1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
|
------------------------------------------------------------------------------
-- --
-- GNAT LIBRARY COMPONENTS --
-- --
-- ADA.CONTAINERS.HASH_TABLES.GENERIC_BOUNDED_KEYS --
-- --
-- B o d y --
-- --
-- Copyright (C) 2004-2019, Free Software Foundation, Inc. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 3, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- This unit was originally developed by Matthew J Heaney. --
------------------------------------------------------------------------------
package body Ada.Containers.Hash_Tables.Generic_Bounded_Keys is
pragma Warnings (Off, "variable ""Busy*"" is not referenced");
pragma Warnings (Off, "variable ""Lock*"" is not referenced");
-- See comment in Ada.Containers.Helpers
-----------------------------
-- Checked_Equivalent_Keys --
-----------------------------
function Checked_Equivalent_Keys
(HT : aliased in out Hash_Table_Type'Class;
Key : Key_Type;
Node : Count_Type) return Boolean
is
Lock : With_Lock (HT.TC'Unrestricted_Access);
begin
return Equivalent_Keys (Key, HT.Nodes (Node));
end Checked_Equivalent_Keys;
-------------------
-- Checked_Index --
-------------------
function Checked_Index
(HT : aliased in out Hash_Table_Type'Class;
Key : Key_Type) return Hash_Type
is
Lock : With_Lock (HT.TC'Unrestricted_Access);
begin
return HT.Buckets'First + Hash (Key) mod HT.Buckets'Length;
end Checked_Index;
--------------------------
-- Delete_Key_Sans_Free --
--------------------------
procedure Delete_Key_Sans_Free
(HT : in out Hash_Table_Type'Class;
Key : Key_Type;
X : out Count_Type)
is
Indx : Hash_Type;
Prev : Count_Type;
begin
if HT.Length = 0 then
X := 0;
return;
end if;
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
TC_Check (HT.TC);
Indx := Checked_Index (HT, Key);
X := HT.Buckets (Indx);
if X = 0 then
return;
end if;
if Checked_Equivalent_Keys (HT, Key, X) then
TC_Check (HT.TC);
HT.Buckets (Indx) := Next (HT.Nodes (X));
HT.Length := HT.Length - 1;
return;
end if;
loop
Prev := X;
X := Next (HT.Nodes (Prev));
if X = 0 then
return;
end if;
if Checked_Equivalent_Keys (HT, Key, X) then
TC_Check (HT.TC);
Set_Next (HT.Nodes (Prev), Next => Next (HT.Nodes (X)));
HT.Length := HT.Length - 1;
return;
end if;
end loop;
end Delete_Key_Sans_Free;
----------
-- Find --
----------
function Find
(HT : Hash_Table_Type'Class;
Key : Key_Type) return Count_Type
is
Indx : Hash_Type;
Node : Count_Type;
begin
if HT.Length = 0 then
return 0;
end if;
Indx := Checked_Index (HT'Unrestricted_Access.all, Key);
Node := HT.Buckets (Indx);
while Node /= 0 loop
if Checked_Equivalent_Keys
(HT'Unrestricted_Access.all, Key, Node)
then
return Node;
end if;
Node := Next (HT.Nodes (Node));
end loop;
return 0;
end Find;
--------------------------------
-- Generic_Conditional_Insert --
--------------------------------
procedure Generic_Conditional_Insert
(HT : in out Hash_Table_Type'Class;
Key : Key_Type;
Node : out Count_Type;
Inserted : out Boolean)
is
Indx : Hash_Type;
begin
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
TC_Check (HT.TC);
Indx := Checked_Index (HT, Key);
Node := HT.Buckets (Indx);
if Node = 0 then
if Checks and then HT.Length = HT.Capacity then
raise Capacity_Error with "no more capacity for insertion";
end if;
Node := New_Node;
Set_Next (HT.Nodes (Node), Next => 0);
Inserted := True;
HT.Buckets (Indx) := Node;
HT.Length := HT.Length + 1;
return;
end if;
loop
if Checked_Equivalent_Keys (HT, Key, Node) then
Inserted := False;
return;
end if;
Node := Next (HT.Nodes (Node));
exit when Node = 0;
end loop;
if Checks and then HT.Length = HT.Capacity then
raise Capacity_Error with "no more capacity for insertion";
end if;
Node := New_Node;
Set_Next (HT.Nodes (Node), Next => HT.Buckets (Indx));
Inserted := True;
HT.Buckets (Indx) := Node;
HT.Length := HT.Length + 1;
end Generic_Conditional_Insert;
-----------------------------
-- Generic_Replace_Element --
-----------------------------
procedure Generic_Replace_Element
(HT : in out Hash_Table_Type'Class;
Node : Count_Type;
Key : Key_Type)
is
pragma Assert (HT.Length > 0);
pragma Assert (Node /= 0);
BB : Buckets_Type renames HT.Buckets;
NN : Nodes_Type renames HT.Nodes;
Old_Indx : Hash_Type;
New_Indx : constant Hash_Type := Checked_Index (HT, Key);
New_Bucket : Count_Type renames BB (New_Indx);
N, M : Count_Type;
begin
-- Per AI05-0022, the container implementation is required to detect
-- element tampering by a generic actual subprogram.
