.New_Buckets (Length => Size);
404      end;
405
406      Length := 0;
407
408      Iterate_Left : declare
409         procedure Process (L_Node : Node_Access);
410
411         procedure Iterate is
412            new HT_Ops.Generic_Iteration (Process);
413
414         -------------
415         -- Process --
416         -------------
417
418         procedure Process (L_Node : Node_Access) is
419         begin
420            if not Is_In (Right_HT, L_Node) then
421               declare
422                  --  Per AI05-0022, the container implementation is required
423                  --  to detect element tampering by a generic actual
424                  --  subprogram, hence the use of Checked_Index instead of a
425                  --  simple invocation of generic formal Hash.
426
427                  J : constant Hash_Type :=
428                    HT_Ops.Checked_Index (Left_HT, Buckets.all, L_Node);
429
430                  Bucket : Node_Access renames Buckets (J);
431
432               begin
433                  Bucket := new Node_Type'(L_Node.Element, Bucket);
434               end;
435
436               Length := Length + 1;
437            end if;
438         end Process;
439
440      --  Start of processing for Iterate_Left
441
442      begin
443         Iterate (Left_HT);
444      exception
445         when others =>
446            HT_Ops.Free_Hash_Table (Buckets);
447            raise;
448      end Iterate_Left;
449
450      return (Controlled with HT => (Buckets, Length, (Busy => 0, Lock => 0)));
451   end Difference;
452
453   -------------
454   -- Element --
455   -------------
456
457   function Element (Position : Cursor) return Element_Type is
458   begin
459      if Checks and then Position.Node = null then
460         raise Constraint_Error with "Position cursor equals No_Element";
461      end if;
462
463      pragma Assert (Vet (Position), "bad cursor in function Element");
464
465      return Position.Node.Element;
466   end Element;
467
468   ---------------------
469   -- Equivalent_Sets --
470   ---------------------
471
472   function Equivalent_Sets (Left, Right : Set) return Boolean is
473   begin
474      return Is_Equivalent (Left.HT, Right.HT);
475   end Equivalent_Sets;
476
477   -------------------------
478   -- Equivalent_Elements --
479   -------------------------
480
481   function Equivalent_Elements (Left, Right : Cursor)
482     return Boolean is
483   begin
484      if Checks and then Left.Node = null then
485         raise Constraint_Error with
486           "Left cursor of Equivalent_Elements equals No_Element";
487      end if;
488
489      if Checks and then Right.Node = null then
490         raise Constraint_Error with
491           "Right cursor of Equivalent_Elements equals No_Element";
492      end if;
493
494      pragma Assert (Vet (Left), "bad Left cursor in Equivalent_Elements");
495      pragma Assert (Vet (Right), "bad Right cursor in Equivalent_Elements");
496
497      --  AI05-0022 requires that a container implementation detect element
498      --  tampering by a generic actual subprogram. However, the following case
499      --  falls outside the scope of that AI. Randy Brukardt explained on the
500      --  ARG list on 2013/02/07 that:
501
502      --  (Begin Quote):
503      --  But for an operation like "<" [the ordered set analog of
504      --  Equivalent_Elements], there is no need to "dereference" a cursor
505      --  after the call to the generic formal parameter function, so nothing
506      --  bad could happen if tampering is undetected. And the operation can
507      --  safely return a result without a problem even if an element is
508      --  deleted from the container.
509      --  (End Quote).
510
511      return Equivalent_Elements (Left.Node.Element, Right.Node.Element);
512   end Equivalent_Elements;
513
514   function Equivalent_Elements (Left : Cursor; Right : Element_Type)
515     return Boolean is
516   begin
517      if Checks and then Left.Node = null then
518         raise Constraint_Error with
519           "Left cursor of Equivalent_Elements equals No_Element";
520      end if;
521
522      pragma Assert (Vet (Left), "Left cursor in Equivalent_Elements is bad");
523
524      return Equivalent_Elements (Left.Node.Element, Right);
525   end Equivalent_Elements;
526
527   function Equivalent_Elements (Left : Element_Type; Right : Cursor)
528     return Boolean is
529   begin
530      if Checks and then Right.Node = null then
531         raise Constraint_Error with
532           "Right cursor of Equivalent_Elements equals No_Element";
533      end if;
534
535      pragma Assert
536        (Vet (Right),
537         "Right cursor of Equivalent_Elements is bad");
538
539      return Equivalent_Elements (Left, Right.Node.Element);
540   end Equivalent_Elements;
541
542   ---------------------
543   -- Equivalent_Keys --
544   ---------------------
545
546   function Equivalent_Keys (Key : Element_Type; Node : Node_Access)
547     return Boolean is
548   begin
549      return Equivalent_Elements (Key, Node.Element);
550   end Equivalent_Keys;
551
552   -------------
553   -- Exclude --
554   -------------
555
556   procedure Exclude
557     (Container : in out Set;
558      Item      : Element_Type)
559   is
560      X : Node_Access;
561   begin
562      Element_Keys.Delete_Key_Sans_Free (Container.HT, Item, X);
563      Free (X);
564   end Exclude;
565
566   --------------
567   -- Finalize --
568   --------------
569
570   procedure Finalize (Container : in out Set) is
571   begin
572      HT_Ops.Finalize (Container.HT);
573   end Finalize;
574
575   procedure Finalize (Object : in out Iterator) is
576   begin
577      if Object.Container /= null then
578         Unbusy (Object.Container.HT.TC);
579      end if;
580   end Finalize;
581
582   ----------
583   -- Find --
584   ----------
585
586   function Find
587     (Container : Set;
588      Item      : Element_Type) return Cursor
589   is
590      HT   : Hash_Table_Type renames Container'Unrestricted_Access.HT;
591      Node : constant Node_Access := Element_Keys.Find (HT, Item);
592
593   begin
594      if Node = null then
595         return No_Element;
596      end if;
597
598      return Cursor'(Container'Unrestricted_Access, Node, Hash_Type'Last);
599   end Find;
600
601   --------------------
602   -- Find_Equal_Key --
603   --------------------
604
605   function Find_Equal_Key
606     (R_HT   : Hash_Table_Type;
607      L_Node : Node_Access) return Boolean
608   is
609      R_Index : constant Hash_Type :=
610        Element_Keys.Index (R_HT, L_Node.Element);
611
612      R_Node  : Node_Access := R_HT.Buckets (R_Index);
613
614   begin
615      loop
616         if R_Node = null then
617            return False;
618         end if;
619
620         if L_Node.Element = R_Node.Element then
621            return True;
622         end if;
623
624         R_Node := Next (R_Node);
625      end loop;
626   end Find_Equal_Key;
627
628   -------------------------
629   -- Find_Equivalent_Key --
630   -------------------------
631
632   function Find_Equivalent_Key
633     (R_HT   : Hash_Table_Type;
