File : a-cbhama.ads
1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT LIBRARY COMPONENTS --
4 -- --
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 _ M A P S --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 2004-2015, Free Software Foundation, Inc. --
10 -- --
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. --
14 -- --
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. --
21 -- --
22 -- --
23 -- --
24 -- --
25 -- --
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/>. --
30 -- --
31 -- This unit was originally developed by Matthew J Heaney. --
32 ------------------------------------------------------------------------------
33
34 with Ada.Iterator_Interfaces;
35
36 private with Ada.Containers.Hash_Tables;
37 private with Ada.Streams;
38 private with Ada.Finalization;
39
40 generic
41 type Key_Type is private;
42 type Element_Type is private;
43
44 with function Hash (Key : Key_Type) return Hash_Type;
45 with function Equivalent_Keys (Left, Right : Key_Type) return Boolean;
46 with function "=" (Left, Right : Element_Type) return Boolean is <>;
47
48 package Ada.Containers.Bounded_Hashed_Maps is
49 pragma Annotate (CodePeer, Skip_Analysis);
50 pragma Pure;
51 pragma Remote_Types;
52
53 type Map (Capacity : Count_Type; Modulus : Hash_Type) is tagged private with
54 Constant_Indexing => Constant_Reference,
55 Variable_Indexing => Reference,
56 Default_Iterator => Iterate,
57 Iterator_Element => Element_Type;
58
59 pragma Preelaborable_Initialization (Map);
60
61 type Cursor is private;
62 pragma Preelaborable_Initialization (Cursor);
63
64 Empty_Map : constant Map;
65 -- Map objects declared without an initialization expression are
66 -- initialized to the value Empty_Map.
67
68 No_Element : constant Cursor;
69 -- Cursor objects declared without an initialization expression are
70 -- initialized to the value No_Element.
71
72 function Has_Element (Position : Cursor) return Boolean;
73 -- Equivalent to Position /= No_Element
74
75 package Map_Iterator_Interfaces is new
76 Ada.Iterator_Interfaces (Cursor, Has_Element);
77
78 function "=" (Left, Right : Map) return Boolean;
79 -- For each key/element pair in Left, equality attempts to find the key in
80 -- Right; if a search fails the equality returns False. The search works by
81 -- calling Hash to find the bucket in the Right map that corresponds to the
82 -- Left key. If bucket is non-empty, then equality calls Equivalent_Keys
83 -- to compare the key (in Left) to the key of each node in the bucket (in
84 -- Right); if the keys are equivalent, then the equality test for this
85 -- key/element pair (in Left) completes by calling the element equality
86 -- operator to compare the element (in Left) to the element of the node
87 -- (in Right) whose key matched.
88
89 function Capacity (Container : Map) return Count_Type;
90 -- Returns the current capacity of the map. Capacity is the maximum length
91 -- before which rehashing in guaranteed not to occur.
92
93 procedure Reserve_Capacity (Container : in out Map; Capacity : Count_Type);
94 -- If the value of the Capacity actual parameter is less or equal to
95 -- Container.Capacity, then the operation has no effect. Otherwise it
96 -- raises Capacity_Error (as no expansion of capacity is possible for a
97 -- bounded form).
98
99 function Default_Modulus (Capacity : Count_Type) return Hash_Type;
100 -- Returns a modulus value (hash table size) which is optimal for the
101 -- specified capacity (which corresponds to the maximum number of items).
102
103 function Length (Container : Map) return Count_Type;
104 -- Returns the number of items in the map
105
106 function Is_Empty (Container : Map) return Boolean;
107 -- Equivalent to Length (Container) = 0
108
109 procedure Clear (Container : in out Map);
110 -- Removes all of the items from the map
111
112 function Key (Position : Cursor) return Key_Type;
113 -- Returns the key of the node designated by the cursor
114
115 function Element (Position : Cursor) return Element_Type;
116 -- Returns the element of the node designated by the cursor
117
118 procedure Replace_Element
119 (Container : in out Map;
120 Position : Cursor;
121 New_Item : Element_Type);
122 -- Assigns the value New_Item to the element designated by the cursor
123
124 procedure Query_Element
125 (Position : Cursor;
126 Process : not null access
127 procedure (Key : Key_Type; Element : Element_Type));
128 -- Calls Process with the key and element (both having only a constant
129 -- view) of the node designed by the cursor.
