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------------------------------------------------------------------------------
-- --
-- AI-302 Reference Implementation --
-- --
-- Copyright (C) 2003-2004 Matthew J Heaney --
-- --
-- The AI-302 Reference Implementation is free software; you can --
-- redistribute it and/or modify it under terms of the GNU General Public --
-- License as published by the Free Software Foundation; either version 2, --
-- or (at your option) any later version. Charles is distributed in the --
-- hope that it will be useful, but WITHOUT 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 --
-- Charles; see file COPYING.TXT. If not, write to the Free Software --
-- Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. --
-- --
-- --
-- The AI-302 Reference Implementation is maintained by Matthew J Heaney. --
-- --
-- mailto:matthewjheaney@earthlink.net --
-- http://home.earthlink.net/~matthewjheaney/index.html --
-- --
------------------------------------------------------------------------------
procedure AI302.Containers.Generic_Constrained_Array_Sort
(Container : in out Array_Type) is
function Is_Less (I, J : Index_Type) return Boolean is
pragma Inline (Is_Less);
begin
return Container (I) < Container (J);
end;
procedure Swap (I, J : Index_Type) is
pragma Inline (Swap);
EI : constant Element_Type := Container (I);
begin
Container (I) := Container (J);
Container (J) := EI;
end;
procedure 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 Is_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
--Debug (Lo, "low iter");
--Debug (Mid, "middle iter");
--Debug (Hi, "high iter");
if Is_Less (Lo, Mid) then
if Is_Less (Lo, Hi) then
if Is_Less (Mid, Hi) then
--Debug ("swapping lo and mid (mid is median)");
Swap (Lo, Mid);
else
--Debug ("swapping lo and hi (hi is median)");
Swap (Lo, Hi);
end if;
else
--Debug ("lo is median");
null; --lo is median
end if;
elsif Is_Less (Lo, Hi) then
--Debug ("lo is median");
null; --lo is median
elsif Is_Less (Mid, Hi) then
--Debug ("swapping lo and hi (hi is median)");
Swap (Lo, Hi);
else
--Debug ("swapping lo and mid (mid is median)");
Swap (Lo, Mid);
end if;
Pivot := Lo;
--Debug (Pivot, "median of three is done");
Outer :
loop
loop
exit Outer when not (Pivot < Hi);
if Is_Less (Hi, Pivot) then
--Debug (Hi, "hi < pivot");
Swap (Hi, Pivot);
Pivot := Hi;
Lo := Index_Type'Succ (Lo);
exit;
else
--Debug (Hi, "hi >= pivot");
Hi := Index_Type'Pred (Hi);
end if;
end loop;
loop
exit Outer when not (Lo < Pivot);
if Is_Less (Lo, Pivot) then
--Debug (Lo, "lo < pivot");
Lo := Index_Type'Succ (Lo);
else
--Debug (Lo, "lo >= pivot");
Swap (Lo, Pivot);
Pivot := Lo;
Hi := Index_Type'Pred (Hi);
exit;
end if;
end loop;
end loop Outer;
--Debug (pivot, "partition done");
Sort (First, Index_Type'Pred (Pivot));
Sort (Index_Type'Succ (Pivot), Last);
end Sort;
begin
Sort (Container'First, Container'Last);
end AI302.Containers.Generic_Constrained_Array_Sort;
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