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1 706 jeremybenn
------------------------------------------------------------------------------
2
--                                                                          --
3
--                         GNAT LIBRARY COMPONENTS                          --
4
--                                                                          --
5
--                 ADA.CONTAINERS.FORMAL_DOUBLY_LINKED_LISTS                --
6
--                                                                          --
7
--                                 B o d y                                  --
8
--                                                                          --
9
--          Copyright (C) 2010-2011, 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
 
28
with System;  use type System.Address;
29
with Ada.Finalization;
30
 
31
package body Ada.Containers.Formal_Doubly_Linked_Lists is
32
 
33
   type Iterator is new Ada.Finalization.Limited_Controlled and
34
     List_Iterator_Interfaces.Reversible_Iterator with
35
   record
36
      Container : List_Access;
37
      Node      : Count_Type;
38
   end record;
39
 
40
   overriding procedure Finalize (Object : in out Iterator);
41
 
42
   overriding function First (Object : Iterator) return Cursor;
43
   overriding function Last  (Object : Iterator) return Cursor;
44
 
45
   overriding function Next
46
     (Object   : Iterator;
47
      Position : Cursor) return Cursor;
48
 
49
   overriding function Previous
50
     (Object   : Iterator;
51
      Position : Cursor) return Cursor;
52
 
53
   -----------------------
54
   -- Local Subprograms --
55
   -----------------------
56
 
57
   procedure Allocate
58
     (Container : in out List;
59
      New_Item  : Element_Type;
60
      New_Node  : out Count_Type);
61
 
62
   procedure Allocate
63
     (Container : in out List;
64
      New_Node  : out Count_Type);
65
 
66
   procedure Free
67
     (Container : in out List;
68
      X         : Count_Type);
69
 
70
   procedure Insert_Internal
71
     (Container : in out List;
72
      Before    : Count_Type;
73
      New_Node  : Count_Type);
74
 
75
   function Vet (L : List; Position : Cursor) return Boolean;
76
 
77
   ---------
78
   -- "=" --
79
   ---------
80
 
81
   function "=" (Left, Right : List) return Boolean is
82
      LI, RI : Count_Type;
83
 
84
   begin
85
      if Left'Address = Right'Address then
86
         return True;
87
      end if;
88
 
89
      if Left.Length /= Right.Length then
90
         return False;
91
      end if;
92
 
93
      LI := Left.First;
94
      RI := Left.First;
95
      while LI /= 0 loop
96
         if Left.Nodes (LI).Element /= Right.Nodes (LI).Element then
97
            return False;
98
         end if;
99
 
100
         LI := Left.Nodes (LI).Next;
101
         RI := Right.Nodes (RI).Next;
102
      end loop;
103
 
104
      return True;
105
   end "=";
106
 
107
   --------------
108
   -- Allocate --
109
   --------------
110
 
111
   procedure Allocate
112
     (Container : in out List;
113
      New_Item  : Element_Type;
114
      New_Node  : out Count_Type)
115
   is
116
      N : Node_Array renames Container.Nodes;
117
 
118
   begin
119
      if Container.Free >= 0 then
120
         New_Node := Container.Free;
121
         N (New_Node).Element := New_Item;
122
         Container.Free := N (New_Node).Next;
123
 
124
      else
125
         New_Node := abs Container.Free;
126
         N (New_Node).Element := New_Item;
127
         Container.Free := Container.Free - 1;
128
      end if;
129
   end Allocate;
130
 
131
   procedure Allocate
132
     (Container : in out List;
133
      New_Node  : out Count_Type)
134
   is
135
      N : Node_Array renames Container.Nodes;
136
 
137
   begin
138
      if Container.Free >= 0 then
139
         New_Node := Container.Free;
140
         Container.Free := N (New_Node).Next;
141
 
142
      else
143
         New_Node := abs Container.Free;
144
         Container.Free := Container.Free - 1;
145
      end if;
146
   end Allocate;
147
 
148
   ------------
149
   -- Append --
150
   ------------
151
 
152
   procedure Append
153
     (Container : in out List;
154
      New_Item  : Element_Type;
155
      Count     : Count_Type := 1)
156
   is
157
   begin
158
      Insert (Container, No_Element, New_Item, Count);
159
   end Append;
160
 
161
   ------------
162
   -- Assign --
163
   ------------
164
 
165
   procedure Assign (Target : in out List; Source : List) is
166
      N : Node_Array renames Source.Nodes;
167
      J : Count_Type;
168
 
169
   begin
170
      if Target'Address = Source'Address then
171
         return;
172
      end if;
173
 
174
      if Target.Capacity < Source.Length then
175
         raise Constraint_Error with  -- ???
176
           "Source length exceeds Target capacity";
177
      end if;
178
 
179
      Clear (Target);
180
 
181
      J := Source.First;
182
      while J /= 0 loop
183
         Append (Target, N (J).Element);
184
         J := N (J).Next;
185
      end loop;
186
   end Assign;
187
 
188
   -----------
189
   -- Clear --
190
   -----------
191
 
192
   procedure Clear (Container : in out List) is
193
      N : Node_Array renames Container.Nodes;
194
      X : Count_Type;
195
 
196
   begin
197
      if Container.Length = 0 then
198
         pragma Assert (Container.First = 0);
199
         pragma Assert (Container.Last = 0);
200
         pragma Assert (Container.Busy = 0);
201
         pragma Assert (Container.Lock = 0);
202
         return;
203
      end if;
204
 
205
      pragma Assert (Container.First >= 1);
206
      pragma Assert (Container.Last >= 1);
207
      pragma Assert (N (Container.First).Prev = 0);
208
      pragma Assert (N (Container.Last).Next = 0);
209
 
210
      if Container.Busy > 0 then
211
         raise Program_Error with
212
           "attempt to tamper with elements (list is busy)";
213
      end if;
214
 
215
      while Container.Length > 1 loop
216
         X := Container.First;
217
 
218
         Container.First := N (X).Next;
219
         N (Container.First).Prev := 0;
220
 
221
         Container.Length := Container.Length - 1;
222
 
223
         Free (Container, X);
224
      end loop;
225
 
226
      X := Container.First;
227
 
228
      Container.First := 0;
229
      Container.Last := 0;
230
      Container.Length := 0;
231
 
232
      Free (Container, X);
233
   end Clear;
234
 
235
   --------------
236
   -- Contains --
237
   --------------
238
 
239
   function Contains
240
     (Container : List;
241
      Item      : Element_Type) return Boolean
242
   is
243
   begin
244
      return Find (Container, Item) /= No_Element;
245
   end Contains;
246
 
247
   ----------
248
   -- Copy --
249
   ----------
250
 
251
   function Copy
252
     (Source   : List;
253
      Capacity : Count_Type := 0) return List
254
   is
255
      C : constant Count_Type := Count_Type'Max (Source.Capacity, Capacity);
256
      N : Count_Type;
257
      P : List (C);
258
 
259
   begin
260
      N := 1;
261
      while N <= Source.Capacity loop
262
         P.Nodes (N).Prev := Source.Nodes (N).Prev;
263
         P.Nodes (N).Next := Source.Nodes (N).Next;
264
         P.Nodes (N).Element := Source.Nodes (N).Element;
265
         N := N + 1;
266
      end loop;
267
 
268
      P.Free := Source.Free;
269
      P.Length := Source.Length;
270
      P.First := Source.First;
271
      P.Last := Source.Last;
272
 
273
      if P.Free >= 0 then
274
         N := Source.Capacity + 1;
275
         while N <= C loop
276
            Free (P, N);
277
            N := N + 1;
278
         end loop;
279
      end if;
280
 
281
      return P;
282
   end Copy;
283
 
284
   ------------
285
   -- Delete --
286
   ------------
287
 
288
   procedure Delete
289
     (Container : in out List;
290
      Position  : in out Cursor;
291
      Count     : Count_Type := 1)
292
   is
293
      N : Node_Array renames Container.Nodes;
294
      X : Count_Type;
295
 
