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+------------------------------------------------------------------------------
+-- --
+-- GNAT RUN-TIME COMPONENTS --
+-- --
+-- G N A T . H E A P _ S O R T _ A --
+-- --
+-- S p e c --
+-- --
+-- Copyright (C) 1995-2008, AdaCore --
+-- --
+-- 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, 51 Franklin Street, Fifth Floor, --
+-- Boston, MA 02110-1301, 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.
+
+pragma Compiler_Unit;
+
+package GNAT.Heap_Sort_A is
+ pragma Preelaborate;
+
+ -- 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;