1 ------------------------------------------------------------------------------
3 -- GNAT LIBRARY COMPONENTS --
5 -- A D A . C O N T A I N E R S . B O U N D E D _ H A S H E D _ S E T S --
9 -- Copyright (C) 2004-2010, 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
;
38 type Element_Type
is private;
40 with function Hash
(Element
: Element_Type
) return Hash_Type
;
42 with function Equivalent_Elements
43 (Left
, Right
: Element_Type
) return Boolean;
45 with function "=" (Left
, Right
: Element_Type
) return Boolean is <>;
47 package Ada
.Containers
.Bounded_Hashed_Sets
is
51 type Set
(Capacity
: Count_Type
; Modulus
: Hash_Type
) is tagged private;
52 pragma Preelaborable_Initialization
(Set
);
54 type Cursor
is private;
55 pragma Preelaborable_Initialization
(Cursor
);
57 Empty_Set
: constant Set
;
58 -- Set objects declared without an initialization expression are
59 -- initialized to the value Empty_Set.
61 No_Element
: constant Cursor
;
62 -- Cursor objects declared without an initialization expression are
63 -- initialized to the value No_Element.
65 function "=" (Left
, Right
: Set
) return Boolean;
66 -- For each element in Left, set equality attempts to find the equal
67 -- element in Right; if a search fails, then set equality immediately
68 -- returns False. The search works by calling Hash to find the bucket in
69 -- the Right set that corresponds to the Left element. If the bucket is
70 -- non-empty, the search calls the generic formal element equality operator
71 -- to compare the element (in Left) to the element of each node in the
72 -- bucket (in Right); the search terminates when a matching node in the
73 -- bucket is found, or the nodes in the bucket are exhausted. (Note that
74 -- element equality is called here, not Equivalent_Elements. Set equality
75 -- is the only operation in which element equality is used. Compare set
76 -- equality to Equivalent_Sets, which does call Equivalent_Elements.)
78 function Equivalent_Sets
(Left
, Right
: Set
) return Boolean;
79 -- Similar to set equality, with the difference that the element in Left is
80 -- compared to the elements in Right using the generic formal
81 -- Equivalent_Elements operation instead of element equality.
83 function To_Set
(New_Item
: Element_Type
) return Set
;
84 -- Constructs a singleton set comprising New_Element. To_Set calls Hash to
85 -- determine the bucket for New_Item.
87 function Capacity
(Container
: Set
) return Count_Type
;
88 -- Returns the current capacity of the set. Capacity is the maximum length
89 -- before which rehashing in guaranteed not to occur.
91 procedure Reserve_Capacity
(Container
: in out Set
; Capacity
: Count_Type
);
92 -- If the value of the Capacity actual parameter is less or equal to
93 -- Container.Capacity, then the operation has no effect. Otherwise it
94 -- raises Capacity_Error (as no expansion of capacity is possible for a
97 function Default_Modulus
(Capacity
: Count_Type
) return Hash_Type
;
98 -- Returns a modulus value (hash table size) which is optimal for the
99 -- specified capacity (which corresponds to the maximum number of items).
101 function Length
(Container
: Set
) return Count_Type
;
102 -- Returns the number of items in the set
104 function Is_Empty
(Container
: Set
) return Boolean;
105 -- Equivalent to Length (Container) = 0
107 procedure Clear
(Container
: in out Set
);
108 -- Removes all of the items from the set
110 function Element
(Position
: Cursor
) return Element_Type
;
111 -- Returns the element of the node designated by the cursor
113 procedure Replace_Element
114 (Container
: in out Set
;
116 New_Item
: Element_Type
);
117 -- If New_Item is equivalent (as determined by calling Equivalent_Elements)
118 -- to the element of the node designated by Position, then New_Element is
119 -- assigned to that element. Otherwise, it calls Hash to determine the
120 -- bucket for New_Item. If the bucket is not empty, then it calls
121 -- Equivalent_Elements for each node in that bucket to determine whether
122 -- New_Item is equivalent to an element in that bucket. If
123 -- Equivalent_Elements returns True then Program_Error is raised (because
124 -- an element may appear only once in the set); otherwise, New_Item is
125 -- assigned to the node designated by Position, and the node is moved to
128 procedure Query_Element
130 Process
: not null access procedure (Element
: Element_Type
));
131 -- Calls Process with the element (having only a constant view) of the node
132 -- designed by the cursor.