130
131 procedure Update_Element
132 (Container : in out Map;
133 Position : Cursor;
134 Process : not null access
135 procedure (Key : Key_Type; Element : in out Element_Type));
136 -- Calls Process with the key (with only a constant view) and element (with
137 -- a variable view) of the node designed by the cursor.
138
139 type Constant_Reference_Type
140 (Element : not null access constant Element_Type) is
141 private
142 with
143 Implicit_Dereference => Element;
144
145 type Reference_Type (Element : not null access Element_Type) is private
146 with
147 Implicit_Dereference => Element;
148
149 function Constant_Reference
150 (Container : aliased Map;
151 Position : Cursor) return Constant_Reference_Type;
152
153 function Reference
154 (Container : aliased in out Map;
155 Position : Cursor) return Reference_Type;
156
157 function Constant_Reference
158 (Container : aliased Map;
159 Key : Key_Type) return Constant_Reference_Type;
160
161 function Reference
162 (Container : aliased in out Map;
163 Key : Key_Type) return Reference_Type;
164
165 procedure Assign (Target : in out Map; Source : Map);
166 -- If Target denotes the same object as Source, then the operation has no
167 -- effect. If the Target capacity is less than the Source length, then
168 -- Assign raises Capacity_Error. Otherwise, Assign clears Target and then
169 -- copies the (active) elements from Source to Target.
170
171 function Copy
172 (Source : Map;
173 Capacity : Count_Type := 0;
174 Modulus : Hash_Type := 0) return Map;
175 -- Constructs a new set object whose elements correspond to Source. If the
176 -- Capacity parameter is 0, then the capacity of the result is the same as
177 -- the length of Source. If the Capacity parameter is equal or greater than
178 -- the length of Source, then the capacity of the result is the specified
179 -- value. Otherwise, Copy raises Capacity_Error. If the Modulus parameter
180 -- is 0, then the modulus of the result is the value returned by a call to
181 -- Default_Modulus with the capacity parameter determined as above;
182 -- otherwise the modulus of the result is the specified value.
183
184 procedure Move (Target : in out Map; Source : in out Map);
185 -- Clears Target (if it's not empty), and then moves (not copies) the
186 -- buckets array and nodes from Source to Target.
187
188 procedure Insert
189 (Container : in out Map;
190 Key : Key_Type;
191 New_Item : Element_Type;
192 Position : out Cursor;
193 Inserted : out Boolean);
194 -- Conditionally inserts New_Item into the map. If Key is already in the
195 -- map, then Inserted returns False and Position designates the node
196 -- containing the existing key/element pair (neither of which is modified).
197 -- If Key is not already in the map, the Inserted returns True and Position
198 -- designates the newly-inserted node container Key and New_Item. The
199 -- search for the key works as follows. Hash is called to determine Key's
200 -- bucket; if the bucket is non-empty, then Equivalent_Keys is called to
201 -- compare Key to each node in that bucket. If the bucket is empty, or
202 -- there were no matching keys in the bucket, the search "fails" and the
203 -- key/item pair is inserted in the map (and Inserted returns True);
204 -- otherwise, the search "succeeds" (and Inserted returns False).
205
206 procedure Insert
207 (Container : in out Map;
208 Key : Key_Type;
209 Position : out Cursor;
210 Inserted : out Boolean);
211 -- The same as the (conditional) Insert that accepts an element parameter,
212 -- with the difference that if Inserted returns True, then the element of
213 -- the newly-inserted node is initialized to its default value.
214
215 procedure Insert
216 (Container : in out Map;
217 Key : Key_Type;
218 New_Item : Element_Type);
219 -- Attempts to insert Key into the map, performing the usual search (which
220 -- involves calling both Hash and Equivalent_Keys); if the search succeeds
221 -- (because Key is already in the map), then it raises Constraint_Error.
222 -- (This version of Insert is similar to Replace, but having the opposite
223 -- exception behavior. It is intended for use when you want to assert that
224 -- Key is not already in the map.)
225
226 procedure Include
227 (Container : in out Map;
228 Key : Key_Type;
229 New_Item : Element_Type);
230 -- Attempts to insert Key into the map. If Key is already in the map, then
231 -- both the existing key and element are assigned the values of Key and
232 -- New_Item, respectively. (This version of Insert only raises an exception
233 -- if cursor tampering occurs. It is intended for use when you want to
234 -- insert the key/element pair in the map, and you don't care whether Key
235 -- is already present.)
