1 ------------------------------------------------------------------------------
3 -- GNAT LIBRARY COMPONENTS --
5 -- A D A . C O N T A I N E R S . H A S H E D _ S E T S --
9 -- Copyright (C) 2004-2012, Free Software Foundation, Inc. --
11 -- This specification is derived from the Ada Reference Manual for use with --
12 -- GNAT. The copyright notice above, and the license provisions that follow --
13 -- apply solely to the contents of the part following the private keyword. --
15 -- GNAT is free software; you can redistribute it and/or modify it under --
16 -- terms of the GNU General Public License as published by the Free Soft- --
17 -- ware Foundation; either version 3, or (at your option) any later ver- --
18 -- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
19 -- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
20 -- or FITNESS FOR A PARTICULAR PURPOSE. --
22 -- As a special exception under Section 7 of GPL version 3, you are granted --
23 -- additional permissions described in the GCC Runtime Library Exception, --
24 -- version 3.1, as published by the Free Software Foundation. --
26 -- You should have received a copy of the GNU General Public License and --
27 -- a copy of the GCC Runtime Library Exception along with this program; --
28 -- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
29 -- <http://www.gnu.org/licenses/>. --
31 -- This unit was originally developed by Matthew J Heaney. --
32 ------------------------------------------------------------------------------
34 with Ada
.Iterator_Interfaces
;
36 private with Ada
.Containers
.Hash_Tables
;
37 private with Ada
.Streams
;
38 private with Ada
.Finalization
;
41 type Element_Type
is private;
43 with function Hash
(Element
: Element_Type
) return Hash_Type
;
45 with function Equivalent_Elements
46 (Left
, Right
: Element_Type
) return Boolean;
48 with function "=" (Left
, Right
: Element_Type
) return Boolean is <>;
50 package Ada
.Containers
.Hashed_Sets
is
54 type Set
is tagged private
56 Constant_Indexing
=> Constant_Reference
,
57 Default_Iterator
=> Iterate
,
58 Iterator_Element
=> Element_Type
;
60 pragma Preelaborable_Initialization
(Set
);
62 type Cursor
is private;
63 pragma Preelaborable_Initialization
(Cursor
);
65 Empty_Set
: constant Set
;
66 -- Set objects declared without an initialization expression are
67 -- initialized to the value Empty_Set.
69 No_Element
: constant Cursor
;
70 -- Cursor objects declared without an initialization expression are
71 -- initialized to the value No_Element.
73 function Has_Element
(Position
: Cursor
) return Boolean;
74 -- Equivalent to Position /= No_Element
76 package Set_Iterator_Interfaces
is new
77 Ada
.Iterator_Interfaces
(Cursor
, Has_Element
);
79 function "=" (Left
, Right
: Set
) return Boolean;
80 -- For each element in Left, set equality attempts to find the equal
81 -- element in Right; if a search fails, then set equality immediately
82 -- returns False. The search works by calling Hash to find the bucket in
83 -- the Right set that corresponds to the Left element. If the bucket is
84 -- non-empty, the search calls the generic formal element equality operator
85 -- to compare the element (in Left) to the element of each node in the
86 -- bucket (in Right); the search terminates when a matching node in the
87 -- bucket is found, or the nodes in the bucket are exhausted. (Note that
88 -- element equality is called here, not Equivalent_Elements. Set equality
89 -- is the only operation in which element equality is used. Compare set
90 -- equality to Equivalent_Sets, which does call Equivalent_Elements.)
92 function Equivalent_Sets
(Left
, Right
: Set
) return Boolean;
93 -- Similar to set equality, with the difference that the element in Left is
94 -- compared to the elements in Right using the generic formal
95 -- Equivalent_Elements operation instead of element equality.
97 function To_Set
(New_Item
: Element_Type
) return Set
;
98 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to
99 -- determine the bucket for New_Item.
101 function Capacity
(Container
: Set
) return Count_Type
;
102 -- Returns the current capacity of the set. Capacity is the maximum length
103 -- before which rehashing in guaranteed not to occur.
