1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT LIBRARY COMPONENTS                          --
4--                                                                          --
5--     A D A . C O N T A I N E R S . O R D E R E D _ M U L T I S E T S      --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2004-2018, 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
30--  The ordered multiset container is similar to the ordered set, but with the
31--  difference that multiple equivalent elements are allowed. It also provides
32--  additional operations, to iterate over items that are equivalent.
33
34private with Ada.Containers.Red_Black_Trees;
35private with Ada.Finalization;
36private with Ada.Streams;
37with Ada.Iterator_Interfaces;
38
39generic
40   type Element_Type is private;
41
42   with function "<" (Left, Right : Element_Type) return Boolean is <>;
43   with function "=" (Left, Right : Element_Type) return Boolean is <>;
44
45package Ada.Containers.Ordered_Multisets is
46   pragma Annotate (CodePeer, Skip_Analysis);
47   pragma Preelaborate;
48   pragma Remote_Types;
49
50   function Equivalent_Elements (Left, Right : Element_Type) return Boolean;
51   --  Returns False if Left is less than Right, or Right is less than Left;
52   --  otherwise, it returns True.
53
54   type Set is tagged private
55   with Constant_Indexing => Constant_Reference,
56        Default_Iterator  => Iterate,
57        Iterator_Element  => Element_Type;
58
59   pragma Preelaborable_Initialization (Set);
60
61   type Cursor is private;
62   pragma Preelaborable_Initialization (Cursor);
63
64   Empty_Set : constant Set;
65   --  The default value for set objects declared without an explicit
66   --  initialization expression.
67
68   No_Element : constant Cursor;
69   --  The default value for cursor objects declared without an explicit
70   --  initialization expression.
71
72   function Has_Element (Position : Cursor) return Boolean;
73   --  Equivalent to Position /= No_Element
74
75   package Set_Iterator_Interfaces is new
76     Ada.Iterator_Interfaces (Cursor, Has_Element);
77
78   function "=" (Left, Right : Set) return Boolean;
79   --  If Left denotes the same set object as Right, then equality returns
80   --  True. If the length of Left is different from the length of Right, then
81   --  it returns False. Otherwise, set equality iterates over Left and Right,
82   --  comparing the element of Left to the element of Right using the equality
83   --  operator for elements. If the elements compare False, then the iteration
84   --  terminates and set equality returns False. Otherwise, if all elements
85   --  compare True, then set equality returns True.
86
87   function Equivalent_Sets (Left, Right : Set) return Boolean;
88   --  Similar to set equality, but with the difference that elements are
89   --  compared for equivalence instead of equality.
90
91   function To_Set (New_Item : Element_Type) return Set;
92   --  Constructs a set object with New_Item as its single element
93
94   function Length (Container : Set) return Count_Type;
95   --  Returns the total number of elements in Container
96
97   function Is_Empty (Container : Set) return Boolean;
98   --  Returns True if Container.Length is 0
99
100   procedure Clear (Container : in out Set);
101   --  Deletes all elements from Container
102
103   function Element (Position : Cursor) return Element_Type;
104   --  If Position equals No_Element, then Constraint_Error is raised.
105   --  Otherwise, function Element returns the element designed by Position.
106
107   procedure Replace_Element
108     (Container : in out Set;
109      Position  : Cursor;
110      New_Item  : Element_Type);
111   --  If Position equals No_Element, then Constraint_Error is raised. If
112   --  Position is associated with a set different from Container, then
113   --  Program_Error is raised. If New_Item is equivalent to the element
114   --  designated by Position, then if Container is locked (element tampering
115   --  has been attempted), Program_Error is raised; otherwise, the element
116   --  designated by Position is assigned the value of New_Item. If New_Item is
117   --  not equivalent to the element designated by Position, then if the
118   --  container is busy (cursor tampering has been attempted), Program_Error
119   --  is raised; otherwise, the element designed by Position is assigned the
120   --  value of New_Item, and the node is moved to its new position (in
121   --  canonical insertion order).
122
123   procedure Query_Element
124     (Position : Cursor;
125      Process  : not null access procedure (Element : Element_Type));
126   --  If Position equals No_Element, then Constraint_Error is
127   --  raised. Otherwise, it calls Process with the element designated by
128   --  Position as the parameter. This call locks the container, so attempts to
129   --  change the value of the element while Process is executing (to "tamper
130   --  with elements") will raise Program_Error.