236
237 procedure Replace
238 (Container : in out Map;
239 Key : Key_Type;
240 New_Item : Element_Type);
241 -- Searches for Key in the map; if the search fails (because Key was not in
242 -- the map), then it raises Constraint_Error. Otherwise, both the existing
243 -- key and element are assigned the values of Key and New_Item rsp. (This
244 -- is similar to Insert, but with the opposite exception behavior. It is to
245 -- be used when you want to assert that Key is already in the map.)
246
247 procedure Exclude (Container : in out Map; Key : Key_Type);
248 -- Searches for Key in the map, and if found, removes its node from the map
249 -- and then deallocates it. The search works as follows. The operation
250 -- calls Hash to determine the key's bucket; if the bucket is not empty, it
251 -- calls Equivalent_Keys to compare Key to each key in the bucket. (This is
252 -- the deletion analog of Include. It is intended for use when you want to
253 -- remove the item from the map, but don't care whether the key is already
254 -- in the map.)
255
256 procedure Delete (Container : in out Map; Key : Key_Type);
257 -- Searches for Key in the map (which involves calling both Hash and
258 -- Equivalent_Keys). If the search fails, then the operation raises
259 -- Constraint_Error. Otherwise it removes the node from the map and then
260 -- deallocates it. (This is the deletion analog of non-conditional
261 -- Insert. It is intended for use when you want to assert that the item is
262 -- already in the map.)
263
264 procedure Delete (Container : in out Map; Position : in out Cursor);
265 -- Removes the node designated by Position from the map, and then
266 -- deallocates the node. The operation calls Hash to determine the bucket,
267 -- and then compares Position to each node in the bucket until there's a
268 -- match (it does not call Equivalent_Keys).
269
270 function First (Container : Map) return Cursor;
271 -- Returns a cursor that designates the first non-empty bucket, by
272 -- searching from the beginning of the buckets array.
273
274 function Next (Position : Cursor) return Cursor;
275 -- Returns a cursor that designates the node that follows the current one
276 -- designated by Position. If Position designates the last node in its
277 -- bucket, the operation calls Hash to compute the index of this bucket,
278 -- and searches the buckets array for the first non-empty bucket, starting
279 -- from that index; otherwise, it simply follows the link to the next node
280 -- in the same bucket.
281
282 procedure Next (Position : in out Cursor);
283 -- Equivalent to Position := Next (Position)
284
285 function Find (Container : Map; Key : Key_Type) return Cursor;
286 -- Searches for Key in the map. Find calls Hash to determine the key's
287 -- bucket; if the bucket is not empty, it calls Equivalent_Keys to compare
288 -- Key to each key in the bucket. If the search succeeds, Find returns a
289 -- cursor designating the matching node; otherwise, it returns No_Element.
290
291 function Contains (Container : Map; Key : Key_Type) return Boolean;
292 -- Equivalent to Find (Container, Key) /= No_Element
293
294 function Element (Container : Map; Key : Key_Type) return Element_Type;
295 -- Equivalent to Element (Find (Container, Key))
296
297 function Equivalent_Keys (Left, Right : Cursor) return Boolean;
298 -- Returns the result of calling Equivalent_Keys with the keys of the nodes
299 -- designated by cursors Left and Right.
300
301 function Equivalent_Keys (Left : Cursor; Right : Key_Type) return Boolean;
302 -- Returns the result of calling Equivalent_Keys with key of the node
303 -- designated by Left and key Right.
304
305 function Equivalent_Keys (Left : Key_Type; Right : Cursor) return Boolean;
306 -- Returns the result of calling Equivalent_Keys with key Left and the node
307 -- designated by Right.
308
309 procedure Iterate
310 (Container : Map;
311 Process : not null access procedure (Position : Cursor));
312 -- Calls Process for each node in the map
313
314 function Iterate (Container : Map)
315 return Map_Iterator_Interfaces.Forward_Iterator'class;
316
317 private
318 pragma Inline (Length);
319 pragma Inline (Is_Empty);
320 pragma Inline (Clear);
321 pragma Inline (Key);
322 pragma Inline (Element);
323 pragma Inline (Move);
324 pragma Inline (Contains);
325 pragma Inline (Capacity);
326 pragma Inline (Reserve_Capacity);
327 pragma Inline (Has_Element);
328 pragma Inline (Next);
329
330 type Node_Type is record
331 Key : Key_Type;
332 Element : aliased Element_Type;
333 Next : Count_Type;
334 end record;
335
336 package HT_Types is
337 new Hash_Tables.Generic_Bounded_Hash_Table_Types (Node_Type);
338
339 type Map (Capacity : Count_Type; Modulus : Hash_Type) is
340 new HT_Types.Hash_Table_Type (Capacity, Modulus) with null record;
341
342 use HT_Types, HT_Types.Implementation;
343 use Ada.Streams;
344 use Ada.Finalization;
345
346 procedure Write
347 (Stream : not null access Root_Stream_Type'Class;
348 Container : Map);
349
350 for Map'Write use Write;
351
352 procedure Read
353 (Stream : not null access Root_Stream_Type'Class;
354 Container : out Map);
355
356 for Map'Read use Read;
357
358 type Map_Access is access all Map;
359 for Map_Access'Storage_Size use 0;
360
361 -- Note: If a Cursor object has no explicit initialization expression,
362 -- it must default initialize to the same value as constant No_Element.