296
   begin
297
      if not Has_Element (Container => Container,
298
                          Position  => Position)
299
      then
300
         raise Constraint_Error with
301
           "Position cursor has no element";
302
      end if;
303
 
304
      pragma Assert (Vet (Container, Position), "bad cursor in Delete");
305
      pragma Assert (Container.First >= 1);
306
      pragma Assert (Container.Last >= 1);
307
      pragma Assert (N (Container.First).Prev = 0);
308
      pragma Assert (N (Container.Last).Next = 0);
309
 
310
      if Position.Node = Container.First then
311
         Delete_First (Container, Count);
312
         Position := No_Element;
313
         return;
314
      end if;
315
 
316
      if Count = 0 then
317
         Position := No_Element;
318
         return;
319
      end if;
320
 
321
      if Container.Busy > 0 then
322
         raise Program_Error with
323
           "attempt to tamper with elements (list is busy)";
324
      end if;
325
 
326
      for Index in 1 .. Count loop
327
         pragma Assert (Container.Length >= 2);
328
 
329
         X := Position.Node;
330
         Container.Length := Container.Length - 1;
331
 
332
         if X = Container.Last then
333
            Position := No_Element;
334
 
335
            Container.Last := N (X).Prev;
336
            N (Container.Last).Next := 0;
337
 
338
            Free (Container, X);
339
            return;
340
         end if;
341
 
342
         Position.Node := N (X).Next;
343
         pragma Assert (N (Position.Node).Prev >= 0);
344
 
345
         N (N (X).Next).Prev := N (X).Prev;
346
         N (N (X).Prev).Next := N (X).Next;
347
 
348
         Free (Container, X);
349
      end loop;
350
      Position := No_Element;
351
   end Delete;
352
 
353
   ------------------
354
   -- Delete_First --
355
   ------------------
356
 
357
   procedure Delete_First
358
     (Container : in out List;
359
      Count     : Count_Type := 1)
360
   is
361
      N : Node_Array renames Container.Nodes;
362
      X : Count_Type;
363
 
364
   begin
365
      if Count >= Container.Length then
366
         Clear (Container);
367
         return;
368
      end if;
369
 
370
      if Count = 0 then
371
         return;
372
      end if;
373
 
374
      if Container.Busy > 0 then
375
         raise Program_Error with
376
           "attempt to tamper with elements (list is busy)";
377
      end if;
378
 
379
      for J in 1 .. Count loop
380
         X := Container.First;
381
         pragma Assert (N (N (X).Next).Prev = Container.First);
382
 
383
         Container.First := N (X).Next;
384
         N (Container.First).Prev := 0;
385
 
386
         Container.Length := Container.Length - 1;
387
 
388
         Free (Container, X);
389
      end loop;
390
   end Delete_First;
391
 
392
   -----------------
393
   -- Delete_Last --
394
   -----------------
395
 
396
   procedure Delete_Last
397
     (Container : in out List;
398
      Count     : Count_Type := 1)
399
   is
400
      N : Node_Array renames Container.Nodes;
401
      X : Count_Type;
402
 
403
   begin
404
      if Count >= Container.Length then
405
         Clear (Container);
406
         return;
407
      end if;
408
 
409
      if Count = 0 then
410
         return;
411
      end if;
412
 
413
      if Container.Busy > 0 then
414
         raise Program_Error with
415
           "attempt to tamper with elements (list is busy)";
416
      end if;
417
 
418
      for J in 1 .. Count loop
419
         X := Container.Last;
420
         pragma Assert (N (N (X).Prev).Next = Container.Last);
421
 
422
         Container.Last := N (X).Prev;
423
         N (Container.Last).Next := 0;
424
 
425
         Container.Length := Container.Length - 1;
426
 
427
         Free (Container, X);
428
      end loop;
429
   end Delete_Last;
430
 
431
   -------------
432
   -- Element --
433
   -------------
434
 
435
   function Element
436
     (Container : List;
437
      Position  : Cursor) return Element_Type
438
   is
439
   begin
440
      if not Has_Element (Container => Container, Position  => Position) then
441
         raise Constraint_Error with
442
           "Position cursor has no element";
443
      end if;
444
 
445
      return Container.Nodes (Position.Node).Element;
446
   end Element;
447
 
448
   --------------
449
   -- Finalize --
450
   --------------
451
 
452
   procedure Finalize (Object : in out Iterator) is
453
   begin
454
      if Object.Container /= null then
455
         declare
456
            B : Natural renames Object.Container.all.Busy;
457
         begin
458
            B := B - 1;
459
         end;
460
      end if;
461
   end Finalize;
462
 
463
   ----------
464
   -- Find --
465
   ----------
466
 
467
   function Find
468
     (Container : List;
469
      Item      : Element_Type;
470
      Position  : Cursor := No_Element) return Cursor
471
   is
472
      From : Count_Type := Position.Node;
473
 
474
   begin
475
      if From = 0 and Container.Length = 0 then
476
         return No_Element;
477
      end if;
478
 
479
      if From = 0 then
480
         From := Container.First;
481
      end if;
482
 
483
      if Position.Node /= 0 and then
484
        not Has_Element (Container, Position)
485
      then
486
         raise Constraint_Error with
487
           "Position cursor has no element";
488
      end if;
489
 
490
      while From /= 0 loop
491
         if Container.Nodes (From).Element = Item then
492
            return (Node => From);
493
         end if;
494
 
495
         From := Container.Nodes (From).Next;
496
      end loop;
497
 
498
      return No_Element;
499
   end Find;
500
 
501
   -----------
502
   -- First --
503
   -----------
504
 
505
   function First (Container : List) return Cursor is
506
   begin
507
      if Container.First = 0 then
508
         return No_Element;
509
      end if;
510
 
511
      return (Node => Container.First);
512
   end First;
513
 
514
   function First (Object : Iterator) return Cursor is
515
   begin
516
      --  The value of the iterator object's Node component influences the
517
      --  behavior of the First (and Last) selector function.
518
 
519
      --  When the Node component is null, this means the iterator object was
520
      --  constructed without a start expression, in which case the (forward)
521
      --  iteration starts from the (logical) beginning of the entire sequence
522
      --  of items (corresponding to Container.First, for a forward iterator).
523
 
524
      --  Otherwise, this is iteration over a partial sequence of items. When
525
      --  the Node component is non-null, the iterator object was constructed
526
      --  with a start expression, that specifies the position from which the
527
      --  (forward) partial iteration begins.
528
 
529
      if Object.Node = 0 then
530
         return First (Object.Container.all);
531
      else
532
         return (Node => Object.Node);
533
      end if;
534
   end First;
535
 
536
   -------------------
537
   -- First_Element --
538
   -------------------
539
 
540
   function First_Element (Container : List) return Element_Type is
541
      F : constant Count_Type := Container.First;
542
   begin
543
      if F = 0 then
544
         raise Constraint_Error with "list is empty";
545
      else
546
         return Container.Nodes (F).Element;
547
      end if;
548
   end First_Element;
549
 
550
   ----------
551
   -- Free --
552
   ----------
553
 
554
   procedure Free
555
     (Container : in out List;
556
      X         : Count_Type)
557
   is
558
      pragma Assert (X > 0);
559
      pragma Assert (X <= Container.Capacity);
560
 
561
      N : Node_Array renames Container.Nodes;
562
 
563
   begin
564
      N (X).Prev := -1;  -- Node is deallocated (not on active list)
565
 
566
      if Container.Free >= 0 then
567
         N (X).Next := Container.Free;
568
         Container.Free := X;
569
 
570
      elsif X + 1 = abs Container.Free then
571
         N (X).Next := 0;  -- Not strictly necessary, but marginally safer
572
         Container.Free := Container.Free + 1;
573
 
574
      else
575
         Container.Free := abs Container.Free;
576
 
577
         if Container.Free > Container.Capacity then
578
            Container.Free := 0;
579
 