131
132   type Constant_Reference_Type
133     (Element : not null access constant Element_Type) is private
134        with Implicit_Dereference => Element;
135
136   function Constant_Reference
137     (Container : aliased Set;
138      Position  : Cursor) return Constant_Reference_Type;
139   pragma Inline (Constant_Reference);
140
141   procedure Assign (Target : in out Set; Source : Set);
142
143   function Copy (Source : Set) return Set;
144
145   procedure Move (Target : in out Set; Source : in out Set);
146   --  If Target denotes the same object as Source, the operation does
147   --  nothing. If either Target or Source is busy (cursor tampering is
148   --  attempted), then it raises Program_Error. Otherwise, Target is cleared,
149   --  and the nodes from Source are moved (not copied) to Target (so Source
150   --  becomes empty).
151
152   procedure Insert
153     (Container : in out Set;
154      New_Item  : Element_Type;
155      Position  : out Cursor);
156   --  Insert adds New_Item to Container, and returns cursor Position
157   --  designating the newly inserted node. The node is inserted after any
158   --  existing elements less than or equivalent to New_Item (and before any
159   --  elements greater than New_Item). Note that the issue of where the new
160   --  node is inserted relative to equivalent elements does not arise for
161   --  unique-key containers, since in that case the insertion would simply
162   --  fail. For a multiple-key container (the case here), insertion always
163   --  succeeds, and is defined such that the new item is positioned after any
164   --  equivalent elements already in the container.
165
166   procedure Insert
167     (Container : in out Set;
168      New_Item  : Element_Type);
169   --  Inserts New_Item in Container, but does not return a cursor designating
170   --  the newly-inserted node.
171
172--  TODO: include Replace too???
173--
174--     procedure Replace
175--       (Container : in out Set;
176--        New_Item  : Element_Type);
177
178   procedure Exclude
179     (Container : in out Set;
180      Item      : Element_Type);
181   --  Deletes from Container all of the elements equivalent to Item
182
183   procedure Delete
184     (Container : in out Set;
185      Item      : Element_Type);
186   --  Deletes from Container all of the elements equivalent to Item. If there
187   --  are no elements equivalent to Item, then it raises Constraint_Error.
188
189   procedure Delete
190     (Container : in out Set;
191      Position  : in out Cursor);
192   --  If Position equals No_Element, then Constraint_Error is raised. If
193   --  Position is associated with a set different from Container, then
194   --  Program_Error is raised. Otherwise, the node designated by Position is
195   --  removed from Container, and Position is set to No_Element.
196
197   procedure Delete_First (Container : in out Set);
198   --  Removes the first node from Container
199
200   procedure Delete_Last (Container : in out Set);
201   --  Removes the last node from Container
202
203   procedure Union (Target : in out Set; Source : Set);
204   --  If Target is busy (cursor tampering is attempted), the Program_Error is
205   --  raised. Otherwise, it inserts each element of Source into
206   --  Target. Elements are inserted in the canonical order for multisets, such
207   --  that the elements from Source are inserted after equivalent elements
208   --  already in Target.
209
210   function Union (Left, Right : Set) return Set;
211   --  Returns a set comprising the all elements from Left and all of the
212   --  elements from Right. The elements from Right follow the equivalent
213   --  elements from Left.
214
215   function "or" (Left, Right : Set) return Set renames Union;
216
217   procedure Intersection (Target : in out Set; Source : Set);
218   --  If Target denotes the same object as Source, the operation does
219   --  nothing. If Target is busy (cursor tampering is attempted),
220   --  Program_Error is raised. Otherwise, the elements in Target having no
221   --  equivalent element in Source are deleted from Target.
222
223   function Intersection (Left, Right : Set) return Set;
224   --  If Left denotes the same object as Right, then the function returns a
225   --  copy of Left. Otherwise, it returns a set comprising the equivalent
226   --  elements from both Left and Right. Items are inserted in the result set
227   --  in canonical order, such that the elements from Left precede the
228   --  equivalent elements from Right.
229
230   function "and" (Left, Right : Set) return Set renames Intersection;
231
232   procedure Difference (Target : in out Set; Source : Set);
233   --  If Target is busy (cursor tampering is attempted), then Program_Error is
234   --  raised. Otherwise, the elements in Target that are equivalent to
235   --  elements in Source are deleted from Target.
