1 ------------------------------------------------------------------------------
3 -- GNAT LIBRARY COMPONENTS --
5 -- ADA.CONTAINERS.INDEFINITE_HASHED_SETS --
9 -- Copyright (C) 2004-2008, 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 2, 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. See the GNU General Public License --
21 -- for more details. You should have received a copy of the GNU General --
22 -- Public License distributed with GNAT; see file COPYING. If not, write --
23 -- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
24 -- Boston, MA 02110-1301, USA. --
26 -- As a special exception, if other files instantiate generics from this --
27 -- unit, or you link this unit with other files to produce an executable, --
28 -- this unit does not by itself cause the resulting executable to be --
29 -- covered by the GNU General Public License. This exception does not --
30 -- however invalidate any other reasons why the executable file might be --
31 -- covered by the GNU Public License. --
33 -- This unit was originally developed by Matthew J Heaney. --
34 ------------------------------------------------------------------------------
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 (Left, Right : Element_Type)
48 with function "=" (Left, Right : Element_Type) return Boolean is <>;
50 package Ada.Containers.Indefinite_Hashed_Sets is
54 type Set is tagged private;
55 pragma Preelaborable_Initialization (Set);
57 type Cursor is private;
58 pragma Preelaborable_Initialization (Cursor);
60 Empty_Set : constant Set;
61 -- Set objects declared without an initialization expression are
62 -- initialized to the value Empty_Set.
64 No_Element : constant Cursor;
65 -- Cursor objects declared without an initialization expression are
66 -- initialized to the value No_Element.
68 function "=" (Left, Right : Set) return Boolean;
69 -- For each element in Left, set equality attempts to find the equal
70 -- element in Right; if a search fails, then set equality immediately
71 -- returns False. The search works by calling Hash to find the bucket in
72 -- the Right set that corresponds to the Left element. If the bucket is
73 -- non-empty, the search calls the generic formal element equality operator
74 -- to compare the element (in Left) to the element of each node in the
75 -- bucket (in Right); the search terminates when a matching node in the
76 -- bucket is found, or the nodes in the bucket are exhausted. (Note that
77 -- element equality is called here, not Equivalent_Elements. Set equality
78 -- is the only operation in which element equality is used. Compare set
79 -- equality to Equivalent_Sets, which does call Equivalent_Elements.)
81 function Equivalent_Sets (Left, Right : Set) return Boolean;
82 -- Similar to set equality, with the difference that the element in Left is
83 -- compared to the elements in Right using the generic formal
84 -- Equivalent_Elements operation instead of element equality.
86 function To_Set (New_Item : Element_Type) return Set;
87 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to
88 -- determine the bucket for New_Item.
90 function Capacity (Container : Set) return Count_Type;
91 -- Returns the current capacity of the set. Capacity is the maximum length
92 -- before which rehashing in guaranteed not to occur.
94 procedure Reserve_Capacity (Container : in out Set; Capacity : Count_Type);
95 -- Adjusts the current capacity, by allocating a new buckets array. If the
96 -- requested capacity is less than the current capacity, then the capacity
97 -- is contracted (to a value not less than the current length). If the
98 -- requested capacity is greater than the current capacity, then the
99 -- capacity is expanded (to a value not less than what is requested). In
100 -- either case, the nodes are rehashed from the old buckets array onto the
101 -- new buckets array (Hash is called once for each existing element in
102 -- order to compute the new index), and then the old buckets array is
105 function Length (Container : Set) return Count_Type;
106 -- Returns the number of items in the set
108 function Is_Empty (Container : Set) return Boolean;
109 -- Equivalent to Length (Container) = 0
111 procedure Clear (Container : in out Set);
112 -- Removes all of the items from the set
114 function Element (Position : Cursor) return Element_Type;
115 -- Returns the element of the node designated by the cursor
117 procedure Replace_Element
118 (Container : in out Set;
120 New_Item : Element_Type);
121 -- If New_Item is equivalent (as determined by calling Equivalent_Elements)
122 -- to the element of the node designated by Position, then New_Element is
123 -- assigned to that element. Otherwise, it calls Hash to determine the
124 -- bucket for New_Item. If the bucket is not empty, then it calls
125 -- Equivalent_Elements for each node in that bucket to determine whether
126 -- New_Item is equivalent to an element in that bucket. If
127 -- Equivalent_Elements returns True then Program_Error is raised (because
128 -- an element may appear only once in the set); otherwise, New_Item is
129 -- assigned to the node designated by Position, and the node is moved to
132 procedure Query_Element
134 Process : not null access procedure (Element : Element_Type));
135 -- Calls Process with the element (having only a constant view) of the node
136 -- designed by the cursor.