634      L_Node : Node_Access) return Boolean
635   is
636      R_Index : constant Hash_Type :=
637        Element_Keys.Index (R_HT, L_Node.Element);
638
639      R_Node  : Node_Access := R_HT.Buckets (R_Index);
640
641   begin
642      loop
643         if R_Node = null then
644            return False;
645         end if;
646
647         if Equivalent_Elements (L_Node.Element, R_Node.Element) then
648            return True;
649         end if;
650
651         R_Node := Next (R_Node);
652      end loop;
653   end Find_Equivalent_Key;
654
655   -----------
656   -- First --
657   -----------
658
659   function First (Container : Set) return Cursor is
660      Pos  : Hash_Type;
661      Node : constant Node_Access := HT_Ops.First (Container.HT, Pos);
662   begin
663      if Node = null then
664         return No_Element;
665      end if;
666
667      return Cursor'(Container'Unrestricted_Access, Node, Pos);
668   end First;
669
670   function First (Object : Iterator) return Cursor is
671   begin
672      return Object.Container.First;
673   end First;
674
675   ----------
676   -- Free --
677   ----------
678
679   procedure Free (X : in out Node_Access) is
680      procedure Deallocate is
681         new Ada.Unchecked_Deallocation (Node_Type, Node_Access);
682
683   begin
684      if X /= null then
685         X.Next := X;     --  detect mischief (in Vet)
686         Deallocate (X);
687      end if;
688   end Free;
689
690   ------------------------
691   -- Get_Element_Access --
692   ------------------------
693
694   function Get_Element_Access
695     (Position : Cursor) return not null Element_Access is
696   begin
697      return Position.Node.Element'Access;
698   end Get_Element_Access;
699
700   -----------------
701   -- Has_Element --
702   -----------------
703
704   function Has_Element (Position : Cursor) return Boolean is
705   begin
706      pragma Assert (Vet (Position), "bad cursor in Has_Element");
707      return Position.Node /= null;
708   end Has_Element;
709
710   ---------------
711   -- Hash_Node --
712   ---------------
713
714   function Hash_Node (Node : Node_Access) return Hash_Type is
715   begin
716      return Hash (Node.Element);
717   end Hash_Node;
718
719   -------------
720   -- Include --
721   -------------
722
723   procedure Include
724     (Container : in out Set;
725      New_Item  : Element_Type)
726   is
727      Position : Cursor;
728      Inserted : Boolean;
729
730   begin
731      Insert (Container, New_Item, Position, Inserted);
732
733      if not Inserted then
734         TE_Check (Container.HT.TC);
735
736         Position.Node.Element := New_Item;
737      end if;
738   end Include;
739
740   ------------
741   -- Insert --
742   ------------
743
744   procedure Insert
745     (Container : in out Set;
746      New_Item  : Element_Type;
747      Position  : out Cursor;
748      Inserted  : out Boolean)
749   is
750   begin
751      Insert (Container.HT, New_Item, Position.Node, Inserted);
752      Position.Container := Container'Unchecked_Access;
753   end Insert;
754
755   procedure Insert
756     (Container : in out Set;
757      New_Item  : Element_Type)
758   is
759      Position : Cursor;
760      pragma Unreferenced (Position);
761
762      Inserted : Boolean;
763
764   begin
765      Insert (Container, New_Item, Position, Inserted);
766
767      if Checks and then not Inserted then
768         raise Constraint_Error with
769           "attempt to insert element already in set";
770      end if;
771   end Insert;
772
773   procedure Insert
774     (HT       : in out Hash_Table_Type;
775      New_Item : Element_Type;
776      Node     : out Node_Access;
777      Inserted : out Boolean)
778   is
779      function New_Node (Next : Node_Access) return Node_Access;
780      pragma Inline (New_Node);
781
782      procedure Local_Insert is
783        new Element_Keys.Generic_Conditional_Insert (New_Node);
784
785      --------------
786      -- New_Node --
787      --------------
788
789      function New_Node (Next : Node_Access) return Node_Access is
790      begin
791         return new Node_Type'(New_Item, Next);
792      end New_Node;
793
794   --  Start of processing for Insert
795
796   begin
797      if HT_Ops.Capacity (HT) = 0 then
798         HT_Ops.Reserve_Capacity (HT, 1);
799      end if;
800
801      TC_Check (HT.TC);
802
803      Local_Insert (HT, New_Item, Node, Inserted);
804
805      if Inserted
806        and then HT.Length > HT_Ops.Capacity (HT)
807      then
808         HT_Ops.Reserve_Capacity (HT, HT.Length);
809      end if;
810   end Insert;
811
812   ------------------
813   -- Intersection --
814   ------------------
815
816   procedure Intersection
817     (Target : in out Set;
818      Source : Set)
819   is
820      Src_HT   : Hash_Table_Type renames Source'Unrestricted_Access.HT;
821      Tgt_Node : Node_Access;
822
823   begin
824      if Target'Address = Source'Address then
825         return;
826      end if;
827
828      if Source.HT.Length = 0 then
829         Clear (Target);
830         return;
831      end if;
832
833      TC_Check (Target.HT.TC);
834
835      Tgt_Node := HT_Ops.First (Target.HT);
836      while Tgt_Node /= null loop
837         if Is_In (Src_HT, Tgt_Node) then
838            Tgt_Node := HT_Ops.Next (Target.HT, Tgt_Node);
839
840         else
841            declare
842               X : Node_Access := Tgt_Node;
843            begin
844               Tgt_Node := HT_Ops.Next (Target.HT, Tgt_Node);
845               HT_Ops.Delete_Node_Sans_Free (Target.HT, X);
846               Free (X);
847            end;
848         end if;
849      end loop;
850   end Intersection;
851
852   function Intersection (Left, Right : Set) return Set is
853      Left_HT  : Hash_Table_Type renames Left'Unrestricted_Access.HT;
854      Right_HT : Hash_Table_Type renames Right'Unrestricted_Access.HT;
855      Buckets  : HT_Types.Buckets_Access;
856      Length   : Count_Type;
857
858   begin
859      if Left'Address = Right'Address then
860         return Left;
861      end if;
862
863      Length := Count_Type'Min (Left.Length, Right.Length);
864
865      if Length = 0 then
866         return Empty_Set;
867      end if;
868
869      declare
870         Size : constant Hash_Type := Prime_Numbers.To_Prime (Length);
871      begin
872         Buckets := HT_Ops.New_Buckets (Length => Size);
873      end;
874
875      Length := 0;
876
877      Iterate_Left : declare
878         procedure Process (L_Node : Node_Access);
879
880         procedure Iterate is
881            new HT_Ops.Generic_Iteration (Process);
882
883         -------------
884         -- Process --
885         -------------
886
887         procedure Process (L_Node : Node_Access) is
888         begin
889            if Is_In (Right_HT, L_Node) then
890               declare
891                  --  Per AI05-0022, the container implementation is required
892                  --  to detect element tampering by a generic actual
893                  --  subprogram, hence the use of Checked_Index instead of a
894                  --  simple invocation of generic formal Hash.
