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1 ------------------------------------------------------------------------------
2 -- --
3 -- GNAT LIBRARY COMPONENTS --
4 -- --
5 -- A D A . C O N T A I N E R S . H A S H E D _ M A P S --
6 -- --
7 -- S p e c --
8 -- --
9 -- Copyright (C) 2004-2007, 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 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. --
25 -- --
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. --
32 -- --
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;
40 generic
41 type Key_Type is private;
42 type Element_Type is private;
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 <>;
48 package Ada.Containers.Hashed_Maps is
49 pragma Preelaborate;
50 pragma Remote_Types;
52 type Map is tagged private;
53 pragma Preelaborable_Initialization (Map);
55 type Cursor is private;
56 pragma Preelaborable_Initialization (Cursor);
58 Empty_Map : constant Map;
59 -- Map objects declared without an initialization expression are
60 -- initialized to the value Empty_Map.
62 No_Element : constant Cursor;
63 -- Cursor objects declared without an initialization expression are
64 -- initialized to the value No_Element.
66 function "=" (Left, Right : Map) return Boolean;
67 -- For each key/element pair in Left, equality attempts to find the key in
68 -- Right; if a search fails the equality returns False. The search works by
69 -- calling Hash to find the bucket in the Right map that corresponds to the
70 -- Left key. If bucket is non-empty, then equality calls Equivalent_Keys
71 -- to compare the key (in Left) to the key of each node in the bucket (in
72 -- Right); if the keys are equivalent, then the equality test for this
73 -- key/element pair (in Left) completes by calling the element equality
74 -- operator to compare the element (in Left) to the element of the node
75 -- (in Right) whose key matched.
77 function Capacity (Container : Map) return Count_Type;
78 -- Returns the current capacity of the map. Capacity is the maximum length
79 -- before which rehashing in guaranteed not to occur.
81 procedure Reserve_Capacity (Container : in out Map; Capacity : Count_Type);
82 -- Adjusts the current capacity, by allocating a new buckets array. If the
83 -- requested capacity is less than the current capacity, then the capacity
84 -- is contracted (to a value not less than the curent length). If the
85 -- requested capacity is greater than the current capacity, then the
86 -- capacity is expanded (to a value not less than what is requested). In
87 -- either case, the nodes are rehashed from the old buckets array onto the
88 -- new buckets array (Hash is called once for each existing key in order to
89 -- compute the new index), and then the old buckets array is deallocated.
91 function Length (Container : Map) return Count_Type;
92 -- Returns the number of items in the map
94 function Is_Empty (Container : Map) return Boolean;
95 -- Equivalent to Length (Container) = 0
97 procedure Clear (Container : in out Map);
98 -- Removes all of the items from the map
100 function Key (Position : Cursor) return Key_Type;
101 -- Returns the key of the node designated by the cursor
103 function Element (Position : Cursor) return Element_Type;
104 -- Returns the element of the node designated by the cursor
106 procedure Replace_Element
107 (Container : in out Map;
108 Position : Cursor;
109 New_Item : Element_Type);
110 -- Assigns the value New_Item to the element designated by the cursor
112 procedure Query_Element
113 (Position : Cursor;
114 Process : not null access
115 procedure (Key : Key_Type; Element : Element_Type));
116 -- Calls Process with the key and element (both having only a constant
117 -- view) of the node designed by the cursor.
119 procedure Update_Element
120 (Container : in out Map;
121 Position : Cursor;
122 Process : not null access
123 procedure (Key : Key_Type; Element : in out Element_Type));
124 -- Calls Process with the key (with only a constant view) and element (with
125 -- a variable view) of the node designed by the cursor.
127 procedure Move (Target : in out Map; Source : in out Map);
128 -- Clears Target (if it's not empty), and then moves (not copies) the
129 -- buckets array and nodes from Source to Target.