134 procedure Assign
(Target
: in out Set
; Source
: Set
);
135 -- If Target denotes the same object as Source, then the operation has no
136 -- effect. If the Target capacity is less then the Source length, then
137 -- Assign raises Capacity_Error. Otherwise, Assign clears Target and then
138 -- copies the (active) elements from Source to Target.
142 Capacity
: Count_Type
:= 0;
143 Modulus
: Hash_Type
:= 0) return Set
;
144 -- Constructs a new set object whose elements correspond to Source. If the
145 -- Capacity parameter is 0, then the capacity of the result is the same as
146 -- the length of Source. If the Capacity parameter is equal or greater than
147 -- the length of Source, then the capacity of the result is the specified
148 -- value. Otherwise, Copy raises Capacity_Error. If the Modulus parameter
149 -- is 0, then the modulus of the result is the value returned by a call to
150 -- Default_Modulus with the capacity parameter determined as above;
151 -- otherwise the modulus of the result is the specified value.
153 procedure Move
(Target
: in out Set
; Source
: in out Set
);
154 -- Clears Target (if it's not empty), and then moves (not copies) the
155 -- buckets array and nodes from Source to Target.
158 (Container
: in out Set
;
159 New_Item
: Element_Type
;
160 Position
: out Cursor
;
161 Inserted
: out Boolean);
162 -- Conditionally inserts New_Item into the set. If New_Item is already in
163 -- the set, then Inserted returns False and Position designates the node
164 -- containing the existing element (which is not modified). If New_Item is
165 -- not already in the set, then Inserted returns True and Position
166 -- designates the newly-inserted node containing New_Item. The search for
167 -- an existing element works as follows. Hash is called to determine
168 -- New_Item's bucket; if the bucket is non-empty, then Equivalent_Elements
169 -- is called to compare New_Item to the element of each node in that
170 -- bucket. If the bucket is empty, or there were no equivalent elements in
171 -- the bucket, the search "fails" and the New_Item is inserted in the set
172 -- (and Inserted returns True); otherwise, the search "succeeds" (and
173 -- Inserted returns False).
175 procedure Insert
(Container
: in out Set
; New_Item
: Element_Type
);
176 -- Attempts to insert New_Item into the set, performing the usual insertion
177 -- search (which involves calling both Hash and Equivalent_Elements); if
178 -- the search succeeds (New_Item is equivalent to an element already in the
179 -- set, and so was not inserted), then this operation raises
180 -- Constraint_Error. (This version of Insert is similar to Replace, but
181 -- having the opposite exception behavior. It is intended for use when you
182 -- want to assert that the item is not already in the set.)
184 procedure Include
(Container
: in out Set
; New_Item
: Element_Type
);
185 -- Attempts to insert New_Item into the set. If an element equivalent to
186 -- New_Item is already in the set (the insertion search succeeded, and
187 -- hence New_Item was not inserted), then the value of New_Item is assigned
188 -- to the existing element. (This insertion operation only raises an
189 -- exception if cursor tampering occurs. It is intended for use when you
190 -- want to insert the item in the set, and you don't care whether an
191 -- equivalent element is already present.)
193 procedure Replace
(Container
: in out Set
; New_Item
: Element_Type
);
194 -- Searches for New_Item in the set; if the search fails (because an
195 -- equivalent element was not in the set), then it raises
196 -- Constraint_Error. Otherwise, the existing element is assigned the value
197 -- New_Item. (This is similar to Insert, but with the opposite exception
198 -- behavior. It is intended for use when you want to assert that the item
199 -- is already in the set.)
201 procedure Exclude
(Container
: in out Set
; Item
: Element_Type
);
202 -- Searches for Item in the set, and if found, removes its node from the
203 -- set and then deallocates it. The search works as follows. The operation
204 -- calls Hash to determine the item's bucket; if the bucket is not empty,
205 -- it calls Equivalent_Elements to compare Item to the element of each node
206 -- in the bucket. (This is the deletion analog of Include. It is intended
207 -- for use when you want to remove the item from the set, but don't care
208 -- whether the item is already in the set.)
210 procedure Delete
(Container
: in out Set
; Item
: Element_Type
);
211 -- Searches for Item in the set (which involves calling both Hash and
212 -- Equivalent_Elements). If the search fails, then the operation raises
213 -- Constraint_Error. Otherwise it removes the node from the set and then
214 -- deallocates it. (This is the deletion analog of non-conditional
215 -- Insert. It is intended for use when you want to assert that the item is
216 -- already in the set.)