895
896                  J : constant Hash_Type :=
897                    HT_Ops.Checked_Index (Left_HT, Buckets.all, L_Node);
898
899                  Bucket : Node_Access renames Buckets (J);
900
901               begin
902                  Bucket := new Node_Type'(L_Node.Element, Bucket);
903               end;
904
905               Length := Length + 1;
906            end if;
907         end Process;
908
909      --  Start of processing for Iterate_Left
910
911      begin
912         Iterate (Left_HT);
913      exception
914         when others =>
915            HT_Ops.Free_Hash_Table (Buckets);
916            raise;
917      end Iterate_Left;
918
919      return (Controlled with HT => (Buckets, Length, (Busy => 0, Lock => 0)));
920   end Intersection;
921
922   --------------
923   -- Is_Empty --
924   --------------
925
926   function Is_Empty (Container : Set) return Boolean is
927   begin
928      return Container.HT.Length = 0;
929   end Is_Empty;
930
931   -----------
932   -- Is_In --
933   -----------
934
935   function Is_In
936     (HT : aliased in out Hash_Table_Type;
937      Key : Node_Access) return Boolean
938   is
939   begin
940      return Element_Keys.Find (HT, Key.Element) /= null;
941   end Is_In;
942
943   ---------------
944   -- Is_Subset --
945   ---------------
946
947   function Is_Subset (Subset : Set; Of_Set : Set) return Boolean is
948      Subset_HT   : Hash_Table_Type renames Subset'Unrestricted_Access.HT;
949      Of_Set_HT   : Hash_Table_Type renames Of_Set'Unrestricted_Access.HT;
950      Subset_Node : Node_Access;
951
952   begin
953      if Subset'Address = Of_Set'Address then
954         return True;
955      end if;
956
957      if Subset.Length > Of_Set.Length then
958         return False;
959      end if;
960
961      Subset_Node := HT_Ops.First (Subset_HT);
962      while Subset_Node /= null loop
963         if not Is_In (Of_Set_HT, Subset_Node) then
964            return False;
965         end if;
966         Subset_Node := HT_Ops.Next (Subset_HT, Subset_Node);
967      end loop;
968
969      return True;
970   end Is_Subset;
971
972   -------------
973   -- Iterate --
974   -------------
975
976   procedure Iterate
977     (Container : Set;
978      Process   : not null access procedure (Position : Cursor))
979   is
980      procedure Process_Node (Node : Node_Access; Position : Hash_Type);
981      pragma Inline (Process_Node);
982
983      procedure Iterate is
984        new HT_Ops.Generic_Iteration_With_Position (Process_Node);
985
986      ------------------
987      -- Process_Node --
988      ------------------
989
990      procedure Process_Node (Node : Node_Access; Position : Hash_Type) is
991      begin
992         Process (Cursor'(Container'Unrestricted_Access, Node, Position));
993      end Process_Node;
994
995      Busy : With_Busy (Container.HT.TC'Unrestricted_Access);
996
997   --  Start of processing for Iterate
998
999   begin
1000      Iterate (Container.HT);
1001   end Iterate;
1002
1003   function Iterate
1004     (Container : Set) return Set_Iterator_Interfaces.Forward_Iterator'Class
1005   is
1006   begin
1007      Busy (Container.HT.TC'Unrestricted_Access.all);
1008      return It : constant Iterator :=
1009         Iterator'(Limited_Controlled with
1010              Container => Container'Unrestricted_Access);
1011   end Iterate;
1012
1013   ------------
1014   -- Length --
1015   ------------
1016
1017   function Length (Container : Set) return Count_Type is
1018   begin
1019      return Container.HT.Length;
1020   end Length;
1021
1022   ----------
1023   -- Move --
1024   ----------
1025
1026   procedure Move (Target : in out Set; Source : in out Set) is
1027   begin
1028      HT_Ops.Move (Target => Target.HT, Source => Source.HT);
1029   end Move;
1030
1031   ----------
1032   -- Next --
1033   ----------
1034
1035   function Next (Node : Node_Access) return Node_Access is
1036   begin
1037      return Node.Next;
1038   end Next;
1039
1040   function Next (Position : Cursor) return Cursor is
1041      Node : Node_Access;
1042      Pos  : Hash_Type;
1043   begin
1044      if Position.Node = null then
1045         return No_Element;
1046      end if;
1047
1048      pragma Assert (Vet (Position), "bad cursor in Next");
1049
1050      Pos := Position.Position;
1051      Node := HT_Ops.Next (Position.Container.HT, Position.Node, Pos);
1052
1053      if Node = null then
1054         return No_Element;
1055      end if;
1056
1057      return Cursor'(Position.Container, Node, Pos);
1058   end Next;
1059
1060   procedure Next (Position : in out Cursor) is
1061   begin
1062      Position := Next (Position);
1063   end Next;
1064
1065   function Next
1066     (Object   : Iterator;
1067      Position : Cursor) return Cursor
1068   is
1069   begin
1070      if Position.Container = null then
1071         return No_Element;
1072      end if;
1073
1074      if Checks and then Position.Container /= Object.Container then
1075         raise Program_Error with
1076           "Position cursor of Next designates wrong set";
1077      end if;
1078
1079      return Next (Position);
1080   end Next;
1081
1082   -------------
1083   -- Overlap --
1084   -------------
1085
1086   function Overlap (Left, Right : Set) return Boolean is
1087      Left_HT   : Hash_Table_Type renames Left'Unrestricted_Access.HT;
1088      Right_HT  : Hash_Table_Type renames Right'Unrestricted_Access.HT;
1089      Left_Node : Node_Access;
1090
1091   begin
1092      if Right.Length = 0 then
1093         return False;
1094      end if;
1095
1096      if Left'Address = Right'Address then
1097         return True;
1098      end if;
1099
1100      Left_Node := HT_Ops.First (Left_HT);
1101      while Left_Node /= null loop
1102         if Is_In (Right_HT, Left_Node) then
1103            return True;
1104         end if;
1105         Left_Node := HT_Ops.Next (Left_HT, Left_Node);
1106      end loop;
1107
1108      return False;
