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