| ------------------------------------------------------------------------------ |
| -- -- |
| -- GNAT LIBRARY COMPONENTS -- |
| -- -- |
| -- ADA.CONTAINERS.GENERIC_SORT -- |
| -- -- |
| -- B o d y -- |
| -- -- |
| -- Copyright (C) 2011, 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 (see g-heasor.ad[sb]) |
| |
| with System; |
| |
| procedure Ada.Containers.Generic_Sort (First, Last : Index_Type'Base) is |
| type T is range System.Min_Int .. System.Max_Int; |
| |
| function To_Index (J : T) return Index_Type; |
| pragma Inline (To_Index); |
| |
| function Lt (J, K : T) return Boolean; |
| pragma Inline (Lt); |
| |
| procedure Xchg (J, K : T); |
| pragma Inline (Xchg); |
| |
| procedure Sift (S : T); |
| |
| -------------- |
| -- To_Index -- |
| -------------- |
| |
| function To_Index (J : T) return Index_Type is |
| K : constant T'Base := Index_Type'Pos (First) + J - T'(1); |
| begin |
| return Index_Type'Val (K); |
| end To_Index; |
| |
| -------- |
| -- Lt -- |
| -------- |
| |
| function Lt (J, K : T) return Boolean is |
| begin |
| return Before (To_Index (J), To_Index (K)); |
| end Lt; |
| |
| ---------- |
| -- Xchg -- |
| ---------- |
| |
| procedure Xchg (J, K : T) is |
| begin |
| Swap (To_Index (J), To_Index (K)); |
| end Xchg; |
| |
| Max : T := Index_Type'Pos (Last) - Index_Type'Pos (First) + T'(1); |
| |
| ---------- |
| -- Sift -- |
| ---------- |
| |
| procedure Sift (S : T) is |
| C : T := S; |
| Son : T; |
| Father : T; |
| |
| begin |
| loop |
| Son := C + C; |
| |
| if Son < Max then |
| if Lt (Son, Son + 1) then |
| Son := Son + 1; |
| end if; |
| elsif Son > Max then |
| exit; |
| end if; |
| |
| Xchg (Son, C); |
| C := Son; |
| end loop; |
| |
| while C /= S loop |
| Father := C / 2; |
| |
| if Lt (Father, C) then |
| Xchg (Father, C); |
| C := Father; |
| else |
| exit; |
| end if; |
| end loop; |
| end Sift; |
| |
| -- Start of processing for Generic_Sort |
| |
| begin |
| for J in reverse 1 .. Max / 2 loop |
| Sift (J); |
| end loop; |
| |
| while Max > 1 loop |
| Xchg (1, Max); |
| Max := Max - 1; |
| Sift (1); |
| end loop; |
| end Ada.Containers.Generic_Sort; |