1109   end Overlap;
1110
1111   ----------------------
1112   -- Pseudo_Reference --
1113   ----------------------
1114
1115   function Pseudo_Reference
1116     (Container : aliased Set'Class) return Reference_Control_Type
1117   is
1118      TC : constant Tamper_Counts_Access :=
1119        Container.HT.TC'Unrestricted_Access;
1120   begin
1121      return R : constant Reference_Control_Type := (Controlled with TC) do
1122         Busy (TC.all);
1123      end return;
1124   end Pseudo_Reference;
1125
1126   -------------------
1127   -- Query_Element --
1128   -------------------
1129
1130   procedure Query_Element
1131     (Position : Cursor;
1132      Process  : not null access procedure (Element : Element_Type))
1133   is
1134   begin
1135      if Checks and then Position.Node = null then
1136         raise Constraint_Error with
1137           "Position cursor of Query_Element equals No_Element";
1138      end if;
1139
1140      pragma Assert (Vet (Position), "bad cursor in Query_Element");
1141
1142      declare
1143         HT : Hash_Table_Type renames Position.Container.HT;
1144         Lock : With_Lock (HT.TC'Unrestricted_Access);
1145      begin
1146         Process (Position.Node.Element);
1147      end;
1148   end Query_Element;
1149
1150   ----------
1151   -- Read --
1152   ----------
1153
1154   procedure Read
1155     (Stream    : not null access Root_Stream_Type'Class;
1156      Container : out Set)
1157   is
1158   begin
1159      Read_Nodes (Stream, Container.HT);
1160   end Read;
1161
1162   procedure Read
1163     (Stream : not null access Root_Stream_Type'Class;
1164      Item   : out Cursor)
1165   is
1166   begin
1167      raise Program_Error with "attempt to stream set cursor";
1168   end Read;
1169
1170   procedure Read
1171     (Stream : not null access Root_Stream_Type'Class;
1172      Item   : out Constant_Reference_Type)
1173   is
1174   begin
1175      raise Program_Error with "attempt to stream reference";
1176   end Read;
1177
1178   ---------------
1179   -- Read_Node --
1180   ---------------
1181
1182   function Read_Node (Stream : not null access Root_Stream_Type'Class)
1183     return Node_Access
1184   is
1185      Node : Node_Access := new Node_Type;
1186   begin
1187      Element_Type'Read (Stream, Node.Element);
1188      return Node;
1189   exception
1190      when others =>
1191         Free (Node);
1192         raise;
1193   end Read_Node;
1194
1195   -------------
1196   -- Replace --
1197   -------------
1198
1199   procedure Replace
1200     (Container : in out Set;
1201      New_Item  : Element_Type)
1202   is
1203      Node : constant Node_Access :=
1204        Element_Keys.Find (Container.HT, New_Item);
1205
1206   begin
1207      if Checks and then Node = null then
1208         raise Constraint_Error with
1209           "attempt to replace element not in set";
1210      end if;
1211
1212      TE_Check (Container.HT.TC);
1213
1214      Node.Element := New_Item;
1215   end Replace;
1216
1217   procedure Replace_Element
1218     (Container : in out Set;
1219      Position  : Cursor;
1220      New_Item  : Element_Type)
1221   is
1222   begin
1223      if Checks and then Position.Node = null then
1224         raise Constraint_Error with
1225           "Position cursor equals No_Element";
1226      end if;
1227
1228      if Checks and then Position.Container /= Container'Unrestricted_Access
1229      then
1230         raise Program_Error with
1231           "Position cursor designates wrong set";
1232      end if;
1233
1234      pragma Assert (Vet (Position), "bad cursor in Replace_Element");
1235
1236      Replace_Element (Container.HT, Position.Node, New_Item);
1237   end Replace_Element;
1238
1239   ----------------------
1240   -- Reserve_Capacity --
1241   ----------------------
1242
1243   procedure Reserve_Capacity
1244     (Container : in out Set;
1245      Capacity  : Count_Type)
1246   is
1247   begin
1248      HT_Ops.Reserve_Capacity (Container.HT, Capacity);
1249   end Reserve_Capacity;
1250
1251   --------------
1252   -- Set_Next --
1253   --------------
1254
1255   procedure Set_Next (Node : Node_Access; Next : Node_Access) is
1256   begin
1257      Node.Next := Next;
1258   end Set_Next;
1259
1260   --------------------------
1261   -- Symmetric_Difference --
1262   --------------------------
1263
1264   procedure Symmetric_Difference
1265     (Target : in out Set;
1266      Source : Set)
1267   is
1268      Tgt_HT : Hash_Table_Type renames Target.HT;
1269      Src_HT : Hash_Table_Type renames Source.HT'Unrestricted_Access.all;
1270   begin
1271      if Target'Address = Source'Address then
1272         Clear (Target);
1273         return;
1274      end if;
1275
1276      TC_Check (Tgt_HT.TC);
1277
1278      declare
1279         N : constant Count_Type := Target.Length + Source.Length;
1280      begin
1281         if N > HT_Ops.Capacity (Tgt_HT) then
1282            HT_Ops.Reserve_Capacity (Tgt_HT, N);
1283         end if;
1284      end;
1285
1286      if Target.Length = 0 then
1287         Iterate_Source_When_Empty_Target : declare
1288            procedure Process (Src_Node : Node_Access);
1289
1290            procedure Iterate is new HT_Ops.Generic_Iteration (Process);
1291
1292            -------------
1293            -- Process --
1294            -------------
1295
1296            procedure Process (Src_Node : Node_Access) is
1297               E : Element_Type renames Src_Node.Element;
1298               B : Buckets_Type renames Tgt_HT.Buckets.all;
1299               J : constant Hash_Type := Hash (E) mod B'Length;
1300               N : Count_Type renames Tgt_HT.Length;
1301
1302            begin
1303               B (J) := new Node_Type'(E, B (J));
1304               N := N + 1;
1305            end Process;
1306
1307            --  Per AI05-0022, the container implementation is required to
1308            --  detect element tampering by a generic actual subprogram.