-- The following block appears to be vestigial -- this should be done
-- using Checked_Index instead. Also, we might have to move the actual
-- tampering checks to the top of the subprogram, in order to prevent
-- infinite recursion when calling Hash. (This is similar to how Insert
-- and Delete are implemented.) This implies that we will have to defer
-- the computation of New_Index until after the tampering check. ???
declare
Lock : With_Lock (HT.TC'Unrestricted_Access);
begin
Old_Indx := HT.Buckets'First + Hash (NN (Node)) mod HT.Buckets'Length;
end;
-- Replace_Element is allowed to change a node's key to Key
-- (generic formal operation Assign provides the mechanism), but
-- only if Key is not already in the hash table. (In a unique-key
-- hash table as this one, a key is mapped to exactly one node.)
if Checked_Equivalent_Keys (HT, Key, Node) then
TE_Check (HT.TC);
-- The new Key value is mapped to this same Node, so Node
-- stays in the same bucket.
Assign (NN (Node), Key);
return;
end if;
-- Key is not equivalent to Node, so we now have to determine if it's
-- equivalent to some other node in the hash table. This is the case
-- irrespective of whether Key is in the same or a different bucket from
-- Node.
N := New_Bucket;
while N /= 0 loop
if Checks and then Checked_Equivalent_Keys (HT, Key, N) then
pragma Assert (N /= Node);
raise Program_Error with
"attempt to replace existing element";
end if;
N := Next (NN (N));
end loop;
-- We have determined that Key is not already in the hash table, so
-- the change is tentatively allowed. We now perform the standard
-- checks to determine whether the hash table is locked (because you
-- cannot change an element while it's in use by Query_Element or
-- Update_Element), or if the container is busy (because moving a
-- node to a different bucket would interfere with iteration).
if Old_Indx = New_Indx then
-- The node is already in the bucket implied by Key. In this case
-- we merely change its value without moving it.
TE_Check (HT.TC);
Assign (NN (Node), Key);
return;
end if;
-- The node is a bucket different from the bucket implied by Key
TC_Check (HT.TC);
-- Do the assignment first, before moving the node, so that if Assign
-- propagates an exception, then the hash table will not have been
-- modified (except for any possible side-effect Assign had on Node).
Assign (NN (Node), Key);
-- Now we can safely remove the node from its current bucket
N := BB (Old_Indx); -- get value of first node in old bucket
pragma Assert (N /= 0);
if N = Node then -- node is first node in its bucket
BB (Old_Indx) := Next (NN (Node));
else
pragma Assert (HT.Length > 1);
loop
M := Next (NN (N));
pragma Assert (M /= 0);
if M = Node then
Set_Next (NN (N), Next => Next (NN (Node)));
exit;
end if;
N := M;
end loop;
end if;
-- Now we link the node into its new bucket (corresponding to Key)
Set_Next (NN (Node), Next => New_Bucket);
New_Bucket := Node;
end Generic_Replace_Element;
-----------
-- Index --
-----------
function Index
(HT : Hash_Table_Type'Class;
Key : Key_Type) return Hash_Type is
begin
return HT.Buckets'First + Hash (Key) mod HT.Buckets'Length;
end Index;
end Ada.Containers.Hash_Tables.Generic_Bounded_Keys;
|