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------------------------------------------------------------------------------
-- --
-- GNAT LIBRARY COMPONENTS --
-- --
-- A D A . C O N T A I N E R S . --
-- G E N E R I C _ A N O N Y M O U S _ A R R A Y _ S O R T --
-- --
-- B o d y --
-- --
-- Copyright (C) 2004-2005 Free Software Foundation, Inc. --
-- --
-- This specification is derived from the Ada Reference Manual for use with --
-- GNAT. The copyright notice above, and the license provisions that follow --
-- apply solely to the contents of the part following the private keyword. --
-- --
-- GNAT is free software; you can redistribute it and/or modify it under --
-- terms of the GNU General Public License as published by the Free Soft- --
-- ware Foundation; either version 2, or (at your option) any later ver- --
-- sion. GNAT is distributed in the hope that it will be useful, but WITH- --
-- OUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY --
-- or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License --
-- for more details. You should have received a copy of the GNU General --
-- Public License distributed with GNAT; see file COPYING. If not, write --
-- to the Free Software Foundation, 51 Franklin Street, Fifth Floor, --
-- Boston, MA 02110-1301, USA. --
-- --
-- As a special exception, if other files instantiate generics from this --
-- unit, or you link this unit with other files to produce an executable, --
-- this unit does not by itself cause the resulting executable to be --
-- covered by the GNU General Public License. This exception does not --
-- however invalidate any other reasons why the executable file might be --
-- covered by the GNU Public License. --
-- --
-- This unit was originally developed by Matthew J Heaney. --
------------------------------------------------------------------------------
procedure Ada.Containers.Generic_Anonymous_Array_Sort
(First, Last : Index_Type'Base)
is
Pivot, Lo, Mid, Hi : Index_Type;
begin
if Last <= First then
return;
end if;
Lo := First;
Hi := Last;
if Last = Index_Type'Succ (First) then
if not Less (Lo, Hi) then
Swap (Lo, Hi);
end if;
return;
end if;
Mid := Index_Type'Val
(Index_Type'Pos (Lo) +
(Index_Type'Pos (Hi) - Index_Type'Pos (Lo)) / 2);
-- We need to figure out which case we have:
-- x < y < z
-- x < z < y
-- z < x < y
-- y < x < z
-- y < z < x
-- z < y < x
if Less (Lo, Mid) then
if Less (Lo, Hi) then
if Less (Mid, Hi) then
Swap (Lo, Mid);
else
Swap (Lo, Hi);
end if;
else
null; -- lo is median
end if;
elsif Less (Lo, Hi) then
null; -- lo is median
elsif Less (Mid, Hi) then
Swap (Lo, Hi);
else
Swap (Lo, Mid);
end if;
Pivot := Lo;
Outer : loop
loop
exit Outer when not (Pivot < Hi);
if Less (Hi, Pivot) then
Swap (Hi, Pivot);
Pivot := Hi;
Lo := Index_Type'Succ (Lo);
exit;
else
Hi := Index_Type'Pred (Hi);
end if;
end loop;
loop
exit Outer when not (Lo < Pivot);
if Less (Lo, Pivot) then
Lo := Index_Type'Succ (Lo);
else
Swap (Lo, Pivot);
Pivot := Lo;
Hi := Index_Type'Pred (Hi);
exit;
end if;
end loop;
end loop Outer;
Generic_Anonymous_Array_Sort (First, Index_Type'Pred (Pivot));
Generic_Anonymous_Array_Sort (Index_Type'Succ (Pivot), Last);
end Ada.Containers.Generic_Anonymous_Array_Sort;
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