1309
1310            Lock_Tgt : With_Lock (Tgt_HT.TC'Unrestricted_Access);
1311            Lock_Src : With_Lock (Src_HT.TC'Unrestricted_Access);
1312
1313         --  Start of processing for Iterate_Source_When_Empty_Target
1314
1315         begin
1316            Iterate (Src_HT);
1317         end Iterate_Source_When_Empty_Target;
1318
1319      else
1320         Iterate_Source : declare
1321            procedure Process (Src_Node : Node_Access);
1322
1323            procedure Iterate is
1324               new HT_Ops.Generic_Iteration (Process);
1325
1326            -------------
1327            -- Process --
1328            -------------
1329
1330            procedure Process (Src_Node : Node_Access) is
1331               E : Element_Type renames Src_Node.Element;
1332               B : Buckets_Type renames Tgt_HT.Buckets.all;
1333               J : constant Hash_Type := Hash (E) mod B'Length;
1334               N : Count_Type renames Tgt_HT.Length;
1335
1336            begin
1337               if B (J) = null then
1338                  B (J) := new Node_Type'(E, null);
1339                  N := N + 1;
1340
1341               elsif Equivalent_Elements (E, B (J).Element) then
1342                  declare
1343                     X : Node_Access := B (J);
1344                  begin
1345                     B (J) := B (J).Next;
1346                     N := N - 1;
1347                     Free (X);
1348                  end;
1349
1350               else
1351                  declare
1352                     Prev : Node_Access := B (J);
1353                     Curr : Node_Access := Prev.Next;
1354
1355                  begin
1356                     while Curr /= null loop
1357                        if Equivalent_Elements (E, Curr.Element) then
1358                           Prev.Next := Curr.Next;
1359                           N := N - 1;
1360                           Free (Curr);
1361                           return;
1362                        end if;
1363
1364                        Prev := Curr;
1365                        Curr := Prev.Next;
1366                     end loop;
1367
1368                     B (J) := new Node_Type'(E, B (J));
1369                     N := N + 1;
1370                  end;
1371               end if;
1372            end Process;
1373
1374            --  Per AI05-0022, the container implementation is required to
1375            --  detect element tampering by a generic actual subprogram.
1376
1377            Lock_Tgt : With_Lock (Tgt_HT.TC'Unrestricted_Access);
1378            Lock_Src : With_Lock (Src_HT.TC'Unrestricted_Access);
1379
1380         --  Start of processing for Iterate_Source
1381
1382         begin
1383            Iterate (Src_HT);
1384         end Iterate_Source;
1385      end if;
1386   end Symmetric_Difference;
1387
1388   function Symmetric_Difference (Left, Right : Set) return Set is
1389      Left_HT  : Hash_Table_Type renames Left'Unrestricted_Access.HT;
1390      Right_HT : Hash_Table_Type renames Right'Unrestricted_Access.HT;
1391      Buckets  : HT_Types.Buckets_Access;
1392      Length   : Count_Type;
1393
1394   begin
1395      if Left'Address = Right'Address then
1396         return Empty_Set;
1397      end if;
1398
1399      if Right.Length = 0 then
1400         return Left;
1401      end if;
1402
1403      if Left.Length = 0 then
1404         return Right;
1405      end if;
1406
1407      declare
1408         Size : constant Hash_Type :=
1409           Prime_Numbers.To_Prime (Left.Length + Right.Length);
1410      begin
1411         Buckets := HT_Ops.New_Buckets (Length => Size);
1412      end;
1413
1414      Length := 0;
1415
1416      Iterate_Left : declare
1417         procedure Process (L_Node : Node_Access);
1418
1419         procedure Iterate is
1420            new HT_Ops.Generic_Iteration (Process);
1421
1422         -------------
1423         -- Process --
1424         -------------
1425
1426         procedure Process (L_Node : Node_Access) is
1427         begin
1428            if not Is_In (Right_HT, L_Node) then
1429               declare
1430                  E : Element_Type renames L_Node.Element;
1431
1432                  --  Per AI05-0022, the container implementation is required
1433                  --  to detect element tampering by a generic actual
1434                  --  subprogram, hence the use of Checked_Index instead of a
1435                  --  simple invocation of generic formal Hash.
1436
1437                  J : constant Hash_Type :=
1438                    HT_Ops.Checked_Index (Left_HT, Buckets.all, L_Node);
1439
1440               begin
1441                  Buckets (J) := new Node_Type'(E, Buckets (J));
1442                  Length := Length + 1;
1443               end;
1444            end if;
1445         end Process;
1446
1447      --  Start of processing for Iterate_Left
1448
1449      begin
1450         Iterate (Left_HT);
1451
1452      exception
1453         when others =>
1454            HT_Ops.Free_Hash_Table (Buckets);
1455            raise;
1456      end Iterate_Left;
1457
1458      Iterate_Right : declare
1459         procedure Process (R_Node : Node_Access);
1460
1461         procedure Iterate is
1462            new HT_Ops.Generic_Iteration (Process);
1463
1464         -------------
1465         -- Process --
1466         -------------
1467
1468         procedure Process (R_Node : Node_Access) is
1469         begin
1470            if not Is_In (Left_HT, R_Node) then
1471               declare
1472                  E : Element_Type renames R_Node.Element;
1473
1474                  --  Per AI05-0022, the container implementation is required
1475                  --  to detect element tampering by a generic actual
1476                  --  subprogram, hence the use of Checked_Index instead of a
1477                  --  simple invocation of generic formal Hash.