580
         else
581
            for J in Container.Free .. Container.Capacity - 1 loop
582
               N (J).Next := J + 1;
583
            end loop;
584
 
585
            N (Container.Capacity).Next := 0;
586
         end if;
587
 
588
         N (X).Next := Container.Free;
589
         Container.Free := X;
590
      end if;
591
   end Free;
592
 
593
   ---------------------
594
   -- Generic_Sorting --
595
   ---------------------
596
 
597
   package body Generic_Sorting is
598
 
599
      ---------------
600
      -- Is_Sorted --
601
      ---------------
602
 
603
      function Is_Sorted (Container : List) return Boolean is
604
         Nodes : Node_Array renames Container.Nodes;
605
         Node  : Count_Type := Container.First;
606
 
607
      begin
608
         for J in 2 .. Container.Length loop
609
            if Nodes (Nodes (Node).Next).Element < Nodes (Node).Element then
610
               return False;
611
            else
612
               Node := Nodes (Node).Next;
613
            end if;
614
         end loop;
615
 
616
         return True;
617
      end Is_Sorted;
618
 
619
      -----------
620
      -- Merge --
621
      -----------
622
 
623
      procedure Merge
624
        (Target : in out List;
625
         Source : in out List)
626
      is
627
         LN : Node_Array renames Target.Nodes;
628
         RN : Node_Array renames Source.Nodes;
629
         LI : Cursor;
630
         RI : Cursor;
631
 
632
      begin
633
         if Target'Address = Source'Address then
634
            return;
635
         end if;
636
 
637
         if Target.Busy > 0 then
638
            raise Program_Error with
639
              "attempt to tamper with cursors of Target (list is busy)";
640
         end if;
641
 
642
         if Source.Busy > 0 then
643
            raise Program_Error with
644
              "attempt to tamper with cursors of Source (list is busy)";
645
         end if;
646
 
647
         LI := First (Target);
648
         RI := First (Source);
649
         while RI.Node /= 0 loop
650
            pragma Assert (RN (RI.Node).Next = 0
651
              or else not (RN (RN (RI.Node).Next).Element <
652
                  RN (RI.Node).Element));
653
 
654
            if LI.Node = 0 then
655
               Splice (Target, No_Element, Source);
656
               return;
657
            end if;
658
 
659
            pragma Assert (LN (LI.Node).Next = 0
660
              or else not (LN (LN (LI.Node).Next).Element <
661
                  LN (LI.Node).Element));
662
 
663
            if RN (RI.Node).Element < LN (LI.Node).Element then
664
               declare
665
                  RJ : Cursor := RI;
666
                  pragma Warnings (Off, RJ);
667
               begin
668
                  RI.Node := RN (RI.Node).Next;
669
                  Splice (Target, LI, Source, RJ);
670
               end;
671
 
672
            else
673
               LI.Node := LN (LI.Node).Next;
674
            end if;
675
         end loop;
676
      end Merge;
677
 
678
      ----------
679
      -- Sort --
680
      ----------
681
 
682
      procedure Sort (Container : in out List) is
683
         N : Node_Array renames Container.Nodes;
684
 
685
         procedure Partition (Pivot, Back : Count_Type);
686
         procedure Sort (Front, Back : Count_Type);
687
 
688
         ---------------
689
         -- Partition --
690
         ---------------
691
 
692
         procedure Partition (Pivot, Back : Count_Type) is
693
            Node : Count_Type;
694
 
695
         begin
696
            Node := N (Pivot).Next;
697
            while Node /= Back loop
698
               if N (Node).Element < N (Pivot).Element then
699
                  declare
700
                     Prev : constant Count_Type := N (Node).Prev;
701
                     Next : constant Count_Type := N (Node).Next;
702
 
703
                  begin
704
                     N (Prev).Next := Next;
705
 
706
                     if Next = 0 then
707
                        Container.Last := Prev;
708
                     else
709
                        N (Next).Prev := Prev;
710
                     end if;
711
 
712
                     N (Node).Next := Pivot;
713
                     N (Node).Prev := N (Pivot).Prev;
714
 
715
                     N (Pivot).Prev := Node;
716
 
717
                     if N (Node).Prev = 0 then
718
                        Container.First := Node;
719
                     else
720
                        N (N (Node).Prev).Next := Node;
721
                     end if;
722
 
723
                     Node := Next;
724
                  end;
725
 
726
               else
727
                  Node := N (Node).Next;
728
               end if;
729
            end loop;
730
         end Partition;
731
 
732
         ----------
733
         -- Sort --
734
         ----------
735
 
736
         procedure Sort (Front, Back : Count_Type) is
737
            Pivot : Count_Type;
738
 
739
         begin
740
            if Front = 0 then
741
               Pivot := Container.First;
742
            else
743
               Pivot := N (Front).Next;
744
            end if;
745
 
746
            if Pivot /= Back then
747
               Partition (Pivot, Back);
748
               Sort (Front, Pivot);
749
               Sort (Pivot, Back);
750
            end if;
751
         end Sort;
752
 
753
      --  Start of processing for Sort
754
 
755
      begin
756
         if Container.Length <= 1 then
757
            return;
758
         end if;
759
 
760
         pragma Assert (N (Container.First).Prev = 0);
761
         pragma Assert (N (Container.Last).Next = 0);
762
 
763
         if Container.Busy > 0 then
764
            raise Program_Error with
765
              "attempt to tamper with elements (list is busy)";
766
         end if;
767
 
768
         Sort (Front => 0, Back => 0);
769
 
770
         pragma Assert (N (Container.First).Prev = 0);
771
         pragma Assert (N (Container.Last).Next = 0);
772
      end Sort;
773
 
774
   end Generic_Sorting;
775
 
776
   -----------------
777
   -- Has_Element --
778
   -----------------
779
 
780
   function Has_Element (Container : List; Position : Cursor) return Boolean is
781
   begin
782
      if Position.Node = 0 then
783
         return False;
784
      end if;
785
 
786
      return Container.Nodes (Position.Node).Prev /= -1;
787
   end Has_Element;
788
 
789
   ------------
790
   -- Insert --
791
   ------------
792
 
793
   procedure Insert
794
     (Container : in out List;
795
      Before    : Cursor;
796
      New_Item  : Element_Type;
797
      Position  : out Cursor;
798
      Count     : Count_Type := 1)
799
   is
800
      J : Count_Type;
801
 
802
   begin
803
      if Before.Node /= 0 then
804
         pragma Assert (Vet (Container, Before), "bad cursor in Insert");
805
      end if;
806
 
807
      if Count = 0 then
808
         Position := Before;
809
         return;
810
      end if;
811
 
812
      if Container.Length > Container.Capacity - Count then
813
         raise Constraint_Error with "new length exceeds capacity";
814
      end if;
815
 
816
      if Container.Busy > 0 then
817
         raise Program_Error with
818
           "attempt to tamper with elements (list is busy)";
819
      end if;
820
 
821
      Allocate (Container, New_Item, New_Node => J);
822
      Insert_Internal (Container, Before.Node, New_Node => J);
823
      Position := (Node => J);
824
 
825
      for Index in 2 .. Count loop
826
         Allocate (Container, New_Item, New_Node => J);
827
         Insert_Internal (Container, Before.Node, New_Node => J);
828
      end loop;
829
   end Insert;
830
 
831
   procedure Insert
832
     (Container : in out List;
833
      Before    : Cursor;
834
      New_Item  : Element_Type;
835
      Count     : Count_Type := 1)
836
   is
837
      Position : Cursor;
838
   begin
839
      Insert (Container, Before, New_Item, Position, Count);
840
   end Insert;
841
 
842
   procedure Insert
843
     (Container : in out List;
844
      Before    : Cursor;
845
      Position  : out Cursor;
846
      Count     : Count_Type := 1)
847
   is
848
      J : Count_Type;
849
 