131 procedure Insert
132 (Container : in out Map;
133 Key : Key_Type;
134 New_Item : Element_Type;
135 Position : out Cursor;
136 Inserted : out Boolean);
137 -- Conditionally inserts New_Item into the map. If Key is already in the
138 -- map, then Inserted returns False and Position designates the node
139 -- containing the existing key/element pair (neither of which is modified).
140 -- If Key is not already in the map, the Inserted returns True and Position
141 -- designates the newly-inserted node container Key and New_Item. The
142 -- search for the key works as follows. Hash is called to determine Key's
143 -- bucket; if the bucket is non-empty, then Equivalent_Keys is called to
144 -- compare Key to each node in that bucket. If the bucket is empty, or
145 -- there were no matching keys in the bucket, the search "fails" and the
146 -- key/item pair is inserted in the map (and Inserted returns True);
147 -- otherwise, the search "succeeds" (and Inserted returns False).
149 procedure Insert
150 (Container : in out Map;
151 Key : Key_Type;
152 Position : out Cursor;
153 Inserted : out Boolean);
154 -- The same as the (conditional) Insert that accepts an element parameter,
155 -- with the difference that if Inserted returns True, then the element of
156 -- the newly-inserted node is initialized to its default value.
158 procedure Insert
159 (Container : in out Map;
160 Key : Key_Type;
161 New_Item : Element_Type);
162 -- Attempts to insert Key into the map, performing the usual search (which
163 -- involves calling both Hash and Equivalent_Keys); if the search succeeds
164 -- (because Key is already in the map), then it raises Constraint_Error.
165 -- (This version of Insert is similar to Replace, but having the opposite
166 -- exception behavior. It is intended for use when you want to assert that
167 -- Key is not already in the map.)
169 procedure Include
170 (Container : in out Map;
171 Key : Key_Type;
172 New_Item : Element_Type);
173 -- Attempts to insert Key into the map. If Key is already in the map, then
174 -- both the existing key and element are assigned the values of Key and
175 -- New_Item, respectively. (This version of Insert only raises an exception
176 -- if cursor tampering occurs. It is intended for use when you want to
177 -- insert the key/element pair in the map, and you don't care whether Key
178 -- is already present.)
180 procedure Replace
181 (Container : in out Map;
182 Key : Key_Type;
183 New_Item : Element_Type);
184 -- Searches for Key in the map; if the search fails (because Key was not in
185 -- the map), then it raises Constraint_Error. Otherwise, both the existing
186 -- key and element are assigned the values of Key and New_Item rsp. (This
187 -- is similar to Insert, but with the opposite exception behavior. It is to
188 -- be used when you want to assert that Key is already in the map.)
190 procedure Exclude (Container : in out Map; Key : Key_Type);
191 -- Searches for Key in the map, and if found, removes its node from the map
192 -- and then deallocates it. The search works as follows. The operation
193 -- calls Hash to determine the key's bucket; if the bucket is not empty, it
194 -- calls Equivalent_Keys to compare Key to each key in the bucket. (This is
195 -- the deletion analog of Include. It is intended for use when you want to
196 -- remove the item from the map, but don't care whether the key is already
197 -- in the map.)
199 procedure Delete (Container : in out Map; Key : Key_Type);
200 -- Searches for Key in the map (which involves calling both Hash and
201 -- Equivalent_Keys). If the search fails, then the operation raises
202 -- Constraint_Eror. Otherwise it removes the node from the map and then
203 -- deallocates it. (This is the deletion analog of non-conditional
204 -- Insert. It is intended for use when you want to assert that the item is
205 -- already in the map.)
207 procedure Delete (Container : in out Map; Position : in out Cursor);
208 -- Removes the node designated by Position from the map, and then
209 -- deallocates the node. The operation calls Hash to determine the bucket,
210 -- and then compares Position to each node in the bucket until there's a
211 -- match (it does not call Equivalent_Keys).
213 function First (Container : Map) return Cursor;
214 -- Returns a cursor that designates the first non-empty bucket, by
215 -- searching from the beginning of the buckets array.
