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. Also note that for bounded containers,
111   --  the buckets array is not dynamically allocated). Program_Error is raised
112   --  if the hash table is busy.
113
114   procedure Move (Target, Source : in out Hash_Table_Type);
115   --  Moves (not copies) the buckets array and nodes from Source to
116   --  Target. Program_Error is raised if Source is busy. The Target is first
117   --  cleared to deallocate its nodes (implying that Program_Error is also
118   --  raised if Target is busy). Source is empty following the move.
119
120   function Capacity (HT : Hash_Table_Type) return Count_Type;
121   --  Returns the length of the buckets array
122
123   procedure Reserve_Capacity
124     (HT : in out Hash_Table_Type;
125      N  : Count_Type);
126   --  If N is greater than the current capacity, then it expands the buckets
127   --  array to at least the value N. If N is less than the current capacity,
128   --  then it contracts the buckets array. In either case existing nodes are
129   --  rehashed onto the new buckets array, and the old buckets array is
130   --  deallocated. Program_Error is raised if the hash table is busy.
131
132   procedure Delete_Node_At_Index
133     (HT   : in out Hash_Table_Type;
134      Indx : Hash_Type;
135      X    : in out Node_Access);
136   --  Delete a node whose bucket position is known. Used to remove a node
137   --  whose element has been modified through a key_preserving reference.
138   --  We cannot use the value of the element precisely because the current
139   --  value does not correspond to the hash code that determines the bucket.
140
141   procedure Delete_Node_Sans_Free
142     (HT : in out Hash_Table_Type;
143      X  : Node_Access);
144   --  Removes node X from the hash table without deallocating the node
145
146   function First
147     (HT       : Hash_Table_Type) return Node_Access;
148   function First
149     (HT       : Hash_Table_Type;
150      Position : out Hash_Type) return Node_Access;
151   --  Returns the head of the list in the first (lowest-index) non-empty
152   --  bucket. Position will be the index of the bucket of the first node.
153   --  It is provided so that clients can implement efficient iterators.
154
155   function Next
156     (HT   : aliased in out Hash_Table_Type;
157      Node : Node_Access) return Node_Access;
158   function Next
159     (HT       : aliased in out Hash_Table_Type;
160      Node     : Node_Access;
161      Position : in out Hash_Type) return Node_Access;
162   --  Returns the node that immediately follows Node. This corresponds to
163   --  either the next node in the same bucket, or (if Node is the last node in
164   --  its bucket) the head of the list in the first non-empty bucket that
165   --  follows.
166   --
167   --  If Node_Position is supplied, then it will be used as a starting point
168   --  for iteration (Node_Position must be the index of Node's buckets). If it
169   --  is not supplied, it will be recomputed. It is provided so that clients
170   --  can implement efficient iterators.
171
172   generic
173      with procedure Process (Node : Node_Access; Position : Hash_Type);
174   procedure Generic_Iteration_With_Position (HT : Hash_Table_Type);
175   --  Calls Process for each node in hash table HT
176
177   generic
178      with procedure Process (Node : Node_Access);
179   procedure Generic_Iteration (HT : Hash_Table_Type);
180   --  Calls Process for each node in hash table HT
181
182   generic
183      use Ada.Streams;
184      with procedure Write
185        (Stream : not null access Root_Stream_Type'Class;
186         Node   : Node_Access);
187   procedure Generic_Write
188     (Stream : not null access Root_Stream_Type'Class;
189      HT     : Hash_Table_Type);
190   --  Used to implement the streaming attribute for hashed containers. It
191   --  calls Write for each node to write its value into Stream.
192
193   generic
194      use Ada.Streams;
195      with function New_Node
196             (Stream : not null access Root_Stream_Type'Class)
197              return Node_Access;
198   procedure Generic_Read
199     (Stream : not null access Root_Stream_Type'Class;
200      HT     : out Hash_Table_Type);
201   --  Used to implement the streaming attribute for hashed containers. It
202   --  first clears hash table HT, then populates the hash table by calling
203   --  New_Node for each item in Stream.
204
205   function New_Buckets (Length : Hash_Type) return Buckets_Access;
206   pragma Inline (New_Buckets);
207   --  Allocate a new Buckets_Type array with bounds 0 .. Length - 1
208
209   procedure Free_Buckets (Buckets : in out Buckets_Access);
210   pragma Inline (Free_Buckets);
211   --  Unchecked_Deallocate Buckets
212
213   --  Note: New_Buckets and Free_Buckets are needed because Buckets_Access has
214   --  an empty pool.
215
216end Ada.Containers.Hash_Tables.Generic_Operations;
217