850
   begin
851
      if Before.Node /= 0 then
852
         pragma Assert (Vet (Container, Before), "bad cursor in Insert");
853
      end if;
854
 
855
      if Count = 0 then
856
         Position := Before;
857
         return;
858
      end if;
859
 
860
      if Container.Length > Container.Capacity - Count then
861
         raise Constraint_Error with "new length exceeds capacity";
862
      end if;
863
 
864
      if Container.Busy > 0 then
865
         raise Program_Error with
866
           "attempt to tamper with elements (list is busy)";
867
      end if;
868
 
869
      Allocate (Container, New_Node => J);
870
      Insert_Internal (Container, Before.Node, New_Node => J);
871
      Position := (Node => J);
872
 
873
      for Index in 2 .. Count loop
874
         Allocate (Container, New_Node => J);
875
         Insert_Internal (Container, Before.Node, New_Node => J);
876
      end loop;
877
   end Insert;
878
 
879
   ---------------------
880
   -- Insert_Internal --
881
   ---------------------
882
 
883
   procedure Insert_Internal
884
     (Container : in out List;
885
      Before    : Count_Type;
886
      New_Node  : Count_Type)
887
   is
888
      N : Node_Array renames Container.Nodes;
889
 
890
   begin
891
      if Container.Length = 0 then
892
         pragma Assert (Before = 0);
893
         pragma Assert (Container.First = 0);
894
         pragma Assert (Container.Last = 0);
895
 
896
         Container.First := New_Node;
897
         Container.Last := New_Node;
898
 
899
         N (Container.First).Prev := 0;
900
         N (Container.Last).Next := 0;
901
 
902
      elsif Before = 0 then
903
         pragma Assert (N (Container.Last).Next = 0);
904
 
905
         N (Container.Last).Next := New_Node;
906
         N (New_Node).Prev := Container.Last;
907
 
908
         Container.Last := New_Node;
909
         N (Container.Last).Next := 0;
910
 
911
      elsif Before = Container.First then
912
         pragma Assert (N (Container.First).Prev = 0);
913
 
914
         N (Container.First).Prev := New_Node;
915
         N (New_Node).Next := Container.First;
916
 
917
         Container.First := New_Node;
918
         N (Container.First).Prev := 0;
919
 
920
      else
921
         pragma Assert (N (Container.First).Prev = 0);
922
         pragma Assert (N (Container.Last).Next = 0);
923
 
924
         N (New_Node).Next := Before;
925
         N (New_Node).Prev := N (Before).Prev;
926
 
927
         N (N (Before).Prev).Next := New_Node;
928
         N (Before).Prev := New_Node;
929
      end if;
930
 
931
      Container.Length := Container.Length + 1;
932
   end Insert_Internal;
933
 
934
   --------------
935
   -- Is_Empty --
936
   --------------
937
 
938
   function Is_Empty (Container : List) return Boolean is
939
   begin
940
      return Length (Container) = 0;
941
   end Is_Empty;
942
 
943
   -------------
944
   -- Iterate --
945
   -------------
946
 
947
   procedure Iterate
948
     (Container : List;
949
      Process   :
950
      not null access procedure (Container : List; Position : Cursor))
951
   is
952
      C    : List renames Container'Unrestricted_Access.all;
953
      B    : Natural renames C.Busy;
954
      Node : Count_Type;
955
 
956
   begin
957
      B := B + 1;
958
 
959
      begin
960
         Node := Container.First;
961
         while Node /= 0 loop
962
            Process (Container, (Node => Node));
963
            Node := Container.Nodes (Node).Next;
964
         end loop;
965
 
966
      exception
967
         when others =>
968
            B := B - 1;
969
            raise;
970
      end;
971
 
972
      B := B - 1;
973
   end Iterate;
974
 
975
   function Iterate (Container : List)
976
     return List_Iterator_Interfaces.Reversible_Iterator'Class
977
   is
978
      B : Natural renames Container'Unrestricted_Access.all.Busy;
979
 
980
   begin
981
      --  The value of the Node component influences the behavior of the First
982
      --  and Last selector functions of the iterator object. When the Node
983
      --  component is null (as is the case here), this means the iterator
984
      --  object was constructed without a start expression. This is a
985
      --  complete iterator, meaning that the iteration starts from the
986
      --  (logical) beginning of the sequence of items.
987
 
988
      --  Note: For a forward iterator, Container.First is the beginning, and
989
      --  for a reverse iterator, Container.Last is the beginning.
990
 
991
      return It : constant Iterator :=
992
                    Iterator'(Ada.Finalization.Limited_Controlled with
993
                                Container => Container'Unrestricted_Access,
994
                                Node      => 0)
995
      do
996
         B := B + 1;
997
      end return;
998
   end Iterate;
999
 
1000
   function Iterate (Container : List; Start : Cursor)
1001
     return List_Iterator_Interfaces.Reversible_Iterator'Class
1002
   is
1003
      B  : Natural renames Container'Unrestricted_Access.all.Busy;
1004
 
1005
   begin
1006
      --  It was formerly the case that when Start = No_Element, the partial
1007
      --  iterator was defined to behave the same as for a complete iterator,
1008
      --  and iterate over the entire sequence of items. However, those
1009
      --  semantics were unintuitive and arguably error-prone (it is too easy
1010
      --  to accidentally create an endless loop), and so they were changed,
1011
      --  per the ARG meeting in Denver on 2011/11. However, there was no
1012
      --  consensus about what positive meaning this corner case should have,
1013
      --  and so it was decided to simply raise an exception. This does imply,
1014
      --  however, that it is not possible to use a partial iterator to specify
1015
      --  an empty sequence of items.
1016
 
1017
      if not Has_Element (Container, Start) then
1018
         raise Constraint_Error with
1019
           "Start position for iterator is not a valid cursor";
1020
      end if;
1021
 
1022
      --  The value of the Node component influences the behavior of the First
1023
      --  and Last selector functions of the iterator object. When the Node
1024
      --  component is non-null (as is the case here), it means that this
1025
      --  is a partial iteration, over a subset of the complete sequence of
1026
      --  items. The iterator object was constructed with a start expression,
1027
      --  indicating the position from which the iteration begins. Note that
1028
      --  the start position has the same value irrespective of whether this
1029
      --  is a forward or reverse iteration.
1030
 
1031
      return It : constant Iterator :=
1032
                    Iterator'(Ada.Finalization.Limited_Controlled with
1033
                                Container => Container'Unrestricted_Access,
1034
                                Node      => Start.Node)
1035
      do
1036
         B := B + 1;
1037
      end return;
1038
   end Iterate;
1039
 
1040
   ----------
1041
   -- Last --
1042
   ----------
1043
 
1044
   function Last (Container : List) return Cursor is
1045
   begin
1046
      if Container.Last = 0 then
1047
         return No_Element;
1048
      end if;
1049
      return (Node => Container.Last);
1050
   end Last;
1051
 
1052
   function Last (Object : Iterator) return Cursor is
1053
   begin
1054
      --  The value of the iterator object's Node component influences the
1055
      --  behavior of the Last (and First) selector function.
1056
 
1057
      --  When the Node component is null, this means the iterator object was
1058
      --  constructed without a start expression, in which case the (reverse)
1059
      --  iteration starts from the (logical) beginning of the entire sequence
1060
      --  (corresponding to Container.Last, for a reverse iterator).
1061
 
1062
      --  Otherwise, this is iteration over a partial sequence of items. When
1063
      --  the Node component is non-null, the iterator object was constructed
1064
      --  with a start expression, that specifies the position from which the
1065
      --  (reverse) partial iteration begins.
1066
 
1067
      if Object.Node = 0 then
1068
         return Last (Object.Container.all);
1069
      else
1070
         return (Node => Object.Node);
1071
      end if;
1072
   end Last;
1073
 
1074
   ------------------
1075
   -- Last_Element --
1076
   ------------------
1077
 
