1------------------------------------------------------------------------------ 2-- -- 3-- GNAT COMPILER COMPONENTS -- 4-- -- 5-- S Y S T E M . S T R I N G _ H A S H -- 6-- -- 7-- S p e c -- 8-- -- 9-- Copyright (C) 2009, 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-- GNAT was originally developed by the GNAT team at New York University. -- 28-- Extensive contributions were provided by Ada Core Technologies Inc. -- 29-- -- 30------------------------------------------------------------------------------ 31 32-- This package provides a generic hashing function over strings, suitable for 33-- use with a string keyed hash table. In particular, it is the basis for the 34-- string hash functions in Ada.Containers. 35-- 36-- The algorithm used here is not appropriate for applications that require 37-- cryptographically strong hashes, or for application which wish to use very 38-- wide hash values as pseudo unique identifiers. In such cases please refer 39-- to GNAT.SHA1 and GNAT.MD5. 40 41package System.String_Hash is 42 pragma Pure; 43 44 generic 45 type Char_Type is (<>); 46 -- The character type composing the key string type 47 48 type Key_Type is array (Positive range <>) of Char_Type; 49 -- The string type to use as a hash key 50 51 type Hash_Type is mod <>; 52 -- The type to be returned as a hash value. This must be a 32-bit 53 -- unsigned type with full range 0 .. 2**32-1, no other type is allowed 54 -- for this instantiation (checked in the body by Compile_Time_Error). 55 56 function Hash (Key : Key_Type) return Hash_Type; 57 pragma Inline (Hash); 58 -- Compute a hash value for a key 59 60end System.String_Hash; 61