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
|
------------------------------------------------------------------------------
-- --
-- GNAT COMPILER COMPONENTS --
-- --
-- S Y S T E M . S T R I N G _ H A S H --
-- --
-- S p e c --
-- --
-- Copyright (C) 2009-2018, 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/>. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
------------------------------------------------------------------------------
-- This package provides a generic hashing function over strings, suitable for
-- use with a string keyed hash table. In particular, it is the basis for the
-- string hash functions in Ada.Containers.
--
-- The algorithm used here is not appropriate for applications that require
-- cryptographically strong hashes, or for application which wish to use very
-- wide hash values as pseudo unique identifiers. In such cases please refer
-- to GNAT.SHA1 and GNAT.MD5.
--
-- Note: this package is in the System hierarchy so that it can be directly
-- be used by other predefined packages. User access to this package is via
-- a renaming of this package in GNAT.String_Hash (file g-strhas.ads).
package System.String_Hash is
pragma Pure;
generic
type Char_Type is (<>);
-- The character type composing the key string type
type Key_Type is array (Positive range <>) of Char_Type;
-- The string type to use as a hash key
type Hash_Type is mod <>;
-- The type to be returned as a hash value. This must be a 32-bit
-- unsigned type with full range 0 .. 2**32-1, no other type is allowed
-- for this instantiation (checked in the body by Compile_Time_Error).
function Hash (Key : Key_Type) return Hash_Type;
pragma Inline (Hash);
-- Compute a hash value for a key
end System.String_Hash;
|