138 procedure Move (Target : in out Set; Source : in out Set);
139 -- Clears Target (if it's not empty), and then moves (not copies) the
140 -- buckets array and nodes from Source to Target.
143 (Container : in out Set;
144 New_Item : Element_Type;
145 Position : out Cursor;
146 Inserted : out Boolean);
147 -- Conditionally inserts New_Item into the set. If New_Item is already in
148 -- the set, then Inserted returns False and Position designates the node
149 -- containing the existing element (which is not modified). If New_Item is
150 -- not already in the set, then Inserted returns True and Position
151 -- designates the newly-inserted node containing New_Item. The search for
152 -- an existing element works as follows. Hash is called to determine
153 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements
154 -- is called to compare New_Item to the element of each node in that
155 -- bucket. If the bucket is empty, or there were no equivalent elements in
156 -- the bucket, the search "fails" and the New_Item is inserted in the set
157 -- (and Inserted returns True); otherwise, the search "succeeds" (and
158 -- Inserted returns False).
160 procedure Insert (Container : in out Set; New_Item : Element_Type);
161 -- Attempts to insert New_Item into the set, performing the usual insertion
162 -- search (which involves calling both Hash and Equivalent_Elements); if
163 -- the search succeeds (New_Item is equivalent to an element already in the
164 -- set, and so was not inserted), then this operation raises
165 -- Constraint_Error. (This version of Insert is similar to Replace, but
166 -- having the opposite exception behavior. It is intended for use when you
167 -- want to assert that the item is not already in the set.)
169 procedure Include (Container : in out Set; New_Item : Element_Type);
170 -- Attempts to insert New_Item into the set. If an element equivalent to
171 -- New_Item is already in the set (the insertion search succeeded, and
172 -- hence New_Item was not inserted), then the value of New_Item is assigned
173 -- to the existing element. (This insertion operation only raises an
174 -- exception if cursor tampering occurs. It is intended for use when you
175 -- want to insert the item in the set, and you don't care whether an
176 -- equivalent element is already present.)
178 procedure Replace (Container : in out Set; New_Item : Element_Type);
179 -- Searches for New_Item in the set; if the search fails (because an
180 -- equivalent element was not in the set), then it raises
181 -- Constraint_Error. Otherwise, the existing element is assigned the value
182 -- New_Item. (This is similar to Insert, but with the opposite exception
183 -- behavior. It is intended for use when you want to assert that the item
184 -- is already in the set.)
186 procedure Exclude (Container : in out Set; Item : Element_Type);
187 -- Searches for Item in the set, and if found, removes its node from the
188 -- set and then deallocates it. The search works as follows. The operation
189 -- calls Hash to determine the item's bucket; if the bucket is not empty,
190 -- it calls Equivalent_Elements to compare Item to the element of each node
191 -- in the bucket. (This is the deletion analog of Include. It is intended
192 -- for use when you want to remove the item from the set, but don't care
193 -- whether the item is already in the set.)
195 procedure Delete (Container : in out Set; Item : Element_Type);
196 -- Searches for Item in the set (which involves calling both Hash and
197 -- Equivalent_Elements). If the search fails, then the operation raises
198 -- Constraint_Error. Otherwise it removes the node from the set and then
199 -- deallocates it. (This is the deletion analog of non-conditional
200 -- Insert. It is intended for use when you want to assert that the item is
201 -- already in the set.)
203 procedure Delete (Container : in out Set; Position : in out Cursor);
204 -- Removes the node designated by Position from the set, and then
205 -- deallocates the node. The operation calls Hash to determine the bucket,
206 -- and then compares Position to each node in the bucket until there's a
207 -- match (it does not call Equivalent_Elements).
209 procedure Union (Target : in out Set; Source : Set);
210 -- The operation first calls Reserve_Capacity if the current capacity is
211 -- less than the sum of the lengths of Source and Target. It then iterates
212 -- over the Source set, and conditionally inserts each element into Target.
214 function Union (Left, Right : Set) return Set;
215 -- The operation first copies the Left set to the result, and then iterates
216 -- over the Right set to conditionally insert each element into the result.
