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) 2004-2011, 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 private with Ada.Containers.Hash_Tables;
35 private with Ada.Streams;
36 private with Ada.Finalization;
37 with Ada.Iterator_Interfaces;
40 type Element_Type is private;
42 with function Hash (Element : Element_Type) return Hash_Type;
44 with function Equivalent_Elements
45 (Left, Right : Element_Type) return Boolean;
47 with function "=" (Left, Right : Element_Type) return Boolean is <>;
49 package Ada.Containers.Hashed_Sets is
53 type Set is tagged private
55 Default_Iterator => Iterate,
56 Iterator_Element => Element_Type;
58 pragma Preelaborable_Initialization (Set);
60 type Cursor is private;
61 pragma Preelaborable_Initialization (Cursor);
63 Empty_Set : constant Set;
64 -- Set objects declared without an initialization expression are
65 -- initialized to the value Empty_Set.
67 No_Element : constant Cursor;
68 -- Cursor objects declared without an initialization expression are
69 -- initialized to the value No_Element.
71 function Has_Element (Position : Cursor) return Boolean;
72 -- Equivalent to Position /= No_Element
74 package Set_Iterator_Interfaces is new
75 Ada.Iterator_Interfaces (Cursor, Has_Element);
77 function "=" (Left, Right : Set) return Boolean;
78 -- For each element in Left, set equality attempts to find the equal
79 -- element in Right; if a search fails, then set equality immediately
80 -- returns False. The search works by calling Hash to find the bucket in
81 -- the Right set that corresponds to the Left element. If the bucket is
82 -- non-empty, the search calls the generic formal element equality operator
83 -- to compare the element (in Left) to the element of each node in the
84 -- bucket (in Right); the search terminates when a matching node in the
85 -- bucket is found, or the nodes in the bucket are exhausted. (Note that
86 -- element equality is called here, not Equivalent_Elements. Set equality
87 -- is the only operation in which element equality is used. Compare set
88 -- equality to Equivalent_Sets, which does call Equivalent_Elements.)
90 function Equivalent_Sets (Left, Right : Set) return Boolean;
91 -- Similar to set equality, with the difference that the element in Left is
92 -- compared to the elements in Right using the generic formal
93 -- Equivalent_Elements operation instead of element equality.
95 function To_Set (New_Item : Element_Type) return Set;
96 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to
97 -- determine the bucket for New_Item.
99 function Capacity (Container : Set) return Count_Type;
100 -- Returns the current capacity of the set. Capacity is the maximum length
101 -- before which rehashing in guaranteed not to occur.
103 procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type);
104 -- Adjusts the current capacity, by allocating a new buckets array. If the
105 -- requested capacity is less than the current capacity, then the capacity
106 -- is contracted (to a value not less than the current length). If the
107 -- requested capacity is greater than the current capacity, then the
108 -- capacity is expanded (to a value not less than what is requested). In
109 -- either case, the nodes are rehashed from the old buckets array onto the
110 -- new buckets array (Hash is called once for each existing element in
111 -- order to compute the new index), and then the old buckets array is
114 function Length (Container : Set) return Count_Type;
115 -- Returns the number of items in the set
117 function Is_Empty (Container : Set) return Boolean;
118 -- Equivalent to Length (Container) = 0
120 procedure Clear (Container : in out Set);
121 -- Removes all of the items from the set
123 function Element (Position : Cursor) return Element_Type;
124 -- Returns the element of the node designated by the cursor
126 procedure Replace_Element
127 (Container : in out Set;
129 New_Item : Element_Type);
130 -- If New_Item is equivalent (as determined by calling Equivalent_Elements)
131 -- to the element of the node designated by Position, then New_Element is
132 -- assigned to that element. Otherwise, it calls Hash to determine the
133 -- bucket for New_Item. If the bucket is not empty, then it calls
134 -- Equivalent_Elements for each node in that bucket to determine whether
135 -- New_Item is equivalent to an element in that bucket. If
136 -- Equivalent_Elements returns True then Program_Error is raised (because
137 -- an element may appear only once in the set); otherwise, New_Item is
138 -- assigned to the node designated by Position, and the node is moved to
141 procedure Query_Element
143 Process : not null access procedure (Element : Element_Type));
144 -- Calls Process with the element (having only a constant view) of the node
145 -- designed by the cursor.