105 procedure Reserve_Capacity
(Container
: in out Set
; Capacity
: Count_Type
);
106 -- Adjusts the current capacity, by allocating a new buckets array. If the
107 -- requested capacity is less than the current capacity, then the capacity
108 -- is contracted (to a value not less than the current length). If the
109 -- requested capacity is greater than the current capacity, then the
110 -- capacity is expanded (to a value not less than what is requested). In
111 -- either case, the nodes are rehashed from the old buckets array onto the
112 -- new buckets array (Hash is called once for each existing element in
113 -- order to compute the new index), and then the old buckets array is
116 function Length
(Container
: Set
) return Count_Type
;
117 -- Returns the number of items in the set
119 function Is_Empty
(Container
: Set
) return Boolean;
120 -- Equivalent to Length (Container) = 0
122 procedure Clear
(Container
: in out Set
);
123 -- Removes all of the items from the set
125 function Element
(Position
: Cursor
) return Element_Type
;
126 -- Returns the element of the node designated by the cursor
128 procedure Replace_Element
129 (Container
: in out Set
;
131 New_Item
: Element_Type
);
132 -- If New_Item is equivalent (as determined by calling Equivalent_Elements)
133 -- to the element of the node designated by Position, then New_Element is
134 -- assigned to that element. Otherwise, it calls Hash to determine the
135 -- bucket for New_Item. If the bucket is not empty, then it calls
136 -- Equivalent_Elements for each node in that bucket to determine whether
137 -- New_Item is equivalent to an element in that bucket. If
138 -- Equivalent_Elements returns True then Program_Error is raised (because
139 -- an element may appear only once in the set); otherwise, New_Item is
140 -- assigned to the node designated by Position, and the node is moved to
143 procedure Query_Element
145 Process
: not null access procedure (Element
: Element_Type
));
146 -- Calls Process with the element (having only a constant view) of the node
147 -- designed by the cursor.
149 type Constant_Reference_Type
150 (Element
: not null access constant Element_Type
) is private
151 with Implicit_Dereference
=> Element
;
153 function Constant_Reference
154 (Container
: aliased Set
;
155 Position
: Cursor
) return Constant_Reference_Type
;
156 pragma Inline
(Constant_Reference
);
158 procedure Assign
(Target
: in out Set
; Source
: Set
);
160 function Copy
(Source
: Set
; Capacity
: Count_Type
:= 0) return Set
;
162 procedure Move
(Target
: in out Set
; Source
: in out Set
);
163 -- Clears Target (if it's not empty), and then moves (not copies) the
164 -- buckets array and nodes from Source to Target.
167 (Container
: in out Set
;
168 New_Item
: Element_Type
;
169 Position
: out Cursor
;
170 Inserted
: out Boolean);
171 -- Conditionally inserts New_Item into the set. If New_Item is already in
172 -- the set, then Inserted returns False and Position designates the node
173 -- containing the existing element (which is not modified). If New_Item is
174 -- not already in the set, then Inserted returns True and Position
175 -- designates the newly-inserted node containing New_Item. The search for
176 -- an existing element works as follows. Hash is called to determine
177 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements
178 -- is called to compare New_Item to the element of each node in that
179 -- bucket. If the bucket is empty, or there were no equivalent elements in
180 -- the bucket, the search "fails" and the New_Item is inserted in the set
181 -- (and Inserted returns True); otherwise, the search "succeeds" (and
182 -- Inserted returns False).
184 procedure Insert
(Container
: in out Set
; New_Item
: Element_Type
);
185 -- Attempts to insert New_Item into the set, performing the usual insertion
186 -- search (which involves calling both Hash and Equivalent_Elements); if
187 -- the search succeeds (New_Item is equivalent to an element already in the
188 -- set, and so was not inserted), then this operation raises
189 -- Constraint_Error. (This version of Insert is similar to Replace, but
190 -- having the opposite exception behavior. It is intended for use when you
191 -- want to assert that the item is not already in the set.)
193 procedure Include
(Container
: in out Set
; New_Item
: Element_Type
);
194 -- Attempts to insert New_Item into the set. If an element equivalent to
195 -- New_Item is already in the set (the insertion search succeeded, and
196 -- hence New_Item was not inserted), then the value of New_Item is assigned
197 -- to the existing element. (This insertion operation only raises an
198 -- exception if cursor tampering occurs. It is intended for use when you
199 -- want to insert the item in the set, and you don't care whether an
200 -- equivalent element is already present.)
