gcc/ada/a-shcain.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --                    ADA.STRINGS.HASH_CASE_INSENSITIVE                     --
   6 --                                                                          --
   7 --                                 B o d y                                  --
   8 --                                                                          --
   9 --             Copyright (C) 2004 Free Software Foundation, Inc.            --
  10 --                                                                          --
  11 -- This specification is derived from the Ada Reference Manual for use with --
  12 -- GNAT. The copyright notice above, and the license provisions that follow --
  13 -- apply solely to the  contents of the part following the private keyword. --
  14 --                                                                          --
  15 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  16 -- terms of the  GNU General Public License as published  by the Free Soft- --
  17 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  18 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  19 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  20 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  21 -- for  more details.  You should have  received  a copy of the GNU General --
  22 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  23 -- to  the Free Software Foundation,  59 Temple Place - Suite 330,  Boston, --
  24 -- MA 02111-1307, USA.                                                      --
  25 --                                                                          --
  26 -- As a special exception,  if other files  instantiate  generics from this --
  27 -- unit, or you link  this unit with other files  to produce an executable, --
  28 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  29 -- covered  by the  GNU  General  Public  License.  This exception does not --
  30 -- however invalidate  any other reasons why  the executable file  might be --
  31 -- covered by the  GNU Public License.                                      --
  32 --                                                                          --
  33 -- This unit was originally developed by Matthew J Heaney.                  --
  34 ------------------------------------------------------------------------------
  35
  36 with Ada.Characters.Handling;  use Ada.Characters.Handling;
  37
  38 --  Note: source of this algorithm: GNAT.HTable.Hash (g-htable.adb)
  39
  40 function Ada.Strings.Hash_Case_Insensitive
  41   (Key : String) return Containers.Hash_Type
  42 is
  43    use Ada.Containers;
  44
  45    Tmp : Hash_Type;
  46
  47    function Rotate_Left
  48      (Value  : Hash_Type;
  49       Amount : Natural) return Hash_Type;
  50    pragma Import (Intrinsic, Rotate_Left);
  51
  52 begin
  53    Tmp := 0;
  54    for J in Key'Range loop
  55       Tmp := Rotate_Left (Tmp, 1) + Character'Pos (To_Lower (Key (J)));
  56    end loop;
  57
  58    return Tmp;
  59 end Ada.Strings.Hash_Case_Insensitive;
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