gcc/ada/a-cgcaso.adb

   1 ------------------------------------------------------------------------------
   2 --                                                                          --
   3 --                         GNAT LIBRARY COMPONENTS                          --
   4 --                                                                          --
   5 --                      A D A . C O N T A I N E R S .                       --
   6 --       G E N E R I C _ C O N S T R A I N E D _ A R R A Y _ S O R T        --
   7 --                                                                          --
   8 --                                 B o d y                                  --
   9 --                                                                          --
  10 --          Copyright (C) 2004-2006, Free Software Foundation, Inc.         --
  11 --                                                                          --
  12 -- GNAT is free software;  you can  redistribute it  and/or modify it under --
  13 -- terms of the  GNU General Public License as published  by the Free Soft- --
  14 -- ware  Foundation;  either version 2,  or (at your option) any later ver- --
  15 -- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
  16 -- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
  17 -- or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License --
  18 -- for  more details.  You should have  received  a copy of the GNU General --
  19 -- Public License  distributed with GNAT;  see file COPYING.  If not, write --
  20 -- to  the  Free Software Foundation,  51  Franklin  Street,  Fifth  Floor, --
  21 -- Boston, MA 02110-1301, USA.                                              --
  22 --                                                                          --
  23 -- As a special exception,  if other files  instantiate  generics from this --
  24 -- unit, or you link  this unit with other files  to produce an executable, --
  25 -- this  unit  does not  by itself cause  the resulting  executable  to  be --
  26 -- covered  by the  GNU  General  Public  License.  This exception does not --
  27 -- however invalidate  any other reasons why  the executable file  might be --
  28 -- covered by the  GNU Public License.                                      --
  29 --                                                                          --
  30 -- This unit has originally being developed by Matthew J Heaney.            --
  31 ------------------------------------------------------------------------------
  32
  33 --  This algorithm was adapted from GNAT.Heap_Sort_G (see g-hesorg.ad[sb])
  34
  35 with System;
  36
  37 procedure Ada.Containers.Generic_Constrained_Array_Sort
  38   (Container : in out Array_Type)
  39 is
  40    type T is range System.Min_Int .. System.Max_Int;
  41
  42    function To_Index (J : T) return Index_Type;
  43    pragma Inline (To_Index);
  44
  45    procedure Sift (S : T);
  46
  47    A : Array_Type renames Container;
  48
  49    --------------
  50    -- To_Index --
  51    --------------
  52
  53    function To_Index (J : T) return Index_Type is
  54       K : constant T'Base := Index_Type'Pos (A'First) + J - T'(1);
  55    begin
  56       return Index_Type'Val (K);
  57    end To_Index;
  58
  59    Max  : T := A'Length;
  60    Temp : Element_Type;
  61
  62    ----------
  63    -- Sift --
  64    ----------
  65
  66    procedure Sift (S : T) is
  67       C   : T := S;
  68       Son : T;
  69
  70    begin
  71       loop
  72          Son := 2 * C;
  73
  74          exit when Son > Max;
  75
  76          declare
  77             Son_Index : Index_Type := To_Index (Son);
  78
  79          begin
  80             if Son < Max then
  81                if A (Son_Index) < A (Index_Type'Succ (Son_Index)) then
  82                   Son := Son + 1;
  83                   Son_Index := Index_Type'Succ (Son_Index);
  84                end if;
  85             end if;
  86
  87             A (To_Index (C)) := A (Son_Index);  -- Move (Son, C);
  88          end;
  89
  90          C := Son;
  91       end loop;
  92
  93       while C /= S loop
  94          declare
  95             Father      : constant T := C / 2;
  96             Father_Elem : Element_Type renames A (To_Index (Father));
  97
  98          begin
  99             if Father_Elem < Temp then           -- Lt (Father, 0)
 100                A (To_Index (C)) := Father_Elem;  -- Move (Father, C)
 101                C := Father;
 102
 103             else
 104                exit;
 105             end if;
 106          end;
 107       end loop;
 108
 109       A (To_Index (C)) := Temp; -- Move (0, C);
 110    end Sift;
 111
 112 --  Start of processing for Generic_Constrained_Array_Sort
 113
 114 begin
 115    for J in reverse 1 .. Max / 2 loop
 116       Temp := Container (To_Index (J)); --  Move (J, 0);
 117       Sift (J);
 118    end loop;
 119
 120    while Max > 1 loop
 121       declare
 122          Max_Elem : Element_Type renames A (To_Index (Max));
 123       begin
 124          Temp := Max_Elem;         --  Move (Max, 0);
 125          Max_Elem := A (A'First);  --  Move (1, Max);
 126       end;
 127
 128       Max := Max - 1;
 129       Sift (1);
 130    end loop;
 131 end Ada.Containers.Generic_Constrained_Array_Sort;