202 procedure Replace
(Container
: in out Set
; New_Item
: Element_Type
);
203 -- Searches for New_Item in the set; if the search fails (because an
204 -- equivalent element was not in the set), then it raises
205 -- Constraint_Error. Otherwise, the existing element is assigned the value
206 -- New_Item. (This is similar to Insert, but with the opposite exception
207 -- behavior. It is intended for use when you want to assert that the item
208 -- is already in the set.)
210 procedure Exclude
(Container
: in out Set
; Item
: Element_Type
);
211 -- Searches for Item in the set, and if found, removes its node from the
212 -- set and then deallocates it. The search works as follows. The operation
213 -- calls Hash to determine the item's bucket; if the bucket is not empty,
214 -- it calls Equivalent_Elements to compare Item to the element of each node
215 -- in the bucket. (This is the deletion analog of Include. It is intended
216 -- for use when you want to remove the item from the set, but don't care
217 -- whether the item is already in the set.)
219 procedure Delete
(Container
: in out Set
; Item
: Element_Type
);
220 -- Searches for Item in the set (which involves calling both Hash and
221 -- Equivalent_Elements). If the search fails, then the operation raises
222 -- Constraint_Error. Otherwise it removes the node from the set and then
223 -- deallocates it. (This is the deletion analog of non-conditional
224 -- Insert. It is intended for use when you want to assert that the item is
225 -- already in the set.)
227 procedure Delete
(Container
: in out Set
; Position
: in out Cursor
);
228 -- Removes the node designated by Position from the set, and then
229 -- deallocates the node. The operation calls Hash to determine the bucket,
230 -- and then compares Position to each node in the bucket until there's a
231 -- match (it does not call Equivalent_Elements).
233 procedure Union
(Target
: in out Set
; Source
: Set
);
234 -- The operation first calls Reserve_Capacity if the current capacity is
235 -- less than the sum of the lengths of Source and Target. It then iterates
236 -- over the Source set, and conditionally inserts each element into Target.
238 function Union
(Left
, Right
: Set
) return Set
;
239 -- The operation first copies the Left set to the result, and then iterates
240 -- over the Right set to conditionally insert each element into the result.
242 function "or" (Left
, Right
: Set
) return Set
renames Union
;
244 procedure Intersection
(Target
: in out Set
; Source
: Set
);
245 -- Iterates over the Target set (calling First and Next), calling Find to
246 -- determine whether the element is in Source. If an equivalent element is
247 -- not found in Source, the element is deleted from Target.
249 function Intersection
(Left
, Right
: Set
) return Set
;
250 -- Iterates over the Left set, calling Find to determine whether the
251 -- element is in Right. If an equivalent element is found, it is inserted
252 -- into the result set.
254 function "and" (Left
, Right
: Set
) return Set
renames Intersection
;
256 procedure Difference
(Target
: in out Set
; Source
: Set
);
257 -- Iterates over the Source (calling First and Next), calling Find to
258 -- determine whether the element is in Target. If an equivalent element is
259 -- found, it is deleted from Target.
261 function Difference
(Left
, Right
: Set
) return Set
;
262 -- Iterates over the Left set, calling Find to determine whether the
263 -- element is in the Right set. If an equivalent element is not found, the
264 -- element is inserted into the result set.
266 function "-" (Left
, Right
: Set
) return Set
renames Difference
;
268 procedure Symmetric_Difference
(Target
: in out Set
; Source
: Set
);
269 -- The operation first calls Reserve_Capacity if the current capacity is
270 -- less than the sum of the lengths of Source and Target. It then iterates
271 -- over the Source set, searching for the element in Target (calling Hash
272 -- and Equivalent_Elements). If an equivalent element is found, it is
273 -- removed from Target; otherwise it is inserted into Target.
275 function Symmetric_Difference
(Left
, Right
: Set
) return Set
;
276 -- The operation first iterates over the Left set. It calls Find to
277 -- determine whether the element is in the Right set. If no equivalent
278 -- element is found, the element from Left is inserted into the result. The
279 -- operation then iterates over the Right set, to determine whether the
280 -- element is in the Left set. If no equivalent element is found, the Right
281 -- element is inserted into the result.
283 function "xor" (Left
, Right
: Set
) return Set
284 renames Symmetric_Difference
;
286 function Overlap
(Left
, Right
: Set
) return Boolean;
287 -- Iterates over the Left set (calling First and Next), calling Find to
288 -- determine whether the element is in the Right set. If an equivalent
289 -- element is found, the operation immediately returns True. The operation
290 -- returns False if the iteration over Left terminates without finding any
291 -- equivalent element in Right.
