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Line No. Rev Author Line
1 706 jeremybenn
------------------------------------------------------------------------------
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--                                                                          --
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--                         GNAT LIBRARY COMPONENTS                          --
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--                                                                          --
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--                       ADA.CONTAINERS.GENERIC_SORT                        --
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--                                                                          --
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--                                 B o d y                                  --
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--                                                                          --
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--            Copyright (C) 2011, Free Software Foundation, Inc.            --
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--                                                                          --
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-- GNAT is free software;  you can  redistribute it  and/or modify it under --
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-- terms of the  GNU General Public License as published  by the Free Soft- --
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-- ware  Foundation;  either version 3,  or (at your option) any later ver- --
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-- sion.  GNAT is distributed in the hope that it will be useful, but WITH- --
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-- OUT ANY WARRANTY;  without even the  implied warranty of MERCHANTABILITY --
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-- or FITNESS FOR A PARTICULAR PURPOSE.                                     --
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--                                                                          --
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-- As a special exception under Section 7 of GPL version 3, you are granted --
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-- additional permissions described in the GCC Runtime Library Exception,   --
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-- version 3.1, as published by the Free Software Foundation.               --
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--                                                                          --
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-- You should have received a copy of the GNU General Public License and    --
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-- a copy of the GCC Runtime Library Exception along with this program;     --
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-- see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see    --
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-- <http://www.gnu.org/licenses/>.                                          --
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--                                                                          --
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-- This unit was originally developed by Matthew J Heaney.                  --
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------------------------------------------------------------------------------
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--  This algorithm was adapted from GNAT.Heap_Sort (see g-heasor.ad[sb])
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with System;
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procedure Ada.Containers.Generic_Sort (First, Last : Index_Type'Base) is
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   type T is range System.Min_Int .. System.Max_Int;
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   function To_Index (J : T) return Index_Type;
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   pragma Inline (To_Index);
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   function Lt (J, K : T) return Boolean;
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   pragma Inline (Lt);
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   procedure Xchg (J, K : T);
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   pragma Inline (Xchg);
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   procedure Sift (S : T);
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   --------------
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   -- To_Index --
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   --------------
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   function To_Index (J : T) return Index_Type is
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      K : constant T'Base := Index_Type'Pos (First) + J - T'(1);
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   begin
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      return Index_Type'Val (K);
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   end To_Index;
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   --------
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   -- Lt --
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   --------
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   function Lt (J, K : T) return Boolean is
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   begin
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      return Before (To_Index (J), To_Index (K));
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   end Lt;
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   ----------
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   -- Xchg --
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   ----------
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   procedure Xchg (J, K : T) is
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   begin
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      Swap (To_Index (J), To_Index (K));
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   end Xchg;
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   Max : T := Index_Type'Pos (Last) - Index_Type'Pos (First) + T'(1);
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   ----------
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   -- Sift --
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   ----------
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   procedure Sift (S : T) is
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      C      : T := S;
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      Son    : T;
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      Father : T;
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   begin
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      loop
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         Son := C + C;
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         if Son < Max then
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            if Lt (Son, Son + 1) then
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               Son := Son + 1;
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            end if;
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         elsif Son > Max then
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            exit;
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         end if;
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         Xchg (Son, C);
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         C := Son;
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      end loop;
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      while C /= S loop
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         Father := C / 2;
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         if Lt (Father, C) then
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            Xchg (Father, C);
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            C := Father;
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         else
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            exit;
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         end if;
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      end loop;
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   end Sift;
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--  Start of processing for Generic_Sort
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begin
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   for J in reverse 1 .. Max / 2 loop
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      Sift (J);
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   end loop;
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   while Max > 1 loop
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      Xchg (1, Max);
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      Max := Max - 1;
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      Sift (1);
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   end loop;
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end Ada.Containers.Generic_Sort;

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