1478
1479                  J : constant Hash_Type :=
1480                    HT_Ops.Checked_Index (Right_HT, Buckets.all, R_Node);
1481
1482               begin
1483                  Buckets (J) := new Node_Type'(E, Buckets (J));
1484                  Length := Length + 1;
1485               end;
1486            end if;
1487         end Process;
1488
1489      --  Start of processing for Iterate_Right
1490
1491      begin
1492         Iterate (Right_HT);
1493
1494      exception
1495         when others =>
1496            HT_Ops.Free_Hash_Table (Buckets);
1497            raise;
1498      end Iterate_Right;
1499
1500      return (Controlled with HT => (Buckets, Length, (Busy => 0, Lock => 0)));
1501   end Symmetric_Difference;
1502
1503   ------------
1504   -- To_Set --
1505   ------------
1506
1507   function To_Set (New_Item : Element_Type) return Set is
1508      HT : Hash_Table_Type;
1509
1510      Node     : Node_Access;
1511      Inserted : Boolean;
1512      pragma Unreferenced (Node, Inserted);
1513
1514   begin
1515      Insert (HT, New_Item, Node, Inserted);
1516      return Set'(Controlled with HT);
1517   end To_Set;
1518
1519   -----------
1520   -- Union --
1521   -----------
1522
1523   procedure Union
1524     (Target : in out Set;
1525      Source : Set)
1526   is
1527      procedure Process (Src_Node : Node_Access);
1528
1529      procedure Iterate is
1530         new HT_Ops.Generic_Iteration (Process);
1531
1532      -------------
1533      -- Process --
1534      -------------
1535
1536      procedure Process (Src_Node : Node_Access) is
1537         function New_Node (Next : Node_Access) return Node_Access;
1538         pragma Inline (New_Node);
1539
1540         procedure Insert is
1541            new Element_Keys.Generic_Conditional_Insert (New_Node);
1542
1543         --------------
1544         -- New_Node --
1545         --------------
1546
1547         function New_Node (Next : Node_Access) return Node_Access is
1548            Node : constant Node_Access :=
1549              new Node_Type'(Src_Node.Element, Next);
1550         begin
1551            return Node;
1552         end New_Node;
1553
1554         Tgt_Node : Node_Access;
1555         Success  : Boolean;
1556         pragma Unreferenced (Tgt_Node, Success);
1557
1558      --  Start of processing for Process
1559
1560      begin
1561         Insert (Target.HT, Src_Node.Element, Tgt_Node, Success);
1562      end Process;
1563
1564   --  Start of processing for Union
1565
1566   begin
1567      if Target'Address = Source'Address then
1568         return;
1569      end if;
1570
1571      TC_Check (Target.HT.TC);
1572
1573      declare
1574         N : constant Count_Type := Target.Length + Source.Length;
1575      begin
1576         if N > HT_Ops.Capacity (Target.HT) then
1577            HT_Ops.Reserve_Capacity (Target.HT, N);
1578         end if;
1579      end;
1580
1581      Iterate (Source.HT);
1582   end Union;
1583
1584   function Union (Left, Right : Set) return Set is
1585      Left_HT  : Hash_Table_Type renames Left.HT'Unrestricted_Access.all;
1586      Right_HT : Hash_Table_Type renames Right.HT'Unrestricted_Access.all;
1587      Buckets  : HT_Types.Buckets_Access;
1588      Length   : Count_Type;
1589
1590   begin
1591      if Left'Address = Right'Address then
1592         return Left;
1593      end if;
1594
1595      if Right.Length = 0 then
1596         return Left;
1597      end if;
1598
1599      if Left.Length = 0 then
1600         return Right;
1601      end if;
1602
1603      declare
1604         Size : constant Hash_Type :=
1605           Prime_Numbers.To_Prime (Left.Length + Right.Length);
1606      begin
1607         Buckets := HT_Ops.New_Buckets (Length => Size);
1608      end;
1609
1610      Iterate_Left : declare
1611         procedure Process (L_Node : Node_Access);
1612
1613         procedure Iterate is
1614            new HT_Ops.Generic_Iteration (Process);
1615
1616         -------------
1617         -- Process --
1618         -------------
1619
1620         procedure Process (L_Node : Node_Access) is
1621            J : constant Hash_Type :=
1622              Hash (L_Node.Element) mod Buckets'Length;
1623
1624         begin
1625            Buckets (J) := new Node_Type'(L_Node.Element, Buckets (J));
1626         end Process;
1627
1628         --  Per AI05-0022, the container implementation is required to detect
1629         --  element tampering by a generic actual subprogram, hence the use of
1630         --  Checked_Index instead of a simple invocation of generic formal
1631         --  Hash.
1632
1633         Lock_Left : With_Lock (Left_HT.TC'Unrestricted_Access);
1634
1635      --  Start of processing for Iterate_Left
1636
1637      begin
1638         Iterate (Left_HT);
1639      exception
1640         when others =>
1641            HT_Ops.Free_Hash_Table (Buckets);
1642            raise;
1643      end Iterate_Left;
1644
1645      Length := Left.Length;
1646
1647      Iterate_Right : declare
1648         procedure Process (Src_Node : Node_Access);
1649
1650         procedure Iterate is
1651            new HT_Ops.Generic_Iteration (Process);
1652
1653         -------------
1654         -- Process --
1655         -------------
1656
1657         procedure Process (Src_Node : Node_Access) is
1658            J : constant Hash_Type :=
1659              Hash (Src_Node.Element) mod Buckets'Length;
1660
1661            Tgt_Node : Node_Access := Buckets (J);
1662
1663         begin
1664            while Tgt_Node /= null loop
1665               if Equivalent_Elements (Src_Node.Element, Tgt_Node.Element) then
1666                  return;
1667               end if;
1668
1669               Tgt_Node := Next (Tgt_Node);
1670            end loop;
1671
1672            Buckets (J) := new Node_Type'(Src_Node.Element, Buckets (J));
1673            Length := Length + 1;
1674         end Process;
1675
1676         --  Per AI05-0022, the container implementation is required to detect
1677         --  element tampering by a generic actual subprogram, hence the use of
1678         --  Checked_Index instead of a simple invocation of generic formal
1679         --  Hash.