218 function "or" (Left, Right : Set) return Set renames Union;
220 procedure Intersection (Target : in out Set; Source : Set);
221 -- Iterates over the Target set (calling First and Next), calling Find to
222 -- determine whether the element is in Source. If an equivalent element is
223 -- not found in Source, the element is deleted from Target.
225 function Intersection (Left, Right : Set) return Set;
226 -- Iterates over the Left set, calling Find to determine whether the
227 -- element is in Right. If an equivalent element is found, it is inserted
228 -- into the result set.
230 function "and" (Left, Right : Set) return Set renames Intersection;
232 procedure Difference (Target : in out Set; Source : Set);
233 -- Iterates over the Source (calling First and Next), calling Find to
234 -- determine whether the element is in Target. If an equivalent element is
235 -- found, it is deleted from Target.
237 function Difference (Left, Right : Set) return Set;
238 -- Iterates over the Left set, calling Find to determine whether the
239 -- element is in the Right set. If an equivalent element is not found, the
240 -- element is inserted into the result set.
242 function "-" (Left, Right : Set) return Set renames Difference;
244 procedure Symmetric_Difference (Target : in out Set; Source : Set);
245 -- The operation first calls Reserve_Capacity if the current capacity is
246 -- less than the sum of the lengths of Source and Target. It then iterates
247 -- over the Source set, searching for the element in Target (calling Hash
248 -- and Equivalent_Elements). If an equivalent element is found, it is
249 -- removed from Target; otherwise it is inserted into Target.
251 function Symmetric_Difference (Left, Right : Set) return Set;
252 -- The operation first iterates over the Left set. It calls Find to
253 -- determine whether the element is in the Right set. If no equivalent
254 -- element is found, the element from Left is inserted into the result. The
255 -- operation then iterates over the Right set, to determine whether the
256 -- element is in the Left set. If no equivalent element is found, the Right
257 -- element is inserted into the result.
259 function "xor" (Left, Right : Set) return Set
260 renames Symmetric_Difference;
262 function Overlap (Left, Right : Set) return Boolean;
263 -- Iterates over the Left set (calling First and Next), calling Find to
264 -- determine whether the element is in the Right set. If an equivalent
265 -- element is found, the operation immediately returns True. The operation
266 -- returns False if the iteration over Left terminates without finding any
267 -- equivalent element in Right.
269 function Is_Subset (Subset : Set; Of_Set : Set) return Boolean;
270 -- Iterates over Subset (calling First and Next), calling Find to determine
271 -- whether the element is in Of_Set. If no equivalent element is found in
272 -- Of_Set, the operation immediately returns False. The operation returns
273 -- True if the iteration over Subset terminates without finding an element
274 -- not in Of_Set (that is, every element in Subset is equivalent to an
275 -- element in Of_Set).
277 function First (Container : Set) return Cursor;
278 -- Returns a cursor that designates the first non-empty bucket, by
279 -- searching from the beginning of the buckets array.
281 function Next (Position : Cursor) return Cursor;
282 -- Returns a cursor that designates the node that follows the current one
283 -- designated by Position. If Position designates the last node in its
284 -- bucket, the operation calls Hash to compute the index of this bucket,
285 -- and searches the buckets array for the first non-empty bucket, starting
286 -- from that index; otherwise, it simply follows the link to the next node
287 -- in the same bucket.
289 procedure Next (Position : in out Cursor);
290 -- Equivalent to Position := Next (Position)
292 function Find (Container : Set; Item : Element_Type) return Cursor;
293 -- Searches for Item in the set. Find calls Hash to determine the item's
294 -- bucket; if the bucket is not empty, it calls Equivalent_Elements to
295 -- compare Item to each element in the bucket. If the search succeeds, Find
296 -- returns a cursor designating the node containing the equivalent element;
297 -- otherwise, it returns No_Element.
299 function Contains (Container : Set; Item : Element_Type) return Boolean;
300 -- Equivalent to Find (Container, Item) /= No_Element
302 function Has_Element (Position : Cursor) return Boolean;
303 -- Equivalent to Position /= No_Element
305 function Equivalent_Elements (Left, Right : Cursor) return Boolean;
306 -- Returns the result of calling Equivalent_Elements with the elements of
307 -- the nodes designated by cursors Left and Right.