236
237   function Difference (Left, Right : Set) return Set;
238   --  Returns a set comprising the elements from Left that have no equivalent
239   --  element in Right.
240
241   function "-" (Left, Right : Set) return Set renames Difference;
242
243   procedure Symmetric_Difference (Target : in out Set; Source : Set);
244   --  If Target is busy, then Program_Error is raised. Otherwise, the elements
245   --  in Target equivalent to elements in Source are deleted from Target, and
246   --  the elements in Source not equivalent to elements in Target are inserted
247   --  into Target.
248
249   function Symmetric_Difference (Left, Right : Set) return Set;
250   --  Returns a set comprising the union of the elements from Target having no
251   --  equivalent in Source, and the elements of Source having no equivalent in
252   --  Target.
253
254   function "xor" (Left, Right : Set) return Set renames Symmetric_Difference;
255
256   function Overlap (Left, Right : Set) return Boolean;
257   --  Returns True if Left contains an element equivalent to an element of
258   --  Right.
259
260   function Is_Subset (Subset : Set; Of_Set : Set) return Boolean;
261   --  Returns True if every element in Subset has an equivalent element in
262   --  Of_Set.
263
264   function First (Container : Set) return Cursor;
265   --  If Container is empty, the function returns No_Element. Otherwise, it
266   --  returns a cursor designating the smallest element.
267
268   function First_Element (Container : Set) return Element_Type;
269   --  Equivalent to Element (First (Container))
270
271   function Last (Container : Set) return Cursor;
272   --  If Container is empty, the function returns No_Element. Otherwise, it
273   --  returns a cursor designating the largest element.
274
275   function Last_Element (Container : Set) return Element_Type;
276   --  Equivalent to Element (Last (Container))
277
278   function Next (Position : Cursor) return Cursor;
279   --  If Position equals No_Element or Last (Container), the function returns
280   --  No_Element. Otherwise, it returns a cursor designating the node that
281   --  immediately follows (as per the insertion order) the node designated by
282   --  Position.
283
284   procedure Next (Position : in out Cursor);
285   --  Equivalent to Position := Next (Position)
286
287   function Previous (Position : Cursor) return Cursor;
288   --  If Position equals No_Element or First (Container), the function returns
289   --  No_Element. Otherwise, it returns a cursor designating the node that
290   --  immediately precedes (as per the insertion order) the node designated by
291   --  Position.
292
293   procedure Previous (Position : in out Cursor);
294   --  Equivalent to Position := Previous (Position)
295
296   function Find (Container : Set; Item : Element_Type) return Cursor;
297   --  Returns a cursor designating the first element in Container equivalent
298   --  to Item. If there is no equivalent element, it returns No_Element.
299
300   function Floor (Container : Set; Item : Element_Type) return Cursor;
301   --  If Container is empty, the function returns No_Element. If Item is
302   --  equivalent to elements in Container, it returns a cursor designating the
303   --  first equivalent element. Otherwise, it returns a cursor designating the
304   --  largest element less than Item, or No_Element if all elements are
305   --  greater than Item.
306
307   function Ceiling (Container : Set; Item : Element_Type) return Cursor;
308   --  If Container is empty, the function returns No_Element. If Item is
309   --  equivalent to elements of Container, it returns a cursor designating the
310   --  last equivalent element. Otherwise, it returns a cursor designating the
311   --  smallest element greater than Item, or No_Element if all elements are
312   --  less than Item.
313
314   function Contains (Container : Set; Item : Element_Type) return Boolean;
315   --  Equivalent to Container.Find (Item) /= No_Element
316
317   function "<" (Left, Right : Cursor) return Boolean;
318   --  Equivalent to Element (Left) < Element (Right)
319
320   function ">" (Left, Right : Cursor) return Boolean;
321   --  Equivalent to Element (Right) < Element (Left)
322
323   function "<" (Left : Cursor; Right : Element_Type) return Boolean;
324   --  Equivalent to Element (Left) < Right
325
326   function ">" (Left : Cursor; Right : Element_Type) return Boolean;
327   --  Equivalent to Right < Element (Left)
328
329   function "<" (Left : Element_Type; Right : Cursor) return Boolean;
330   --  Equivalent to Left < Element (Right)
331
332   function ">" (Left : Element_Type; Right : Cursor) return Boolean;
333   --  Equivalent to Element (Right) < Left
334
335   procedure Iterate
336     (Container : Set;
337      Process   : not null access procedure (Position : Cursor));
338   --  Calls Process with a cursor designating each element of Container, in
339   --  order from Container.First to Container.Last.