363 -- The Node component of type Cursor has scalar type Count_Type, so it
364 -- requires an explicit initialization expression of its own declaration,
365 -- in order for objects of record type Cursor to properly initialize.
366
367 type Cursor is record
368 Container : Map_Access;
369 Node : Count_Type := 0;
370 end record;
371
372 procedure Read
373 (Stream : not null access Root_Stream_Type'Class;
374 Item : out Cursor);
375
376 for Cursor'Read use Read;
377
378 procedure Write
379 (Stream : not null access Root_Stream_Type'Class;
380 Item : Cursor);
381
382 for Cursor'Write use Write;
383
384 subtype Reference_Control_Type is Implementation.Reference_Control_Type;
385 -- It is necessary to rename this here, so that the compiler can find it
386
387 type Constant_Reference_Type
388 (Element : not null access constant Element_Type) is
389 record
390 Control : Reference_Control_Type :=
391 raise Program_Error with "uninitialized reference";
392 -- The RM says, "The default initialization of an object of
393 -- type Constant_Reference_Type or Reference_Type propagates
394 -- Program_Error."
395 end record;
396
397 procedure Write
398 (Stream : not null access Root_Stream_Type'Class;
399 Item : Constant_Reference_Type);
400
401 for Constant_Reference_Type'Write use Write;
402
403 procedure Read
404 (Stream : not null access Root_Stream_Type'Class;
405 Item : out Constant_Reference_Type);
406
407 for Constant_Reference_Type'Read use Read;
408
409 type Reference_Type (Element : not null access Element_Type) is record
410 Control : Reference_Control_Type :=
411 raise Program_Error with "uninitialized reference";
412 -- The RM says, "The default initialization of an object of
413 -- type Constant_Reference_Type or Reference_Type propagates
414 -- Program_Error."
415 end record;
416
417 procedure Write
418 (Stream : not null access Root_Stream_Type'Class;
419 Item : Reference_Type);
420
421 for Reference_Type'Write use Write;
422
423 procedure Read
424 (Stream : not null access Root_Stream_Type'Class;
425 Item : out Reference_Type);
426
427 for Reference_Type'Read use Read;
428
429 -- Three operations are used to optimize in the expansion of "for ... of"
430 -- loops: the Next(Cursor) procedure in the visible part, and the following
431 -- Pseudo_Reference and Get_Element_Access functions. See Sem_Ch5 for
432 -- details.
433
434 function Pseudo_Reference
435 (Container : aliased Map'Class) return Reference_Control_Type;
436 pragma Inline (Pseudo_Reference);
437 -- Creates an object of type Reference_Control_Type pointing to the
438 -- container, and increments the Lock. Finalization of this object will
439 -- decrement the Lock.
440
441 type Element_Access is access all Element_Type with
442 Storage_Size => 0;
443
444 function Get_Element_Access
445 (Position : Cursor) return not null Element_Access;
446 -- Returns a pointer to the element designated by Position.
447
448 Empty_Map : constant Map :=
449 (Hash_Table_Type with Capacity => 0, Modulus => 0);
450
451 No_Element : constant Cursor := (Container => null, Node => 0);
452
453 type Iterator is new Limited_Controlled and
454 Map_Iterator_Interfaces.Forward_Iterator with
455 record
456 Container : Map_Access;
457 end record
458 with Disable_Controlled => not T_Check;
459
460 overriding procedure Finalize (Object : in out Iterator);
461
462 overriding function First (Object : Iterator) return Cursor;
463
464 overriding function Next
465 (Object : Iterator;
466 Position : Cursor) return Cursor;
467
468 end Ada.Containers.Bounded_Hashed_Maps;