293 function Is_Subset
(Subset
: Set
; Of_Set
: Set
) return Boolean;
294 -- Iterates over Subset (calling First and Next), calling Find to determine
295 -- whether the element is in Of_Set. If no equivalent element is found in
296 -- Of_Set, the operation immediately returns False. The operation returns
297 -- True if the iteration over Subset terminates without finding an element
298 -- not in Of_Set (that is, every element in Subset is equivalent to an
299 -- element in Of_Set).
301 function First
(Container
: Set
) return Cursor
;
302 -- Returns a cursor that designates the first non-empty bucket, by
303 -- searching from the beginning of the buckets array.
305 function Next
(Position
: Cursor
) return Cursor
;
306 -- Returns a cursor that designates the node that follows the current one
307 -- designated by Position. If Position designates the last node in its
308 -- bucket, the operation calls Hash to compute the index of this bucket,
309 -- and searches the buckets array for the first non-empty bucket, starting
310 -- from that index; otherwise, it simply follows the link to the next node
311 -- in the same bucket.
313 procedure Next
(Position
: in out Cursor
);
314 -- Equivalent to Position := Next (Position)
318 Item
: Element_Type
) return Cursor
;
319 -- Searches for Item in the set. Find calls Hash to determine the item's
320 -- bucket; if the bucket is not empty, it calls Equivalent_Elements to
321 -- compare Item to each element in the bucket. If the search succeeds, Find
322 -- returns a cursor designating the node containing the equivalent element;
323 -- otherwise, it returns No_Element.
325 function Contains
(Container
: Set
; Item
: Element_Type
) return Boolean;
326 -- Equivalent to Find (Container, Item) /= No_Element
328 function Equivalent_Elements
(Left
, Right
: Cursor
) return Boolean;
329 -- Returns the result of calling Equivalent_Elements with the elements of
330 -- the nodes designated by cursors Left and Right.
332 function Equivalent_Elements
334 Right
: Element_Type
) return Boolean;
335 -- Returns the result of calling Equivalent_Elements with element of the
336 -- node designated by Left and element Right.
338 function Equivalent_Elements
339 (Left
: Element_Type
;
340 Right
: Cursor
) return Boolean;
341 -- Returns the result of calling Equivalent_Elements with element Left and
342 -- the element of the node designated by Right.
346 Process
: not null access procedure (Position
: Cursor
));
347 -- Calls Process for each node in the set
350 (Container
: Set
) return Set_Iterator_Interfaces
.Forward_Iterator
'Class;
353 type Key_Type
(<>) is private;
355 with function Key
(Element
: Element_Type
) return Key_Type
;
357 with function Hash
(Key
: Key_Type
) return Hash_Type
;
359 with function Equivalent_Keys
(Left
, Right
: Key_Type
) return Boolean;
361 package Generic_Keys
is
363 function Key
(Position
: Cursor
) return Key_Type
;
364 -- Applies generic formal operation Key to the element of the node
365 -- designated by Position.
367 function Element
(Container
: Set
; Key
: Key_Type
) return Element_Type
;
368 -- Searches (as per the key-based Find) for the node containing Key, and
369 -- returns the associated element.
372 (Container
: in out Set
;
374 New_Item
: Element_Type
);
375 -- Searches (as per the key-based Find) for the node containing Key, and
376 -- then replaces the element of that node (as per the element-based
379 procedure Exclude
(Container
: in out Set
; Key
: Key_Type
);
380 -- Searches for Key in the set, and if found, removes its node from the
381 -- set and then deallocates it. The search works by first calling Hash
382 -- (on Key) to determine the bucket; if the bucket is not empty, it
383 -- calls Equivalent_Keys to compare parameter Key to the value of
384 -- generic formal operation Key applied to element of each node in the
387 procedure Delete
(Container
: in out Set
; Key
: Key_Type
);
388 -- Deletes the node containing Key as per Exclude, with the difference
389 -- that Constraint_Error is raised if Key is not found.