218 procedure Delete
(Container
: in out Set
; Position
: in out Cursor
);
219 -- Removes the node designated by Position from the set, and then
220 -- deallocates the node. The operation calls Hash to determine the bucket,
221 -- and then compares Position to each node in the bucket until there's a
222 -- match (it does not call Equivalent_Elements).
224 procedure Union
(Target
: in out Set
; Source
: Set
);
225 -- Iterates over the Source set, and conditionally inserts each element
228 function Union
(Left
, Right
: Set
) return Set
;
229 -- The operation first copies the Left set to the result, and then iterates
230 -- over the Right set to conditionally insert each element into the result.
232 function "or" (Left
, Right
: Set
) return Set
renames Union
;
234 procedure Intersection
(Target
: in out Set
; Source
: Set
);
235 -- Iterates over the Target set (calling First and Next), calling Find to
236 -- determine whether the element is in Source. If an equivalent element is
237 -- not found in Source, the element is deleted from Target.
239 function Intersection
(Left
, Right
: Set
) return Set
;
240 -- Iterates over the Left set, calling Find to determine whether the
241 -- element is in Right. If an equivalent element is found, it is inserted
242 -- into the result set.
244 function "and" (Left
, Right
: Set
) return Set
renames Intersection
;
246 procedure Difference
(Target
: in out Set
; Source
: Set
);
247 -- Iterates over the Source (calling First and Next), calling Find to
248 -- determine whether the element is in Target. If an equivalent element is
249 -- found, it is deleted from Target.
251 function Difference
(Left
, Right
: Set
) return Set
;
252 -- Iterates over the Left set, calling Find to determine whether the
253 -- element is in the Right set. If an equivalent element is not found, the
254 -- element is inserted into the result set.
256 function "-" (Left
, Right
: Set
) return Set
renames Difference
;
258 procedure Symmetric_Difference
(Target
: in out Set
; Source
: Set
);
259 -- The operation iterates over the Source set, searching for the element
260 -- in Target (calling Hash and Equivalent_Elements). If an equivalent
261 -- element is found, it is removed from Target; otherwise it is inserted
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 Has_Element
(Position
: Cursor
) return Boolean;
318 -- Equivalent to Position /= No_Element
320 function Equivalent_Elements
(Left
, Right
: Cursor
) return Boolean;
321 -- Returns the result of calling Equivalent_Elements with the elements of
322 -- the nodes designated by cursors Left and Right.
324 function Equivalent_Elements
326 Right
: Element_Type
) return Boolean;
327 -- Returns the result of calling Equivalent_Elements with element of the
328 -- node designated by Left and element Right.
330 function Equivalent_Elements
331 (Left
: Element_Type
;
332 Right
: Cursor
) return Boolean;
333 -- Returns the result of calling Equivalent_Elements with element Left and
334 -- the element of the node designated by Right.
338 Process
: not null access procedure (Position
: Cursor
));
339 -- Calls Process for each node in the set
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
);
415 type Node_Type
is record
416 Element
: Element_Type
;
421 new Hash_Tables
.Generic_Bounded_Hash_Table_Types
(Node_Type
);
423 type Set
(Capacity
: Count_Type
; Modulus
: Hash_Type
) is
424 new HT_Types
.Hash_Table_Type
(Capacity
, Modulus
) with null record;
429 type Set_Access
is access all Set
;
430 for Set_Access
'Storage_Size use 0;
432 type Cursor
is record
433 Container
: Set_Access
;
438 (Stream
: not null access Root_Stream_Type
'Class;
441 for Cursor
'Write use Write
;
444 (Stream
: not null access Root_Stream_Type
'Class;
447 for Cursor
'Read use Read
;
449 No_Element
: constant Cursor
:= (Container
=> null, Node
=> 0);
452 (Stream
: not null access Root_Stream_Type
'Class;
455 for Set
'Write use Write
;
458 (Stream
: not null access Root_Stream_Type
'Class;
459 Container
: out Set
);
461 for Set
'Read use Read
;
463 Empty_Set
: constant Set
:=
464 (Hash_Table_Type
with Capacity
=> 0, Modulus
=> 0);
466 end Ada
.Containers
.Bounded_Hashed_Sets
;