217 function Next (Position : Cursor) return Cursor;
218 -- Returns a cursor that designates the node that follows the current one
219 -- designated by Position. If Position designates the last node in its
220 -- bucket, the operation calls Hash to compute the index of this bucket,
221 -- and searches the buckets array for the first non-empty bucket, starting
222 -- from that index; otherwise, it simply follows the link to the next node
223 -- in the same bucket.
225 procedure Next (Position : in out Cursor);
226 -- Equivalent to Position := Next (Position)
228 function Find (Container : Map; Key : Key_Type) return Cursor;
229 -- Searches for Key in the map. Find calls Hash to determine the key's
230 -- bucket; if the bucket is not empty, it calls Equivalent_Keys to compare
231 -- Key to each key in the bucket. If the search succeeds, Find returns a
232 -- cursor designating the matching node; otherwise, it returns No_Element.
234 function Contains (Container : Map; Key : Key_Type) return Boolean;
235 -- Equivalent to Find (Container, Key) /= No_Element
237 function Element (Container : Map; Key : Key_Type) return Element_Type;
238 -- Equivalent to Element (Find (Container, Key))
240 function Has_Element (Position : Cursor) return Boolean;
241 -- Equivalent to Position /= No_Element
243 function Equivalent_Keys (Left, Right : Cursor) return Boolean;
244 -- Returns the result of calling Equivalent_Keys with the keys of the nodes
245 -- designated by cursors Left and Right.
247 function Equivalent_Keys (Left : Cursor; Right : Key_Type) return Boolean;
248 -- Returns the result of calling Equivalent_Keys with key of the node
249 -- designated by Left and key Right.
251 function Equivalent_Keys (Left : Key_Type; Right : Cursor) return Boolean;
252 -- Returns the result of calling Equivalent_Keys with key Left and the node
253 -- designated by Right.
255 procedure Iterate
256 (Container : Map;
257 Process : not null access procedure (Position : Cursor));
258 -- Calls Process for each node in the map
260 private
261 pragma Inline ("=");
262 pragma Inline (Length);
263 pragma Inline (Is_Empty);
264 pragma Inline (Clear);
265 pragma Inline (Key);
266 pragma Inline (Element);
267 pragma Inline (Move);
268 pragma Inline (Contains);
269 pragma Inline (Capacity);
270 pragma Inline (Reserve_Capacity);
271 pragma Inline (Has_Element);
272 pragma Inline (Equivalent_Keys);
273 pragma Inline (Next);
275 type Node_Type;
276 type Node_Access is access Node_Type;
278 type Node_Type is limited record
279 Key : Key_Type;
280 Element : Element_Type;
281 Next : Node_Access;
282 end record;
284 package HT_Types is new Hash_Tables.Generic_Hash_Table_Types
285 (Node_Type,
286 Node_Access);
288 type Map is new Ada.Finalization.Controlled with record
289 HT : HT_Types.Hash_Table_Type;
290 end record;
292 use HT_Types;
293 use Ada.Finalization;
295 overriding
296 procedure Adjust (Container : in out Map);
298 overriding
299 procedure Finalize (Container : in out Map);
301 use Ada.Streams;
303 procedure Write
304 (Stream : not null access Root_Stream_Type'Class;
305 Container : Map);
307 for Map'Write use Write;
309 procedure Read
310 (Stream : not null access Root_Stream_Type'Class;
311 Container : out Map);
313 for Map'Read use Read;
315 type Map_Access is access constant Map;
316 for Map_Access'Storage_Size use 0;
318 type Cursor is
319 record
320 Container : Map_Access;
321 Node : Node_Access;
322 end record;
324 procedure Read
325 (Stream : not null access Root_Stream_Type'Class;
326 Item : out Cursor);
328 for Cursor'Read use Read;
330 procedure Write
331 (Stream : not null access Root_Stream_Type'Class;
332 Item : Cursor);
334 for Cursor'Write use Write;
336 Empty_Map : constant Map := (Controlled with HT => (null, 0, 0, 0));
338 No_Element : constant Cursor := (Container => null, Node => null);
340 end Ada.Containers.Hashed_Maps;