128 lines
4 KiB
Ada
128 lines
4 KiB
Ada
------------------------------------------------------------------------------
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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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