147 procedure Assign (Target : in out Set; Source : Set);
149 function Copy (Source : Set; Capacity : Count_Type := 0) return Set;
151 procedure Move (Target : in out Set; Source : in out Set);
152 -- Clears Target (if it's not empty), and then moves (not copies) the
153 -- buckets array and nodes from Source to Target.
156 (Container : in out Set;
157 New_Item : Element_Type;
158 Position : out Cursor;
159 Inserted : out Boolean);
160 -- Conditionally inserts New_Item into the set. If New_Item is already in
161 -- the set, then Inserted returns False and Position designates the node
162 -- containing the existing element (which is not modified). If New_Item is
163 -- not already in the set, then Inserted returns True and Position
164 -- designates the newly-inserted node containing New_Item. The search for
165 -- an existing element works as follows. Hash is called to determine
166 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements
167 -- is called to compare New_Item to the element of each node in that
168 -- bucket. If the bucket is empty, or there were no equivalent elements in
169 -- the bucket, the search "fails" and the New_Item is inserted in the set
170 -- (and Inserted returns True); otherwise, the search "succeeds" (and
171 -- Inserted returns False).
173 procedure Insert (Container : in out Set; New_Item : Element_Type);
174 -- Attempts to insert New_Item into the set, performing the usual insertion
175 -- search (which involves calling both Hash and Equivalent_Elements); if
176 -- the search succeeds (New_Item is equivalent to an element already in the
177 -- set, and so was not inserted), then this operation raises
178 -- Constraint_Error. (This version of Insert is similar to Replace, but
179 -- having the opposite exception behavior. It is intended for use when you
180 -- want to assert that the item is not already in the set.)
182 procedure Include (Container : in out Set; New_Item : Element_Type);
183 -- Attempts to insert New_Item into the set. If an element equivalent to
184 -- New_Item is already in the set (the insertion search succeeded, and
185 -- hence New_Item was not inserted), then the value of New_Item is assigned
186 -- to the existing element. (This insertion operation only raises an
187 -- exception if cursor tampering occurs. It is intended for use when you
188 -- want to insert the item in the set, and you don't care whether an
189 -- equivalent element is already present.)
191 procedure Replace (Container : in out Set; New_Item : Element_Type);
192 -- Searches for New_Item in the set; if the search fails (because an
193 -- equivalent element was not in the set), then it raises
194 -- Constraint_Error. Otherwise, the existing element is assigned the value
195 -- New_Item. (This is similar to Insert, but with the opposite exception
196 -- behavior. It is intended for use when you want to assert that the item
197 -- is already in the set.)
199 procedure Exclude (Container : in out Set; Item : Element_Type);
200 -- Searches for Item in the set, and if found, removes its node from the
201 -- set and then deallocates it. The search works as follows. The operation
202 -- calls Hash to determine the item's bucket; if the bucket is not empty,
203 -- it calls Equivalent_Elements to compare Item to the element of each node
204 -- in the bucket. (This is the deletion analog of Include. It is intended
205 -- for use when you want to remove the item from the set, but don't care
206 -- whether the item is already in the set.)
208 procedure Delete (Container : in out Set; Item : Element_Type);
209 -- Searches for Item in the set (which involves calling both Hash and
210 -- Equivalent_Elements). If the search fails, then the operation raises
211 -- Constraint_Error. Otherwise it removes the node from the set and then
212 -- deallocates it. (This is the deletion analog of non-conditional
213 -- Insert. It is intended for use when you want to assert that the item is
214 -- already in the set.)
216 procedure Delete (Container : in out Set; Position : in out Cursor);
217 -- Removes the node designated by Position from the set, and then
218 -- deallocates the node. The operation calls Hash to determine the bucket,
219 -- and then compares Position to each node in the bucket until there's a
220 -- match (it does not call Equivalent_Elements).
222 procedure Union (Target : in out Set; Source : Set);
223 -- The operation first calls Reserve_Capacity if the current capacity is
224 -- less than the sum of the lengths of Source and Target. It then iterates
225 -- over the Source set, and conditionally inserts each element into Target.
227 function Union (Left, Right : Set) return Set;
228 -- The operation first copies the Left set to the result, and then iterates
229 -- over the Right set to conditionally insert each element into the result.
