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-- --
-- --
-- G N A T . H E A P _ S O R T _ A --
-- --
-- S p e c --
-- --
-- Copyright (C) 1995-2002 Ada Core Technologies, 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 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, 59 Temple Place - Suite 330, Boston, --
-- MA 02111-1307, 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. --
-- --
-- GNAT was originally developed by the GNAT team at New York University. --
-- Extensive contributions were provided by Ada Core Technologies Inc. --
-- --
-- Heapsort using access to procedure parameters
-- This package provides a heap sort routine that works with access to
-- subprogram parameters, so that it can be used with different types with
-- shared sorting code. It is considered obsoleted by GNAT.Heap_Sort which
-- offers a similar routine with a more convenient interface.
-- This heapsort algorithm uses approximately N*log(N) compares in the
-- worst case and is in place with no additional storage required. See
-- the body for exact details of the algorithm used.
package GNAT.Heap_Sort_A is
pragma Preelaborate (Heap_Sort_A);
-- The data to be sorted is assumed to be indexed by integer values from
-- 1 to N, where N is the number of items to be sorted. In addition, the
-- index value zero is used for a temporary location used during the sort.
type Move_Procedure is access procedure (From : Natural; To : Natural);
-- A pointer to a procedure that moves the data item with index From to
-- the data item with index To. An index value of zero is used for moves
-- from and to the single temporary location used by the sort.
type Lt_Function is access function (Op1, Op2 : Natural) return Boolean;
-- A pointer to a function that compares two items and returns True if
-- the item with index Op1 is less than the item with index Op2, and False
-- if the Op1 item is greater than or equal to the Op2 item.
procedure Sort (N : Natural; Move : Move_Procedure; Lt : Lt_Function);
-- This procedures sorts items in the range from 1 to N into ascending
-- order making calls to Lt to do required comparisons, and Move to move
-- items around. Note that, as described above, both Move and Lt use a
-- single temporary location with index value zero. This sort is not
-- stable, i.e. the order of equal elements in the input is not preserved.
end GNAT.Heap_Sort_A;