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------------------------------------------------------------------------------
-- --
-- GNAT LIBRARY COMPONENTS --
-- --
-- ADA.CONTAINERS.GENERIC_CONSTRAINED_ARRAY_SORT --
-- --
-- B o d y --
-- --
-- Copyright (C) 2004-2021, Free Software Foundation, Inc. --
-- --
-- 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 3, 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. --
-- --
-- As a special exception under Section 7 of GPL version 3, you are granted --
-- additional permissions described in the GCC Runtime Library Exception, --
-- version 3.1, as published by the Free Software Foundation. --
-- --
-- You should have received a copy of the GNU General Public License and --
-- a copy of the GCC Runtime Library Exception along with this program; --
-- see the files COPYING3 and COPYING.RUNTIME respectively. If not, see --
-- <http://www.gnu.org/licenses/>. --
-- --
-- This unit was originally developed by Matthew J Heaney. --
------------------------------------------------------------------------------
-- This algorithm was adapted from GNAT.Heap_Sort_G (see g-hesorg.ad[sb])
procedure Ada.Containers.Generic_Constrained_Array_Sort
(Container : in out Array_Type)
is
subtype T is Long_Long_Integer;
function To_Index (J : T) return Index_Type;
pragma Inline (To_Index);
procedure Sift (S : T);
A : Array_Type renames Container;
--------------
-- To_Index --
--------------
function To_Index (J : T) return Index_Type is
K : constant T'Base := Index_Type'Pos (A'First) + J - T'(1);
begin
return Index_Type'Val (K);
end To_Index;
Max : T := A'Length;
Temp : Element_Type;
----------
-- Sift --
----------
procedure Sift (S : T) is
C : T := S;
Son : T;
begin
loop
Son := 2 * C;
exit when Son > Max;
declare
Son_Index : Index_Type := To_Index (Son);
begin
if Son < Max then
if A (Son_Index) < A (Index_Type'Succ (Son_Index)) then
Son := Son + 1;
Son_Index := Index_Type'Succ (Son_Index);
end if;
end if;
A (To_Index (C)) := A (Son_Index); -- Move (Son, C);
end;
C := Son;
end loop;
while C /= S loop
declare
Father : constant T := C / 2;
begin
if A (To_Index (Father)) < Temp then -- Lt (Father, 0)
A (To_Index (C)) := A (To_Index (Father)); -- Move (Father, C)
C := Father;
else
exit;
end if;
end;
end loop;
A (To_Index (C)) := Temp; -- Move (0, C);
end Sift;
-- Start of processing for Generic_Constrained_Array_Sort
begin
for J in reverse 1 .. Max / 2 loop
Temp := Container (To_Index (J)); -- Move (J, 0);
Sift (J);
end loop;
while Max > 1 loop
Temp := A (To_Index (Max)); -- Move (Max, 0);
A (To_Index (Max)) := A (A'First); -- Move (1, Max);
Max := Max - 1;
Sift (1);
end loop;
end Ada.Containers.Generic_Constrained_Array_Sort;