1078
   function Last_Element (Container : List) return Element_Type is
1079
      L : constant Count_Type := Container.Last;
1080
   begin
1081
      if L = 0 then
1082
         raise Constraint_Error with "list is empty";
1083
      else
1084
         return Container.Nodes (L).Element;
1085
      end if;
1086
   end Last_Element;
1087
 
1088
   ----------
1089
   -- Left --
1090
   ----------
1091
 
1092
   function Left (Container : List; Position : Cursor) return List is
1093
      Curs : Cursor := Position;
1094
      C    : List (Container.Capacity) := Copy (Container, Container.Capacity);
1095
      Node : Count_Type;
1096
 
1097
   begin
1098
      if Curs = No_Element then
1099
         return C;
1100
      end if;
1101
 
1102
      if not Has_Element (Container, Curs) then
1103
         raise Constraint_Error;
1104
      end if;
1105
 
1106
      while Curs.Node /= 0 loop
1107
         Node := Curs.Node;
1108
         Delete (C, Curs);
1109
         Curs := Next (Container, (Node => Node));
1110
      end loop;
1111
 
1112
      return C;
1113
   end Left;
1114
 
1115
   ------------
1116
   -- Length --
1117
   ------------
1118
 
1119
   function Length (Container : List) return Count_Type is
1120
   begin
1121
      return Container.Length;
1122
   end Length;
1123
 
1124
   ----------
1125
   -- Move --
1126
   ----------
1127
 
1128
   procedure Move
1129
     (Target : in out List;
1130
      Source : in out List)
1131
   is
1132
      N : Node_Array renames Source.Nodes;
1133
      X : Count_Type;
1134
 
1135
   begin
1136
      if Target'Address = Source'Address then
1137
         return;
1138
      end if;
1139
 
1140
      if Target.Capacity < Source.Length then
1141
         raise Constraint_Error with  -- ???
1142
           "Source length exceeds Target capacity";
1143
      end if;
1144
 
1145
      if Source.Busy > 0 then
1146
         raise Program_Error with
1147
           "attempt to tamper with cursors of Source (list is busy)";
1148
      end if;
1149
 
1150
      Clear (Target);
1151
 
1152
      while Source.Length > 1 loop
1153
         pragma Assert (Source.First in 1 .. Source.Capacity);
1154
         pragma Assert (Source.Last /= Source.First);
1155
         pragma Assert (N (Source.First).Prev = 0);
1156
         pragma Assert (N (Source.Last).Next = 0);
1157
 
1158
         --  Copy first element from Source to Target
1159
 
1160
         X := Source.First;
1161
         Append (Target, N (X).Element);  -- optimize away???
1162
 
1163
         --  Unlink first node of Source
1164
 
1165
         Source.First := N (X).Next;
1166
         N (Source.First).Prev := 0;
1167
 
1168
         Source.Length := Source.Length - 1;
1169
 
1170
         --  The representation invariants for Source have been restored. It is
1171
         --  now safe to free the unlinked node, without fear of corrupting the
1172
         --  active links of Source.
1173
 
1174
         --  Note that the algorithm we use here models similar algorithms used
1175
         --  in the unbounded form of the doubly-linked list container. In that
1176
         --  case, Free is an instantation of Unchecked_Deallocation, which can
1177
         --  fail (because PE will be raised if controlled Finalize fails), so
1178
         --  we must defer the call until the last step. Here in the bounded
1179
         --  form, Free merely links the node we have just "deallocated" onto a
1180
         --  list of inactive nodes, so technically Free cannot fail. However,
1181
         --  for consistency, we handle Free the same way here as we do for the
1182
         --  unbounded form, with the pessimistic assumption that it can fail.
1183
 
1184
         Free (Source, X);
1185
      end loop;
1186
 
1187
      if Source.Length = 1 then
1188
         pragma Assert (Source.First in 1 .. Source.Capacity);
1189
         pragma Assert (Source.Last = Source.First);
1190
         pragma Assert (N (Source.First).Prev = 0);
1191
         pragma Assert (N (Source.Last).Next = 0);
1192
 
1193
         --  Copy element from Source to Target
1194
 
1195
         X := Source.First;
1196
         Append (Target, N (X).Element);
1197
 
1198
         --  Unlink node of Source
1199
 
1200
         Source.First := 0;
1201
         Source.Last := 0;
1202
         Source.Length := 0;
1203
 
1204
         --  Return the unlinked node to the free store
1205
 
1206
         Free (Source, X);
1207
      end if;
1208
   end Move;
1209
 
1210
   ----------
1211
   -- Next --
1212
   ----------
1213
 
1214
   procedure Next (Container : List; Position : in out Cursor) is
1215
   begin
1216
      Position := Next (Container, Position);
1217
   end Next;
1218
 
1219
   function Next (Container : List; Position : Cursor) return Cursor is
1220
   begin
1221
      if Position.Node = 0 then
1222
         return No_Element;
1223
      end if;
1224
 
1225
      if not Has_Element (Container, Position) then
1226
         raise Program_Error with "Position cursor has no element";
1227
      end if;
1228
 
1229
      return (Node => Container.Nodes (Position.Node).Next);
1230
   end Next;
1231
 
1232
   function Next
1233
     (Object   : Iterator;
1234
      Position : Cursor) return Cursor
1235
   is
1236
   begin
1237
      return Next (Object.Container.all, Position);
1238
   end Next;
1239
 
1240
   --------------------
1241
   -- Not_No_Element --
1242
   --------------------
1243
 
1244
   function Not_No_Element (Position : Cursor) return Boolean is
1245
   begin
1246
      return Position /= No_Element;
1247
   end Not_No_Element;
1248
 
1249
   -------------
1250
   -- Prepend --
1251
   -------------
1252
 
1253
   procedure Prepend
1254
     (Container : in out List;
1255
      New_Item  : Element_Type;
1256
      Count     : Count_Type := 1)
1257
   is
1258
   begin
1259
      Insert (Container, First (Container), New_Item, Count);
1260
   end Prepend;
1261
 
1262
   --------------
1263
   -- Previous --
1264
   --------------
1265
 
1266
   procedure Previous (Container : List; Position : in out Cursor) is
1267
   begin
1268
      Position := Previous (Container, Position);
1269
   end Previous;
1270
 
1271
   function Previous (Container : List; Position : Cursor) return Cursor is
1272
   begin
1273
      if Position.Node = 0 then
1274
         return No_Element;
1275
      end if;
1276
 
1277
      if not Has_Element (Container, Position) then
1278
         raise Program_Error with "Position cursor has no element";
1279
      end if;
1280
 
1281
      return (Node => Container.Nodes (Position.Node).Prev);
1282
   end Previous;
1283
 
1284
   function Previous
1285
     (Object   : Iterator;
1286
      Position : Cursor) return Cursor
1287
   is
1288
   begin
1289
      return Previous (Object.Container.all, Position);
1290
   end Previous;
1291
 
1292
   -------------------
1293
   -- Query_Element --
1294
   -------------------
1295
 
1296
   procedure Query_Element
1297
     (Container : List; Position : Cursor;
1298
      Process   : not null access procedure (Element : Element_Type))
1299
   is
1300
      C : List renames Container'Unrestricted_Access.all;
1301
      B : Natural renames C.Busy;
1302
      L : Natural renames C.Lock;
1303
 
1304
   begin
1305
      if not Has_Element (Container, Position) then
1306
         raise Constraint_Error with
1307
           "Position cursor has no element";
1308
      end if;
1309
 
1310
      B := B + 1;
1311
      L := L + 1;
1312
 
1313
      declare
1314
         N : Node_Type renames C.Nodes (Position.Node);
1315
      begin
1316
         Process (N.Element);
1317
      exception
1318
         when others =>
1319
            L := L - 1;
1320
            B := B - 1;
1321
            raise;
1322
      end;
1323
 
