1------------------------------------------------------------------------------
2--                                                                          --
3--                         GNAT LIBRARY COMPONENTS                          --
4--                                                                          --
5--              ADA.CONTAINERS.HASH_TABLES.GENERIC_OPERATIONS               --
6--                                                                          --
7--                                 S p e c                                  --
8--                                                                          --
9--          Copyright (C) 2004-2019, Free Software Foundation, Inc.         --
10--                                                                          --
11-- GNAT is free software;  you can  redistribute it  and/or modify it under --
12-- terms of the  GNU General Public License as published  by the Free Soft- --
13-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
14-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
15-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
16-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
17--                                                                          --
18-- As a special exception under Section 7 of GPL version 3, you are granted --
19-- additional permissions described in the GCC Runtime Library Exception,   --
20-- version 3.1, as published by the Free Software Foundation.               --
21--                                                                          --
22-- You should have received a copy of the GNU General Public License and    --
23-- a copy of the GCC Runtime Library Exception along with this program;     --
24-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
25-- <http://www.gnu.org/licenses/>.                                          --
26--                                                                          --
27-- This unit was originally developed by Matthew J Heaney.                  --
28------------------------------------------------------------------------------
29
30--  Hash_Table_Type is used to implement hashed containers. This package
31--  declares hash-table operations that do not depend on keys.
32
33with Ada.Streams;
34
35generic
36
37   with package HT_Types is
38     new Generic_Hash_Table_Types (<>);
39
40   use HT_Types, HT_Types.Implementation;
41
42   with function Hash_Node (Node : Node_Access) return Hash_Type;
43
44   with function Next (Node : Node_Access) return Node_Access;
45
46   with procedure Set_Next
47     (Node : Node_Access;
48      Next : Node_Access);
49
50    with function Copy_Node (Source : Node_Access) return Node_Access;
51
52   with procedure Free (X : in out Node_Access);
53
54package Ada.Containers.Hash_Tables.Generic_Operations is
55   pragma Preelaborate;
56
57   procedure Free_Hash_Table (Buckets : in out Buckets_Access);
58   --  First frees the nodes in all non-null buckets of Buckets, and then frees
59   --  the Buckets array itself.
60
61   function Index
62     (Buckets : Buckets_Type;
63      Node    : Node_Access) return Hash_Type;
64   pragma Inline (Index);
65   --  Uses the hash value of Node to compute its Buckets array index
66
67   function Index
68     (Hash_Table : Hash_Table_Type;
69      Node       : Node_Access) return Hash_Type;
70   pragma Inline (Index);
71   --  Uses the hash value of Node to compute its Hash_Table buckets array
72   --  index.
73
74   function Checked_Index
75     (Hash_Table : aliased in out Hash_Table_Type;
76      Buckets    : Buckets_Type;
77      Node       : Node_Access) return Hash_Type;
78   --  Calls Index, but also locks and unlocks the container, per AI05-0022, in
79   --  order to detect element tampering by the generic actual Hash function.
80
81   function Checked_Index
82     (Hash_Table : aliased in out Hash_Table_Type;
83      Node       : Node_Access) return Hash_Type;
84   --  Calls Checked_Index using Hash_Table's buckets array.
85
86   procedure Adjust (HT : in out Hash_Table_Type);
87   --  Used to implement controlled Adjust. It is assumed that HT has the value
88   --  of the bit-wise copy that immediately follows controlled Finalize.
89   --  Adjust first allocates a new buckets array for HT (having the same
90   --  length as the source), and then allocates a copy of each node of source.
91
92   procedure Finalize (HT : in out Hash_Table_Type);
93   --  Used to implement controlled Finalize. It first calls Clear to
94   --  deallocate any remaining nodes, and then deallocates the buckets array.
95
96   generic
97      with function Find
98        (HT  : Hash_Table_Type;
99         Key : Node_Access) return Boolean;
100   function Generic_Equal
101     (L, R : Hash_Table_Type) return Boolean;
102   --  Used to implement hashed container equality. For each node in hash table
103   --  L, it calls Find to search for an equivalent item in hash table R. If
104   --  Find returns False for any node then Generic_Equal terminates
105   --  immediately and returns False. Otherwise if Find returns True for every
106   --  node then Generic_Equal returns True.
107
108   procedure Clear (HT : in out Hash_Table_Type);
109   --  Deallocates each node in hash table HT. (Note that it only deallocates
110   --  the nodes, not the buckets array.) Program_Error is raised if the hash
111   --  table is busy.