340
341   procedure Reverse_Iterate
342     (Container : Set;
343      Process   : not null access procedure (Position : Cursor));
344   --  Calls Process with a cursor designating each element of Container, in
345   --  order from Container.Last to Container.First.
346
347   procedure Iterate
348     (Container : Set;
349      Item      : Element_Type;
350      Process   : not null access procedure (Position : Cursor));
351   --  Call Process with a cursor designating each element equivalent to Item,
352   --  in order from Container.Floor (Item) to Container.Ceiling (Item).
353
354   procedure Reverse_Iterate
355     (Container : Set;
356      Item      : Element_Type;
357      Process   : not null access procedure (Position : Cursor));
358   --  Call Process with a cursor designating each element equivalent to Item,
359   --  in order from Container.Ceiling (Item) to Container.Floor (Item).
360
361   function Iterate
362     (Container : Set)
363      return Set_Iterator_Interfaces.Reversible_Iterator'class;
364
365   function Iterate
366     (Container : Set;
367      Start     : Cursor)
368      return Set_Iterator_Interfaces.Reversible_Iterator'class;
369
370   generic
371      type Key_Type (<>) is private;
372
373      with function Key (Element : Element_Type) return Key_Type;
374
375      with function "<" (Left, Right : Key_Type) return Boolean is <>;
376
377   package Generic_Keys is
378
379      function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
380      --  Returns False if Left is less than Right, or Right is less than Left;
381      --  otherwise, it returns True.
382
383      function Key (Position : Cursor) return Key_Type;
384      --  Equivalent to Key (Element (Position))
385
386      function Element (Container : Set; Key : Key_Type) return Element_Type;
387      --  Equivalent to Element (Find (Container, Key))
388
389      procedure Exclude (Container : in out Set; Key : Key_Type);
390      --  Deletes from Container any elements whose key is equivalent to Key
391
392      procedure Delete (Container : in out Set; Key : Key_Type);
393      --  Deletes from Container any elements whose key is equivalent to
394      --  Key. If there are no such elements, then it raises Constraint_Error.
395
396      function Find (Container : Set; Key : Key_Type) return Cursor;
397      --  Returns a cursor designating the first element in Container whose key
398      --  is equivalent to Key. If there is no equivalent element, it returns
399      --  No_Element.
400
401      function Floor (Container : Set; Key : Key_Type) return Cursor;
402      --  If Container is empty, the function returns No_Element. If Item is
403      --  equivalent to the keys of elements in Container, it returns a cursor
404      --  designating the first such element. Otherwise, it returns a cursor
405      --  designating the largest element whose key is less than Item, or
406      --  No_Element if all keys are greater than Item.
407
408      function Ceiling (Container : Set; Key : Key_Type) return Cursor;
409      --  If Container is empty, the function returns No_Element. If Item is
410      --  equivalent to the keys of elements of Container, it returns a cursor
411      --  designating the last such element. Otherwise, it returns a cursor
412      --  designating the smallest element whose key is greater than Item, or
413      --  No_Element if all keys are less than Item.
414
415      function Contains (Container : Set; Key : Key_Type) return Boolean;
416      --  Equivalent to Find (Container, Key) /= No_Element
417
418      procedure Update_Element  -- Update_Element_Preserving_Key ???
419        (Container : in out Set;
420         Position  : Cursor;
421         Process   : not null access
422                       procedure (Element : in out Element_Type));
423      --  If Position equals No_Element, then Constraint_Error is raised. If
424      --  Position is associated with a set object different from Container,
425      --  then Program_Error is raised. Otherwise, it makes a copy of the key
426      --  of the element designated by Position, and then calls Process with
427      --  the element as the parameter. Update_Element then compares the key
428      --  value obtained before calling Process to the key value obtained from
429      --  the element after calling Process. If the keys are equivalent then
430      --  the operation terminates. If Container is busy (cursor tampering has
431      --  been attempted), then Program_Error is raised. Otherwise, the node
432      --  is moved to its new position (in canonical order).