1324
      L := L - 1;
1325
      B := B - 1;
1326
   end Query_Element;
1327
 
1328
   ----------
1329
   -- Read --
1330
   ----------
1331
 
1332
   procedure Read
1333
     (Stream : not null access Root_Stream_Type'Class;
1334
      Item   : out List)
1335
   is
1336
      N : Count_Type'Base;
1337
 
1338
   begin
1339
      Clear (Item);
1340
 
1341
      Count_Type'Base'Read (Stream, N);
1342
 
1343
      if N < 0 then
1344
         raise Program_Error with "bad list length";
1345
      end if;
1346
 
1347
      if N = 0 then
1348
         return;
1349
      end if;
1350
 
1351
      if N > Item.Capacity then
1352
         raise Constraint_Error with "length exceeds capacity";
1353
      end if;
1354
 
1355
      for J in 1 .. N loop
1356
         Item.Append (Element_Type'Input (Stream));  -- ???
1357
      end loop;
1358
   end Read;
1359
 
1360
   procedure Read
1361
     (Stream : not null access Root_Stream_Type'Class;
1362
      Item   : out Cursor)
1363
   is
1364
   begin
1365
      raise Program_Error with "attempt to stream list cursor";
1366
   end Read;
1367
 
1368
   ---------------
1369
   -- Reference --
1370
   ---------------
1371
 
1372
   function Constant_Reference
1373
     (Container : List;
1374
      Position  : Cursor) return Constant_Reference_Type
1375
   is
1376
   begin
1377
      if not Has_Element (Container, Position) then
1378
         raise Constraint_Error with "Position cursor has no element";
1379
      end if;
1380
 
1381
      return (Element => Container.Nodes (Position.Node).Element'Access);
1382
   end Constant_Reference;
1383
 
1384
   ---------------------
1385
   -- Replace_Element --
1386
   ---------------------
1387
 
1388
   procedure Replace_Element
1389
     (Container : in out List;
1390
      Position  : Cursor;
1391
      New_Item  : Element_Type)
1392
   is
1393
   begin
1394
      if not Has_Element (Container, Position) then
1395
         raise Constraint_Error with "Position cursor has no element";
1396
      end if;
1397
 
1398
      if Container.Lock > 0 then
1399
         raise Program_Error with
1400
           "attempt to tamper with cursors (list is locked)";
1401
      end if;
1402
 
1403
      pragma Assert
1404
        (Vet (Container, Position), "bad cursor in Replace_Element");
1405
 
1406
      Container.Nodes (Position.Node).Element := New_Item;
1407
   end Replace_Element;
1408
 
1409
   ----------------------
1410
   -- Reverse_Elements --
1411
   ----------------------
1412
 
1413
   procedure Reverse_Elements (Container : in out List) is
1414
      N : Node_Array renames Container.Nodes;
1415
      I : Count_Type := Container.First;
1416
      J : Count_Type := Container.Last;
1417
 
1418
      procedure Swap (L, R : Count_Type);
1419
 
1420
      ----------
1421
      -- Swap --
1422
      ----------
1423
 
1424
      procedure Swap (L, R : Count_Type) is
1425
         LN : constant Count_Type := N (L).Next;
1426
         LP : constant Count_Type := N (L).Prev;
1427
 
1428
         RN : constant Count_Type := N (R).Next;
1429
         RP : constant Count_Type := N (R).Prev;
1430
 
1431
      begin
1432
         if LP /= 0 then
1433
            N (LP).Next := R;
1434
         end if;
1435
 
1436
         if RN /= 0 then
1437
            N (RN).Prev := L;
1438
         end if;
1439
 
1440
         N (L).Next := RN;
1441
         N (R).Prev := LP;
1442
 
1443
         if LN = R then
1444
            pragma Assert (RP = L);
1445
 
1446
            N (L).Prev := R;
1447
            N (R).Next := L;
1448
 
1449
         else
1450
            N (L).Prev := RP;
1451
            N (RP).Next := L;
1452
 
1453
            N (R).Next := LN;
1454
            N (LN).Prev := R;
1455
         end if;
1456
      end Swap;
1457
 
1458
   --  Start of processing for Reverse_Elements
1459
 
1460
   begin
1461
      if Container.Length <= 1 then
1462
         return;
1463
      end if;
1464
 
1465
      pragma Assert (N (Container.First).Prev = 0);
1466
      pragma Assert (N (Container.Last).Next = 0);
1467
 
1468
      if Container.Busy > 0 then
1469
         raise Program_Error with
1470
           "attempt to tamper with elements (list is busy)";
1471
      end if;
1472
 
1473
      Container.First := J;
1474
      Container.Last := I;
1475
      loop
1476
         Swap (L => I, R => J);
1477
 
1478
         J := N (J).Next;
1479
         exit when I = J;
1480
 
1481
         I := N (I).Prev;
1482
         exit when I = J;
1483
 
1484
         Swap (L => J, R => I);
1485
 
1486
         I := N (I).Next;
1487
         exit when I = J;
1488
 
1489
         J := N (J).Prev;
1490
         exit when I = J;
1491
      end loop;
1492
 
1493
      pragma Assert (N (Container.First).Prev = 0);
1494
      pragma Assert (N (Container.Last).Next = 0);
1495
   end Reverse_Elements;
1496
 
1497
   ------------------
1498
   -- Reverse_Find --
1499
   ------------------
1500
 
1501
   function Reverse_Find
1502
     (Container : List;
1503
      Item      : Element_Type;
1504
      Position  : Cursor := No_Element) return Cursor
1505
   is
1506
      CFirst : Count_Type := Position.Node;
1507
 
1508
   begin
1509
      if CFirst = 0 then
1510
         CFirst := Container.First;
1511
      end if;
1512
 
1513
      if Container.Length = 0 then
1514
         return No_Element;
1515
      end if;
1516
 
1517
      while CFirst /= 0 loop
1518
         if Container.Nodes (CFirst).Element = Item then
1519
            return (Node => CFirst);
1520
         end if;
1521
         CFirst := Container.Nodes (CFirst).Prev;
1522
      end loop;
1523
 
1524
      return No_Element;
1525
   end Reverse_Find;
1526
 
1527
   ---------------------
1528
   -- Reverse_Iterate --
1529
   ---------------------
1530
 
1531
   procedure Reverse_Iterate
1532
     (Container : List;
1533
      Process   :
1534
      not null access procedure (Container : List; Position : Cursor))
1535
   is
1536
      C : List renames Container'Unrestricted_Access.all;
1537
      B : Natural renames C.Busy;
1538
 
1539
      Node : Count_Type;
1540
 
1541
   begin
1542
      B := B + 1;
1543
 
1544
      begin
1545
         Node := Container.Last;
1546
         while Node /= 0 loop
1547
            Process (Container, (Node => Node));
1548
            Node := Container.Nodes (Node).Prev;
1549
         end loop;
1550
 
1551
      exception
1552
         when others =>
1553
            B := B - 1;
1554
            raise;
1555
      end;
1556
 
1557
      B := B - 1;
1558
   end Reverse_Iterate;
1559
 
1560
   -----------
1561
   -- Right --
1562
   -----------
1563
 
1564
   function Right (Container : List; Position : Cursor) return List is
1565
      Curs : Cursor := First (Container);
1566
      C    : List (Container.Capacity) := Copy (Container, Container.Capacity);
1567
      Node : Count_Type;
1568
 
1569
   begin
1570
      if Curs = No_Element then
1571
         Clear (C);
1572
         return C;
1573
      end if;
1574
 
1575
      if Position /= No_Element and not Has_Element (Container, Position) then
1576
         raise Constraint_Error;
1577
      end if;
1578
 
1579
      while Curs.Node /= Position.Node loop
1580
         Node := Curs.Node;
1581
         Delete (C, Curs);
1582
         Curs := Next (Container, (Node => Node));
1583
      end loop;
1584
 