1680
1681         Lock_Left : With_Lock (Left_HT.TC'Unrestricted_Access);
1682         Lock_Right : With_Lock (Right_HT.TC'Unrestricted_Access);
1683
1684      --  Start of processing for Iterate_Right
1685
1686      begin
1687         Iterate (Right_HT);
1688      exception
1689         when others =>
1690            HT_Ops.Free_Hash_Table (Buckets);
1691            raise;
1692      end Iterate_Right;
1693
1694      return (Controlled with HT => (Buckets, Length, (Busy => 0, Lock => 0)));
1695   end Union;
1696
1697   ---------
1698   -- Vet --
1699   ---------
1700
1701   function Vet (Position : Cursor) return Boolean is
1702   begin
1703      if Position.Node = null then
1704         return Position.Container = null;
1705      end if;
1706
1707      if Position.Container = null then
1708         return False;
1709      end if;
1710
1711      if Position.Node.Next = Position.Node then
1712         return False;
1713      end if;
1714
1715      declare
1716         HT : Hash_Table_Type renames Position.Container.HT;
1717         X  : Node_Access;
1718
1719      begin
1720         if HT.Length = 0 then
1721            return False;
1722         end if;
1723
1724         if HT.Buckets = null
1725           or else HT.Buckets'Length = 0
1726         then
1727            return False;
1728         end if;
1729
1730         X := HT.Buckets (Element_Keys.Checked_Index
1731                            (HT,
1732                             Position.Node.Element));
1733
1734         for J in 1 .. HT.Length loop
1735            if X = Position.Node then
1736               return True;
1737            end if;
1738
1739            if X = null then
1740               return False;
1741            end if;
1742
1743            if X = X.Next then  --  to prevent unnecessary looping
1744               return False;
1745            end if;
1746
1747            X := X.Next;
1748         end loop;
1749
1750         return False;
1751      end;
1752   end Vet;
1753
1754   -----------
1755   -- Write --
1756   -----------
1757
1758   procedure Write
1759     (Stream    : not null access Root_Stream_Type'Class;
1760      Container : Set)
1761   is
1762   begin
1763      Write_Nodes (Stream, Container.HT);
1764   end Write;
1765
1766   procedure Write
1767     (Stream : not null access Root_Stream_Type'Class;
1768      Item   : Cursor)
1769   is
1770   begin
1771      raise Program_Error with "attempt to stream set cursor";
1772   end Write;
1773
1774   procedure Write
1775     (Stream : not null access Root_Stream_Type'Class;
1776      Item   : Constant_Reference_Type)
1777   is
1778   begin
1779      raise Program_Error with "attempt to stream reference";
1780   end Write;
1781
1782   ----------------
1783   -- Write_Node --
1784   ----------------
1785
1786   procedure Write_Node
1787     (Stream : not null access Root_Stream_Type'Class;
1788      Node   : Node_Access)
1789   is
1790   begin
1791      Element_Type'Write (Stream, Node.Element);
1792   end Write_Node;
1793
1794   package body Generic_Keys is
1795
1796      -----------------------
1797      -- Local Subprograms --
1798      -----------------------
1799
1800      function Equivalent_Key_Node
1801        (Key  : Key_Type;
1802         Node : Node_Access) return Boolean;
1803      pragma Inline (Equivalent_Key_Node);
1804
1805      --------------------------
1806      -- Local Instantiations --
1807      --------------------------
1808
1809      package Key_Keys is
1810         new Hash_Tables.Generic_Keys
1811          (HT_Types  => HT_Types,
1812           Next      => Next,
1813           Set_Next  => Set_Next,
1814           Key_Type  => Key_Type,
1815           Hash      => Hash,
1816           Equivalent_Keys => Equivalent_Key_Node);
1817
1818      ------------------------
1819      -- Constant_Reference --
1820      ------------------------
1821
1822      function Constant_Reference
1823        (Container : aliased Set;
1824         Key       : Key_Type) return Constant_Reference_Type
1825      is
1826         HT   : Hash_Table_Type renames Container'Unrestricted_Access.HT;
1827         Node : constant Node_Access := Key_Keys.Find (HT, Key);
1828
1829      begin
1830         if Checks and then Node = null then
1831            raise Constraint_Error with "Key not in set";
1832         end if;
1833
1834         declare
1835            TC : constant Tamper_Counts_Access :=
1836              HT.TC'Unrestricted_Access;
1837         begin
1838            return R : constant Constant_Reference_Type :=
1839              (Element => Node.Element'Access,
1840               Control => (Controlled with TC))
1841            do
1842               Busy (TC.all);
1843            end return;
1844         end;
1845      end Constant_Reference;
1846
1847      --------------
1848      -- Contains --
1849      --------------
1850
1851      function Contains
1852        (Container : Set;
1853         Key       : Key_Type) return Boolean
1854      is
1855      begin
1856         return Find (Container, Key) /= No_Element;
1857      end Contains;
1858
1859      ------------
1860      -- Delete --
1861      ------------
1862
1863      procedure Delete
1864        (Container : in out Set;
1865         Key       : Key_Type)
1866      is
1867         X : Node_Access;
1868
1869      begin
1870         Key_Keys.Delete_Key_Sans_Free (Container.HT, Key, X);
1871
1872         if Checks and then X = null then
1873            raise Constraint_Error with "attempt to delete key not in set";
1874         end if;
1875
1876         Free (X);
1877      end Delete;
1878
1879      -------------
1880      -- Element --
1881      -------------
1882
1883      function Element
1884        (Container : Set;
1885         Key       : Key_Type) return Element_Type
1886      is
1887         HT   : Hash_Table_Type renames Container'Unrestricted_Access.HT;
1888         Node : constant Node_Access := Key_Keys.Find (HT, Key);
1889
1890      begin
1891         if Checks and then Node = null then
1892            raise Constraint_Error with "key not in set";
1893         end if;
1894
1895         return Node.Element;
1896      end Element;
1897
1898      -------------------------
1899      -- Equivalent_Key_Node --
1900      -------------------------
1901
1902      function Equivalent_Key_Node
1903        (Key  : Key_Type;
1904         Node : Node_Access) return Boolean
1905      is
1906      begin
1907         return Equivalent_Keys (Key, Generic_Keys.Key (Node.Element));
1908      end Equivalent_Key_Node;
1909
1910      -------------
1911      -- Exclude --
1912      -------------
1913
1914      procedure Exclude
1915        (Container : in out Set;
1916         Key       : Key_Type)
1917      is
1918         X : Node_Access;
1919      begin
1920         Key_Keys.Delete_Key_Sans_Free (Container.HT, Key, X);
1921         Free (X);
1922      end Exclude;
1923
1924      --------------
1925      -- Finalize --
1926      --------------
1927
1928      procedure Finalize (Control : in out Reference_Control_Type) is
1929      begin
1930         if Control.Container /= null then
1931            Impl.Reference_Control_Type (Control).Finalize;
1932
1933            if Checks and then
1934              Hash (Key (Element (Control.Old_Pos))) /= Control.Old_Hash
1935            then
1936               HT_Ops.Delete_Node_At_Index
1937                 (Control.Container.HT, Control.Index, Control.Old_Pos.Node);
1938               raise Program_Error with "key not preserved in reference";
1939            end if;
1940
1941            Control.Container := null;
1942         end if;
1943      end Finalize;
1944
1945      ----------
1946      -- Find --
1947      ----------
1948
1949      function Find
1950        (Container : Set;
1951         Key       : Key_Type) return Cursor
1952      is
1953         HT   : Hash_Table_Type renames Container'Unrestricted_Access.HT;