112
113   procedure Move (Target, Source : in out Hash_Table_Type);
114   --  Moves (not copies) the buckets array and nodes from Source to
115   --  Target. Program_Error is raised if Source is busy. The Target is first
116   --  cleared to deallocate its nodes (implying that Program_Error is also
117   --  raised if Target is busy). Source is empty following the move.
118
119   function Capacity (HT : Hash_Table_Type) return Count_Type;
120   --  Returns the length of the buckets array
121
122   procedure Reserve_Capacity
123     (HT : in out Hash_Table_Type;
124      N  : Count_Type);
125   --  If N is greater than the current capacity, then it expands the buckets
126   --  array to at least the value N. If N is less than the current capacity,
127   --  then it contracts the buckets array. In either case existing nodes are
128   --  rehashed onto the new buckets array, and the old buckets array is
129   --  deallocated. Program_Error is raised if the hash table is busy.
130
131   procedure Delete_Node_At_Index
132     (HT   : in out Hash_Table_Type;
133      Indx : Hash_Type;
134      X    : in out Node_Access);
135   --  Delete a node whose bucket position is known. Used to remove a node
136   --  whose element has been modified through a key_preserving reference.
137   --  We cannot use the value of the element precisely because the current
138   --  value does not correspond to the hash code that determines the bucket.
139
140   procedure Delete_Node_Sans_Free
141     (HT : in out Hash_Table_Type;
142      X  : Node_Access);
143   --  Removes node X from the hash table without deallocating the node
144
145   function First
146     (HT       : Hash_Table_Type) return Node_Access;
147   function First
148     (HT       : Hash_Table_Type;
149      Position : out Hash_Type) return Node_Access;
150   --  Returns the head of the list in the first (lowest-index) non-empty
151   --  bucket. Position will be the index of the bucket of the first node.
152   --  It is provided so that clients can implement efficient iterators.
153
154   function Next
155     (HT   : aliased in out Hash_Table_Type;
156      Node : Node_Access) return Node_Access;
157   function Next
158     (HT       : aliased in out Hash_Table_Type;
159      Node     : Node_Access;
160      Position : in out Hash_Type) return Node_Access;
161   --  Returns the node that immediately follows Node. This corresponds to
162   --  either the next node in the same bucket, or (if Node is the last node in
163   --  its bucket) the head of the list in the first non-empty bucket that
164   --  follows.
165   --
166   --  If Node_Position is supplied, then it will be used as a starting point
167   --  for iteration (Node_Position must be the index of Node's buckets). If it
168   --  is not supplied, it will be recomputed. It is provided so that clients
169   --  can implement efficient iterators.
170
171   generic
172      with procedure Process (Node : Node_Access; Position : Hash_Type);
173   procedure Generic_Iteration_With_Position (HT : Hash_Table_Type);
174   --  Calls Process for each node in hash table HT
175
176   generic
177      with procedure Process (Node : Node_Access);
178   procedure Generic_Iteration (HT : Hash_Table_Type);
179   --  Calls Process for each node in hash table HT
180
181   generic
182      use Ada.Streams;
183      with procedure Write
184        (Stream : not null access Root_Stream_Type'Class;
185         Node   : Node_Access);
186   procedure Generic_Write
187     (Stream : not null access Root_Stream_Type'Class;
188      HT     : Hash_Table_Type);
189   --  Used to implement the streaming attribute for hashed containers. It
190   --  calls Write for each node to write its value into Stream.
191
192   generic
193      use Ada.Streams;
194      with function New_Node
195             (Stream : not null access Root_Stream_Type'Class)
196              return Node_Access;
197   procedure Generic_Read
198     (Stream : not null access Root_Stream_Type'Class;
199      HT     : out Hash_Table_Type);
200   --  Used to implement the streaming attribute for hashed containers. It
201   --  first clears hash table HT, then populates the hash table by calling
202   --  New_Node for each item in Stream.
203
204   function New_Buckets (Length : Hash_Type) return Buckets_Access;
205   pragma Inline (New_Buckets);
206   --  Allocate a new Buckets_Type array with bounds 0 .. Length - 1
207
208   procedure Free_Buckets (Buckets : in out Buckets_Access);
209   pragma Inline (Free_Buckets);
210   --  Unchecked_Deallocate Buckets
211
212   --  Note: New_Buckets and Free_Buckets are needed because Buckets_Access has
213   --  an empty pool.
214
215end Ada.Containers.Hash_Tables.Generic_Operations;
216