1585
      return C;
1586
   end Right;
1587
 
1588
   ------------
1589
   -- Splice --
1590
   ------------
1591
 
1592
   procedure Splice
1593
     (Target : in out List;
1594
      Before : Cursor;
1595
      Source : in out List)
1596
   is
1597
      SN : Node_Array renames Source.Nodes;
1598
 
1599
   begin
1600
      if Before.Node /= 0 then
1601
         pragma Assert (Vet (Target, Before), "bad cursor in Splice");
1602
      end if;
1603
 
1604
      if Target'Address = Source'Address
1605
        or else Source.Length = 0
1606
      then
1607
         return;
1608
      end if;
1609
 
1610
      pragma Assert (SN (Source.First).Prev = 0);
1611
      pragma Assert (SN (Source.Last).Next = 0);
1612
 
1613
      if Target.Length > Count_Type'Base'Last - Source.Length then
1614
         raise Constraint_Error with "new length exceeds maximum";
1615
      end if;
1616
 
1617
      if Target.Length + Source.Length > Target.Capacity then
1618
         raise Constraint_Error;
1619
      end if;
1620
 
1621
      if Target.Busy > 0 then
1622
         raise Program_Error with
1623
           "attempt to tamper with cursors of Target (list is busy)";
1624
      end if;
1625
 
1626
      if Source.Busy > 0 then
1627
         raise Program_Error with
1628
           "attempt to tamper with cursors of Source (list is busy)";
1629
      end if;
1630
 
1631
      loop
1632
         Insert (Target, Before, SN (Source.Last).Element);
1633
         Delete_Last (Source);
1634
         exit when Is_Empty (Source);
1635
      end loop;
1636
   end Splice;
1637
 
1638
   procedure Splice
1639
     (Target   : in out List;
1640
      Before   : Cursor;
1641
      Source   : in out List;
1642
      Position : in out Cursor)
1643
   is
1644
      Target_Position : Cursor;
1645
 
1646
   begin
1647
      if Target'Address = Source'Address then
1648
         Splice (Target, Before, Position);
1649
         return;
1650
      end if;
1651
 
1652
      if Position.Node = 0 then
1653
         raise Constraint_Error with "Position cursor has no element";
1654
      end if;
1655
 
1656
      pragma Assert (Vet (Source, Position), "bad Position cursor in Splice");
1657
 
1658
      if Target.Length >= Target.Capacity then
1659
         raise Constraint_Error;
1660
      end if;
1661
 
1662
      if Target.Busy > 0 then
1663
         raise Program_Error with
1664
           "attempt to tamper with cursors of Target (list is busy)";
1665
      end if;
1666
 
1667
      if Source.Busy > 0 then
1668
         raise Program_Error with
1669
           "attempt to tamper with cursors of Source (list is busy)";
1670
      end if;
1671
 
1672
      Insert
1673
        (Container => Target,
1674
         Before    => Before,
1675
         New_Item  => Source.Nodes (Position.Node).Element,
1676
         Position  => Target_Position);
1677
 
1678
      Delete (Source, Position);
1679
      Position := Target_Position;
1680
   end Splice;
1681
 
1682
   procedure Splice
1683
     (Container : in out List;
1684
      Before    : Cursor;
1685
      Position  : Cursor)
1686
   is
1687
      N : Node_Array renames Container.Nodes;
1688
 
1689
   begin
1690
      if Before.Node /= 0 then
1691
         pragma Assert
1692
           (Vet (Container, Before), "bad Before cursor in Splice");
1693
      end if;
1694
 
1695
      if Position.Node = 0 then
1696
         raise Constraint_Error with "Position cursor has no element";
1697
      end if;
1698
 
1699
      pragma Assert
1700
        (Vet (Container, Position), "bad Position cursor in Splice");
1701
 
1702
      if Position.Node = Before.Node
1703
        or else N (Position.Node).Next = Before.Node
1704
      then
1705
         return;
1706
      end if;
1707
 
1708
      pragma Assert (Container.Length >= 2);
1709
 
1710
      if Container.Busy > 0 then
1711
         raise Program_Error with
1712
           "attempt to tamper with elements (list is busy)";
1713
      end if;
1714
 
1715
      if Before.Node = 0 then
1716
         pragma Assert (Position.Node /= Container.Last);
1717
 
1718
         if Position.Node = Container.First then
1719
            Container.First := N (Position.Node).Next;
1720
            N (Container.First).Prev := 0;
1721
 
1722
         else
1723
            N (N (Position.Node).Prev).Next := N (Position.Node).Next;
1724
            N (N (Position.Node).Next).Prev := N (Position.Node).Prev;
1725
         end if;
1726
 
1727
         N (Container.Last).Next := Position.Node;
1728
         N (Position.Node).Prev := Container.Last;
1729
 
1730
         Container.Last := Position.Node;
1731
         N (Container.Last).Next := 0;
1732
 
1733
         return;
1734
      end if;
1735
 
1736
      if Before.Node = Container.First then
1737
         pragma Assert (Position.Node /= Container.First);
1738
 
1739
         if Position.Node = Container.Last then
1740
            Container.Last := N (Position.Node).Prev;
1741
            N (Container.Last).Next := 0;
1742
 
1743
         else
1744
            N (N (Position.Node).Prev).Next := N (Position.Node).Next;
1745
            N (N (Position.Node).Next).Prev := N (Position.Node).Prev;
1746
         end if;
1747
 
1748
         N (Container.First).Prev := Position.Node;
1749
         N (Position.Node).Next := Container.First;
1750
 
1751
         Container.First := Position.Node;
1752
         N (Container.First).Prev := 0;
1753
 
1754
         return;
1755
      end if;
1756
 
1757
      if Position.Node = Container.First then
1758
         Container.First := N (Position.Node).Next;
1759
         N (Container.First).Prev := 0;
1760
 
1761
      elsif Position.Node = Container.Last then
1762
         Container.Last := N (Position.Node).Prev;
1763
         N (Container.Last).Next := 0;
1764
 
1765
      else
1766
         N (N (Position.Node).Prev).Next := N (Position.Node).Next;
1767
         N (N (Position.Node).Next).Prev := N (Position.Node).Prev;
1768
      end if;
1769
 
1770
      N (N (Before.Node).Prev).Next := Position.Node;
1771
      N (Position.Node).Prev := N (Before.Node).Prev;
1772
 
1773
      N (Before.Node).Prev := Position.Node;
1774
      N (Position.Node).Next := Before.Node;
1775
 
1776
      pragma Assert (N (Container.First).Prev = 0);
1777
      pragma Assert (N (Container.Last).Next = 0);
1778
   end Splice;
1779
 
1780
   ------------------
1781
   -- Strict_Equal --
1782
   ------------------
1783
 
1784
   function Strict_Equal (Left, Right : List) return Boolean is
1785
      CL : Count_Type := Left.First;
1786
      CR : Count_Type := Right.First;
1787
 
1788
   begin
1789
      while CL /= 0 or CR /= 0 loop
1790
         if CL /= CR or else
1791
           Left.Nodes (CL).Element /= Right.Nodes (CL).Element
1792
         then
1793
            return False;
1794
         end if;
1795
 
1796
         CL := Left.Nodes (CL).Next;
1797
         CR := Right.Nodes (CR).Next;
1798
      end loop;
1799
 
1800
      return True;
1801
   end Strict_Equal;
1802
 
1803
   ----------
1804
   -- Swap --
1805
   ----------
1806
 
1807
   procedure Swap
1808
     (Container : in out List;
1809
      I, J      : Cursor)
1810
   is
1811
   begin
1812
      if I.Node = 0 then
1813
         raise Constraint_Error with "I cursor has no element";
1814
      end if;
1815
 
1816
      if J.Node = 0 then
1817
         raise Constraint_Error with "J cursor has no element";
1818
      end if;
1819
 
1820
      if I.Node = J.Node then
1821
         return;
1822
      end if;
1823
 
1824
      if Container.Lock > 0 then
1825
         raise Program_Error with
1826
           "attempt to tamper with cursors (list is locked)";
1827
      end if;
1828
 