231 function "or" (Left, Right : Set) return Set renames Union;
233 procedure Intersection (Target : in out Set; Source : Set);
234 -- Iterates over the Target set (calling First and Next), calling Find to
235 -- determine whether the element is in Source. If an equivalent element is
236 -- not found in Source, the element is deleted from Target.
238 function Intersection (Left, Right : Set) return Set;
239 -- Iterates over the Left set, calling Find to determine whether the
240 -- element is in Right. If an equivalent element is found, it is inserted
241 -- into the result set.
243 function "and" (Left, Right : Set) return Set renames Intersection;
245 procedure Difference (Target : in out Set; Source : Set);
246 -- Iterates over the Source (calling First and Next), calling Find to
247 -- determine whether the element is in Target. If an equivalent element is
248 -- found, it is deleted from Target.
250 function Difference (Left, Right : Set) return Set;
251 -- Iterates over the Left set, calling Find to determine whether the
252 -- element is in the Right set. If an equivalent element is not found, the
253 -- element is inserted into the result set.
255 function "-" (Left, Right : Set) return Set renames Difference;
257 procedure Symmetric_Difference (Target : in out Set; Source : Set);
258 -- The operation first calls Reserve_Capacity if the current capacity is
259 -- less than the sum of the lengths of Source and Target. It then iterates
260 -- over the Source set, searching for the element in Target (calling Hash
261 -- and Equivalent_Elements). If an equivalent element is found, it is
262 -- removed from Target; otherwise it is inserted into Target.
264 function Symmetric_Difference (Left, Right : Set) return Set;
265 -- The operation first iterates over the Left set. It calls Find to
266 -- determine whether the element is in the Right set. If no equivalent
267 -- element is found, the element from Left is inserted into the result. The
268 -- operation then iterates over the Right set, to determine whether the
269 -- element is in the Left set. If no equivalent element is found, the Right
270 -- element is inserted into the result.
272 function "xor" (Left, Right : Set) return Set
273 renames Symmetric_Difference;
275 function Overlap (Left, Right : Set) return Boolean;
276 -- Iterates over the Left set (calling First and Next), calling Find to
277 -- determine whether the element is in the Right set. If an equivalent
278 -- element is found, the operation immediately returns True. The operation
279 -- returns False if the iteration over Left terminates without finding any
280 -- equivalent element in Right.
282 function Is_Subset (Subset : Set; Of_Set : Set) return Boolean;
283 -- Iterates over Subset (calling First and Next), calling Find to determine
284 -- whether the element is in Of_Set. If no equivalent element is found in
285 -- Of_Set, the operation immediately returns False. The operation returns
286 -- True if the iteration over Subset terminates without finding an element
287 -- not in Of_Set (that is, every element in Subset is equivalent to an
288 -- element in Of_Set).
290 function First (Container : Set) return Cursor;
291 -- Returns a cursor that designates the first non-empty bucket, by
292 -- searching from the beginning of the buckets array.
294 function Next (Position : Cursor) return Cursor;
295 -- Returns a cursor that designates the node that follows the current one
296 -- designated by Position. If Position designates the last node in its
297 -- bucket, the operation calls Hash to compute the index of this bucket,
298 -- and searches the buckets array for the first non-empty bucket, starting
299 -- from that index; otherwise, it simply follows the link to the next node
300 -- in the same bucket.
302 procedure Next (Position : in out Cursor);
303 -- Equivalent to Position := Next (Position)
307 Item : Element_Type) return Cursor;
308 -- Searches for Item in the set. Find calls Hash to determine the item's
309 -- bucket; if the bucket is not empty, it calls Equivalent_Elements to
310 -- compare Item to each element in the bucket. If the search succeeds, Find
311 -- returns a cursor designating the node containing the equivalent element;
312 -- otherwise, it returns No_Element.
314 function Contains (Container : Set; Item : Element_Type) return Boolean;
315 -- Equivalent to Find (Container, Item) /= No_Element
317 function Equivalent_Elements (Left, Right : Cursor) return Boolean;
318 -- Returns the result of calling Equivalent_Elements with the elements of
319 -- the nodes designated by cursors Left and Right.
321 function Equivalent_Elements
323 Right : Element_Type) return Boolean;
324 -- Returns the result of calling Equivalent_Elements with element of the
325 -- node designated by Left and element Right.