309 function Equivalent_Elements
311 Right : Element_Type) return Boolean;
312 -- Returns the result of calling Equivalent_Elements with element of the
313 -- node designated by Left and element Right.
315 function Equivalent_Elements
316 (Left : Element_Type;
317 Right : Cursor) return Boolean;
318 -- Returns the result of calling Equivalent_Elements with element Left and
319 -- the element of the node designated by Right.
323 Process : not null access procedure (Position : Cursor));
324 -- Calls Process for each node in the set
327 type Key_Type (<>) is private;
329 with function Key (Element : Element_Type) return Key_Type;
331 with function Hash (Key : Key_Type) return Hash_Type;
333 with function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
335 package Generic_Keys is
337 function Key (Position : Cursor) return Key_Type;
338 -- Applies generic formal operation Key to the element of the node
339 -- designated by Position.
341 function Element (Container : Set; Key : Key_Type) return Element_Type;
342 -- Searches (as per the key-based Find) for the node containing Key, and
343 -- returns the associated element.
346 (Container : in out Set;
348 New_Item : Element_Type);
349 -- Searches (as per the key-based Find) for the node containing Key, and
350 -- then replaces the element of that node (as per the element-based
353 procedure Exclude (Container : in out Set; Key : Key_Type);
354 -- Searches for Key in the set, and if found, removes its node from the
355 -- set and then deallocates it. The search works by first calling Hash
356 -- (on Key) to determine the bucket; if the bucket is not empty, it
357 -- calls Equivalent_Keys to compare parameter Key to the value of
358 -- generic formal operation Key applied to element of each node in the
361 procedure Delete (Container : in out Set; Key : Key_Type);
362 -- Deletes the node containing Key as per Exclude, with the difference
363 -- that Constraint_Error is raised if Key is not found.
365 function Find (Container : Set; Key : Key_Type) return Cursor;
366 -- Searches for the node containing Key, and returns a cursor
367 -- designating the node. The search works by first calling Hash (on Key)
368 -- to determine the bucket. If the bucket is not empty, the search
369 -- compares Key to the element of each node in the bucket, and returns
370 -- the matching node. The comparison itself works by applying the
371 -- generic formal Key operation to the element of the node, and then
372 -- calling generic formal operation Equivalent_Keys.
374 function Contains (Container : Set; Key : Key_Type) return Boolean;
375 -- Equivalent to Find (Container, Key) /= No_Element
377 procedure Update_Element_Preserving_Key
378 (Container : in out Set;
380 Process : not null access
381 procedure (Element : in out Element_Type));
382 -- Calls Process with the element of the node designated by Position,
383 -- but with the restriction that the key-value of the element is not
384 -- modified. The operation first makes a copy of the value returned by
385 -- applying generic formal operation Key on the element of the node, and
386 -- then calls Process with the element. The operation verifies that the
387 -- key-part has not been modified by calling generic formal operation
388 -- Equivalent_Keys to compare the saved key-value to the value returned
389 -- by applying generic formal operation Key to the post-Process value of
390 -- element. If the key values compare equal then the operation
391 -- completes. Otherwise, the node is removed from the map and
392 -- Program_Error is raised.
398 pragma Inline (Next);
401 type Node_Access is access Node_Type;
403 type Element_Access is access Element_Type;
407 Element : Element_Access;
411 package HT_Types is new Hash_Tables.Generic_Hash_Table_Types
415 type Set is new Ada.Finalization.Controlled with record
416 HT : HT_Types.Hash_Table_Type;
420 procedure Adjust (Container : in out Set);
423 procedure Finalize (Container : in out Set);
426 use Ada.Finalization;
429 type Set_Access is access all Set;
430 for Set_Access'Storage_Size use 0;
434 Container : Set_Access;
439 (Stream : not null access Root_Stream_Type'Class;
442 for Cursor'Write use Write;
445 (Stream : not null access Root_Stream_Type'Class;
448 for Cursor'Read use Read;
450 No_Element : constant Cursor :=
455 (Stream : not null access Root_Stream_Type'Class;
458 for Set'Write use Write;
461 (Stream : not null access Root_Stream_Type'Class;
462 Container : out Set);
464 for Set'Read use Read;
466 Empty_Set : constant Set := (Controlled with HT => (null, 0, 0, 0));
468 end Ada.Containers.Indefinite_Hashed_Sets;