1954         Node : constant Node_Access := Key_Keys.Find (HT, Key);
1955      begin
1956         if Node = null then
1957            return No_Element;
1958         else
1959            return Cursor'
1960              (Container'Unrestricted_Access, Node, Hash_Type'Last);
1961         end if;
1962      end Find;
1963
1964      ---------
1965      -- Key --
1966      ---------
1967
1968      function Key (Position : Cursor) return Key_Type is
1969      begin
1970         if Checks and then Position.Node = null then
1971            raise Constraint_Error with
1972              "Position cursor equals No_Element";
1973         end if;
1974
1975         pragma Assert (Vet (Position), "bad cursor in function Key");
1976
1977         return Key (Position.Node.Element);
1978      end Key;
1979
1980      ----------
1981      -- Read --
1982      ----------
1983
1984      procedure Read
1985        (Stream : not null access Root_Stream_Type'Class;
1986         Item   : out Reference_Type)
1987      is
1988      begin
1989         raise Program_Error with "attempt to stream reference";
1990      end Read;
1991
1992      ------------------------------
1993      -- Reference_Preserving_Key --
1994      ------------------------------
1995
1996      function Reference_Preserving_Key
1997        (Container : aliased in out Set;
1998         Position  : Cursor) return Reference_Type
1999      is
2000      begin
2001         if Checks and then Position.Container = null then
2002            raise Constraint_Error with "Position cursor has no element";
2003         end if;
2004
2005         if Checks and then Position.Container /= Container'Unrestricted_Access
2006         then
2007            raise Program_Error with
2008              "Position cursor designates wrong container";
2009         end if;
2010
2011         pragma Assert
2012           (Vet (Position),
2013            "bad cursor in function Reference_Preserving_Key");
2014
2015         declare
2016            HT : Hash_Table_Type renames Position.Container.all.HT;
2017         begin
2018            return R : constant Reference_Type :=
2019                         (Element => Position.Node.Element'Access,
2020                          Control =>
2021                            (Controlled with
2022                              HT.TC'Unrestricted_Access,
2023                              Container'Unrestricted_Access,
2024                              Index    => HT_Ops.Index (HT, Position.Node),
2025                              Old_Pos  => Position,
2026                              Old_Hash => Hash (Key (Position))))
2027            do
2028               Busy (HT.TC);
2029            end return;
2030         end;
2031      end Reference_Preserving_Key;
2032
2033      function Reference_Preserving_Key
2034        (Container : aliased in out Set;
2035         Key       : Key_Type) return Reference_Type
2036      is
2037         Node : constant Node_Access := Key_Keys.Find (Container.HT, Key);
2038
2039      begin
2040         if Checks and then Node = null then
2041            raise Constraint_Error with "key not in set";
2042         end if;
2043
2044         declare
2045            HT : Hash_Table_Type renames Container.HT;
2046            P  : constant Cursor := Find (Container, Key);
2047         begin
2048            return R : constant Reference_Type :=
2049                         (Element => Node.Element'Access,
2050                          Control =>
2051                            (Controlled with
2052                              HT.TC'Unrestricted_Access,
2053                              Container'Unrestricted_Access,
2054                              Index    => HT_Ops.Index (HT, P.Node),
2055                              Old_Pos  => P,
2056                              Old_Hash => Hash (Key)))
2057            do
2058               Busy (HT.TC);
2059            end return;
2060         end;
2061      end Reference_Preserving_Key;
2062
2063      -------------
2064      -- Replace --
2065      -------------
2066
2067      procedure Replace
2068        (Container : in out Set;
2069         Key       : Key_Type;
2070         New_Item  : Element_Type)
2071      is
2072         Node : constant Node_Access := Key_Keys.Find (Container.HT, Key);
2073
2074      begin
2075         if Checks and then Node = null then
2076            raise Constraint_Error with
2077              "attempt to replace key not in set";
2078         end if;
2079
2080         Replace_Element (Container.HT, Node, New_Item);
2081      end Replace;
2082
2083      -----------------------------------
2084      -- Update_Element_Preserving_Key --
2085      -----------------------------------
2086
2087      procedure Update_Element_Preserving_Key
2088        (Container : in out Set;
2089         Position  : Cursor;
2090         Process   : not null access
2091                       procedure (Element : in out Element_Type))
2092      is
2093         HT   : Hash_Table_Type renames Container.HT;
2094         Indx : Hash_Type;
2095
2096      begin
2097         if Checks and then Position.Node = null then
2098            raise Constraint_Error with
2099              "Position cursor equals No_Element";
2100         end if;
2101
2102         if Checks and then Position.Container /= Container'Unrestricted_Access
2103         then
2104            raise Program_Error with
2105              "Position cursor designates wrong set";
2106         end if;
2107
2108         if Checks and then
2109           (HT.Buckets = null
2110              or else HT.Buckets'Length = 0
2111              or else HT.Length = 0
2112              or else Position.Node.Next = Position.Node)
2113         then
2114            raise Program_Error with "Position cursor is bad (set is empty)";
2115         end if;
2116
2117         pragma Assert
2118           (Vet (Position),
2119            "bad cursor in Update_Element_Preserving_Key");
2120
2121         --  Per AI05-0022, the container implementation is required to detect
2122         --  element tampering by a generic actual subprogram.
2123
2124         declare
2125            E : Element_Type renames Position.Node.Element;
2126            K : constant Key_Type := Key (E);
2127            Lock : With_Lock (HT.TC'Unrestricted_Access);
2128         begin
2129            Indx := HT_Ops.Index (HT, Position.Node);
2130            Process (E);
2131
2132            if Equivalent_Keys (K, Key (E)) then
2133               return;
2134            end if;
2135         end;
2136
2137         if HT.Buckets (Indx) = Position.Node then
2138            HT.Buckets (Indx) := Position.Node.Next;
2139
2140         else
2141            declare
2142               Prev : Node_Access := HT.Buckets (Indx);
2143
2144            begin
2145               while Prev.Next /= Position.Node loop
2146                  Prev := Prev.Next;
2147
2148                  if Checks and then Prev = null then
2149                     raise Program_Error with
2150                       "Position cursor is bad (node not found)";
2151                  end if;
2152               end loop;
2153
2154               Prev.Next := Position.Node.Next;
2155            end;
2156         end if;
2157
2158         HT.Length := HT.Length - 1;
2159
2160         declare
2161            X : Node_Access := Position.Node;
2162
2163         begin
2164            Free (X);
2165         end;
2166
2167         raise Program_Error with "key was modified";
2168      end Update_Element_Preserving_Key;
2169
2170      -----------
2171      -- Write --
2172      -----------
2173
2174      procedure Write
2175        (Stream : not null access Root_Stream_Type'Class;
2176         Item   : Reference_Type)
2177      is
2178      begin
2179         raise Program_Error with "attempt to stream reference";
2180      end Write;
2181
2182   end Generic_Keys;
2183
2184end Ada.Containers.Hashed_Sets;
2185