327 function Equivalent_Elements
328 (Left : Element_Type;
329 Right : Cursor) return Boolean;
330 -- Returns the result of calling Equivalent_Elements with element Left and
331 -- the element of the node designated by Right.
335 Process : not null access procedure (Position : Cursor));
336 -- Calls Process for each node in the set
339 (Container : Set) return Set_Iterator_Interfaces.Forward_Iterator'Class;
342 type Key_Type (<>) is private;
344 with function Key (Element : Element_Type) return Key_Type;
346 with function Hash (Key : Key_Type) return Hash_Type;
348 with function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
350 package Generic_Keys is
352 function Key (Position : Cursor) return Key_Type;
353 -- Applies generic formal operation Key to the element of the node
354 -- designated by Position.
356 function Element (Container : Set; Key : Key_Type) return Element_Type;
357 -- Searches (as per the key-based Find) for the node containing Key, and
358 -- returns the associated element.
361 (Container : in out Set;
363 New_Item : Element_Type);
364 -- Searches (as per the key-based Find) for the node containing Key, and
365 -- then replaces the element of that node (as per the element-based
368 procedure Exclude (Container : in out Set; Key : Key_Type);
369 -- Searches for Key in the set, and if found, removes its node from the
370 -- set and then deallocates it. The search works by first calling Hash
371 -- (on Key) to determine the bucket; if the bucket is not empty, it
372 -- calls Equivalent_Keys to compare parameter Key to the value of
373 -- generic formal operation Key applied to element of each node in the
376 procedure Delete (Container : in out Set; Key : Key_Type);
377 -- Deletes the node containing Key as per Exclude, with the difference
378 -- that Constraint_Error is raised if Key is not found.
380 function Find (Container : Set; Key : Key_Type) return Cursor;
381 -- Searches for the node containing Key, and returns a cursor
382 -- designating the node. The search works by first calling Hash (on Key)
383 -- to determine the bucket. If the bucket is not empty, the search
384 -- compares Key to the element of each node in the bucket, and returns
385 -- the matching node. The comparison itself works by applying the
386 -- generic formal Key operation to the element of the node, and then
387 -- calling generic formal operation Equivalent_Keys.
389 function Contains (Container : Set; Key : Key_Type) return Boolean;
390 -- Equivalent to Find (Container, Key) /= No_Element
392 procedure Update_Element_Preserving_Key
393 (Container : in out Set;
395 Process : not null access
396 procedure (Element : in out Element_Type));
397 -- Calls Process with the element of the node designated by Position,
398 -- but with the restriction that the key-value of the element is not
399 -- modified. The operation first makes a copy of the value returned by
400 -- applying generic formal operation Key on the element of the node, and
401 -- then calls Process with the element. The operation verifies that the
402 -- key-part has not been modified by calling generic formal operation
403 -- Equivalent_Keys to compare the saved key-value to the value returned
404 -- by applying generic formal operation Key to the post-Process value of
405 -- element. If the key values compare equal then the operation
406 -- completes. Otherwise, the node is removed from the map and
407 -- Program_Error is raised.
413 pragma Inline (Next);
416 type Node_Access is access Node_Type;
418 type Node_Type is limited record
419 Element : Element_Type;
424 new Hash_Tables.Generic_Hash_Table_Types (Node_Type, Node_Access);
426 type Set is new Ada.Finalization.Controlled with record
427 HT : HT_Types.Hash_Table_Type;
430 overriding procedure Adjust (Container : in out Set);
432 overriding procedure Finalize (Container : in out Set);
435 use Ada.Finalization;
438 type Set_Access is access all Set;
439 for Set_Access'Storage_Size use 0;
441 type Cursor is record
442 Container : Set_Access;
447 (Stream : not null access Root_Stream_Type'Class;
450 for Cursor'Write use Write;
453 (Stream : not null access Root_Stream_Type'Class;
456 for Cursor'Read use Read;
458 No_Element : constant Cursor := (Container => null, Node => null);
461 (Stream : not null access Root_Stream_Type'Class;
464 for Set'Write use Write;
467 (Stream : not null access Root_Stream_Type'Class;
468 Container : out Set);
470 for Set'Read use Read;
472 Empty_Set : constant Set := (Controlled with HT => (null, 0, 0, 0));
474 end Ada.Containers.Hashed_Sets;