391 function Find
(Container
: Set
; Key
: Key_Type
) return Cursor
;
392 -- Searches for the node containing Key, and returns a cursor
393 -- designating the node. The search works by first calling Hash (on Key)
394 -- to determine the bucket. If the bucket is not empty, the search
395 -- compares Key to the element of each node in the bucket, and returns
396 -- the matching node. The comparison itself works by applying the
397 -- generic formal Key operation to the element of the node, and then
398 -- calling generic formal operation Equivalent_Keys.
400 function Contains
(Container
: Set
; Key
: Key_Type
) return Boolean;
401 -- Equivalent to Find (Container, Key) /= No_Element
403 procedure Update_Element_Preserving_Key
404 (Container
: in out Set
;
406 Process
: not null access
407 procedure (Element
: in out Element_Type
));
408 -- Calls Process with the element of the node designated by Position,
409 -- but with the restriction that the key-value of the element is not
410 -- modified. The operation first makes a copy of the value returned by
411 -- applying generic formal operation Key on the element of the node, and
412 -- then calls Process with the element. The operation verifies that the
413 -- key-part has not been modified by calling generic formal operation
414 -- Equivalent_Keys to compare the saved key-value to the value returned
415 -- by applying generic formal operation Key to the post-Process value of
416 -- element. If the key values compare equal then the operation
417 -- completes. Otherwise, the node is removed from the set and
418 -- Program_Error is raised.
420 type Reference_Type
(Element
: not null access Element_Type
) is private
421 with Implicit_Dereference
=> Element
;
423 function Reference_Preserving_Key
424 (Container
: aliased in out Set
;
425 Position
: Cursor
) return Reference_Type
;
427 function Constant_Reference
428 (Container
: aliased Set
;
429 Key
: Key_Type
) return Constant_Reference_Type
;
431 function Reference_Preserving_Key
432 (Container
: aliased in out Set
;
433 Key
: Key_Type
) return Reference_Type
;
436 type Reference_Type
(Element
: not null access Element_Type
)
442 (Stream
: not null access Root_Stream_Type
'Class;
443 Item
: out Reference_Type
);
445 for Reference_Type
'Read use Read
;
448 (Stream
: not null access Root_Stream_Type
'Class;
449 Item
: Reference_Type
);
451 for Reference_Type
'Write use Write
;
456 pragma Inline
(Next
);
459 type Node_Access
is access Node_Type
;
461 type Node_Type
is limited record
462 Element
: aliased Element_Type
;
467 new Hash_Tables
.Generic_Hash_Table_Types
(Node_Type
, Node_Access
);
469 type Set
is new Ada
.Finalization
.Controlled
with record
470 HT
: HT_Types
.Hash_Table_Type
;
473 overriding
procedure Adjust
(Container
: in out Set
);
475 overriding
procedure Finalize
(Container
: in out Set
);
478 use Ada
.Finalization
;
482 (Stream
: not null access Root_Stream_Type
'Class;
485 for Set
'Write use Write
;
488 (Stream
: not null access Root_Stream_Type
'Class;
489 Container
: out Set
);
491 for Set
'Read use Read
;
493 type Set_Access
is access all Set
;
494 for Set_Access
'Storage_Size use 0;
496 type Cursor
is record
497 Container
: Set_Access
;
502 (Stream
: not null access Root_Stream_Type
'Class;
505 for Cursor
'Write use Write
;
508 (Stream
: not null access Root_Stream_Type
'Class;
511 for Cursor
'Read use Read
;
513 type Reference_Control_Type
is
514 new Controlled
with record
515 Container
: Set_Access
;
518 overriding
procedure Adjust
(Control
: in out Reference_Control_Type
);
519 pragma Inline
(Adjust
);
521 overriding
procedure Finalize
(Control
: in out Reference_Control_Type
);
522 pragma Inline
(Finalize
);
524 type Constant_Reference_Type
525 (Element
: not null access constant Element_Type
) is
527 Control
: Reference_Control_Type
;
531 (Stream
: not null access Root_Stream_Type
'Class;
532 Item
: out Constant_Reference_Type
);
534 for Constant_Reference_Type
'Read use Read
;
537 (Stream
: not null access Root_Stream_Type
'Class;
538 Item
: Constant_Reference_Type
);
540 for Constant_Reference_Type
'Write use Write
;
542 Empty_Set
: constant Set
:= (Controlled
with HT
=> (null, 0, 0, 0));
544 No_Element
: constant Cursor
:= (Container
=> null, Node
=> null);
546 end Ada
.Containers
.Hashed_Sets
;