433
434      procedure Iterate
435        (Container : Set;
436         Key       : Key_Type;
437         Process   : not null access procedure (Position : Cursor));
438      --  Call Process with a cursor designating each element equivalent to
439      --  Key, in order from Floor (Container, Key) to
440      --  Ceiling (Container, Key).
441
442      procedure Reverse_Iterate
443        (Container : Set;
444         Key       : Key_Type;
445         Process   : not null access procedure (Position : Cursor));
446      --  Call Process with a cursor designating each element equivalent to
447      --  Key, in order from Ceiling (Container, Key) to
448      --  Floor (Container, Key).
449
450   end Generic_Keys;
451
452private
453
454   pragma Inline (Next);
455   pragma Inline (Previous);
456
457   type Node_Type;
458   type Node_Access is access Node_Type;
459
460   type Node_Type is limited record
461      Parent  : Node_Access;
462      Left    : Node_Access;
463      Right   : Node_Access;
464      Color   : Red_Black_Trees.Color_Type := Red_Black_Trees.Red;
465      Element : Element_Type;
466   end record;
467
468   package Tree_Types is
469     new Red_Black_Trees.Generic_Tree_Types (Node_Type, Node_Access);
470
471   type Set is new Ada.Finalization.Controlled with record
472      Tree : Tree_Types.Tree_Type;
473   end record;
474
475   overriding procedure Adjust (Container : in out Set);
476
477   overriding procedure Finalize (Container : in out Set) renames Clear;
478
479   use Red_Black_Trees;
480   use Tree_Types, Tree_Types.Implementation;
481   use Ada.Finalization;
482   use Ada.Streams;
483
484   type Set_Access is access all Set;
485   for Set_Access'Storage_Size use 0;
486
487   --  In all predefined libraries the following type is controlled, for proper
488   --  management of tampering checks. For performance reason we omit this
489   --  machinery for multisets, which are used in a number of our tools.
490
491   type Reference_Control_Type is record
492      Container : Set_Access;
493   end record;
494
495   type Constant_Reference_Type
496     (Element : not null access constant Element_Type) is record
497      Control : Reference_Control_Type :=
498        raise Program_Error with "uninitialized reference";
499      --  The RM says, "The default initialization of an object of
500      --  type Constant_Reference_Type or Reference_Type propagates
501      --  Program_Error."
502   end record;
503
504   type Cursor is record
505      Container : Set_Access;
506      Node      : Node_Access;
507   end record;
508
509   procedure Write
510     (Stream : not null access Root_Stream_Type'Class;
511      Item   : Cursor);
512
513   for Cursor'Write use Write;
514
515   procedure Read
516     (Stream : not null access Root_Stream_Type'Class;
517      Item   : out Cursor);
518
519   for Cursor'Read use Read;
520
521   No_Element : constant Cursor := Cursor'(null, null);
522
523   procedure Write
524     (Stream    : not null access Root_Stream_Type'Class;
525      Container : Set);
526
527   for Set'Write use Write;
528
529   procedure Read
530     (Stream    : not null access Root_Stream_Type'Class;
531      Container : out Set);
532
533   for Set'Read use Read;
534
535   procedure Read
536     (Stream : not null access Root_Stream_Type'Class;
537      Item   : out Constant_Reference_Type);
538
539   for Constant_Reference_Type'Read use Read;
540
541   procedure Write
542     (Stream : not null access Root_Stream_Type'Class;
543      Item   : Constant_Reference_Type);
544
545   for Constant_Reference_Type'Write use Write;
546
547   Empty_Set : constant Set := (Controlled with others => <>);
548
549   type Iterator is new Limited_Controlled and
550     Set_Iterator_Interfaces.Reversible_Iterator with
551   record
552      Container : Set_Access;
553      Node      : Node_Access;
554   end record
555     with Disable_Controlled => not T_Check;
556
557   overriding procedure Finalize (Object : in out Iterator);
558
559   overriding function First (Object : Iterator) return Cursor;
560   overriding function Last  (Object : Iterator) return Cursor;
561
562   overriding function Next
563     (Object   : Iterator;
564      Position : Cursor) return Cursor;
565
566   overriding function Previous
567     (Object   : Iterator;
568      Position : Cursor) return Cursor;
569
570end Ada.Containers.Ordered_Multisets;
571