1829
      pragma Assert (Vet (Container, I), "bad I cursor in Swap");
1830
      pragma Assert (Vet (Container, J), "bad J cursor in Swap");
1831
 
1832
      declare
1833
         NN : Node_Array renames Container.Nodes;
1834
         NI : Node_Type renames NN (I.Node);
1835
         NJ : Node_Type renames NN (J.Node);
1836
 
1837
         EI_Copy : constant Element_Type := NI.Element;
1838
 
1839
      begin
1840
         NI.Element := NJ.Element;
1841
         NJ.Element := EI_Copy;
1842
      end;
1843
   end Swap;
1844
 
1845
   ----------------
1846
   -- Swap_Links --
1847
   ----------------
1848
 
1849
   procedure Swap_Links
1850
     (Container : in out List;
1851
      I, J      : Cursor)
1852
   is
1853
      I_Next, J_Next : Cursor;
1854
 
1855
   begin
1856
      if I.Node = 0 then
1857
         raise Constraint_Error with "I cursor has no element";
1858
      end if;
1859
 
1860
      if J.Node = 0 then
1861
         raise Constraint_Error with "J cursor has no element";
1862
      end if;
1863
 
1864
      if I.Node = J.Node then
1865
         return;
1866
      end if;
1867
 
1868
      if Container.Busy > 0 then
1869
         raise Program_Error with
1870
           "attempt to tamper with elements (list is busy)";
1871
      end if;
1872
 
1873
      pragma Assert (Vet (Container, I), "bad I cursor in Swap_Links");
1874
      pragma Assert (Vet (Container, J), "bad J cursor in Swap_Links");
1875
 
1876
      I_Next := Next (Container, I);
1877
 
1878
      if I_Next = J then
1879
         Splice (Container, Before => I, Position => J);
1880
 
1881
      else
1882
         J_Next := Next (Container, J);
1883
 
1884
         if J_Next = I then
1885
            Splice (Container, Before => J, Position => I);
1886
 
1887
         else
1888
            pragma Assert (Container.Length >= 3);
1889
            Splice (Container, Before => I_Next, Position => J);
1890
            Splice (Container, Before => J_Next, Position => I);
1891
         end if;
1892
      end if;
1893
   end Swap_Links;
1894
 
1895
   --------------------
1896
   -- Update_Element --
1897
   --------------------
1898
 
1899
   procedure Update_Element
1900
     (Container : in out List;
1901
      Position  : Cursor;
1902
      Process   : not null access procedure (Element : in out Element_Type))
1903
   is
1904
   begin
1905
      if Position.Node = 0 then
1906
         raise Constraint_Error with "Position cursor has no element";
1907
      end if;
1908
 
1909
      pragma Assert
1910
        (Vet (Container, Position), "bad cursor in Update_Element");
1911
 
1912
      declare
1913
         B : Natural renames Container.Busy;
1914
         L : Natural renames Container.Lock;
1915
 
1916
      begin
1917
         B := B + 1;
1918
         L := L + 1;
1919
 
1920
         declare
1921
            N : Node_Type renames Container.Nodes (Position.Node);
1922
         begin
1923
            Process (N.Element);
1924
         exception
1925
            when others =>
1926
               L := L - 1;
1927
               B := B - 1;
1928
               raise;
1929
         end;
1930
 
1931
         L := L - 1;
1932
         B := B - 1;
1933
      end;
1934
   end Update_Element;
1935
 
1936
   ---------
1937
   -- Vet --
1938
   ---------
1939
 
1940
   function Vet (L : List; Position : Cursor) return Boolean is
1941
      N : Node_Array renames L.Nodes;
1942
 
1943
   begin
1944
      if L.Length = 0 then
1945
         return False;
1946
      end if;
1947
 
1948
      if L.First = 0 then
1949
         return False;
1950
      end if;
1951
 
1952
      if L.Last = 0 then
1953
         return False;
1954
      end if;
1955
 
1956
      if Position.Node > L.Capacity then
1957
         return False;
1958
      end if;
1959
 
1960
      if N (Position.Node).Prev < 0
1961
        or else N (Position.Node).Prev > L.Capacity
1962
      then
1963
         return False;
1964
      end if;
1965
 
1966
      if N (Position.Node).Next > L.Capacity then
1967
         return False;
1968
      end if;
1969
 
1970
      if N (L.First).Prev /= 0 then
1971
         return False;
1972
      end if;
1973
 
1974
      if N (L.Last).Next /= 0 then
1975
         return False;
1976
      end if;
1977
 
1978
      if N (Position.Node).Prev = 0
1979
        and then Position.Node /= L.First
1980
      then
1981
         return False;
1982
      end if;
1983
 
1984
      if N (Position.Node).Next = 0
1985
        and then Position.Node /= L.Last
1986
      then
1987
         return False;
1988
      end if;
1989
 
1990
      if L.Length = 1 then
1991
         return L.First = L.Last;
1992
      end if;
1993
 
1994
      if L.First = L.Last then
1995
         return False;
1996
      end if;
1997
 
1998
      if N (L.First).Next = 0 then
1999
         return False;
2000
      end if;
2001
 
2002
      if N (L.Last).Prev = 0 then
2003
         return False;
2004
      end if;
2005
 
2006
      if N (N (L.First).Next).Prev /= L.First then
2007
         return False;
2008
      end if;
2009
 
2010
      if N (N (L.Last).Prev).Next /= L.Last then
2011
         return False;
2012
      end if;
2013
 
2014
      if L.Length = 2 then
2015
         if N (L.First).Next /= L.Last then
2016
            return False;
2017
         end if;
2018
 
2019
         if N (L.Last).Prev /= L.First then
2020
            return False;
2021
         end if;
2022
 
2023
         return True;
2024
      end if;
2025
 
2026
      if N (L.First).Next = L.Last then
2027
         return False;
2028
      end if;
2029
 
2030
      if N (L.Last).Prev = L.First then
2031
         return False;
2032
      end if;
2033
 
2034
      if Position.Node = L.First then
2035
         return True;
2036
      end if;
2037
 
2038
      if Position.Node = L.Last then
2039
         return True;
2040
      end if;
2041
 
2042
      if N (Position.Node).Next = 0 then
2043
         return False;
2044
      end if;
2045
 
2046
      if N (Position.Node).Prev = 0 then
2047
         return False;
2048
      end if;
2049
 
2050
      if N (N (Position.Node).Next).Prev /= Position.Node then
2051
         return False;
2052
      end if;
2053
 
2054
      if N (N (Position.Node).Prev).Next /= Position.Node then
2055
         return False;
2056
      end if;
2057
 
2058
      if L.Length = 3 then
2059
         if N (L.First).Next /= Position.Node then
2060
            return False;
2061
         end if;
2062
 
2063
         if N (L.Last).Prev /= Position.Node then
2064
            return False;
2065
         end if;
2066
      end if;
2067
 
2068
      return True;
2069
   end Vet;
2070
 
2071
   -----------
2072
   -- Write --
2073
   -----------
2074
 
2075
   procedure Write
2076
     (Stream : not null access Root_Stream_Type'Class;
2077
      Item   : List)
2078
   is
2079
      N    : Node_Array renames Item.Nodes;
2080
      Node : Count_Type;
2081
 
2082
   begin
2083
      Count_Type'Base'Write (Stream, Item.Length);
2084
 
2085
      Node := Item.First;
2086
      while Node /= 0 loop
2087
         Element_Type'Write (Stream, N (Node).Element);
2088
         Node := N (Node).Next;
2089
      end loop;
2090
   end Write;
2091
 
2092
   procedure Write
2093
     (Stream : not null access Root_Stream_Type'Class;
2094
      Item   : Cursor)
2095
   is
2096
   begin
2097
      raise Program_Error with "attempt to stream list cursor";
2098
   end Write;
2099
 
2100
end Ada.Containers.Formal_Doubly_Linked_Lists;

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